1 /* 2 * Common SPI Interface: Controller-specific definitions 3 * 4 * (C) Copyright 2001 5 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com. 6 * 7 * SPDX-License-Identifier: GPL-2.0+ 8 */ 9 10 #ifndef _SPI_H_ 11 #define _SPI_H_ 12 13 /* SPI mode flags */ 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 */ 26 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) 33 34 /* Header byte that marks the start of the message */ 35 #define SPI_PREAMBLE_END_BYTE 0xec 36 37 #define SPI_DEFAULT_WORDLEN 8 38 39 /** 40 * struct spi_slave - Representation of a SPI slave 41 * 42 * Drivers are expected to extend this with controller-specific data. 43 * 44 * @bus: ID of the bus that the slave is attached to. 45 * @cs: ID of the chip select connected to the slave. 46 * @wordlen: Size of SPI word in number of bits 47 * @max_write_size: If non-zero, the maximum number of bytes which can 48 * be written at once, excluding command bytes. 49 * @memory_map: Address of read-only SPI flash access. 50 */ 51 struct spi_slave { 52 unsigned int bus; 53 unsigned int cs; 54 unsigned int wordlen; 55 unsigned int max_write_size; 56 void *memory_map; 57 }; 58 59 /** 60 * Initialization, must be called once on start up. 61 * 62 * TODO: I don't think we really need this. 63 */ 64 void spi_init(void); 65 66 /** 67 * spi_do_alloc_slave - Allocate a new SPI slave (internal) 68 * 69 * Allocate and zero all fields in the spi slave, and set the bus/chip 70 * select. Use the helper macro spi_alloc_slave() to call this. 71 * 72 * @offset: Offset of struct spi_slave within slave structure. 73 * @size: Size of slave structure. 74 * @bus: Bus ID of the slave chip. 75 * @cs: Chip select ID of the slave chip on the specified bus. 76 */ 77 void *spi_do_alloc_slave(int offset, int size, unsigned int bus, 78 unsigned int cs); 79 80 /** 81 * spi_alloc_slave - Allocate a new SPI slave 82 * 83 * Allocate and zero all fields in the spi slave, and set the bus/chip 84 * select. 85 * 86 * @_struct: Name of structure to allocate (e.g. struct tegra_spi). 87 * This structure must contain a member 'struct spi_slave *slave'. 88 * @bus: Bus ID of the slave chip. 89 * @cs: Chip select ID of the slave chip on the specified bus. 90 */ 91 #define spi_alloc_slave(_struct, bus, cs) \ 92 spi_do_alloc_slave(offsetof(_struct, slave), \ 93 sizeof(_struct), bus, cs) 94 95 /** 96 * spi_alloc_slave_base - Allocate a new SPI slave with no private data 97 * 98 * Allocate and zero all fields in the spi slave, and set the bus/chip 99 * select. 100 * 101 * @bus: Bus ID of the slave chip. 102 * @cs: Chip select ID of the slave chip on the specified bus. 103 */ 104 #define spi_alloc_slave_base(bus, cs) \ 105 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs) 106 107 /** 108 * Set up communications parameters for a SPI slave. 109 * 110 * This must be called once for each slave. Note that this function 111 * usually doesn't touch any actual hardware, it only initializes the 112 * contents of spi_slave so that the hardware can be easily 113 * initialized later. 114 * 115 * @bus: Bus ID of the slave chip. 116 * @cs: Chip select ID of the slave chip on the specified bus. 117 * @max_hz: Maximum SCK rate in Hz. 118 * @mode: Clock polarity, clock phase and other parameters. 119 * 120 * Returns: A spi_slave reference that can be used in subsequent SPI 121 * calls, or NULL if one or more of the parameters are not supported. 122 */ 123 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 124 unsigned int max_hz, unsigned int mode); 125 126 /** 127 * Free any memory associated with a SPI slave. 128 * 129 * @slave: The SPI slave 130 */ 131 void spi_free_slave(struct spi_slave *slave); 132 133 /** 134 * Claim the bus and prepare it for communication with a given slave. 135 * 136 * This must be called before doing any transfers with a SPI slave. It 137 * will enable and initialize any SPI hardware as necessary, and make 138 * sure that the SCK line is in the correct idle state. It is not 139 * allowed to claim the same bus for several slaves without releasing 140 * the bus in between. 