mb862xx-i2c.c

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/*
 * Coral-P(A)/Lime I2C adapter driver
 *
 * (C) 2011 DENX Software Engineering, Anatolij Gustschin <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/fb.h>
#include <linux/i2c.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/export.h>

#include "mb862xxfb.h"
#include "mb862xx_reg.h"

static int mb862xx_i2c_wait_event(struct i2c_adapter *adap)
{
    struct mb862xxfb_par *par = adap->algo_data;
    u32 reg;

    do {
        udelay(10);
        reg = inreg(i2c, GC_I2C_BCR);
        if (reg & (I2C_INT | I2C_BER))
            break;
    } while (1);

    return (reg & I2C_BER) ? 0 : 1;
}

static int mb862xx_i2c_do_address(struct i2c_adapter *adap, int addr)
{
    struct mb862xxfb_par *par = adap->algo_data;

    outreg(i2c, GC_I2C_DAR, addr);
    outreg(i2c, GC_I2C_CCR, I2C_CLOCK_AND_ENABLE);
    outreg(i2c, GC_I2C_BCR, par->i2c_rs ? I2C_REPEATED_START : I2C_START);
    if (!mb862xx_i2c_wait_event(adap))
        return -EIO;
    par->i2c_rs = !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
    return par->i2c_rs;
}

static int mb862xx_i2c_write_byte(struct i2c_adapter *adap, u8 byte)
{
    struct mb862xxfb_par *par = adap->algo_data;

    outreg(i2c, GC_I2C_DAR, byte);
    outreg(i2c, GC_I2C_BCR, I2C_START);
    if (!mb862xx_i2c_wait_event(adap))
        return -EIO;
    return !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
}

static int mb862xx_i2c_read_byte(struct i2c_adapter *adap, u8 *byte, int last)
{
    struct mb862xxfb_par *par = adap->algo_data;

    outreg(i2c, GC_I2C_BCR, I2C_START | (last ? 0 : I2C_ACK));
    if (!mb862xx_i2c_wait_event(adap))
        return 0;
    *byte = inreg(i2c, GC_I2C_DAR);
    return 1;
}

static void mb862xx_i2c_stop(struct i2c_adapter *adap)
{
    struct mb862xxfb_par *par = adap->algo_data;

    outreg(i2c, GC_I2C_BCR, I2C_STOP);
    outreg(i2c, GC_I2C_CCR, I2C_DISABLE);
    par->i2c_rs = 0;
}

static int mb862xx_i2c_read(struct i2c_adapter *adap, struct i2c_msg *m)
{
    int i, ret = 0;
    int last = m->len - 1;

    for (i = 0; i < m->len; i++) {
        if (!mb862xx_i2c_read_byte(adap, &m->buf[i], i == last)) {
            ret = -EIO;
            break;
        }
    }
    return ret;
}

static int mb862xx_i2c_write(struct i2c_adapter *adap, struct i2c_msg *m)
{
    int i, ret = 0;

    for (i = 0; i < m->len; i++) {
        if (!mb862xx_i2c_write_byte(adap, m->buf[i])) {
            ret = -EIO;
            break;
        }
    }
    return ret;
}

static int mb862xx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
            int num)
{
    struct mb862xxfb_par *par = adap->algo_data;
    struct i2c_msg *m;
    int addr;
    int i = 0, err = 0;

    dev_dbg(par->dev, "%s: %d msgs\n", __func__, num);

    for (i = 0; i < num; i++) {
        m = &msgs[i];
        if (!m->len) {
            dev_dbg(par->dev, "%s: null msgs\n", __func__);
            continue;
        }
        addr = m->addr;
        if (m->flags & I2C_M_RD)
            addr |= 1;

        err = mb862xx_i2c_do_address(adap, addr);
        if (err < 0)
            break;
        if (m->flags & I2C_M_RD)
            err = mb862xx_i2c_read(adap, m);
        else
            err = mb862xx_i2c_write(adap, m);
    }

    if (i)
        mb862xx_i2c_stop(adap);

    return (err < 0) ? err : i;
}

static u32 mb862xx_func(struct i2c_adapter *adap)
{
    return I2C_FUNC_SMBUS_BYTE_DATA;
}

static const struct i2c_algorithm mb862xx_algo = {
    .master_xfer    = mb862xx_xfer,
    .functionality  = mb862xx_func,
};

static struct i2c_adapter mb862xx_i2c_adapter = {
    .name       = "MB862xx I2C adapter",
    .algo       = &mb862xx_algo,
    .owner      = THIS_MODULE,
};

int mb862xx_i2c_init(struct mb862xxfb_par *par)
{
    int ret;

    mb862xx_i2c_adapter.algo_data = par;
    par->adap = &mb862xx_i2c_adapter;

    ret = i2c_add_adapter(par->adap);
    if (ret < 0) {
        dev_err(par->dev, "failed to add %s\n",
            mb862xx_i2c_adapter.name);
    }
    return ret;
}

void mb862xx_i2c_exit(struct mb862xxfb_par *par)
{
    if (par->adap) {
        i2c_del_adapter(par->adap);
        par->adap = NULL;
    }
}