This means that no unrelated I2C transactions are allowed on the parent I2C
adapter for the complete multiplexed I2C transaction.
The properties of mux-locked and parent-locked multiplexers are discussed
- in more detail in Documentation/i2c/i2c-topology.
+ in more detail in Documentation/i2c/i2c-topology.rst.
For each i2c child node, an I2C child bus will be created. They will
be numbered based on their order in the device tree.
----------------------
After loading the driver, you can instantiate the device as
-described in 'Documentation/i2c/instantiating-devices'.
+described in 'Documentation/i2c/instantiating-devices.rst'.
If you have multiple BMCs, each connected to your Satellite MC via
a different I2C bus, you can instantiate a device for each of
those BMCs.
If nothing happens when loading the adm1021 module, and you are certain
that your specific Xeon processor model includes compatible sensors, you
will have to explicitly instantiate the sensor chips from user-space. See
-method 4 in Documentation/i2c/instantiating-devices. Possible slave
+method 4 in Documentation/i2c/instantiating-devices.rst. Possible slave
addresses are 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e. It is likely that
only temp2 will be correct and temp1 will have to be ignored.
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
The ADM1075, unlike many other PMBus devices, does not support internal voltage
I2C address 0x27 by default, so an entry with I2C_BOARD_INFO("hih6130", 0x27)
can be used in the board setup code.
-Please see Documentation/i2c/instantiating-devices for details on how to
+Please see Documentation/i2c/instantiating-devices.rst for details on how to
instantiate I2C devices.
sysfs-Interface
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
Sysfs entries
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
This driver does not probe for devices, since there is no register which
can be safely used to identify the chip. You will have to instantiate
-the devices explicitly. Please see Documentation/i2c/instantiating-devices for
+the devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
WARNING: Do not access chip registers using the i2cdump command, and do not use
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
For MAX34446, the value of the currX_crit attribute determines if current or
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
Module parameters
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
This driver is part of the MFD driver named "menf21bmc" and does
not auto-detect devices.
You will have to instantiate the MFD driver explicitly.
-Please see Documentation/i2c/instantiating-devices for
+Please see Documentation/i2c/instantiating-devices.rst for
details.
Sysfs entries
The PCF8591 is plainly impossible to detect! Thus the driver won't even
try. You have to explicitly instantiate the device at the relevant
address (in the interval [0x48..0x4f]) either through platform data, or
-using the sysfs interface. See Documentation/i2c/instantiating-devices
+using the sysfs interface. See Documentation/i2c/instantiating-devices.rst
for details.
Directories are being created for each instantiated PCF8591:
The device communicates with the I2C protocol. Sensors can have the I2C
addresses 0x44 or 0x45, depending on the wiring. See
-Documentation/i2c/instantiating-devices for methods to instantiate the device.
+Documentation/i2c/instantiating-devices.rst for methods to instantiate the device.
There are two options configurable by means of sht3x_platform_data:
chip, which has the same electrical interface.
The device communicates with the I2C protocol. All sensors are set to I2C
-address 0x70. See Documentation/i2c/instantiating-devices for methods to
+address 0x70. See Documentation/i2c/instantiating-devices.rst for methods to
instantiate the device.
There are two options configurable by means of shtc1_platform_data:
Documentation/hwmon/sysfs-interface.rst under Temperatures).
Please refer how to instantiate this driver:
-Documentation/i2c/instantiating-devices
+Documentation/i2c/instantiating-devices.rst
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
The Via 686a southbridge has integrated hardware monitor functionality.
It also has an I2C bus, but this driver only supports the hardware monitor.
-For the I2C bus driver, see <file:Documentation/i2c/busses/i2c-viapro>
+For the I2C bus driver, see <file:Documentation/i2c/busses/i2c-viapro.rst>
The Via 686a implements three temperature sensors, two fan rotation speed
sensors, five voltage sensors and alarms.
-----------
This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices for
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
.. warning::
+=========================
Kernel driver i2c-ali1535
+=========================
Supported adapters:
* Acer Labs, Inc. ALI 1535 (south bridge)
+
Datasheet: Now under NDA
http://www.ali.com.tw/
Authors:
- Frodo Looijaard <frodol@dds.nl>,
- Philip Edelbrock <phil@netroedge.com>,
- Mark D. Studebaker <mdsxyz123@yahoo.com>,
- Dan Eaton <dan.eaton@rocketlogix.com>,
- Stephen Rousset<stephen.rousset@rocketlogix.com>
+ - Frodo Looijaard <frodol@dds.nl>,
+
- Philip Edelbrock <phil@netroedge.com>,
+ - Mark D. Studebaker <mdsxyz123@yahoo.com>,
+ - Dan Eaton <dan.eaton@rocketlogix.com>,
+ - Stephen Rousset<stephen.rousset@rocketlogix.com>
Description
-----------
+=========================
Kernel driver i2c-ali1563
+=========================
Supported adapters:
* Acer Labs, Inc. ALI 1563 (south bridge)
+
Datasheet: Now under NDA
http://www.ali.com.tw/
+=========================
Kernel driver i2c-ali15x3
+=========================
Supported adapters:
* Acer Labs, Inc. ALI 1533 and 1543C (south bridge)
+
Datasheet: Now under NDA
http://www.ali.com.tw/
Authors:
- Frodo Looijaard <frodol@dds.nl>,
- Philip Edelbrock <phil@netroedge.com>,
- Mark D. Studebaker <mdsxyz123@yahoo.com>
+ - Frodo Looijaard <frodol@dds.nl>,
+
- Philip Edelbrock <phil@netroedge.com>,
+ - Mark D. Studebaker <mdsxyz123@yahoo.com>
Module Parameters
-----------------
* force_addr: int
- Initialize the base address of the i2c controller
+ Initialize the base address of the i2c controller
Notes
lspci. Don't use this unless the driver complains that the base address is
not set.
-Example: 'modprobe i2c-ali15x3 force_addr=0xe800'
+Example::
+
+ modprobe i2c-ali15x3 force_addr=0xe800
SMBus periodically hangs on ASUS P5A motherboards and can only be cleared
by a power cycle. Cause unknown (see Issues below).
M1541 and M1543C South Bridges.
The M1543C is a South bridge for desktop systems.
+
The M1541 is a South bridge for portable systems.
+
They are part of the following ALI chipsets:
* "Aladdin Pro 2" includes the M1621 Slot 1 North bridge with AGP and
- 100MHz CPU Front Side bus
+ 100MHz CPU Front Side bus
* "Aladdin V" includes the M1541 Socket 7 North bridge with AGP and 100MHz
- CPU Front Side bus
+ CPU Front Side bus
+
Some Aladdin V motherboards:
- Asus P5A
- Atrend ATC-5220
- BCM/GVC VP1541
- Biostar M5ALA
- Gigabyte GA-5AX (** Generally doesn't work because the BIOS doesn't
- enable the 7101 device! **)
- Iwill XA100 Plus
- Micronics C200
- Microstar (MSI) MS-5169
+ - Asus P5A
+ - Atrend ATC-5220
+ - BCM/GVC VP1541
+ - Biostar M5ALA
+ - Gigabyte GA-5AX (Generally doesn't work because the BIOS doesn't
+ enable the 7101 device!)
+ - Iwill XA100 Plus
+ - Micronics C200
+ - Microstar (MSI) MS-5169
* "Aladdin IV" includes the M1541 Socket 7 North bridge
- with host bus up to 83.3 MHz.
+ with host bus up to 83.3 MHz.
For an overview of these chips see http://www.acerlabs.com. At this time the
full data sheets on the web site are password protected, however if you
contact the ALI office in San Jose they may give you the password.
The M1533/M1543C devices appear as FOUR separate devices on the PCI bus. An
-output of lspci will show something similar to the following:
+output of lspci will show something similar to the following::
00:02.0 USB Controller: Acer Laboratories Inc. M5237 (rev 03)
00:03.0 Bridge: Acer Laboratories Inc. M7101 <= THIS IS THE ONE WE NEED
00:07.0 ISA bridge: Acer Laboratories Inc. M1533 (rev c3)
00:0f.0 IDE interface: Acer Laboratories Inc. M5229 (rev c1)
-** IMPORTANT **
-** If you have a M1533 or M1543C on the board and you get
-** "ali15x3: Error: Can't detect ali15x3!"
-** then run lspci.
-** If you see the 1533 and 5229 devices but NOT the 7101 device,
-** then you must enable ACPI, the PMU, SMB, or something similar
-** in the BIOS.
-** The driver won't work if it can't find the M7101 device.
+.. important::
+
+ If you have a M1533 or M1543C on the board and you get
+ "ali15x3: Error: Can't detect ali15x3!"
+ then run lspci.
+
+ If you see the 1533 and 5229 devices but NOT the 7101 device,
+ then you must enable ACPI, the PMU, SMB, or something similar
+ in the BIOS.
+
+ The driver won't work if it can't find the M7101 device.
The SMB controller is part of the M7101 device, which is an ACPI-compliant
Power Management Unit (PMU).
On the P5A, the W83781D sensor chip is on both the ISA and
SMBus. Therefore the SMBus hangs can generally be avoided
by accessing the W83781D on the ISA bus only.
-
+++ /dev/null
-Kernel driver i2c-amd-mp2
-
-Supported adapters:
- * AMD MP2 PCIe interface
-
-Datasheet: not publicly available.
-
-Authors:
- Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
- Nehal Shah <nehal-bakulchandra.shah@amd.com>
- Elie Morisse <syniurge@gmail.com>
-
-Description
------------
-
-The MP2 is an ARM processor programmed as an I2C controller and communicating
-with the x86 host through PCI.
-
-If you see something like this:
-
-03:00.7 MP2 I2C controller: Advanced Micro Devices, Inc. [AMD] Device 15e6
-
-in your 'lspci -v', then this driver is for your device.
--- /dev/null
+=========================
+Kernel driver i2c-amd-mp2
+=========================
+
+Supported adapters:
+ * AMD MP2 PCIe interface
+
+Datasheet: not publicly available.
+
+Authors:
+ - Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
+ - Nehal Shah <nehal-bakulchandra.shah@amd.com>
+ - Elie Morisse <syniurge@gmail.com>
+
+Description
+-----------
+
+The MP2 is an ARM processor programmed as an I2C controller and communicating
+with the x86 host through PCI.
+
+If you see something like this::
+
+ 03:00.7 MP2 I2C controller: Advanced Micro Devices, Inc. [AMD] Device 15e6
+
+in your ``lspci -v``, then this driver is for your device.
+========================
Kernel driver i2c-amd756
+========================
Supported adapters:
* AMD 756
* AMD 766
* AMD 768
* AMD 8111
+
Datasheets: Publicly available on AMD website
* nVidia nForce
+
Datasheet: Unavailable
Authors:
- Frodo Looijaard <frodol@dds.nl>,
- Philip Edelbrock <phil@netroedge.com>
+ - Frodo Looijaard <frodol@dds.nl>,
+ - Philip Edelbrock <phil@netroedge.com>
Description
-----------
+=========================
Kernel driver i2c-adm8111
+=========================
Supported adapters:
* AMD-8111 SMBus 2.0 PCI interface
Description
-----------
-If you see something like this:
+If you see something like this::
-00:07.2 SMBus: Advanced Micro Devices [AMD] AMD-8111 SMBus 2.0 (rev 02)
- Subsystem: Advanced Micro Devices [AMD] AMD-8111 SMBus 2.0
- Flags: medium devsel, IRQ 19
- I/O ports at d400 [size=32]
+ 00:07.2 SMBus: Advanced Micro Devices [AMD] AMD-8111 SMBus 2.0 (rev 02)
+ Subsystem: Advanced Micro Devices [AMD] AMD-8111 SMBus 2.0
+ Flags: medium devsel, IRQ 19
+ I/O ports at d400 [size=32]
-in your 'lspci -v', then this driver is for your chipset.
+in your ``lspci -v``, then this driver is for your chipset.
Process Call Support
--------------------
+============================
Kernel driver i2c-diolan-u2c
+============================
Supported adapters:
* Diolan U2C-12 I2C-USB adapter
+
Documentation:
http://www.diolan.com/i2c/u2c12.html
+======================
Kernel driver i2c-i801
+======================
+
Supported adapters:
* Intel 82801AA and 82801AB (ICH and ICH0 - part of the
* Intel Comet Lake (PCH)
* Intel Elkhart Lake (PCH)
* Intel Tiger Lake (PCH)
+
Datasheets: Publicly available at the Intel website
On Intel Patsburg and later chipsets, both the normal host SMBus controller
and the additional 'Integrated Device Function' controllers are supported.
-Authors:
- Mark Studebaker <mdsxyz123@yahoo.com>
- Jean Delvare <jdelvare@suse.de>
+Authors:
+ - Mark Studebaker <mdsxyz123@yahoo.com>
+ - Jean Delvare <jdelvare@suse.de>
Module Parameters
-----------------
* disable_features (bit vector)
+
Disable selected features normally supported by the device. This makes it
possible to work around possible driver or hardware bugs if the feature in
question doesn't work as intended for whatever reason. Bit values:
+
+ ==== =========================================
0x01 disable SMBus PEC
0x02 disable the block buffer
0x08 disable the I2C block read functionality
0x10 don't use interrupts
0x20 disable SMBus Host Notify
+ ==== =========================================
Description
The ICH chips contain at least SEVEN separate PCI functions in TWO logical
PCI devices. An output of lspci will show something similar to the
-following:
+following::
00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01)
00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01)
hardware monitoring chip), you need to add your board to the list.
The motherboard is identified using the subvendor and subdevice IDs of the
-host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0":
+host bridge PCI device. Get yours with ``lspci -n -v -s 00:00.0``::
-00:00.0 Class 0600: 8086:2570 (rev 02)
- Subsystem: 1043:80f2
- Flags: bus master, fast devsel, latency 0
- Memory at fc000000 (32-bit, prefetchable) [size=32M]
- Capabilities: [e4] #09 [2106]
- Capabilities: [a0] AGP version 3.0
+ 00:00.0 Class 0600: 8086:2570 (rev 02)
+ Subsystem: 1043:80f2
+ Flags: bus master, fast devsel, latency 0
+ Memory at fc000000 (32-bit, prefetchable) [size=32M]
+ Capabilities: [e4] #09 [2106]
+ Capabilities: [a0] AGP version 3.0
Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043
(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic
anything interesting on your hidden ICH SMBus.
