stk1160-i2c.c

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/*
 * STK1160 driver
 *
 * Copyright (C) 2012 Ezequiel Garcia
 * <elezegarcia--a.t--gmail.com>
 *
 * Based on Easycap driver by R.M. Thomas
 *  Copyright (C) 2010 R.M. Thomas
 *  <rmthomas--a.t--sciolus.org>
 *
 * 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.
 *
 */

#include <linux/module.h>
#include <linux/usb.h>
#include <linux/i2c.h>

#include "stk1160.h"
#include "stk1160-reg.h"

static unsigned int i2c_debug;
module_param(i2c_debug, int, 0644);
MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");

#define dprintk_i2c(fmt, args...)               \
do {                                \
    if (i2c_debug)                      \
        printk(KERN_DEBUG fmt, ##args);         \
} while (0)

static int stk1160_i2c_busy_wait(struct stk1160 *dev, u8 wait_bit_mask)
{
    unsigned long end;
    u8 flag;

    /* Wait until read/write finish bit is set */
    end = jiffies + msecs_to_jiffies(STK1160_I2C_TIMEOUT);
    while (time_is_after_jiffies(end)) {

        stk1160_read_reg(dev, STK1160_SICTL+1, &flag);
        /* read/write done? */
        if (flag & wait_bit_mask)
            goto done;

        usleep_range(10 * USEC_PER_MSEC, 20 * USEC_PER_MSEC);
    }

    return -ETIMEDOUT;

done:
    return 0;
}

static int stk1160_i2c_write_reg(struct stk1160 *dev, u8 addr,
        u8 reg, u8 value)
{
    int rc;

    /* Set serial device address */
    rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
    if (rc < 0)
        return rc;

    /* Set i2c device register sub-address */
    rc = stk1160_write_reg(dev, STK1160_SBUSW_WA, reg);
    if (rc < 0)
        return rc;

    /* Set i2c device register value */
    rc = stk1160_write_reg(dev, STK1160_SBUSW_WD, value);
    if (rc < 0)
        return rc;

    /* Start write now */
    rc = stk1160_write_reg(dev, STK1160_SICTL, 0x01);
    if (rc < 0)
        return rc;

    rc = stk1160_i2c_busy_wait(dev, 0x04);
    if (rc < 0)
        return rc;

    return 0;
}

static int stk1160_i2c_read_reg(struct stk1160 *dev, u8 addr,
        u8 reg, u8 *value)
{
    int rc;

    /* Set serial device address */
    rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
    if (rc < 0)
        return rc;

    /* Set i2c device register sub-address */
    rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, reg);
    if (rc < 0)
        return rc;

    /* Start read now */
    rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
    if (rc < 0)
        return rc;

    rc = stk1160_i2c_busy_wait(dev, 0x01);
    if (rc < 0)
        return rc;

    stk1160_read_reg(dev, STK1160_SBUSR_RD, value);
    if (rc < 0)
        return rc;

    return 0;
}

/*
 * stk1160_i2c_check_for_device()
 * check if there is a i2c_device at the supplied address
 */
static int stk1160_i2c_check_for_device(struct stk1160 *dev,
        unsigned char addr)
{
    int rc;

    /* Set serial device address */
    rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
    if (rc < 0)
        return rc;

    /* Set device sub-address, we'll chip version reg */
    rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, 0x00);
    if (rc < 0)
        return rc;

    /* Start read now */
    rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
    if (rc < 0)
        return rc;

    rc = stk1160_i2c_busy_wait(dev, 0x01);
    if (rc < 0)
        return -ENODEV;

    return 0;
}

/*
 * stk1160_i2c_xfer()
 * the main i2c transfer function
 */
static int stk1160_i2c_xfer(struct i2c_adapter *i2c_adap,
               struct i2c_msg msgs[], int num)
{
    struct stk1160 *dev = i2c_adap->algo_data;
    int addr, rc, i;

    for (i = 0; i < num; i++) {
        addr = msgs[i].addr << 1;
        dprintk_i2c("%s: addr=%x", __func__, addr);

        if (!msgs[i].len) {
            /* no len: check only for device presence */
            rc = stk1160_i2c_check_for_device(dev, addr);
            if (rc < 0) {
                dprintk_i2c(" no device\n");
                return rc;
            }

        } else if (msgs[i].flags & I2C_M_RD) {
            /* read request without preceding register selection */
            dprintk_i2c(" subaddr not selected");
            rc = -EOPNOTSUPP;
            goto err;

        } else if (i + 1 < num && msgs[i].len <= 2 &&
               (msgs[i + 1].flags & I2C_M_RD) &&
               msgs[i].addr == msgs[i + 1].addr) {

            if (msgs[i].len != 1 || msgs[i + 1].len != 1) {
                dprintk_i2c(" len not supported");
                rc = -EOPNOTSUPP;
                goto err;
            }

            dprintk_i2c(" subaddr=%x", msgs[i].buf[0]);

            rc = stk1160_i2c_read_reg(dev, addr, msgs[i].buf[0],
                msgs[i + 1].buf);

            dprintk_i2c(" read=%x", *msgs[i + 1].buf);

            /* consumed two msgs, so we skip one of them */
            i++;

        } else {
            if (msgs[i].len != 2) {
                dprintk_i2c(" len not supported");
                rc = -EOPNOTSUPP;
                goto err;
            }

            dprintk_i2c(" subaddr=%x write=%x",
                msgs[i].buf[0],  msgs[i].buf[1]);

            rc = stk1160_i2c_write_reg(dev, addr, msgs[i].buf[0],
                msgs[i].buf[1]);
        }

        if (rc < 0)
            goto err;
        dprintk_i2c(" OK\n");
    }

    return num;
err:
    dprintk_i2c(" ERROR: %d\n", rc);
    return num;
}

/*
 * functionality(), what da heck is this?
 */
static u32 functionality(struct i2c_adapter *adap)
{
    return I2C_FUNC_SMBUS_EMUL;
}

static struct i2c_algorithm algo = {
    .master_xfer   = stk1160_i2c_xfer,
    .functionality = functionality,
};

static struct i2c_adapter adap_template = {
    .owner = THIS_MODULE,
    .name = "stk1160",
    .algo = &algo,
};

static struct i2c_client client_template = {
    .name = "stk1160 internal",
};

/*
 * stk1160_i2c_register()
 * register i2c bus
 */
int stk1160_i2c_register(struct stk1160 *dev)
{
    int rc;

    dev->i2c_adap = adap_template;
    dev->i2c_adap.dev.parent = dev->dev;
    strcpy(dev->i2c_adap.name, "stk1160");
    dev->i2c_adap.algo_data = dev;

    i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);

    rc = i2c_add_adapter(&dev->i2c_adap);
    if (rc < 0) {
        stk1160_err("cannot add i2c adapter (%d)\n", rc);
        return rc;
    }

    dev->i2c_client = client_template;
    dev->i2c_client.adapter = &dev->i2c_adap;

    /* Set i2c clock divider device address */
    stk1160_write_reg(dev, STK1160_SICTL_CD,  0x0f);

    /* ??? */
    stk1160_write_reg(dev, STK1160_ASIC + 3,  0x00);

    return 0;
}

/*
 * stk1160_i2c_unregister()
 * unregister i2c_bus
 */
int stk1160_i2c_unregister(struct stk1160 *dev)
{
    i2c_del_adapter(&dev->i2c_adap);
    return 0;
}