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