linux/drivers/pwm/pwm-puv3.c
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   1/*
   2 * linux/arch/unicore32/kernel/pwm.c
   3 *
   4 * Code specific to PKUnity SoC and UniCore ISA
   5 *
   6 *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
   7 *      Copyright (C) 2001-2010 Guan Xuetao
   8 *
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License version 2 as
  11 * published by the Free Software Foundation.
  12 */
  13
  14#include <linux/module.h>
  15#include <linux/kernel.h>
  16#include <linux/platform_device.h>
  17#include <linux/slab.h>
  18#include <linux/err.h>
  19#include <linux/clk.h>
  20#include <linux/io.h>
  21#include <linux/pwm.h>
  22
  23#include <asm/div64.h>
  24#include <mach/hardware.h>
  25
  26struct puv3_pwm_chip {
  27        struct pwm_chip chip;
  28        void __iomem *base;
  29        struct clk *clk;
  30        bool enabled;
  31};
  32
  33static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
  34{
  35        return container_of(chip, struct puv3_pwm_chip, chip);
  36}
  37
  38/*
  39 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
  40 * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
  41 */
  42static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  43                           int duty_ns, int period_ns)
  44{
  45        unsigned long period_cycles, prescale, pv, dc;
  46        struct puv3_pwm_chip *puv3 = to_puv3(chip);
  47        unsigned long long c;
  48
  49        c = clk_get_rate(puv3->clk);
  50        c = c * period_ns;
  51        do_div(c, 1000000000);
  52        period_cycles = c;
  53
  54        if (period_cycles < 1)
  55                period_cycles = 1;
  56
  57        prescale = (period_cycles - 1) / 1024;
  58        pv = period_cycles / (prescale + 1) - 1;
  59
  60        if (prescale > 63)
  61                return -EINVAL;
  62
  63        if (duty_ns == period_ns)
  64                dc = OST_PWMDCCR_FDCYCLE;
  65        else
  66                dc = (pv + 1) * duty_ns / period_ns;
  67
  68        /*
  69         * NOTE: the clock to PWM has to be enabled first
  70         * before writing to the registers
  71         */
  72        clk_prepare_enable(puv3->clk);
  73
  74        writel(prescale, puv3->base + OST_PWM_PWCR);
  75        writel(pv - dc, puv3->base + OST_PWM_DCCR);
  76        writel(pv, puv3->base + OST_PWM_PCR);
  77
  78        clk_disable_unprepare(puv3->clk);
  79
  80        return 0;
  81}
  82
  83static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  84{
  85        struct puv3_pwm_chip *puv3 = to_puv3(chip);
  86
  87        return clk_prepare_enable(puv3->clk);
  88}
  89
  90static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  91{
  92        struct puv3_pwm_chip *puv3 = to_puv3(chip);
  93
  94        clk_disable_unprepare(puv3->clk);
  95}
  96
  97static const struct pwm_ops puv3_pwm_ops = {
  98        .config = puv3_pwm_config,
  99        .enable = puv3_pwm_enable,
 100        .disable = puv3_pwm_disable,
 101        .owner = THIS_MODULE,
 102};
 103
 104static int pwm_probe(struct platform_device *pdev)
 105{
 106        struct puv3_pwm_chip *puv3;
 107        struct resource *r;
 108        int ret;
 109
 110        puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
 111        if (puv3 == NULL) {
 112                dev_err(&pdev->dev, "failed to allocate memory\n");
 113                return -ENOMEM;
 114        }
 115
 116        puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
 117        if (IS_ERR(puv3->clk))
 118                return PTR_ERR(puv3->clk);
 119
 120        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 121        if (r == NULL) {
 122                dev_err(&pdev->dev, "no memory resource defined\n");
 123                return -ENODEV;
 124        }
 125
 126        puv3->base = devm_ioremap_resource(&pdev->dev, r);
 127        if (IS_ERR(puv3->base))
 128                return PTR_ERR(puv3->base);
 129
 130        puv3->chip.dev = &pdev->dev;
 131        puv3->chip.ops = &puv3_pwm_ops;
 132        puv3->chip.base = -1;
 133        puv3->chip.npwm = 1;
 134
 135        ret = pwmchip_add(&puv3->chip);
 136        if (ret < 0) {
 137                dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 138                return ret;
 139        }
 140
 141        platform_set_drvdata(pdev, puv3);
 142        return 0;
 143}
 144
 145static int pwm_remove(struct platform_device *pdev)
 146{
 147        struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
 148
 149        return pwmchip_remove(&puv3->chip);
 150}
 151
 152static struct platform_driver puv3_pwm_driver = {
 153        .driver = {
 154                .name = "PKUnity-v3-PWM",
 155        },
 156        .probe = pwm_probe,
 157        .remove = pwm_remove,
 158};
 159module_platform_driver(puv3_pwm_driver);
 160
 161MODULE_LICENSE("GPL v2");
 162
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