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/*
* (C) Copyright 2002
* Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
*
* Influenced by code from:
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* 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
*/
#include <common.h>
#include <spi.h>
#if defined(CONFIG_SOFT_SPI)
/*-----------------------------------------------------------------------
* Definitions
*/
#ifdef DEBUG_SPI
#define PRINTD(fmt,args...) printf (fmt ,##args)
#else
#define PRINTD(fmt,args...)
#endif
/*=====================================================================*/
/* Public Functions */
/*=====================================================================*/
/*-----------------------------------------------------------------------
* Initialization
*/
void spi_init (void)
{
#ifdef SPI_INIT
volatile immap_t *immr = (immap_t *)CFG_IMMR;
SPI_INIT;
#endif
}
/*-----------------------------------------------------------------------
* 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.
*/
int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din)
{
#ifdef CFG_IMMR
volatile immap_t *immr = (immap_t *)CFG_IMMR;
#endif
uchar tmpdin = 0;
uchar tmpdout = 0;
int j;
PRINTD("spi_xfer: chipsel %08X dout %08X din %08X bitlen %d\n",
(int)chipsel, *(uint *)dout, *(uint *)din, bitlen);
if(chipsel != NULL) {
(*chipsel)(1); /* select the target chip */
}
for(j = 0; j < bitlen; j++) {
/*
* Check if it is time to work on a new byte.
*/
if((j % 8) == 0) {
tmpdout = *dout++;
if(j != 0) {
*din++ = tmpdin;
}
tmpdin = 0;
}
SPI_SCL(0);
SPI_SDA(tmpdout & 0x80);
SPI_DELAY;
SPI_SCL(1);
SPI_DELAY;
tmpdin <<= 1;
tmpdin |= SPI_READ;
tmpdout <<= 1;
}
/*
* If the number of bits isn't a multiple of 8, shift the last
* bits over to left-justify them. Then store the last byte
* read in.
*/
if((bitlen % 8) != 0)
tmpdin <<= 8 - (bitlen % 8);
*din++ = tmpdin;
SPI_SCL(0); /* SPI wants the clock left low for idle */
if(chipsel != NULL) {
(*chipsel)(0); /* deselect the target chip */
}
return(0);
}
#endif /* CONFIG_SOFT_SPI */
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