-**********************
+----------------------------------------------------------------------------
+
The lm_sensors project gratefully acknowledges the support of Texas
Instruments in the initial development of this driver.
+======================
Kernel driver i2c-ismt
+======================
+
Supported adapters:
* Intel S12xx series SOCs
-----------------
* bus_speed (unsigned int)
+
Allows changing of the bus speed. Normally, the bus speed is set by the BIOS
and never needs to be changed. However, some SMBus analyzers are too slow for
monitoring the bus during debug, thus the need for this module parameter.
Specify the bus speed in kHz.
+
Available bus frequency settings:
- 0 no change
- 80 kHz
- 100 kHz
- 400 kHz
- 1000 kHz
+
+ ==== =========
+ 0 no change
+ 80 kHz
+ 100 kHz
+ 400 kHz
+ 1000 kHz
+ ==== =========
Description
targeted primarily at the microserver and storage markets.
The S12xx series contain a pair of PCI functions. An output of lspci will show
-something similar to the following:
+something similar to the following::
00:13.0 System peripheral: Intel Corporation Centerton SMBus 2.0 Controller 0
00:13.1 System peripheral: Intel Corporation Centerton SMBus 2.0 Controller 1
+==================
Driver i2c-mlxcpld
+==================
Author: Michael Shych <michaelsh@mellanox.com>
This is the Mellanox I2C controller logic, implemented in Lattice CPLD
device.
+
Device supports:
- Master mode.
- One physical bus.
- Write Byte/Block.
Registers:
+
+=============== === =======================================================================
CPBLTY 0x0 - capability reg.
Bits [6:5] - transaction length. b01 - 72B is supported,
36B in other case.
For read transactions address is sent in a separate transaction and
specified in the four first bytes (DATA0 - DATA3). Data is read
starting from DATA0.
+=============== === =======================================================================
+=========================
Kernel driver i2c-nforce2
+=========================
Supported adapters:
- * nForce2 MCP 10de:0064
- * nForce2 Ultra 400 MCP 10de:0084
- * nForce3 Pro150 MCP 10de:00D4
- * nForce3 250Gb MCP 10de:00E4
+ * nForce2 MCP 10de:0064
+ * nForce2 Ultra 400 MCP 10de:0084
+ * nForce3 Pro150 MCP 10de:00D4
+ * nForce3 250Gb MCP 10de:00E4
* nForce4 MCP 10de:0052
* nForce4 MCP-04 10de:0034
* nForce MCP51 10de:0264
* nForce MCP78S 10de:0752
* nForce MCP79 10de:0AA2
-Datasheet: not publicly available, but seems to be similar to the
+Datasheet:
+ not publicly available, but seems to be similar to the
AMD-8111 SMBus 2.0 adapter.
Authors:
- Hans-Frieder Vogt <hfvogt@gmx.net>,
- Thomas Leibold <thomas@plx.com>,
- Patrick Dreker <patrick@dreker.de>
-
+ - Hans-Frieder Vogt <hfvogt@gmx.net>,
+ - Thomas Leibold <thomas@plx.com>,
+
- Patrick Dreker <patrick@dreker.de>
+
Description
-----------
i2c-nforce2 is a driver for the SMBuses included in the nVidia nForce2 MCP.
-If your 'lspci -v' listing shows something like the following,
+If your ``lspci -v`` listing shows something like the following::
-00:01.1 SMBus: nVidia Corporation: Unknown device 0064 (rev a2)
- Subsystem: Asustek Computer, Inc.: Unknown device 0c11
- Flags: 66Mhz, fast devsel, IRQ 5
- I/O ports at c000 [size=32]
- Capabilities: <available only to root>
+ 00:01.1 SMBus: nVidia Corporation: Unknown device 0064 (rev a2)
+ Subsystem: Asustek Computer, Inc.: Unknown device 0c11
+ Flags: 66Mhz, fast devsel, IRQ 5
+ I/O ports at c000 [size=32]
+
Capabilities: <available only to root>
then this driver should support the SMBuses of your motherboard.
+============================
Kernel driver i2c-nvidia-gpu
+============================
Datasheet: not publicly available.
i2c-nvidia-gpu is a driver for I2C controller included in NVIDIA Turing
and later GPUs and it is used to communicate with Type-C controller on GPUs.
-If your 'lspci -v' listing shows something like the following,
+If your ``lspci -v`` listing shows something like the following::
-01:00.3 Serial bus controller [0c80]: NVIDIA Corporation Device 1ad9 (rev a1)
+ 01:00.3 Serial bus controller [0c80]: NVIDIA Corporation Device 1ad9 (rev a1)
then this driver should support the I2C controller of your GPU.
+========================
Kernel driver i2c-ocores
+========================
Supported adapters:
* OpenCores.org I2C controller by Richard Herveille (see datasheet link)
There is also a possibility to attach a list of i2c_board_info which
the i2c-ocores driver will add to the bus upon creation.
-E.G. something like:
+E.G. something like::
-static struct resource ocores_resources[] = {
+ static struct resource ocores_resources[] = {
[0] = {
.start = MYI2C_BASEADDR,
.end = MYI2C_BASEADDR + 8,
.end = MYI2C_IRQ,
.flags = IORESOURCE_IRQ,
},
-};
+ };
-/* optional board info */
-struct i2c_board_info ocores_i2c_board_info[] = {
+ /* optional board info */
+ struct i2c_board_info ocores_i2c_board_info[] = {
{
I2C_BOARD_INFO("tsc2003", 0x48),
.platform_data = &tsc2003_platform_data,
I2C_BOARD_INFO("adv7180", 0x42 >> 1),
.irq = ADV_IRQ
}
-};
+ };
-static struct ocores_i2c_platform_data myi2c_data = {
+ static struct ocores_i2c_platform_data myi2c_data = {
.regstep = 2, /* two bytes between registers */
.clock_khz = 50000, /* input clock of 50MHz */
.devices = ocores_i2c_board_info, /* optional table of devices */
.num_devices = ARRAY_SIZE(ocores_i2c_board_info), /* table size */
-};
+ };
-static struct platform_device myi2c = {
+ static struct platform_device myi2c = {
.name = "ocores-i2c",
.dev = {
.platform_data = &myi2c_data,
},
.num_resources = ARRAY_SIZE(ocores_resources),
.resource = ocores_resources,
-};
+ };
+++ /dev/null
-Kernel driver i2c-parport
-
-Author: Jean Delvare <jdelvare@suse.de>
-
-This is a unified driver for several i2c-over-parallel-port adapters,
-such as the ones made by Philips, Velleman or ELV. This driver is
-meant as a replacement for the older, individual drivers:
- * i2c-philips-par
- * i2c-elv
- * i2c-velleman
- * video/i2c-parport (NOT the same as this one, dedicated to home brew
- teletext adapters)
-
-It currently supports the following devices:
- * (type=0) Philips adapter
- * (type=1) home brew teletext adapter
- * (type=2) Velleman K8000 adapter
- * (type=3) ELV adapter
- * (type=4) Analog Devices ADM1032 evaluation board
- * (type=5) Analog Devices evaluation boards: ADM1025, ADM1030, ADM1031
- * (type=6) Barco LPT->DVI (K5800236) adapter
- * (type=7) One For All JP1 parallel port adapter
- * (type=8) VCT-jig
-
-These devices use different pinout configurations, so you have to tell
-the driver what you have, using the type module parameter. There is no
-way to autodetect the devices. Support for different pinout configurations
-can be easily added when needed.
-
-Earlier kernels defaulted to type=0 (Philips). But now, if the type
-parameter is missing, the driver will simply fail to initialize.
-
-SMBus alert support is available on adapters which have this line properly
-connected to the parallel port's interrupt pin.
-
-
-Building your own adapter
--------------------------
-
-If you want to build you own i2c-over-parallel-port adapter, here is
-a sample electronics schema (credits go to Sylvain Munaut):
-
-Device PC
-Side ___________________Vdd (+) Side
- | | |
- --- --- ---
- | | | | | |
- |R| |R| |R|
- | | | | | |
- --- --- ---
- | | |
- | | /| |
-SCL ----------x--------o |-----------x------------------- pin 2
- | \| | |
- | | |
- | |\ | |
-SDA ----------x----x---| o---x--------------------------- pin 13
- | |/ |
- | |
- | /| |
- ---------o |----------------x-------------- pin 3
- \| | |
- | |
- --- ---
- | | | |
- |R| |R|
- | | | |
- --- ---
- | |
- ### ###
- GND GND
-
-Remarks:
- - This is the exact pinout and electronics used on the Analog Devices
- evaluation boards.
- /|
- - All inverters -o |- must be 74HC05, they must be open collector output.
- \|
- - All resitors are 10k.
- - Pins 18-25 of the parallel port connected to GND.
- - Pins 4-9 (D2-D7) could be used as VDD is the driver drives them high.
- The ADM1032 evaluation board uses D4-D7. Beware that the amount of
- current you can draw from the parallel port is limited. Also note that
- all connected lines MUST BE driven at the same state, else you'll short
- circuit the output buffers! So plugging the I2C adapter after loading
- the i2c-parport module might be a good safety since data line state
- prior to init may be unknown.
- - This is 5V!
- - Obviously you cannot read SCL (so it's not really standard-compliant).
- Pretty easy to add, just copy the SDA part and use another input pin.
- That would give (ELV compatible pinout):
-
-
-Device PC
-Side ______________________________Vdd (+) Side
- | | | |
- --- --- --- ---
- | | | | | | | |
- |R| |R| |R| |R|
- | | | | | | | |
- --- --- --- ---
- | | | |
- | | |\ | |
-SCL ----------x--------x--| o---x------------------------ pin 15
- | | |/ |
- | | |
- | | /| |
- | ---o |-------------x-------------- pin 2
- | \| | |
- | | |
- | | |
- | |\ | |
-SDA ---------------x---x--| o--------x------------------- pin 10
- | |/ |
- | |
- | /| |
- ---o |------------------x--------- pin 3
- \| | |
- | |
- --- ---
- | | | |
- |R| |R|
- | | | |
- --- ---
- | |
- ### ###
- GND GND
-
-
-If possible, you should use the same pinout configuration as existing
-adapters do, so you won't even have to change the code.
-
-
-Similar (but different) drivers
--------------------------------
-
-This driver is NOT the same as the i2c-pport driver found in the i2c
-package. The i2c-pport driver makes use of modern parallel port features so
-that you don't need additional electronics. It has other restrictions
-however, and was not ported to Linux 2.6 (yet).
-
-This driver is also NOT the same as the i2c-pcf-epp driver found in the
-lm_sensors package. The i2c-pcf-epp driver doesn't use the parallel port as
-an I2C bus directly. Instead, it uses it to control an external I2C bus
-master. That driver was not ported to Linux 2.6 (yet) either.
-
-
-Legacy documentation for Velleman adapter
------------------------------------------
-
-Useful links:
-Velleman http://www.velleman.be/
-Velleman K8000 Howto http://howto.htlw16.ac.at/k8000-howto.html
-
-The project has lead to new libs for the Velleman K8000 and K8005:
- LIBK8000 v1.99.1 and LIBK8005 v0.21
-With these libs, you can control the K8000 interface card and the K8005
-stepper motor card with the simple commands which are in the original
-Velleman software, like SetIOchannel, ReadADchannel, SendStepCCWFull and
-many more, using /dev/velleman.
- http://home.wanadoo.nl/hihihi/libk8000.htm
- http://home.wanadoo.nl/hihihi/libk8005.htm
- http://struyve.mine.nu:8080/index.php?block=k8000
- http://sourceforge.net/projects/libk8005/
-
-
-One For All JP1 parallel port adapter
--------------------------------------
-
-The JP1 project revolves around a set of remote controls which expose
-the I2C bus their internal configuration EEPROM lives on via a 6 pin
-jumper in the battery compartment. More details can be found at:
-
-http://www.hifi-remote.com/jp1/
-
-Details of the simple parallel port hardware can be found at:
-
-http://www.hifi-remote.com/jp1/hardware.shtml
+===============================
Kernel driver i2c-parport-light
+===============================
Author: Jean Delvare <jdelvare@suse.de>
-This driver is a light version of i2c-parport. It doesn't depend
+This driver is a light version of i2c-parport. It doesn't depend
on the parport driver, and uses direct I/O access instead. This might be
preferred on embedded systems where wasting memory for the clean but heavy
parport handling is not an option. The drawback is a reduced portability
-and the impossibility to daisy-chain other parallel port devices.
-
+and the impossibility to daisy-chain other parallel port devices.
+
Please see i2c-parport for documentation.
Module parameters:
--- /dev/null
+=========================
+Kernel driver i2c-parport
+=========================
+
+Author: Jean Delvare <jdelvare@suse.de>
+
+This is a unified driver for several i2c-over-parallel-port adapters,
+such as the ones made by Philips, Velleman or ELV. This driver is
+meant as a replacement for the older, individual drivers:
+
+ * i2c-philips-par
+ * i2c-elv
+ * i2c-velleman
+ * video/i2c-parport
+ (NOT the same as this one, dedicated to home brew teletext adapters)
+
+It currently supports the following devices:
+
+ * (type=0) Philips adapter
+ * (type=1) home brew teletext adapter
+ * (type=2) Velleman K8000 adapter
+ * (type=3) ELV adapter
+ * (type=4) Analog Devices ADM1032 evaluation board
+ * (type=5) Analog Devices evaluation boards: ADM1025, ADM1030, ADM1031
+ * (type=6) Barco LPT->DVI (K5800236) adapter
+ * (type=7) One For All JP1 parallel port adapter
+ * (type=8) VCT-jig
+
+These devices use different pinout configurations, so you have to tell
+the driver what you have, using the type module parameter. There is no
+way to autodetect the devices. Support for different pinout configurations
+can be easily added when needed.
