max8660.c

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/*
 * max8660.c  --  Voltage regulation for the Maxim 8660/8661
 *
 * based on max1586.c and wm8400-regulator.c
 *
 * Copyright (C) 2009 Wolfram Sang, Pengutronix e.K.
 *
 * 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; version 2 of the License.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Some info:
 *
 * Datasheet: http://datasheets.maxim-ic.com/en/ds/MAX8660-MAX8661.pdf
 *
 * This chip is a bit nasty because it is a write-only device. Thus, the driver
 * uses shadow registers to keep track of its values. The main problem appears
 * to be the initialization: When Linux boots up, we cannot know if the chip is
 * in the default state or not, so we would have to pass such information in
 * platform_data. As this adds a bit of complexity to the driver, this is left
 * out for now until it is really needed.
 *
 * [A|S|M]DTV1 registers are currently not used, but [A|S|M]DTV2.
 *
 * If the driver is feature complete, it might be worth to check if one set of
 * functions for V3-V7 is sufficient. For maximum flexibility during
 * development, they are separated for now.
 *
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/slab.h>
#include <linux/regulator/max8660.h>

#define MAX8660_DCDC_MIN_UV  725000
#define MAX8660_DCDC_MAX_UV 1800000
#define MAX8660_DCDC_STEP     25000
#define MAX8660_DCDC_MAX_SEL    0x2b

#define MAX8660_LDO5_MIN_UV 1700000
#define MAX8660_LDO5_MAX_UV 2000000
#define MAX8660_LDO5_STEP     25000
#define MAX8660_LDO5_MAX_SEL    0x0c

#define MAX8660_LDO67_MIN_UV    1800000
#define MAX8660_LDO67_MAX_UV    3300000
#define MAX8660_LDO67_STEP   100000
#define MAX8660_LDO67_MAX_SEL   0x0f

enum {
    MAX8660_OVER1,
    MAX8660_OVER2,
    MAX8660_VCC1,
    MAX8660_ADTV1,
    MAX8660_ADTV2,
    MAX8660_SDTV1,
    MAX8660_SDTV2,
    MAX8660_MDTV1,
    MAX8660_MDTV2,
    MAX8660_L12VCR,
    MAX8660_FPWM,
    MAX8660_N_REGS, /* not a real register */
};

struct max8660 {
    struct i2c_client *client;
    u8 shadow_regs[MAX8660_N_REGS];     /* as chip is write only */
    struct regulator_dev *rdev[];
};

static int max8660_write(struct max8660 *max8660, u8 reg, u8 mask, u8 val)
{
    static const u8 max8660_addresses[MAX8660_N_REGS] =
      { 0x10, 0x12, 0x20, 0x23, 0x24, 0x29, 0x2a, 0x32, 0x33, 0x39, 0x80 };

    int ret;
    u8 reg_val = (max8660->shadow_regs[reg] & mask) | val;
    dev_vdbg(&max8660->client->dev, "Writing reg %02x with %02x\n",
            max8660_addresses[reg], reg_val);

    ret = i2c_smbus_write_byte_data(max8660->client,
            max8660_addresses[reg], reg_val);
    if (ret == 0)
        max8660->shadow_regs[reg] = reg_val;

    return ret;
}


/*
 * DCDC functions
 */

static int max8660_dcdc_is_enabled(struct regulator_dev *rdev)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);
    u8 val = max8660->shadow_regs[MAX8660_OVER1];
    u8 mask = (rdev_get_id(rdev) == MAX8660_V3) ? 1 : 4;
    return !!(val & mask);
}

static int max8660_dcdc_enable(struct regulator_dev *rdev)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);
    u8 bit = (rdev_get_id(rdev) == MAX8660_V3) ? 1 : 4;
    return max8660_write(max8660, MAX8660_OVER1, 0xff, bit);
}

static int max8660_dcdc_disable(struct regulator_dev *rdev)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);
    u8 mask = (rdev_get_id(rdev) == MAX8660_V3) ? ~1 : ~4;
    return max8660_write(max8660, MAX8660_OVER1, mask, 0);
}

static int max8660_dcdc_get_voltage_sel(struct regulator_dev *rdev)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);

    u8 reg = (rdev_get_id(rdev) == MAX8660_V3) ? MAX8660_ADTV2 : MAX8660_SDTV2;
    u8 selector = max8660->shadow_regs[reg];
    return selector;
}

static int max8660_dcdc_set_voltage_sel(struct regulator_dev *rdev,
                    unsigned int selector)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);
    u8 reg, bits;
    int ret;

    reg = (rdev_get_id(rdev) == MAX8660_V3) ? MAX8660_ADTV2 : MAX8660_SDTV2;
    ret = max8660_write(max8660, reg, 0, selector);
    if (ret)
        return ret;

    /* Select target voltage register and activate regulation */
    bits = (rdev_get_id(rdev) == MAX8660_V3) ? 0x03 : 0x30;
    return max8660_write(max8660, MAX8660_VCC1, 0xff, bits);
}

static struct regulator_ops max8660_dcdc_ops = {
    .is_enabled = max8660_dcdc_is_enabled,
    .list_voltage = regulator_list_voltage_linear,
    .map_voltage = regulator_map_voltage_linear,
    .set_voltage_sel = max8660_dcdc_set_voltage_sel,
    .get_voltage_sel = max8660_dcdc_get_voltage_sel,
};


