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

 /*
  * ST Microelectronics SPEAr Pulse Width Modulator driver
  *
  * Copyright (C) 2012 ST Microelectronics
  * Shiraz Hashim <shiraz.linux.kernel@gmail.com>
  *
  * This file is licensed under the terms of the GNU General Public
  * License version 2. This program is licensed "as is" without any
  * warranty of any kind, whether express or implied.
  */

 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
 #include <linux/math64.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/slab.h>
 #include <linux/types.h>

 #define NUM_PWM		4

 /* PWM registers and bits definitions */
 #define PWMCR			0x00	/* Control Register */
 #define PWMCR_PWM_ENABLE	0x1
 #define PWMCR_PRESCALE_SHIFT	2
 #define PWMCR_MIN_PRESCALE	0x00
 #define PWMCR_MAX_PRESCALE	0x3FFF

 #define PWMDCR			0x04	/* Duty Cycle Register */
 #define PWMDCR_MIN_DUTY		0x0001
 #define PWMDCR_MAX_DUTY		0xFFFF

 #define PWMPCR			0x08	/* Period Register */
 #define PWMPCR_MIN_PERIOD	0x0001
 #define PWMPCR_MAX_PERIOD	0xFFFF

 /* Following only available on 13xx SoCs */
 #define PWMMCR			0x3C	/* Master Control Register */
 #define PWMMCR_PWM_ENABLE	0x1

 /**
  * struct spear_pwm_chip - struct representing pwm chip
  *
  * @mmio_base: base address of pwm chip
  * @clk: pointer to clk structure of pwm chip
  * @chip: linux pwm chip representation
  */
 struct spear_pwm_chip {
 	void __iomem *mmio_base;
 	struct clk *clk;
 	struct pwm_chip chip;
 };

 static inline struct spear_pwm_chip *to_spear_pwm_chip(struct pwm_chip *chip)
 {
 	return container_of(chip, struct spear_pwm_chip, chip);
 }

 static inline u32 spear_pwm_readl(struct spear_pwm_chip *chip, unsigned int num,
 				  unsigned long offset)
 {
 	return readl_relaxed(chip->mmio_base + (num << 4) + offset);
 }

 static inline void spear_pwm_writel(struct spear_pwm_chip *chip,
 				    unsigned int num, unsigned long offset,
 				    unsigned long val)
 {
 	writel_relaxed(val, chip->mmio_base + (num << 4) + offset);
 }

 static int spear_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			    int duty_ns, int period_ns)
 {
 	struct spear_pwm_chip *pc = to_spear_pwm_chip(chip);
 	u64 val, div, clk_rate;
 	unsigned long prescale = PWMCR_MIN_PRESCALE, pv, dc;
 	int ret;

 	/*
 	 * Find pv, dc and prescale to suit duty_ns and period_ns. This is done
 	 * according to formulas described below:
 	 *
 	 * period_ns = 10^9 * (PRESCALE + 1) * PV / PWM_CLK_RATE
 	 * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 	 *
 	 * PV = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
 	 * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
 	 */
 	clk_rate = clk_get_rate(pc->clk);
 	while (1) {
 		div = 1000000000;
 		div *= 1 + prescale;
 		val = clk_rate * period_ns;
 		pv = div64_u64(val, div);
 		val = clk_rate * duty_ns;
 		dc = div64_u64(val, div);

 		/* if duty_ns and period_ns are not achievable then return */
 		if (pv < PWMPCR_MIN_PERIOD || dc < PWMDCR_MIN_DUTY)
 			return -EINVAL;

 		/*
 		 * if pv and dc have crossed their upper limit, then increase
 		 * prescale and recalculate pv and dc.
 		 */
 		if (pv > PWMPCR_MAX_PERIOD || dc > PWMDCR_MAX_DUTY) {
 			if (++prescale > PWMCR_MAX_PRESCALE)
 				return -EINVAL;
 			continue;
 		}
 		break;
 	}

