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 <[email protected]>
   6  * Author: Chew Kean Ho <[email protected]>
   7  * Author: Chang Rebecca Swee Fun <[email protected]>
   8  * Author: Chew Chiau Ee <[email protected]>
   9  * Author: Alan Cox <[email protected]>
  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/delay.h>
  17 #include <linux/io.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/pm_runtime.h>
  21 #include <linux/time.h>
  22
  23 #include "pwm-lpss.h"
  24
  25 #define PWM                             0x00000000
  26 #define PWM_ENABLE                      BIT(31)
  27 #define PWM_SW_UPDATE                   BIT(30)
  28 #define PWM_BASE_UNIT_SHIFT             8
  29 #define PWM_ON_TIME_DIV_MASK            0x000000ff
  30 #define PWM_DIVISION_CORRECTION         0x2
  31
  32 /* Size of each PWM register space if multiple */
  33 #define PWM_SIZE                        0x400
  34
  35 struct pwm_lpss_chip {
  36         struct pwm_chip chip;
  37         void __iomem *regs;
  38         const struct pwm_lpss_boardinfo *info;
  39 };
  40
  41 /* BayTrail */
  42 const struct pwm_lpss_boardinfo pwm_lpss_byt_info = {
  43         .clk_rate = 25000000,
  44         .npwm = 1,
  45         .base_unit_bits = 16,
  46 };
  47 EXPORT_SYMBOL_GPL(pwm_lpss_byt_info);
  48
  49 /* Braswell */
  50 const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
  51         .clk_rate = 19200000,
  52         .npwm = 1,
  53         .base_unit_bits = 16,
  54 };
  55 EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info);
  56
  57 /* Broxton */
  58 const struct pwm_lpss_boardinfo pwm_lpss_bxt_info = {
  59         .clk_rate = 19200000,
  60         .npwm = 4,
  61         .base_unit_bits = 22,
  62 };
  63 EXPORT_SYMBOL_GPL(pwm_lpss_bxt_info);
  64
  65 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
  66 {
  67         return container_of(chip, struct pwm_lpss_chip, chip);
  68 }
  69
  70 static inline u32 pwm_lpss_read(const struct pwm_device *pwm)
  71 {
  72         struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
  73
  74         return readl(lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
  75 }
  76
  77 static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value)
  78 {
  79         struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
  80
  81         writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
  82 }
  83
  84 static void pwm_lpss_update(struct pwm_device *pwm)
  85 {
  86         pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_SW_UPDATE);
  87         /* Give it some time to propagate */
  88         usleep_range(10, 50);
  89 }
  90
  91 static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
  92                            int duty_ns, int period_ns)
  93 {
  94         struct pwm_lpss_chip *lpwm = to_lpwm(chip);
  95         u8 on_time_div;
  96         unsigned long c, base_unit_range;
  97         unsigned long long base_unit, freq = NSEC_PER_SEC;
  98         u32 ctrl;
  99
 100         do_div(freq, period_ns);
 101
 102         /*
 103          * The equation is:
 104          * base_unit = ((freq / c) * base_unit_range) + correction
 105          */
 106         base_unit_range = BIT(lpwm->info->base_unit_bits);
 107         base_unit = freq * base_unit_range;
 108
 109         c = lpwm->info->clk_rate;
 110         if (!c)
 111                 return -EINVAL;
 112
 113         do_div(base_unit, c);
 114         base_unit += PWM_DIVISION_CORRECTION;
 115
 116         if (duty_ns <= 0)
 117                 duty_ns = 1;
 118         on_time_div = 255 - (255 * duty_ns / period_ns);
 119
 120         pm_runtime_get_sync(chip->dev);
 121
 122         ctrl = pwm_lpss_read(pwm);
 123         ctrl &= ~PWM_ON_TIME_DIV_MASK;
 124         ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT);
 125         base_unit &= (base_unit_range - 1);
 126         ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT;
 127         ctrl |= on_time_div;
 128         pwm_lpss_write(pwm, ctrl);
 129
 130         /*
 131          * If the PWM is already enabled we need to notify the hardware
 132          * about the change by setting PWM_SW_UPDATE.
 133          */
 134         if (pwm_is_enabled(pwm))
 135                 pwm_lpss_update(pwm);
 136
 137         pm_runtime_put(chip->dev);
 138
 139         return 0;
 140 }
 141
 142 static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 143 {
 144         pm_runtime_get_sync(chip->dev);
 145
 146         /*
 147          * Hardware must first see PWM_SW_UPDATE before the PWM can be
 148          * enabled.
 149          */
 150         pwm_lpss_update(pwm);
 151         pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE);
 152         return 0;
 153 }
 154
 155 static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 156 {
 157         pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
 158         pm_runtime_put(chip->dev);
 159 }
 160
 161 static const struct pwm_ops pwm_lpss_ops = {
 162         .config = pwm_lpss_config,
 163         .enable = pwm_lpss_enable,
 164         .disable = pwm_lpss_disable,
 165         .owner = THIS_MODULE,
 166 };
 167
 168 struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 169                                      const struct pwm_lpss_boardinfo *info)
 170 {
 171         struct pwm_lpss_chip *lpwm;
 172         int ret;
 173
 174         lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
 175         if (!lpwm)
 176                 return ERR_PTR(-ENOMEM);
 177
 178         lpwm->regs = devm_ioremap_resource(dev, r);
 179         if (IS_ERR(lpwm->regs))
 180                 return ERR_CAST(lpwm->regs);
 181
 182         lpwm->info = info;
 183         lpwm->chip.dev = dev;
 184         lpwm->chip.ops = &pwm_lpss_ops;
 185         lpwm->chip.base = -1;
 186         lpwm->chip.npwm = info->npwm;
 187
 188         ret = pwmchip_add(&lpwm->chip);
 189         if (ret) {
 190                 dev_err(dev, "failed to add PWM chip: %d\n", ret);
 191                 return ERR_PTR(ret);
 192         }
 193
 194         return lpwm;
 195 }
 196 EXPORT_SYMBOL_GPL(pwm_lpss_probe);
 197
 198 int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
 199 {
 200         return pwmchip_remove(&lpwm->chip);
 201 }
 202 EXPORT_SYMBOL_GPL(pwm_lpss_remove);
 203
 204 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
 205 MODULE_AUTHOR("Mika Westerberg <[email protected]>");
 206 MODULE_LICENSE("GPL v2");