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 31 /* Header byte that marks the start of the message */ 32 #define SPI_PREAMBLE_END_BYTE 0xec 33 34 /** 35 * struct spi_slave: Representation of a SPI slave, 36 * i.e. what we're communicating with. 37 * 38 * Drivers are expected to extend this with controller-specific data. 39 * 40 * bus: ID of the bus that the slave is attached to. 41 * cs: ID of the chip select connected to the slave. 42 * max_write_size: If non-zero, the maximum number of bytes which can 43 * be written at once, excluding command bytes. 44 */ 45 struct spi_slave { 46 unsigned int bus; 47 unsigned int cs; 48 unsigned int max_write_size; 49 }; 50 51 /** 52 * Initialization, must be called once on start up. 53 * 54 * TODO: I don't think we really need this. 55 */ 56 void spi_init(void); 57 58 /** 59 * spi_do_alloc_slave - Allocate a new SPI slave (internal) 60 * 61 * Allocate and zero all fields in the spi slave, and set the bus/chip 62 * select. Use the helper macro spi_alloc_slave() to call this. 63 * 64 * @offset: Offset of struct spi_slave within slave structure. 65 * @size: Size of slave structure. 66 * @bus: Bus ID of the slave chip. 67 * @cs: Chip select ID of the slave chip on the specified bus. 68 */ 69 void *spi_do_alloc_slave(int offset, int size, unsigned int bus, 70 unsigned int cs); 71 72 /** 73 * spi_alloc_slave - Allocate a new SPI slave 74 * 75 * Allocate and zero all fields in the spi slave, and set the bus/chip 76 * select. 77 * 78 * @_struct: Name of structure to allocate (e.g. struct tegra_spi). 79 * This structure must contain a member 'struct spi_slave *slave'. 80 * @bus: Bus ID of the slave chip. 81 * @cs: Chip select ID of the slave chip on the specified bus. 82 */ 83 #define spi_alloc_slave(_struct, bus, cs) \ 84 spi_do_alloc_slave(offsetof(_struct, slave), \ 85 sizeof(_struct), bus, cs) 86 87 /** 88 * spi_alloc_slave_base - Allocate a new SPI slave with no private data 89 * 90 * Allocate and zero all fields in the spi slave, and set the bus/chip 91 * select. 92 * 93 * @bus: Bus ID of the slave chip. 94 * @cs: Chip select ID of the slave chip on the specified bus. 95 */ 96 #define spi_alloc_slave_base(bus, cs) \ 97 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs) 98 99 /** 100 * Set up communications parameters for a SPI slave. 101 * 102 * This must be called once for each slave. Note that this function 103 * usually doesn't touch any actual hardware, it only initializes the 104 * contents of spi_slave so that the hardware can be easily 105 * initialized later. 106 * 107 * @bus: Bus ID of the slave chip. 108 * @cs: Chip select ID of the slave chip on the specified bus. 109 * @max_hz: Maximum SCK rate in Hz. 110 * @mode: Clock polarity, clock phase and other parameters. 111 * 112 * Returns: A spi_slave reference that can be used in subsequent SPI 113 * calls, or NULL if one or more of the parameters are not supported. 114 */ 115 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 116 unsigned int max_hz, unsigned int mode); 117 118 /** 119 * Free any memory associated with a SPI slave. 120 * 121 * @slave: The SPI slave 122 */ 123 void spi_free_slave(struct spi_slave *slave); 124 125 /** 126 * Claim the bus and prepare it for communication with a given slave. 127 * 128 * This must be called before doing any transfers with a SPI slave. It 129 * will enable and initialize any SPI hardware as necessary, and make 130 * sure that the SCK line is in the correct idle state. It is not 131 * allowed to claim the same bus for several slaves without releasing 132 * the bus in between. 133 * 134 * @slave: The SPI slave 135 * 136 * Returns: 0 if the bus was claimed successfully, or a negative value 137 * if it wasn't. 138 */ 139 int spi_claim_bus(struct spi_slave *slave); 140 141 /** 142 * Release the SPI bus 143 * 144 * This must be called once for every call to spi_claim_bus() after 145 * all transfers have finished. It may disable any SPI hardware as 146 * appropriate. 147 * 148 * @slave: The SPI slave 149 */ 150 void spi_release_bus(struct spi_slave *slave); 151 152 /** 153 * SPI transfer 154 * 155 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks 156 * "bitlen" bits in the SPI MISO port. That's just the way SPI works. 157 * 158 * The source of the outgoing bits is the "dout" parameter and the 159 * destination of the input bits is the "din" parameter. Note that "dout" 160 * and "din" can point to the same memory location, in which case the 161 * input data overwrites the output data (since both are buffered by 162 * temporary variables, this is OK). 163 * 164 * spi_xfer() interface: 165 * @slave: The SPI slave which will be sending/receiving the data. 166 * @bitlen: How many bits to write and read. 167 * @dout: Pointer to a string of bits to send out. The bits are 168 * held in a byte array and are sent MSB first. 169 * @din: Pointer to a string of bits that will be filled in. 170 * @flags: A bitwise combination of SPI_XFER_* flags. 171 * 172 * Returns: 0 on success, not 0 on failure 173 */ 174 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 175 void *din, unsigned long flags); 176 177 /** 178 * Determine if a SPI chipselect is valid. 179 * This function is provided by the board if the low-level SPI driver 180 * needs it to determine if a given chipselect is actually valid. 181 * 182 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 183 * otherwise. 184 */ 185 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 186 187 /** 188 * Activate a SPI chipselect. 189 * This function is provided by the board code when using a driver 190 * that can't control its chipselects automatically (e.g. 191 * common/soft_spi.c). When called, it should activate the chip select 192 * to the device identified by "slave". 193 */ 194 void spi_cs_activate(struct spi_slave *slave); 195 196 /** 197 * Deactivate a SPI chipselect. 198 * This function is provided by the board code when using a driver 199 * that can't control its chipselects automatically (e.g. 200 * common/soft_spi.c). When called, it should deactivate the chip 201 * select to the device identified by "slave". 202 */ 203 void spi_cs_deactivate(struct spi_slave *slave); 204 205 /** 206 * Set transfer speed. 207 * This sets a new speed to be applied for next spi_xfer(). 208 * @slave: The SPI slave 209 * @hz: The transfer speed 210 */ 211 void spi_set_speed(struct spi_slave *slave, uint hz); 212 213 /** 214 * Write 8 bits, then read 8 bits. 215 * @slave: The SPI slave we're communicating with 216 * @byte: Byte to be written 217 * 218 * Returns: The value that was read, or a negative value on error. 219 * 220 * TODO: This function probably shouldn't be inlined. 221 */ 222 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 223 { 224 unsigned char dout[2]; 225 unsigned char din[2]; 226 int ret; 227 228 dout[0] = byte; 229 dout[1] = 0; 230 231 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 232 return ret < 0 ? ret : din[1]; 233 } 234 235 /** 236 * Set up a SPI slave for a particular device tree node 237 * 238 * This calls spi_setup_slave() with the correct bus number. Call 239 * spi_free_slave() to free it later. 240 * 241 * @param blob Device tree blob 242 * @param node SPI peripheral node to use 243 * @param cs Chip select to use 244 * @param max_hz Maximum SCK rate in Hz (0 for default) 245 * @param mode Clock polarity, clock phase and other parameters 246 * @return pointer to new spi_slave structure 247 */ 248 struct spi_slave *spi_setup_slave_fdt(const void *blob, int node, 249 unsigned int cs, unsigned int max_hz, unsigned int mode); 250 251 #endif /* _SPI_H_ */ 252