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 */
32 #define SPI_XFER_ONCE (SPI_XFER_BEGIN | SPI_XFER_END)
34 /* SPI TX operation modes */
35 #define SPI_OPM_TX_QPP 1 << 0
37 /* SPI RX operation modes */
38 #define SPI_OPM_RX_AS 1 << 0
39 #define SPI_OPM_RX_DOUT 1 << 1
40 #define SPI_OPM_RX_DIO 1 << 2
41 #define SPI_OPM_RX_QOF 1 << 3
42 #define SPI_OPM_RX_EXTN SPI_OPM_RX_AS | SPI_OPM_RX_DOUT | \
43 SPI_OPM_RX_DIO | SPI_OPM_RX_QOF
45 /* Header byte that marks the start of the message */
46 #define SPI_PREAMBLE_END_BYTE 0xec
48 #define SPI_DEFAULT_WORDLEN 8
51 * struct spi_slave - Representation of a SPI slave
53 * Drivers are expected to extend this with controller-specific data.
55 * @bus: ID of the bus that the slave is attached to.
56 * @cs: ID of the chip select connected to the slave.
57 * @op_mode_rx: SPI RX operation mode.
58 * @op_mode_tx: SPI TX operation mode.
59 * @wordlen: Size of SPI word in number of bits
60 * @max_write_size: If non-zero, the maximum number of bytes which can
61 * be written at once, excluding command bytes.
62 * @memory_map: Address of read-only SPI flash access.
70 unsigned int max_write_size;
75 * Initialization, must be called once on start up.
77 * TODO: I don't think we really need this.
82 * spi_do_alloc_slave - Allocate a new SPI slave (internal)
84 * Allocate and zero all fields in the spi slave, and set the bus/chip
85 * select. Use the helper macro spi_alloc_slave() to call this.
87 * @offset: Offset of struct spi_slave within slave structure.
88 * @size: Size of slave structure.
89 * @bus: Bus ID of the slave chip.
90 * @cs: Chip select ID of the slave chip on the specified bus.
92 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
96 * spi_alloc_slave - Allocate a new SPI slave
98 * Allocate and zero all fields in the spi slave, and set the bus/chip
101 * @_struct: Name of structure to allocate (e.g. struct tegra_spi).
102 * This structure must contain a member 'struct spi_slave *slave'.
103 * @bus: Bus ID of the slave chip.
104 * @cs: Chip select ID of the slave chip on the specified bus.
106 #define spi_alloc_slave(_struct, bus, cs) \
107 spi_do_alloc_slave(offsetof(_struct, slave), \
108 sizeof(_struct), bus, cs)
111 * spi_alloc_slave_base - Allocate a new SPI slave with no private data
113 * Allocate and zero all fields in the spi slave, and set the bus/chip
116 * @bus: Bus ID of the slave chip.
117 * @cs: Chip select ID of the slave chip on the specified bus.
119 #define spi_alloc_slave_base(bus, cs) \
120 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
123 * Set up communications parameters for a SPI slave.
125 * This must be called once for each slave. Note that this function
126 * usually doesn't touch any actual hardware, it only initializes the
127 * contents of spi_slave so that the hardware can be easily
130 * @bus: Bus ID of the slave chip.
131 * @cs: Chip select ID of the slave chip on the specified bus.
132 * @max_hz: Maximum SCK rate in Hz.
133 * @mode: Clock polarity, clock phase and other parameters.
135 * Returns: A spi_slave reference that can be used in subsequent SPI
136 * calls, or NULL if one or more of the parameters are not supported.
138 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
139 unsigned int max_hz, unsigned int mode);
142 * Free any memory associated with a SPI slave.
144 * @slave: The SPI slave
146 void spi_free_slave(struct spi_slave *slave);
149 * Claim the bus and prepare it for communication with a given slave.
151 * This must be called before doing any transfers with a SPI slave. It
152 * will enable and initialize any SPI hardware as necessary, and make
153 * sure that the SCK line is in the correct idle state. It is not
154 * allowed to claim the same bus for several slaves without releasing
155 * the bus in between.
157 * @slave: The SPI slave
159 * Returns: 0 if the bus was claimed successfully, or a negative value
162 int spi_claim_bus(struct spi_slave *slave);
165 * Release the SPI bus
167 * This must be called once for every call to spi_claim_bus() after
168 * all transfers have finished. It may disable any SPI hardware as
171 * @slave: The SPI slave
173 void spi_release_bus(struct spi_slave *slave);
176 * Set the word length for SPI transactions
178 * Set the word length (number of bits per word) for SPI transactions.
180 * @slave: The SPI slave
181 * @wordlen: The number of bits in a word
183 * Returns: 0 on success, -1 on failure.
185 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
190 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
191 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
193 * The source of the outgoing bits is the "dout" parameter and the
194 * destination of the input bits is the "din" parameter. Note that "dout"
195 * and "din" can point to the same memory location, in which case the
196 * input data overwrites the output data (since both are buffered by
197 * temporary variables, this is OK).
199 * spi_xfer() interface:
200 * @slave: The SPI slave which will be sending/receiving the data.
201 * @bitlen: How many bits to write and read.
202 * @dout: Pointer to a string of bits to send out. The bits are
203 * held in a byte array and are sent MSB first.
204 * @din: Pointer to a string of bits that will be filled in.
205 * @flags: A bitwise combination of SPI_XFER_* flags.
207 * Returns: 0 on success, not 0 on failure
209 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
210 void *din, unsigned long flags);
213 * Determine if a SPI chipselect is valid.
214 * This function is provided by the board if the low-level SPI driver
215 * needs it to determine if a given chipselect is actually valid.
217 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
220 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
223 * Activate a SPI chipselect.
224 * This function is provided by the board code when using a driver
225 * that can't control its chipselects automatically (e.g.
226 * common/soft_spi.c). When called, it should activate the chip select
227 * to the device identified by "slave".
229 void spi_cs_activate(struct spi_slave *slave);
232 * Deactivate a SPI chipselect.
233 * This function is provided by the board code when using a driver
234 * that can't control its chipselects automatically (e.g.
235 * common/soft_spi.c). When called, it should deactivate the chip
236 * select to the device identified by "slave".
238 void spi_cs_deactivate(struct spi_slave *slave);
241 * Set transfer speed.
242 * This sets a new speed to be applied for next spi_xfer().
243 * @slave: The SPI slave
244 * @hz: The transfer speed
246 void spi_set_speed(struct spi_slave *slave, uint hz);
249 * Write 8 bits, then read 8 bits.
250 * @slave: The SPI slave we're communicating with
251 * @byte: Byte to be written
253 * Returns: The value that was read, or a negative value on error.
255 * TODO: This function probably shouldn't be inlined.
257 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
259 unsigned char dout[2];
260 unsigned char din[2];
266 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
267 return ret < 0 ? ret : din[1];
271 * Set up a SPI slave for a particular device tree node
273 * This calls spi_setup_slave() with the correct bus number. Call
274 * spi_free_slave() to free it later.
276 * @param blob: Device tree blob
277 * @param slave_node: Slave node to use
278 * @param spi_node: SPI peripheral node to use
279 * @return pointer to new spi_slave structure
281 struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node,
285 * spi_base_setup_slave_fdt() - helper function to set up a SPI slace
287 * This decodes SPI properties from the slave node to determine the
288 * chip select and SPI parameters.
290 * @blob: Device tree blob
291 * @busnum: Bus number to use
292 * @node: Device tree node for the SPI bus
294 struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum,