[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;
	int duty_scale, ret;

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

	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_scale = state->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 = min(duty_scale - 1, 0xFF);

		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
	28	#define IQS620_PWR_SETTINGS 0xD2
	29	#define IQS620_PWR_SETTINGS_PWM_OUT BIT(7)
	30
	31	#define IQS620_PWM_DUTY_CYCLE 0xD8
	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;
	49	int duty_scale, ret;
	50
	51	if (state->polarity != PWM_POLARITY_NORMAL)
	52	return -ENOTSUPP;
	53
	54	if (state->period < IQS620_PWM_PERIOD_NS)
	55	return -EINVAL;
	56
	57	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
	58	iqs62x = iqs620_pwm->iqs62x;
	59
	60	/*
	61	* The duty cycle generated by the device is calculated as follows:
	62	*
	63	* duty_cycle = (IQS620_PWM_DUTY_CYCLE + 1) / 256 * 1 ms
	64	*
65	* ...where IQS620_PWM_DUTY_CYCLE is a register value between 0 and 255
66	* (inclusive). Therefore the lowest duty cycle the device can generate
67	* while the output is enabled is 1 / 256 ms.
68	*
69	* For lower duty cycles (e.g. 0), the PWM output is simply disabled to
70	* allow an external pull-down resistor to hold the GPIO3/LTX pin low.
71	*/
72	duty_scale = state->duty_cycle * 256 / IQS620_PWM_PERIOD_NS;
73
74	mutex_lock(&iqs620_pwm->lock);
75
76	if (!state->enabled \|\| !duty_scale) {
77	ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
78	IQS620_PWR_SETTINGS_PWM_OUT, 0);
79	if (ret)
80	goto err_mutex;
81	}
82
83	if (duty_scale) {
84	u8 duty_val = min(duty_scale - 1, 0xFF);
85
86	ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
87	duty_val);
88	if (ret)
89	goto err_mutex;
90
91	iqs620_pwm->duty_val = duty_val;
92	}
93
94	if (state->enabled && duty_scale) {
95	ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
96	IQS620_PWR_SETTINGS_PWM_OUT, 0xFF);
97	if (ret)
98	goto err_mutex;
99	}
100
101	iqs620_pwm->out_en = state->enabled;
102
103	err_mutex:
104	mutex_unlock(&iqs620_pwm->lock);
105
106	return ret;
107	}
108
109	static void iqs620_pwm_get_state(struct pwm_chip chip, struct pwm_device pwm,
110	struct pwm_state *state)
111	{
112	struct iqs620_pwm_private *iqs620_pwm;
113
114	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
115
116	mutex_lock(&iqs620_pwm->lock);
117
118	/*
119	* Since the device cannot generate a 0% duty cycle, requests to do so
120	* cause subsequent calls to iqs620_pwm_get_state to report the output
121	* as disabled with duty cycle equal to that which was in use prior to
122	* the request. This is not ideal, but is the best compromise based on
123	* the capabilities of the device.
124	*/
125	state->enabled = iqs620_pwm->out_en;
126	state->duty_cycle = DIV_ROUND_UP((iqs620_pwm->duty_val + 1) *
127	IQS620_PWM_PERIOD_NS, 256);
128
129	mutex_unlock(&iqs620_pwm->lock);
130
131	state->period = IQS620_PWM_PERIOD_NS;
132	}
133
134	static int iqs620_pwm_notifier(struct notifier_block *notifier,
135	unsigned long event_flags, void *context)
136	{
137	struct iqs620_pwm_private *iqs620_pwm;
138	struct iqs62x_core *iqs62x;
139	int ret;
140
141	if (!(event_flags & BIT(IQS62X_EVENT_SYS_RESET)))
142	return NOTIFY_DONE;
143
144	iqs620_pwm = container_of(notifier, struct iqs620_pwm_private,
145	notifier);
146	iqs62x = iqs620_pwm->iqs62x;
147
