drivers/pwm/pwm-imx.c - arm/linux - Git at Google

 /*
  * simple driver for PWM (Pulse Width Modulator) controller
  *
  * 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.
  *
  * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
  */

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

 /* i.MX1 and i.MX21 share the same PWM function block: */

 #define MX1_PWMC			0x00   /* PWM Control Register */
 #define MX1_PWMS			0x04   /* PWM Sample Register */
 #define MX1_PWMP			0x08   /* PWM Period Register */

 #define MX1_PWMC_EN			(1 << 4)

 /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */

 #define MX3_PWMCR			0x00    /* PWM Control Register */
 #define MX3_PWMSR			0x04    /* PWM Status Register */
 #define MX3_PWMSAR			0x0C    /* PWM Sample Register */
 #define MX3_PWMPR			0x10    /* PWM Period Register */
 #define MX3_PWMCR_PRESCALER(x)		((((x) - 1) & 0xFFF) << 4)
 #define MX3_PWMCR_DOZEEN		(1 << 24)
 #define MX3_PWMCR_WAITEN		(1 << 23)
 #define MX3_PWMCR_DBGEN			(1 << 22)
 #define MX3_PWMCR_POUTC			(1 << 18)
 #define MX3_PWMCR_CLKSRC_IPG_HIGH	(2 << 16)
 #define MX3_PWMCR_CLKSRC_IPG		(1 << 16)
 #define MX3_PWMCR_SWR			(1 << 3)
 #define MX3_PWMCR_EN			(1 << 0)
 #define MX3_PWMSR_FIFOAV_4WORDS		0x4
 #define MX3_PWMSR_FIFOAV_MASK		0x7

 #define MX3_PWM_SWR_LOOP		5

 struct imx_chip {
 	struct clk	*clk_per;

 	void __iomem	*mmio_base;

 	struct pwm_chip	chip;
 };

 #define to_imx_chip(chip)	container_of(chip, struct imx_chip, chip)

 static int imx_pwm_config_v1(struct pwm_chip *chip,
 		struct pwm_device *pwm, int duty_ns, int period_ns)
 {
 	struct imx_chip *imx = to_imx_chip(chip);

 	/*
 	 * The PWM subsystem allows for exact frequencies. However,
 	 * I cannot connect a scope on my device to the PWM line and
 	 * thus cannot provide the program the PWM controller
 	 * exactly. Instead, I'm relying on the fact that the
 	 * Bootloader (u-boot or WinCE+haret) has programmed the PWM
 	 * function group already. So I'll just modify the PWM sample
 	 * register to follow the ratio of duty_ns vs. period_ns
 	 * accordingly.
 	 *
 	 * This is good enough for programming the brightness of
 	 * the LCD backlight.
 	 *
 	 * The real implementation would divide PERCLK[0] first by
 	 * both the prescaler (/1 .. /128) and then by CLKSEL
 	 * (/2 .. /16).
 	 */
 	u32 max = readl(imx->mmio_base + MX1_PWMP);
 	u32 p = max * duty_ns / period_ns;
 	writel(max - p, imx->mmio_base + MX1_PWMS);

 	return 0;
 }

 static int imx_pwm_enable_v1(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct imx_chip *imx = to_imx_chip(chip);
 	u32 val;
 	int ret;

 	ret = clk_prepare_enable(imx->clk_per);
 	if (ret < 0)
 		return ret;

 	val = readl(imx->mmio_base + MX1_PWMC);
 	val |= MX1_PWMC_EN;
 	writel(val, imx->mmio_base + MX1_PWMC);

 	return 0;
 }

 static void imx_pwm_disable_v1(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct imx_chip *imx = to_imx_chip(chip);
 	u32 val;

 	val = readl(imx->mmio_base + MX1_PWMC);
 	val &= ~MX1_PWMC_EN;
 	writel(val, imx->mmio_base + MX1_PWMC);

 	clk_disable_unprepare(imx->clk_per);
 }

 static void imx_pwm_sw_reset(struct pwm_chip *chip)
 {
 	struct imx_chip *imx = to_imx_chip(chip);
 	struct device *dev = chip->dev;
 	int wait_count = 0;
 	u32 cr;

 	writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
 	do {
 		usleep_range(200, 1000);
 		cr = readl(imx->mmio_base + MX3_PWMCR);
 	} while ((cr & MX3_PWMCR_SWR) &&
 		 (wait_count++ < MX3_PWM_SWR_LOOP));

 	if (cr & MX3_PWMCR_SWR)
 		dev_warn(dev, "software reset timeout\n");
 }

 static void imx_pwm_wait_fifo_slot(struct pwm_chip *chip,
 				   struct pwm_device *pwm)
 {
 	struct imx_chip *imx = to_imx_chip(chip);
 	struct device *dev = chip->dev;
 	unsigned int period_ms;
 	int fifoav;
 	u32 sr;

 	sr = readl(imx->mmio_base + MX3_PWMSR);
 	fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
 	if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
 		period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
 					 NSEC_PER_MSEC);
 		msleep(period_ms);

 		sr = readl(imx->mmio_base + MX3_PWMSR);
 		if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK))
 			dev_warn(dev, "there is no free FIFO slot\n");
 	}
 }

 static int imx_pwm_apply_v2(struct pwm_chip *chip, struct pwm_device *pwm,
 			    struct pwm_state *state)
 {
 	unsigned long period_cycles, duty_cycles, prescale;
 	struct imx_chip *imx = to_imx_chip(chip);
 	struct pwm_state cstate;
 	unsigned long long c;
 	int ret;
 	u32 cr;

 	pwm_get_state(pwm, &cstate);

 	if (state->enabled) {
 		c = clk_get_rate(imx->clk_per);
 		c *= state->period;

 		do_div(c, 1000000000);
 		period_cycles = c;

 		prescale = period_cycles / 0x10000 + 1;

 		period_cycles /= prescale;
 		c = (unsigned long long)period_cycles * state->duty_cycle;
 		do_div(c, state->period);
 		duty_cycles = c;

 		/*
 		 * according to imx pwm RM, the real period value should be
 		 * PERIOD value in PWMPR plus 2.
 		 */
 		if (period_cycles > 2)
 			period_cycles -= 2;
 		else
 			period_cycles = 0;

 		/*
 		 * Wait for a free FIFO slot if the PWM is already enabled, and
 		 * flush the FIFO if the PWM was disabled and is about to be
 		 * enabled.
 		 */
 		if (cstate.enabled) {
 			imx_pwm_wait_fifo_slot(chip, pwm);
 		} else {
 			ret = clk_prepare_enable(imx->clk_per);
 			if (ret)
 				return ret;

 			imx_pwm_sw_reset(chip);
 		}

 		writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
 		writel(period_cycles, imx->mmio_base + MX3_PWMPR);

 		cr = MX3_PWMCR_PRESCALER(prescale) |
 		     MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
 		     MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH |
 		     MX3_PWMCR_EN;

 		if (state->polarity == PWM_POLARITY_INVERSED)
 			cr |= MX3_PWMCR_POUTC;

 		writel(cr, imx->mmio_base + MX3_PWMCR);
 	} else if (cstate.enabled) {
 		writel(0, imx->mmio_base + MX3_PWMCR);

 		clk_disable_unprepare(imx->clk_per);
 	}

 	return 0;
 }

 static const struct pwm_ops imx_pwm_ops_v1 = {
 	.enable = imx_pwm_enable_v1,
 	.disable = imx_pwm_disable_v1,
 	.config = imx_pwm_config_v1,
 	.owner = THIS_MODULE,
 };

 static const struct pwm_ops imx_pwm_ops_v2 = {
 	.apply = imx_pwm_apply_v2,
 	.owner = THIS_MODULE,
 };

 struct imx_pwm_data {
 	bool polarity_supported;
 	const struct pwm_ops *ops;
 };

 static struct imx_pwm_data imx_pwm_data_v1 = {
 	.ops = &imx_pwm_ops_v1,
 };

 static struct imx_pwm_data imx_pwm_data_v2 = {
 	.polarity_supported = true,
 	.ops = &imx_pwm_ops_v2,
 };

 static const struct of_device_id imx_pwm_dt_ids[] = {
 	{ .compatible = "fsl,imx1-pwm", .data = &imx_pwm_data_v1, },
 	{ .compatible = "fsl,imx27-pwm", .data = &imx_pwm_data_v2, },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, imx_pwm_dt_ids);

 static int imx_pwm_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *of_id =
 			of_match_device(imx_pwm_dt_ids, &pdev->dev);
 	const struct imx_pwm_data *data;
 	struct imx_chip *imx;
 	struct resource *r;
 	int ret = 0;

 	if (!of_id)
 		return -ENODEV;

 	data = of_id->data;

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

 	imx->clk_per = devm_clk_get(&pdev->dev, "per");
 	if (IS_ERR(imx->clk_per)) {
 		dev_err(&pdev->dev, "getting per clock failed with %ld\n",
 				PTR_ERR(imx->clk_per));
 		return PTR_ERR(imx->clk_per);
 	}

 	imx->chip.ops = data->ops;
 	imx->chip.dev = &pdev->dev;
 	imx->chip.base = -1;
 	imx->chip.npwm = 1;

 	if (data->polarity_supported) {
 		dev_dbg(&pdev->dev, "PWM supports output inversion\n");
 		imx->chip.of_xlate = of_pwm_xlate_with_flags;
 		imx->chip.of_pwm_n_cells = 3;
 	}

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

 	ret = pwmchip_add(&imx->chip);
 	if (ret < 0)
 		return ret;

 	platform_set_drvdata(pdev, imx);
 	return 0;
 }

 static int imx_pwm_remove(struct platform_device *pdev)
 {
 	struct imx_chip *imx;

 	imx = platform_get_drvdata(pdev);
 	if (imx == NULL)
 		return -ENODEV;

 	return pwmchip_remove(&imx->chip);
 }

 static struct platform_driver imx_pwm_driver = {
 	.driver		= {
 		.name	= "imx-pwm",
 		.of_match_table = imx_pwm_dt_ids,
 	},
 	.probe		= imx_pwm_probe,
 	.remove		= imx_pwm_remove,
 };

 module_platform_driver(imx_pwm_driver);

 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
	/*
	* simple driver for PWM (Pulse Width Modulator) controller
	*
	* 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.
	*
	* Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
	*/

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

	/* i.MX1 and i.MX21 share the same PWM function block: */

	#define MX1_PWMC 0x00 /* PWM Control Register */
	#define MX1_PWMS 0x04 /* PWM Sample Register */
	#define MX1_PWMP 0x08 /* PWM Period Register */

	#define MX1_PWMC_EN (1 << 4)

	/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */

	#define MX3_PWMCR 0x00 /* PWM Control Register */
	#define MX3_PWMSR 0x04 /* PWM Status Register */
	#define MX3_PWMSAR 0x0C /* PWM Sample Register */
	#define MX3_PWMPR 0x10 /* PWM Period Register */
	#define MX3_PWMCR_PRESCALER(x) ((((x) - 1) & 0xFFF) << 4)
	#define MX3_PWMCR_DOZEEN (1 << 24)
	#define MX3_PWMCR_WAITEN (1 << 23)
	#define MX3_PWMCR_DBGEN (1 << 22)
	#define MX3_PWMCR_POUTC (1 << 18)
	#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
	#define MX3_PWMCR_CLKSRC_IPG (1 << 16)
	#define MX3_PWMCR_SWR (1 << 3)
	#define MX3_PWMCR_EN (1 << 0)
	#define MX3_PWMSR_FIFOAV_4WORDS 0x4
	#define MX3_PWMSR_FIFOAV_MASK 0x7

	#define MX3_PWM_SWR_LOOP 5

	struct imx_chip {
	struct clk *clk_per;

	void __iomem *mmio_base;

	struct pwm_chip chip;
	};

	#define to_imx_chip(chip) container_of(chip, struct imx_chip, chip)

	static int imx_pwm_config_v1(struct pwm_chip *chip,
	struct pwm_device *pwm, int duty_ns, int period_ns)
	{
	struct imx_chip *imx = to_imx_chip(chip);

	/*
	* The PWM subsystem allows for exact frequencies. However,
	* I cannot connect a scope on my device to the PWM line and
	* thus cannot provide the program the PWM controller
	* exactly. Instead, I'm relying on the fact that the
	* Bootloader (u-boot or WinCE+haret) has programmed the PWM
	* function group already. So I'll just modify the PWM sample
	* register to follow the ratio of duty_ns vs. period_ns
	* accordingly.
	*
	* This is good enough for programming the brightness of
	* the LCD backlight.
	*
	* The real implementation would divide PERCLK[0] first by
	* both the prescaler (/1 .. /128) and then by CLKSEL
	* (/2 .. /16).
	*/
	u32 max = readl(imx->mmio_base + MX1_PWMP);
	u32 p = max * duty_ns / period_ns;
	writel(max - p, imx->mmio_base + MX1_PWMS);

	return 0;
	}

	static int imx_pwm_enable_v1(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct imx_chip *imx = to_imx_chip(chip);
	u32 val;
	int ret;

	ret = clk_prepare_enable(imx->clk_per);
	if (ret < 0)
	return ret;

	val = readl(imx->mmio_base + MX1_PWMC);
	val \|= MX1_PWMC_EN;
	writel(val, imx->mmio_base + MX1_PWMC);

	return 0;
	}

	static void imx_pwm_disable_v1(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct imx_chip *imx = to_imx_chip(chip);
	u32 val;

	val = readl(imx->mmio_base + MX1_PWMC);
	val &= ~MX1_PWMC_EN;
	writel(val, imx->mmio_base + MX1_PWMC);

	clk_disable_unprepare(imx->clk_per);
	}

	static void imx_pwm_sw_reset(struct pwm_chip *chip)
	{
	struct imx_chip *imx = to_imx_chip(chip);
	struct device *dev = chip->dev;
	int wait_count = 0;
	u32 cr;

	writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
	do {
	usleep_range(200, 1000);
	cr = readl(imx->mmio_base + MX3_PWMCR);
	} while ((cr & MX3_PWMCR_SWR) &&
	(wait_count++ < MX3_PWM_SWR_LOOP));

	if (cr & MX3_PWMCR_SWR)
	dev_warn(dev, "software reset timeout\n");
	}

	static void imx_pwm_wait_fifo_slot(struct pwm_chip *chip,
	struct pwm_device *pwm)
	{
	struct imx_chip *imx = to_imx_chip(chip);
	struct device *dev = chip->dev;
	unsigned int period_ms;
	int fifoav;
	u32 sr;

	sr = readl(imx->mmio_base + MX3_PWMSR);
	fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
	if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
	period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
	NSEC_PER_MSEC);
	msleep(period_ms);

	sr = readl(imx->mmio_base + MX3_PWMSR);
	if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK))
	dev_warn(dev, "there is no free FIFO slot\n");
	}
	}

	static int imx_pwm_apply_v2(struct pwm_chip chip, struct pwm_device pwm,
	struct pwm_state *state)
	{
	unsigned long period_cycles, duty_cycles, prescale;
	struct imx_chip *imx = to_imx_chip(chip);
	struct pwm_state cstate;
	unsigned long long c;
	int ret;
	u32 cr;

	pwm_get_state(pwm, &cstate);

	if (state->enabled) {
	c = clk_get_rate(imx->clk_per);
	c *= state->period;

	do_div(c, 1000000000);
	period_cycles = c;

	prescale = period_cycles / 0x10000 + 1;

	period_cycles /= prescale;
	c = (unsigned long long)period_cycles * state->duty_cycle;
	do_div(c, state->period);
	duty_cycles = c;

	/*
	* according to imx pwm RM, the real period value should be
	* PERIOD value in PWMPR plus 2.
	*/
	if (period_cycles > 2)
	period_cycles -= 2;
	else
	period_cycles = 0;

