187 lines
4.0 KiB
C
187 lines
4.0 KiB
C
/*
|
|
* i2c-algo-sgi.c: i2c driver algorithms for SGI adapters.
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU General Public
|
|
* License version 2 as published by the Free Software Foundation.
|
|
*
|
|
* Copyright (C) 2003 Ladislav Michl <ladis@linux-mips.org>
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/delay.h>
|
|
|
|
#include <linux/i2c.h>
|
|
#include <linux/i2c-algo-sgi.h>
|
|
|
|
|
|
#define SGI_I2C_FORCE_IDLE (0 << 0)
|
|
#define SGI_I2C_NOT_IDLE (1 << 0)
|
|
#define SGI_I2C_WRITE (0 << 1)
|
|
#define SGI_I2C_READ (1 << 1)
|
|
#define SGI_I2C_RELEASE_BUS (0 << 2)
|
|
#define SGI_I2C_HOLD_BUS (1 << 2)
|
|
#define SGI_I2C_XFER_DONE (0 << 4)
|
|
#define SGI_I2C_XFER_BUSY (1 << 4)
|
|
#define SGI_I2C_ACK (0 << 5)
|
|
#define SGI_I2C_NACK (1 << 5)
|
|
#define SGI_I2C_BUS_OK (0 << 7)
|
|
#define SGI_I2C_BUS_ERR (1 << 7)
|
|
|
|
#define get_control() adap->getctrl(adap->data)
|
|
#define set_control(val) adap->setctrl(adap->data, val)
|
|
#define read_data() adap->rdata(adap->data)
|
|
#define write_data(val) adap->wdata(adap->data, val)
|
|
|
|
|
|
static int wait_xfer_done(struct i2c_algo_sgi_data *adap)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < adap->xfer_timeout; i++) {
|
|
if ((get_control() & SGI_I2C_XFER_BUSY) == 0)
|
|
return 0;
|
|
udelay(1);
|
|
}
|
|
|
|
return -ETIMEDOUT;
|
|
}
|
|
|
|
static int wait_ack(struct i2c_algo_sgi_data *adap)
|
|
{
|
|
int i;
|
|
|
|
if (wait_xfer_done(adap))
|
|
return -ETIMEDOUT;
|
|
for (i = 0; i < adap->ack_timeout; i++) {
|
|
if ((get_control() & SGI_I2C_NACK) == 0)
|
|
return 0;
|
|
udelay(1);
|
|
}
|
|
|
|
return -ETIMEDOUT;
|
|
}
|
|
|
|
static int force_idle(struct i2c_algo_sgi_data *adap)
|
|
{
|
|
int i;
|
|
|
|
set_control(SGI_I2C_FORCE_IDLE);
|
|
for (i = 0; i < adap->xfer_timeout; i++) {
|
|
if ((get_control() & SGI_I2C_NOT_IDLE) == 0)
|
|
goto out;
|
|
udelay(1);
|
|
}
|
|
return -ETIMEDOUT;
|
|
out:
|
|
if (get_control() & SGI_I2C_BUS_ERR)
|
|
return -EIO;
|
|
return 0;
|
|
}
|
|
|
|
static int do_address(struct i2c_algo_sgi_data *adap, unsigned int addr,
|
|
int rd)
|
|
{
|
|
if (rd)
|
|
set_control(SGI_I2C_NOT_IDLE);
|
|
/* Check if bus is idle, eventually force it to do so */
|
|
if (get_control() & SGI_I2C_NOT_IDLE)
|
|
if (force_idle(adap))
|
|
return -EIO;
|
|
/* Write out the i2c chip address and specify operation */
|
|
set_control(SGI_I2C_HOLD_BUS | SGI_I2C_WRITE | SGI_I2C_NOT_IDLE);
|
|
if (rd)
|
|
addr |= 1;
|
|
write_data(addr);
|
|
if (wait_ack(adap))
|
|
return -EIO;
|
|
return 0;
|
|
}
|
|
|
|
static int i2c_read(struct i2c_algo_sgi_data *adap, unsigned char *buf,
|
|
unsigned int len)
|
|
{
|
|
int i;
|
|
|
|
set_control(SGI_I2C_HOLD_BUS | SGI_I2C_READ | SGI_I2C_NOT_IDLE);
|
|
for (i = 0; i < len; i++) {
|
|
if (wait_xfer_done(adap))
|
|
return -EIO;
|
|
buf[i] = read_data();
|
|
}
|
|
set_control(SGI_I2C_RELEASE_BUS | SGI_I2C_FORCE_IDLE);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
static int i2c_write(struct i2c_algo_sgi_data *adap, unsigned char *buf,
|
|
unsigned int len)
|
|
{
|
|
int i;
|
|
|
|
/* We are already in write state */
|
|
for (i = 0; i < len; i++) {
|
|
write_data(buf[i]);
|
|
if (wait_ack(adap))
|
|
return -EIO;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int sgi_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs,
|
|
int num)
|
|
{
|
|
struct i2c_algo_sgi_data *adap = i2c_adap->algo_data;
|
|
struct i2c_msg *p;
|
|
int i, err = 0;
|
|
|
|
for (i = 0; !err && i < num; i++) {
|
|
p = &msgs[i];
|
|
err = do_address(adap, p->addr, p->flags & I2C_M_RD);
|
|
if (err || !p->len)
|
|
continue;
|
|
if (p->flags & I2C_M_RD)
|
|
err = i2c_read(adap, p->buf, p->len);
|
|
else
|
|
err = i2c_write(adap, p->buf, p->len);
|
|
}
|
|
|
|
return (err < 0) ? err : i;
|
|
}
|
|
|
|
static u32 sgi_func(struct i2c_adapter *adap)
|
|
{
|
|
return I2C_FUNC_SMBUS_EMUL;
|
|
}
|
|
|
|
static struct i2c_algorithm sgi_algo = {
|
|
.master_xfer = sgi_xfer,
|
|
.functionality = sgi_func,
|
|
};
|
|
|
|
/*
|
|
* registering functions to load algorithms at runtime
|
|
*/
|
|
int i2c_sgi_add_bus(struct i2c_adapter *adap)
|
|
{
|
|
adap->algo = &sgi_algo;
|
|
|
|
return i2c_add_adapter(adap);
|
|
}
|
|
|
|
|
|
int i2c_sgi_del_bus(struct i2c_adapter *adap)
|
|
{
|
|
return i2c_del_adapter(adap);
|
|
}
|
|
|
|
EXPORT_SYMBOL(i2c_sgi_add_bus);
|
|
EXPORT_SYMBOL(i2c_sgi_del_bus);
|
|
|
|
MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>");
|
|
MODULE_DESCRIPTION("I2C-Bus SGI algorithm");
|
|
MODULE_LICENSE("GPL");
|