2 * Intel Low Power Subsystem PWM controller driver
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>
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.
17 #include <linux/kernel.h>
18 #include <linux/module.h>
22 #define PWM 0x00000000
23 #define PWM_ENABLE BIT(31)
24 #define PWM_SW_UPDATE BIT(30)
25 #define PWM_BASE_UNIT_SHIFT 8
26 #define PWM_BASE_UNIT_MASK 0x00ffff00
27 #define PWM_ON_TIME_DIV_MASK 0x000000ff
28 #define PWM_DIVISION_CORRECTION 0x2
29 #define PWM_LIMIT (0x8000 + PWM_DIVISION_CORRECTION)
30 #define NSECS_PER_SEC 1000000000UL
32 /* Size of each PWM register space if multiple */
33 #define PWM_SIZE 0x400
35 struct pwm_lpss_chip {
38 unsigned long clk_rate;
42 const struct pwm_lpss_boardinfo pwm_lpss_byt_info = {
46 EXPORT_SYMBOL_GPL(pwm_lpss_byt_info);
49 const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
53 EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info);
56 const struct pwm_lpss_boardinfo pwm_lpss_bxt_info = {
60 EXPORT_SYMBOL_GPL(pwm_lpss_bxt_info);
62 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
64 return container_of(chip, struct pwm_lpss_chip, chip);
67 static inline u32 pwm_lpss_read(const struct pwm_device *pwm)
69 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
71 return readl(lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
74 static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value)
76 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
78 writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
81 static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
82 int duty_ns, int period_ns)
84 struct pwm_lpss_chip *lpwm = to_lpwm(chip);
87 unsigned long long base_unit, freq = NSECS_PER_SEC;
90 do_div(freq, period_ns);
92 /* The equation is: base_unit = ((freq / c) * 65536) + correction */
93 base_unit = freq * 65536;
100 base_unit += PWM_DIVISION_CORRECTION;
101 if (base_unit > PWM_LIMIT)
106 on_time_div = 255 - (255 * duty_ns / period_ns);
108 ctrl = pwm_lpss_read(pwm);
109 ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
110 ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
112 /* request PWM to update on next cycle */
113 ctrl |= PWM_SW_UPDATE;
114 pwm_lpss_write(pwm, ctrl);
119 static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
121 pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE);
125 static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
127 pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
130 static const struct pwm_ops pwm_lpss_ops = {
131 .free = pwm_lpss_disable,
132 .config = pwm_lpss_config,
133 .enable = pwm_lpss_enable,
134 .disable = pwm_lpss_disable,
135 .owner = THIS_MODULE,
138 struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
139 const struct pwm_lpss_boardinfo *info)
141 struct pwm_lpss_chip *lpwm;
144 lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
146 return ERR_PTR(-ENOMEM);
148 lpwm->regs = devm_ioremap_resource(dev, r);
149 if (IS_ERR(lpwm->regs))
150 return ERR_CAST(lpwm->regs);
152 lpwm->clk_rate = info->clk_rate;
153 lpwm->chip.dev = dev;
154 lpwm->chip.ops = &pwm_lpss_ops;
155 lpwm->chip.base = -1;
156 lpwm->chip.npwm = info->npwm;
158 ret = pwmchip_add(&lpwm->chip);
160 dev_err(dev, "failed to add PWM chip: %d\n", ret);
166 EXPORT_SYMBOL_GPL(pwm_lpss_probe);
168 int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
170 return pwmchip_remove(&lpwm->chip);
172 EXPORT_SYMBOL_GPL(pwm_lpss_remove);
174 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
175 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
176 MODULE_LICENSE("GPL v2");