[mirror_ubuntu-jammy-kernel.git] / drivers / pwm / pwm-iqs620a.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Azoteq IQS620A PWM Generator
 *
 * Copyright (C) 2019 Jeff LaBundy <jeff@labundy.com>
 *
 * Limitations:
 * - The period is fixed to 1 ms and is generated continuously despite changes
 *   to the duty cycle or enable/disable state.
 * - Changes to the duty cycle or enable/disable state take effect immediately
 *   and may result in a glitch during the period in which the change is made.
 * - The device cannot generate a 0% duty cycle. For duty cycles below 1 / 256
 *   ms, the output is disabled and relies upon an external pull-down resistor
 *   to hold the GPIO3/LTX pin low.
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/mfd/iqs62x.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/regmap.h>
#include <linux/slab.h>

#define IQS620_PWR_SETTINGS			0xd2
#define IQS620_PWR_SETTINGS_PWM_OUT		BIT(7)

#define IQS620_PWM_DUTY_CYCLE			0xd8

#define IQS620_PWM_PERIOD_NS			1000000

struct iqs620_pwm_private {
	struct iqs62x_core *iqs62x;
	struct pwm_chip chip;
	struct notifier_block notifier;
	struct mutex lock;
	bool out_en;
	u8 duty_val;
};

static int iqs620_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
			    const struct pwm_state *state)
{
	struct iqs620_pwm_private *iqs620_pwm;
	struct iqs62x_core *iqs62x;
	unsigned int duty_cycle;
	unsigned int duty_scale;
	int ret;

	if (state->polarity != PWM_POLARITY_NORMAL)
		return -EINVAL;

	if (state->period < IQS620_PWM_PERIOD_NS)
		return -EINVAL;

	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
	iqs62x = iqs620_pwm->iqs62x;

	/*
	 * The duty cycle generated by the device is calculated as follows:
	 *
	 * duty_cycle = (IQS620_PWM_DUTY_CYCLE + 1) / 256 * 1 ms
	 *
	 * ...where IQS620_PWM_DUTY_CYCLE is a register value between 0 and 255
	 * (inclusive). Therefore the lowest duty cycle the device can generate
	 * while the output is enabled is 1 / 256 ms.
	 *
	 * For lower duty cycles (e.g. 0), the PWM output is simply disabled to
	 * allow an external pull-down resistor to hold the GPIO3/LTX pin low.
	 */
	duty_cycle = min_t(u64, state->duty_cycle, IQS620_PWM_PERIOD_NS);
	duty_scale = duty_cycle * 256 / IQS620_PWM_PERIOD_NS;

	mutex_lock(&iqs620_pwm->lock);

	if (!state->enabled || !duty_scale) {
		ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
					 IQS620_PWR_SETTINGS_PWM_OUT, 0);
		if (ret)
			goto err_mutex;
	}

	if (duty_scale) {
		u8 duty_val = duty_scale - 1;

		ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
				   duty_val);
		if (ret)
			goto err_mutex;

		iqs620_pwm->duty_val = duty_val;
	}

	if (state->enabled && duty_scale) {
		ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
					 IQS620_PWR_SETTINGS_PWM_OUT, 0xff);
		if (ret)
			goto err_mutex;
	}

	iqs620_pwm->out_en = state->enabled;

err_mutex:
	mutex_unlock(&iqs620_pwm->lock);

	return ret;
}

static void iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
				 struct pwm_state *state)
{
	struct iqs620_pwm_private *iqs620_pwm;

	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);

	mutex_lock(&iqs620_pwm->lock);

	/*
	 * Since the device cannot generate a 0% duty cycle, requests to do so
	 * cause subsequent calls to iqs620_pwm_get_state to report the output
	 * as disabled with duty cycle equal to that which was in use prior to
	 * the request. This is not ideal, but is the best compromise based on
	 * the capabilities of the device.
	 */
	state->enabled = iqs620_pwm->out_en;
	state->duty_cycle = DIV_ROUND_UP((iqs620_pwm->duty_val + 1) *
					 IQS620_PWM_PERIOD_NS, 256);

	mutex_unlock(&iqs620_pwm->lock);

	state->period = IQS620_PWM_PERIOD_NS;
}

static int iqs620_pwm_notifier(struct notifier_block *notifier,
			       unsigned long event_flags, void *context)
{
	struct iqs620_pwm_private *iqs620_pwm;
	struct iqs62x_core *iqs62x;
	int ret;

	if (!(event_flags & BIT(IQS62X_EVENT_SYS_RESET)))
		return NOTIFY_DONE;

	iqs620_pwm = container_of(notifier, struct iqs620_pwm_private,
				  notifier);
	iqs62x = iqs620_pwm->iqs62x;

	mutex_lock(&iqs620_pwm->lock);

	/*
	 * The parent MFD driver already prints an error message in the event
	 * of a device reset, so nothing else is printed here unless there is
	 * an additional failure.
	 */
	ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
			   iqs620_pwm->duty_val);
	if (ret)
		goto err_mutex;

	ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
				 IQS620_PWR_SETTINGS_PWM_OUT,
				 iqs620_pwm->out_en ? 0xff : 0);

err_mutex:
	mutex_unlock(&iqs620_pwm->lock);

	if (ret) {
		dev_err(iqs620_pwm->chip.dev,
			"Failed to re-initialize device: %d\n", ret);
		return NOTIFY_BAD;
	}

	return NOTIFY_OK;
}

static const struct pwm_ops iqs620_pwm_ops = {
	.apply = iqs620_pwm_apply,
	.get_state = iqs620_pwm_get_state,
	.owner = THIS_MODULE,
};

static void iqs620_pwm_notifier_unregister(void *context)
{
	struct iqs620_pwm_private *iqs620_pwm = context;
	int ret;

	ret = blocking_notifier_chain_unregister(&iqs620_pwm->iqs62x->nh,
						 &iqs620_pwm->notifier);
	if (ret)
		dev_err(iqs620_pwm->chip.dev,
			"Failed to unregister notifier: %d\n", ret);
}

static int iqs620_pwm_probe(struct platform_device *pdev)
{
	struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
	struct iqs620_pwm_private *iqs620_pwm;
	unsigned int val;
	int ret;

	iqs620_pwm = devm_kzalloc(&pdev->dev, sizeof(*iqs620_pwm), GFP_KERNEL);
	if (!iqs620_pwm)
		return -ENOMEM;

	platform_set_drvdata(pdev, iqs620_pwm);
	iqs620_pwm->iqs62x = iqs62x;

	ret = regmap_read(iqs62x->regmap, IQS620_PWR_SETTINGS, &val);
	if (ret)
		return ret;
	iqs620_pwm->out_en = val & IQS620_PWR_SETTINGS_PWM_OUT;

	ret = regmap_read(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, &val);
	if (ret)
		return ret;
	iqs620_pwm->duty_val = val;

	iqs620_pwm->chip.dev = &pdev->dev;
	iqs620_pwm->chip.ops = &iqs620_pwm_ops;
	iqs620_pwm->chip.base = -1;
	iqs620_pwm->chip.npwm = 1;

	mutex_init(&iqs620_pwm->lock);

	iqs620_pwm->notifier.notifier_call = iqs620_pwm_notifier;
	ret = blocking_notifier_chain_register(&iqs620_pwm->iqs62x->nh,
					       &iqs620_pwm->notifier);
	if (ret) {
		dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
		return ret;
	}

	ret = devm_add_action_or_reset(&pdev->dev,
				       iqs620_pwm_notifier_unregister,
				       iqs620_pwm);
	if (ret)
		return ret;

	ret = pwmchip_add(&iqs620_pwm->chip);
	if (ret)
		dev_err(&pdev->dev, "Failed to add device: %d\n", ret);

