2 * Common SPI Interface: Controller-specific definitions
5 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
7 * SPDX-License-Identifier: GPL-2.0+
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 */
30 #define SPI_XFER_MMAP 0x08 /* Memory Mapped start */
31 #define SPI_XFER_MMAP_END 0x10 /* Memory Mapped End */
33 /* Header byte that marks the start of the message */
34 #define SPI_PREAMBLE_END_BYTE 0xec
36 #define SPI_DEFAULT_WORDLEN 8
39 * struct spi_slave - Representation of a SPI slave
41 * Drivers are expected to extend this with controller-specific data.
43 * @bus: ID of the bus that the slave is attached to.
44 * @cs: ID of the chip select connected to the slave.
45 * @wordlen: Size of SPI word in number of bits
46 * @max_write_size: If non-zero, the maximum number of bytes which can
47 * be written at once, excluding command bytes.
48 * @memory_map: Address of read-only SPI flash access.
54 unsigned int max_write_size;
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).
86 * This 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)
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);
126 * Free any memory associated with a SPI slave.
128 * @slave: The SPI slave
130 void spi_free_slave(struct spi_slave *slave);
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);
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);
160 * Set the word length for SPI transactions
162 * Set the word length (number of bits per word) for SPI transactions.
164 * @slave: The SPI slave
165 * @wordlen: The number of bits in a word
167 * Returns: 0 on success, -1 on failure.
169 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
174 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
175 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
177 * The source of the outgoing bits is the "dout" parameter and the
178 * destination of the input bits is the "din" parameter. Note that "dout"
179 * and "din" can point to the same memory location, in which case the
180 * input data overwrites the output data (since both are buffered by
181 * temporary variables, this is OK).
183 * spi_xfer() interface:
184 * @slave: The SPI slave which will be sending/receiving the data.
185 * @bitlen: How many bits to write and read.
186 * @dout: Pointer to a string of bits to send out. The bits are
187 * held in a byte array and are sent MSB first.
188 * @din: Pointer to a string of bits that will be filled in.
189 * @flags: A bitwise combination of SPI_XFER_* flags.
191 * Returns: 0 on success, not 0 on failure
193 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
194 void *din, unsigned long flags);
197 * Determine if a SPI chipselect is valid.
198 * This function is provided by the board if the low-level SPI driver
199 * needs it to determine if a given chipselect is actually valid.
201 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
204 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
207 * Activate a SPI chipselect.
208 * This function is provided by the board code when using a driver
209 * that can't control its chipselects automatically (e.g.
210 * common/soft_spi.c). When called, it should activate the chip select
211 * to the device identified by "slave".
213 void spi_cs_activate(struct spi_slave *slave);
216 * Deactivate a SPI chipselect.
217 * This function is provided by the board code when using a driver
218 * that can't control its chipselects automatically (e.g.
219 * common/soft_spi.c). When called, it should deactivate the chip
220 * select to the device identified by "slave".
222 void spi_cs_deactivate(struct spi_slave *slave);
225 * Set transfer speed.
226 * This sets a new speed to be applied for next spi_xfer().
227 * @slave: The SPI slave
228 * @hz: The transfer speed
230 void spi_set_speed(struct spi_slave *slave, uint hz);
233 * Write 8 bits, then read 8 bits.
234 * @slave: The SPI slave we're communicating with
235 * @byte: Byte to be written
237 * Returns: The value that was read, or a negative value on error.
239 * TODO: This function probably shouldn't be inlined.
241 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
243 unsigned char dout[2];
244 unsigned char din[2];
250 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
251 return ret < 0 ? ret : din[1];
255 * Set up a SPI slave for a particular device tree node
257 * This calls spi_setup_slave() with the correct bus number. Call
258 * spi_free_slave() to free it later.
260 * @param blob: Device tree blob
261 * @param node: SPI peripheral node to use
262 * @param cs: Chip select to use
263 * @param max_hz: Maximum SCK rate in Hz (0 for default)
264 * @param mode: Clock polarity, clock phase and other parameters
265 * @return pointer to new spi_slave structure
267 struct spi_slave *spi_setup_slave_fdt(const void *blob, int node,
268 unsigned int cs, unsigned int max_hz, unsigned int mode);