+
+Earlier kernels defaulted to type=0 (Philips). But now, if the type
+parameter is missing, the driver will simply fail to initialize.
+
+SMBus alert support is available on adapters which have this line properly
+connected to the parallel port's interrupt pin.
+
+
+Building your own adapter
+-------------------------
+
+If you want to build you own i2c-over-parallel-port adapter, here is
+a sample electronics schema (credits go to Sylvain Munaut)::
+
+ Device PC
+ Side ___________________Vdd (+) Side
+ | | |
+ --- --- ---
+ | | | | | |
+ |R| |R| |R|
+ | | | | | |
+ --- --- ---
+ | | |
+ | | /| |
+ SCL ----------x--------o |-----------x------------------- pin 2
+ | \| | |
+ | | |
+ | |\ | |
+ SDA ----------x----x---| o---x--------------------------- pin 13
+ | |/ |
+ | |
+ | /| |
+ ---------o |----------------x-------------- pin 3
+ \| | |
+ | |
+ --- ---
+ | | | |
+ |R| |R|
+ | | | |
+ --- ---
+ | |
+ ### ###
+ GND GND
+
+Remarks:
+ - This is the exact pinout and electronics used on the Analog Devices
+ evaluation boards.
+ - All inverters::
+
+ /|
+ -o |-
+ \|
+
+ must be 74HC05, they must be open collector output.
+ - All resitors are 10k.
+ - Pins 18-25 of the parallel port connected to GND.
+ - Pins 4-9 (D2-D7) could be used as VDD is the driver drives them high.
+ The ADM1032 evaluation board uses D4-D7. Beware that the amount of
+ current you can draw from the parallel port is limited. Also note that
+ all connected lines MUST BE driven at the same state, else you'll short
+ circuit the output buffers! So plugging the I2C adapter after loading
+ the i2c-parport module might be a good safety since data line state
+ prior to init may be unknown.
+ - This is 5V!
+ - Obviously you cannot read SCL (so it's not really standard-compliant).
+ Pretty easy to add, just copy the SDA part and use another input pin.
+ That would give (ELV compatible pinout)::
+
+
+ Device PC
+ Side ______________________________Vdd (+) Side
+ | | | |
+ --- --- --- ---
+ | | | | | | | |
+ |R| |R| |R| |R|
+ | | | | | | | |
+ --- --- --- ---
+ | | | |
+ | | |\ | |
+ SCL ----------x--------x--| o---x------------------------ pin 15
+ | | |/ |
+ | | |
+ | | /| |
+ | ---o |-------------x-------------- pin 2
+ | \| | |
+ | | |
+ | | |
+ | |\ | |
+ SDA ---------------x---x--| o--------x------------------- pin 10
+ | |/ |
+ | |
+ | /| |
+ ---o |------------------x--------- pin 3
+ \| | |
+ | |
+ --- ---
+ | | | |
+ |R| |R|
+ | | | |
+ --- ---
+ | |
+ ### ###
+ GND GND
+
+
+If possible, you should use the same pinout configuration as existing
+adapters do, so you won't even have to change the code.
+
+
+Similar (but different) drivers
+-------------------------------
+
+This driver is NOT the same as the i2c-pport driver found in the i2c
+package. The i2c-pport driver makes use of modern parallel port features so
+that you don't need additional electronics. It has other restrictions
+however, and was not ported to Linux 2.6 (yet).
+
+This driver is also NOT the same as the i2c-pcf-epp driver found in the
+lm_sensors package. The i2c-pcf-epp driver doesn't use the parallel port as
+an I2C bus directly. Instead, it uses it to control an external I2C bus
+master. That driver was not ported to Linux 2.6 (yet) either.
+
+
+Legacy documentation for Velleman adapter
+-----------------------------------------
+
+Useful links:
+
+- Velleman http://www.velleman.be/
+- Velleman K8000 Howto http://howto.htlw16.ac.at/k8000-howto.html
+
+The project has lead to new libs for the Velleman K8000 and K8005:
+
+ LIBK8000 v1.99.1 and LIBK8005 v0.21
+
+With these libs, you can control the K8000 interface card and the K8005
+stepper motor card with the simple commands which are in the original
+Velleman software, like SetIOchannel, ReadADchannel, SendStepCCWFull and
+many more, using /dev/velleman.
+
+ - http://home.wanadoo.nl/hihihi/libk8000.htm
+ - http://home.wanadoo.nl/hihihi/libk8005.htm
+ - http://struyve.mine.nu:8080/index.php?block=k8000
+ - http://sourceforge.net/projects/libk8005/
+
+
+One For All JP1 parallel port adapter
+-------------------------------------
+
+The JP1 project revolves around a set of remote controls which expose
+the I2C bus their internal configuration EEPROM lives on via a 6 pin
+jumper in the battery compartment. More details can be found at:
+
+http://www.hifi-remote.com/jp1/
+
+Details of the simple parallel port hardware can be found at:
+
+http://www.hifi-remote.com/jp1/hardware.shtml
+=========================
Kernel driver i2c-pca-isa
+=========================
Supported adapters:
+
This driver supports ISA boards using the Philips PCA 9564
Parallel bus to I2C bus controller
-----------------
* base int
- I/O base address
+ I/O base address
* irq int
- IRQ interrupt
+ IRQ interrupt
* clock int
- Clock rate as described in table 1 of PCA9564 datasheet
+ Clock rate as described in table 1 of PCA9564 datasheet
Description
-----------
+=======================
Kernel driver i2c-piix4
+=======================
Supported adapters:
* Intel 82371AB PIIX4 and PIIX4E
* Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge
Datasheet: Publicly available at the SMSC website http://www.smsc.com
-Authors:
- Frodo Looijaard <frodol@dds.nl>
- Philip Edelbrock <phil@netroedge.com>
+Authors:
+ - Frodo Looijaard <frodol@dds.nl>
+
- Philip Edelbrock <phil@netroedge.com>
Module Parameters
The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of
functionality. Among other things, it implements the PCI bus. One of its
-minor functions is implementing a System Management Bus. This is a true
+minor functions is implementing a System Management Bus. This is a true
SMBus - you can not access it on I2C levels. The good news is that it
natively understands SMBus commands and you do not have to worry about
timing problems. The bad news is that non-SMBus devices connected to it can
confuse it mightily. Yes, this is known to happen...
-Do 'lspci -v' and see whether it contains an entry like this:
+Do ``lspci -v`` and see whether it contains an entry like this::
-0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02)
- Flags: medium devsel, IRQ 9
+ 0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02)
+ Flags: medium devsel, IRQ 9
Bus and device numbers may differ, but the function number must be
identical (like many PCI devices, the PIIX4 incorporates a number of
device is located at 00:0f.0.
2) Now you just need to change the value in 0xD2 register. Get it first with
command: lspci -xxx -s 00:0f.0
- If the value is 0x3 then you need to change it to 0x1
+ If the value is 0x3 then you need to change it to 0x1:
setpci -s 00:0f.0 d2.b=1
Please note that you don't need to do that in all cases, just when the SMBus is
+=========================
Kernel driver i2c-sis5595
+=========================
Authors:
- Frodo Looijaard <frodol@dds.nl>,
- Mark D. Studebaker <mdsxyz123@yahoo.com>,
- Philip Edelbrock <phil@netroedge.com>
+ - Frodo Looijaard <frodol@dds.nl>,
+ - Mark D. Studebaker <mdsxyz123@yahoo.com>,
+
- Philip Edelbrock <phil@netroedge.com>
Supported adapters:
* Silicon Integrated Systems Corp. SiS5595 Southbridge
Note: all have mfr. ID 0x1039.
+ ========= ======
SUPPORTED PCI ID
+ ========= ======
5595 0008
+ ========= ======
Note: these chips contain a 0008 device which is incompatible with the
5595. We recognize these by the presence of the listed
"blacklist" PCI ID and refuse to load.
+ ============= ====== ================
NOT SUPPORTED PCI ID BLACKLIST PCI ID
+ ============= ====== ================
540 0008 0540
550 0008 0550
5513 0008 5511
735 0008 0735
745 0008 0745
746 0008 0746
+ ============= ====== ================
Module Parameters
-----------------
-* force_addr=0xaddr Set the I/O base address. Useful for boards
+================== =====================================================
+force_addr=0xaddr Set the I/O base address. Useful for boards
that don't set the address in the BIOS. Does not do a
PCI force; the device must still be present in lspci.
Don't use this unless the driver complains that the
base address is not set.
+================== =====================================================
Description
-----------
chip, you want the sis5595 driver for those, not this driver. This driver
is a BUS driver, not a CHIP driver. A BUS driver is used by other CHIP
drivers to access chips on the bus.
-
+++ /dev/null
-Kernel driver i2c-sis630
-
-Supported adapters:
- * Silicon Integrated Systems Corp (SiS)
- 630 chipset (Datasheet: available at http://www.sfr-fresh.com/linux)
- 730 chipset
- 964 chipset
- * Possible other SiS chipsets ?
-
-Author: Alexander Malysh <amalysh@web.de>
- Amaury Decrême <amaury.decreme@gmail.com> - SiS964 support
-
-Module Parameters
------------------
-
-* force = [1|0] Forcibly enable the SIS630. DANGEROUS!
- This can be interesting for chipsets not named
- above to check if it works for you chipset, but DANGEROUS!
-
-* high_clock = [1|0] Forcibly set Host Master Clock to 56KHz (default,
- what your BIOS use). DANGEROUS! This should be a bit
- faster, but freeze some systems (i.e. my Laptop).
- SIS630/730 chip only.
-
-
-Description
------------
-
-This SMBus only driver is known to work on motherboards with the above
-named chipsets.
-
-If you see something like this:
-
-00:00.0 Host bridge: Silicon Integrated Systems [SiS] 630 Host (rev 31)
-00:01.0 ISA bridge: Silicon Integrated Systems [SiS] 85C503/5513
-
-or like this:
-
-00:00.0 Host bridge: Silicon Integrated Systems [SiS] 730 Host (rev 02)
-00:01.0 ISA bridge: Silicon Integrated Systems [SiS] 85C503/5513
-
-or like this:
-
-00:00.0 Host bridge: Silicon Integrated Systems [SiS] 760/M760 Host (rev 02)
-00:02.0 ISA bridge: Silicon Integrated Systems [SiS] SiS964 [MuTIOL Media IO]
- LPC Controller (rev 36)
-
-in your 'lspci' output , then this driver is for your chipset.
-
-Thank You
----------
-Philip Edelbrock <phil@netroedge.com>
-- testing SiS730 support
-Mark M. Hoffman <mhoffman@lightlink.com>
-- bug fixes
-
-To anyone else which I forgot here ;), thanks!
-
--- /dev/null
+========================
+Kernel driver i2c-sis630
+========================
+
+Supported adapters:
+ * Silicon Integrated Systems Corp (SiS)
+ 630 chipset (Datasheet: available at http://www.sfr-fresh.com/linux)
+ 730 chipset
+ 964 chipset
+ * Possible other SiS chipsets ?
+
+Author:
+ - Alexander Malysh <amalysh@web.de>
+ - Amaury Decrême <amaury.decreme@gmail.com> - SiS964 support
+
+Module Parameters
+-----------------
+
+================== =====================================================
+force = [1|0] Forcibly enable the SIS630. DANGEROUS!
+ This can be interesting for chipsets not named
+ above to check if it works for you chipset,
+ but DANGEROUS!
+
+high_clock = [1|0] Forcibly set Host Master Clock to 56KHz (default,
+ what your BIOS use). DANGEROUS! This should be a bit
+ faster, but freeze some systems (i.e. my Laptop).
+ SIS630/730 chip only.
+================== =====================================================
+
+
+Description
+-----------
+
+This SMBus only driver is known to work on motherboards with the above
+named chipsets.
+
+If you see something like this::
+
+ 00:00.0 Host bridge: Silicon Integrated Systems [SiS] 630 Host (rev 31)
+ 00:01.0 ISA bridge: Silicon Integrated Systems [SiS] 85C503/5513
+
+or like this::
+
+ 00:00.0 Host bridge: Silicon Integrated Systems [SiS] 730 Host (rev 02)
+ 00:01.0 ISA bridge: Silicon Integrated Systems [SiS] 85C503/5513
+
+or like this::
+
+ 00:00.0 Host bridge: Silicon Integrated Systems [SiS] 760/M760 Host (rev 02)
+ 00:02.0 ISA bridge: Silicon Integrated Systems [SiS] SiS964 [MuTIOL Media IO]
+ LPC Controller (rev 36)
+
+in your ``lspci`` output , then this driver is for your chipset.
+
+Thank You
+---------
+Philip Edelbrock <phil@netroedge.com>
+- testing SiS730 support
+Mark M. Hoffman <mhoffman@lightlink.com>
+- bug fixes
+
+To anyone else which I forgot here ;), thanks!
+========================
Kernel driver i2c-sis96x
+========================
Replaces 2.4.x i2c-sis645
Supported adapters:
+
* Silicon Integrated Systems Corp (SiS)
+
Any combination of these host bridges:
645, 645DX (aka 646), 648, 650, 651, 655, 735, 745, 746
+
and these south bridges:
- 961, 962, 963(L)
+ 961, 962, 963(L)
Author: Mark M. Hoffman <mhoffman@lightlink.com>
place. Thanks to Alexander Malysh <amalysh@web.de> for providing the
SiS630 datasheet (and driver).
-The command "lspci" as root should produce something like these lines:
+The command ``lspci`` as root should produce something like these lines::
-00:00.0 Host bridge: Silicon Integrated Systems [SiS]: Unknown device 0645
-00:02.0 ISA bridge: Silicon Integrated Systems [SiS] 85C503/5513
-00:02.1 SMBus: Silicon Integrated Systems [SiS]: Unknown device 0016
+ 00:00.0 Host bridge: Silicon Integrated Systems [SiS]: Unknown device 0645
+ 00:02.0 ISA bridge: Silicon Integrated Systems [SiS] 85C503/5513
+ 00:02.1 SMBus: Silicon Integrated Systems [SiS]: Unknown device 0016
-or perhaps this...
