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 /* SPI mode flags */ 28 #define SPI_CPHA 0x01 /* clock phase */ 29 #define SPI_CPOL 0x02 /* clock polarity */ 30 #define SPI_MODE_0 (0|0) /* (original MicroWire) */ 31 #define SPI_MODE_1 (0|SPI_CPHA) 32 #define SPI_MODE_2 (SPI_CPOL|0) 33 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA) 34 #define SPI_CS_HIGH 0x04 /* chipselect active high? */ 35 #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */ 36 #define SPI_3WIRE 0x10 /* SI/SO signals shared */ 37 #define SPI_LOOP 0x20 /* loopback mode */ 38 39 /* 40 * The function call pointer type used to drive the chip select. 41 */ 42 typedef void (*spi_chipsel_type)(int cs); 43 44 45 /*----------------------------------------------------------------------- 46 * Initialization, must be called once on start up. 47 */ 48 void spi_init(void); 49 50 51 /*----------------------------------------------------------------------- 52 * SPI transfer 53 * 54 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks 55 * "bitlen" bits in the SPI MISO port. That's just the way SPI works. 56 * 57 * The source of the outgoing bits is the "dout" parameter and the 58 * destination of the input bits is the "din" parameter. Note that "dout" 59 * and "din" can point to the same memory location, in which case the 60 * input data overwrites the output data (since both are buffered by 61 * temporary variables, this is OK). 62 * 63 * If the chipsel() function is not NULL, it is called with a parameter 64 * of '1' (chip select active) at the start of the transfer and again with 65 * a parameter of '0' at the end of the transfer. 66 * 67 * If the chipsel() function _is_ NULL, it the responsibility of the 68 * caller to make the appropriate chip select active before calling 69 * spi_xfer() and making it inactive after spi_xfer() returns. 70 * 71 * spi_xfer() interface: 72 * chipsel: Routine to call to set/clear the chip select: 73 * if chipsel is NULL, it is not used. 74 * if(cs), make the chip select active (typically '0'). 75 * if(!cs), make the chip select inactive (typically '1'). 76 * dout: Pointer to a string of bits to send out. The bits are 77 * held in a byte array and are sent MSB first. 78 * din: Pointer to a string of bits that will be filled in. 79 * bitlen: How many bits to write and read. 80 * 81 * Returns: 0 on success, not 0 on failure 82 */ 83 int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din); 84 85 int spi_select(unsigned int bus, unsigned int dev, unsigned long mode); 86 87 #endif /* _SPI_H_ */ 88