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