LXR linux/drivers/pwm/pwm-puv3.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * linux/arch/unicore32/kernel/pwm.c
   4 *
   5 * Code specific to PKUnity SoC and UniCore ISA
   6 *
   7 *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
   8 *      Copyright (C) 2001-2010 Guan Xuetao
   9 */
  10
  11#include <linux/module.h>
  12#include <linux/kernel.h>
  13#include <linux/platform_device.h>
  14#include <linux/slab.h>
  15#include <linux/err.h>
  16#include <linux/clk.h>
  17#include <linux/io.h>
  18#include <linux/pwm.h>
  19
  20#include <asm/div64.h>
  21#include <mach/hardware.h>
  22
  23struct puv3_pwm_chip {
  24        struct pwm_chip chip;
  25        void __iomem *base;
  26        struct clk *clk;
  27};
  28
  29static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
  30{
  31        return container_of(chip, struct puv3_pwm_chip, chip);
  32}
  33
  34/*
  35 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
  36 * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
  37 */
  38static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  39                           int duty_ns, int period_ns)
  40{
  41        unsigned long period_cycles, prescale, pv, dc;
  42        struct puv3_pwm_chip *puv3 = to_puv3(chip);
  43        unsigned long long c;
  44
  45        c = clk_get_rate(puv3->clk);
  46        c = c * period_ns;
  47        do_div(c, 1000000000);
  48        period_cycles = c;
  49
  50        if (period_cycles < 1)
  51                period_cycles = 1;
  52
  53        prescale = (period_cycles - 1) / 1024;
  54        pv = period_cycles / (prescale + 1) - 1;
  55
  56        if (prescale > 63)
  57                return -EINVAL;
  58
  59        if (duty_ns == period_ns)
  60                dc = OST_PWMDCCR_FDCYCLE;
  61        else
  62                dc = (pv + 1) * duty_ns / period_ns;
  63
  64        /*
  65         * NOTE: the clock to PWM has to be enabled first
  66         * before writing to the registers
  67         */
  68        clk_prepare_enable(puv3->clk);
  69
  70        writel(prescale, puv3->base + OST_PWM_PWCR);
  71        writel(pv - dc, puv3->base + OST_PWM_DCCR);
  72        writel(pv, puv3->base + OST_PWM_PCR);
  73
  74        clk_disable_unprepare(puv3->clk);
  75
  76        return 0;
  77}
  78
  79static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  80{
  81        struct puv3_pwm_chip *puv3 = to_puv3(chip);
  82
  83        return clk_prepare_enable(puv3->clk);
  84}
  85
  86static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  87{
  88        struct puv3_pwm_chip *puv3 = to_puv3(chip);
  89
  90        clk_disable_unprepare(puv3->clk);
  91}
  92
  93static const struct pwm_ops puv3_pwm_ops = {
  94        .config = puv3_pwm_config,
  95        .enable = puv3_pwm_enable,
  96        .disable = puv3_pwm_disable,
  97        .owner = THIS_MODULE,
  98};
  99
 100static int pwm_probe(struct platform_device *pdev)
 101{
 102        struct puv3_pwm_chip *puv3;
 103        struct resource *r;
 104        int ret;
 105
 106        puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
 107        if (!puv3)
 108                return -ENOMEM;
 109
 110        puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
 111        if (IS_ERR(puv3->clk))
 112                return PTR_ERR(puv3->clk);
 113
 114        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 115        puv3->base = devm_ioremap_resource(&pdev->dev, r);
 116        if (IS_ERR(puv3->base))
 117                return PTR_ERR(puv3->base);
 118
 119        puv3->chip.dev = &pdev->dev;
 120        puv3->chip.ops = &puv3_pwm_ops;
 121        puv3->chip.base = -1;
 122        puv3->chip.npwm = 1;
 123
 124        ret = pwmchip_add(&puv3->chip);
 125        if (ret < 0) {
 126                dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 127                return ret;
 128        }
 129
 130        platform_set_drvdata(pdev, puv3);
 131        return 0;
 132}
 133
 134static int pwm_remove(struct platform_device *pdev)
 135{
 136        struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
 137
 138        return pwmchip_remove(&puv3->chip);
 139}
 140
 141static struct platform_driver puv3_pwm_driver = {
 142        .driver = {
 143                .name = "PKUnity-v3-PWM",
 144        },
 145        .probe = pwm_probe,
 146        .remove = pwm_remove,
 147};
 148module_platform_driver(puv3_pwm_driver);
 149
 150MODULE_LICENSE("GPL v2");
 151