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 /* SPI TX operation modes */ 35 #define SPI_OPM_TX_QPP 1 << 0 36 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 44 45 /* Header byte that marks the start of the message */ 46 #define SPI_PREAMBLE_END_BYTE 0xec 47 48 #define SPI_DEFAULT_WORDLEN 8 49 50 /** 51 * struct spi_slave - Representation of a SPI slave 52 * 53 * Drivers are expected to extend this with controller-specific data. 54 * 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. 63 */ 64 struct spi_slave { 65 unsigned int bus; 66 unsigned int cs; 67 u8 op_mode_rx; 68 u8 op_mode_tx; 69 unsigned int wordlen; 70 unsigned int max_write_size; 71 void *memory_map; 72 }; 73 74 /** 75 * Initialization, must be called once on start up. 76 * 77 * TODO: I don't think we really need this. 78 */ 79 void spi_init(void); 80 81 /** 82 * spi_do_alloc_slave - Allocate a new SPI slave (internal) 83 * 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. 86 * 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. 91 */ 92 void *spi_do_alloc_slave(int offset, int size, unsigned int bus, 93 unsigned int cs); 94 95 /** 96 * spi_alloc_slave - Allocate a new SPI slave 97 * 98 * Allocate and zero all fields in the spi slave, and set the bus/chip 99 * select. 100 * 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. 105 */ 106 #define spi_alloc_slave(_struct, bus, cs) \ 107 spi_do_alloc_slave(offsetof(_struct, slave), \ 108 sizeof(_struct), bus, cs) 109 110 /** 111 * spi_alloc_slave_base - Allocate a new SPI slave with no private data 112 * 113 * Allocate and zero all fields in the spi slave, and set the bus/chip 114 * select. 115 * 116 * @bus: Bus ID of the slave chip. 117 * @cs: Chip select ID of the slave chip on the specified bus. 118 */ 119 #define spi_alloc_slave_base(bus, cs) \ 120 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs) 121 122 /** 123 * Set up communications parameters for a SPI slave. 124 * 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 128 * initialized later. 129 * 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. 134 * 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. 137 */ 138 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 139 unsigned int max_hz, unsigned int mode); 140 141 /** 142 * Free any memory associated with a SPI slave. 143 * 144 * @slave: The SPI slave 145 */ 146 void spi_free_slave(struct spi_slave *slave); 147 148 /** 149 * Claim the bus and prepare it for communication with a given slave. 150 * 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. 156 * 157 * @slave: The SPI slave 158 * 159 * Returns: 0 if the bus was claimed successfully, or a negative value 160 * if it wasn't. 161 */ 162 int spi_claim_bus(struct spi_slave *slave); 163 164 /** 165 * Release the SPI bus 166 * 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 169 * appropriate. 170 * 171 * @slave: The SPI slave 172 */ 173 void spi_release_bus(struct spi_slave *slave); 174 175 /** 176 * Set the word length for SPI transactions 177 * 178 * Set the word length (number of bits per word) for SPI transactions. 179 * 180 * @slave: The SPI slave 181 * @wordlen: The number of bits in a word 182 * 183 * Returns: 0 on success, -1 on failure. 184 */ 185 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen); 186 187 /** 188 * SPI transfer 189 * 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. 192 * 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). 198 * 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. 206 * 207 * Returns: 0 on success, not 0 on failure 208 */ 209 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 210 void *din, unsigned long flags); 211 212 /** 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. 216 * 217 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 218 * otherwise. 219 */ 220 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 221 222 /** 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". 228 */ 229 void spi_cs_activate(struct spi_slave *slave); 230 231 /** 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". 237 */ 238 void spi_cs_deactivate(struct spi_slave *slave); 239 240 /** 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 245 */ 246 void spi_set_speed(struct spi_slave *slave, uint hz); 247 248 /** 249 * Write 8 bits, then read 8 bits. 250 * @slave: The SPI slave we're communicating with 251 * @byte: Byte to be written 252 * 253 * Returns: The value that was read, or a negative value on error. 254 * 255 * TODO: This function probably shouldn't be inlined. 256 */ 257 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 258 { 259 unsigned char dout[2]; 260 unsigned char din[2]; 261 int ret; 262 263 dout[0] = byte; 264 dout[1] = 0; 265 266 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 267 return ret < 0 ? ret : din[1]; 268 } 269 270 /** 271 * Set up a SPI slave for a particular device tree node 272 * 273 * This calls spi_setup_slave() with the correct bus number. Call 274 * spi_free_slave() to free it later. 275 * 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 280 */ 281 struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node, 282 int spi_node); 283 284 /** 285 * spi_base_setup_slave_fdt() - helper function to set up a SPI slace 286 * 287 * This decodes SPI properties from the slave node to determine the 288 * chip select and SPI parameters. 289 * 290 * @blob: Device tree blob 291 * @busnum: Bus number to use 292 * @node: Device tree node for the SPI bus 293 */ 294 struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum, 295 int node); 296 297 #endif /* _SPI_H_ */ 298