drivers/pwm/pwm-tegra.c - third_party/linux - Git at Google

 /*
  * drivers/pwm/pwm-tegra.c
  *
  * Tegra pulse-width-modulation controller driver
  *
  * Copyright (c) 2010, NVIDIA Corporation.
  * Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  *
  * You should have received a copy of the GNU General Public License along
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */

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

 #define PWM_ENABLE	(1 << 31)
 #define PWM_DUTY_WIDTH	8
 #define PWM_DUTY_SHIFT	16
 #define PWM_SCALE_WIDTH	13
 #define PWM_SCALE_SHIFT	0

 #define NUM_PWM 4

 struct tegra_pwm_chip {
 	struct pwm_chip		chip;
 	struct device		*dev;

 	struct clk		*clk;

 	void __iomem		*mmio_base;
 };

 static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
 {
 	return container_of(chip, struct tegra_pwm_chip, chip);
 }

 static inline u32 pwm_readl(struct tegra_pwm_chip *chip, unsigned int num)
 {
 	return readl(chip->mmio_base + (num << 4));
 }

 static inline void pwm_writel(struct tegra_pwm_chip *chip, unsigned int num,
 			     unsigned long val)
 {
 	writel(val, chip->mmio_base + (num << 4));
 }

 static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			    int duty_ns, int period_ns)
 {
 	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 	unsigned long long c;
 	unsigned long rate, hz;
 	u32 val = 0;
 	int err;

 	/*
 	 * Convert from duty_ns / period_ns to a fixed number of duty ticks
 	 * per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
 	 * nearest integer during division.
 	 */
 	c = duty_ns * ((1 << PWM_DUTY_WIDTH) - 1) + period_ns / 2;
 	do_div(c, period_ns);

 	val = (u32)c << PWM_DUTY_SHIFT;

 	/*
 	 * Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
 	 * cycles at the PWM clock rate will take period_ns nanoseconds.
 	 */
 	rate = clk_get_rate(pc->clk) >> PWM_DUTY_WIDTH;
 	hz = 1000000000ul / period_ns;

 	rate = (rate + (hz / 2)) / hz;

 	/*
 	 * Since the actual PWM divider is the register's frequency divider
 	 * field minus 1, we need to decrement to get the correct value to
 	 * write to the register.
 	 */
 	if (rate > 0)
 		rate--;

 	/*
 	 * Make sure that the rate will fit in the register's frequency
 	 * divider field.
 	 */
 	if (rate >> PWM_SCALE_WIDTH)
 		return -EINVAL;

 	val |= rate << PWM_SCALE_SHIFT;

 	/*
 	 * If the PWM channel is disabled, make sure to turn on the clock
 	 * before writing the register. Otherwise, keep it enabled.
 	 */
 	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
 		err = clk_prepare_enable(pc->clk);
 		if (err < 0)
 			return err;
 	} else
 		val |= PWM_ENABLE;

 	pwm_writel(pc, pwm->hwpwm, val);

 	/*
 	 * If the PWM is not enabled, turn the clock off again to save power.
 	 */
 	if (!test_bit(PWMF_ENABLED, &pwm->flags))
 		clk_disable_unprepare(pc->clk);

 	return 0;
 }

 static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 	int rc = 0;
 	u32 val;

 	rc = clk_prepare_enable(pc->clk);
 	if (rc < 0)
 		return rc;

 	val = pwm_readl(pc, pwm->hwpwm);
 	val |= PWM_ENABLE;
 	pwm_writel(pc, pwm->hwpwm, val);

 	return 0;
 }

 static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 	u32 val;

 	val = pwm_readl(pc, pwm->hwpwm);
 	val &= ~PWM_ENABLE;
 	pwm_writel(pc, pwm->hwpwm, val);

 	clk_disable_unprepare(pc->clk);
 }

 static const struct pwm_ops tegra_pwm_ops = {
 	.config = tegra_pwm_config,
 	.enable = tegra_pwm_enable,
 	.disable = tegra_pwm_disable,
 	.owner = THIS_MODULE,
 };

 static int tegra_pwm_probe(struct platform_device *pdev)
 {
 	struct tegra_pwm_chip *pwm;
 	struct resource *r;
 	int ret;