	/*
	* Wait for a free FIFO slot if the PWM is already enabled, and
	* flush the FIFO if the PWM was disabled and is about to be
	* enabled.
	*/
	if (cstate.enabled) {
	imx_pwm_wait_fifo_slot(chip, pwm);
	} else {
	ret = clk_prepare_enable(imx->clk_per);
	if (ret)
	return ret;

	imx_pwm_sw_reset(chip);
	}

	writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
	writel(period_cycles, imx->mmio_base + MX3_PWMPR);

	cr = MX3_PWMCR_PRESCALER(prescale) \|
	MX3_PWMCR_DOZEEN \| MX3_PWMCR_WAITEN \|
	MX3_PWMCR_DBGEN \| MX3_PWMCR_CLKSRC_IPG_HIGH \|
	MX3_PWMCR_EN;

	if (state->polarity == PWM_POLARITY_INVERSED)
	cr \|= MX3_PWMCR_POUTC;

	writel(cr, imx->mmio_base + MX3_PWMCR);
	} else if (cstate.enabled) {
	writel(0, imx->mmio_base + MX3_PWMCR);

	clk_disable_unprepare(imx->clk_per);
	}

	return 0;
	}

	static const struct pwm_ops imx_pwm_ops_v1 = {
	.enable = imx_pwm_enable_v1,
	.disable = imx_pwm_disable_v1,
	.config = imx_pwm_config_v1,
	.owner = THIS_MODULE,
	};

	static const struct pwm_ops imx_pwm_ops_v2 = {
	.apply = imx_pwm_apply_v2,
	.owner = THIS_MODULE,
	};

	struct imx_pwm_data {
	bool polarity_supported;
	const struct pwm_ops *ops;
	};

	static struct imx_pwm_data imx_pwm_data_v1 = {
	.ops = &imx_pwm_ops_v1,
	};

	static struct imx_pwm_data imx_pwm_data_v2 = {
	.polarity_supported = true,
	.ops = &imx_pwm_ops_v2,
	};

	static const struct of_device_id imx_pwm_dt_ids[] = {
	{ .compatible = "fsl,imx1-pwm", .data = &imx_pwm_data_v1, },
	{ .compatible = "fsl,imx27-pwm", .data = &imx_pwm_data_v2, },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, imx_pwm_dt_ids);

	static int imx_pwm_probe(struct platform_device *pdev)
	{
	const struct of_device_id *of_id =
	of_match_device(imx_pwm_dt_ids, &pdev->dev);
	const struct imx_pwm_data *data;
	struct imx_chip *imx;
	struct resource *r;
	int ret = 0;

	if (!of_id)
	return -ENODEV;

	data = of_id->data;

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

	imx->clk_per = devm_clk_get(&pdev->dev, "per");
	if (IS_ERR(imx->clk_per)) {
	dev_err(&pdev->dev, "getting per clock failed with %ld\n",
	PTR_ERR(imx->clk_per));
	return PTR_ERR(imx->clk_per);
	}

	imx->chip.ops = data->ops;
	imx->chip.dev = &pdev->dev;
	imx->chip.base = -1;
	imx->chip.npwm = 1;

	if (data->polarity_supported) {
	dev_dbg(&pdev->dev, "PWM supports output inversion\n");
	imx->chip.of_xlate = of_pwm_xlate_with_flags;
	imx->chip.of_pwm_n_cells = 3;
	}

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

	ret = pwmchip_add(&imx->chip);
	if (ret < 0)
	return ret;

	platform_set_drvdata(pdev, imx);
	return 0;
	}

	static int imx_pwm_remove(struct platform_device *pdev)
	{
	struct imx_chip *imx;

	imx = platform_get_drvdata(pdev);
	if (imx == NULL)
	return -ENODEV;

	return pwmchip_remove(&imx->chip);
	}

	static struct platform_driver imx_pwm_driver = {
	.driver = {
	.name = "imx-pwm",
	.of_match_table = imx_pwm_dt_ids,
	},
	.probe = imx_pwm_probe,
	.remove = imx_pwm_remove,
	};

	module_platform_driver(imx_pwm_driver);

	MODULE_LICENSE("GPL v2");
	MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");