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 };
  31
  32 static 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  */
  41 static 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
  82 static 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
  89 static 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
  96 static 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
 103 static 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
 139 static 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
 146 static struct platform_driver puv3_pwm_driver = {
 147         .driver = {
 148                 .name = "PKUnity-v3-PWM",
 149         },
 150         .probe = pwm_probe,
 151         .remove = pwm_remove,
 152 };
 153 module_platform_driver(puv3_pwm_driver);
 154
 155 MODULE_LICENSE("GPL v2");