summaryrefslogtreecommitdiffstats
path: root/drivers/power/reset/ltc2952-poweroff.c
blob: 34f38a3dc3ffbc8e2fec49e7d668d5456c283c59 (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
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
/*
 * LTC2952 (PowerPath) driver
 *
 * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>
 * Maintainer: René Moll <linux@r-moll.nl>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * ----------------------------------------
 * - 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.
 *
 * - 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/gpio/consumer.h>
#include <linux/reboot.h>

struct ltc2952_poweroff_data {
	struct hrtimer timer_trigger;
	struct hrtimer timer_wde;

	ktime_t trigger_delay;
	ktime_t wde_interval;

	struct device *dev;

	unsigned int virq;

	/**
	 * 0: trigger
	 * 1: watchdog
	 * 2: kill
	 */
	struct gpio_desc *gpio[3];
};

static int ltc2952_poweroff_panic;
static struct ltc2952_poweroff_data *ltc2952_data;

#define POWERPATH_IO_TRIGGER	0
#define POWERPATH_IO_WATCHDOG	1
#define POWERPATH_IO_KILL	2

/**
 * 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;

	if (ltc2952_poweroff_panic)
		return HRTIMER_NORESTART;

	state = gpiod_get_value(ltc2952_data->gpio[POWERPATH_IO_WATCHDOG]);
	gpiod_set_value(ltc2952_data->gpio[POWERPATH_IO_WATCHDOG], !state);

	now = hrtimer_cb_get_time(timer);
	overruns = hrtimer_forward(timer, now, ltc2952_data->wde_interval);

	return HRTIMER_RESTART;
}

static enum hrtimer_restart ltc2952_poweroff_timer_trigger(
	struct hrtimer *timer)
{
	int ret;

	ret = hrtimer_start(&ltc2952_data->timer_wde,
		ltc2952_data->wde_interval, HRTIMER_MODE_REL);

	if (ret) {
		dev_err(ltc2952_data->dev, "unable to start the timer\n");
		/*
		 * The device will not toggle the watchdog reset,
		 * thus shut down is only safe if the PowerPath controller
		 * has a long enough time-off before triggering a hardware
		 * power-off.
		 *
		 * Only sending a warning as the system will power-off anyway
		 */
	}

	dev_info(ltc2952_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)
{
	int ret;
	struct ltc2952_poweroff_data *data = dev_id;

	if (ltc2952_poweroff_panic)
		goto irq_ok;

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

	if (!hrtimer_active(&data->timer_trigger)) {
		ret = hrtimer_start(&data->timer_trigger, data->trigger_delay,
			HRTIMER_MODE_REL);

		if (ret)
			dev_err(data->dev, "unable to start the wait timer\n");
	} else {
		ret = hrtimer_cancel(&data->timer_trigger);
		/* omitting return value check, timer should have been valid */
	}

irq_ok:
	return IRQ_HANDLED;
}

static void ltc2952_poweroff_kill(void)
{
	gpiod_set_value(ltc2952_data->gpio[POWERPATH_IO_KILL], 1);
}

static int ltc2952_poweroff_suspend(struct platform_device *pdev,
	pm_message_t state)
{
	return -ENOSYS;
}

static int ltc2952_poweroff_resume(struct platform_device *pdev)
{
	return -ENOSYS;
}

static void ltc2952_poweroff_default(struct ltc2952_poweroff_data *data)
{
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(data->gpio); i++)
		data->gpio[i] = NULL;

	data->wde_interval = ktime_set(0, 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, virq;
	unsigned int i;
	struct ltc2952_poweroff_data *data;

	static char *name[] = {
		"trigger",
		"watchdog",
		"kill",
		NULL
	};

	data = ltc2952_data;
	ltc2952_poweroff_default(ltc2952_data);

	for (i = 0; i < ARRAY_SIZE(ltc2952_data->gpio); i++) {
		ltc2952_data->gpio[i] = gpiod_get(&pdev->dev, name[i]);

		if (IS_ERR(ltc2952_data->gpio[i])) {
			ret = PTR_ERR(ltc2952_data->gpio[i]);
			dev_err(&pdev->dev,
				"unable to claim the following gpio: %s\n",
				name[i]);
			goto err_io;
		}
	}

	ret = gpiod_direction_output(
		ltc2952_data->gpio[POWERPATH_IO_WATCHDOG], 0);
	if (ret) {
		dev_err(&pdev->dev, "unable to use watchdog-gpio as output\n");
		goto err_io;
	}

	ret = gpiod_direction_output(ltc2952_data->gpio[POWERPATH_IO_KILL], 0);
	if (ret) {
		dev_err(&pdev->dev, "unable to use kill-gpio as output\n");
		goto err_io;
	}

	virq = gpiod_to_irq(ltc2952_data->gpio[POWERPATH_IO_TRIGGER]);
	if (virq < 0) {
		dev_err(&pdev->dev, "cannot map GPIO as interrupt");
		goto err_io;
	}

	ltc2952_data->virq = virq;
	ret = request_irq(virq,
		ltc2952_poweroff_handler,
		(IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
		"ltc2952-poweroff",
		ltc2952_data
	);

	if (ret) {
		dev_err(&pdev->dev, "cannot configure an interrupt handler\n");
		goto err_io;
	}

	return 0;

err_io:
	for (i = 0; i < ARRAY_SIZE(ltc2952_data->gpio); i++)
		if (ltc2952_data->gpio[i])
			gpiod_put(ltc2952_data->gpio[i]);

	return ret;
}

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

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

	ltc2952_data = kzalloc(sizeof(*ltc2952_data), GFP_KERNEL);
	if (!ltc2952_data)
		return -ENOMEM;

	ltc2952_data->dev = &pdev->dev;

	ret = ltc2952_poweroff_init(pdev);
	if (ret)
		goto err;

	pm_power_off = &ltc2952_poweroff_kill;

	dev_info(&pdev->dev, "probe successful\n");

	return 0;

err:
	kfree(ltc2952_data);
	return ret;
}

static int ltc2952_poweroff_remove(struct platform_device *pdev)
{
	unsigned int i;

	pm_power_off = NULL;

	if (ltc2952_data) {
		free_irq(ltc2952_data->virq, ltc2952_data);

		for (i = 0; i < ARRAY_SIZE(ltc2952_data->gpio); i++)
			gpiod_put(ltc2952_data->gpio[i]);

		kfree(ltc2952_data);
	}

	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,
	},
	.suspend = ltc2952_poweroff_suspend,
	.resume = ltc2952_poweroff_resume,
};

static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
	unsigned long code, void *unused)
{
	ltc2952_poweroff_panic = 1;
	return NOTIFY_DONE;
}

static struct notifier_block ltc2952_poweroff_panic_nb = {
	.notifier_call = ltc2952_poweroff_notify_panic,
};

static int __init ltc2952_poweroff_platform_init(void)
{
	ltc2952_poweroff_panic = 0;

	atomic_notifier_chain_register(&panic_notifier_list,
		&ltc2952_poweroff_panic_nb);

	return platform_driver_register(&ltc2952_poweroff_driver);
}

static void __exit ltc2952_poweroff_platform_exit(void)
{
	atomic_notifier_chain_unregister(&panic_notifier_list,
		&ltc2952_poweroff_panic_nb);

	platform_driver_unregister(&ltc2952_poweroff_driver);
}

module_init(ltc2952_poweroff_platform_init);
module_exit(ltc2952_poweroff_platform_exit);

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