summaryrefslogtreecommitdiff
path: root/drivers/power/reset/ltc2952-poweroff.c
blob: e4a0cc45b3d11a51813012da750b2f07ce79de08 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * LTC2952 (PowerPath) driver
 *
 * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>
 * Maintainer: René Moll <linux@r-moll.nl>
 *
 * ----------------------------------------
 * - Description
 * ----------------------------------------
 *
 * This driver is to be used with an external PowerPath Controller (LTC2952).
 * Its function is to determine when a external shut down is triggered
 * and react by properly shutting down the system.
 *
 * This driver expects a device tree with a ltc2952 entry for pin mapping.
 *
 * ----------------------------------------
 * - GPIO
 * ----------------------------------------
 *
 * The following GPIOs are used:
 * - trigger (input)
 *     A level change indicates the shut-down trigger. If it's state reverts
 *     within the time-out defined by trigger_delay, the shut down is not
 *     executed. If no pin is assigned to this input, the driver will start the
 *     watchdog toggle immediately. The chip will only power off the system if
 *     it is requested to do so through the kill line.
 *
 * - watchdog (output)
 *     Once a shut down is triggered, the driver will toggle this signal,
 *     with an internal (wde_interval) to stall the hardware shut down.
 *
 * - kill (output)
 *     The last action during shut down is triggering this signalling, such
 *     that the PowerPath Control will power down the hardware.
 *
 * ----------------------------------------
 * - Interrupts
 * ----------------------------------------
 *
 * The driver requires a non-shared, edge-triggered interrupt on the trigger
 * GPIO.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/ktime.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/gpio/consumer.h>
#include <linux/reboot.h>

struct ltc2952_poweroff {
	struct hrtimer timer_trigger;
	struct hrtimer timer_wde;

	ktime_t trigger_delay;
	ktime_t wde_interval;

	struct device *dev;

	struct gpio_desc *gpio_trigger;
	struct gpio_desc *gpio_watchdog;
	struct gpio_desc *gpio_kill;

	bool kernel_panic;
	struct notifier_block panic_notifier;
};

#define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)

/*
 * This global variable is only needed for pm_power_off. We should
 * remove it entirely once we don't need the global state anymore.
 */
static struct ltc2952_poweroff *ltc2952_data;

/**
 * ltc2952_poweroff_timer_wde - Timer callback
 * Toggles the watchdog reset signal each wde_interval
 *
 * @timer: corresponding timer
 *
 * Returns HRTIMER_RESTART for an infinite loop which will only stop when the
 * machine actually shuts down
 */
static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
{
	ktime_t now;
	int state;
	unsigned long overruns;
	struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);

	if (data->kernel_panic)
		return HRTIMER_NORESTART;

	state = gpiod_get_value(data->gpio_watchdog);
	gpiod_set_value(data->gpio_watchdog, !state);

	now = hrtimer_cb_get_time(timer);
	overruns = hrtimer_forward(timer, now, data->wde_interval);

	return HRTIMER_RESTART;
}

static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
{
	hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);
}

static enum hrtimer_restart
ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
{
	struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);

	ltc2952_poweroff_start_wde(data);
	dev_info(data->dev, "executing shutdown\n");
	orderly_poweroff(true);

	return HRTIMER_NORESTART;
}

/**
 * ltc2952_poweroff_handler - Interrupt handler
 * Triggered each time the trigger signal changes state and (de)activates a
 * time-out (timer_trigger). Once the time-out is actually reached the shut
 * down is executed.
 *
 * @irq: IRQ number
 * @dev_id: pointer to the main data structure
 */
static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)
{
	struct ltc2952_poweroff *data = dev_id;

	if (data->kernel_panic || hrtimer_active(&data->timer_wde)) {
		/* shutdown is already triggered, nothing to do any more */
		return IRQ_HANDLED;
	}

	if (gpiod_get_value(data->gpio_trigger)) {
		hrtimer_start(&data->timer_trigger, data->trigger_delay,
			      HRTIMER_MODE_REL);
	} else {
		hrtimer_cancel(&data->timer_trigger);
	}
	return IRQ_HANDLED;
}

static void ltc2952_poweroff_kill(void)
{
	gpiod_set_value(ltc2952_data->gpio_kill, 1);
}