/*
 * LDO5 functions
 */

static int max8660_ldo5_get_voltage_sel(struct regulator_dev *rdev)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);

    u8 selector = max8660->shadow_regs[MAX8660_MDTV2];
    return selector;
}

static int max8660_ldo5_set_voltage_sel(struct regulator_dev *rdev,
                    unsigned int selector)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);
    int ret;

    ret = max8660_write(max8660, MAX8660_MDTV2, 0, selector);
    if (ret)
        return ret;

    /* Select target voltage register and activate regulation */
    return max8660_write(max8660, MAX8660_VCC1, 0xff, 0xc0);
}

static struct regulator_ops max8660_ldo5_ops = {
    .list_voltage = regulator_list_voltage_linear,
    .map_voltage = regulator_map_voltage_linear,
    .set_voltage_sel = max8660_ldo5_set_voltage_sel,
    .get_voltage_sel = max8660_ldo5_get_voltage_sel,
};


/*
 * LDO67 functions
 */

static int max8660_ldo67_is_enabled(struct regulator_dev *rdev)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);
    u8 val = max8660->shadow_regs[MAX8660_OVER2];
    u8 mask = (rdev_get_id(rdev) == MAX8660_V6) ? 2 : 4;
    return !!(val & mask);
}

static int max8660_ldo67_enable(struct regulator_dev *rdev)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);
    u8 bit = (rdev_get_id(rdev) == MAX8660_V6) ? 2 : 4;
    return max8660_write(max8660, MAX8660_OVER2, 0xff, bit);
}

static int max8660_ldo67_disable(struct regulator_dev *rdev)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);
    u8 mask = (rdev_get_id(rdev) == MAX8660_V6) ? ~2 : ~4;
    return max8660_write(max8660, MAX8660_OVER2, mask, 0);
}

static int max8660_ldo67_get_voltage_sel(struct regulator_dev *rdev)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);

    u8 shift = (rdev_get_id(rdev) == MAX8660_V6) ? 0 : 4;
    u8 selector = (max8660->shadow_regs[MAX8660_L12VCR] >> shift) & 0xf;
    return selector;
}

static int max8660_ldo67_set_voltage_sel(struct regulator_dev *rdev,
                     unsigned int selector)
{
    struct max8660 *max8660 = rdev_get_drvdata(rdev);

    if (rdev_get_id(rdev) == MAX8660_V6)
        return max8660_write(max8660, MAX8660_L12VCR, 0xf0, selector);
    else
        return max8660_write(max8660, MAX8660_L12VCR, 0x0f,
                     selector << 4);
}

static struct regulator_ops max8660_ldo67_ops = {
    .is_enabled = max8660_ldo67_is_enabled,
    .enable = max8660_ldo67_enable,
    .disable = max8660_ldo67_disable,
    .list_voltage = regulator_list_voltage_linear,
    .map_voltage = regulator_map_voltage_linear,
    .get_voltage_sel = max8660_ldo67_get_voltage_sel,
    .set_voltage_sel = max8660_ldo67_set_voltage_sel,
};

static const struct regulator_desc max8660_reg[] = {
    {
        .name = "V3(DCDC)",
        .id = MAX8660_V3,
        .ops = &max8660_dcdc_ops,
        .type = REGULATOR_VOLTAGE,
        .n_voltages = MAX8660_DCDC_MAX_SEL + 1,
        .owner = THIS_MODULE,
        .min_uV = MAX8660_DCDC_MIN_UV,
        .uV_step = MAX8660_DCDC_STEP,
    },
    {
        .name = "V4(DCDC)",
        .id = MAX8660_V4,
        .ops = &max8660_dcdc_ops,
        .type = REGULATOR_VOLTAGE,
        .n_voltages = MAX8660_DCDC_MAX_SEL + 1,
        .owner = THIS_MODULE,
        .min_uV = MAX8660_DCDC_MIN_UV,
        .uV_step = MAX8660_DCDC_STEP,
    },
    {
        .name = "V5(LDO)",
        .id = MAX8660_V5,
        .ops = &max8660_ldo5_ops,
        .type = REGULATOR_VOLTAGE,
        .n_voltages = MAX8660_LDO5_MAX_SEL + 1,
        .owner = THIS_MODULE,
        .min_uV = MAX8660_LDO5_MIN_UV,
        .uV_step = MAX8660_LDO5_STEP,
    },
    {
        .name = "V6(LDO)",
        .id = MAX8660_V6,
        .ops = &max8660_ldo67_ops,
        .type = REGULATOR_VOLTAGE,
        .n_voltages = MAX8660_LDO67_MAX_SEL + 1,
        .owner = THIS_MODULE,
        .min_uV = MAX8660_LDO67_MIN_UV,
        .uV_step = MAX8660_LDO67_STEP,
    },
    {
        .name = "V7(LDO)",
        .id = MAX8660_V7,
        .ops = &max8660_ldo67_ops,
        .type = REGULATOR_VOLTAGE,
        .n_voltages = MAX8660_LDO67_MAX_SEL + 1,
        .owner = THIS_MODULE,
        .min_uV = MAX8660_LDO67_MIN_UV,
        .uV_step = MAX8660_LDO67_STEP,
    },
};

