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  * Author: Alan Cox <alan@linux.intel.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  */
  15
  16 #include <linux/io.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/pm_runtime.h>
  20 #include <linux/time.h>
  21
  22 #include "pwm-lpss.h"
  23
  24 #define PWM                             0x00000000
  25 #define PWM_ENABLE                      BIT(31)
  26 #define PWM_SW_UPDATE                   BIT(30)
  27 #define PWM_BASE_UNIT_SHIFT             8
  28 #define PWM_ON_TIME_DIV_MASK            0x000000ff
  29 #define PWM_DIVISION_CORRECTION         0x2
  30
  31 /* Size of each PWM register space if multiple */
  32 #define PWM_SIZE                        0x400
  33
  34 struct pwm_lpss_chip {
  35         struct pwm_chip chip;
  36         void __iomem *regs;
  37         const struct pwm_lpss_boardinfo *info;
  38 };
  39
  40 /* BayTrail */
  41 const struct pwm_lpss_boardinfo pwm_lpss_byt_info = {
  42         .clk_rate = 25000000,
  43         .npwm = 1,
  44         .base_unit_bits = 16,
  45 };
  46 EXPORT_SYMBOL_GPL(pwm_lpss_byt_info);
  47
  48 /* Braswell */
  49 const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
  50         .clk_rate = 19200000,
  51         .npwm = 1,
  52         .base_unit_bits = 16,
  53 };
  54 EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info);
  55
  56 /* Broxton */
  57 const struct pwm_lpss_boardinfo pwm_lpss_bxt_info = {
  58         .clk_rate = 19200000,
  59         .npwm = 4,
  60         .base_unit_bits = 22,
  61 };
  62 EXPORT_SYMBOL_GPL(pwm_lpss_bxt_info);
  63
  64 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
  65 {
  66         return container_of(chip, struct pwm_lpss_chip, chip);
  67 }
  68
  69 static inline u32 pwm_lpss_read(const struct pwm_device *pwm)
  70 {
  71         struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
  72
  73         return readl(lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
  74 }
  75
  76 static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value)
  77 {
  78         struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
  79
  80         writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
  81 }
  82
  83 static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
  84                            int duty_ns, int period_ns)
  85 {
  86         struct pwm_lpss_chip *lpwm = to_lpwm(chip);
  87         u8 on_time_div;
  88         unsigned long c, base_unit_range;
  89         unsigned long long base_unit, freq = NSEC_PER_SEC;
  90         u32 ctrl;
  91
  92         do_div(freq, period_ns);
  93
  94         /*
  95          * The equation is:
  96          * base_unit = ((freq / c) * base_unit_range) + correction
  97          */
  98         base_unit_range = BIT(lpwm->info->base_unit_bits);
  99         base_unit = freq * base_unit_range;
 100
 101         c = lpwm->info->clk_rate;
 102         if (!c)
 103                 return -EINVAL;
 104
 105         do_div(base_unit, c);
 106         base_unit += PWM_DIVISION_CORRECTION;
 107
 108         if (duty_ns <= 0)
 109                 duty_ns = 1;
 110         on_time_div = 255 - (255 * duty_ns / period_ns);
 111
 112         pm_runtime_get_sync(chip->dev);
 113
 114         ctrl = pwm_lpss_read(pwm);
 115         ctrl &= ~PWM_ON_TIME_DIV_MASK;
 116         ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT);
 117         base_unit &= (base_unit_range - 1);
 118         ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT;
 119         ctrl |= on_time_div;
 120         /* request PWM to update on next cycle */
 121         ctrl |= PWM_SW_UPDATE;
 122         pwm_lpss_write(pwm, ctrl);
 123
 124         pm_runtime_put(chip->dev);
 125
 126         return 0;
 127 }
 128
 129 static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 130 {
 131         pm_runtime_get_sync(chip->dev);
 132         pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE);
 133         return 0;
 134 }
 135
 136 static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 137 {
 138         pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
 139         pm_runtime_put(chip->dev);
 140 }
 141
 142 static const struct pwm_ops pwm_lpss_ops = {
 143         .config = pwm_lpss_config,
 144         .enable = pwm_lpss_enable,
 145         .disable = pwm_lpss_disable,
 146         .owner = THIS_MODULE,
 147 };
 148
 149 struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 150                                      const struct pwm_lpss_boardinfo *info)
 151 {
 152         struct pwm_lpss_chip *lpwm;
 153         int ret;
 154
 155         lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
 156         if (!lpwm)
 157                 return ERR_PTR(-ENOMEM);
 158
 159         lpwm->regs = devm_ioremap_resource(dev, r);
 160         if (IS_ERR(lpwm->regs))
 161                 return ERR_CAST(lpwm->regs);
 162
 163         lpwm->info = info;
 164         lpwm->chip.dev = dev;
 165         lpwm->chip.ops = &pwm_lpss_ops;
 166         lpwm->chip.base = -1;
 167         lpwm->chip.npwm = info->npwm;
 168
 169         ret = pwmchip_add(&lpwm->chip);
 170         if (ret) {
 171                 dev_err(dev, "failed to add PWM chip: %d\n", ret);
 172                 return ERR_PTR(ret);
 173         }
 174
 175         return lpwm;
 176 }
 177 EXPORT_SYMBOL_GPL(pwm_lpss_probe);
 178
 179 int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
 180 {
 181         return pwmchip_remove(&lpwm->chip);
 182 }
 183 EXPORT_SYMBOL_GPL(pwm_lpss_remove);
 184
 185 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
 186 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
 187 MODULE_LICENSE("GPL v2");