 	/*
 	 * NOTE: the clock to PWM has to be enabled first before writing to the
 	 * registers.
 	 */
 	ret = clk_enable(pc->clk);
 	if (ret)
 		return ret;

 	spear_pwm_writel(pc, pwm->hwpwm, PWMCR,
 			prescale << PWMCR_PRESCALE_SHIFT);
 	spear_pwm_writel(pc, pwm->hwpwm, PWMDCR, dc);
 	spear_pwm_writel(pc, pwm->hwpwm, PWMPCR, pv);
 	clk_disable(pc->clk);

 	return 0;
 }

 static int spear_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct spear_pwm_chip *pc = to_spear_pwm_chip(chip);
 	int rc = 0;
 	u32 val;

 	rc = clk_enable(pc->clk);
 	if (rc)
 		return rc;

 	val = spear_pwm_readl(pc, pwm->hwpwm, PWMCR);
 	val |= PWMCR_PWM_ENABLE;
 	spear_pwm_writel(pc, pwm->hwpwm, PWMCR, val);

 	return 0;
 }

 static void spear_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct spear_pwm_chip *pc = to_spear_pwm_chip(chip);
 	u32 val;

 	val = spear_pwm_readl(pc, pwm->hwpwm, PWMCR);
 	val &= ~PWMCR_PWM_ENABLE;
 	spear_pwm_writel(pc, pwm->hwpwm, PWMCR, val);

 	clk_disable(pc->clk);
 }

 static const struct pwm_ops spear_pwm_ops = {
 	.config = spear_pwm_config,
 	.enable = spear_pwm_enable,
 	.disable = spear_pwm_disable,
 	.owner = THIS_MODULE,
 };

 static int spear_pwm_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct spear_pwm_chip *pc;
 	struct resource *r;
 	int ret;
 	u32 val;

 	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
 	if (!pc)
 		return -ENOMEM;

 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	pc->mmio_base = devm_ioremap_resource(&pdev->dev, r);
 	if (IS_ERR(pc->mmio_base))
 		return PTR_ERR(pc->mmio_base);

 	pc->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(pc->clk))
 		return PTR_ERR(pc->clk);

 	platform_set_drvdata(pdev, pc);

 	pc->chip.dev = &pdev->dev;
 	pc->chip.ops = &spear_pwm_ops;
 	pc->chip.base = -1;
 	pc->chip.npwm = NUM_PWM;

 	ret = clk_prepare(pc->clk);
 	if (ret)
 		return ret;

 	if (of_device_is_compatible(np, "st,spear1340-pwm")) {
 		ret = clk_enable(pc->clk);
 		if (ret) {
 			clk_unprepare(pc->clk);
 			return ret;
 		}
 		/*
 		 * Following enables PWM chip, channels would still be
 		 * enabled individually through their control register
 		 */
 		val = readl_relaxed(pc->mmio_base + PWMMCR);
 		val |= PWMMCR_PWM_ENABLE;
 		writel_relaxed(val, pc->mmio_base + PWMMCR);

 		clk_disable(pc->clk);
 	}

 	ret = pwmchip_add(&pc->chip);
 	if (ret < 0) {
 		clk_unprepare(pc->clk);
 		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 	}

 	return ret;
 }

 static int spear_pwm_remove(struct platform_device *pdev)
 {
 	struct spear_pwm_chip *pc = platform_get_drvdata(pdev);
 	int i;

 	for (i = 0; i < NUM_PWM; i++)
 		pwm_disable(&pc->chip.pwms[i]);

 	/* clk was prepared in probe, hence unprepare it here */
 	clk_unprepare(pc->clk);
 	return pwmchip_remove(&pc->chip);
 }

 static const struct of_device_id spear_pwm_of_match[] = {
 	{ .compatible = "st,spear320-pwm" },
 	{ .compatible = "st,spear1340-pwm" },
 	{ }
 };

 MODULE_DEVICE_TABLE(of, spear_pwm_of_match);

 static struct platform_driver spear_pwm_driver = {
 	.driver = {
 		.name = "spear-pwm",
 		.of_match_table = spear_pwm_of_match,
 	},
 	.probe = spear_pwm_probe,
 	.remove = spear_pwm_remove,
 };

 module_platform_driver(spear_pwm_driver);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Shiraz Hashim <shiraz.linux.kernel@gmail.com>");
 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.com>");
 MODULE_ALIAS("platform:spear-pwm");
	/*
	* ST Microelectronics SPEAr Pulse Width Modulator driver
	*
	* Copyright (C) 2012 ST Microelectronics
	* Shiraz Hashim <shiraz.linux.kernel@gmail.com>
	*
	* This file is licensed under the terms of the GNU General Public
	* License version 2. This program is licensed "as is" without any
	* warranty of any kind, whether express or implied.
	*/

