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 /* CONFIG_HARD_SPI triggers SPI bus initialization in PowerPC */ 30 #ifdef CONFIG_MPC8XXX_SPI 31 # ifndef CONFIG_HARD_SPI 32 # define CONFIG_HARD_SPI 33 # endif 34 #endif 35 36 /* SPI mode flags */ 37 #define SPI_CPHA 0x01 /* clock phase */ 38 #define SPI_CPOL 0x02 /* clock polarity */ 39 #define SPI_MODE_0 (0|0) /* (original MicroWire) */ 40 #define SPI_MODE_1 (0|SPI_CPHA) 41 #define SPI_MODE_2 (SPI_CPOL|0) 42 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA) 43 #define SPI_CS_HIGH 0x04 /* CS active high */ 44 #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */ 45 #define SPI_3WIRE 0x10 /* SI/SO signals shared */ 46 #define SPI_LOOP 0x20 /* loopback mode */ 47 48 /* SPI transfer flags */ 49 #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */ 50 #define SPI_XFER_END 0x02 /* Deassert CS after transfer */ 51 52 /*----------------------------------------------------------------------- 53 * Representation of a SPI slave, i.e. what we're communicating with. 54 * 55 * Drivers are expected to extend this with controller-specific data. 56 * 57 * bus: ID of the bus that the slave is attached to. 58 * cs: ID of the chip select connected to the slave. 59 */ 60 struct spi_slave { 61 unsigned int bus; 62 unsigned int cs; 63 }; 64 65 /*----------------------------------------------------------------------- 66 * Initialization, must be called once on start up. 67 * 68 * TODO: I don't think we really need this. 69 */ 70 void spi_init(void); 71 72 /*----------------------------------------------------------------------- 73 * Set up communications parameters for a SPI slave. 74 * 75 * This must be called once for each slave. Note that this function 76 * usually doesn't touch any actual hardware, it only initializes the 77 * contents of spi_slave so that the hardware can be easily 78 * initialized later. 79 * 80 * bus: Bus ID of the slave chip. 81 * cs: Chip select ID of the slave chip on the specified bus. 82 * max_hz: Maximum SCK rate in Hz. 83 * mode: Clock polarity, clock phase and other parameters. 84 * 85 * Returns: A spi_slave reference that can be used in subsequent SPI 86 * calls, or NULL if one or more of the parameters are not supported. 87 */ 88 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 89 unsigned int max_hz, unsigned int mode); 90 91 /*----------------------------------------------------------------------- 92 * Free any memory associated with a SPI slave. 93 * 94 * slave: The SPI slave 95 */ 96 void spi_free_slave(struct spi_slave *slave); 97 98 /*----------------------------------------------------------------------- 99 * Claim the bus and prepare it for communication with a given slave. 100 * 101 * This must be called before doing any transfers with a SPI slave. It 102 * will enable and initialize any SPI hardware as necessary, and make 103 * sure that the SCK line is in the correct idle state. It is not 104 * allowed to claim the same bus for several slaves without releasing 105 * the bus in between. 106 * 107 * slave: The SPI slave 108 * 109 * Returns: 0 if the bus was claimed successfully, or a negative value 110 * if it wasn't. 111 */ 112 int spi_claim_bus(struct spi_slave *slave); 113 114 /*----------------------------------------------------------------------- 115 * Release the SPI bus 116 * 117 * This must be called once for every call to spi_claim_bus() after 118 * all transfers have finished. It may disable any SPI hardware as 119 * appropriate. 120 * 121 * slave: The SPI slave 122 */ 123 void spi_release_bus(struct spi_slave *slave); 124 125 /*----------------------------------------------------------------------- 126 * SPI transfer 127 * 128 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks 129 * "bitlen" bits in the SPI MISO port. That's just the way SPI works. 130 * 131 * The source of the outgoing bits is the "dout" parameter and the 132 * destination of the input bits is the "din" parameter. Note that "dout" 133 * and "din" can point to the same memory location, in which case the 134 * input data overwrites the output data (since both are buffered by 135 * temporary variables, this is OK). 136 * 137 * spi_xfer() interface: 138 * slave: The SPI slave which will be sending/receiving the data. 139 * bitlen: How many bits to write and read. 140 * dout: Pointer to a string of bits to send out. The bits are 141 * held in a byte array and are sent MSB first. 142 * din: Pointer to a string of bits that will be filled in. 143 * flags: A bitwise combination of SPI_XFER_* flags. 144 * 145 * Returns: 0 on success, not 0 on failure 146 */ 147 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, 148 void *din, unsigned long flags); 149 150 /*----------------------------------------------------------------------- 151 * Determine if a SPI chipselect is valid. 152 * This function is provided by the board if the low-level SPI driver 153 * needs it to determine if a given chipselect is actually valid. 154 * 155 * Returns: 1 if bus:cs identifies a valid chip on this board, 0 156 * otherwise. 157 */ 158 int spi_cs_is_valid(unsigned int bus, unsigned int cs); 159 160 /*----------------------------------------------------------------------- 161 * Activate a SPI chipselect. 162 * This function is provided by the board code when using a driver 163 * that can't control its chipselects automatically (e.g. 164 * common/soft_spi.c). When called, it should activate the chip select 165 * to the device identified by "slave". 166 */ 167 void spi_cs_activate(struct spi_slave *slave); 168 169 /*----------------------------------------------------------------------- 170 * Deactivate a SPI chipselect. 171 * This function is provided by the board code when using a driver 172 * that can't control its chipselects automatically (e.g. 173 * common/soft_spi.c). When called, it should deactivate the chip 174 * select to the device identified by "slave". 175 */ 176 void spi_cs_deactivate(struct spi_slave *slave); 177 178 /*----------------------------------------------------------------------- 179 * Write 8 bits, then read 8 bits. 180 * slave: The SPI slave we're communicating with 181 * byte: Byte to be written 182 * 183 * Returns: The value that was read, or a negative value on error. 184 * 185 * TODO: This function probably shouldn't be inlined. 186 */ 187 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) 188 { 189 unsigned char dout[2]; 190 unsigned char din[2]; 191 int ret; 192 193 dout[0] = byte; 194 dout[1] = 0; 195 196 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); 197 return ret < 0 ? ret : din[1]; 198 } 199 200 #endif /* _SPI_H_ */ 201