 	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 	if (!pwm) {
 		dev_err(&pdev->dev, "failed to allocate memory\n");
 		return -ENOMEM;
 	}

 	pwm->dev = &pdev->dev;

 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!r) {
 		dev_err(&pdev->dev, "no memory resources defined\n");
 		return -ENODEV;
 	}

 	pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
 	if (IS_ERR(pwm->mmio_base))
 		return PTR_ERR(pwm->mmio_base);

 	platform_set_drvdata(pdev, pwm);

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

 	pwm->chip.dev = &pdev->dev;
 	pwm->chip.ops = &tegra_pwm_ops;
 	pwm->chip.base = -1;
 	pwm->chip.npwm = NUM_PWM;

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

 	return 0;
 }

 static int tegra_pwm_remove(struct platform_device *pdev)
 {
 	struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
 	int i;

 	if (WARN_ON(!pc))
 		return -ENODEV;

 	for (i = 0; i < NUM_PWM; i++) {
 		struct pwm_device *pwm = &pc->chip.pwms[i];

 		if (!test_bit(PWMF_ENABLED, &pwm->flags))
 			if (clk_prepare_enable(pc->clk) < 0)
 				continue;

 		pwm_writel(pc, i, 0);

 		clk_disable_unprepare(pc->clk);
 	}

 	return pwmchip_remove(&pc->chip);
 }

 #ifdef CONFIG_OF
 static struct of_device_id tegra_pwm_of_match[] = {
 	{ .compatible = "nvidia,tegra20-pwm" },
 	{ .compatible = "nvidia,tegra30-pwm" },
 	{ }
 };

 MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
 #endif

 static struct platform_driver tegra_pwm_driver = {
 	.driver = {
 		.name = "tegra-pwm",
 		.of_match_table = of_match_ptr(tegra_pwm_of_match),
 	},
 	.probe = tegra_pwm_probe,
 	.remove = tegra_pwm_remove,
 };

 module_platform_driver(tegra_pwm_driver);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("NVIDIA Corporation");
 MODULE_ALIAS("platform:tegra-pwm");
	/*
	* drivers/pwm/pwm-tegra.c
	*
	* Tegra pulse-width-modulation controller driver
	*
	* Copyright (c) 2010, NVIDIA Corporation.
	* Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*
	* You should have received a copy of the GNU General Public License along
	* with this program; if not, write to the Free Software Foundation, Inc.,
	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
	*/

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

	#define PWM_ENABLE (1 << 31)
	#define PWM_DUTY_WIDTH 8
	#define PWM_DUTY_SHIFT 16
	#define PWM_SCALE_WIDTH 13
	#define PWM_SCALE_SHIFT 0

	#define NUM_PWM 4

	struct tegra_pwm_chip {
	struct pwm_chip chip;
	struct device *dev;

	struct clk *clk;

	void __iomem *mmio_base;
	};

	static inline struct tegra_pwm_chip to_tegra_pwm_chip(struct pwm_chip chip)
	{
	return container_of(chip, struct tegra_pwm_chip, chip);
	}

	static inline u32 pwm_readl(struct tegra_pwm_chip *chip, unsigned int num)
	{
	return readl(chip->mmio_base + (num << 4));
	}

	static inline void pwm_writel(struct tegra_pwm_chip *chip, unsigned int num,
	unsigned long val)
	{
	writel(val, chip->mmio_base + (num << 4));
	}

	static int tegra_pwm_config(struct pwm_chip chip, struct pwm_device pwm,
	int duty_ns, int period_ns)
	{
	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
	unsigned long long c;
	unsigned long rate, hz;
	u32 val = 0;
	int err;

	/*
	* Convert from duty_ns / period_ns to a fixed number of duty ticks
	* per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
	* nearest integer during division.
	*/
	c = duty_ns * ((1 << PWM_DUTY_WIDTH) - 1) + period_ns / 2;
	do_div(c, period_ns);

	val = (u32)c << PWM_DUTY_SHIFT;

