drivers/pwm/pwm-lpss.c - linux - Git at Google

 /*
  * Intel Low Power Subsystem PWM controller driver
  *
  * Copyright (C) 2014, Intel Corporation
  * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
  * Author: Chew Kean Ho <kean.ho.chew@intel.com>
  * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
  * Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
  * Author: Alan Cox <alan@linux.intel.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
 #include <linux/time.h>

 #include "pwm-lpss.h"

 #define PWM				0x00000000
 #define PWM_ENABLE			BIT(31)
 #define PWM_SW_UPDATE			BIT(30)
 #define PWM_BASE_UNIT_SHIFT		8
 #define PWM_ON_TIME_DIV_MASK		0x000000ff

 /* Size of each PWM register space if multiple */
 #define PWM_SIZE			0x400

 #define MAX_PWMS			4

 struct pwm_lpss_chip {
 	struct pwm_chip chip;
 	void __iomem *regs;
 	const struct pwm_lpss_boardinfo *info;
 	u32 saved_ctrl[MAX_PWMS];
 };

 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
 {
 	return container_of(chip, struct pwm_lpss_chip, chip);
 }

 static inline u32 pwm_lpss_read(const struct pwm_device *pwm)
 {
 	struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);

 	return readl(lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
 }

 static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value)
 {
 	struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);

 	writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
 }

 static int pwm_lpss_wait_for_update(struct pwm_device *pwm)
 {
 	struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
 	const void __iomem *addr = lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM;
 	const unsigned int ms = 500 * USEC_PER_MSEC;
 	u32 val;
 	int err;

 	/*
 	 * PWM Configuration register has SW_UPDATE bit that is set when a new
 	 * configuration is written to the register. The bit is automatically
 	 * cleared at the start of the next output cycle by the IP block.
 	 *
 	 * If one writes a new configuration to the register while it still has
 	 * the bit enabled, PWM may freeze. That is, while one can still write
 	 * to the register, it won't have an effect. Thus, we try to sleep long
 	 * enough that the bit gets cleared and make sure the bit is not
 	 * enabled while we update the configuration.
 	 */
 	err = readl_poll_timeout(addr, val, !(val & PWM_SW_UPDATE), 40, ms);
 	if (err)
 		dev_err(pwm->chip->dev, "PWM_SW_UPDATE was not cleared\n");

 	return err;
 }

 static inline int pwm_lpss_is_updating(struct pwm_device *pwm)
 {
 	return (pwm_lpss_read(pwm) & PWM_SW_UPDATE) ? -EBUSY : 0;
 }

 static void pwm_lpss_prepare(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm,
 			     int duty_ns, int period_ns)
 {
 	unsigned long long on_time_div;
 	unsigned long c = lpwm->info->clk_rate, base_unit_range;
 	unsigned long long base_unit, freq = NSEC_PER_SEC;
 	u32 ctrl;

 	do_div(freq, period_ns);

 	/*
 	 * The equation is:
 	 * base_unit = round(base_unit_range * freq / c)
 	 */
 	base_unit_range = BIT(lpwm->info->base_unit_bits) - 1;
 	freq *= base_unit_range;

 	base_unit = DIV_ROUND_CLOSEST_ULL(freq, c);

 	on_time_div = 255ULL * duty_ns;
 	do_div(on_time_div, period_ns);
 	on_time_div = 255ULL - on_time_div;

 	ctrl = pwm_lpss_read(pwm);
 	ctrl &= ~PWM_ON_TIME_DIV_MASK;
 	ctrl &= ~(base_unit_range << PWM_BASE_UNIT_SHIFT);
 	base_unit &= base_unit_range;
 	ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT;
 	ctrl |= on_time_div;
 	pwm_lpss_write(pwm, ctrl);
 }

 static inline void pwm_lpss_cond_enable(struct pwm_device *pwm, bool cond)
 {
 	if (cond)
 		pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE);
 }

 static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			  struct pwm_state *state)
 {
 	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
 	int ret;

 	if (state->enabled) {
 		if (!pwm_is_enabled(pwm)) {
 			pm_runtime_get_sync(chip->dev);
 			ret = pwm_lpss_is_updating(pwm);
 			if (ret) {
 				pm_runtime_put(chip->dev);
 				return ret;
 			}
 			pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period);
 			pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_SW_UPDATE);
 			pwm_lpss_cond_enable(pwm, lpwm->info->bypass == false);
 			ret = pwm_lpss_wait_for_update(pwm);
 			if (ret) {
 				pm_runtime_put(chip->dev);
 				return ret;
 			}
 			pwm_lpss_cond_enable(pwm, lpwm->info->bypass == true);
 		} else {
 			ret = pwm_lpss_is_updating(pwm);
 			if (ret)
 				return ret;
 			pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period);
 			pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_SW_UPDATE);
 			return pwm_lpss_wait_for_update(pwm);
 		}
 	} else if (pwm_is_enabled(pwm)) {
 		pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
 		pm_runtime_put(chip->dev);
 	}

