1 // SPDX-License-Identifier: GPL-2.0-only
3  * Generic software PWM for modulating GPIOs
15 #include <linux/gpio/consumer.h>
22 #include <linux/pwm.h>
29 	struct gpio_desc *gpio;  member
49 	dividend = dest->period;  in pwm_gpio_round()
51 	dest->period -= remainder;  in pwm_gpio_round()
53 	dividend = dest->duty_cycle;  in pwm_gpio_round()
55 	dest->duty_cycle -= remainder;  in pwm_gpio_round()
60 	const struct pwm_state *state = &gpwm->state;  in pwm_gpio_toggle()
61 	bool invert = state->polarity == PWM_POLARITY_INVERSED;  in pwm_gpio_toggle()
63 	gpwm->level = level;  in pwm_gpio_toggle()
64 	gpiod_set_value(gpwm->gpio, gpwm->level ^ invert);  in pwm_gpio_toggle()
66 	if (!state->duty_cycle || state->duty_cycle == state->period) {  in pwm_gpio_toggle()
67 		gpwm->running = false;  in pwm_gpio_toggle()
71 	gpwm->running = true;  in pwm_gpio_toggle()
72 	return level ? state->duty_cycle : state->period - state->duty_cycle;  in pwm_gpio_toggle()
82 	guard(spinlock_irqsave)(&gpwm->lock);  in pwm_gpio_timer()
85 	if (!gpwm->level && gpwm->changing) {  in pwm_gpio_timer()
86 		gpwm->changing = false;  in pwm_gpio_timer()
87 		gpwm->state = gpwm->next_state;  in pwm_gpio_timer()
88 		new_level = !!gpwm->state.duty_cycle;  in pwm_gpio_timer()
90 		new_level = !gpwm->level;  in pwm_gpio_timer()
101 static int pwm_gpio_apply(struct pwm_chip *chip, struct pwm_device *pwm,  in pwm_gpio_apply()  argument
105 	bool invert = state->polarity == PWM_POLARITY_INVERSED;  in pwm_gpio_apply()
107 	if (state->duty_cycle && state->duty_cycle < hrtimer_resolution)  in pwm_gpio_apply()
108 		return -EINVAL;  in pwm_gpio_apply()
110 	if (state->duty_cycle != state->period &&  in pwm_gpio_apply()
111 	    (state->period - state->duty_cycle < hrtimer_resolution))  in pwm_gpio_apply()
112 		return -EINVAL;  in pwm_gpio_apply()
114 	if (!state->enabled) {  in pwm_gpio_apply()
115 		hrtimer_cancel(&gpwm->gpio_timer);  in pwm_gpio_apply()
116 	} else if (!gpwm->running) {  in pwm_gpio_apply()
123 		ret = gpiod_direction_output(gpwm->gpio, invert);  in pwm_gpio_apply()
128 	guard(spinlock_irqsave)(&gpwm->lock);  in pwm_gpio_apply()
130 	if (!state->enabled) {  in pwm_gpio_apply()
131 		pwm_gpio_round(&gpwm->state, state);  in pwm_gpio_apply()
132 		gpwm->running = false;  in pwm_gpio_apply()
133 		gpwm->changing = false;  in pwm_gpio_apply()
135 		gpiod_set_value(gpwm->gpio, invert);  in pwm_gpio_apply()
136 	} else if (gpwm->running) {  in pwm_gpio_apply()
137 		pwm_gpio_round(&gpwm->next_state, state);  in pwm_gpio_apply()
138 		gpwm->changing = true;  in pwm_gpio_apply()
142 		pwm_gpio_round(&gpwm->state, state);  in pwm_gpio_apply()
143 		gpwm->changing = false;  in pwm_gpio_apply()
145 		next_toggle = pwm_gpio_toggle(gpwm, !!state->duty_cycle);  in pwm_gpio_apply()
147 			hrtimer_start(&gpwm->gpio_timer, next_toggle,  in pwm_gpio_apply()
154 static int pwm_gpio_get_state(struct pwm_chip *chip, struct pwm_device *pwm,  in pwm_gpio_get_state()  argument
159 	guard(spinlock_irqsave)(&gpwm->lock);  in pwm_gpio_get_state()
161 	if (gpwm->changing)  in pwm_gpio_get_state()
162 		*state = gpwm->next_state;  in pwm_gpio_get_state()
164 		*state = gpwm->state;  in pwm_gpio_get_state()
178 	hrtimer_cancel(&gpwm->gpio_timer);  in pwm_gpio_disable_hrtimer()
183 	struct device *dev = &pdev->dev;  in pwm_gpio_probe()
194 	spin_lock_init(&gpwm->lock);  in pwm_gpio_probe()
196 	gpwm->gpio = devm_gpiod_get(dev, NULL, GPIOD_ASIS);  in pwm_gpio_probe()
197 	if (IS_ERR(gpwm->gpio))  in pwm_gpio_probe()
198 		return dev_err_probe(dev, PTR_ERR(gpwm->gpio),  in pwm_gpio_probe()
199 				     "%pfw: could not get gpio\n",  in pwm_gpio_probe()
202 	if (gpiod_cansleep(gpwm->gpio))  in pwm_gpio_probe()
203 		return dev_err_probe(dev, -EINVAL,  in pwm_gpio_probe()
204 				     "%pfw: sleeping GPIO not supported\n",  in pwm_gpio_probe()
207 	chip->ops = &pwm_gpio_ops;  in pwm_gpio_probe()
208 	chip->atomic = true;  in pwm_gpio_probe()
210 	hrtimer_init(&gpwm->gpio_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);  in pwm_gpio_probe()
215 	gpwm->gpio_timer.function = pwm_gpio_timer;  in pwm_gpio_probe()
225 	{ .compatible = "pwm-gpio" },
232 		.name = "pwm-gpio",
239 MODULE_DESCRIPTION("PWM GPIO driver");