3 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
5 * See file CREDITS for list of people who contributed to this
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
27 /* Controller-specific definitions: */
30 #define SPI_CPHA 0x01 /* clock phase */
31 #define SPI_CPOL 0x02 /* clock polarity */
32 #define SPI_MODE_0 (0|0) /* (original MicroWire) */
33 #define SPI_MODE_1 (0|SPI_CPHA)
34 #define SPI_MODE_2 (SPI_CPOL|0)
35 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
36 #define SPI_CS_HIGH 0x04 /* CS active high */
37 #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
38 #define SPI_3WIRE 0x10 /* SI/SO signals shared */
39 #define SPI_LOOP 0x20 /* loopback mode */
41 /* SPI transfer flags */
42 #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */
43 #define SPI_XFER_END 0x02 /* Deassert CS after transfer */
45 /*-----------------------------------------------------------------------
46 * Representation of a SPI slave, i.e. what we're communicating with.
48 * Drivers are expected to extend this with controller-specific data.
50 * bus: ID of the bus that the slave is attached to.
51 * cs: ID of the chip select connected to the slave.
58 /*-----------------------------------------------------------------------
59 * Initialization, must be called once on start up.
61 * TODO: I don't think we really need this.
66 * spi_do_alloc_slave - Allocate a new SPI slave (internal)
68 * Allocate and zero all fields in the spi slave, and set the bus/chip
69 * select. Use the helper macro spi_alloc_slave() to call this.
71 * @offset: Offset of struct spi_slave within slave structure
72 * @size: Size of slave structure
73 * @bus: Bus ID of the slave chip.
74 * @cs: Chip select ID of the slave chip on the specified bus.
76 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
80 * spi_alloc_slave - Allocate a new SPI slave
82 * Allocate and zero all fields in the spi slave, and set the bus/chip
85 * @_struct: Name of structure to allocate (e.g. struct tegra_spi). This
86 * structure must contain a member 'struct spi_slave *slave'.
87 * @bus: Bus ID of the slave chip.
88 * @cs: Chip select ID of the slave chip on the specified bus.
90 #define spi_alloc_slave(_struct, bus, cs) \
91 spi_do_alloc_slave(offsetof(_struct, slave), \
92 sizeof(_struct), bus, cs)
95 * spi_alloc_slave_base - Allocate a new SPI slave with no private data
97 * Allocate and zero all fields in the spi slave, and set the bus/chip
100 * @bus: Bus ID of the slave chip.
101 * @cs: Chip select ID of the slave chip on the specified bus.
103 #define spi_alloc_slave_base(bus, cs) \
104 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
106 /*-----------------------------------------------------------------------
107 * Set up communications parameters for a SPI slave.
109 * This must be called once for each slave. Note that this function
110 * usually doesn't touch any actual hardware, it only initializes the
111 * contents of spi_slave so that the hardware can be easily
114 * bus: Bus ID of the slave chip.
115 * cs: Chip select ID of the slave chip on the specified bus.
116 * max_hz: Maximum SCK rate in Hz.
117 * mode: Clock polarity, clock phase and other parameters.
119 * Returns: A spi_slave reference that can be used in subsequent SPI
120 * calls, or NULL if one or more of the parameters are not supported.
122 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
123 unsigned int max_hz, unsigned int mode);
125 /*-----------------------------------------------------------------------
126 * Free any memory associated with a SPI slave.
128 * slave: The SPI slave
130 void spi_free_slave(struct spi_slave *slave);
132 /*-----------------------------------------------------------------------
133 * Claim the bus and prepare it for communication with a given slave.
135 * This must be called before doing any transfers with a SPI slave. It
136 * will enable and initialize any SPI hardware as necessary, and make
137 * sure that the SCK line is in the correct idle state. It is not
138 * allowed to claim the same bus for several slaves without releasing
139 * the bus in between.
141 * slave: The SPI slave
143 * Returns: 0 if the bus was claimed successfully, or a negative value
146 int spi_claim_bus(struct spi_slave *slave);
148 /*-----------------------------------------------------------------------
149 * Release the SPI bus
151 * This must be called once for every call to spi_claim_bus() after
152 * all transfers have finished. It may disable any SPI hardware as
155 * slave: The SPI slave
157 void spi_release_bus(struct spi_slave *slave);
159 /*-----------------------------------------------------------------------
162 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
163 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
165 * The source of the outgoing bits is the "dout" parameter and the
166 * destination of the input bits is the "din" parameter. Note that "dout"
167 * and "din" can point to the same memory location, in which case the
168 * input data overwrites the output data (since both are buffered by
169 * temporary variables, this is OK).
171 * spi_xfer() interface:
172 * slave: The SPI slave which will be sending/receiving the data.
173 * bitlen: How many bits to write and read.
174 * dout: Pointer to a string of bits to send out. The bits are
175 * held in a byte array and are sent MSB first.
176 * din: Pointer to a string of bits that will be filled in.
177 * flags: A bitwise combination of SPI_XFER_* flags.
179 * Returns: 0 on success, not 0 on failure
181 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
182 void *din, unsigned long flags);
184 /*-----------------------------------------------------------------------
185 * Determine if a SPI chipselect is valid.
186 * This function is provided by the board if the low-level SPI driver
187 * needs it to determine if a given chipselect is actually valid.
189 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
192 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
194 /*-----------------------------------------------------------------------
195 * Activate a SPI chipselect.
196 * This function is provided by the board code when using a driver
197 * that can't control its chipselects automatically (e.g.
198 * common/soft_spi.c). When called, it should activate the chip select
199 * to the device identified by "slave".
201 void spi_cs_activate(struct spi_slave *slave);
203 /*-----------------------------------------------------------------------
204 * Deactivate a SPI chipselect.
205 * This function is provided by the board code when using a driver
206 * that can't control its chipselects automatically (e.g.
207 * common/soft_spi.c). When called, it should deactivate the chip
208 * select to the device identified by "slave".
210 void spi_cs_deactivate(struct spi_slave *slave);
212 /*-----------------------------------------------------------------------
213 * Set transfer speed.
214 * This sets a new speed to be applied for next spi_xfer().
215 * slave: The SPI slave
216 * hz: The transfer speed
218 void spi_set_speed(struct spi_slave *slave, uint hz);
220 /*-----------------------------------------------------------------------
221 * Write 8 bits, then read 8 bits.
222 * slave: The SPI slave we're communicating with
223 * byte: Byte to be written
225 * Returns: The value that was read, or a negative value on error.
227 * TODO: This function probably shouldn't be inlined.
229 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
231 unsigned char dout[2];
232 unsigned char din[2];
238 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
239 return ret < 0 ? ret : din[1];