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 * Set up communications parameters for a SPI slave. 67 * 68 * This must be called once for each slave. Note that this function 69 * usually doesn't touch any actual hardware, it only initializes the 70 * contents of spi_slave so that the hardware can be easily 71 * initialized later. 72 * 73 * bus: Bus ID of the slave chip. 74 * cs: Chip select ID of the slave chip on the specified bus. 75 * max_hz: Maximum SCK rate in Hz. 76 * mode: Clock polarity, clock phase and other parameters. 77 * 78 * Returns: A spi_slave reference that can be used in subsequent SPI 79 * calls, or NULL if one or more of the parameters are not supported. 80 */ 81 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 82 unsigned int max_hz, unsigned int mode); 83 84 /*----------------------------------------------------------------------- 85 * Free any memory associated with a SPI slave. 86 * 87 * slave: The SPI slave 88 */ 89 void spi_free_slave(struct spi_slave *slave); 90 91 /*----------------------------------------------------------------------- 92 * Claim the bus and prepare it for communication with a given slave. 93 * 94 * This must be called before doing any transfers with a SPI slave. It 95 * will enable and initialize any SPI hardware as necessary, and make 96 * sure that the SCK line is in the correct idle state. It is not 97 * allowed to claim the same bus for several slaves without releasing 98 * the bus in between. 99 * 100 * slave: The SPI slave 101 * 102 * Returns: 0 if the bus was claimed successfully, or a negative value 103 * if it wasn't. 104 */ 105 int spi_claim_bus(struct spi_slave *slave); 106 107 /*----------------------------------------------------------------------- 108 * Release the SPI bus 109 * 110 * This must be called once for every call to spi_claim_bus() after 111 * all transfers have finished. It may disable any SPI hardware as 112 * appropriate. 113 * 114 * slave: The SPI slave 115 */ 116 void spi_release_bus(struct spi_slave *slave); 117 118 /*----------------------------------------------------------------------- 119 * SPI transfer 120 * 121 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks 122 * "bitlen" bits in the SPI MISO port. That's just the way SPI works. 123 * 124 * The source of the outgoing bits is the "dout" parameter and the 125 * destination of the input bits is the "din" parameter. Note that "dout" 126 * and "din" can point to the same memory location, in which case the 127 * input data overwrites the output data (since both are buffered by 128 * temporary variables, this is OK). 129 * 130 * spi_xfer() interface: 131 * slave: The SPI slave which will be sending/receiving the data. 132 * bitlen: How many bits to write and read. 133 * dout: Pointer to a string of bits to send out. The bits are 134 * held in a byte array and are sent MSB first. 135 * din: Pointer to a string of bits that will be filled in. 136 * flags: A bitwise combination of SPI_XFER_* flags. 137 * 138 * Returns: 0 on success, not 0 on failure 139 */ 140 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 141 void *din, unsigned long flags); 142 143 /*----------------------------------------------------------------------- 144 * Determine if a SPI chipselect is valid. 145 * This function is provided by the board if the low-level SPI driver 146 * needs it to determine if a given chipselect is actually valid. 147 * 148 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 149 * otherwise. 150 */ 151 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 152 153 /*----------------------------------------------------------------------- 154 * Activate a SPI chipselect. 155 * This function is provided by the board code when using a driver 156 * that can't control its chipselects automatically (e.g. 157 * common/soft_spi.c). When called, it should activate the chip select 158 * to the device identified by "slave". 159 */ 160 void spi_cs_activate(struct spi_slave *slave); 161 162 /*----------------------------------------------------------------------- 163 * Deactivate a SPI chipselect. 164 * This function is provided by the board code when using a driver 165 * that can't control its chipselects automatically (e.g. 166 * common/soft_spi.c). When called, it should deactivate the chip 167 * select to the device identified by "slave". 168 */ 169 void spi_cs_deactivate(struct spi_slave *slave); 170 171 /*----------------------------------------------------------------------- 172 * Set transfer speed. 173 * This sets a new speed to be applied for next spi_xfer(). 174 * slave: The SPI slave 175 * hz: The transfer speed 176 */ 177 void spi_set_speed(struct spi_slave *slave, uint hz); 178 179 /*----------------------------------------------------------------------- 180 * Write 8 bits, then read 8 bits. 181 * slave: The SPI slave we're communicating with 182 * byte: Byte to be written 183 * 184 * Returns: The value that was read, or a negative value on error. 185 * 186 * TODO: This function probably shouldn't be inlined. 187 */ 188 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 189 { 190 unsigned char dout[2]; 191 unsigned char din[2]; 192 int ret; 193 194 dout[0] = byte; 195 dout[1] = 0; 196 197 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 198 return ret < 0 ? ret : din[1]; 199 } 200 201 #endif /* _SPI_H_ */ 202