drivers/pwm/pwm-jz4740.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
  *  JZ4740 platform PWM support
  *
  * Limitations:
  * - The .apply callback doesn't complete the currently running period before
  *   reconfiguring the hardware.
  */

 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/gpio.h>
 #include <linux/kernel.h>
 #include <linux/mfd/ingenic-tcu.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/regmap.h>

 struct soc_info {
 	unsigned int num_pwms;
 };

 struct jz4740_pwm_chip {
 	struct pwm_chip chip;
 	struct regmap *map;
 };

 static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
 {
 	return container_of(chip, struct jz4740_pwm_chip, chip);
 }

 static bool jz4740_pwm_can_use_chn(struct jz4740_pwm_chip *jz,
 				   unsigned int channel)
 {
 	/* Enable all TCU channels for PWM use by default except channels 0/1 */
 	u32 pwm_channels_mask = GENMASK(jz->chip.npwm - 1, 2);

 	device_property_read_u32(jz->chip.dev->parent,
 				 "ingenic,pwm-channels-mask",
 				 &pwm_channels_mask);

 	return !!(pwm_channels_mask & BIT(channel));
 }

 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct jz4740_pwm_chip *jz = to_jz4740(chip);
 	struct clk *clk;
 	char name[16];
 	int err;

 	if (!jz4740_pwm_can_use_chn(jz, pwm->hwpwm))
 		return -EBUSY;

 	snprintf(name, sizeof(name), "timer%u", pwm->hwpwm);

 	clk = clk_get(chip->dev, name);
 	if (IS_ERR(clk))
 		return dev_err_probe(chip->dev, PTR_ERR(clk),
 				     "Failed to get clock\n");

 	err = clk_prepare_enable(clk);
 	if (err < 0) {
 		clk_put(clk);
 		return err;
 	}

 	pwm_set_chip_data(pwm, clk);

 	return 0;
 }

 static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct clk *clk = pwm_get_chip_data(pwm);

 	clk_disable_unprepare(clk);
 	clk_put(clk);
 }

 static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct jz4740_pwm_chip *jz = to_jz4740(chip);

 	/* Enable PWM output */
 	regmap_update_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
 			   TCU_TCSR_PWM_EN, TCU_TCSR_PWM_EN);

 	/* Start counter */
 	regmap_write(jz->map, TCU_REG_TESR, BIT(pwm->hwpwm));

 	return 0;
 }

 static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct jz4740_pwm_chip *jz = to_jz4740(chip);

 	/*
 	 * Set duty > period. This trick allows the TCU channels in TCU2 mode to
 	 * properly return to their init level.
 	 */
 	regmap_write(jz->map, TCU_REG_TDHRc(pwm->hwpwm), 0xffff);
 	regmap_write(jz->map, TCU_REG_TDFRc(pwm->hwpwm), 0x0);

 	/*
 	 * Disable PWM output.
 	 * In TCU2 mode (channel 1/2 on JZ4750+), this must be done before the
 	 * counter is stopped, while in TCU1 mode the order does not matter.
 	 */
 	regmap_update_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
 			   TCU_TCSR_PWM_EN, 0);

 	/* Stop counter */
 	regmap_write(jz->map, TCU_REG_TECR, BIT(pwm->hwpwm));
 }

 static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			    const struct pwm_state *state)
 {
 	struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
 	unsigned long long tmp = 0xffffull * NSEC_PER_SEC;
 	struct clk *clk = pwm_get_chip_data(pwm);
 	unsigned long period, duty;
 	long rate;
 	int err;

 	/*
 	 * Limit the clock to a maximum rate that still gives us a period value
 	 * which fits in 16 bits.
 	 */
 	do_div(tmp, state->period);

 	/*
 	 * /!\ IMPORTANT NOTE:
 	 * -------------------
 	 * This code relies on the fact that clk_round_rate() will always round
 	 * down, which is not a valid assumption given by the clk API, but only
 	 * happens to be true with the clk drivers used for Ingenic SoCs.
 	 *
 	 * Right now, there is no alternative as the clk API does not have a
 	 * round-down function (and won't have one for a while), but if it ever
 	 * comes to light, a round-down function should be used instead.
 	 */
 	rate = clk_round_rate(clk, tmp);
 	if (rate < 0) {
 		dev_err(chip->dev, "Unable to round rate: %ld", rate);
 		return rate;
 	}

