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_QIOF 1 << 4
43 #define SPI_OPM_RX_EXTN SPI_OPM_RX_AS | SPI_OPM_RX_DOUT | \
44 SPI_OPM_RX_DIO | SPI_OPM_RX_QOF | \
47 /* Header byte that marks the start of the message */
48 #define SPI_PREAMBLE_END_BYTE 0xec
50 #define SPI_DEFAULT_WORDLEN 8
53 * struct spi_slave - Representation of a SPI slave
55 * Drivers are expected to extend this with controller-specific data.
57 * @bus: ID of the bus that the slave is attached to.
58 * @cs: ID of the chip select connected to the slave.
59 * @op_mode_rx: SPI RX operation mode.
60 * @op_mode_tx: SPI TX operation mode.
61 * @wordlen: Size of SPI word in number of bits
62 * @max_write_size: If non-zero, the maximum number of bytes which can
63 * be written at once, excluding command bytes.
64 * @memory_map: Address of read-only SPI flash access.
72 unsigned int max_write_size;
77 * Initialization, must be called once on start up.
79 * TODO: I don't think we really need this.
84 * spi_do_alloc_slave - Allocate a new SPI slave (internal)
86 * Allocate and zero all fields in the spi slave, and set the bus/chip
87 * select. Use the helper macro spi_alloc_slave() to call this.
89 * @offset: Offset of struct spi_slave within slave structure.
90 * @size: Size of slave structure.
91 * @bus: Bus ID of the slave chip.
92 * @cs: Chip select ID of the slave chip on the specified bus.
94 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
98 * spi_alloc_slave - Allocate a new SPI slave
100 * Allocate and zero all fields in the spi slave, and set the bus/chip
103 * @_struct: Name of structure to allocate (e.g. struct tegra_spi).
104 * This structure must contain a member 'struct spi_slave *slave'.
105 * @bus: Bus ID of the slave chip.
106 * @cs: Chip select ID of the slave chip on the specified bus.
108 #define spi_alloc_slave(_struct, bus, cs) \
109 spi_do_alloc_slave(offsetof(_struct, slave), \
110 sizeof(_struct), bus, cs)
113 * spi_alloc_slave_base - Allocate a new SPI slave with no private data
115 * Allocate and zero all fields in the spi slave, and set the bus/chip
118 * @bus: Bus ID of the slave chip.
119 * @cs: Chip select ID of the slave chip on the specified bus.
121 #define spi_alloc_slave_base(bus, cs) \
122 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
125 * Set up communications parameters for a SPI slave.
127 * This must be called once for each slave. Note that this function
128 * usually doesn't touch any actual hardware, it only initializes the
129 * contents of spi_slave so that the hardware can be easily
132 * @bus: Bus ID of the slave chip.
133 * @cs: Chip select ID of the slave chip on the specified bus.
134 * @max_hz: Maximum SCK rate in Hz.
135 * @mode: Clock polarity, clock phase and other parameters.
137 * Returns: A spi_slave reference that can be used in subsequent SPI
138 * calls, or NULL if one or more of the parameters are not supported.
140 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
141 unsigned int max_hz, unsigned int mode);
144 * Free any memory associated with a SPI slave.
146 * @slave: The SPI slave
148 void spi_free_slave(struct spi_slave *slave);
151 * Claim the bus and prepare it for communication with a given slave.
153 * This must be called before doing any transfers with a SPI slave. It
154 * will enable and initialize any SPI hardware as necessary, and make
155 * sure that the SCK line is in the correct idle state. It is not
156 * allowed to claim the same bus for several slaves without releasing
157 * the bus in between.
159 * @slave: The SPI slave
161 * Returns: 0 if the bus was claimed successfully, or a negative value
164 int spi_claim_bus(struct spi_slave *slave);
167 * Release the SPI bus
169 * This must be called once for every call to spi_claim_bus() after
170 * all transfers have finished. It may disable any SPI hardware as
173 * @slave: The SPI slave
175 void spi_release_bus(struct spi_slave *slave);
178 * Set the word length for SPI transactions
180 * Set the word length (number of bits per word) for SPI transactions.
182 * @slave: The SPI slave
183 * @wordlen: The number of bits in a word
185 * Returns: 0 on success, -1 on failure.
187 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
192 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
193 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
195 * The source of the outgoing bits is the "dout" parameter and the
196 * destination of the input bits is the "din" parameter. Note that "dout"
197 * and "din" can point to the same memory location, in which case the
198 * input data overwrites the output data (since both are buffered by
199 * temporary variables, this is OK).
201 * spi_xfer() interface:
202 * @slave: The SPI slave which will be sending/receiving the data.
203 * @bitlen: How many bits to write and read.
204 * @dout: Pointer to a string of bits to send out. The bits are
205 * held in a byte array and are sent MSB first.
206 * @din: Pointer to a string of bits that will be filled in.
207 * @flags: A bitwise combination of SPI_XFER_* flags.
209 * Returns: 0 on success, not 0 on failure
211 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
212 void *din, unsigned long flags);
215 * Determine if a SPI chipselect is valid.
216 * This function is provided by the board if the low-level SPI driver
217 * needs it to determine if a given chipselect is actually valid.
219 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
222 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
225 * Activate a SPI chipselect.
226 * This function is provided by the board code when using a driver
227 * that can't control its chipselects automatically (e.g.
228 * common/soft_spi.c). When called, it should activate the chip select
229 * to the device identified by "slave".
231 void spi_cs_activate(struct spi_slave *slave);
234 * Deactivate a SPI chipselect.
235 * This function is provided by the board code when using a driver
236 * that can't control its chipselects automatically (e.g.
237 * common/soft_spi.c). When called, it should deactivate the chip
238 * select to the device identified by "slave".
240 void spi_cs_deactivate(struct spi_slave *slave);
243 * Set transfer speed.
244 * This sets a new speed to be applied for next spi_xfer().
245 * @slave: The SPI slave
246 * @hz: The transfer speed
248 void spi_set_speed(struct spi_slave *slave, uint hz);
251 * Write 8 bits, then read 8 bits.
252 * @slave: The SPI slave we're communicating with
253 * @byte: Byte to be written
255 * Returns: The value that was read, or a negative value on error.
257 * TODO: This function probably shouldn't be inlined.
259 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
261 unsigned char dout[2];
262 unsigned char din[2];
268 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
269 return ret < 0 ? ret : din[1];
273 * Set up a SPI slave for a particular device tree node
275 * This calls spi_setup_slave() with the correct bus number. Call
276 * spi_free_slave() to free it later.
278 * @param blob: Device tree blob
279 * @param slave_node: Slave node to use
280 * @param spi_node: SPI peripheral node to use
281 * @return pointer to new spi_slave structure
283 struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node,
287 * spi_base_setup_slave_fdt() - helper function to set up a SPI slace
289 * This decodes SPI properties from the slave node to determine the
290 * chip select and SPI parameters.
292 * @blob: Device tree blob
293 * @busnum: Bus number to use
294 * @node: Device tree node for the SPI bus
296 struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum,