pwm-samsung.c

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/* drivers/pwm/pwm-samsung.c
 *
 * Copyright (c) 2007 Ben Dooks
 * Copyright (c) 2008 Simtec Electronics
 *  Ben Dooks <[email protected]>, <[email protected]>
 *
 * S3C series PWM device core
 *
 * 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.
*/

#define pr_fmt(fmt) "pwm-samsung: " fmt

#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pwm.h>

#include <mach/map.h>

#include <plat/regs-timer.h>

struct s3c_chip {
    struct platform_device  *pdev;

    struct clk      *clk_div;
    struct clk      *clk;
    const char      *label;

    unsigned int         period_ns;
    unsigned int         duty_ns;

    unsigned char        tcon_base;
    unsigned char        pwm_id;
    struct pwm_chip      chip;
};

#define to_s3c_chip(chip)   container_of(chip, struct s3c_chip, chip)

#define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)

static struct clk *clk_scaler[2];

static inline int pwm_is_tdiv(struct s3c_chip *chip)
{
    return clk_get_parent(chip->clk) == chip->clk_div;
}

#define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
#define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
#define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
#define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))

static int s3c_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    struct s3c_chip *s3c = to_s3c_chip(chip);
    unsigned long flags;
    unsigned long tcon;

    local_irq_save(flags);

    tcon = __raw_readl(S3C2410_TCON);
    tcon |= pwm_tcon_start(s3c);
    __raw_writel(tcon, S3C2410_TCON);

    local_irq_restore(flags);

    return 0;
}

static void s3c_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    struct s3c_chip *s3c = to_s3c_chip(chip);
    unsigned long flags;
    unsigned long tcon;

    local_irq_save(flags);

    tcon = __raw_readl(S3C2410_TCON);
    tcon &= ~pwm_tcon_start(s3c);
    __raw_writel(tcon, S3C2410_TCON);

    local_irq_restore(flags);
}

static unsigned long pwm_calc_tin(struct s3c_chip *s3c, unsigned long freq)
{
    unsigned long tin_parent_rate;
    unsigned int div;

    tin_parent_rate = clk_get_rate(clk_get_parent(s3c->clk_div));
    pwm_dbg(s3c, "tin parent at %lu\n", tin_parent_rate);

    for (div = 2; div <= 16; div *= 2) {
        if ((tin_parent_rate / (div << 16)) < freq)
            return tin_parent_rate / div;
    }

    return tin_parent_rate / 16;
}

#define NS_IN_HZ (1000000000UL)

static int s3c_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
        int duty_ns, int period_ns)
{
    struct s3c_chip *s3c = to_s3c_chip(chip);
    unsigned long tin_rate;
    unsigned long tin_ns;
    unsigned long period;
    unsigned long flags;
    unsigned long tcon;
    unsigned long tcnt;
    long tcmp;

    /* We currently avoid using 64bit arithmetic by using the
     * fact that anything faster than 1Hz is easily representable
     * by 32bits. */

    if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
        return -ERANGE;

    if (period_ns == s3c->period_ns &&
        duty_ns == s3c->duty_ns)
        return 0;

    /* The TCMP and TCNT can be read without a lock, they're not
     * shared between the timers. */

    tcmp = __raw_readl(S3C2410_TCMPB(s3c->pwm_id));
    tcnt = __raw_readl(S3C2410_TCNTB(s3c->pwm_id));

    period = NS_IN_HZ / period_ns;

    pwm_dbg(s3c, "duty_ns=%d, period_ns=%d (%lu)\n",
        duty_ns, period_ns, period);

    /* Check to see if we are changing the clock rate of the PWM */

    if (s3c->period_ns != period_ns) {
        if (pwm_is_tdiv(s3c)) {
            tin_rate = pwm_calc_tin(s3c, period);
            clk_set_rate(s3c->clk_div, tin_rate);
        } else
            tin_rate = clk_get_rate(s3c->clk);

        s3c->period_ns = period_ns;

        pwm_dbg(s3c, "tin_rate=%lu\n", tin_rate);

        tin_ns = NS_IN_HZ / tin_rate;
        tcnt = period_ns / tin_ns;
    } else
        tin_ns = NS_IN_HZ / clk_get_rate(s3c->clk);

    /* Note, counters count down */

    tcmp = duty_ns / tin_ns;
    tcmp = tcnt - tcmp;
    /* the pwm hw only checks the compare register after a decrement,
       so the pin never toggles if tcmp = tcnt */
    if (tcmp == tcnt)
        tcmp--;

    pwm_dbg(s3c, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);

    if (tcmp < 0)
        tcmp = 0;

    /* Update the PWM register block. */

    local_irq_save(flags);

