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 33 /* Header byte that marks the start of the message */ 34 #define SPI_PREAMBLE_END_BYTE 0xec 35 36 #define SPI_DEFAULT_WORDLEN 8 37 38 /** 39 * struct spi_slave - Representation of a SPI slave 40 * 41 * Drivers are expected to extend this with controller-specific data. 42 * 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. 49 */ 50 struct spi_slave { 51 unsigned int bus; 52 unsigned int cs; 53 unsigned int wordlen; 54 unsigned int max_write_size; 55 void *memory_map; 56 }; 57 58 /** 59 * Initialization, must be called once on start up. 60 * 61 * TODO: I don't think we really need this. 62 */ 63 void spi_init(void); 64 65 /** 66 * spi_do_alloc_slave - Allocate a new SPI slave (internal) 67 * 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. 70 * 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. 75 */ 76 void *spi_do_alloc_slave(int offset, int size, unsigned int bus, 77 unsigned int cs); 78 79 /** 80 * spi_alloc_slave - Allocate a new SPI slave 81 * 82 * Allocate and zero all fields in the spi slave, and set the bus/chip 83 * select. 84 * 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. 89 */ 90 #define spi_alloc_slave(_struct, bus, cs) \ 91 spi_do_alloc_slave(offsetof(_struct, slave), \ 92 sizeof(_struct), bus, cs) 93 94 /** 95 * spi_alloc_slave_base - Allocate a new SPI slave with no private data 96 * 97 * Allocate and zero all fields in the spi slave, and set the bus/chip 98 * select. 99 * 100 * @bus: Bus ID of the slave chip. 101 * @cs: Chip select ID of the slave chip on the specified bus. 102 */ 103 #define spi_alloc_slave_base(bus, cs) \ 104 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs) 105 106 /** 107 * Set up communications parameters for a SPI slave. 108 * 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 112 * initialized later. 113 * 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. 118 * 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. 121 */ 122 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 123 unsigned int max_hz, unsigned int mode); 124 125 /** 126 * Free any memory associated with a SPI slave. 127 * 128 * @slave: The SPI slave 129 */ 130 void spi_free_slave(struct spi_slave *slave); 131 132 /** 133 * Claim the bus and prepare it for communication with a given slave. 134 * 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. 140 * 141 * @slave: The SPI slave 142 * 143 * Returns: 0 if the bus was claimed successfully, or a negative value 144 * if it wasn't. 145 */ 146 int spi_claim_bus(struct spi_slave *slave); 147 148 /** 149 * Release the SPI bus 150 * 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 153 * appropriate. 154 * 155 * @slave: The SPI slave 156 */ 157 void spi_release_bus(struct spi_slave *slave); 158 159 /** 160 * Set the word length for SPI transactions 161 * 162 * Set the word length (number of bits per word) for SPI transactions. 163 * 164 * @slave: The SPI slave 165 * @wordlen: The number of bits in a word 166 * 167 * Returns: 0 on success, -1 on failure. 168 */ 169 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen); 170 171 /** 172 * SPI transfer 173 * 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. 176 * 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). 182 * 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. 190 * 191 * Returns: 0 on success, not 0 on failure 192 */ 193 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 194 void *din, unsigned long flags); 195 196 /** 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. 200 * 201 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 202 * otherwise. 203 */ 204 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 205 206 /** 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". 212 */ 213 void spi_cs_activate(struct spi_slave *slave); 214 215 /** 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". 221 */ 222 void spi_cs_deactivate(struct spi_slave *slave); 223 224 /** 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 229 */ 230 void spi_set_speed(struct spi_slave *slave, uint hz); 231 232 /** 233 * Write 8 bits, then read 8 bits. 234 * @slave: The SPI slave we're communicating with 235 * @byte: Byte to be written 236 * 237 * Returns: The value that was read, or a negative value on error. 238 * 239 * TODO: This function probably shouldn't be inlined. 240 */ 241 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 242 { 243 unsigned char dout[2]; 244 unsigned char din[2]; 245 int ret; 246 247 dout[0] = byte; 248 dout[1] = 0; 249 250 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 251 return ret < 0 ? ret : din[1]; 252 } 253 254 /** 255 * Set up a SPI slave for a particular device tree node 256 * 257 * This calls spi_setup_slave() with the correct bus number. Call 258 * spi_free_slave() to free it later. 259 * 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 266 */ 267 struct spi_slave *spi_setup_slave_fdt(const void *blob, int node, 268 unsigned int cs, unsigned int max_hz, unsigned int mode); 269 270 #endif /* _SPI_H_ */ 271