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u-boot/common/soft_i2c.c

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/*
* (C) Copyright 2001, 2002
* 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
*
* This has been changed substantially by Gerald Van Baren, Custom IDEAS,
* vanbaren@cideas.com. It was heavily influenced by LiMon, written by
* Neil Russell.
*/
#include <common.h>
#ifdef CONFIG_MPC8260 /* only valid for MPC8260 */
#include <ioports.h>
#endif
#ifdef CONFIG_AT91RM9200DK /* need this for the at91rm9200dk */
#include <asm/io.h>
#include <asm/arch/hardware.h>
#endif
#include <i2c.h>
#if defined(CONFIG_SOFT_I2C)
/* #define DEBUG_I2C */
#ifdef DEBUG_I2C
DECLARE_GLOBAL_DATA_PTR;
#endif
/*-----------------------------------------------------------------------
* Definitions
*/
#define RETRIES 0
#define I2C_ACK 0 /* PD_SDA level to ack a byte */
#define I2C_NOACK 1 /* PD_SDA level to noack a byte */
#ifdef DEBUG_I2C
#define PRINTD(fmt,args...) do { \
if (gd->have_console) \
printf (fmt ,##args); \
} while (0)
#else
#define PRINTD(fmt,args...)
#endif
/*-----------------------------------------------------------------------
* Local functions
*/
static void send_reset (void);
static void send_start (void);
static void send_stop (void);
static void send_ack (int);
static int write_byte (uchar byte);
static uchar read_byte (int);
/*-----------------------------------------------------------------------
* Send a reset sequence consisting of 9 clocks with the data signal high
* to clock any confused device back into an idle state. Also send a
* <stop> at the end of the sequence for belts & suspenders.
*/
static void send_reset(void)
{
#ifdef CONFIG_MPC8260
volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
#endif
#ifdef CONFIG_8xx
volatile immap_t *immr = (immap_t *)CFG_IMMR;
#endif
int j;
I2C_SCL(1);
I2C_SDA(1);
#ifdef I2C_INIT
I2C_INIT;
#endif
I2C_TRISTATE;
for(j = 0; j < 9; j++) {
I2C_SCL(0);
I2C_DELAY;
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_DELAY;
}
send_stop();
I2C_TRISTATE;
}
/*-----------------------------------------------------------------------
* START: High -> Low on SDA while SCL is High
*/
static void send_start(void)
{
#ifdef CONFIG_MPC8260
volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
#endif
#ifdef CONFIG_8xx
volatile immap_t *immr = (immap_t *)CFG_IMMR;
#endif
I2C_DELAY;
I2C_SDA(1);
I2C_ACTIVE;
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_SDA(0);
I2C_DELAY;
}
/*-----------------------------------------------------------------------
* STOP: Low -> High on SDA while SCL is High
*/
static void send_stop(void)
{
#ifdef CONFIG_MPC8260
volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
#endif
#ifdef CONFIG_8xx
volatile immap_t *immr = (immap_t *)CFG_IMMR;
#endif
I2C_SCL(0);
I2C_DELAY;
I2C_SDA(0);
I2C_ACTIVE;
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_SDA(1);
I2C_DELAY;
I2C_TRISTATE;
}
/*-----------------------------------------------------------------------
* ack should be I2C_ACK or I2C_NOACK
*/
static void send_ack(int ack)
{
#ifdef CONFIG_MPC8260
volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
#endif
#ifdef CONFIG_8xx
volatile immap_t *immr = (immap_t *)CFG_IMMR;
#endif
I2C_SCL(0);
I2C_DELAY;
I2C_ACTIVE;
I2C_SDA(ack);
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_DELAY;
I2C_SCL(0);
I2C_DELAY;
}
/*-----------------------------------------------------------------------
* Send 8 bits and look for an acknowledgement.
*/
static int write_byte(uchar data)
{
#ifdef CONFIG_MPC8260
volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
#endif
#ifdef CONFIG_8xx
volatile immap_t *immr = (immap_t *)CFG_IMMR;
#endif
int j;
int nack;
I2C_ACTIVE;
for(j = 0; j < 8; j++) {
I2C_SCL(0);
I2C_DELAY;
I2C_SDA(data & 0x80);
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_DELAY;
data <<= 1;
}
/*
* Look for an <ACK>(negative logic) and return it.
