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
  23 struct puv3_pwm_chip {
  24         struct pwm_chip chip;
  25         void __iomem *base;
  26         struct clk *clk;
  27 };
  28
  29 static 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  */
  38 static 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
  79 static 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
  86 static 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
  93 static 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
 100 static 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
 134 static 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
 141 static struct platform_driver puv3_pwm_driver = {
 142         .driver = {
 143                 .name = "PKUnity-v3-PWM",
 144         },
 145         .probe = pwm_probe,
 146         .remove = pwm_remove,
 147 };
 148 module_platform_driver(puv3_pwm_driver);
 149
 150 MODULE_LICENSE("GPL v2");