+or perhaps this::
-00:00.0 Host bridge: Silicon Integrated Systems [SiS]: Unknown device 0645
-00:02.0 ISA bridge: Silicon Integrated Systems [SiS]: Unknown device 0961
-00:02.1 SMBus: Silicon Integrated Systems [SiS]: Unknown device 0016
+ 00:00.0 Host bridge: Silicon Integrated Systems [SiS]: Unknown device 0645
+ 00:02.0 ISA bridge: Silicon Integrated Systems [SiS]: Unknown device 0961
+ 00:02.1 SMBus: Silicon Integrated Systems [SiS]: Unknown device 0016
(kernel versions later than 2.4.18 may fill in the "Unknown"s)
------
* The driver does not support SMBus block reads/writes; I may add them if a
-scenario is found where they're needed.
+ scenario is found where they're needed.
Thank You
Mark D. Studebaker <mdsxyz123@yahoo.com>
- design hints and bug fixes
+
Alexander Maylsh <amalysh@web.de>
- ditto, plus an important datasheet... almost the one I really wanted
+
Hans-Günter Lütke Uphues <hg_lu@t-online.de>
- patch for SiS735
+
Robert Zwerus <arzie@dds.nl>
- testing for SiS645DX
+
Kianusch Sayah Karadji <kianusch@sk-tech.net>
- patch for SiS645DX/962
+
Ken Healy
- patch for SiS655
To anyone else who has written w/ feedback, thanks!
-
+==========================
Kernel driver i2c-taos-evm
+==========================
Author: Jean Delvare <jdelvare@suse.de>
In order to use this driver, you'll need the serport driver, and the
inputattach tool, which is part of the input-utils package. The following
commands will tell the kernel that you have a TAOS EVM on the first
-serial port:
+serial port::
-# modprobe serport
-# inputattach --taos-evm /dev/ttyS0
+ # modprobe serport
+ # inputattach --taos-evm /dev/ttyS0
Technical details
+=====================
Kernel driver i2c-via
+=====================
Supported adapters:
* VIA Technologies, InC. VT82C586B
i2c-via is an i2c bus driver for motherboards with VIA chipset.
The following VIA pci chipsets are supported:
- - MVP3, VP3, VP2/97, VPX/97
+ - MVP3, VP3, VP2/97, VPX/97
- others with South bridge VT82C586B
-Your lspci listing must show this :
+Your ``lspci`` listing must show this ::
Bridge: VIA Technologies, Inc. VT82C586B ACPI (rev 10)
- Problems?
-
- Q: You have VT82C586B on the motherboard, but not in the listing.
-
- A: Go to your BIOS setup, section PCI devices or similar.
- Turn USB support on, and try again.
+Problems?
+---------
- Q: No error messages, but still i2c doesn't seem to work.
+ Q:
+ You have VT82C586B on the motherboard, but not in the listing.
- A: This can happen. This driver uses the pins VIA recommends in their
+ A:
+ Go to your BIOS setup, section PCI devices or similar.
+ Turn USB support on, and try again.
+
+ Q:
+ No error messages, but still i2c doesn't seem to work.
+
+ A:
+ This can happen. This driver uses the pins VIA recommends in their
datasheets, but there are several ways the motherboard manufacturer
can actually wire the lines.
-
+========================
Kernel driver i2c-viapro
+========================
Supported adapters:
* VIA Technologies, Inc. VT82C596A/B
Datasheet: available on http://linux.via.com.tw
Authors:
- Kyösti Mälkki <kmalkki@cc.hut.fi>,
- Mark D. Studebaker <mdsxyz123@yahoo.com>,
- Jean Delvare <jdelvare@suse.de>
+ - Kyösti Mälkki <kmalkki@cc.hut.fi>,
+ - Mark D. Studebaker <mdsxyz123@yahoo.com>,
+ - Jean Delvare <jdelvare@suse.de>
Module Parameters
-----------------
i2c-viapro is a true SMBus host driver for motherboards with one of the
supported VIA south bridges.
-Your lspci -n listing must show one of these :
+Your ``lspci -n`` listing must show one of these :
+ ================ ======================
device 1106:3050 (VT82C596A function 3)
device 1106:3051 (VT82C596B function 3)
device 1106:3057 (VT82C686 function 4)
device 1106:8353 (VX800/VX820)
device 1106:8409 (VX855/VX875)
device 1106:8410 (VX900)
+ ================ ======================
If none of these show up, you should look in the BIOS for settings like
enable ACPI / SMBus or even USB.
--- /dev/null
+. SPDX-License-Identifier: GPL-2.0
+
+===============
+I2C Bus Drivers
+===============
+
+.. toctree::
+ :maxdepth: 1
+
+ i2c-ali1535
+ i2c-ali1563
+ i2c-ali15x3
+ i2c-amd756
+ i2c-amd8111
+ i2c-amd-mp2
+ i2c-diolan-u2c
+ i2c-i801
+ i2c-ismt
+ i2c-mlxcpld
+ i2c-nforce2
+ i2c-nvidia-gpu
+ i2c-ocores
+ i2c-parport-light
+ i2c-parport
+ i2c-pca-isa
+ i2c-piix4
+ i2c-sis5595
+ i2c-sis630
+ i2c-sis96x
+ i2c-taos-evm
+ i2c-viapro
+ i2c-via
+ scx200_acb
+========================
Kernel driver scx200_acb
+========================
Author: Christer Weinigel <wingel@nano-system.com>
The SC1100 WRAP boards are known to use base addresses 0x810 and 0x820.
If the scx200_acb driver is built into the kernel, add the following
-parameter to your boot command line:
+parameter to your boot command line::
+
scx200_acb.base=0x810,0x820
+
If the scx200_acb driver is built as a module, add the following line to
-a configuration file in /etc/modprobe.d/ instead:
+a configuration file in /etc/modprobe.d/ instead::
+
options scx200_acb base=0x810,0x820
+====================
+I2C Device Interface
+====================
+
Usually, i2c devices are controlled by a kernel driver. But it is also
possible to access all devices on an adapter from userspace, through
the /dev interface. You need to load module i2c-dev for this.
=========
So let's say you want to access an i2c adapter from a C program.
-First, you need to include these two headers:
+First, you need to include these two headers::
#include <linux/i2c-dev.h>
#include <i2c/smbus.h>
Adapter numbers are assigned somewhat dynamically, so you can not
assume much about them. They can even change from one boot to the next.
-Next thing, open the device file, as follows:
+Next thing, open the device file, as follows::
int file;
int adapter_nr = 2; /* probably dynamically determined */
}
When you have opened the device, you must specify with what device
-address you want to communicate:
+address you want to communicate::
int addr = 0x40; /* The I2C address */
Well, you are all set up now. You can now use SMBus commands or plain
I2C to communicate with your device. SMBus commands are preferred if
-the device supports them. Both are illustrated below.
+the device supports them. Both are illustrated below::
__u8 reg = 0x10; /* Device register to access */
__s32 res;
The following IOCTLs are defined:
-ioctl(file, I2C_SLAVE, long addr)
+``ioctl(file, I2C_SLAVE, long addr)``
Change slave address. The address is passed in the 7 lower bits of the
argument (except for 10 bit addresses, passed in the 10 lower bits in this
case).
-ioctl(file, I2C_TENBIT, long select)
+``ioctl(file, I2C_TENBIT, long select)``
Selects ten bit addresses if select not equals 0, selects normal 7 bit
addresses if select equals 0. Default 0. This request is only valid
if the adapter has I2C_FUNC_10BIT_ADDR.
-ioctl(file, I2C_PEC, long select)
+``ioctl(file, I2C_PEC, long select)``
Selects SMBus PEC (packet error checking) generation and verification
if select not equals 0, disables if select equals 0. Default 0.
Used only for SMBus transactions. This request only has an effect if the
the adapter has I2C_FUNC_SMBUS_PEC; it is still safe if not, it just
doesn't have any effect.
-ioctl(file, I2C_FUNCS, unsigned long *funcs)
- Gets the adapter functionality and puts it in *funcs.
+``ioctl(file, I2C_FUNCS, unsigned long *funcs)``
+ Gets the adapter functionality and puts it in ``*funcs``.
-ioctl(file, I2C_RDWR, struct i2c_rdwr_ioctl_data *msgset)
+``ioctl(file, I2C_RDWR, struct i2c_rdwr_ioctl_data *msgset)``
Do combined read/write transaction without stop in between.
Only valid if the adapter has I2C_FUNC_I2C. The argument is
- a pointer to a
+ a pointer to a::
- struct i2c_rdwr_ioctl_data {
+ struct i2c_rdwr_ioctl_data {
struct i2c_msg *msgs; /* ptr to array of simple messages */
int nmsgs; /* number of messages to exchange */
- }
+ }
The msgs[] themselves contain further pointers into data buffers.
The function will write or read data to or from that buffers depending
The slave address and whether to use ten bit address mode has to be
set in each message, overriding the values set with the above ioctl's.
-ioctl(file, I2C_SMBUS, struct i2c_smbus_ioctl_data *args)
- If possible, use the provided i2c_smbus_* methods described below instead
+``ioctl(file, I2C_SMBUS, struct i2c_smbus_ioctl_data *args)``
+ If possible, use the provided ``i2c_smbus_*`` methods described below instead
of issuing direct ioctls.
You can do plain i2c transactions by using read(2) and write(2) calls.
ioctl I2C_SLAVE before you try to access the device.
You can do SMBus level transactions (see documentation file smbus-protocol
-for details) through the following functions:
+for details) through the following functions::
+
__s32 i2c_smbus_write_quick(int file, __u8 value);
__s32 i2c_smbus_read_byte(int file);
__s32 i2c_smbus_write_byte(int file, __u8 value);
__s32 i2c_smbus_read_block_data(int file, __u8 command, __u8 *values);
__s32 i2c_smbus_write_block_data(int file, __u8 command, __u8 length,
__u8 *values);
+
All these transactions return -1 on failure; you can read errno to see
what happened. The 'write' transactions return 0 on success; the
'read' transactions return the read value, except for read_block, which
For the interested, here's the code flow which happens inside the kernel
when you use the /dev interface to I2C:
-1* Your program opens /dev/i2c-N and calls ioctl() on it, as described in
-section "C example" above.
-
-2* These open() and ioctl() calls are handled by the i2c-dev kernel
-driver: see i2c-dev.c:i2cdev_open() and i2c-dev.c:i2cdev_ioctl(),
-respectively. You can think of i2c-dev as a generic I2C chip driver
-that can be programmed from user-space.
-
-3* Some ioctl() calls are for administrative tasks and are handled by
-i2c-dev directly. Examples include I2C_SLAVE (set the address of the
-device you want to access) and I2C_PEC (enable or disable SMBus error
-checking on future transactions.)
-
-4* Other ioctl() calls are converted to in-kernel function calls by
-i2c-dev. Examples include I2C_FUNCS, which queries the I2C adapter
-functionality using i2c.h:i2c_get_functionality(), and I2C_SMBUS, which
-performs an SMBus transaction using i2c-core-smbus.c:i2c_smbus_xfer().
-
-The i2c-dev driver is responsible for checking all the parameters that
-come from user-space for validity. After this point, there is no
-difference between these calls that came from user-space through i2c-dev
-and calls that would have been performed by kernel I2C chip drivers
-directly. This means that I2C bus drivers don't need to implement
-anything special to support access from user-space.
-
-5* These i2c.h functions are wrappers to the actual implementation of
-your I2C bus driver. Each adapter must declare callback functions
-implementing these standard calls. i2c.h:i2c_get_functionality() calls
-i2c_adapter.algo->functionality(), while
-i2c-core-smbus.c:i2c_smbus_xfer() calls either
-adapter.algo->smbus_xfer() if it is implemented, or if not,
-i2c-core-smbus.c:i2c_smbus_xfer_emulated() which in turn calls
-i2c_adapter.algo->master_xfer().
+1) Your program opens /dev/i2c-N and calls ioctl() on it, as described in
+ section "C example" above.
+
+2) These open() and ioctl() calls are handled by the i2c-dev kernel
+ driver: see i2c-dev.c:i2cdev_open() and i2c-dev.c:i2cdev_ioctl(),
+ respectively. You can think of i2c-dev as a generic I2C chip driver
+ that can be programmed from user-space.
+
+3) Some ioctl() calls are for administrative tasks and are handled by
+ i2c-dev directly. Examples include I2C_SLAVE (set the address of the
+ device you want to access) and I2C_PEC (enable or disable SMBus error
+ checking on future transactions.)
+
+4) Other ioctl() calls are converted to in-kernel function calls by
+ i2c-dev. Examples include I2C_FUNCS, which queries the I2C adapter
+ functionality using i2c.h:i2c_get_functionality(), and I2C_SMBUS, which
+ performs an SMBus transaction using i2c-core-smbus.c:i2c_smbus_xfer().
+
+ The i2c-dev driver is responsible for checking all the parameters that
+ come from user-space for validity. After this point, there is no
+ difference between these calls that came from user-space through i2c-dev
+ and calls that would have been performed by kernel I2C chip drivers
+ directly. This means that I2C bus drivers don't need to implement
+ anything special to support access from user-space.
+
+5) These i2c.h functions are wrappers to the actual implementation of
+ your I2C bus driver. Each adapter must declare callback functions
+ implementing these standard calls. i2c.h:i2c_get_functionality() calls
+ i2c_adapter.algo->functionality(), while
+ i2c-core-smbus.c:i2c_smbus_xfer() calls either
+ adapter.algo->smbus_xfer() if it is implemented, or if not,
+ i2c-core-smbus.c:i2c_smbus_xfer_emulated() which in turn calls
+ i2c_adapter.algo->master_xfer().
After your I2C bus driver has processed these requests, execution runs
up the call chain, with almost no processing done, except by i2c-dev to
+=====================
+I2C/SMBUS Fault Codes
+=====================
+
This is a summary of the most important conventions for use of fault
codes in the I2C/SMBus stack.
when a slave stretches clocks too far. I2C has no such
timeouts, but it's normal for I2C adapters to impose some
arbitrary limits (much longer than SMBus!) too.