 	/* Calculate period value */
 	tmp = (unsigned long long)rate * state->period;
 	do_div(tmp, NSEC_PER_SEC);
 	period = tmp;

 	/* Calculate duty value */
 	tmp = (unsigned long long)rate * state->duty_cycle;
 	do_div(tmp, NSEC_PER_SEC);
 	duty = tmp;

 	if (duty >= period)
 		duty = period - 1;

 	jz4740_pwm_disable(chip, pwm);

 	err = clk_set_rate(clk, rate);
 	if (err) {
 		dev_err(chip->dev, "Unable to set rate: %d", err);
 		return err;
 	}

 	/* Reset counter to 0 */
 	regmap_write(jz4740->map, TCU_REG_TCNTc(pwm->hwpwm), 0);

 	/* Set duty */
 	regmap_write(jz4740->map, TCU_REG_TDHRc(pwm->hwpwm), duty);

 	/* Set period */
 	regmap_write(jz4740->map, TCU_REG_TDFRc(pwm->hwpwm), period);

 	/* Set abrupt shutdown */
 	regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
 			   TCU_TCSR_PWM_SD, TCU_TCSR_PWM_SD);

 	/*
 	 * Set polarity.
 	 *
 	 * The PWM starts in inactive state until the internal timer reaches the
 	 * duty value, then becomes active until the timer reaches the period
 	 * value. In theory, we should then use (period - duty) as the real duty
 	 * value, as a high duty value would otherwise result in the PWM pin
 	 * being inactive most of the time.
 	 *
 	 * Here, we don't do that, and instead invert the polarity of the PWM
 	 * when it is active. This trick makes the PWM start with its active
 	 * state instead of its inactive state.
 	 */
 	if ((state->polarity == PWM_POLARITY_NORMAL) ^ state->enabled)
 		regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
 				   TCU_TCSR_PWM_INITL_HIGH, 0);
 	else
 		regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
 				   TCU_TCSR_PWM_INITL_HIGH,
 				   TCU_TCSR_PWM_INITL_HIGH);

 	if (state->enabled)
 		jz4740_pwm_enable(chip, pwm);

 	return 0;
 }

 static const struct pwm_ops jz4740_pwm_ops = {
 	.request = jz4740_pwm_request,
 	.free = jz4740_pwm_free,
 	.apply = jz4740_pwm_apply,
 	.owner = THIS_MODULE,
 };

 static int jz4740_pwm_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct jz4740_pwm_chip *jz4740;
 	const struct soc_info *info;

 	info = device_get_match_data(dev);
 	if (!info)
 		return -EINVAL;

 	jz4740 = devm_kzalloc(dev, sizeof(*jz4740), GFP_KERNEL);
 	if (!jz4740)
 		return -ENOMEM;

 	jz4740->map = device_node_to_regmap(dev->parent->of_node);
 	if (IS_ERR(jz4740->map)) {
 		dev_err(dev, "regmap not found: %ld\n", PTR_ERR(jz4740->map));
 		return PTR_ERR(jz4740->map);
 	}

 	jz4740->chip.dev = dev;
 	jz4740->chip.ops = &jz4740_pwm_ops;
 	jz4740->chip.npwm = info->num_pwms;

 	return devm_pwmchip_add(dev, &jz4740->chip);
 }

 static const struct soc_info __maybe_unused jz4740_soc_info = {
 	.num_pwms = 8,
 };

 static const struct soc_info __maybe_unused jz4725b_soc_info = {
 	.num_pwms = 6,
 };

 #ifdef CONFIG_OF
 static const struct of_device_id jz4740_pwm_dt_ids[] = {
 	{ .compatible = "ingenic,jz4740-pwm", .data = &jz4740_soc_info },
 	{ .compatible = "ingenic,jz4725b-pwm", .data = &jz4725b_soc_info },
 	{},
 };
 MODULE_DEVICE_TABLE(of, jz4740_pwm_dt_ids);
 #endif

 static struct platform_driver jz4740_pwm_driver = {
 	.driver = {
 		.name = "jz4740-pwm",
 		.of_match_table = of_match_ptr(jz4740_pwm_dt_ids),
 	},
 	.probe = jz4740_pwm_probe,
 };
 module_platform_driver(jz4740_pwm_driver);

