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| -rw-r--r-- | include/spi.h | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/include/spi.h b/include/spi.h new file mode 100644 index 0000000000..03dc5bc036 --- /dev/null +++ b/include/spi.h @@ -0,0 +1,73 @@ +/* + * (C) Copyright 2001 + * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com. + * + * See file CREDITS for list of people who contributed to this + * project. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +#ifndef _SPI_H_ +#define _SPI_H_ + +/* + * The function call pointer type used to drive the chip select. + */ +typedef void (*spi_chipsel_type)(int cs); + + +/*----------------------------------------------------------------------- + * Initialization, must be called once on start up. + */ +void spi_init(void); + + +/*----------------------------------------------------------------------- + * SPI transfer + * + * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks + * "bitlen" bits in the SPI MISO port. That's just the way SPI works. + * + * The source of the outgoing bits is the "dout" parameter and the + * destination of the input bits is the "din" parameter. Note that "dout" + * and "din" can point to the same memory location, in which case the + * input data overwrites the output data (since both are buffered by + * temporary variables, this is OK). + * + * If the chipsel() function is not NULL, it is called with a parameter + * of '1' (chip select active) at the start of the transfer and again with + * a parameter of '0' at the end of the transfer. + * + * If the chipsel() function _is_ NULL, it the responsibility of the + * caller to make the appropriate chip select active before calling + * spi_xfer() and making it inactive after spi_xfer() returns. + * + * spi_xfer() interface: + * chipsel: Routine to call to set/clear the chip select: + * if chipsel is NULL, it is not used. + * if(cs), make the chip select active (typically '0'). + * if(!cs), make the chip select inactive (typically '1'). + * dout: Pointer to a string of bits to send out. The bits are + * held in a byte array and are sent MSB first. + * din: Pointer to a string of bits that will be filled in. + * bitlen: How many bits to write and read. + * + * Returns: 0 on success, not 0 on failure + */ +int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din); + +#endif /* _SPI_H_ */ |