u-boot/board/pcippc2/i2c.c
2002-11-03 00:24:07 +00:00

258 lines
4.3 KiB
C

/*
* (C) Copyright 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
*/
#include <config.h>
#include <common.h>
#include <asm/io.h>
#include "hardware.h"
#include "i2c.h"
static void i2c_start (void);
static void i2c_stop (void);
static int i2c_write (u8 data);
static void i2c_read (u8 * data);
static inline void i2c_port_start (void);
static inline void i2c_clock (unsigned int val);
static inline void i2c_data (unsigned int val);
static inline unsigned int
i2c_in (void);
static inline void i2c_write_bit (unsigned int val);
static inline unsigned int
i2c_read_bit (void);
static inline void i2c_udelay (unsigned int time);
int i2c_read_byte (
u8 * data,
u8 dev,
u8 offset)
{
int err = 0;
i2c_start();
err = ! i2c_write(dev);
if (! err)
{
err = ! i2c_write(offset);
}
if (! err)
{
i2c_start();
}
if (! err)
{
err = ! i2c_write(dev | 0x01);
}
if (! err)
{
i2c_read(data);
}
i2c_stop();
return ! err;
}
static inline void i2c_udelay (
unsigned int time)
{
int v;
asm volatile("mtdec %0" : : "r" (time * ((CFG_BUS_CLK / 4) / 1000000)));
do
{
asm volatile("isync; mfdec %0" : "=r" (v));
} while (v >= 0);
}
/* Low-level hardware access
*/
#define BIT_GPDATA 0x80000000
#define BIT_GPCLK 0x40000000
static inline void i2c_port_start (void)
{
out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) & ~(BIT_GPCLK | BIT_GPDATA));
out32(REG(CPC0, GPOUT), in32(REG(CPC0, GPOUT)) & ~(BIT_GPCLK | BIT_GPDATA));
iobarrier_rw();
i2c_udelay(1);
}
static inline void i2c_clock (
unsigned int val)
{
if (val)
{
out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) & ~BIT_GPCLK);
}
else
{
out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) | BIT_GPCLK);
}
iobarrier_rw();
i2c_udelay(1);
}
static inline void i2c_data (
unsigned int val)
{
if (val)
{
out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) & ~BIT_GPDATA);
}
else
{
out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) | BIT_GPDATA);
}
iobarrier_rw();
i2c_udelay(1);
}
static inline unsigned int i2c_in (void)
{
unsigned int val = ((in32(REG(CPC0, GPIN)) & BIT_GPDATA) != 0)?1:0;
iobarrier_rw();
return val;
}
/* Protocol implementation
*/
static inline void i2c_write_bit (
unsigned int val)
{
i2c_data(val);
i2c_udelay(10);
i2c_clock(1);
i2c_udelay(10);
i2c_clock(0);
i2c_udelay(10);
}
static inline unsigned int i2c_read_bit (void)
{
unsigned int val;
i2c_data(1);
i2c_udelay(10);
i2c_clock(1);
i2c_udelay(10);
val = i2c_in();
i2c_clock(0);
i2c_udelay(10);
return val;
}
unsigned int i2c_reset (void)
{
unsigned int val;
int i;
i2c_port_start();
i=0;
do {
i2c_udelay(10);
i2c_clock(0);
i2c_udelay(10);
i2c_clock(1);
i2c_udelay(10);
val = i2c_in();
i++;
} while ((i<9)&&(val==0));
return (val);
}
static void i2c_start (void)
{
i2c_data(1);
i2c_clock(1);
i2c_udelay(10);
i2c_data(0);
i2c_udelay(10);
i2c_clock(0);
i2c_udelay(10);
}
static void i2c_stop (void)
{
i2c_data(0);
i2c_udelay(10);
i2c_clock(1);
i2c_udelay(10);
i2c_data(1);
i2c_udelay(10);
}
static int i2c_write (
u8 data)
{
unsigned int i;
for (i = 0; i < 8; i++)
{
i2c_write_bit(data >> 7);
data <<= 1;
}
return i2c_read_bit() == 0;
}
static void i2c_read (
u8 * data)
{
unsigned int i;
u8 val = 0;
for (i = 0; i < 8; i++)
{
val <<= 1;
val |= i2c_read_bit();
}
*data = val;
i2c_write_bit(1); /* NoAck */
}