 	return 0;
 }

 static const struct pwm_ops pwm_lpss_ops = {
 	.apply = pwm_lpss_apply,
 	.owner = THIS_MODULE,
 };

 struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 				     const struct pwm_lpss_boardinfo *info)
 {
 	struct pwm_lpss_chip *lpwm;
 	unsigned long c;
 	int ret;

 	if (WARN_ON(info->npwm > MAX_PWMS))
 		return ERR_PTR(-ENODEV);

 	lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
 	if (!lpwm)
 		return ERR_PTR(-ENOMEM);

 	lpwm->regs = devm_ioremap_resource(dev, r);
 	if (IS_ERR(lpwm->regs))
 		return ERR_CAST(lpwm->regs);

 	lpwm->info = info;

 	c = lpwm->info->clk_rate;
 	if (!c)
 		return ERR_PTR(-EINVAL);

 	lpwm->chip.dev = dev;
 	lpwm->chip.ops = &pwm_lpss_ops;
 	lpwm->chip.base = -1;
 	lpwm->chip.npwm = info->npwm;

 	ret = pwmchip_add(&lpwm->chip);
 	if (ret) {
 		dev_err(dev, "failed to add PWM chip: %d\n", ret);
 		return ERR_PTR(ret);
 	}

 	return lpwm;
 }
 EXPORT_SYMBOL_GPL(pwm_lpss_probe);

 int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
 {
 	return pwmchip_remove(&lpwm->chip);
 }
 EXPORT_SYMBOL_GPL(pwm_lpss_remove);

 int pwm_lpss_suspend(struct device *dev)
 {
 	struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
 	int i;

 	for (i = 0; i < lpwm->info->npwm; i++)
 		lpwm->saved_ctrl[i] = readl(lpwm->regs + i * PWM_SIZE + PWM);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(pwm_lpss_suspend);

 int pwm_lpss_resume(struct device *dev)
 {
 	struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
 	int i;

 	for (i = 0; i < lpwm->info->npwm; i++)
 		writel(lpwm->saved_ctrl[i], lpwm->regs + i * PWM_SIZE + PWM);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(pwm_lpss_resume);

 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
 MODULE_LICENSE("GPL v2");
	/*
	* Intel Low Power Subsystem PWM controller driver
	*
	* Copyright (C) 2014, Intel Corporation
	* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
	* Author: Chew Kean Ho <kean.ho.chew@intel.com>
	* Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
	* Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
	* Author: Alan Cox <alan@linux.intel.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/delay.h>
	#include <linux/io.h>
	#include <linux/iopoll.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/pm_runtime.h>
	#include <linux/time.h>

	#include "pwm-lpss.h"

	#define PWM 0x00000000
	#define PWM_ENABLE BIT(31)
	#define PWM_SW_UPDATE BIT(30)
	#define PWM_BASE_UNIT_SHIFT 8
	#define PWM_ON_TIME_DIV_MASK 0x000000ff

	/* Size of each PWM register space if multiple */
	#define PWM_SIZE 0x400

	#define MAX_PWMS 4

	struct pwm_lpss_chip {
	struct pwm_chip chip;
	void __iomem *regs;
	const struct pwm_lpss_boardinfo *info;
	u32 saved_ctrl[MAX_PWMS];
	};

	static inline struct pwm_lpss_chip to_lpwm(struct pwm_chip chip)
	{
	return container_of(chip, struct pwm_lpss_chip, chip);
	}

	static inline u32 pwm_lpss_read(const struct pwm_device *pwm)
	{
	struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);

	return readl(lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
	}

	static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value)
	{
	struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);

	writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
	}

	static int pwm_lpss_wait_for_update(struct pwm_device *pwm)
	{
	struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
	const void __iomem addr = lpwm->regs + pwm->hwpwm PWM_SIZE + PWM;
	const unsigned int ms = 500 * USEC_PER_MSEC;
	u32 val;
	int err;

	/*
	* PWM Configuration register has SW_UPDATE bit that is set when a new
	* configuration is written to the register. The bit is automatically
	* cleared at the start of the next output cycle by the IP block.
	*
	* If one writes a new configuration to the register while it still has
	* the bit enabled, PWM may freeze. That is, while one can still write
	* to the register, it won't have an effect. Thus, we try to sleep long
	* enough that the bit gets cleared and make sure the bit is not
	* enabled while we update the configuration.
	*/
	err = readl_poll_timeout(addr, val, !(val & PWM_SW_UPDATE), 40, ms);
	if (err)
	dev_err(pwm->chip->dev, "PWM_SW_UPDATE was not cleared\n");

	return err;
	}

	static inline int pwm_lpss_is_updating(struct pwm_device *pwm)
	{
	return (pwm_lpss_read(pwm) & PWM_SW_UPDATE) ? -EBUSY : 0;
	}

	static void pwm_lpss_prepare(struct pwm_lpss_chip lpwm, struct pwm_device pwm,
	int duty_ns, int period_ns)
	{
	unsigned long long on_time_div;
	unsigned long c = lpwm->info->clk_rate, base_unit_range;
	unsigned long long base_unit, freq = NSEC_PER_SEC;
	u32 ctrl;

	do_div(freq, period_ns);

