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);
55 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
57 return container_of(chip, struct pwm_lpss_chip, chip);
60 static inline u32 pwm_lpss_read(const struct pwm_device *pwm)
62 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
64 return readl(lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
67 static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value)
69 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
71 writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
74 static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
75 int duty_ns, int period_ns)
77 struct pwm_lpss_chip *lpwm = to_lpwm(chip);
80 unsigned long long base_unit, freq = NSECS_PER_SEC;
83 do_div(freq, period_ns);
85 /* The equation is: base_unit = ((freq / c) * 65536) + correction */
86 base_unit = freq * 65536;
93 base_unit += PWM_DIVISION_CORRECTION;
94 if (base_unit > PWM_LIMIT)
99 on_time_div = 255 - (255 * duty_ns / period_ns);
101 ctrl = pwm_lpss_read(pwm);
102 ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
103 ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
105 /* request PWM to update on next cycle */
106 ctrl |= PWM_SW_UPDATE;
107 pwm_lpss_write(pwm, ctrl);
112 static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
114 pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE);
118 static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
120 pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
123 static const struct pwm_ops pwm_lpss_ops = {
124 .free = pwm_lpss_disable,
125 .config = pwm_lpss_config,
126 .enable = pwm_lpss_enable,
127 .disable = pwm_lpss_disable,
128 .owner = THIS_MODULE,
131 struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
132 const struct pwm_lpss_boardinfo *info)
134 struct pwm_lpss_chip *lpwm;
137 lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
139 return ERR_PTR(-ENOMEM);
141 lpwm->regs = devm_ioremap_resource(dev, r);
142 if (IS_ERR(lpwm->regs))
143 return ERR_CAST(lpwm->regs);
145 lpwm->clk_rate = info->clk_rate;
146 lpwm->chip.dev = dev;
147 lpwm->chip.ops = &pwm_lpss_ops;
148 lpwm->chip.base = -1;
149 lpwm->chip.npwm = info->npwm;
151 ret = pwmchip_add(&lpwm->chip);
153 dev_err(dev, "failed to add PWM chip: %d\n", ret);
159 EXPORT_SYMBOL_GPL(pwm_lpss_probe);
161 int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
163 return pwmchip_remove(&lpwm->chip);
165 EXPORT_SYMBOL_GPL(pwm_lpss_remove);
167 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
168 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
169 MODULE_LICENSE("GPL v2");