pwm-ab8500.c

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/*
 * Copyright (C) ST-Ericsson SA 2010
 *
 * Author: Arun R Murthy <[email protected]>
 * License terms: GNU General Public License (GPL) version 2
 */
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/pwm.h>
#include <linux/mfd/abx500.h>
#include <linux/mfd/abx500/ab8500.h>
#include <linux/module.h>

/*
 * PWM Out generators
 * Bank: 0x10
 */
#define AB8500_PWM_OUT_CTRL1_REG    0x60
#define AB8500_PWM_OUT_CTRL2_REG    0x61
#define AB8500_PWM_OUT_CTRL7_REG    0x66

/* backlight driver constants */
#define ENABLE_PWM          1
#define DISABLE_PWM         0

struct ab8500_pwm_chip {
    struct pwm_chip chip;
};

static int ab8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                 int duty_ns, int period_ns)
{
    int ret = 0;
    unsigned int higher_val, lower_val;
    u8 reg;

    /*
     * get the first 8 bits that are be written to
     * AB8500_PWM_OUT_CTRL1_REG[0:7]
     */
    lower_val = duty_ns & 0x00FF;
    /*
     * get bits [9:10] that are to be written to
     * AB8500_PWM_OUT_CTRL2_REG[0:1]
     */
    higher_val = ((duty_ns & 0x0300) >> 8);

    reg = AB8500_PWM_OUT_CTRL1_REG + ((chip->base - 1) * 2);

    ret = abx500_set_register_interruptible(chip->dev, AB8500_MISC,
            reg, (u8)lower_val);
    if (ret < 0)
        return ret;
    ret = abx500_set_register_interruptible(chip->dev, AB8500_MISC,
            (reg + 1), (u8)higher_val);

    return ret;
}

static int ab8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    int ret;

    ret = abx500_mask_and_set_register_interruptible(chip->dev,
                AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
                1 << (chip->base - 1), ENABLE_PWM);
    if (ret < 0)
        dev_err(chip->dev, "%s: Failed to disable PWM, Error %d\n",
                            pwm->label, ret);
    return ret;
}

static void ab8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    int ret;

    ret = abx500_mask_and_set_register_interruptible(chip->dev,
                AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
                1 << (chip->base - 1), DISABLE_PWM);
    if (ret < 0)
        dev_err(chip->dev, "%s: Failed to disable PWM, Error %d\n",
                            pwm->label, ret);
    return;
}

static const struct pwm_ops ab8500_pwm_ops = {
    .config = ab8500_pwm_config,
    .enable = ab8500_pwm_enable,
    .disable = ab8500_pwm_disable,
};

static int __devinit ab8500_pwm_probe(struct platform_device *pdev)
{
    struct ab8500_pwm_chip *ab8500;
    int err;

    /*
     * Nothing to be done in probe, this is required to get the
     * device which is required for ab8500 read and write
     */
    ab8500 = kzalloc(sizeof(*ab8500), GFP_KERNEL);
    if (ab8500 == NULL) {
        dev_err(&pdev->dev, "failed to allocate memory\n");
        return -ENOMEM;
    }

    ab8500->chip.dev = &pdev->dev;
    ab8500->chip.ops = &ab8500_pwm_ops;
    ab8500->chip.base = pdev->id;
    ab8500->chip.npwm = 1;

    err = pwmchip_add(&ab8500->chip);
    if (err < 0) {
        kfree(ab8500);
        return err;
    }

    dev_dbg(&pdev->dev, "pwm probe successful\n");
    platform_set_drvdata(pdev, ab8500);

    return 0;
}

static int __devexit ab8500_pwm_remove(struct platform_device *pdev)
{
    struct ab8500_pwm_chip *ab8500 = platform_get_drvdata(pdev);
    int err;

    err = pwmchip_remove(&ab8500->chip);
    if (err < 0)
        return err;

    dev_dbg(&pdev->dev, "pwm driver removed\n");
    kfree(ab8500);

    return 0;
}

static struct platform_driver ab8500_pwm_driver = {
    .driver = {
        .name = "ab8500-pwm",
        .owner = THIS_MODULE,
    },
    .probe = ab8500_pwm_probe,
    .remove = __devexit_p(ab8500_pwm_remove),
};
module_platform_driver(ab8500_pwm_driver);

MODULE_AUTHOR("Arun MURTHY <[email protected]>");
MODULE_DESCRIPTION("AB8500 Pulse Width Modulation Driver");
MODULE_ALIAS("platform:ab8500-pwm");
MODULE_LICENSE("GPL v2");