-
+=======================
+I2C/SMBus Functionality
+=======================
+
INTRODUCTION
------------
-Because not every I2C or SMBus adapter implements everything in the
+Because not every I2C or SMBus adapter implements everything in the
I2C specifications, a client can not trust that everything it needs
is implemented when it is given the option to attach to an adapter:
the client needs some way to check whether an adapter has the needed
-functionality.
+functionality.
FUNCTIONALITY CONSTANTS
For the most up-to-date list of functionality constants, please check
<uapi/linux/i2c.h>!
+ =============================== ==============================================
I2C_FUNC_I2C Plain i2c-level commands (Pure SMBus
adapters typically can not do these)
I2C_FUNC_10BIT_ADDR Handles the 10-bit address extensions
I2C_FUNC_SMBUS_WRITE_BLOCK_DATA Handles the SMBus write_block_data command
I2C_FUNC_SMBUS_READ_I2C_BLOCK Handles the SMBus read_i2c_block_data command
I2C_FUNC_SMBUS_WRITE_I2C_BLOCK Handles the SMBus write_i2c_block_data command
+ =============================== ==============================================
A few combinations of the above flags are also defined for your convenience:
+ ========================= ======================================
I2C_FUNC_SMBUS_BYTE Handles the SMBus read_byte
and write_byte commands
I2C_FUNC_SMBUS_BYTE_DATA Handles the SMBus read_byte_data
I2C_FUNC_SMBUS_EMUL Handles all SMBus commands that can be
emulated by a real I2C adapter (using
the transparent emulation layer)
+ ========================= ======================================
In kernel versions prior to 3.5 I2C_FUNC_NOSTART was implemented as
part of I2C_FUNC_PROTOCOL_MANGLING.
----------------------
When you write a new adapter driver, you will have to implement a
-function callback `functionality'. Typical implementations are given
+function callback ``functionality``. Typical implementations are given
below.
A typical SMBus-only adapter would list all the SMBus transactions it
-supports. This example comes from the i2c-piix4 driver:
+supports. This example comes from the i2c-piix4 driver::
static u32 piix4_func(struct i2c_adapter *adapter)
{
}
A typical full-I2C adapter would use the following (from the i2c-pxa
-driver):
+driver)::
static u32 i2c_pxa_functionality(struct i2c_adapter *adap)
{
Before a client tries to attach to an adapter, or even do tests to check
whether one of the devices it supports is present on an adapter, it should
check whether the needed functionality is present. The typical way to do
-this is (from the lm75 driver):
+this is (from the lm75 driver)::
static int lm75_detect(...)
{
to use the /dev interface. You will still have to check whether the
functionality you need is supported, of course. This is done using
the I2C_FUNCS ioctl. An example, adapted from the i2cdetect program, is
-below:
+below::
int file;
if (file = open("/dev/i2c-0", O_RDWR) < 0) {
should be detected beforehand. Also note, that SCL going down is monitored
using interrupts, so the interrupt latency might cause the first bits to be not
corrupted. A good starting point for using this fault injector on an otherwise
-idle bus is:
+idle bus is::
-# echo 200 > lose_arbitration &
-# i2cget -y <bus_to_test> 0x3f
+ # echo 200 > lose_arbitration &
+ # i2cget -y <bus_to_test> 0x3f
Panic during transfer
=====================
process is interruptible, though.
Start of a transfer is detected by waiting for SCL going down by the master
-under test. A good starting point for using this fault injector is:
+under test. A good starting point for using this fault injector is::
-# echo 0 > inject_panic &
-# i2cget -y <bus_to_test> <some_address>
+ # echo 0 > inject_panic &
+ # i2cget -y <bus_to_test> <some_address>
Note that there doesn't need to be a device listening to the address you are
using. Results may vary depending on that, though.
+============
+I2C Protocol
+============
+
This document describes the i2c protocol. Or will, when it is finished :-)
Key to symbols
==============
+=============== =============================================================
S (1 bit) : Start bit
P (1 bit) : Stop bit
Rd/Wr (1 bit) : Read/Write bit. Rd equals 1, Wr equals 0.
for 16 bit data.
Count (8 bits): A data byte containing the length of a block operation.
-[..]: Data sent by I2C device, as opposed to data sent by the host adapter.
+[..]: Data sent by I2C device, as opposed to data sent by the
+ host adapter.
+=============== =============================================================
Simple send transaction
-======================
+=======================
-This corresponds to i2c_master_send.
+This corresponds to i2c_master_send::
S Addr Wr [A] Data [A] Data [A] ... [A] Data [A] P
Simple receive transaction
-===========================
+==========================
-This corresponds to i2c_master_recv
+This corresponds to i2c_master_recv::
S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
Combined transactions
-====================
+=====================
This corresponds to i2c_transfer
They are just like the above transactions, but instead of a stop bit P
a start bit S is sent and the transaction continues. An example of
-a byte read, followed by a byte write:
+a byte read, followed by a byte write::
S Addr Rd [A] [Data] NA S Addr Wr [A] Data [A] P
I2C_M_NOSTART:
In a combined transaction, no 'S Addr Wr/Rd [A]' is generated at some
point. For example, setting I2C_M_NOSTART on the second partial message
- generates something like:
+ generates something like::
+
S Addr Rd [A] [Data] NA Data [A] P
+
If you set the I2C_M_NOSTART variable for the first partial message,
we do not generate Addr, but we do generate the startbit S. This will
probably confuse all other clients on your bus, so don't try this.
I2C_M_REV_DIR_ADDR:
This toggles the Rd/Wr flag. That is, if you want to do a write, but
need to emit an Rd instead of a Wr, or vice versa, you set this
- flag. For example:
+ flag. For example::
+
S Addr Rd [A] Data [A] Data [A] ... [A] Data [A] P
I2C_M_STOP:
-MODULE: i2c-stub
+========
+i2c-stub
+========
-DESCRIPTION:
+Description
+===========
This module is a very simple fake I2C/SMBus driver. It implements six
types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, (r/w)
return the number of bytes selected with the largest write so far.
The typical use-case is like this:
+
1. load this module
2. use i2cset (from the i2c-tools project) to pre-load some data
3. load the target chip driver module
There's a script named i2c-stub-from-dump in the i2c-tools package which
can load register values automatically from a chip dump.
-PARAMETERS:
+Parameters
+==========
int chip_addr[10]:
The SMBus addresses to emulate chips at.
value 0x1f0000 would only enable the quick, byte and byte data
commands.
-u8 bank_reg[10]
-u8 bank_mask[10]
-u8 bank_start[10]
-u8 bank_end[10]:
+u8 bank_reg[10], u8 bank_mask[10], u8 bank_start[10], u8 bank_end[10]:
Optional bank settings. They tell which bits in which register
select the active bank, as well as the range of banked registers.
-CAVEATS:
+Caveats
+=======
If your target driver polls some byte or word waiting for it to change, the
stub could lock it up. Use i2cset to unlock it.
If you spam it hard enough, printk can be lossy. This module really wants
something like relayfs.
-
+============
I2C topology
============
that has to be operated before the device can be accessed.
Etc
+===
These constructs are represented as i2c adapter trees by Linux, where
each adapter has a parent adapter (except the root adapter) and zero or
useful to know if a mux is mux-locked or if it is parent-locked. The
following list was correct at the time of writing:
-In drivers/i2c/muxes/
+In drivers/i2c/muxes/:
+
+====================== =============================================
i2c-arb-gpio-challenge Parent-locked
i2c-mux-gpio Normally parent-locked, mux-locked iff
all involved gpio pins are controlled by the
all involved pinctrl devices are controlled
by the same i2c root adapter that they mux.
i2c-mux-reg Parent-locked
+====================== =============================================
+
+In drivers/iio/:
-In drivers/iio/
+====================== =============================================
gyro/mpu3050 Mux-locked
imu/inv_mpu6050/ Mux-locked
+====================== =============================================
-In drivers/media/
+In drivers/media/:
+
+======================= =============================================
dvb-frontends/lgdt3306a Mux-locked
dvb-frontends/m88ds3103 Parent-locked
dvb-frontends/rtl2830 Parent-locked
dvb-frontends/rtl2832 Mux-locked
dvb-frontends/si2168 Mux-locked
usb/cx231xx/ Parent-locked
+======================= =============================================
Mux-locked muxes
stages of the transaction. This has the benefit that the mux driver
may be easier and cleaner to implement, but it has some caveats.
+==== =====================================================================
ML1. If you build a topology with a mux-locked mux being the parent
of a parent-locked mux, this might break the expectation from the
parent-locked mux that the root adapter is locked during the
Otherwise garbage may appear on the bus as seen from devices
behind the mux, when an unrelated i2c transfer is in flight during
the non-i2c mux-changing operation.
+==== =====================================================================
Mux-locked Example
------------------
+
+::
+
.----------. .--------.
.--------. | mux- |-----| dev D1 |
| root |--+--| locked | '--------'
__i2c_transfer), or a deadlock will follow. There are a couple of
caveats.
+==== ====================================================================
PL1. If you build a topology with a parent-locked mux being the child
of another mux, this might break a possible assumption from the
child mux that the root adapter is unused between its select op
caused by these subsystems are unlocked. This can be convoluted to
accomplish, maybe even impossible if an acceptably clean solution
is sought.
+==== ====================================================================
Parent-locked Example
---------------------
+::
+
.----------. .--------.
.--------. | parent- |-----| dev D1 |
| root |--+--| locked | '--------'
When there is an access to D1, this happens:
- 1. Someone issues an i2c-transfer to D1.
- 2. M1 locks muxes on its parent (the root adapter in this case).
- 3. M1 locks its parent adapter.
- 4. M1 calls ->select to ready the mux.
- 5. If M1 does any i2c-transfers (on this root adapter) as part of
- its select, those transfers must be unlocked i2c-transfers so
- that they do not deadlock the root adapter.
- 6. M1 feeds the i2c-transfer from step 1 to the root adapter as an
- unlocked i2c-transfer, so that it does not deadlock the parent
- adapter.
- 7. M1 calls ->deselect, if it has one.
- 8. Same rules as in step 5, but for ->deselect.
- 9. M1 unlocks its parent adapter.
-10. M1 unlocks muxes on its parent.
+ 1. Someone issues an i2c-transfer to D1.
+ 2. M1 locks muxes on its parent (the root adapter in this case).
+ 3. M1 locks its parent adapter.
+ 4. M1 calls ->select to ready the mux.
+ 5. If M1 does any i2c-transfers (on this root adapter) as part of
+ its select, those transfers must be unlocked i2c-transfers so
+ that they do not deadlock the root adapter.
+ 6. M1 feeds the i2c-transfer from step 1 to the root adapter as an
+ unlocked i2c-transfer, so that it does not deadlock the parent
+ adapter.
+ 7. M1 calls ->deselect, if it has one.
+ 8. Same rules as in step 5, but for ->deselect.
+ 9. M1 unlocks its parent adapter.
+ 10. M1 unlocks muxes on its parent.
This means that accesses to both D2 and D3 are locked out for the full
Parent-locked mux as parent of parent-locked mux
------------------------------------------------
-This is a useful topology, but it can be bad.
+This is a useful topology, but it can be bad::
.----------. .----------. .--------.
.--------. | parent- |-----| parent- |-----| dev D1 |
Mux-locked mux as parent of mux-locked mux
------------------------------------------
-This is a good topology.
+This is a good topology::
.----------. .----------. .--------.
.--------. | mux- |-----| mux- |-----| dev D1 |
Mux-locked mux as parent of parent-locked mux
---------------------------------------------
-This is probably a bad topology.
+This is probably a bad topology::
.----------. .----------. .--------.
.--------. | mux- |-----| parent- |-----| dev D1 |
Parent-locked mux as parent of mux-locked mux
---------------------------------------------
-This is a good topology.
+This is a good topology::
.----------. .----------. .--------.
.--------. | parent- |-----| mux- |-----| dev D1 |
Two mux-locked sibling muxes
----------------------------
-This is a good topology.
+This is a good topology::
.--------.
.----------. .--| dev D1 |
Two parent-locked sibling muxes
-------------------------------
-This is a good topology.
+This is a good topology::
.--------.
.----------. .--| dev D1 |
Mux-locked and parent-locked sibling muxes
------------------------------------------
-This is a good topology.
+This is a good topology::
.--------.
.----------. .--| dev D1 |
--- /dev/null
+. SPDX-License-Identifier: GPL-2.0
+
+===================
+I2C/SMBus Subsystem
+===================
+
+.. toctree::
+ :maxdepth: 1
+
+ dev-interface
+ dma-considerations
+ fault-codes
+ functionality
+ gpio-fault-injection
+ i2c-protocol
+ i2c-stub
+ i2c-topology
+ instantiating-devices
+ old-module-parameters
+ slave-eeprom-backend
+ slave-interface
+ smbus-protocol
+ summary
+ ten-bit-addresses
+ upgrading-clients
+ writing-clients
+
+ muxes/i2c-mux-gpio
+
+ busses/index
+
+.. only:: subproject and html
+
+ Indices
+ =======
+
+ * :ref:`genindex`
+==============================
How to instantiate I2C devices
==============================
devices which live on this bus. This is done with an array of struct
i2c_board_info which is registered by calling i2c_register_board_info().
-Example (from omap2 h4):
+Example (from omap2 h4)::
-static struct i2c_board_info h4_i2c_board_info[] __initdata = {
+ static struct i2c_board_info h4_i2c_board_info[] __initdata = {
{
I2C_BOARD_INFO("isp1301_omap", 0x2d),
.irq = OMAP_GPIO_IRQ(125),
I2C_BOARD_INFO("24c01", 0x57),
.platform_data = &m24c01,
},
-};
+ };
-static void __init omap_h4_init(void)
-{
+ static void __init omap_h4_init(void)
+ {
(...)
i2c_register_board_info(1, h4_i2c_board_info,
ARRAY_SIZE(h4_i2c_board_info));
(...)
-}
+ }
The above code declares 3 devices on I2C bus 1, including their respective
addresses and custom data needed by their drivers. When the I2C bus in
This method has the same implications as method 1a. The declaration of I2C
devices is here done via devicetree as subnodes of the master controller.