141 * 142 * @slave: The SPI slave 143 * 144 * Returns: 0 if the bus was claimed successfully, or a negative value 145 * if it wasn't. 146 */ 147 int spi_claim_bus(struct spi_slave *slave); 148 149 /** 150 * Release the SPI bus 151 * 152 * This must be called once for every call to spi_claim_bus() after 153 * all transfers have finished. It may disable any SPI hardware as 154 * appropriate. 155 * 156 * @slave: The SPI slave 157 */ 158 void spi_release_bus(struct spi_slave *slave); 159 160 /** 161 * Set the word length for SPI transactions 162 * 163 * Set the word length (number of bits per word) for SPI transactions. 164 * 165 * @slave: The SPI slave 166 * @wordlen: The number of bits in a word 167 * 168 * Returns: 0 on success, -1 on failure. 169 */ 170 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen); 171 172 /** 173 * SPI transfer 174 * 175 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks 176 * "bitlen" bits in the SPI MISO port. That's just the way SPI works. 177 * 178 * The source of the outgoing bits is the "dout" parameter and the 179 * destination of the input bits is the "din" parameter. Note that "dout" 180 * and "din" can point to the same memory location, in which case the 181 * input data overwrites the output data (since both are buffered by 182 * temporary variables, this is OK). 183 * 184 * spi_xfer() interface: 185 * @slave: The SPI slave which will be sending/receiving the data. 186 * @bitlen: How many bits to write and read. 187 * @dout: Pointer to a string of bits to send out. The bits are 188 * held in a byte array and are sent MSB first. 189 * @din: Pointer to a string of bits that will be filled in. 190 * @flags: A bitwise combination of SPI_XFER_* flags. 191 * 192 * Returns: 0 on success, not 0 on failure 193 */ 194 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 195 void *din, unsigned long flags); 196 197 /** 198 * Determine if a SPI chipselect is valid. 199 * This function is provided by the board if the low-level SPI driver 200 * needs it to determine if a given chipselect is actually valid. 201 * 202 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 203 * otherwise. 204 */ 205 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 206 207 /** 208 * Activate a SPI chipselect. 209 * This function is provided by the board code when using a driver 210 * that can't control its chipselects automatically (e.g. 211 * common/soft_spi.c). When called, it should activate the chip select 212 * to the device identified by "slave". 213 */ 214 void spi_cs_activate(struct spi_slave *slave); 215 216 /** 217 * Deactivate a SPI chipselect. 218 * This function is provided by the board code when using a driver 219 * that can't control its chipselects automatically (e.g. 220 * common/soft_spi.c). When called, it should deactivate the chip 221 * select to the device identified by "slave". 222 */ 223 void spi_cs_deactivate(struct spi_slave *slave); 224 225 /** 226 * Set transfer speed. 227 * This sets a new speed to be applied for next spi_xfer(). 228 * @slave: The SPI slave 229 * @hz: The transfer speed 230 */ 231 void spi_set_speed(struct spi_slave *slave, uint hz); 232 233 /** 234 * Write 8 bits, then read 8 bits. 235 * @slave: The SPI slave we're communicating with 236 * @byte: Byte to be written 237 * 238 * Returns: The value that was read, or a negative value on error. 239 * 240 * TODO: This function probably shouldn't be inlined. 241 */ 242 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 243 { 244 unsigned char dout[2]; 245 unsigned char din[2]; 246 int ret; 247 248 dout[0] = byte; 249 dout[1] = 0; 250 251 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 252 return ret < 0 ? ret : din[1]; 253 } 254 255 /** 256 * Set up a SPI slave for a particular device tree node 257 * 258 * This calls spi_setup_slave() with the correct bus number. Call 259 * spi_free_slave() to free it later. 260 * 261 * @param blob: Device tree blob 262 * @param node: SPI peripheral node to use 263 * @param cs: Chip select to use 264 * @param max_hz: Maximum SCK rate in Hz (0 for default) 265 * @param mode: Clock polarity, clock phase and other parameters 266 * @return pointer to new spi_slave structure 267 */ 268 struct spi_slave *spi_setup_slave_fdt(const void *blob, int node, 269 unsigned int cs, unsigned int max_hz, unsigned int mode); 270 271 #endif /* _SPI_H_ */ 272