1 /* 2 * (C) Copyright 2001 3 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com. 4 * 5 * See file CREDITS for list of people who contributed to this 6 * project. 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License as 10 * published by the Free Software Foundation; either version 2 of 11 * the License, or (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 21 * MA 02111-1307 USA 22 */ 23 24 #ifndef _SPI_H_ 25 #define _SPI_H_ 26 27 /* Controller-specific definitions: */ 28 29 /* SPI mode flags */ 30 #define SPI_CPHA 0x01 /* clock phase */ 31 #define SPI_CPOL 0x02 /* clock polarity */ 32 #define SPI_MODE_0 (0|0) /* (original MicroWire) */ 33 #define SPI_MODE_1 (0|SPI_CPHA) 34 #define SPI_MODE_2 (SPI_CPOL|0) 35 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA) 36 #define SPI_CS_HIGH 0x04 /* CS active high */ 37 #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */ 38 #define SPI_3WIRE 0x10 /* SI/SO signals shared */ 39 #define SPI_LOOP 0x20 /* loopback mode */ 40 #define SPI_SLAVE 0x40 /* slave mode */ 41 #define SPI_PREAMBLE 0x80 /* Skip preamble bytes */ 42 43 /* SPI transfer flags */ 44 #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */ 45 #define SPI_XFER_END 0x02 /* Deassert CS after transfer */ 46 47 /* Header byte that marks the start of the message */ 48 #define SPI_PREAMBLE_END_BYTE 0xec 49 50 /*----------------------------------------------------------------------- 51 * Representation of a SPI slave, i.e. what we're communicating with. 52 * 53 * Drivers are expected to extend this with controller-specific data. 54 * 55 * bus: ID of the bus that the slave is attached to. 56 * cs: ID of the chip select connected to the slave. 57 * max_write_size: If non-zero, the maximum number of bytes which can 58 * be written at once, excluding command bytes. 59 */ 60 struct spi_slave { 61 unsigned int bus; 62 unsigned int cs; 63 unsigned int max_write_size; 64 }; 65 66 /*----------------------------------------------------------------------- 67 * Initialization, must be called once on start up. 68 * 69 * TODO: I don't think we really need this. 70 */ 71 void spi_init(void); 72 73 /** 74 * spi_do_alloc_slave - Allocate a new SPI slave (internal) 75 * 76 * Allocate and zero all fields in the spi slave, and set the bus/chip 77 * select. Use the helper macro spi_alloc_slave() to call this. 78 * 79 * @offset: Offset of struct spi_slave within slave structure 80 * @size: Size of slave structure 81 * @bus: Bus ID of the slave chip. 82 * @cs: Chip select ID of the slave chip on the specified bus. 83 */ 84 void *spi_do_alloc_slave(int offset, int size, unsigned int bus, 85 unsigned int cs); 86 87 /** 88 * spi_alloc_slave - Allocate a new SPI slave 89 * 90 * Allocate and zero all fields in the spi slave, and set the bus/chip 91 * select. 92 * 93 * @_struct: Name of structure to allocate (e.g. struct tegra_spi). This 94 * structure must contain a member 'struct spi_slave *slave'. 95 * @bus: Bus ID of the slave chip. 96 * @cs: Chip select ID of the slave chip on the specified bus. 97 */ 98 #define spi_alloc_slave(_struct, bus, cs) \ 99 spi_do_alloc_slave(offsetof(_struct, slave), \ 100 sizeof(_struct), bus, cs) 101 102 /** 103 * spi_alloc_slave_base - Allocate a new SPI slave with no private data 104 * 105 * Allocate and zero all fields in the spi slave, and set the bus/chip 106 * select. 107 * 108 * @bus: Bus ID of the slave chip. 109 * @cs: Chip select ID of the slave chip on the specified bus. 110 */ 111 #define spi_alloc_slave_base(bus, cs) \ 112 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs) 113 114 /*----------------------------------------------------------------------- 115 * Set up communications parameters for a SPI slave. 116 * 117 * This must be called once for each slave. Note that this function 118 * usually doesn't touch any actual hardware, it only initializes the 119 * contents of spi_slave so that the hardware can be easily 120 * initialized later. 121 * 122 * bus: Bus ID of the slave chip. 123 * cs: Chip select ID of the slave chip on the specified bus. 124 * max_hz: Maximum SCK rate in Hz. 125 * mode: Clock polarity, clock phase and other parameters. 126 * 127 * Returns: A spi_slave reference that can be used in subsequent SPI 128 * calls, or NULL if one or more of the parameters are not supported. 129 */ 130 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 131 unsigned int max_hz, unsigned int mode); 132 133 /*----------------------------------------------------------------------- 134 * Free any memory associated with a SPI slave. 135 * 136 * slave: The SPI slave 137 */ 138 void spi_free_slave(struct spi_slave *slave); 139 140 /*----------------------------------------------------------------------- 141 * Claim the bus and prepare it for communication with a given slave. 