	return ret;
}

static int iqs620_pwm_remove(struct platform_device *pdev)
{
	struct iqs620_pwm_private *iqs620_pwm = platform_get_drvdata(pdev);
	int ret;

	ret = pwmchip_remove(&iqs620_pwm->chip);
	if (ret)
		dev_err(&pdev->dev, "Failed to remove device: %d\n", ret);

	return ret;
}

static struct platform_driver iqs620_pwm_platform_driver = {
	.driver = {
		.name = "iqs620a-pwm",
	},
	.probe = iqs620_pwm_probe,
	.remove = iqs620_pwm_remove,
};
module_platform_driver(iqs620_pwm_platform_driver);

MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
MODULE_DESCRIPTION("Azoteq IQS620A PWM Generator");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:iqs620a-pwm");
Commit	Line	Data
6f0841a8 JL	1	// SPDX-License-Identifier: GPL-2.0+
	2	/*
	3	* Azoteq IQS620A PWM Generator
	4	*
	5	* Copyright (C) 2019 Jeff LaBundy <jeff@labundy.com>
	6	*
	7	* Limitations:
	8	* - The period is fixed to 1 ms and is generated continuously despite changes
	9	* to the duty cycle or enable/disable state.
	10	* - Changes to the duty cycle or enable/disable state take effect immediately
	11	* and may result in a glitch during the period in which the change is made.
	12	* - The device cannot generate a 0% duty cycle. For duty cycles below 1 / 256
	13	* ms, the output is disabled and relies upon an external pull-down resistor
	14	* to hold the GPIO3/LTX pin low.
	15	*/
	16
	17	#include <linux/device.h>
	18	#include <linux/kernel.h>
	19	#include <linux/mfd/iqs62x.h>
	20	#include <linux/module.h>
	21	#include <linux/mutex.h>
	22	#include <linux/notifier.h>
	23	#include <linux/platform_device.h>
	24	#include <linux/pwm.h>
	25	#include <linux/regmap.h>
	26	#include <linux/slab.h>
	27
b8fb642a	28	#define IQS620_PWR_SETTINGS 0xd2
6f0841a8 JL	29	#define IQS620_PWR_SETTINGS_PWM_OUT BIT(7)
6f0841a8 JL	30
b8fb642a	31	#define IQS620_PWM_DUTY_CYCLE 0xd8
6f0841a8 JL	32
	33	#define IQS620_PWM_PERIOD_NS 1000000
	34
	35	struct iqs620_pwm_private {
	36	struct iqs62x_core *iqs62x;
	37	struct pwm_chip chip;
	38	struct notifier_block notifier;
	39	struct mutex lock;
	40	bool out_en;
	41	u8 duty_val;
	42	};
	43
	44	static int iqs620_pwm_apply(struct pwm_chip chip, struct pwm_device pwm,
	45	const struct pwm_state *state)
	46	{
	47	struct iqs620_pwm_private *iqs620_pwm;
	48	struct iqs62x_core *iqs62x;
72d6b245 UKK	49	unsigned int duty_cycle;
72d6b245 UKK	50	unsigned int duty_scale;
5bc5d99f	51	int ret;
6f0841a8 JL	52
6f0841a8 JL	53	if (state->polarity != PWM_POLARITY_NORMAL)
2b1c1a5d	54	return -EINVAL;
6f0841a8 JL	55
	56	if (state->period < IQS620_PWM_PERIOD_NS)
	57	return -EINVAL;
	58
	59	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
	60	iqs62x = iqs620_pwm->iqs62x;
	61
	62	/*
	63	* The duty cycle generated by the device is calculated as follows:
	64	*
	65	* duty_cycle = (IQS620_PWM_DUTY_CYCLE + 1) / 256 * 1 ms
	66	*
	67	* ...where IQS620_PWM_DUTY_CYCLE is a register value between 0 and 255
	68	* (inclusive). Therefore the lowest duty cycle the device can generate
