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};
  31
  32static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
  33{
  34        return container_of(chip, struct puv3_pwm_chip, chip);
  35}
  36
  37/*
  38 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
  39 * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
  40 */
  41static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  42                           int duty_ns, int period_ns)
  43{
  44        unsigned long period_cycles, prescale, pv, dc;
  45        struct puv3_pwm_chip *puv3 = to_puv3(chip);
  46        unsigned long long c;
  47
  48        c = clk_get_rate(puv3->clk);
  49        c = c * period_ns;
  50        do_div(c, 1000000000);
  51        period_cycles = c;
  52
  53        if (period_cycles < 1)
  54                period_cycles = 1;
  55
  56        prescale = (period_cycles - 1) / 1024;
  57        pv = period_cycles / (prescale + 1) - 1;
  58
  59        if (prescale > 63)
  60                return -EINVAL;
  61
  62        if (duty_ns == period_ns)
  63                dc = OST_PWMDCCR_FDCYCLE;
  64        else
  65                dc = (pv + 1) * duty_ns / period_ns;
  66
  67        /*
  68         * NOTE: the clock to PWM has to be enabled first
  69         * before writing to the registers
  70         */
  71        clk_prepare_enable(puv3->clk);
  72
  73        writel(prescale, puv3->base + OST_PWM_PWCR);
  74        writel(pv - dc, puv3->base + OST_PWM_DCCR);
  75        writel(pv, puv3->base + OST_PWM_PCR);
  76
  77        clk_disable_unprepare(puv3->clk);
  78
  79        return 0;
  80}
  81
  82static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  83{
  84        struct puv3_pwm_chip *puv3 = to_puv3(chip);
  85
  86        return clk_prepare_enable(puv3->clk);
  87}
  88
  89static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  90{
  91        struct puv3_pwm_chip *puv3 = to_puv3(chip);
  92
  93        clk_disable_unprepare(puv3->clk);
  94}
  95
  96static const struct pwm_ops puv3_pwm_ops = {
  97        .config = puv3_pwm_config,
  98        .enable = puv3_pwm_enable,
  99        .disable = puv3_pwm_disable,
 100        .owner = THIS_MODULE,
 101};
 102
 103static int pwm_probe(struct platform_device *pdev)
 104{
 105        struct puv3_pwm_chip *puv3;
 106        struct resource *r;
 107        int ret;
 108
 109        puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
 110        if (puv3 == NULL) {
 111                dev_err(&pdev->dev, "failed to allocate memory\n");
 112                return -ENOMEM;
 113        }
 114
 115        puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
 116        if (IS_ERR(puv3->clk))
 117                return PTR_ERR(puv3->clk);
 118
 119        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 120        puv3->base = devm_ioremap_resource(&pdev->dev, r);
 121        if (IS_ERR(puv3->base))
 122                return PTR_ERR(puv3->base);
 123
 124        puv3->chip.dev = &pdev->dev;
 125        puv3->chip.ops = &puv3_pwm_ops;
 126        puv3->chip.base = -1;
 127        puv3->chip.npwm = 1;
 128
 129        ret = pwmchip_add(&puv3->chip);
 130        if (ret < 0) {
 131                dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 132                return ret;
 133        }
 134
 135        platform_set_drvdata(pdev, puv3);
 136        return 0;
 137}
 138
 139static int pwm_remove(struct platform_device *pdev)
 140{
 141        struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
 142
 143        return pwmchip_remove(&puv3->chip);
 144}
 145
 146static struct platform_driver puv3_pwm_driver = {
 147        .driver = {
 148                .name = "PKUnity-v3-PWM",
 149                .owner = THIS_MODULE,
 150        },
 151        .probe = pwm_probe,
 152        .remove = pwm_remove,
 153};
 154module_platform_driver(puv3_pwm_driver);
 155
 156MODULE_LICENSE("GPL v2");
 157
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