ad5398.c

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/*
 * Voltage and current regulation for AD5398 and AD5821
 *
 * Copyright 2010 Analog Devices Inc.
 *
 * Enter bugs at http://blackfin.uclinux.org/
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>

#define AD5398_CURRENT_EN_MASK  0x8000

struct ad5398_chip_info {
    struct i2c_client *client;
    int min_uA;
    int max_uA;
    unsigned int current_level;
    unsigned int current_mask;
    unsigned int current_offset;
    struct regulator_dev *rdev;
};

static int ad5398_calc_current(struct ad5398_chip_info *chip,
    unsigned selector)
{
    unsigned range_uA = chip->max_uA - chip->min_uA;

    return chip->min_uA + (selector * range_uA / chip->current_level);
}

static int ad5398_read_reg(struct i2c_client *client, unsigned short *data)
{
    unsigned short val;
    int ret;

    ret = i2c_master_recv(client, (char *)&val, 2);
    if (ret < 0) {
        dev_err(&client->dev, "I2C read error\n");
        return ret;
    }
    *data = be16_to_cpu(val);

    return ret;
}

static int ad5398_write_reg(struct i2c_client *client, const unsigned short data)
{
    unsigned short val;
    int ret;

    val = cpu_to_be16(data);
    ret = i2c_master_send(client, (char *)&val, 2);
    if (ret < 0)
        dev_err(&client->dev, "I2C write error\n");

    return ret;
}

static int ad5398_get_current_limit(struct regulator_dev *rdev)
{
    struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
    struct i2c_client *client = chip->client;
    unsigned short data;
    int ret;

    ret = ad5398_read_reg(client, &data);
    if (ret < 0)
        return ret;

    ret = (data & chip->current_mask) >> chip->current_offset;

    return ad5398_calc_current(chip, ret);
}

static int ad5398_set_current_limit(struct regulator_dev *rdev, int min_uA, int max_uA)
{
    struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
    struct i2c_client *client = chip->client;
    unsigned range_uA = chip->max_uA - chip->min_uA;
    unsigned selector;
    unsigned short data;
    int ret;

    if (min_uA < chip->min_uA)
        min_uA = chip->min_uA;
    if (max_uA > chip->max_uA)
        max_uA = chip->max_uA;

    if (min_uA > chip->max_uA || max_uA < chip->min_uA)
        return -EINVAL;

    selector = DIV_ROUND_UP((min_uA - chip->min_uA) * chip->current_level,
                range_uA);
    if (ad5398_calc_current(chip, selector) > max_uA)
        return -EINVAL;

    dev_dbg(&client->dev, "changing current %duA\n",
        ad5398_calc_current(chip, selector));

    /* read chip enable bit */
    ret = ad5398_read_reg(client, &data);
    if (ret < 0)
        return ret;

    /* prepare register data */
    selector = (selector << chip->current_offset) & chip->current_mask;
    data = (unsigned short)selector | (data & AD5398_CURRENT_EN_MASK);

    /* write the new current value back as well as enable bit */
    ret = ad5398_write_reg(client, data);

    return ret;
}

static int ad5398_is_enabled(struct regulator_dev *rdev)
{
    struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
    struct i2c_client *client = chip->client;
    unsigned short data;
    int ret;

    ret = ad5398_read_reg(client, &data);
    if (ret < 0)
        return ret;

    if (data & AD5398_CURRENT_EN_MASK)
        return 1;
    else
        return 0;
}

static int ad5398_enable(struct regulator_dev *rdev)
{
    struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
    struct i2c_client *client = chip->client;
    unsigned short data;
    int ret;

    ret = ad5398_read_reg(client, &data);
    if (ret < 0)
        return ret;

    if (data & AD5398_CURRENT_EN_MASK)
        return 0;

    data |= AD5398_CURRENT_EN_MASK;

    ret = ad5398_write_reg(client, data);

    return ret;
}

static int ad5398_disable(struct regulator_dev *rdev)
{
    struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
    struct i2c_client *client = chip->client;
    unsigned short data;
    int ret;

    ret = ad5398_read_reg(client, &data);
    if (ret < 0)
        return ret;

    if (!(data & AD5398_CURRENT_EN_MASK))
        return 0;

    data &= ~AD5398_CURRENT_EN_MASK;

    ret = ad5398_write_reg(client, data);

    return ret;
}

static struct regulator_ops ad5398_ops = {
    .get_current_limit = ad5398_get_current_limit,
    .set_current_limit = ad5398_set_current_limit,
    .enable = ad5398_enable,
    .disable = ad5398_disable,
    .is_enabled = ad5398_is_enabled,
};

static const struct regulator_desc ad5398_reg = {
    .name = "isink",
    .id = 0,
    .ops = &ad5398_ops,
    .type = REGULATOR_CURRENT,
    .owner = THIS_MODULE,
};

struct ad5398_current_data_format {
    int current_bits;
    int current_offset;
    int min_uA;
    int max_uA;
};

static const struct ad5398_current_data_format df_10_4_120 = {10, 4, 0, 120000};

static const struct i2c_device_id ad5398_id[] = {
    { "ad5398", (kernel_ulong_t)&df_10_4_120 },
    { "ad5821", (kernel_ulong_t)&df_10_4_120 },
    { }
};
MODULE_DEVICE_TABLE(i2c, ad5398_id);

static int __devinit ad5398_probe(struct i2c_client *client,
                const struct i2c_device_id *id)
{
    struct regulator_init_data *init_data = client->dev.platform_data;
    struct regulator_config config = { };
    struct ad5398_chip_info *chip;
    const struct ad5398_current_data_format *df =
            (struct ad5398_current_data_format *)id->driver_data;
    int ret;

    if (!init_data)
        return -EINVAL;

    chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
    if (!chip)
        return -ENOMEM;

    config.dev = &client->dev;
    config.init_data = init_data;
    config.driver_data = chip;

    chip->client = client;

    chip->min_uA = df->min_uA;
    chip->max_uA = df->max_uA;
    chip->current_level = 1 << df->current_bits;
    chip->current_offset = df->current_offset;
    chip->current_mask = (chip->current_level - 1) << chip->current_offset;

    chip->rdev = regulator_register(&ad5398_reg, &config);
    if (IS_ERR(chip->rdev)) {
        ret = PTR_ERR(chip->rdev);
        dev_err(&client->dev, "failed to register %s %s\n",
            id->name, ad5398_reg.name);
        goto err;
    }

    i2c_set_clientdata(client, chip);
    dev_dbg(&client->dev, "%s regulator driver is registered.\n", id->name);
    return 0;

err:
    return ret;
}

static int __devexit ad5398_remove(struct i2c_client *client)
{
    struct ad5398_chip_info *chip = i2c_get_clientdata(client);

    regulator_unregister(chip->rdev);
    return 0;
}

static struct i2c_driver ad5398_driver = {
    .probe = ad5398_probe,
    .remove = __devexit_p(ad5398_remove),
    .driver     = {
        .name   = "ad5398",
    },
    .id_table   = ad5398_id,
};

static int __init ad5398_init(void)
{
    return i2c_add_driver(&ad5398_driver);
}
subsys_initcall(ad5398_init);

static void __exit ad5398_exit(void)
{
    i2c_del_driver(&ad5398_driver);
}
module_exit(ad5398_exit);

MODULE_DESCRIPTION("AD5398 and AD5821 current regulator driver");
MODULE_AUTHOR("Sonic Zhang");
MODULE_LICENSE("GPL");
MODULE_ALIAS("i2c:ad5398-regulator");