drivers/pwm/pwm-lpss.c

   1 /*
   2  * Intel Low Power Subsystem PWM controller driver
   3  *
   4  * Copyright (C) 2014, Intel Corporation
   5  * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
   6  * Author: Chew Kean Ho <kean.ho.chew@intel.com>
   7  * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
   8  * Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/acpi.h>
  16 #include <linux/clk.h>
  17 #include <linux/device.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/pwm.h>
  21 #include <linux/platform_device.h>
  22
  23 #define PWM                             0x00000000
  24 #define PWM_ENABLE                      BIT(31)
  25 #define PWM_SW_UPDATE                   BIT(30)
  26 #define PWM_BASE_UNIT_SHIFT             8
  27 #define PWM_BASE_UNIT_MASK              0x00ffff00
  28 #define PWM_ON_TIME_DIV_MASK            0x000000ff
  29 #define PWM_DIVISION_CORRECTION         0x2
  30 #define PWM_LIMIT                       (0x8000 + PWM_DIVISION_CORRECTION)
  31 #define NSECS_PER_SEC                   1000000000UL
  32
  33 struct pwm_lpss_chip {
  34         struct pwm_chip chip;
  35         void __iomem *regs;
  36         struct clk *clk;
  37 };
  38
  39 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
  40 {
  41         return container_of(chip, struct pwm_lpss_chip, chip);
  42 }
  43
  44 static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
  45                            int duty_ns, int period_ns)
  46 {
  47         struct pwm_lpss_chip *lpwm = to_lpwm(chip);
  48         u8 on_time_div;
  49         unsigned long c;
  50         unsigned long long base_unit, freq = NSECS_PER_SEC;
  51         u32 ctrl;
  52
  53         do_div(freq, period_ns);
  54
  55         /* The equation is: base_unit = ((freq / c) * 65536) + correction */
  56         base_unit = freq * 65536;
  57
  58         c = clk_get_rate(lpwm->clk);
  59         if (!c)
  60                 return -EINVAL;
  61
  62         do_div(base_unit, c);
  63         base_unit += PWM_DIVISION_CORRECTION;
  64         if (base_unit > PWM_LIMIT)
  65                 return -EINVAL;
  66
  67         if (duty_ns <= 0)
  68                 duty_ns = 1;
  69         on_time_div = 255 - (255 * duty_ns / period_ns);
  70
  71         ctrl = readl(lpwm->regs + PWM);
  72         ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
  73         ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
  74         ctrl |= on_time_div;
  75         /* request PWM to update on next cycle */
  76         ctrl |= PWM_SW_UPDATE;
  77         writel(ctrl, lpwm->regs + PWM);
  78
  79         return 0;
  80 }
  81
  82 static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  83 {
  84         struct pwm_lpss_chip *lpwm = to_lpwm(chip);
  85         u32 ctrl;
  86         int ret;
  87
  88         ret = clk_prepare_enable(lpwm->clk);
  89         if (ret)
  90                 return ret;
  91
  92         ctrl = readl(lpwm->regs + PWM);
  93         writel(ctrl | PWM_ENABLE, lpwm->regs + PWM);
  94
  95         return 0;
  96 }
  97
  98 static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  99 {
 100         struct pwm_lpss_chip *lpwm = to_lpwm(chip);
 101         u32 ctrl;
 102
 103         ctrl = readl(lpwm->regs + PWM);
 104         writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
 105
 106         clk_disable_unprepare(lpwm->clk);
 107 }
 108
 109 static const struct pwm_ops pwm_lpss_ops = {
 110         .config = pwm_lpss_config,
 111         .enable = pwm_lpss_enable,
 112         .disable = pwm_lpss_disable,
 113         .owner = THIS_MODULE,
 114 };
 115
 116 static const struct acpi_device_id pwm_lpss_acpi_match[] = {
 117         { "80860F09", 0 },
 118         { },
 119 };
 120 MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match);
 121
 122 static int pwm_lpss_probe(struct platform_device *pdev)
 123 {
 124         struct pwm_lpss_chip *lpwm;
 125         struct resource *r;
 126         int ret;
 127
 128         lpwm = devm_kzalloc(&pdev->dev, sizeof(*lpwm), GFP_KERNEL);
 129         if (!lpwm)
 130                 return -ENOMEM;
 131
 132         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 133
 134         lpwm->regs = devm_ioremap_resource(&pdev->dev, r);
 135         if (IS_ERR(lpwm->regs))
 136                 return PTR_ERR(lpwm->regs);
 137
 138         lpwm->clk = devm_clk_get(&pdev->dev, NULL);
 139         if (IS_ERR(lpwm->clk)) {
 140                 dev_err(&pdev->dev, "failed to get PWM clock\n");
 141                 return PTR_ERR(lpwm->clk);
 142         }
 143
 144         lpwm->chip.dev = &pdev->dev;
 145         lpwm->chip.ops = &pwm_lpss_ops;
 146         lpwm->chip.base = -1;
 147         lpwm->chip.npwm = 1;
 148
 149         ret = pwmchip_add(&lpwm->chip);
 150         if (ret) {
 151                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 152                 return ret;
 153         }
 154
 155         platform_set_drvdata(pdev, lpwm);
 156         return 0;
 157 }
 158
 159 static int pwm_lpss_remove(struct platform_device *pdev)
 160 {
 161         struct pwm_lpss_chip *lpwm = platform_get_drvdata(pdev);
 162         u32 ctrl;
 163
 164         ctrl = readl(lpwm->regs + PWM);
 165         writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
 166
 167         return pwmchip_remove(&lpwm->chip);
 168 }
 169
 170 static struct platform_driver pwm_lpss_driver = {
 171         .driver = {
 172                 .name = "pwm-lpss",
 173                 .acpi_match_table = pwm_lpss_acpi_match,
 174         },
 175         .probe = pwm_lpss_probe,
 176         .remove = pwm_lpss_remove,
 177 };
 178 module_platform_driver(pwm_lpss_driver);
 179
 180 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
 181 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
 182 MODULE_LICENSE("GPL v2");
 183 MODULE_ALIAS("platform:pwm-lpss");