-Example:
+Example::
i2c1: i2c@400a0000 {
/* ... master properties skipped ... */
you can instantiate your I2C devices explicitly. This is done by filling
a struct i2c_board_info and calling i2c_new_device().
-Example (from the sfe4001 network driver):
+Example (from the sfe4001 network driver)::
-static struct i2c_board_info sfe4001_hwmon_info = {
+ static struct i2c_board_info sfe4001_hwmon_info = {
I2C_BOARD_INFO("max6647", 0x4e),
-};
+ };
-int sfe4001_init(struct efx_nic *efx)
-{
+ int sfe4001_init(struct efx_nic *efx)
+ {
(...)
efx->board_info.hwmon_client =
i2c_new_device(&efx->i2c_adap, &sfe4001_hwmon_info);
(...)
-}
+ }
The above code instantiates 1 I2C device on the I2C bus which is on the
network adapter in question.
changing its design without notice). In this case, you can call
i2c_new_probed_device() instead of i2c_new_device().
-Example (from the nxp OHCI driver):
+Example (from the nxp OHCI driver)::
-static const unsigned short normal_i2c[] = { 0x2c, 0x2d, I2C_CLIENT_END };
+ static const unsigned short normal_i2c[] = { 0x2c, 0x2d, I2C_CLIENT_END };
-static int usb_hcd_nxp_probe(struct platform_device *pdev)
-{
+ static int usb_hcd_nxp_probe(struct platform_device *pdev)
+ {
(...)
struct i2c_adapter *i2c_adap;
struct i2c_board_info i2c_info;
normal_i2c, NULL);
i2c_put_adapter(i2c_adap);
(...)
-}
+ }
The above code instantiates up to 1 I2C device on the I2C bus which is on
the OHCI adapter in question. It first tries at address 0x2c, if nothing
drivers are loaded, and if any is found, an I2C device will be
instantiated automatically. In order to prevent any misbehavior of this
mechanism, the following restrictions apply:
+
* The I2C device driver must implement the detect() method, which
identifies a supported device by reading from arbitrary registers.
* Only buses which are likely to have a supported device and agree to be
Those of you familiar with the i2c subsystem of 2.4 kernels and early 2.6
kernels will find out that this method 3 is essentially similar to what
was done there. Two significant differences are:
+
* Probing is only one way to instantiate I2C devices now, while it was the
only way back then. Where possible, methods 1 and 2 should be preferred.
Method 3 should only be used when there is no other way, as it can have
segment, the address is sufficient to uniquely identify the device to be
deleted.
-Example:
-# echo eeprom 0x50 > /sys/bus/i2c/devices/i2c-3/new_device
+Example::
+
+ # echo eeprom 0x50 > /sys/bus/i2c/devices/i2c-3/new_device
While this interface should only be used when in-kernel device declaration
can't be done, there is a variety of cases where it can be helpful:
+
* The I2C driver usually detects devices (method 3 above) but the bus
segment your device lives on doesn't have the proper class bit set and
thus detection doesn't trigger.
+==========================
Kernel driver i2c-mux-gpio
+==========================
Author: Peter Korsgaard <peter.korsgaard@barco.com>
i2c-mux-gpio is an i2c mux driver providing access to I2C bus segments
from a master I2C bus and a hardware MUX controlled through GPIO pins.
-E.G.:
+E.G.::
---------- ---------- Bus segment 1 - - - - -
| | SCL/SDA | |-------------- | |
to control it. See include/linux/platform_data/i2c-mux-gpio.h for details.
E.G. something like this for a MUX providing 4 bus segments
-controlled through 3 GPIO pins:
+controlled through 3 GPIO pins::
-#include <linux/platform_data/i2c-mux-gpio.h>
-#include <linux/platform_device.h>
+ #include <linux/platform_data/i2c-mux-gpio.h>
+ #include <linux/platform_device.h>
-static const unsigned myboard_gpiomux_gpios[] = {
+ static const unsigned myboard_gpiomux_gpios[] = {
AT91_PIN_PC26, AT91_PIN_PC25, AT91_PIN_PC24
-};
+ };
-static const unsigned myboard_gpiomux_values[] = {
+ static const unsigned myboard_gpiomux_values[] = {
0, 1, 2, 3
-};
+ };
-static struct i2c_mux_gpio_platform_data myboard_i2cmux_data = {
+ static struct i2c_mux_gpio_platform_data myboard_i2cmux_data = {
.parent = 1,
.base_nr = 2, /* optional */
.values = myboard_gpiomux_values,
.gpios = myboard_gpiomux_gpios,
.n_gpios = ARRAY_SIZE(myboard_gpiomux_gpios),
.idle = 4, /* optional */
-};
+ };
-static struct platform_device myboard_i2cmux = {
+ static struct platform_device myboard_i2cmux = {
.name = "i2c-mux-gpio",
.id = 0,
.dev = {
.platform_data = &myboard_i2cmux_data,
},
-};
+ };
If you don't know the absolute GPIO pin numbers at registration time,
you can instead provide a chip name (.chip_name) and relative GPIO pin
+=================================================
I2C device driver binding control from user-space
=================================================
Attaching a driver to an I2C device
-----------------------------------
-Old method (module parameters):
-# modprobe <driver> probe=1,0x2d
-# modprobe <driver> force=1,0x2d
-# modprobe <driver> force_<device>=1,0x2d
+Old method (module parameters)::
+
+ # modprobe <driver> probe=1,0x2d
+ # modprobe <driver> force=1,0x2d
+ # modprobe <driver> force_<device>=1,0x2d
+
+New method (sysfs interface)::
-New method (sysfs interface):
-# echo <device> 0x2d > /sys/bus/i2c/devices/i2c-1/new_device
+ # echo <device> 0x2d > /sys/bus/i2c/devices/i2c-1/new_device
Preventing a driver from attaching to an I2C device
---------------------------------------------------
-Old method (module parameters):
-# modprobe <driver> ignore=1,0x2f
+Old method (module parameters)::
+
+ # modprobe <driver> ignore=1,0x2f
+
+New method (sysfs interface)::
-New method (sysfs interface):
-# echo dummy 0x2f > /sys/bus/i2c/devices/i2c-1/new_device
-# modprobe <driver>
+ # echo dummy 0x2f > /sys/bus/i2c/devices/i2c-1/new_device
+ # modprobe <driver>
Of course, it is important to instantiate the "dummy" device before loading
the driver. The dummy device will be handled by i2c-core itself, preventing
+==============================
Linux I2C slave eeprom backend
==============================
This is a proof-of-concept backend which acts like an EEPROM on the connected
I2C bus. The memory contents can be modified from userspace via this file
-located in sysfs:
+located in sysfs::
/sys/bus/i2c/devices/<device-directory>/slave-eeprom
As of 2015, Linux doesn't support poll on binary sysfs files, so there is no
notification when another master changed the content.
-
+=====================================
Linux I2C slave interface description
=====================================
needed. The backend driver and the I2C bus driver communicate via events. Here
is a small graph visualizing the data flow and the means by which data is
transported. The dotted line marks only one example. The backend could also
-use a character device, be in-kernel only, or something completely different:
+use a character device, be in-kernel only, or something completely different::
e.g. sysfs I2C slave events I/O registers
is that i2c slave backends have their own address space. So, you have to add
0x1000 to the address you would originally request. An example for
instantiating the slave-eeprom driver from userspace at the 7 bit address 0x64
-on bus 1:
+on bus 1::
# echo slave-24c02 0x1064 > /sys/bus/i2c/devices/i2c-1/new_device
I2C slave events
----------------
-The bus driver sends an event to the backend using the following function:
+The bus driver sends an event to the backend using the following function::
ret = i2c_slave_event(client, event, &val)
* I2C_SLAVE_WRITE_REQUESTED (mandatory)
-'val': unused
-'ret': always 0
+ 'val': unused
+
+ 'ret': always 0
Another I2C master wants to write data to us. This event should be sent once
our own address and the write bit was detected. The data did not arrive yet, so
* I2C_SLAVE_READ_REQUESTED (mandatory)
-'val': backend returns first byte to be sent
-'ret': always 0
+ 'val': backend returns first byte to be sent
+
+ 'ret': always 0
Another I2C master wants to read data from us. This event should be sent once
our own address and the read bit was detected. After returning, the bus driver
* I2C_SLAVE_WRITE_RECEIVED (mandatory)
-'val': bus driver delivers received byte
-'ret': 0 if the byte should be acked, some errno if the byte should be nacked
+ 'val': bus driver delivers received byte
+
+ 'ret': 0 if the byte should be acked, some errno if the byte should be nacked
Another I2C master has sent a byte to us which needs to be set in 'val'. If 'ret'
is zero, the bus driver should ack this byte. If 'ret' is an errno, then the byte
* I2C_SLAVE_READ_PROCESSED (mandatory)
-'val': backend returns next byte to be sent
-'ret': always 0
+ 'val': backend returns next byte to be sent
+
+ 'ret': always 0
The bus driver requests the next byte to be sent to another I2C master in
'val'. Important: This does not mean that the previous byte has been acked, it
* I2C_SLAVE_STOP (mandatory)
-'val': unused
-'ret': always 0
+ 'val': unused
+
+ 'ret': always 0
A stop condition was received. This can happen anytime and the backend should
reset its state machine for I2C transfers to be able to receive new requests.
* A master can send STOP at any time. For partially transferred buffers, this
means additional code to handle this exception. Such code tends to be
error-prone.
-
+======================
SMBus Protocol Summary
======================
transaction function, a device driver should always check (just once) for
the corresponding functionality flag to ensure that the underlying I2C
adapter supports the transaction in question. See
-<file:Documentation/i2c/functionality> for the details.
+<file:Documentation/i2c/functionality.rst> for the details.
Key to symbols
==============
+=============== =============================================================
S (1 bit) : Start bit
P (1 bit) : Stop bit
Rd/Wr (1 bit) : Read/Write bit. Rd equals 1, Wr equals 0.
-A, NA (1 bit) : Accept and reverse accept bit.
-Addr (7 bits): I2C 7 bit address. Note that this can be expanded as usual to
+A, NA (1 bit) : Accept and reverse accept bit.
+Addr (7 bits): I2C 7 bit address. Note that this can be expanded as usual to
get a 10 bit I2C address.
Comm (8 bits): Command byte, a data byte which often selects a register on
the device.
for 16 bit data.
Count (8 bits): A data byte containing the length of a block operation.
-[..]: Data sent by I2C device, as opposed to data sent by the host adapter.
+[..]: Data sent by I2C device, as opposed to data sent by the host
+ adapter.
+=============== =============================================================
SMBus Quick Command
===================
-This sends a single bit to the device, at the place of the Rd/Wr bit.
+This sends a single bit to the device, at the place of the Rd/Wr bit::
-A Addr Rd/Wr [A] P
+ A Addr Rd/Wr [A] P
Functionality flag: I2C_FUNC_SMBUS_QUICK
This reads a single byte from a device, without specifying a device
register. Some devices are so simple that this interface is enough; for
others, it is a shorthand if you want to read the same register as in
-the previous SMBus command.
+the previous SMBus command::
-S Addr Rd [A] [Data] NA P
+ S Addr Rd [A] [Data] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_BYTE
This operation is the reverse of Receive Byte: it sends a single byte
to a device. See Receive Byte for more information.
-S Addr Wr [A] Data [A] P
+::
+
+ S Addr Wr [A] Data [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_BYTE
============================================
This reads a single byte from a device, from a designated register.
-The register is specified through the Comm byte.
+The register is specified through the Comm byte::
-S Addr Wr [A] Comm [A] S Addr Rd [A] [Data] NA P
+ S Addr Wr [A] Comm [A] S Addr Rd [A] [Data] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_BYTE_DATA
This operation is very like Read Byte; again, data is read from a
device, from a designated register that is specified through the Comm
-byte. But this time, the data is a complete word (16 bits).
+byte. But this time, the data is a complete word (16 bits)::
-S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
+ S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_WORD_DATA
register is specified through the Comm byte. This is the opposite of
the Read Byte operation.
-S Addr Wr [A] Comm [A] Data [A] P
+::
+
+ S Addr Wr [A] Comm [A] Data [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_BYTE_DATA
This is the opposite of the Read Word operation. 16 bits
of data is written to a device, to the designated register that is
-specified through the Comm byte.
+specified through the Comm byte.::
-S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A] P
+ S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_WORD_DATA
===================
This command selects a device register (through the Comm byte), sends
-16 bits of data to it, and reads 16 bits of data in return.
+16 bits of data to it, and reads 16 bits of data in return::
-S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A]
- S Addr Rd [A] [DataLow] A [DataHigh] NA P
+ S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A]
+ S Addr Rd [A] [DataLow] A [DataHigh] NA P
Functionality flag: I2C_FUNC_SMBUS_PROC_CALL
SMBus Block Read: i2c_smbus_read_block_data()
==============================================
-This command reads a block of up to 32 bytes from a device, from a
+This command reads a block of up to 32 bytes from a device, from a
designated register that is specified through the Comm byte. The amount
of data is specified by the device in the Count byte.
-S Addr Wr [A] Comm [A]
- S Addr Rd [A] [Count] A [Data] A [Data] A ... A [Data] NA P
+::
+
+ S Addr Wr [A] Comm [A]
+ S Addr Rd [A] [Count] A [Data] A [Data] A ... A [Data] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_BLOCK_DATA
SMBus Block Write: i2c_smbus_write_block_data()
================================================
-The opposite of the Block Read command, this writes up to 32 bytes to
+The opposite of the Block Read command, this writes up to 32 bytes to
a device, to a designated register that is specified through the
Comm byte. The amount of data is specified in the Count byte.
-S Addr Wr [A] Comm [A] Count [A] Data [A] Data [A] ... [A] Data [A] P
+::
+
+ S Addr Wr [A] Comm [A] Count [A] Data [A] Data [A] ... [A] Data [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_BLOCK_DATA
Revision 2.0 of the specification.
This command selects a device register (through the Comm byte), sends
-1 to 31 bytes of data to it, and reads 1 to 31 bytes of data in return.