	69	* while the output is enabled is 1 / 256 ms.
	70	*
	71	* For lower duty cycles (e.g. 0), the PWM output is simply disabled to
	72	* allow an external pull-down resistor to hold the GPIO3/LTX pin low.
	73	*/
72d6b245 UKK	74	duty_cycle = min_t(u64, state->duty_cycle, IQS620_PWM_PERIOD_NS);
72d6b245 UKK	75	duty_scale = duty_cycle * 256 / IQS620_PWM_PERIOD_NS;
6f0841a8 JL	76
	77	mutex_lock(&iqs620_pwm->lock);
	78
	79	if (!state->enabled \|\| !duty_scale) {
	80	ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
	81	IQS620_PWR_SETTINGS_PWM_OUT, 0);
	82	if (ret)
	83	goto err_mutex;
	84	}
	85
	86	if (duty_scale) {
72d6b245	87	u8 duty_val = duty_scale - 1;
6f0841a8 JL	88
	89	ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
	90	duty_val);
	91	if (ret)
	92	goto err_mutex;
	93
	94	iqs620_pwm->duty_val = duty_val;
	95	}
	96
	97	if (state->enabled && duty_scale) {
	98	ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
b8fb642a	99	IQS620_PWR_SETTINGS_PWM_OUT, 0xff);
6f0841a8 JL	100	if (ret)
	101	goto err_mutex;
	102	}
	103
	104	iqs620_pwm->out_en = state->enabled;
	105
	106	err_mutex:
	107	mutex_unlock(&iqs620_pwm->lock);
	108
	109	return ret;
	110	}
	111
	112	static void iqs620_pwm_get_state(struct pwm_chip chip, struct pwm_device pwm,
	113	struct pwm_state *state)
	114	{
	115	struct iqs620_pwm_private *iqs620_pwm;
	116
	117	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
	118
	119	mutex_lock(&iqs620_pwm->lock);
	120
	121	/*
	122	* Since the device cannot generate a 0% duty cycle, requests to do so
	123	* cause subsequent calls to iqs620_pwm_get_state to report the output
	124	* as disabled with duty cycle equal to that which was in use prior to
	125	* the request. This is not ideal, but is the best compromise based on
	126	* the capabilities of the device.
	127	*/
	128	state->enabled = iqs620_pwm->out_en;
	129	state->duty_cycle = DIV_ROUND_UP((iqs620_pwm->duty_val + 1) *
	130	IQS620_PWM_PERIOD_NS, 256);
	131
	132	mutex_unlock(&iqs620_pwm->lock);
	133
	134	state->period = IQS620_PWM_PERIOD_NS;
	135	}
	136
	137	static int iqs620_pwm_notifier(struct notifier_block *notifier,
	138	unsigned long event_flags, void *context)
	139	{
	140	struct iqs620_pwm_private *iqs620_pwm;
	141	struct iqs62x_core *iqs62x;
	142	int ret;
	143
	144	if (!(event_flags & BIT(IQS62X_EVENT_SYS_RESET)))
	145	return NOTIFY_DONE;
	146
	147	iqs620_pwm = container_of(notifier, struct iqs620_pwm_private,
	148	notifier);
	149	iqs62x = iqs620_pwm->iqs62x;
	150
	151	mutex_lock(&iqs620_pwm->lock);
	152
	153	/*
	154	* The parent MFD driver already prints an error message in the event
	155	* of a device reset, so nothing else is printed here unless there is
	156	* an additional failure.
	157	*/
	158	ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
	159	iqs620_pwm->duty_val);
	160	if (ret)
	161	goto err_mutex;
	162
	163	ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
164	IQS620_PWR_SETTINGS_PWM_OUT,
b8fb642a	165	iqs620_pwm->out_en ? 0xff : 0);