    __raw_writel(tcmp, S3C2410_TCMPB(s3c->pwm_id));
    __raw_writel(tcnt, S3C2410_TCNTB(s3c->pwm_id));

    tcon = __raw_readl(S3C2410_TCON);
    tcon |= pwm_tcon_manulupdate(s3c);
    tcon |= pwm_tcon_autoreload(s3c);
    __raw_writel(tcon, S3C2410_TCON);

    tcon &= ~pwm_tcon_manulupdate(s3c);
    __raw_writel(tcon, S3C2410_TCON);

    local_irq_restore(flags);

    return 0;
}

static struct pwm_ops s3c_pwm_ops = {
    .enable = s3c_pwm_enable,
    .disable = s3c_pwm_disable,
    .config = s3c_pwm_config,
    .owner = THIS_MODULE,
};

static int s3c_pwm_probe(struct platform_device *pdev)
{
    struct device *dev = &pdev->dev;
    struct s3c_chip *s3c;
    unsigned long flags;
    unsigned long tcon;
    unsigned int id = pdev->id;
    int ret;

    if (id == 4) {
        dev_err(dev, "TIMER4 is currently not supported\n");
        return -ENXIO;
    }

    s3c = devm_kzalloc(&pdev->dev, sizeof(*s3c), GFP_KERNEL);
    if (s3c == NULL) {
        dev_err(dev, "failed to allocate pwm_device\n");
        return -ENOMEM;
    }

    /* calculate base of control bits in TCON */
    s3c->tcon_base = id == 0 ? 0 : (id * 4) + 4;
    s3c->chip.dev = &pdev->dev;
    s3c->chip.ops = &s3c_pwm_ops;
    s3c->chip.base = -1;
    s3c->chip.npwm = 1;

    s3c->clk = devm_clk_get(dev, "pwm-tin");
    if (IS_ERR(s3c->clk)) {
        dev_err(dev, "failed to get pwm tin clk\n");
        return PTR_ERR(s3c->clk);
    }

    s3c->clk_div = devm_clk_get(dev, "pwm-tdiv");
    if (IS_ERR(s3c->clk_div)) {
        dev_err(dev, "failed to get pwm tdiv clk\n");
        return PTR_ERR(s3c->clk_div);
    }

    clk_enable(s3c->clk);
    clk_enable(s3c->clk_div);

    local_irq_save(flags);

    tcon = __raw_readl(S3C2410_TCON);
    tcon |= pwm_tcon_invert(s3c);
    __raw_writel(tcon, S3C2410_TCON);

    local_irq_restore(flags);

    ret = pwmchip_add(&s3c->chip);
    if (ret < 0) {
        dev_err(dev, "failed to register pwm\n");
        goto err_clk_tdiv;
    }

    pwm_dbg(s3c, "config bits %02x\n",
        (__raw_readl(S3C2410_TCON) >> s3c->tcon_base) & 0x0f);

    dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
         clk_get_rate(s3c->clk),
         clk_get_rate(s3c->clk_div),
         pwm_is_tdiv(s3c) ? "div" : "ext", s3c->tcon_base);

    platform_set_drvdata(pdev, s3c);
    return 0;

 err_clk_tdiv:
    clk_disable(s3c->clk_div);
    clk_disable(s3c->clk);
    return ret;
}

static int __devexit s3c_pwm_remove(struct platform_device *pdev)
{
    struct s3c_chip *s3c = platform_get_drvdata(pdev);
    int err;

    err = pwmchip_remove(&s3c->chip);
    if (err < 0)
        return err;

    clk_disable(s3c->clk_div);
    clk_disable(s3c->clk);

    return 0;
}

#ifdef CONFIG_PM
static int s3c_pwm_suspend(struct platform_device *pdev, pm_message_t state)
{
    struct s3c_chip *s3c = platform_get_drvdata(pdev);

    /* No one preserve these values during suspend so reset them
     * Otherwise driver leaves PWM unconfigured if same values
     * passed to pwm_config
     */
    s3c->period_ns = 0;
    s3c->duty_ns = 0;

    return 0;
}

static int s3c_pwm_resume(struct platform_device *pdev)
{
    struct s3c_chip *s3c = platform_get_drvdata(pdev);
    unsigned long tcon;

    /* Restore invertion */
    tcon = __raw_readl(S3C2410_TCON);
    tcon |= pwm_tcon_invert(s3c);
    __raw_writel(tcon, S3C2410_TCON);

    return 0;
}

#else
#define s3c_pwm_suspend NULL
#define s3c_pwm_resume NULL
#endif

static struct platform_driver s3c_pwm_driver = {
    .driver     = {
        .name   = "s3c24xx-pwm",
        .owner  = THIS_MODULE,
    },
    .probe      = s3c_pwm_probe,
    .remove     = __devexit_p(s3c_pwm_remove),
    .suspend    = s3c_pwm_suspend,
    .resume     = s3c_pwm_resume,
};

static int __init pwm_init(void)
{
    int ret;

    clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
    clk_scaler[1] = clk_get(NULL, "pwm-scaler1");

    if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
        pr_err("failed to get scaler clocks\n");
        return -EINVAL;
    }

    ret = platform_driver_register(&s3c_pwm_driver);
    if (ret)
        pr_err("failed to add pwm driver\n");

    return ret;
}

arch_initcall(pwm_init);