static int __devinit max8660_probe(struct i2c_client *client,
                   const struct i2c_device_id *i2c_id)
{
    struct regulator_dev **rdev;
    struct max8660_platform_data *pdata = client->dev.platform_data;
    struct regulator_config config = { };
    struct max8660 *max8660;
    int boot_on, i, id, ret = -EINVAL;

    if (pdata->num_subdevs > MAX8660_V_END) {
        dev_err(&client->dev, "Too many regulators found!\n");
        return -EINVAL;
    }

    max8660 = devm_kzalloc(&client->dev, sizeof(struct max8660) +
            sizeof(struct regulator_dev *) * MAX8660_V_END,
            GFP_KERNEL);
    if (!max8660)
        return -ENOMEM;

    max8660->client = client;
    rdev = max8660->rdev;

    if (pdata->en34_is_high) {
        /* Simulate always on */
        max8660->shadow_regs[MAX8660_OVER1] = 5;
    } else {
        /* Otherwise devices can be toggled via software */
        max8660_dcdc_ops.enable = max8660_dcdc_enable;
        max8660_dcdc_ops.disable = max8660_dcdc_disable;
    }

    /*
     * First, set up shadow registers to prevent glitches. As some
     * registers are shared between regulators, everything must be properly
     * set up for all regulators in advance.
     */
    max8660->shadow_regs[MAX8660_ADTV1] =
        max8660->shadow_regs[MAX8660_ADTV2] =
        max8660->shadow_regs[MAX8660_SDTV1] =
        max8660->shadow_regs[MAX8660_SDTV2] = 0x1b;
    max8660->shadow_regs[MAX8660_MDTV1] =
        max8660->shadow_regs[MAX8660_MDTV2] = 0x04;

    for (i = 0; i < pdata->num_subdevs; i++) {

        if (!pdata->subdevs[i].platform_data)
            goto err_out;

        boot_on = pdata->subdevs[i].platform_data->constraints.boot_on;

        switch (pdata->subdevs[i].id) {
        case MAX8660_V3:
            if (boot_on)
                max8660->shadow_regs[MAX8660_OVER1] |= 1;
            break;

        case MAX8660_V4:
            if (boot_on)
                max8660->shadow_regs[MAX8660_OVER1] |= 4;
            break;

        case MAX8660_V5:
            break;

        case MAX8660_V6:
            if (boot_on)
                max8660->shadow_regs[MAX8660_OVER2] |= 2;
            break;

        case MAX8660_V7:
            if (!strcmp(i2c_id->name, "max8661")) {
                dev_err(&client->dev, "Regulator not on this chip!\n");
                goto err_out;
            }

            if (boot_on)
                max8660->shadow_regs[MAX8660_OVER2] |= 4;
            break;

        default:
            dev_err(&client->dev, "invalid regulator %s\n",
                 pdata->subdevs[i].name);
            goto err_out;
        }
    }

    /* Finally register devices */
    for (i = 0; i < pdata->num_subdevs; i++) {

        id = pdata->subdevs[i].id;

        config.dev = &client->dev;
        config.init_data = pdata->subdevs[i].platform_data;
        config.driver_data = max8660;

        rdev[i] = regulator_register(&max8660_reg[id], &config);
        if (IS_ERR(rdev[i])) {
            ret = PTR_ERR(rdev[i]);
            dev_err(&client->dev, "failed to register %s\n",
                max8660_reg[id].name);
            goto err_unregister;
        }
    }

    i2c_set_clientdata(client, max8660);
    return 0;

err_unregister:
    while (--i >= 0)
        regulator_unregister(rdev[i]);
err_out:
    return ret;
}

static int __devexit max8660_remove(struct i2c_client *client)
{
    struct max8660 *max8660 = i2c_get_clientdata(client);
    int i;

    for (i = 0; i < MAX8660_V_END; i++)
        if (max8660->rdev[i])
            regulator_unregister(max8660->rdev[i]);
    return 0;
}

static const struct i2c_device_id max8660_id[] = {
    { "max8660", 0 },
    { "max8661", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, max8660_id);

static struct i2c_driver max8660_driver = {
    .probe = max8660_probe,
    .remove = __devexit_p(max8660_remove),
    .driver     = {
        .name   = "max8660",
        .owner  = THIS_MODULE,
    },
    .id_table   = max8660_id,
};

static int __init max8660_init(void)
{
    return i2c_add_driver(&max8660_driver);
}
subsys_initcall(max8660_init);

static void __exit max8660_exit(void)
{
    i2c_del_driver(&max8660_driver);
}
module_exit(max8660_exit);

/* Module information */
MODULE_DESCRIPTION("MAXIM 8660/8661 voltage regulator driver");
MODULE_AUTHOR("Wolfram Sang");
MODULE_LICENSE("GPL v2");