 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
 MODULE_ALIAS("platform:jz4740-pwm");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
	* JZ4740 platform PWM support
	*
	* Limitations:
	* - The .apply callback doesn't complete the currently running period before
	* reconfiguring the hardware.
	*/

	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/gpio.h>
	#include <linux/kernel.h>
	#include <linux/mfd/ingenic-tcu.h>
	#include <linux/mfd/syscon.h>
	#include <linux/module.h>
	#include <linux/of_device.h>
	#include <linux/platform_device.h>
	#include <linux/pwm.h>
	#include <linux/regmap.h>

	struct soc_info {
	unsigned int num_pwms;
	};

	struct jz4740_pwm_chip {
	struct pwm_chip chip;
	struct regmap *map;
	};

	static inline struct jz4740_pwm_chip to_jz4740(struct pwm_chip chip)
	{
	return container_of(chip, struct jz4740_pwm_chip, chip);
	}

	static bool jz4740_pwm_can_use_chn(struct jz4740_pwm_chip *jz,
	unsigned int channel)
	{
	/* Enable all TCU channels for PWM use by default except channels 0/1 */
	u32 pwm_channels_mask = GENMASK(jz->chip.npwm - 1, 2);

	device_property_read_u32(jz->chip.dev->parent,
	"ingenic,pwm-channels-mask",
	&pwm_channels_mask);

	return !!(pwm_channels_mask & BIT(channel));
	}

	static int jz4740_pwm_request(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct jz4740_pwm_chip *jz = to_jz4740(chip);
	struct clk *clk;
	char name[16];
	int err;

	if (!jz4740_pwm_can_use_chn(jz, pwm->hwpwm))
	return -EBUSY;

	snprintf(name, sizeof(name), "timer%u", pwm->hwpwm);

	clk = clk_get(chip->dev, name);
	if (IS_ERR(clk))
	return dev_err_probe(chip->dev, PTR_ERR(clk),
	"Failed to get clock\n");

	err = clk_prepare_enable(clk);
	if (err < 0) {
	clk_put(clk);
	return err;
	}

	pwm_set_chip_data(pwm, clk);

	return 0;
	}

	static void jz4740_pwm_free(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct clk *clk = pwm_get_chip_data(pwm);

	clk_disable_unprepare(clk);
	clk_put(clk);
	}

	static int jz4740_pwm_enable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct jz4740_pwm_chip *jz = to_jz4740(chip);

	/* Enable PWM output */
	regmap_update_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
	TCU_TCSR_PWM_EN, TCU_TCSR_PWM_EN);

	/* Start counter */
	regmap_write(jz->map, TCU_REG_TESR, BIT(pwm->hwpwm));

	return 0;
	}

	static void jz4740_pwm_disable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct jz4740_pwm_chip *jz = to_jz4740(chip);

	/*
	* Set duty > period. This trick allows the TCU channels in TCU2 mode to
	* properly return to their init level.
	*/
	regmap_write(jz->map, TCU_REG_TDHRc(pwm->hwpwm), 0xffff);
	regmap_write(jz->map, TCU_REG_TDFRc(pwm->hwpwm), 0x0);

	/*
	* Disable PWM output.
	* In TCU2 mode (channel 1/2 on JZ4750+), this must be done before the
	* counter is stopped, while in TCU1 mode the order does not matter.
	*/
	regmap_update_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
	TCU_TCSR_PWM_EN, 0);

	/* Stop counter */
	regmap_write(jz->map, TCU_REG_TECR, BIT(pwm->hwpwm));
	}

	static int jz4740_pwm_apply(struct pwm_chip chip, struct pwm_device pwm,
	const struct pwm_state *state)
	{
	struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
	unsigned long long tmp = 0xffffull * NSEC_PER_SEC;
	struct clk *clk = pwm_get_chip_data(pwm);
	unsigned long period, duty;
	long rate;
	int err;

	/*
	* Limit the clock to a maximum rate that still gives us a period value
	* which fits in 16 bits.
	*/
	do_div(tmp, state->period);

	/*
	* /!\ IMPORTANT NOTE:
	* -------------------
	* This code relies on the fact that clk_round_rate() will always round
	* down, which is not a valid assumption given by the clk API, but only
	* happens to be true with the clk drivers used for Ingenic SoCs.
	*
	* Right now, there is no alternative as the clk API does not have a
	* round-down function (and won't have one for a while), but if it ever
	* comes to light, a round-down function should be used instead.
	*/
	rate = clk_round_rate(clk, tmp);
	if (rate < 0) {
	dev_err(chip->dev, "Unable to round rate: %ld", rate);
	return rate;
	}