6f0841a8 JL	166
	167	err_mutex:
	168	mutex_unlock(&iqs620_pwm->lock);
	169
	170	if (ret) {
	171	dev_err(iqs620_pwm->chip.dev,
	172	"Failed to re-initialize device: %d\n", ret);
	173	return NOTIFY_BAD;
	174	}
	175
	176	return NOTIFY_OK;
	177	}
	178
	179	static const struct pwm_ops iqs620_pwm_ops = {
	180	.apply = iqs620_pwm_apply,
	181	.get_state = iqs620_pwm_get_state,
	182	.owner = THIS_MODULE,
	183	};
	184
	185	static void iqs620_pwm_notifier_unregister(void *context)
	186	{
	187	struct iqs620_pwm_private *iqs620_pwm = context;
	188	int ret;
	189
	190	ret = blocking_notifier_chain_unregister(&iqs620_pwm->iqs62x->nh,
	191	&iqs620_pwm->notifier);
	192	if (ret)
	193	dev_err(iqs620_pwm->chip.dev,
	194	"Failed to unregister notifier: %d\n", ret);
	195	}
	196
	197	static int iqs620_pwm_probe(struct platform_device *pdev)
	198	{
	199	struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
	200	struct iqs620_pwm_private *iqs620_pwm;
	201	unsigned int val;
	202	int ret;
	203
	204	iqs620_pwm = devm_kzalloc(&pdev->dev, sizeof(*iqs620_pwm), GFP_KERNEL);
	205	if (!iqs620_pwm)
	206	return -ENOMEM;
	207
	208	platform_set_drvdata(pdev, iqs620_pwm);
	209	iqs620_pwm->iqs62x = iqs62x;
	210
	211	ret = regmap_read(iqs62x->regmap, IQS620_PWR_SETTINGS, &val);
	212	if (ret)
	213	return ret;
	214	iqs620_pwm->out_en = val & IQS620_PWR_SETTINGS_PWM_OUT;
	215
	216	ret = regmap_read(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, &val);
	217	if (ret)
	218	return ret;
	219	iqs620_pwm->duty_val = val;
	220
	221	iqs620_pwm->chip.dev = &pdev->dev;
	222	iqs620_pwm->chip.ops = &iqs620_pwm_ops;
	223	iqs620_pwm->chip.base = -1;
	224	iqs620_pwm->chip.npwm = 1;
	225
	226	mutex_init(&iqs620_pwm->lock);
	227
	228	iqs620_pwm->notifier.notifier_call = iqs620_pwm_notifier;
	229	ret = blocking_notifier_chain_register(&iqs620_pwm->iqs62x->nh,
230	&iqs620_pwm->notifier);
231	if (ret) {
232	dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
233	return ret;
234	}
235
236	ret = devm_add_action_or_reset(&pdev->dev,
237	iqs620_pwm_notifier_unregister,
238	iqs620_pwm);
239	if (ret)
240	return ret;
241
242	ret = pwmchip_add(&iqs620_pwm->chip);
243	if (ret)
244	dev_err(&pdev->dev, "Failed to add device: %d\n", ret);
245
246	return ret;
247	}
248
249	static int iqs620_pwm_remove(struct platform_device *pdev)
250	{
251	struct iqs620_pwm_private *iqs620_pwm = platform_get_drvdata(pdev);
252	int ret;
253
254	ret = pwmchip_remove(&iqs620_pwm->chip);
255	if (ret)
256	dev_err(&pdev->dev, "Failed to remove device: %d\n", ret);
257
258	return ret;
259	}
260
261	static struct platform_driver iqs620_pwm_platform_driver = {
262	.driver = {
263	.name = "iqs620a-pwm",
264	},
265	.probe = iqs620_pwm_probe,
266	.remove = iqs620_pwm_remove,
267	};
268	module_platform_driver(iqs620_pwm_platform_driver);
269
270	MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
271	MODULE_DESCRIPTION("Azoteq IQS620A PWM Generator");
272	MODULE_LICENSE("GPL");
273	MODULE_ALIAS("platform:iqs620a-pwm");