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_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 | \ 45 SPI_OPM_RX_QIOF 46 47 /* Header byte that marks the start of the message */ 48 #define SPI_PREAMBLE_END_BYTE 0xec 49 50 #define SPI_DEFAULT_WORDLEN 8 51 52 /** 53 * struct spi_slave - Representation of a SPI slave 54 * 55 * Drivers are expected to extend this with controller-specific data. 56 * 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. 65 */ 66 struct spi_slave { 67 unsigned int bus; 68 unsigned int cs; 69 u8 op_mode_rx; 70 u8 op_mode_tx; 71 unsigned int wordlen; 72 unsigned int max_write_size; 73 void *memory_map; 74 }; 75 76 /** 77 * Initialization, must be called once on start up. 78 * 79 * TODO: I don't think we really need this. 80 */ 81 void spi_init(void); 82 83 /** 84 * spi_do_alloc_slave - Allocate a new SPI slave (internal) 85 * 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. 88 * 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. 93 */ 94 void *spi_do_alloc_slave(int offset, int size, unsigned int bus, 95 unsigned int cs); 96 97 /** 98 * spi_alloc_slave - Allocate a new SPI slave 99 * 100 * Allocate and zero all fields in the spi slave, and set the bus/chip 101 * select. 102 * 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. 107 */ 108 #define spi_alloc_slave(_struct, bus, cs) \ 109 spi_do_alloc_slave(offsetof(_struct, slave), \ 110 sizeof(_struct), bus, cs) 111 112 /** 113 * spi_alloc_slave_base - Allocate a new SPI slave with no private data 114 * 115 * Allocate and zero all fields in the spi slave, and set the bus/chip 116 * select. 117 * 118 * @bus: Bus ID of the slave chip. 119 * @cs: Chip select ID of the slave chip on the specified bus. 120 */ 121 #define spi_alloc_slave_base(bus, cs) \ 122 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs) 123 124 /** 125 * Set up communications parameters for a SPI slave. 126 * 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 130 * initialized later. 131 * 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. 136 * 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. 139 */ 140 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 141 unsigned int max_hz, unsigned int mode); 142 143 /** 144 * Free any memory associated with a SPI slave. 145 * 146 * @slave: The SPI slave 147 */ 148 void spi_free_slave(struct spi_slave *slave); 149 150 /** 151 * Claim the bus and prepare it for communication with a given slave. 152 * 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. 158 * 159 * @slave: The SPI slave 160 * 161 * Returns: 0 if the bus was claimed successfully, or a negative value 162 * if it wasn't. 163 */ 164 int spi_claim_bus(struct spi_slave *slave); 165 166 /** 167 * Release the SPI bus 168 * 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 171 * appropriate. 172 * 173 * @slave: The SPI slave 174 */ 175 void spi_release_bus(struct spi_slave *slave); 176 177 /** 178 * Set the word length for SPI transactions 179 * 180 * Set the word length (number of bits per word) for SPI transactions. 181 * 182 * @slave: The SPI slave 183 * @wordlen: The number of bits in a word 184 * 185 * Returns: 0 on success, -1 on failure. 186 */ 187 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen); 188 189 /** 190 * SPI transfer 191 * 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. 194 * 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). 200 * 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. 208 * 209 * Returns: 0 on success, not 0 on failure 210 */ 211 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 212 void *din, unsigned long flags); 213 214 /** 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. 218 * 219 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 220 * otherwise. 221 */ 222 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 223 224 /** 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". 230 */ 231 void spi_cs_activate(struct spi_slave *slave); 232 233 /** 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". 239 */ 240 void spi_cs_deactivate(struct spi_slave *slave); 241 242 /** 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 247 */ 248 void spi_set_speed(struct spi_slave *slave, uint hz); 249 250 /** 251 * Write 8 bits, then read 8 bits. 252 * @slave: The SPI slave we're communicating with 253 * @byte: Byte to be written 254 * 255 * Returns: The value that was read, or a negative value on error. 256 * 257 * TODO: This function probably shouldn't be inlined. 258 */ 259 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 260 { 261 unsigned char dout[2]; 262 unsigned char din[2]; 263 int ret; 264 265 dout[0] = byte; 266 dout[1] = 0; 267 268 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 269 return ret < 0 ? ret : din[1]; 270 } 271 272 /** 273 * Set up a SPI slave for a particular device tree node 274 * 275 * This calls spi_setup_slave() with the correct bus number. Call 276 * spi_free_slave() to free it later. 277 * 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 282 */ 283 struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node, 284 int spi_node); 285 286 /** 287 * spi_base_setup_slave_fdt() - helper function to set up a SPI slace 288 * 289 * This decodes SPI properties from the slave node to determine the 290 * chip select and SPI parameters. 291 * 292 * @blob: Device tree blob 293 * @busnum: Bus number to use 294 * @node: Device tree node for the SPI bus 295 */ 296 struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum, 297 int node); 298 299 #endif /* _SPI_H_ */ 300