3 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
5 * SPDX-License-Identifier: GPL-2.0+
11 /* Controller-specific definitions: */
14 #define SPI_CPHA 0x01 /* clock phase */
15 #define SPI_CPOL 0x02 /* clock polarity */
16 #define SPI_MODE_0 (0|0) /* (original MicroWire) */
17 #define SPI_MODE_1 (0|SPI_CPHA)
18 #define SPI_MODE_2 (SPI_CPOL|0)
19 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
20 #define SPI_CS_HIGH 0x04 /* CS active high */
21 #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
22 #define SPI_3WIRE 0x10 /* SI/SO signals shared */
23 #define SPI_LOOP 0x20 /* loopback mode */
24 #define SPI_SLAVE 0x40 /* slave mode */
25 #define SPI_PREAMBLE 0x80 /* Skip preamble bytes */
27 /* SPI transfer flags */
28 #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */
29 #define SPI_XFER_END 0x02 /* Deassert CS after transfer */
31 /* Header byte that marks the start of the message */
32 #define SPI_PREAMBLE_END_BYTE 0xec
35 * struct spi_slave: Representation of a SPI slave,
36 * i.e. what we're communicating with.
38 * Drivers are expected to extend this with controller-specific data.
40 * bus: ID of the bus that the slave is attached to.
41 * cs: ID of the chip select connected to the slave.
42 * max_write_size: If non-zero, the maximum number of bytes which can
43 * be written at once, excluding command bytes.
48 unsigned int max_write_size;
52 * Initialization, must be called once on start up.
54 * TODO: I don't think we really need this.
59 * spi_do_alloc_slave - Allocate a new SPI slave (internal)
61 * Allocate and zero all fields in the spi slave, and set the bus/chip
62 * select. Use the helper macro spi_alloc_slave() to call this.
64 * @offset: Offset of struct spi_slave within slave structure.
65 * @size: Size of slave structure.
66 * @bus: Bus ID of the slave chip.
67 * @cs: Chip select ID of the slave chip on the specified bus.
69 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
73 * spi_alloc_slave - Allocate a new SPI slave
75 * Allocate and zero all fields in the spi slave, and set the bus/chip
78 * @_struct: Name of structure to allocate (e.g. struct tegra_spi).
79 * This structure must contain a member 'struct spi_slave *slave'.
80 * @bus: Bus ID of the slave chip.
81 * @cs: Chip select ID of the slave chip on the specified bus.
83 #define spi_alloc_slave(_struct, bus, cs) \
84 spi_do_alloc_slave(offsetof(_struct, slave), \
85 sizeof(_struct), bus, cs)
88 * spi_alloc_slave_base - Allocate a new SPI slave with no private data
90 * Allocate and zero all fields in the spi slave, and set the bus/chip
93 * @bus: Bus ID of the slave chip.
94 * @cs: Chip select ID of the slave chip on the specified bus.
96 #define spi_alloc_slave_base(bus, cs) \
97 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
100 * Set up communications parameters for a SPI slave.
102 * This must be called once for each slave. Note that this function
103 * usually doesn't touch any actual hardware, it only initializes the
104 * contents of spi_slave so that the hardware can be easily
107 * @bus: Bus ID of the slave chip.
108 * @cs: Chip select ID of the slave chip on the specified bus.
109 * @max_hz: Maximum SCK rate in Hz.
110 * @mode: Clock polarity, clock phase and other parameters.
112 * Returns: A spi_slave reference that can be used in subsequent SPI
113 * calls, or NULL if one or more of the parameters are not supported.
115 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
116 unsigned int max_hz, unsigned int mode);
119 * Free any memory associated with a SPI slave.
121 * @slave: The SPI slave
123 void spi_free_slave(struct spi_slave *slave);
126 * Claim the bus and prepare it for communication with a given slave.
128 * This must be called before doing any transfers with a SPI slave. It
129 * will enable and initialize any SPI hardware as necessary, and make
130 * sure that the SCK line is in the correct idle state. It is not
131 * allowed to claim the same bus for several slaves without releasing
132 * the bus in between.
134 * @slave: The SPI slave
136 * Returns: 0 if the bus was claimed successfully, or a negative value
139 int spi_claim_bus(struct spi_slave *slave);
142 * Release the SPI bus
144 * This must be called once for every call to spi_claim_bus() after
145 * all transfers have finished. It may disable any SPI hardware as
148 * @slave: The SPI slave
150 void spi_release_bus(struct spi_slave *slave);
155 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
156 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
158 * The source of the outgoing bits is the "dout" parameter and the
159 * destination of the input bits is the "din" parameter. Note that "dout"
160 * and "din" can point to the same memory location, in which case the
161 * input data overwrites the output data (since both are buffered by
162 * temporary variables, this is OK).
164 * spi_xfer() interface:
165 * @slave: The SPI slave which will be sending/receiving the data.
166 * @bitlen: How many bits to write and read.
167 * @dout: Pointer to a string of bits to send out. The bits are
168 * held in a byte array and are sent MSB first.
169 * @din: Pointer to a string of bits that will be filled in.
170 * @flags: A bitwise combination of SPI_XFER_* flags.
172 * Returns: 0 on success, not 0 on failure
174 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
175 void *din, unsigned long flags);
178 * Determine if a SPI chipselect is valid.
179 * This function is provided by the board if the low-level SPI driver
180 * needs it to determine if a given chipselect is actually valid.
182 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
185 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
188 * Activate a SPI chipselect.
189 * This function is provided by the board code when using a driver
190 * that can't control its chipselects automatically (e.g.
191 * common/soft_spi.c). When called, it should activate the chip select
192 * to the device identified by "slave".
194 void spi_cs_activate(struct spi_slave *slave);
197 * Deactivate a SPI chipselect.
198 * This function is provided by the board code when using a driver
199 * that can't control its chipselects automatically (e.g.
200 * common/soft_spi.c). When called, it should deactivate the chip
201 * select to the device identified by "slave".
203 void spi_cs_deactivate(struct spi_slave *slave);
206 * Set transfer speed.
207 * This sets a new speed to be applied for next spi_xfer().
208 * @slave: The SPI slave
209 * @hz: The transfer speed
211 void spi_set_speed(struct spi_slave *slave, uint hz);
214 * Write 8 bits, then read 8 bits.
215 * @slave: The SPI slave we're communicating with
216 * @byte: Byte to be written
218 * Returns: The value that was read, or a negative value on error.
220 * TODO: This function probably shouldn't be inlined.
222 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
224 unsigned char dout[2];
225 unsigned char din[2];
231 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
232 return ret < 0 ? ret : din[1];
236 * Set up a SPI slave for a particular device tree node
238 * This calls spi_setup_slave() with the correct bus number. Call
239 * spi_free_slave() to free it later.
241 * @param blob Device tree blob
242 * @param node SPI peripheral node to use
243 * @param cs Chip select to use
244 * @param max_hz Maximum SCK rate in Hz (0 for default)
245 * @param mode Clock polarity, clock phase and other parameters
246 * @return pointer to new spi_slave structure
248 struct spi_slave *spi_setup_slave_fdt(const void *blob, int node,
249 unsigned int cs, unsigned int max_hz, unsigned int mode);