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