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/*
* i2c Support for Atmel's AT91RM9200 Two-Wire Interface
*
* (c) Rick Bronson
*
* Borrowed heavily from original work by:
* Copyright (c) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
*
* Modified to work with u-boot by (C) 2004 Gary Jennejohn garyj@denx.de
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <common.h>
#ifdef CONFIG_HARD_I2C
#include <i2c.h>
#include <asm/io.h>
#include <asm/arch/hardware.h>
#include <at91rm9200_i2c.h>
/* define DEBUG */
/*
* Poll the i2c status register until the specified bit is set.
* Returns 0 if timed out (100 msec)
*/
static short at91_poll_status(AT91PS_TWI twi, unsigned long bit) {
int loop_cntr = 10000;
do {
udelay(10);
} while (!(twi->TWI_SR & bit) && (--loop_cntr > 0));
return (loop_cntr > 0);
}
/*
* Generic i2c master transfer entrypoint
*
* rw == 1 means that this is a read
*/
static int
at91_xfer(unsigned char chip, unsigned int addr, int alen,
unsigned char *buffer, int len, int rw)
{
AT91PS_TWI twi = (AT91PS_TWI) AT91_TWI_BASE;
int length;
unsigned char *buf;
/* Set the TWI Master Mode Register */
twi->TWI_MMR = (chip << 16) | (alen << 8)
| ((rw == 1) ? AT91C_TWI_MREAD : 0);
/* Set TWI Internal Address Register with first messages data field */
/* only one address byte is supported */
if (alen > 0)
twi->TWI_IADR = addr & 0xff;
length = len;
buf = buffer;
if (length && buf) { /* sanity check */
if (rw) {
twi->TWI_CR = AT91C_TWI_START;
while (length--) {
if (!length)
twi->TWI_CR = AT91C_TWI_STOP;
/* Wait until transfer is finished */
if (!at91_poll_status(twi, AT91C_TWI_RXRDY)) {
debug ("at91_i2c: timeout 1\n");
return 1;
}
*buf++ = twi->TWI_RHR;
}
if (!at91_poll_status(twi, AT91C_TWI_TXCOMP)) {
debug ("at91_i2c: timeout 2\n");
return 1;
}
} else {
twi->TWI_CR = AT91C_TWI_START;
while (length--) {
twi->TWI_THR = *buf++;
if (!length)
twi->TWI_CR = AT91C_TWI_STOP;
if (!at91_poll_status(twi, AT91C_TWI_TXRDY)) {
debug ("at91_i2c: timeout 3\n");
return 1;
}
}
/* Wait until transfer is finished */
if (!at91_poll_status(twi, AT91C_TWI_TXCOMP)) {
debug ("at91_i2c: timeout 4\n");
return 1;
}
}
}
return 0;
}
int
i2c_probe(unsigned char chip)
{
char buffer[1];
return at91_xfer(chip, 0, 0, buffer, 1, 1);
}
int
i2c_read (unsigned char chip, unsigned int addr, int alen,
unsigned char *buffer, int len)
{
#ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
/* we only allow one address byte */
if (alen > 1)
return 1;
/* XXX assume an ATMEL AT24C16 */
if (alen == 1) {
#if 0 /* EEPROM code already sets this correctly */
chip |= (addr >> 8) & 0xff;
#endif
addr = addr & 0xff;
}
#endif
return at91_xfer(chip, addr, alen, buffer, len, 1);
}
int
i2c_write(unsigned char chip, unsigned int addr, int alen,
unsigned char *buffer, int len)
{
int i;
unsigned char *buf;
#ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
/* we only allow one address byte */
if (alen > 1)
return 1;
/* XXX assume an ATMEL AT24C16 */
if (alen == 1) {
buf = buffer;
/* do single byte writes */
for (i = 0; i < len; i++) {
#if 0 /* EEPROM code already sets this correctly */
chip |= (addr >> 8) & 0xff;
#endif
addr = addr & 0xff;
if (at91_xfer(chip, addr, alen, buf++, 1, 0))
return 1;
addr++;
}
return 0;
}
#endif
return at91_xfer(chip, addr, alen, buffer, len, 0);
}
/*
* Main initialization routine
*/
void
i2c_init(int speed, int slaveaddr)
{
AT91PS_TWI twi = (AT91PS_TWI) AT91_TWI_BASE;
*AT91C_PIOA_PDR = AT91C_PA25_TWD | AT91C_PA26_TWCK;
*AT91C_PIOA_ASR = AT91C_PA25_TWD | AT91C_PA26_TWCK;
*AT91C_PIOA_MDER = AT91C_PA25_TWD | AT91C_PA26_TWCK;
*AT91C_PMC_PCER = 1 << AT91C_ID_TWI; /* enable peripheral clock */
twi->TWI_IDR = 0x3ff; /* Disable all interrupts */
twi->TWI_CR = AT91C_TWI_SWRST; /* Reset peripheral */
twi->TWI_CR = AT91C_TWI_MSEN | AT91C_TWI_SVDIS; /* Set Master mode */
/* Here, CKDIV = 1 and CHDIV=CLDIV ==> CLDIV = CHDIV = 1/4*((Fmclk/FTWI) -6) */
twi->TWI_CWGR = AT91C_TWI_CKDIV1 | AT91C_TWI_CLDIV3 | (AT91C_TWI_CLDIV3 << 8);
debug ("Found AT91 i2c\n");
return;
}
#endif /* CONFIG_HARD_I2C */
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