+1 to 31 bytes of data to it, and reads 1 to 31 bytes of data in return::
-S Addr Wr [A] Comm [A] Count [A] Data [A] ...
- S Addr Rd [A] [Count] A [Data] ... A P
+ S Addr Wr [A] Comm [A] Count [A] Data [A] ...
+ S Addr Rd [A] [Count] A [Data] ... A P
Functionality flag: I2C_FUNC_SMBUS_BLOCK_PROC_CALL
It is the same form as Write Word, with the command code replaced by the
alerting device's address.
-[S] [HostAddr] [Wr] A [DevAddr] A [DataLow] A [DataHigh] A [P]
+::
+
+ [S] [HostAddr] [Wr] A [DevAddr] A [DataLow] A [DataHigh] A [P]
This is implemented in the following way in the Linux kernel:
+
* I2C bus drivers which support SMBus Host Notify should report
I2C_FUNC_SMBUS_HOST_NOTIFY.
* I2C bus drivers trigger SMBus Host Notify by a call to
to know which slave triggered the interrupt.
This is implemented the following way in the Linux kernel:
+
* I2C bus drivers which support SMBus alert should call
i2c_setup_smbus_alert() to setup SMBus alert support.
* I2C drivers for devices which can trigger SMBus alerts should implement
I2C Block Read: i2c_smbus_read_i2c_block_data()
================================================
-This command reads a block of bytes from a device, from a
-designated register that is specified through the Comm byte.
+This command reads a block of bytes from a device, from a
+designated register that is specified through the Comm byte::
-S Addr Wr [A] Comm [A]
- S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
+ S Addr Wr [A] Comm [A]
+ S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_I2C_BLOCK
I2C Block Write: i2c_smbus_write_i2c_block_data()
==================================================
-The opposite of the Block Read command, this writes bytes to
+The opposite of the Block Read command, this writes bytes to
a device, to a designated register that is specified through the
Comm byte. Note that command lengths of 0, 2, or more bytes are
supported as they are indistinguishable from data.
-S Addr Wr [A] Comm [A] Data [A] Data [A] ... [A] Data [A] P
+::
+
+ S Addr Wr [A] Comm [A] Data [A] Data [A] ... [A] Data [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_I2C_BLOCK
+=============
I2C and SMBus
=============
-I2C (pronounce: I squared C) is a protocol developed by Philips. It is a
+I2C (pronounce: I squared C) is a protocol developed by Philips. It is a
slow two-wire protocol (variable speed, up to 400 kHz), with a high speed
extension (3.4 MHz). It provides an inexpensive bus for connecting many
types of devices with infrequent or low bandwidth communications needs.
Terminology
===========
-When we talk about I2C, we use the following terms:
+When we talk about I2C, we use the following terms::
+
Bus -> Algorithm
Adapter
Device -> Driver
+=====================
+I2C Ten-bit Addresses
+=====================
+
The I2C protocol knows about two kinds of device addresses: normal 7 bit
addresses, and an extended set of 10 bit addresses. The sets of addresses
do not intersect: the 7 bit address 0x10 is not the same as the 10 bit
The current 10 bit address support is minimal. It should work, however
you can expect some problems along the way:
+
* Not all bus drivers support 10-bit addresses. Some don't because the
hardware doesn't support them (SMBus doesn't require 10-bit address
support for example), some don't because nobody bothered adding the
+=================================================
Upgrading I2C Drivers to the new 2.6 Driver Model
=================================================
Example old-style driver
------------------------
+::
-struct example_state {
+ struct example_state {
struct i2c_client client;
....
-};
+ };
-static struct i2c_driver example_driver;
+ static struct i2c_driver example_driver;
-static unsigned short ignore[] = { I2C_CLIENT_END };
-static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END };
+ static unsigned short ignore[] = { I2C_CLIENT_END };
+ static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END };
-I2C_CLIENT_INSMOD;
+ I2C_CLIENT_INSMOD;
-static int example_attach(struct i2c_adapter *adap, int addr, int kind)
-{
+ static int example_attach(struct i2c_adapter *adap, int addr, int kind)
+ {
struct example_state *state;
struct device *dev = &adap->dev; /* to use for dev_ reports */
int ret;
dev_info(dev, "example client created\n");
return 0;
-}
+ }
-static int example_detach(struct i2c_client *client)
-{
+ static int example_detach(struct i2c_client *client)
+ {
struct example_state *state = i2c_get_clientdata(client);
i2c_detach_client(client);
kfree(state);
return 0;
-}
+ }
-static int example_attach_adapter(struct i2c_adapter *adap)
-{
+ static int example_attach_adapter(struct i2c_adapter *adap)
+ {
return i2c_probe(adap, &addr_data, example_attach);
-}
+ }
-static struct i2c_driver example_driver = {
- .driver = {
+ static struct i2c_driver example_driver = {
+ .driver = {
.owner = THIS_MODULE,
.name = "example",
.pm = &example_pm_ops,
},
.attach_adapter = example_attach_adapter,
.detach_client = example_detach,
-};
+ };
Updating the client
devices and their associated address supplied by the code registering
the busses. This means that the driver .attach_adapter and
.detach_client methods can be removed, along with the addr_data,
-as follows:
+as follows::
-- static struct i2c_driver example_driver;
+ - static struct i2c_driver example_driver;
-- static unsigned short ignore[] = { I2C_CLIENT_END };
-- static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END };
+ - static unsigned short ignore[] = { I2C_CLIENT_END };
+ - static unsigned short normal_addr[] = { OUR_ADDR, I2C_CLIENT_END };
-- I2C_CLIENT_INSMOD;
+ - I2C_CLIENT_INSMOD;
-- static int example_attach_adapter(struct i2c_adapter *adap)
-- {
-- return i2c_probe(adap, &addr_data, example_attach);
-- }
+ - static int example_attach_adapter(struct i2c_adapter *adap)
+ - {
+ - return i2c_probe(adap, &addr_data, example_attach);
+ - }
- static struct i2c_driver example_driver = {
-- .attach_adapter = example_attach_adapter,
-- .detach_client = example_detach,
- }
+ static struct i2c_driver example_driver = {
+ - .attach_adapter = example_attach_adapter,
+ - .detach_client = example_detach,
+ }
-Add the probe and remove methods to the i2c_driver, as so:
+Add the probe and remove methods to the i2c_driver, as so::
- static struct i2c_driver example_driver = {
-+ .probe = example_probe,
-+ .remove = example_remove,
- }
+ static struct i2c_driver example_driver = {
+ + .probe = example_probe,
+ + .remove = example_remove,
+ }
Change the example_attach method to accept the new parameters
-which include the i2c_client that it will be working with:
+which include the i2c_client that it will be working with::
-- static int example_attach(struct i2c_adapter *adap, int addr, int kind)
-+ static int example_probe(struct i2c_client *client,
-+ const struct i2c_device_id *id)
+ - static int example_attach(struct i2c_adapter *adap, int addr, int kind)
+ + static int example_probe(struct i2c_client *client,
+ + const struct i2c_device_id *id)
Change the name of example_attach to example_probe to align it with the
i2c_driver entry names. The rest of the probe routine will now need to be
The necessary client fields have already been setup before
the probe function is called, so the following client setup
-can be removed:
+can be removed::
-- example->client.addr = addr;
-- example->client.flags = 0;
-- example->client.adapter = adap;
--
-- strscpy(client->i2c_client.name, "example", sizeof(client->i2c_client.name));
+ - example->client.addr = addr;
+ - example->client.flags = 0;
+ - example->client.adapter = adap;
+ -
+ - strscpy(client->i2c_client.name, "example", sizeof(client->i2c_client.name));
-The i2c_set_clientdata is now:
+The i2c_set_clientdata is now::
-- i2c_set_clientdata(&state->client, state);
-+ i2c_set_clientdata(client, state);
+ - i2c_set_clientdata(&state->client, state);
+ + i2c_set_clientdata(client, state);
The call to i2c_attach_client is no longer needed, if the probe
routine exits successfully, then the driver will be automatically
-attached by the core. Change the probe routine as so:
+attached by the core. Change the probe routine as so::
-- ret = i2c_attach_client(&state->i2c_client);
-- if (ret < 0) {
-- dev_err(dev, "failed to attach client\n");
-- kfree(state);
-- return ret;
-- }
+ - ret = i2c_attach_client(&state->i2c_client);
+ - if (ret < 0) {
+ - dev_err(dev, "failed to attach client\n");
+ - kfree(state);
+ - return ret;
+ - }
Remove the storage of 'struct i2c_client' from the 'struct example_state'
as we are provided with the i2c_client in our example_probe. Instead we
store a pointer to it for when it is needed.
-struct example_state {
-- struct i2c_client client;
-+ struct i2c_client *client;
+::
+
+ struct example_state {
+ - struct i2c_client client;
+ + struct i2c_client *client;
-the new i2c client as so:
+the new i2c client as so::
-- struct device *dev = &adap->dev; /* to use for dev_ reports */
-+ struct device *dev = &i2c_client->dev; /* to use for dev_ reports */
+ - struct device *dev = &adap->dev; /* to use for dev_ reports */
+ + struct device *dev = &i2c_client->dev; /* to use for dev_ reports */
And remove the change after our client is attached, as the driver no
-longer needs to register a new client structure with the core:
+longer needs to register a new client structure with the core::
-- dev = &state->i2c_client.dev;
+ - dev = &state->i2c_client.dev;
In the probe routine, ensure that the new state has the client stored
-in it:
+in it::
-static int example_probe(struct i2c_client *i2c_client,
+ static int example_probe(struct i2c_client *i2c_client,
const struct i2c_device_id *id)
-{
+ {
struct example_state *state;
- struct device *dev = &i2c_client->dev;
+ struct device *dev = &i2c_client->dev;
int ret;
state = kzalloc(sizeof(struct example_state), GFP_KERNEL);
return -ENOMEM;
}
-+ state->client = i2c_client;
+ + state->client = i2c_client;
Update the detach method, by changing the name to _remove and
to delete the i2c_detach_client call. It is possible that you
can also remove the ret variable as it is not needed for any
of the core functions.
-- static int example_detach(struct i2c_client *client)
-+ static int example_remove(struct i2c_client *client)
-{
+::
+
+ - static int example_detach(struct i2c_client *client)
+ + static int example_remove(struct i2c_client *client)
+ {
struct example_state *state = i2c_get_clientdata(client);
-- i2c_detach_client(client);
+ - i2c_detach_client(client);
And finally ensure that we have the correct ID table for the i2c-core
-and other utilities:
+and other utilities::
-+ struct i2c_device_id example_idtable[] = {
-+ { "example", 0 },
-+ { }
-+};
-+
-+MODULE_DEVICE_TABLE(i2c, example_idtable);
+ + struct i2c_device_id example_idtable[] = {
+ + { "example", 0 },
+ + { }
+ +};
+ +
+ +MODULE_DEVICE_TABLE(i2c, example_idtable);
-static struct i2c_driver example_driver = {
- .driver = {
+ static struct i2c_driver example_driver = {
+ .driver = {
.owner = THIS_MODULE,
.name = "example",
},
-+ .id_table = example_ids,
+ + .id_table = example_ids,
-Our driver should now look like this:
+Our driver should now look like this::
-struct example_state {
+ struct example_state {
struct i2c_client *client;
....
-};
+ };
-static int example_probe(struct i2c_client *client,
- const struct i2c_device_id *id)
-{
+ static int example_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+ {
struct example_state *state;
struct device *dev = &client->dev;
dev_info(dev, "example client created\n");
return 0;
-}
+ }
-static int example_remove(struct i2c_client *client)
-{
+ static int example_remove(struct i2c_client *client)
+ {
struct example_state *state = i2c_get_clientdata(client);
kfree(state);
return 0;
-}
+ }
-static struct i2c_device_id example_idtable[] = {
+ static struct i2c_device_id example_idtable[] = {
{ "example", 0 },
{ }
-};
+ };
-MODULE_DEVICE_TABLE(i2c, example_idtable);
+ MODULE_DEVICE_TABLE(i2c, example_idtable);
-static struct i2c_driver example_driver = {
- .driver = {
+ static struct i2c_driver example_driver = {
+ .driver = {
.owner = THIS_MODULE,
.name = "example",
.pm = &example_pm_ops,
.id_table = example_idtable,
.probe = example_probe,
.remove = example_remove,
-};
+ };
+===================
+Writing I2C Clients
+===================
+
This is a small guide for those who want to write kernel drivers for I2C
or SMBus devices, using Linux as the protocol host/master (not slave).
Try to keep the kernel namespace as clean as possible. The best way to
do this is to use a unique prefix for all global symbols. This is
especially important for exported symbols, but it is a good idea to do
-it for non-exported symbols too. We will use the prefix `foo_' in this
+it for non-exported symbols too. We will use the prefix ``foo_`` in this
tutorial.
provide. A client structure holds device-specific information like the
driver model device node, and its I2C address.
-static struct i2c_device_id foo_idtable[] = {
+::
+
+ static struct i2c_device_id foo_idtable[] = {
{ "foo", my_id_for_foo },
{ "bar", my_id_for_bar },
{ }
-};
+ };
-MODULE_DEVICE_TABLE(i2c, foo_idtable);
+ MODULE_DEVICE_TABLE(i2c, foo_idtable);
-static struct i2c_driver foo_driver = {
+ static struct i2c_driver foo_driver = {
.driver = {
.name = "foo",
.pm = &foo_pm_ops, /* optional */
.shutdown = foo_shutdown, /* optional */
.command = foo_command, /* optional, deprecated */
-}
+ }
The name field is the driver name, and must not contain spaces. It
should match the module name (if the driver can be compiled as a module),
Extra client data
=================
-Each client structure has a special `data' field that can point to any
+Each client structure has a special ``data`` field that can point to any
structure at all. You should use this to keep device-specific data.
+::
+
/* store the value */
void i2c_set_clientdata(struct i2c_client *client, void *data);
/* retrieve the value */
void *i2c_get_clientdata(const struct i2c_client *client);
-Note that starting with kernel 2.6.34, you don't have to set the `data' field
+Note that starting with kernel 2.6.34, you don't have to set the ``data`` field
to NULL in remove() or if probe() failed anymore. The i2c-core does this
automatically on these occasions. Those are also the only times the core will
touch this field.
be encapsulated.
