linux-imx

/*

 * Copyright 2012 Alexandre Pereira da Silva <aletes.xgr@gmail.com>

 *

 * 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.

 *

 */

​

#include <linux/clk.h>

#include <linux/err.h>

#include <linux/io.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/platform_device.h>

#include <linux/pwm.h>

#include <linux/slab.h>

​

struct lpc32xx_pwm_chip {

    struct pwm_chip chip;

    struct clk *clk;

    void __iomem *base;

};

​

#define PWM_ENABLE  BIT(31)

#define PWM_PIN_LEVEL   BIT(30)

​

#define to_lpc32xx_pwm_chip(_chip) \

    container_of(_chip, struct lpc32xx_pwm_chip, chip)

​

static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,

                  int duty_ns, int period_ns)

{

    struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);

    unsigned long long c;

    int period_cycles, duty_cycles;

    u32 val;

    c = clk_get_rate(lpc32xx->clk);

​

    /* The highest acceptable divisor is 256, which is represented by 0 */

    period_cycles = div64_u64(c * period_ns,

                   (unsigned long long)NSEC_PER_SEC * 256);

    if (!period_cycles || period_cycles > 256)

        return -ERANGE;

    if (period_cycles == 256)

        period_cycles = 0;

​

    /* Compute 256 x #duty/period value and care for corner cases */

    duty_cycles = div64_u64((unsigned long long)(period_ns - duty_ns) * 256,

                period_ns);

    if (!duty_cycles)

        duty_cycles = 1;

    if (duty_cycles > 255)

        duty_cycles = 255;

​

    val = readl(lpc32xx->base + (pwm->hwpwm << 2));

    val &= ~0xFFFF;

    val |= (period_cycles << 8) | duty_cycles;

    writel(val, lpc32xx->base + (pwm->hwpwm << 2));

​

    return 0;