180 lines
3.9 KiB
C
180 lines
3.9 KiB
C
/*
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* i2c-algo-sgi.c: i2c driver algorithm used by the VINO (SGI Indy) and
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* MACE (SGI O2) chips.
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License version 2 as published by the Free Software Foundation.
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*
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* Copyright (C) 2003 Ladislav Michl <ladis@linux-mips.org>
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/delay.h>
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#include <linux/i2c.h>
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#include <linux/i2c-algo-sgi.h>
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#define SGI_I2C_FORCE_IDLE (0 << 0)
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#define SGI_I2C_NOT_IDLE (1 << 0)
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#define SGI_I2C_WRITE (0 << 1)
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#define SGI_I2C_READ (1 << 1)
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#define SGI_I2C_RELEASE_BUS (0 << 2)
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#define SGI_I2C_HOLD_BUS (1 << 2)
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#define SGI_I2C_XFER_DONE (0 << 4)
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#define SGI_I2C_XFER_BUSY (1 << 4)
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#define SGI_I2C_ACK (0 << 5)
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#define SGI_I2C_NACK (1 << 5)
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#define SGI_I2C_BUS_OK (0 << 7)
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#define SGI_I2C_BUS_ERR (1 << 7)
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#define get_control() adap->getctrl(adap->data)
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#define set_control(val) adap->setctrl(adap->data, val)
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#define read_data() adap->rdata(adap->data)
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#define write_data(val) adap->wdata(adap->data, val)
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static int wait_xfer_done(struct i2c_algo_sgi_data *adap)
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{
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int i;
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for (i = 0; i < adap->xfer_timeout; i++) {
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if ((get_control() & SGI_I2C_XFER_BUSY) == 0)
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return 0;
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udelay(1);
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}
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return -ETIMEDOUT;
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}
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static int wait_ack(struct i2c_algo_sgi_data *adap)
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{
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int i;
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if (wait_xfer_done(adap))
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return -ETIMEDOUT;
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for (i = 0; i < adap->ack_timeout; i++) {
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if ((get_control() & SGI_I2C_NACK) == 0)
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return 0;
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udelay(1);
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}
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return -ETIMEDOUT;
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}
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static int force_idle(struct i2c_algo_sgi_data *adap)
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{
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int i;
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set_control(SGI_I2C_FORCE_IDLE);
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for (i = 0; i < adap->xfer_timeout; i++) {
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if ((get_control() & SGI_I2C_NOT_IDLE) == 0)
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goto out;
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udelay(1);
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}
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return -ETIMEDOUT;
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out:
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if (get_control() & SGI_I2C_BUS_ERR)
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return -EIO;
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return 0;
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}
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static int do_address(struct i2c_algo_sgi_data *adap, unsigned int addr,
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int rd)
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{
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if (rd)
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set_control(SGI_I2C_NOT_IDLE);
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/* Check if bus is idle, eventually force it to do so */
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if (get_control() & SGI_I2C_NOT_IDLE)
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if (force_idle(adap))
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return -EIO;
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/* Write out the i2c chip address and specify operation */
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set_control(SGI_I2C_HOLD_BUS | SGI_I2C_WRITE | SGI_I2C_NOT_IDLE);
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if (rd)
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addr |= 1;
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write_data(addr);
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if (wait_ack(adap))
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return -EIO;
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return 0;
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}
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static int i2c_read(struct i2c_algo_sgi_data *adap, unsigned char *buf,
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unsigned int len)
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{
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int i;
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set_control(SGI_I2C_HOLD_BUS | SGI_I2C_READ | SGI_I2C_NOT_IDLE);
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for (i = 0; i < len; i++) {
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if (wait_xfer_done(adap))
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return -EIO;
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buf[i] = read_data();
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}
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set_control(SGI_I2C_RELEASE_BUS | SGI_I2C_FORCE_IDLE);
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return 0;
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}
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static int i2c_write(struct i2c_algo_sgi_data *adap, unsigned char *buf,
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unsigned int len)
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{
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int i;
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/* We are already in write state */
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for (i = 0; i < len; i++) {
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write_data(buf[i]);
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if (wait_ack(adap))
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return -EIO;
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}
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return 0;
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}
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static int sgi_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs,
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int num)
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{
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struct i2c_algo_sgi_data *adap = i2c_adap->algo_data;
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struct i2c_msg *p;
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int i, err = 0;
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for (i = 0; !err && i < num; i++) {
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p = &msgs[i];
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err = do_address(adap, p->addr, p->flags & I2C_M_RD);
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if (err || !p->len)
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continue;
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if (p->flags & I2C_M_RD)
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err = i2c_read(adap, p->buf, p->len);
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else
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err = i2c_write(adap, p->buf, p->len);
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}
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return (err < 0) ? err : i;
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}
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static u32 sgi_func(struct i2c_adapter *adap)
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{
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return I2C_FUNC_SMBUS_EMUL;
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}
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static const struct i2c_algorithm sgi_algo = {
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.master_xfer = sgi_xfer,
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.functionality = sgi_func,
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};
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/*
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* registering functions to load algorithms at runtime
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*/
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int i2c_sgi_add_bus(struct i2c_adapter *adap)
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{
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adap->algo = &sgi_algo;
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return i2c_add_adapter(adap);
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}
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EXPORT_SYMBOL(i2c_sgi_add_bus);
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MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>");
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MODULE_DESCRIPTION("I2C-Bus SGI algorithm");
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MODULE_LICENSE("GPL");
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