*/
I2C_SCL(0);
I2C_DELAY;
I2C_SDA(1);
I2C_TRISTATE;
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_DELAY;
nack = I2C_READ;
I2C_SCL(0);
I2C_DELAY;
I2C_ACTIVE;
return(nack); /* not a nack is an ack */
}
/*-----------------------------------------------------------------------
* if ack == I2C_ACK, ACK the byte so can continue reading, else
* send I2C_NOACK to end the read.
*/
static uchar read_byte(int ack)
{
#ifdef CONFIG_MPC8260
volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
#endif
#ifdef CONFIG_8xx
volatile immap_t *immr = (immap_t *)CFG_IMMR;
#endif
int data;
int j;
/*
* Read 8 bits, MSB first.
*/
I2C_TRISTATE;
data = 0;
for(j = 0; j < 8; j++) {
I2C_SCL(0);
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
data <<= 1;
data |= I2C_READ;
I2C_DELAY;
}
send_ack(ack);
return(data);
}
/*=====================================================================*/
/* Public Functions */
/*=====================================================================*/
/*-----------------------------------------------------------------------
* Initialization
*/
void i2c_init (int speed, int slaveaddr)
{
/*
* WARNING: Do NOT save speed in a static variable: if the
* I2C routines are called before RAM is initialized (to read
* the DIMM SPD, for instance), RAM won't be usable and your
* system will crash.
*/
send_reset ();
}
/*-----------------------------------------------------------------------
* Probe to see if a chip is present. Also good for checking for the
* completion of EEPROM writes since the chip stops responding until
* the write completes (typically 10mSec).
*/
int i2c_probe(uchar addr)
{
int rc;
/*
* perform 1 byte write transaction with just address byte
* (fake write)
*/
send_start();
rc = write_byte ((addr << 1) | 0);
send_stop();
return (rc ? 1 : 0);
}
/*-----------------------------------------------------------------------
* Read bytes
*/
int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
{
int shift;
PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
chip, addr, alen, buffer, len);
#ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
/*
* EEPROM chips that implement "address overflow" are ones
* like Catalyst 24WC04/08/16 which has 9/10/11 bits of
* address and the extra bits end up in the "chip address"
* bit slots. This makes a 24WC08 (1Kbyte) chip look like
* four 256 byte chips.
*
* Note that we consider the length of the address field to
* still be one byte because the extra address bits are
* hidden in the chip address.
*/
chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW);
PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
chip, addr);
#endif
/*
* Do the addressing portion of a write cycle to set the
* chip's address pointer. If the address length is zero,
* don't do the normal write cycle to set the address pointer,
* there is no address pointer in this chip.
*/
send_start();
if(alen > 0) {
if(write_byte(chip << 1)) { /* write cycle */
send_stop();
PRINTD("i2c_read, no chip responded %02X\n", chip);
return(1);
}
shift = (alen-1) * 8;
while(alen-- > 0) {
if(write_byte(addr >> shift)) {
PRINTD("i2c_read, address not <ACK>ed\n");
return(1);
}
shift -= 8;
}
send_stop(); /* reportedly some chips need a full stop */
send_start();
}
/*
* Send the chip address again, this time for a read cycle.
* Then read the data. On the last byte, we do a NACK instead
* of an ACK(len == 0) to terminate the read.
*/
write_byte((chip << 1) | 1); /* read cycle */
while(len-- > 0) {
*buffer++ = read_byte(len == 0);
}
send_stop();
return(0);
}
/*-----------------------------------------------------------------------
* Write bytes
*/
int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
{
int shift, failures = 0;
PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
chip, addr, alen, buffer, len);
send_start();
if(write_byte(chip << 1)) { /* write cycle */
send_stop();
PRINTD("i2c_write, no chip responded %02X\n", chip);
return(1);
}
shift = (alen-1) * 8;
while(alen-- > 0) {
if(write_byte(addr >> shift)) {
PRINTD("i2c_write, address not <ACK>ed\n");
return(1);
}
shift -= 8;
}
while(len-- > 0) {
if(write_byte(*buffer++)) {
failures++;
}
}
send_stop();
return(failures);
}
/*-----------------------------------------------------------------------
* Read a register
*/
uchar i2c_reg_read(uchar i2c_addr, uchar reg)
{
uchar buf;
i2c_read(i2c_addr, reg, 1, &buf, 1);
return(buf);
}
/*-----------------------------------------------------------------------
* Write a register
*/
void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
{
i2c_write(i2c_addr, reg, 1, &val, 1);
}
#endif /* CONFIG_SOFT_I2C */
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