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 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 39 40 /* Header byte that marks the start of the message */ 41 #define SPI_PREAMBLE_END_BYTE 0xec 42 43 #define SPI_DEFAULT_WORDLEN 8 44 45 /** 46 * struct spi_slave - Representation of a SPI slave 47 * 48 * Drivers are expected to extend this with controller-specific data. 49 * 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. 57 */ 58 struct spi_slave { 59 unsigned int bus; 60 unsigned int cs; 61 u8 op_mode_rx; 62 unsigned int wordlen; 63 unsigned int max_write_size; 64 void *memory_map; 65 }; 66 67 /** 68 * Initialization, must be called once on start up. 69 * 70 * TODO: I don't think we really need this. 71 */ 72 void spi_init(void); 73 74 /** 75 * spi_do_alloc_slave - Allocate a new SPI slave (internal) 76 * 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. 79 * 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. 84 */ 85 void *spi_do_alloc_slave(int offset, int size, unsigned int bus, 86 unsigned int cs); 87 88 /** 89 * spi_alloc_slave - Allocate a new SPI slave 90 * 91 * Allocate and zero all fields in the spi slave, and set the bus/chip 92 * select. 93 * 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. 98 */ 99 #define spi_alloc_slave(_struct, bus, cs) \ 100 spi_do_alloc_slave(offsetof(_struct, slave), \ 101 sizeof(_struct), bus, cs) 102 103 /** 104 * spi_alloc_slave_base - Allocate a new SPI slave with no private data 105 * 106 * Allocate and zero all fields in the spi slave, and set the bus/chip 107 * select. 108 * 109 * @bus: Bus ID of the slave chip. 110 * @cs: Chip select ID of the slave chip on the specified bus. 111 */ 112 #define spi_alloc_slave_base(bus, cs) \ 113 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs) 114 115 /** 116 * Set up communications parameters for a SPI slave. 117 * 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 121 * initialized later. 122 * 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. 127 * 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. 130 */ 131 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 132 unsigned int max_hz, unsigned int mode); 133 134 /** 135 * Free any memory associated with a SPI slave. 136 * 137 * @slave: The SPI slave 138 */ 139 void spi_free_slave(struct spi_slave *slave); 140 141 /** 142 * Claim the bus and prepare it for communication with a given slave. 143 * 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. 149 * 150 * @slave: The SPI slave 151 * 152 * Returns: 0 if the bus was claimed successfully, or a negative value 153 * if it wasn't. 154 */ 155 int spi_claim_bus(struct spi_slave *slave); 156 157 /** 158 * Release the SPI bus 159 * 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 162 * appropriate. 163 * 164 * @slave: The SPI slave 165 */ 166 void spi_release_bus(struct spi_slave *slave); 167 168 /** 169 * Set the word length for SPI transactions 170 * 171 * Set the word length (number of bits per word) for SPI transactions. 172 * 173 * @slave: The SPI slave 174 * @wordlen: The number of bits in a word 175 * 176 * Returns: 0 on success, -1 on failure. 177 */ 178 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen); 179 180 /** 181 * SPI transfer 182 * 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. 185 * 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). 191 * 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. 199 * 200 * Returns: 0 on success, not 0 on failure 201 */ 202 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 203 void *din, unsigned long flags); 204 205 /** 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. 209 * 210 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 211 * otherwise. 212 */ 213 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 214 215 /** 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". 221 */ 222 void spi_cs_activate(struct spi_slave *slave); 223 224 /** 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". 230 */ 231 void spi_cs_deactivate(struct spi_slave *slave); 232 233 /** 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 238 */ 239 void spi_set_speed(struct spi_slave *slave, uint hz); 240 241 /** 242 * Write 8 bits, then read 8 bits. 243 * @slave: The SPI slave we're communicating with 244 * @byte: Byte to be written 245 * 246 * Returns: The value that was read, or a negative value on error. 247 * 248 * TODO: This function probably shouldn't be inlined. 249 */ 250 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 251 { 252 unsigned char dout[2]; 253 unsigned char din[2]; 254 int ret; 255 256 dout[0] = byte; 257 dout[1] = 0; 258 259 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 260 return ret < 0 ? ret : din[1]; 261 } 262 263 /** 264 * Set up a SPI slave for a particular device tree node 265 * 266 * This calls spi_setup_slave() with the correct bus number. Call 267 * spi_free_slave() to free it later. 268 * 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 273 */ 274 struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node, 275 int spi_node); 276 277 /** 278 * spi_base_setup_slave_fdt() - helper function to set up a SPI slace 279 * 280 * This decodes SPI properties from the slave node to determine the 281 * chip select and SPI parameters. 282 * 283 * @blob: Device tree blob 284 * @busnum: Bus number to use 285 * @node: Device tree node for the SPI bus 286 */ 287 struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum, 288 int node); 289 290 #endif /* _SPI_H_ */ 291