drivers/pwm/pwm-puv3.c

   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
  26 struct puv3_pwm_chip {
  27         struct pwm_chip chip;
  28         void __iomem *base;
  29         struct clk *clk;
  30         bool enabled;
  31 };
  32
  33 static 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  */
  42 static 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
  83 static 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
  90 static 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
  97 static 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
 104 static 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
 145 static 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
 152 static struct platform_driver puv3_pwm_driver = {
 153         .driver = {
 154                 .name = "PKUnity-v3-PWM",
 155         },
 156         .probe = pwm_probe,
 157         .remove = pwm_remove,
 158 };
 159 module_platform_driver(puv3_pwm_driver);
 160
 161 MODULE_LICENSE("GPL v2");