The below functions are simple examples, and should not be copied
-literally.
+literally::
-int foo_read_value(struct i2c_client *client, u8 reg)
-{
+ int foo_read_value(struct i2c_client *client, u8 reg)
+ {
if (reg < 0x10) /* byte-sized register */
return i2c_smbus_read_byte_data(client, reg);
else /* word-sized register */
return i2c_smbus_read_word_data(client, reg);
-}
+ }
-int foo_write_value(struct i2c_client *client, u8 reg, u16 value)
-{
+ int foo_write_value(struct i2c_client *client, u8 reg, u16 value)
+ {
if (reg == 0x10) /* Impossible to write - driver error! */
return -EINVAL;
else if (reg < 0x10) /* byte-sized register */
return i2c_smbus_write_byte_data(client, reg, value);
else /* word-sized register */
return i2c_smbus_write_word_data(client, reg, value);
-}
+ }
Probing and attaching
kind of driver in Linux: they provide a probe() method to bind to
those devices, and a remove() method to unbind.
+::
+
static int foo_probe(struct i2c_client *client,
const struct i2c_device_id *id);
static int foo_remove(struct i2c_client *client);
you have to do some initializing. Fortunately, just registering the
driver module is usually enough.
-static int __init foo_init(void)
-{
+::
+
+ static int __init foo_init(void)
+ {
return i2c_add_driver(&foo_driver);
-}
-module_init(foo_init);
+ }
+ module_init(foo_init);
-static void __exit foo_cleanup(void)
-{
+ static void __exit foo_cleanup(void)
+ {
i2c_del_driver(&foo_driver);
-}
-module_exit(foo_cleanup);
+ }
+ module_exit(foo_cleanup);
-The module_i2c_driver() macro can be used to reduce above code.
+ The module_i2c_driver() macro can be used to reduce above code.
-module_i2c_driver(foo_driver);
+ module_i2c_driver(foo_driver);
-Note that some functions are marked by `__init'. These functions can
+Note that some functions are marked by ``__init``. These functions can
be removed after kernel booting (or module loading) is completed.
-Likewise, functions marked by `__exit' are dropped by the compiler when
+Likewise, functions marked by ``__exit`` are dropped by the compiler when
the code is built into the kernel, as they would never be called.
Driver Information
==================
-/* Substitute your own name and email address */
-MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>"
-MODULE_DESCRIPTION("Driver for Barf Inc. Foo I2C devices");
+::
-/* a few non-GPL license types are also allowed */
-MODULE_LICENSE("GPL");
+ /* Substitute your own name and email address */
+ MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>"
+ MODULE_DESCRIPTION("Driver for Barf Inc. Foo I2C devices");
+
+ /* a few non-GPL license types are also allowed */
+ MODULE_LICENSE("GPL");
Power Management
Plain I2C communication
-----------------------
+::
+
int i2c_master_send(struct i2c_client *client, const char *buf,
int count);
int i2c_master_recv(struct i2c_client *client, char *buf, int count);
less than 64k since msg.len is u16.) Returned is the actual number of bytes
read/written.
+::
+
int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msg,
int num);
for each message the client address, the number of bytes of the message
and the message data itself.
-You can read the file `i2c-protocol' for more information about the
+You can read the file ``i2c-protocol`` for more information about the
actual I2C protocol.
SMBus communication
-------------------
+::
+
s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
unsigned short flags, char read_write, u8 command,
int size, union i2c_smbus_data *data);
This is the generic SMBus function. All functions below are implemented
in terms of it. Never use this function directly!
+::
+
s32 i2c_smbus_read_byte(struct i2c_client *client);
s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value);
s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command);
const u8 *values);
These ones were removed from i2c-core because they had no users, but could
-be added back later if needed:
+be added back later if needed::
s32 i2c_smbus_write_quick(struct i2c_client *client, u8 value);
s32 i2c_smbus_process_call(struct i2c_client *client,
value, except for block transactions, which return the number of values
read. The block buffers need not be longer than 32 bytes.
-You can read the file `smbus-protocol' for more information about the
+You can read the file ``smbus-protocol`` for more information about the
actual SMBus protocol.
========================
Below all general purpose routines are listed, that were not mentioned
-before.
+before::
/* Return the adapter number for a specific adapter */
int i2c_adapter_id(struct i2c_adapter *adap);
fb/index
fpga/index
hid/index
+ i2c/index
iio/index
infiniband/index
leds/index
The driver does not probe for supported chips, since the SI18IS602/603 does not
support Chip ID registers. You will have to instantiate the devices explicitly.
-Please see Documentation/i2c/instantiating-devices for details.
+Please see Documentation/i2c/instantiating-devices.rst for details.
Usage Notes
M: Rudolf Marek <r.marek@assembler.cz>
L: linux-i2c@vger.kernel.org
S: Maintained
-F: Documentation/i2c/busses/i2c-ali1563
+F: Documentation/i2c/busses/i2c-ali1563.rst
F: drivers/i2c/busses/i2c-ali1563.c
ALLEGRO DVT VIDEO IP CORE DRIVER
S: Supported
F: drivers/i2c/muxes/i2c-mux-gpio.c
F: include/linux/platform_data/i2c-mux-gpio.h
-F: Documentation/i2c/muxes/i2c-mux-gpio
+F: Documentation/i2c/muxes/i2c-mux-gpio.rst
GENERIC HDLC (WAN) DRIVERS
M: Krzysztof Halasa <khc@pm.waw.pl>
M: Ajay Gupta <ajayg@nvidia.com>
L: linux-i2c@vger.kernel.org
S: Maintained
-F: Documentation/i2c/busses/i2c-nvidia-gpu
+F: Documentation/i2c/busses/i2c-nvidia-gpu.rst
F: drivers/i2c/busses/i2c-nvidia-gpu.c
I2C MUXES
M: Peter Rosin <peda@axentia.se>
L: linux-i2c@vger.kernel.org
S: Maintained
-F: Documentation/i2c/i2c-topology
+F: Documentation/i2c/i2c-topology.rst
F: Documentation/i2c/muxes/
F: Documentation/devicetree/bindings/i2c/i2c-mux*
F: Documentation/devicetree/bindings/i2c/i2c-arb*
M: Jean Delvare <jdelvare@suse.com>
L: linux-i2c@vger.kernel.org
S: Maintained
-F: Documentation/i2c/busses/i2c-parport
-F: Documentation/i2c/busses/i2c-parport-light
+F: Documentation/i2c/busses/i2c-parport.rst
+F: Documentation/i2c/busses/i2c-parport-light.rst
F: drivers/i2c/busses/i2c-parport.c
F: drivers/i2c/busses/i2c-parport-light.c
M: Jean Delvare <jdelvare@suse.com>
L: linux-i2c@vger.kernel.org
S: Maintained
-F: Documentation/i2c/busses/i2c-taos-evm
+F: Documentation/i2c/busses/i2c-taos-evm.rst
F: drivers/i2c/busses/i2c-taos-evm.c
I2C-TINY-USB DRIVER
M: Jean Delvare <jdelvare@suse.com>
L: linux-i2c@vger.kernel.org
S: Maintained
-F: Documentation/i2c/busses/i2c-ali1535
-F: Documentation/i2c/busses/i2c-ali1563
-F: Documentation/i2c/busses/i2c-ali15x3
-F: Documentation/i2c/busses/i2c-amd756
-F: Documentation/i2c/busses/i2c-amd8111
-F: Documentation/i2c/busses/i2c-i801
-F: Documentation/i2c/busses/i2c-nforce2
-F: Documentation/i2c/busses/i2c-piix4
-F: Documentation/i2c/busses/i2c-sis5595
-F: Documentation/i2c/busses/i2c-sis630
-F: Documentation/i2c/busses/i2c-sis96x
-F: Documentation/i2c/busses/i2c-via
-F: Documentation/i2c/busses/i2c-viapro
+F: Documentation/i2c/busses/i2c-ali1535.rst
+F: Documentation/i2c/busses/i2c-ali1563.rst
+F: Documentation/i2c/busses/i2c-ali15x3.rst
+F: Documentation/i2c/busses/i2c-amd756.rst
+F: Documentation/i2c/busses/i2c-amd8111.rst
+F: Documentation/i2c/busses/i2c-i801.rst
+F: Documentation/i2c/busses/i2c-nforce2.rst
+F: Documentation/i2c/busses/i2c-piix4.rst
+F: Documentation/i2c/busses/i2c-sis5595.rst
+F: Documentation/i2c/busses/i2c-sis630.rst
+F: Documentation/i2c/busses/i2c-sis96x.rst
+F: Documentation/i2c/busses/i2c-via.rst
+F: Documentation/i2c/busses/i2c-viapro.rst
F: drivers/i2c/busses/i2c-ali1535.c
F: drivers/i2c/busses/i2c-ali1563.c
F: drivers/i2c/busses/i2c-ali15x3.c
M: Neil Horman <nhorman@tuxdriver.com>
L: linux-i2c@vger.kernel.org
F: drivers/i2c/busses/i2c-ismt.c
-F: Documentation/i2c/busses/i2c-ismt
+F: Documentation/i2c/busses/i2c-ismt.rst
I2C/SMBUS STUB DRIVER
M: Jean Delvare <jdelvare@suse.com>
S: Supported
F: drivers/i2c/busses/i2c-mlxcpld.c
F: drivers/i2c/muxes/i2c-mux-mlxcpld.c
-F: Documentation/i2c/busses/i2c-mlxcpld
+F: Documentation/i2c/busses/i2c-mlxcpld.rst
MELLANOX MLXCPLD LED DRIVER
M: Vadim Pasternak <vadimp@mellanox.com>
L: linux-i2c@vger.kernel.org
S: Maintained
F: Documentation/devicetree/bindings/i2c/i2c-ocores.txt
-F: Documentation/i2c/busses/i2c-ocores
+F: Documentation/i2c/busses/i2c-ocores.rst
F: drivers/i2c/busses/i2c-ocores.c
F: include/linux/platform_data/i2c-ocores.h
SCx200 CPU SUPPORT
M: Jim Cromie <jim.cromie@gmail.com>
S: Odd Fixes
-F: Documentation/i2c/busses/scx200_acb
+F: Documentation/i2c/busses/scx200_acb.rst
F: arch/x86/platform/scx200/
F: drivers/watchdog/scx200_wdt.c
F: drivers/i2c/busses/scx200*
*
* The ATXP1 can reside on I2C addresses 0x37 or 0x4e. The chip is
* not auto-detected by the driver and must be instantiated explicitly.
- * See Documentation/i2c/instantiating-devices for more information.
+ * See Documentation/i2c/instantiating-devices.rst for more information.
*/
#include <linux/kernel.h>
if (rv != -ENXIO) {
/*
* We expect ENXIO to reflect NACK
- * (per Documentation/i2c/fault-codes).
+ * (per Documentation/i2c/fault-codes.rst).
* Everything else is an error.
*/
dev_dbg(&client->dev,
Say Y here to use i2c-* device files, usually found in the /dev
directory on your system. They make it possible to have user-space
programs use the I2C bus. Information on how to do this is
- contained in the file <file:Documentation/i2c/dev-interface>.
+ contained in the file <file:Documentation/i2c/dev-interface.rst>.
This support is also available as a module. If so, the module
will be called i2c-dev.
especially for certain kinds of sensor chips.
If you do build this module, be sure to read the notes and warnings
- in <file:Documentation/i2c/i2c-stub>.
+ in <file:Documentation/i2c/i2c-stub.rst>.
If you don't know what to do here, definitely say N.
and makes it easier to add support for new devices.
An adapter type parameter is now mandatory. Please read the file
- Documentation/i2c/busses/i2c-parport for details.
+ Documentation/i2c/busses/i2c-parport.rst for details.
Another driver exists, named i2c-parport-light, which doesn't depend
on the parport driver. This is meant for embedded systems. Don't say
* SMBus Host Notify yes
* Interrupt processing yes
*
- * See the file Documentation/i2c/busses/i2c-i801 for details.
+ * See the file Documentation/i2c/busses/i2c-i801.rst for details.
*/
#include <linux/interrupt.h>
/*
* Voluntarily dropping error code of kstrtou8 since all
* error code that it could return are invalid according
- * to Documentation/i2c/fault-codes.
+ * to Documentation/i2c/fault-codes.rst.
*/
if (kstrtou8(p + 1, 16, &data->byte))
return -EPROTO;
dev_warn(&adapter->dev,
"This adapter will soon drop class based instantiation of devices. "
"Please make sure client 0x%02x gets instantiated by other means. "
- "Check 'Documentation/i2c/instantiating-devices' for details.\n",
+ "Check 'Documentation/i2c/instantiating-devices.rst' for details.\n",
info.addr);
dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
if (adapter->class == I2C_CLASS_DEPRECATED) {
dev_dbg(&adapter->dev,
"This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. "
- "If you need it, check 'Documentation/i2c/instantiating-devices' for alternatives.\n",
+ "If you need it, check 'Documentation/i2c/instantiating-devices.rst' for alternatives.\n",
driver->driver.name);
return 0;
}
* Varies depending on bus type of the device. As there is no device
* here, call probe directly. For information on device registration
* i2c:
- * Documentation/i2c/writing-clients
+ * Documentation/i2c/writing-clients.rst
* spi:
* Documentation/spi/spi-summary
*/
*/
/*
* It would be more efficient to use i2c msgs/i2c_transfer directly but, as
- * recommened in .../Documentation/i2c/writing-clients section
+ * recommended in .../Documentation/i2c/writing-clients.rst section
* "Sending and receiving", using SMBus level communication is preferred.
*/
*
* The return codes from the @master_xfer{_atomic} fields should indicate the
* type of error code that occurred during the transfer, as documented in the
- * Kernel Documentation file Documentation/i2c/fault-codes.
+ * Kernel Documentation file Documentation/i2c/fault-codes.rst.
*/
struct i2c_algorithm {
/*
projects / platform / kernel / linux-starfive.git / commitdiff