linux-imx

/*

 * drivers/pwm/pwm-pxa.c

 *

 * simple driver for PWM (Pulse Width Modulator) controller

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * 2008-02-13   initial version

 *      eric miao <eric.miao@marvell.com>

 */

​

#include <linux/module.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 <linux/of_device.h>

​

#include <asm/div64.h>

​

#define HAS_SECONDARY_PWM   0x10

​

static const struct platform_device_id pwm_id_table[] = {

    /*   PWM    has_secondary_pwm? */

    { "pxa25x-pwm", 0 },

    { "pxa27x-pwm", HAS_SECONDARY_PWM },

    { "pxa168-pwm", 0 },

    { "pxa910-pwm", 0 },

    { },

};

MODULE_DEVICE_TABLE(platform, pwm_id_table);

​

/* PWM registers and bits definitions */

#define PWMCR       (0x00)

#define PWMDCR      (0x04)

#define PWMPCR      (0x08)

​

#define PWMCR_SD    (1 << 6)

#define PWMDCR_FD   (1 << 10)

​

struct pxa_pwm_chip {

    struct pwm_chip chip;

    struct device   *dev;

​

    struct clk  *clk;

    void __iomem    *mmio_base;

};

​

static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)

{

    return container_of(chip, struct pxa_pwm_chip, chip);

}

​

/*

 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE

 * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE

 */

static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,

              int duty_ns, int period_ns)

{

    struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);

    unsigned long long c;

    unsigned long period_cycles, prescale, pv, dc;

    unsigned long offset;

    int rc;

​

    offset = pwm->hwpwm ? 0x10 : 0;

​

    c = clk_get_rate(pc->clk);

    c = c * period_ns;

    do_div(c, 1000000000);

    period_cycles = c;

​

    if (period_cycles < 1)

        period_cycles = 1;

    prescale = (period_cycles - 1) / 1024;

    pv = period_cycles / (prescale + 1) - 1;

​

    if (prescale > 63)

        return -EINVAL;

​

    if (duty_ns == period_ns)

        dc = PWMDCR_FD;

    else

        dc = (pv + 1) * duty_ns / period_ns;

​

    /* NOTE: the clock to PWM has to be enabled first