	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include <linux/ioport.h>
	#include <linux/kernel.h>
	#include <linux/math64.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/pwm.h>
	#include <linux/slab.h>
	#include <linux/types.h>

	#define NUM_PWM 4

	/* PWM registers and bits definitions */
	#define PWMCR 0x00 /* Control Register */
	#define PWMCR_PWM_ENABLE 0x1
	#define PWMCR_PRESCALE_SHIFT 2
	#define PWMCR_MIN_PRESCALE 0x00
	#define PWMCR_MAX_PRESCALE 0x3FFF

	#define PWMDCR 0x04 /* Duty Cycle Register */
	#define PWMDCR_MIN_DUTY 0x0001
	#define PWMDCR_MAX_DUTY 0xFFFF

	#define PWMPCR 0x08 /* Period Register */
	#define PWMPCR_MIN_PERIOD 0x0001
	#define PWMPCR_MAX_PERIOD 0xFFFF

	/* Following only available on 13xx SoCs */
	#define PWMMCR 0x3C /* Master Control Register */
	#define PWMMCR_PWM_ENABLE 0x1

	/**
	* struct spear_pwm_chip - struct representing pwm chip
	*
	* @mmio_base: base address of pwm chip
	* @clk: pointer to clk structure of pwm chip
	* @chip: linux pwm chip representation
	*/
	struct spear_pwm_chip {
	void __iomem *mmio_base;
	struct clk *clk;
	struct pwm_chip chip;
	};

	static inline struct spear_pwm_chip to_spear_pwm_chip(struct pwm_chip chip)
	{
	return container_of(chip, struct spear_pwm_chip, chip);
	}

	static inline u32 spear_pwm_readl(struct spear_pwm_chip *chip, unsigned int num,
	unsigned long offset)
	{
	return readl_relaxed(chip->mmio_base + (num << 4) + offset);
	}

	static inline void spear_pwm_writel(struct spear_pwm_chip *chip,
	unsigned int num, unsigned long offset,
	unsigned long val)
	{
	writel_relaxed(val, chip->mmio_base + (num << 4) + offset);
	}

	static int spear_pwm_config(struct pwm_chip chip, struct pwm_device pwm,
	int duty_ns, int period_ns)
	{
	struct spear_pwm_chip *pc = to_spear_pwm_chip(chip);
	u64 val, div, clk_rate;
	unsigned long prescale = PWMCR_MIN_PRESCALE, pv, dc;
	int ret;

	/*
	* Find pv, dc and prescale to suit duty_ns and period_ns. This is done
	* according to formulas described below:
	*
	* period_ns = 10^9 * (PRESCALE + 1) * PV / PWM_CLK_RATE
	* duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
	*
	* PV = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
	* DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
	*/
	clk_rate = clk_get_rate(pc->clk);
	while (1) {
	div = 1000000000;
	div *= 1 + prescale;
	val = clk_rate * period_ns;
	pv = div64_u64(val, div);
	val = clk_rate * duty_ns;
	dc = div64_u64(val, div);

	/* if duty_ns and period_ns are not achievable then return */
	if (pv < PWMPCR_MIN_PERIOD \|\| dc < PWMDCR_MIN_DUTY)
	return -EINVAL;

	/*
	* if pv and dc have crossed their upper limit, then increase
	* prescale and recalculate pv and dc.
	*/
	if (pv > PWMPCR_MAX_PERIOD \|\| dc > PWMDCR_MAX_DUTY) {
	if (++prescale > PWMCR_MAX_PRESCALE)
	return -EINVAL;
	continue;
	}
	break;
	}

