pwm-bfin.c

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/*
 * Blackfin Pulse Width Modulation (PWM) core
 *
 * Copyright (c) 2011 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>

#include <asm/gptimers.h>
#include <asm/portmux.h>

struct bfin_pwm_chip {
    struct pwm_chip chip;
};

struct bfin_pwm {
    unsigned short pin;
};

static const unsigned short pwm_to_gptimer_per[] = {
    P_TMR0, P_TMR1, P_TMR2, P_TMR3, P_TMR4, P_TMR5,
    P_TMR6, P_TMR7, P_TMR8, P_TMR9, P_TMR10, P_TMR11,
};

static int bfin_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
    struct bfin_pwm *priv;
    int ret;

    if (pwm->hwpwm >= ARRAY_SIZE(pwm_to_gptimer_per))
        return -EINVAL;

    priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    if (!priv)
        return -ENOMEM;

    priv->pin = pwm_to_gptimer_per[pwm->hwpwm];

    ret = peripheral_request(priv->pin, NULL);
    if (ret) {
        kfree(priv);
        return ret;
    }

    pwm_set_chip_data(pwm, priv);

    return 0;
}

static void bfin_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
    struct bfin_pwm *priv = pwm_get_chip_data(pwm);

    if (priv) {
        peripheral_free(priv->pin);
        kfree(priv);
    }
}

static int bfin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
        int duty_ns, int period_ns)
{
    struct bfin_pwm *priv = pwm_get_chip_data(pwm);
    unsigned long period, duty;
    unsigned long long val;

    val = (unsigned long long)get_sclk() * period_ns;
    do_div(val, NSEC_PER_SEC);
    period = val;

    val = (unsigned long long)period * duty_ns;
    do_div(val, period_ns);
    duty = period - val;

    if (duty >= period)
        duty = period - 1;

    set_gptimer_config(priv->pin, TIMER_MODE_PWM | TIMER_PERIOD_CNT);
    set_gptimer_pwidth(priv->pin, duty);
    set_gptimer_period(priv->pin, period);

    return 0;
}

static int bfin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    struct bfin_pwm *priv = pwm_get_chip_data(pwm);

    enable_gptimer(priv->pin);

    return 0;
}

static void bfin_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    struct bfin_pwm *priv = pwm_get_chip_data(pwm);

    disable_gptimer(priv->pin);
}

static struct pwm_ops bfin_pwm_ops = {
    .request = bfin_pwm_request,
    .free = bfin_pwm_free,
    .config = bfin_pwm_config,
    .enable = bfin_pwm_enable,
    .disable = bfin_pwm_disable,
    .owner = THIS_MODULE,
};

static int bfin_pwm_probe(struct platform_device *pdev)
{
    struct bfin_pwm_chip *pwm;
    int ret;

    pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
    if (!pwm) {
        dev_err(&pdev->dev, "failed to allocate memory\n");
        return -ENOMEM;
    }

    platform_set_drvdata(pdev, pwm);

    pwm->chip.dev = &pdev->dev;
    pwm->chip.ops = &bfin_pwm_ops;
    pwm->chip.base = -1;
    pwm->chip.npwm = 12;

    ret = pwmchip_add(&pwm->chip);
    if (ret < 0) {
        dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
        return ret;
    }

    return 0;
}

static int __devexit bfin_pwm_remove(struct platform_device *pdev)
{
    struct bfin_pwm_chip *pwm = platform_get_drvdata(pdev);

    return pwmchip_remove(&pwm->chip);
}

static struct platform_driver bfin_pwm_driver = {
    .driver = {
        .name = "bfin-pwm",
    },
    .probe = bfin_pwm_probe,
    .remove = __devexit_p(bfin_pwm_remove),
};

module_platform_driver(bfin_pwm_driver);

MODULE_LICENSE("GPL");