1 // SPDX-License-Identifier: GPL-2.0-only
3  * Activity LED trigger
6  * Partially based on Atsushi Nemoto's ledtrig-heartbeat.c.
36 	struct led_classdev *led_cdev = activity_data->led_cdev;  in led_activity_function()
47 	if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))  in led_activity_function()
48 		led_cdev->blink_brightness = led_cdev->new_blink_brightness;  in led_activity_function()
52 		led_set_brightness_nosleep(led_cdev, led_cdev->blink_brightness);  in led_activity_function()
74 	 * down to 16us, ensuring we won't overflow 32-bit computations below  in led_activity_function()
78 	diff_boot = (curr_boot - activity_data->last_boot) >> 16;  in led_activity_function()
79 	diff_used = (curr_used - activity_data->last_used) >> 16;  in led_activity_function()
80 	activity_data->last_boot = curr_boot;  in led_activity_function()
81 	activity_data->last_used = curr_used;  in led_activity_function()
95 	 *      1 - delta_idle / delta_boot  in led_activity_function()
97 	 * What we want is that when the CPU usage is zero, the LED must blink  in led_activity_function()
101 	 * enough to saturate one core in multi-core systems or 50% in single  in led_activity_function()
106 	 * all cores are saturated. It's important that the LED never stays in  in led_activity_function()
111 	 *   - a target CPU usage of min(50%, 100%/#CPU) for a 10% duty cycle  in led_activity_function()
113 	 *   - below target :  in led_activity_function()
115 	 *      OFF_ms = 90 + (1 - usage/target) * 900  in led_activity_function()
116 	 *   - above target :  in led_activity_function()
117 	 *      ON_ms  = 10 + (usage-target)/(100%-target) * 80  in led_activity_function()
118 	 *      OFF_ms = 90 - (usage-target)/(100%-target) * 80  in led_activity_function()
125 	activity_data->time_left -= 100;  in led_activity_function()
126 	if (activity_data->time_left <= 0) {  in led_activity_function()
127 		activity_data->time_left = 0;  in led_activity_function()
128 		activity_data->state = !activity_data->state;  in led_activity_function()
130 			(activity_data->state ^ activity_data->invert) ?  in led_activity_function()
131 			led_cdev->blink_brightness : LED_OFF);  in led_activity_function()
137 		delay = activity_data->state ?  in led_activity_function()
139 			990 - 900 * usage / target; /* OFF */  in led_activity_function()
141 		delay = activity_data->state ?  in led_activity_function()
142 			10 + 80 * (usage - target) / (100 - target) : /* ON  */  in led_activity_function()
143 			90 - 80 * (usage - target) / (100 - target);  /* OFF */  in led_activity_function()
146 	if (!activity_data->time_left || delay <= activity_data->time_left)  in led_activity_function()
147 		activity_data->time_left = delay;  in led_activity_function()
149 	delay = min_t(int, activity_data->time_left, 100);  in led_activity_function()
150 	mod_timer(&activity_data->timer, jiffies + msecs_to_jiffies(delay));  in led_activity_function()
158 	return sprintf(buf, "%u\n", activity_data->invert);  in led_invert_show()
173 	activity_data->invert = !!state;  in led_invert_store()
192 		return -ENOMEM;  in activity_activate()
196 	activity_data->led_cdev = led_cdev;  in activity_activate()
197 	timer_setup(&activity_data->timer, led_activity_function, 0);  in activity_activate()
198 	if (!led_cdev->blink_brightness)  in activity_activate()
199 		led_cdev->blink_brightness = led_cdev->max_brightness;  in activity_activate()
200 	led_activity_function(&activity_data->timer);  in activity_activate()
201 	set_bit(LED_BLINK_SW, &led_cdev->work_flags);  in activity_activate()
210 	del_timer_sync(&activity_data->timer);  in activity_deactivate()
212 	clear_bit(LED_BLINK_SW, &led_cdev->work_flags);  in activity_deactivate()
268 MODULE_DESCRIPTION("Activity LED trigger");