	/* Calculate period value */
	tmp = (unsigned long long)rate * state->period;
	do_div(tmp, NSEC_PER_SEC);
	period = tmp;

	/* Calculate duty value */
	tmp = (unsigned long long)rate * state->duty_cycle;
	do_div(tmp, NSEC_PER_SEC);
	duty = tmp;

	if (duty >= period)
	duty = period - 1;

	jz4740_pwm_disable(chip, pwm);

	err = clk_set_rate(clk, rate);
	if (err) {
	dev_err(chip->dev, "Unable to set rate: %d", err);
	return err;
	}

	/* Reset counter to 0 */
	regmap_write(jz4740->map, TCU_REG_TCNTc(pwm->hwpwm), 0);

	/* Set duty */
	regmap_write(jz4740->map, TCU_REG_TDHRc(pwm->hwpwm), duty);

	/* Set period */
	regmap_write(jz4740->map, TCU_REG_TDFRc(pwm->hwpwm), period);

	/* Set abrupt shutdown */
	regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
	TCU_TCSR_PWM_SD, TCU_TCSR_PWM_SD);

	/*
	* Set polarity.
	*
	* The PWM starts in inactive state until the internal timer reaches the
	* duty value, then becomes active until the timer reaches the period
	* value. In theory, we should then use (period - duty) as the real duty
	* value, as a high duty value would otherwise result in the PWM pin
	* being inactive most of the time.
	*
	* Here, we don't do that, and instead invert the polarity of the PWM
	* when it is active. This trick makes the PWM start with its active
	* state instead of its inactive state.
	*/
	if ((state->polarity == PWM_POLARITY_NORMAL) ^ state->enabled)
	regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
	TCU_TCSR_PWM_INITL_HIGH, 0);
	else
	regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
	TCU_TCSR_PWM_INITL_HIGH,
	TCU_TCSR_PWM_INITL_HIGH);

	if (state->enabled)
	jz4740_pwm_enable(chip, pwm);

	return 0;
	}

	static const struct pwm_ops jz4740_pwm_ops = {
	.request = jz4740_pwm_request,
	.free = jz4740_pwm_free,
	.apply = jz4740_pwm_apply,
	.owner = THIS_MODULE,
	};

	static int jz4740_pwm_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct jz4740_pwm_chip *jz4740;
	const struct soc_info *info;

	info = device_get_match_data(dev);
	if (!info)
	return -EINVAL;

	jz4740 = devm_kzalloc(dev, sizeof(*jz4740), GFP_KERNEL);
	if (!jz4740)
	return -ENOMEM;

	jz4740->map = device_node_to_regmap(dev->parent->of_node);
	if (IS_ERR(jz4740->map)) {
	dev_err(dev, "regmap not found: %ld\n", PTR_ERR(jz4740->map));
	return PTR_ERR(jz4740->map);
	}

	jz4740->chip.dev = dev;
	jz4740->chip.ops = &jz4740_pwm_ops;
	jz4740->chip.npwm = info->num_pwms;

	return devm_pwmchip_add(dev, &jz4740->chip);
	}

	static const struct soc_info __maybe_unused jz4740_soc_info = {
	.num_pwms = 8,
	};

	static const struct soc_info __maybe_unused jz4725b_soc_info = {
	.num_pwms = 6,
	};

	#ifdef CONFIG_OF
	static const struct of_device_id jz4740_pwm_dt_ids[] = {
	{ .compatible = "ingenic,jz4740-pwm", .data = &jz4740_soc_info },
	{ .compatible = "ingenic,jz4725b-pwm", .data = &jz4725b_soc_info },
	{},
	};
	MODULE_DEVICE_TABLE(of, jz4740_pwm_dt_ids);
	#endif

	static struct platform_driver jz4740_pwm_driver = {
	.driver = {
	.name = "jz4740-pwm",
	.of_match_table = of_match_ptr(jz4740_pwm_dt_ids),
	},
	.probe = jz4740_pwm_probe,
	};
	module_platform_driver(jz4740_pwm_driver);

	MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
	MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
	MODULE_ALIAS("platform:jz4740-pwm");
	MODULE_LICENSE("GPL");