	/*
	* The equation is:
	* base_unit = round(base_unit_range * freq / c)
	*/
	base_unit_range = BIT(lpwm->info->base_unit_bits) - 1;
	freq *= base_unit_range;

	base_unit = DIV_ROUND_CLOSEST_ULL(freq, c);

	on_time_div = 255ULL * duty_ns;
	do_div(on_time_div, period_ns);
	on_time_div = 255ULL - on_time_div;

	ctrl = pwm_lpss_read(pwm);
	ctrl &= ~PWM_ON_TIME_DIV_MASK;
	ctrl &= ~(base_unit_range << PWM_BASE_UNIT_SHIFT);
	base_unit &= base_unit_range;
	ctrl \|= (u32) base_unit << PWM_BASE_UNIT_SHIFT;
	ctrl \|= on_time_div;
	pwm_lpss_write(pwm, ctrl);
	}

	static inline void pwm_lpss_cond_enable(struct pwm_device *pwm, bool cond)
	{
	if (cond)
	pwm_lpss_write(pwm, pwm_lpss_read(pwm) \| PWM_ENABLE);
	}

	static int pwm_lpss_apply(struct pwm_chip chip, struct pwm_device pwm,
	struct pwm_state *state)
	{
	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
	int ret;

	if (state->enabled) {
	if (!pwm_is_enabled(pwm)) {
	pm_runtime_get_sync(chip->dev);
	ret = pwm_lpss_is_updating(pwm);
	if (ret) {
	pm_runtime_put(chip->dev);
	return ret;
	}
	pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period);
	pwm_lpss_write(pwm, pwm_lpss_read(pwm) \| PWM_SW_UPDATE);
	pwm_lpss_cond_enable(pwm, lpwm->info->bypass == false);
	ret = pwm_lpss_wait_for_update(pwm);
	if (ret) {
	pm_runtime_put(chip->dev);
	return ret;
	}
	pwm_lpss_cond_enable(pwm, lpwm->info->bypass == true);
	} else {
	ret = pwm_lpss_is_updating(pwm);
	if (ret)
	return ret;
	pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period);
	pwm_lpss_write(pwm, pwm_lpss_read(pwm) \| PWM_SW_UPDATE);
	return pwm_lpss_wait_for_update(pwm);
	}
	} else if (pwm_is_enabled(pwm)) {
	pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
	pm_runtime_put(chip->dev);
	}

	return 0;
	}

	static const struct pwm_ops pwm_lpss_ops = {
	.apply = pwm_lpss_apply,
	.owner = THIS_MODULE,
	};

	struct pwm_lpss_chip pwm_lpss_probe(struct device dev, struct resource *r,
	const struct pwm_lpss_boardinfo *info)
	{
	struct pwm_lpss_chip *lpwm;
	unsigned long c;
	int ret;

	if (WARN_ON(info->npwm > MAX_PWMS))
	return ERR_PTR(-ENODEV);

	lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
	if (!lpwm)
	return ERR_PTR(-ENOMEM);

	lpwm->regs = devm_ioremap_resource(dev, r);
	if (IS_ERR(lpwm->regs))
	return ERR_CAST(lpwm->regs);

	lpwm->info = info;

	c = lpwm->info->clk_rate;
	if (!c)
	return ERR_PTR(-EINVAL);

	lpwm->chip.dev = dev;
	lpwm->chip.ops = &pwm_lpss_ops;
	lpwm->chip.base = -1;
	lpwm->chip.npwm = info->npwm;

	ret = pwmchip_add(&lpwm->chip);
	if (ret) {
	dev_err(dev, "failed to add PWM chip: %d\n", ret);
	return ERR_PTR(ret);
	}

	return lpwm;
	}
	EXPORT_SYMBOL_GPL(pwm_lpss_probe);

	int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
	{
	return pwmchip_remove(&lpwm->chip);
	}
	EXPORT_SYMBOL_GPL(pwm_lpss_remove);

	int pwm_lpss_suspend(struct device *dev)
	{
	struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
	int i;

	for (i = 0; i < lpwm->info->npwm; i++)
	lpwm->saved_ctrl[i] = readl(lpwm->regs + i * PWM_SIZE + PWM);

	return 0;
	}
	EXPORT_SYMBOL_GPL(pwm_lpss_suspend);

	int pwm_lpss_resume(struct device *dev)
	{
	struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
	int i;

	for (i = 0; i < lpwm->info->npwm; i++)
	writel(lpwm->saved_ctrl[i], lpwm->regs + i * PWM_SIZE + PWM);

	return 0;
	}
	EXPORT_SYMBOL_GPL(pwm_lpss_resume);

	MODULE_DESCRIPTION("PWM driver for Intel LPSS");
	MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
	MODULE_LICENSE("GPL v2");