static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
{
	data->wde_interval = 300L * 1E6L;
	data->trigger_delay = ktime_set(2, 500L*1E6L);

	hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	data->timer_trigger.function = ltc2952_poweroff_timer_trigger;

	hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	data->timer_wde.function = ltc2952_poweroff_timer_wde;
}

static int ltc2952_poweroff_init(struct platform_device *pdev)
{
	int ret;
	struct ltc2952_poweroff *data = platform_get_drvdata(pdev);

	ltc2952_poweroff_default(data);

	data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
					     GPIOD_OUT_LOW);
	if (IS_ERR(data->gpio_watchdog)) {
		ret = PTR_ERR(data->gpio_watchdog);
		dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");
		return ret;
	}

	data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);
	if (IS_ERR(data->gpio_kill)) {
		ret = PTR_ERR(data->gpio_kill);
		dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");
		return ret;
	}

	data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger",
						     GPIOD_IN);
	if (IS_ERR(data->gpio_trigger)) {
		/*
		 * It's not a problem if the trigger gpio isn't available, but
		 * it is worth a warning if its use was defined in the device
		 * tree.
		 */
		dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");
		data->gpio_trigger = NULL;
	}

	if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
			     ltc2952_poweroff_handler,
			     (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
			     "ltc2952-poweroff",
			     data)) {
		/*
		 * Some things may have happened:
		 * - No trigger input was defined
		 * - Claiming the GPIO failed
		 * - We could not map to an IRQ
		 * - We couldn't register an interrupt handler
		 *
		 * None of these really are problems, but all of them
		 * disqualify the push button from controlling the power.
		 *
		 * It is therefore important to note that if the ltc2952
		 * detects a button press for long enough, it will still start
		 * its own powerdown window and cut the power on us if we don't
		 * start the watchdog trigger.
		 */
		if (data->gpio_trigger) {
			dev_warn(&pdev->dev,
				 "unable to configure the trigger interrupt\n");
			devm_gpiod_put(&pdev->dev, data->gpio_trigger);
			data->gpio_trigger = NULL;
		}
		dev_info(&pdev->dev,
			 "power down trigger input will not be used\n");
		ltc2952_poweroff_start_wde(data);
	}

	return 0;
}

static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
					 unsigned long code, void *unused)
{
	struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);

	data->kernel_panic = true;
	return NOTIFY_DONE;
}

static int ltc2952_poweroff_probe(struct platform_device *pdev)
{
	int ret;
	struct ltc2952_poweroff *data;

	if (pm_power_off) {
		dev_err(&pdev->dev, "pm_power_off already registered");
		return -EBUSY;
	}

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

	data->dev = &pdev->dev;
	platform_set_drvdata(pdev, data);

	ret = ltc2952_poweroff_init(pdev);
	if (ret)
		return ret;

	/* TODO: remove ltc2952_data */
	ltc2952_data = data;
	pm_power_off = ltc2952_poweroff_kill;

	data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;
	atomic_notifier_chain_register(&panic_notifier_list,
				       &data->panic_notifier);
	dev_info(&pdev->dev, "probe successful\n");

	return 0;
}

static int ltc2952_poweroff_remove(struct platform_device *pdev)
{
	struct ltc2952_poweroff *data = platform_get_drvdata(pdev);

	pm_power_off = NULL;
	hrtimer_cancel(&data->timer_trigger);
	hrtimer_cancel(&data->timer_wde);
	atomic_notifier_chain_unregister(&panic_notifier_list,
					 &data->panic_notifier);
	return 0;
}

static const struct of_device_id of_ltc2952_poweroff_match[] = {
	{ .compatible = "lltc,ltc2952"},
	{},
};
MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);

static struct platform_driver ltc2952_poweroff_driver = {
	.probe = ltc2952_poweroff_probe,
	.remove = ltc2952_poweroff_remove,
	.driver = {
		.name = "ltc2952-poweroff",
		.of_match_table = of_ltc2952_poweroff_match,
	},
};

module_platform_driver(ltc2952_poweroff_driver);

MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
MODULE_DESCRIPTION("LTC PowerPath power-off driver");
MODULE_LICENSE("GPL v2");