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 RX operation modes */
35 #define SPI_OPM_RX_AS 1 << 0
36 #define SPI_OPM_RX_DOUT 1 << 1
37 #define SPI_OPM_RX_DIO 1 << 2
38 #define SPI_OPM_RX_EXTN SPI_OPM_RX_AS | SPI_OPM_RX_DOUT | SPI_OPM_RX_DIO
40 /* Header byte that marks the start of the message */
41 #define SPI_PREAMBLE_END_BYTE 0xec
43 #define SPI_DEFAULT_WORDLEN 8
46 * struct spi_slave - Representation of a SPI slave
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.
52 * @op_mode_rx: SPI RX operation mode.
53 * @wordlen: Size of SPI word in number of bits
54 * @max_write_size: If non-zero, the maximum number of bytes which can
55 * be written at once, excluding command bytes.
56 * @memory_map: Address of read-only SPI flash access.
63 unsigned int max_write_size;
68 * Initialization, must be called once on start up.
70 * TODO: I don't think we really need this.
75 * spi_do_alloc_slave - Allocate a new SPI slave (internal)
77 * Allocate and zero all fields in the spi slave, and set the bus/chip
78 * select. Use the helper macro spi_alloc_slave() to call this.
80 * @offset: Offset of struct spi_slave within slave structure.
81 * @size: Size of slave structure.
82 * @bus: Bus ID of the slave chip.
83 * @cs: Chip select ID of the slave chip on the specified bus.
85 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
89 * spi_alloc_slave - Allocate a new SPI slave
91 * Allocate and zero all fields in the spi slave, and set the bus/chip
94 * @_struct: Name of structure to allocate (e.g. struct tegra_spi).
95 * This structure must contain a member 'struct spi_slave *slave'.
96 * @bus: Bus ID of the slave chip.
97 * @cs: Chip select ID of the slave chip on the specified bus.
99 #define spi_alloc_slave(_struct, bus, cs) \
100 spi_do_alloc_slave(offsetof(_struct, slave), \
101 sizeof(_struct), bus, cs)
104 * spi_alloc_slave_base - Allocate a new SPI slave with no private data
106 * Allocate and zero all fields in the spi slave, and set the bus/chip
109 * @bus: Bus ID of the slave chip.
110 * @cs: Chip select ID of the slave chip on the specified bus.
112 #define spi_alloc_slave_base(bus, cs) \
113 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
116 * Set up communications parameters for a SPI slave.
118 * This must be called once for each slave. Note that this function
119 * usually doesn't touch any actual hardware, it only initializes the
120 * contents of spi_slave so that the hardware can be easily
123 * @bus: Bus ID of the slave chip.
124 * @cs: Chip select ID of the slave chip on the specified bus.
125 * @max_hz: Maximum SCK rate in Hz.
126 * @mode: Clock polarity, clock phase and other parameters.
128 * Returns: A spi_slave reference that can be used in subsequent SPI
129 * calls, or NULL if one or more of the parameters are not supported.
131 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
132 unsigned int max_hz, unsigned int mode);
135 * Free any memory associated with a SPI slave.
137 * @slave: The SPI slave
139 void spi_free_slave(struct spi_slave *slave);
142 * Claim the bus and prepare it for communication with a given slave.
144 * This must be called before doing any transfers with a SPI slave. It
145 * will enable and initialize any SPI hardware as necessary, and make
146 * sure that the SCK line is in the correct idle state. It is not
147 * allowed to claim the same bus for several slaves without releasing
148 * the bus in between.
150 * @slave: The SPI slave
152 * Returns: 0 if the bus was claimed successfully, or a negative value
155 int spi_claim_bus(struct spi_slave *slave);
158 * Release the SPI bus
160 * This must be called once for every call to spi_claim_bus() after
161 * all transfers have finished. It may disable any SPI hardware as
164 * @slave: The SPI slave
166 void spi_release_bus(struct spi_slave *slave);
169 * Set the word length for SPI transactions
171 * Set the word length (number of bits per word) for SPI transactions.
173 * @slave: The SPI slave
174 * @wordlen: The number of bits in a word
176 * Returns: 0 on success, -1 on failure.
178 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
183 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
184 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
186 * The source of the outgoing bits is the "dout" parameter and the
187 * destination of the input bits is the "din" parameter. Note that "dout"
188 * and "din" can point to the same memory location, in which case the
189 * input data overwrites the output data (since both are buffered by
190 * temporary variables, this is OK).
192 * spi_xfer() interface:
193 * @slave: The SPI slave which will be sending/receiving the data.
194 * @bitlen: How many bits to write and read.
195 * @dout: Pointer to a string of bits to send out. The bits are
196 * held in a byte array and are sent MSB first.
197 * @din: Pointer to a string of bits that will be filled in.
198 * @flags: A bitwise combination of SPI_XFER_* flags.
200 * Returns: 0 on success, not 0 on failure
202 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
203 void *din, unsigned long flags);
206 * Determine if a SPI chipselect is valid.
207 * This function is provided by the board if the low-level SPI driver
208 * needs it to determine if a given chipselect is actually valid.
210 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
213 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
216 * Activate 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 activate the chip select
220 * to the device identified by "slave".
222 void spi_cs_activate(struct spi_slave *slave);
225 * Deactivate 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 deactivate the chip
229 * select to the device identified by "slave".
231 void spi_cs_deactivate(struct spi_slave *slave);
234 * Set transfer speed.
235 * This sets a new speed to be applied for next spi_xfer().
236 * @slave: The SPI slave
237 * @hz: The transfer speed
239 void spi_set_speed(struct spi_slave *slave, uint hz);
242 * Write 8 bits, then read 8 bits.
243 * @slave: The SPI slave we're communicating with
244 * @byte: Byte to be written
246 * Returns: The value that was read, or a negative value on error.
248 * TODO: This function probably shouldn't be inlined.
250 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
252 unsigned char dout[2];
253 unsigned char din[2];
259 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
260 return ret < 0 ? ret : din[1];
264 * Set up a SPI slave for a particular device tree node
266 * This calls spi_setup_slave() with the correct bus number. Call
267 * spi_free_slave() to free it later.
269 * @param blob: Device tree blob
270 * @param slave_node: Slave node to use
271 * @param spi_node: SPI peripheral node to use
272 * @return pointer to new spi_slave structure
274 struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node,
278 * spi_base_setup_slave_fdt() - helper function to set up a SPI slace
280 * This decodes SPI properties from the slave node to determine the
281 * chip select and SPI parameters.
283 * @blob: Device tree blob
284 * @busnum: Bus number to use
285 * @node: Device tree node for the SPI bus
287 struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum,