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 41 /* SPI transfer flags */ 42 #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */ 43 #define SPI_XFER_END 0x02 /* Deassert CS after transfer */ 44 45 /*----------------------------------------------------------------------- 46 * Representation of a SPI slave, i.e. what we're communicating with. 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 * max_write_size: If non-zero, the maximum number of bytes which can 53 * be written at once, excluding command bytes. 54 */ 55 struct spi_slave { 56 unsigned int bus; 57 unsigned int cs; 58 unsigned int max_write_size; 59 }; 60 61 /*----------------------------------------------------------------------- 62 * Initialization, must be called once on start up. 63 * 64 * TODO: I don't think we really need this. 65 */ 66 void spi_init(void); 67 68 /** 69 * spi_do_alloc_slave - Allocate a new SPI slave (internal) 70 * 71 * Allocate and zero all fields in the spi slave, and set the bus/chip 72 * select. Use the helper macro spi_alloc_slave() to call this. 73 * 74 * @offset: Offset of struct spi_slave within slave structure 75 * @size: Size of slave structure 76 * @bus: Bus ID of the slave chip. 77 * @cs: Chip select ID of the slave chip on the specified bus. 78 */ 79 void *spi_do_alloc_slave(int offset, int size, unsigned int bus, 80 unsigned int cs); 81 82 /** 83 * spi_alloc_slave - Allocate a new SPI slave 84 * 85 * Allocate and zero all fields in the spi slave, and set the bus/chip 86 * select. 87 * 88 * @_struct: Name of structure to allocate (e.g. struct tegra_spi). This 89 * structure must contain a member 'struct spi_slave *slave'. 90 * @bus: Bus ID of the slave chip. 91 * @cs: Chip select ID of the slave chip on the specified bus. 92 */ 93 #define spi_alloc_slave(_struct, bus, cs) \ 94 spi_do_alloc_slave(offsetof(_struct, slave), \ 95 sizeof(_struct), bus, cs) 96 97 /** 98 * spi_alloc_slave_base - Allocate a new SPI slave with no private data 99 * 100 * Allocate and zero all fields in the spi slave, and set the bus/chip 101 * select. 102 * 103 * @bus: Bus ID of the slave chip. 104 * @cs: Chip select ID of the slave chip on the specified bus. 105 */ 106 #define spi_alloc_slave_base(bus, cs) \ 107 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs) 108 109 /*----------------------------------------------------------------------- 110 * Set up communications parameters for a SPI slave. 111 * 112 * This must be called once for each slave. Note that this function 113 * usually doesn't touch any actual hardware, it only initializes the 114 * contents of spi_slave so that the hardware can be easily 115 * initialized later. 116 * 117 * bus: Bus ID of the slave chip. 118 * cs: Chip select ID of the slave chip on the specified bus. 119 * max_hz: Maximum SCK rate in Hz. 120 * mode: Clock polarity, clock phase and other parameters. 121 * 122 * Returns: A spi_slave reference that can be used in subsequent SPI 123 * calls, or NULL if one or more of the parameters are not supported. 124 */ 125 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 126 unsigned int max_hz, unsigned int mode); 127 128 /*----------------------------------------------------------------------- 129 * Free any memory associated with a SPI slave. 130 * 131 * slave: The SPI slave 132 */ 133 void spi_free_slave(struct spi_slave *slave); 134 135 /*----------------------------------------------------------------------- 136 * Claim the bus and prepare it for communication with a given slave. 137 * 138 * This must be called before doing any transfers with a SPI slave. It 139 * will enable and initialize any SPI hardware as necessary, and make 140 * sure that the SCK line is in the correct idle state. It is not 141 * allowed to claim the same bus for several slaves without releasing 142 * the bus in between. 143 * 144 * slave: The SPI slave 145 * 146 * Returns: 0 if the bus was claimed successfully, or a negative value 147 * if it wasn't. 148 */ 149 int spi_claim_bus(struct spi_slave *slave); 150 151 /*----------------------------------------------------------------------- 152 * Release the SPI bus 153 * 154 * This must be called once for every call to spi_claim_bus() after 155 * all transfers have finished. It may disable any SPI hardware as 156 * appropriate. 157 * 158 * slave: The SPI slave 159 */ 160 void spi_release_bus(struct spi_slave *slave); 161 162 /*----------------------------------------------------------------------- 163 * SPI transfer 164 * 165 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks 166 * "bitlen" bits in the SPI MISO port. That's just the way SPI works. 167 * 168 * The source of the outgoing bits is the "dout" parameter and the 169 * destination of the input bits is the "din" parameter. Note that "dout" 170 * and "din" can point to the same memory location, in which case the 171 * input data overwrites the output data (since both are buffered by 172 * temporary variables, this is OK). 173 * 174 * spi_xfer() interface: 175 * slave: The SPI slave which will be sending/receiving the data. 176 * bitlen: How many bits to write and read. 177 * dout: Pointer to a string of bits to send out. The bits are 178 * held in a byte array and are sent MSB first. 179 * din: Pointer to a string of bits that will be filled in. 180 * flags: A bitwise combination of SPI_XFER_* flags. 181 * 182 * Returns: 0 on success, not 0 on failure 183 */ 184 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 185 void *din, unsigned long flags); 186 187 /*----------------------------------------------------------------------- 188 * Determine if a SPI chipselect is valid. 189 * This function is provided by the board if the low-level SPI driver 190 * needs it to determine if a given chipselect is actually valid. 191 * 192 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 193 * otherwise. 194 */ 195 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 196 197 /*----------------------------------------------------------------------- 198 * Activate a SPI chipselect. 199 * This function is provided by the board code when using a driver 200 * that can't control its chipselects automatically (e.g. 201 * common/soft_spi.c). When called, it should activate the chip select 202 * to the device identified by "slave". 203 */ 204 void spi_cs_activate(struct spi_slave *slave); 205 206 /*----------------------------------------------------------------------- 207 * Deactivate a SPI chipselect. 208 * This function is provided by the board code when using a driver 209 * that can't control its chipselects automatically (e.g. 210 * common/soft_spi.c). When called, it should deactivate the chip 211 * select to the device identified by "slave". 212 */ 213 void spi_cs_deactivate(struct spi_slave *slave); 214 215 /*----------------------------------------------------------------------- 216 * Set transfer speed. 217 * This sets a new speed to be applied for next spi_xfer(). 218 * slave: The SPI slave 219 * hz: The transfer speed 220 */ 221 void spi_set_speed(struct spi_slave *slave, uint hz); 222 223 /*----------------------------------------------------------------------- 224 * Write 8 bits, then read 8 bits. 225 * slave: The SPI slave we're communicating with 226 * byte: Byte to be written 227 * 228 * Returns: The value that was read, or a negative value on error. 229 * 230 * TODO: This function probably shouldn't be inlined. 231 */ 232 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 233 { 234 unsigned char dout[2]; 235 unsigned char din[2]; 236 int ret; 237 238 dout[0] = byte; 239 dout[1] = 0; 240 241 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 242 return ret < 0 ? ret : din[1]; 243 } 244 245 #endif /* _SPI_H_ */ 246