	/*
	* NOTE: the clock to PWM has to be enabled first before writing to the
	* registers.
	*/
	ret = clk_enable(pc->clk);
	if (ret)
	return ret;

	spear_pwm_writel(pc, pwm->hwpwm, PWMCR,
	prescale << PWMCR_PRESCALE_SHIFT);
	spear_pwm_writel(pc, pwm->hwpwm, PWMDCR, dc);
	spear_pwm_writel(pc, pwm->hwpwm, PWMPCR, pv);
	clk_disable(pc->clk);

	return 0;
	}

	static int spear_pwm_enable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct spear_pwm_chip *pc = to_spear_pwm_chip(chip);
	int rc = 0;
	u32 val;

	rc = clk_enable(pc->clk);
	if (rc)
	return rc;

	val = spear_pwm_readl(pc, pwm->hwpwm, PWMCR);
	val \|= PWMCR_PWM_ENABLE;
	spear_pwm_writel(pc, pwm->hwpwm, PWMCR, val);

	return 0;
	}

	static void spear_pwm_disable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct spear_pwm_chip *pc = to_spear_pwm_chip(chip);
	u32 val;

	val = spear_pwm_readl(pc, pwm->hwpwm, PWMCR);
	val &= ~PWMCR_PWM_ENABLE;
	spear_pwm_writel(pc, pwm->hwpwm, PWMCR, val);

	clk_disable(pc->clk);
	}

	static const struct pwm_ops spear_pwm_ops = {
	.config = spear_pwm_config,
	.enable = spear_pwm_enable,
	.disable = spear_pwm_disable,
	.owner = THIS_MODULE,
	};

	static int spear_pwm_probe(struct platform_device *pdev)
	{
	struct device_node *np = pdev->dev.of_node;
	struct spear_pwm_chip *pc;
	struct resource *r;
	int ret;
	u32 val;

	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
	if (!pc)
	return -ENOMEM;

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	pc->mmio_base = devm_ioremap_resource(&pdev->dev, r);
	if (IS_ERR(pc->mmio_base))
	return PTR_ERR(pc->mmio_base);

	pc->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(pc->clk))
	return PTR_ERR(pc->clk);

	platform_set_drvdata(pdev, pc);

	pc->chip.dev = &pdev->dev;
	pc->chip.ops = &spear_pwm_ops;
	pc->chip.base = -1;
	pc->chip.npwm = NUM_PWM;

	ret = clk_prepare(pc->clk);
	if (ret)
	return ret;

	if (of_device_is_compatible(np, "st,spear1340-pwm")) {
	ret = clk_enable(pc->clk);
	if (ret) {
	clk_unprepare(pc->clk);
	return ret;
	}
	/*
	* Following enables PWM chip, channels would still be
	* enabled individually through their control register
	*/
	val = readl_relaxed(pc->mmio_base + PWMMCR);
	val \|= PWMMCR_PWM_ENABLE;
	writel_relaxed(val, pc->mmio_base + PWMMCR);

	clk_disable(pc->clk);
	}

	ret = pwmchip_add(&pc->chip);
	if (ret < 0) {
	clk_unprepare(pc->clk);
	dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
	}

	return ret;
	}

	static int spear_pwm_remove(struct platform_device *pdev)
	{
	struct spear_pwm_chip *pc = platform_get_drvdata(pdev);
	int i;

	for (i = 0; i < NUM_PWM; i++)
	pwm_disable(&pc->chip.pwms[i]);

	/* clk was prepared in probe, hence unprepare it here */
	clk_unprepare(pc->clk);
	return pwmchip_remove(&pc->chip);
	}

	static const struct of_device_id spear_pwm_of_match[] = {
	{ .compatible = "st,spear320-pwm" },
	{ .compatible = "st,spear1340-pwm" },
	{ }
	};

	MODULE_DEVICE_TABLE(of, spear_pwm_of_match);

	static struct platform_driver spear_pwm_driver = {
	.driver = {
	.name = "spear-pwm",
	.of_match_table = spear_pwm_of_match,
	},
	.probe = spear_pwm_probe,
	.remove = spear_pwm_remove,
	};

	module_platform_driver(spear_pwm_driver);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Shiraz Hashim <shiraz.linux.kernel@gmail.com>");
	MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.com>");
	MODULE_ALIAS("platform:spear-pwm");