	/*
	* Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
	* cycles at the PWM clock rate will take period_ns nanoseconds.
	*/
	rate = clk_get_rate(pc->clk) >> PWM_DUTY_WIDTH;
	hz = 1000000000ul / period_ns;

	rate = (rate + (hz / 2)) / hz;

	/*
	* Since the actual PWM divider is the register's frequency divider
	* field minus 1, we need to decrement to get the correct value to
	* write to the register.
	*/
	if (rate > 0)
	rate--;

	/*
	* Make sure that the rate will fit in the register's frequency
	* divider field.
	*/
	if (rate >> PWM_SCALE_WIDTH)
	return -EINVAL;

	val \|= rate << PWM_SCALE_SHIFT;

	/*
	* If the PWM channel is disabled, make sure to turn on the clock
	* before writing the register. Otherwise, keep it enabled.
	*/
	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
	err = clk_prepare_enable(pc->clk);
	if (err < 0)
	return err;
	} else
	val \|= PWM_ENABLE;

	pwm_writel(pc, pwm->hwpwm, val);

	/*
	* If the PWM is not enabled, turn the clock off again to save power.
	*/
	if (!test_bit(PWMF_ENABLED, &pwm->flags))
	clk_disable_unprepare(pc->clk);

	return 0;
	}

	static int tegra_pwm_enable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
	int rc = 0;
	u32 val;

	rc = clk_prepare_enable(pc->clk);
	if (rc < 0)
	return rc;

	val = pwm_readl(pc, pwm->hwpwm);
	val \|= PWM_ENABLE;
	pwm_writel(pc, pwm->hwpwm, val);

	return 0;
	}

	static void tegra_pwm_disable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
	u32 val;

	val = pwm_readl(pc, pwm->hwpwm);
	val &= ~PWM_ENABLE;
	pwm_writel(pc, pwm->hwpwm, val);

	clk_disable_unprepare(pc->clk);
	}

	static const struct pwm_ops tegra_pwm_ops = {
	.config = tegra_pwm_config,
	.enable = tegra_pwm_enable,
	.disable = tegra_pwm_disable,
	.owner = THIS_MODULE,
	};

	static int tegra_pwm_probe(struct platform_device *pdev)
	{
	struct tegra_pwm_chip *pwm;
	struct resource *r;
	int ret;

	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
	if (!pwm) {
	dev_err(&pdev->dev, "failed to allocate memory\n");
	return -ENOMEM;
	}

	pwm->dev = &pdev->dev;

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!r) {
	dev_err(&pdev->dev, "no memory resources defined\n");
	return -ENODEV;
	}

	pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
	if (IS_ERR(pwm->mmio_base))
	return PTR_ERR(pwm->mmio_base);

	platform_set_drvdata(pdev, pwm);

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

	pwm->chip.dev = &pdev->dev;
	pwm->chip.ops = &tegra_pwm_ops;
	pwm->chip.base = -1;
	pwm->chip.npwm = NUM_PWM;

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

	return 0;
	}

	static int tegra_pwm_remove(struct platform_device *pdev)
	{
	struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
	int i;

	if (WARN_ON(!pc))
	return -ENODEV;

	for (i = 0; i < NUM_PWM; i++) {
	struct pwm_device *pwm = &pc->chip.pwms[i];

	if (!test_bit(PWMF_ENABLED, &pwm->flags))
	if (clk_prepare_enable(pc->clk) < 0)
	continue;

	pwm_writel(pc, i, 0);

	clk_disable_unprepare(pc->clk);
	}

	return pwmchip_remove(&pc->chip);
	}

	#ifdef CONFIG_OF
	static struct of_device_id tegra_pwm_of_match[] = {
	{ .compatible = "nvidia,tegra20-pwm" },
	{ .compatible = "nvidia,tegra30-pwm" },
	{ }
	};

	MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
	#endif

	static struct platform_driver tegra_pwm_driver = {
	.driver = {
	.name = "tegra-pwm",
	.of_match_table = of_match_ptr(tegra_pwm_of_match),
	},
	.probe = tegra_pwm_probe,
	.remove = tegra_pwm_remove,
	};

	module_platform_driver(tegra_pwm_driver);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("NVIDIA Corporation");
	MODULE_ALIAS("platform:tegra-pwm");