148	mutex_lock(&iqs620_pwm->lock);
149
150	/*
151	* The parent MFD driver already prints an error message in the event
152	* of a device reset, so nothing else is printed here unless there is
153	* an additional failure.
154	*/
155	ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
156	iqs620_pwm->duty_val);
157	if (ret)
158	goto err_mutex;
159
160	ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
161	IQS620_PWR_SETTINGS_PWM_OUT,
162	iqs620_pwm->out_en ? 0xFF : 0);
163
164	err_mutex:
165	mutex_unlock(&iqs620_pwm->lock);
166
167	if (ret) {
168	dev_err(iqs620_pwm->chip.dev,
169	"Failed to re-initialize device: %d\n", ret);
170	return NOTIFY_BAD;
171	}
172
173	return NOTIFY_OK;
174	}
175
176	static const struct pwm_ops iqs620_pwm_ops = {
177	.apply = iqs620_pwm_apply,
178	.get_state = iqs620_pwm_get_state,
179	.owner = THIS_MODULE,
180	};
181
182	static void iqs620_pwm_notifier_unregister(void *context)
183	{
184	struct iqs620_pwm_private *iqs620_pwm = context;
185	int ret;
186
187	ret = blocking_notifier_chain_unregister(&iqs620_pwm->iqs62x->nh,
188	&iqs620_pwm->notifier);
189	if (ret)
190	dev_err(iqs620_pwm->chip.dev,
191	"Failed to unregister notifier: %d\n", ret);
192	}
193
194	static int iqs620_pwm_probe(struct platform_device *pdev)
195	{
196	struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
197	struct iqs620_pwm_private *iqs620_pwm;
198	unsigned int val;
199	int ret;
200
201	iqs620_pwm = devm_kzalloc(&pdev->dev, sizeof(*iqs620_pwm), GFP_KERNEL);
202	if (!iqs620_pwm)
203	return -ENOMEM;
204
205	platform_set_drvdata(pdev, iqs620_pwm);
206	iqs620_pwm->iqs62x = iqs62x;
207
208	ret = regmap_read(iqs62x->regmap, IQS620_PWR_SETTINGS, &val);
209	if (ret)
210	return ret;
211	iqs620_pwm->out_en = val & IQS620_PWR_SETTINGS_PWM_OUT;
212
213	ret = regmap_read(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, &val);
214	if (ret)
215	return ret;
216	iqs620_pwm->duty_val = val;
217
218	iqs620_pwm->chip.dev = &pdev->dev;
219	iqs620_pwm->chip.ops = &iqs620_pwm_ops;
220	iqs620_pwm->chip.base = -1;
221	iqs620_pwm->chip.npwm = 1;
222
223	mutex_init(&iqs620_pwm->lock);
224
225	iqs620_pwm->notifier.notifier_call = iqs620_pwm_notifier;
226	ret = blocking_notifier_chain_register(&iqs620_pwm->iqs62x->nh,
227	&iqs620_pwm->notifier);
228	if (ret) {
229	dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
230	return ret;
231	}
232
233	ret = devm_add_action_or_reset(&pdev->dev,
234	iqs620_pwm_notifier_unregister,
235	iqs620_pwm);
236	if (ret)
237	return ret;
238
239	ret = pwmchip_add(&iqs620_pwm->chip);
240	if (ret)
241	dev_err(&pdev->dev, "Failed to add device: %d\n", ret);
242
243	return ret;
244	}
245
246	static int iqs620_pwm_remove(struct platform_device *pdev)
247	{
248	struct iqs620_pwm_private *iqs620_pwm = platform_get_drvdata(pdev);
249	int ret;
250
251	ret = pwmchip_remove(&iqs620_pwm->chip);
252	if (ret)
253	dev_err(&pdev->dev, "Failed to remove device: %d\n", ret);
254
255	return ret;
256	}
257
258	static struct platform_driver iqs620_pwm_platform_driver = {
259	.driver = {
260	.name = "iqs620a-pwm",
261	},
262	.probe = iqs620_pwm_probe,
263	.remove = iqs620_pwm_remove,
264	};
265	module_platform_driver(iqs620_pwm_platform_driver);
266
267	MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
268	MODULE_DESCRIPTION("Azoteq IQS620A PWM Generator");
269	MODULE_LICENSE("GPL");
270	MODULE_ALIAS("platform:iqs620a-pwm");