142 * 143 * This must be called before doing any transfers with a SPI slave. It 144 * will enable and initialize any SPI hardware as necessary, and make 145 * sure that the SCK line is in the correct idle state. It is not 146 * allowed to claim the same bus for several slaves without releasing 147 * the bus in between. 148 * 149 * slave: The SPI slave 150 * 151 * Returns: 0 if the bus was claimed successfully, or a negative value 152 * if it wasn't. 153 */ 154 int spi_claim_bus(struct spi_slave *slave); 155 156 /*----------------------------------------------------------------------- 157 * Release the SPI bus 158 * 159 * This must be called once for every call to spi_claim_bus() after 160 * all transfers have finished. It may disable any SPI hardware as 161 * appropriate. 162 * 163 * slave: The SPI slave 164 */ 165 void spi_release_bus(struct spi_slave *slave); 166 167 /*----------------------------------------------------------------------- 168 * SPI transfer 169 * 170 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks 171 * "bitlen" bits in the SPI MISO port. That's just the way SPI works. 172 * 173 * The source of the outgoing bits is the "dout" parameter and the 174 * destination of the input bits is the "din" parameter. Note that "dout" 175 * and "din" can point to the same memory location, in which case the 176 * input data overwrites the output data (since both are buffered by 177 * temporary variables, this is OK). 178 * 179 * spi_xfer() interface: 180 * slave: The SPI slave which will be sending/receiving the data. 181 * bitlen: How many bits to write and read. 182 * dout: Pointer to a string of bits to send out. The bits are 183 * held in a byte array and are sent MSB first. 184 * din: Pointer to a string of bits that will be filled in. 185 * flags: A bitwise combination of SPI_XFER_* flags. 186 * 187 * Returns: 0 on success, not 0 on failure 188 */ 189 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 190 void *din, unsigned long flags); 191 192 /*----------------------------------------------------------------------- 193 * Determine if a SPI chipselect is valid. 194 * This function is provided by the board if the low-level SPI driver 195 * needs it to determine if a given chipselect is actually valid. 196 * 197 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 198 * otherwise. 199 */ 200 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 201 202 /*----------------------------------------------------------------------- 203 * Activate a SPI chipselect. 204 * This function is provided by the board code when using a driver 205 * that can't control its chipselects automatically (e.g. 206 * common/soft_spi.c). When called, it should activate the chip select 207 * to the device identified by "slave". 208 */ 209 void spi_cs_activate(struct spi_slave *slave); 210 211 /*----------------------------------------------------------------------- 212 * Deactivate a SPI chipselect. 213 * This function is provided by the board code when using a driver 214 * that can't control its chipselects automatically (e.g. 215 * common/soft_spi.c). When called, it should deactivate the chip 216 * select to the device identified by "slave". 217 */ 218 void spi_cs_deactivate(struct spi_slave *slave); 219 220 /*----------------------------------------------------------------------- 221 * Set transfer speed. 222 * This sets a new speed to be applied for next spi_xfer(). 223 * slave: The SPI slave 224 * hz: The transfer speed 225 */ 226 void spi_set_speed(struct spi_slave *slave, uint hz); 227 228 /*----------------------------------------------------------------------- 229 * Write 8 bits, then read 8 bits. 230 * slave: The SPI slave we're communicating with 231 * byte: Byte to be written 232 * 233 * Returns: The value that was read, or a negative value on error. 234 * 235 * TODO: This function probably shouldn't be inlined. 236 */ 237 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 238 { 239 unsigned char dout[2]; 240 unsigned char din[2]; 241 int ret; 242 243 dout[0] = byte; 244 dout[1] = 0; 245 246 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 247 return ret < 0 ? ret : din[1]; 248 } 249 250 /** 251 * Set up a SPI slave for a particular device tree node 252 * 253 * This calls spi_setup_slave() with the correct bus number. Call 254 * spi_free_slave() to free it later. 255 * 256 * @param blob Device tree blob 257 * @param node SPI peripheral node to use 258 * @param cs Chip select to use 259 * @param max_hz Maximum SCK rate in Hz (0 for default) 260 * @param mode Clock polarity, clock phase and other parameters 261 * @return pointer to new spi_slave structure 262 */ 263 struct spi_slave *spi_setup_slave_fdt(const void *blob, int node, 264 unsigned int cs, unsigned int max_hz, unsigned int mode); 265 266 #endif /* _SPI_H_ */ 267