aboutsummaryrefslogtreecommitdiff
path: root/drivers/greybus/svc_watchdog.c
blob: b6b1682c19c455a87810e4c6477275430a8c25fa (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
// SPDX-License-Identifier: GPL-2.0
/*
 * SVC Greybus "watchdog" driver.
 *
 * Copyright 2016 Google Inc.
 */

#include <linux/delay.h>
#include <linux/suspend.h>
#include <linux/workqueue.h>
#include <linux/greybus.h>

#define SVC_WATCHDOG_PERIOD	(2 * HZ)

struct gb_svc_watchdog {
	struct delayed_work	work;
	struct gb_svc		*svc;
	bool			enabled;
	struct notifier_block pm_notifier;
};

static struct delayed_work reset_work;

static int svc_watchdog_pm_notifier(struct notifier_block *notifier,
				    unsigned long pm_event, void *unused)
{
	struct gb_svc_watchdog *watchdog =
		container_of(notifier, struct gb_svc_watchdog, pm_notifier);

	switch (pm_event) {
	case PM_SUSPEND_PREPARE:
		gb_svc_watchdog_disable(watchdog->svc);
		break;
	case PM_POST_SUSPEND:
		gb_svc_watchdog_enable(watchdog->svc);
		break;
	default:
		break;
	}

	return NOTIFY_DONE;
}

static void greybus_reset(struct work_struct *work)
{
	static char const start_path[] = "/system/bin/start";
	static char *envp[] = {
		"HOME=/",
		"PATH=/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin",
		NULL,
	};
	static char *argv[] = {
		(char *)start_path,
		"unipro_reset",
		NULL,
	};

	pr_err("svc_watchdog: calling \"%s %s\" to reset greybus network!\n",
	       argv[0], argv[1]);
	call_usermodehelper(start_path, argv, envp, UMH_WAIT_EXEC);
}

static void do_work(struct work_struct *work)
{
	struct gb_svc_watchdog *watchdog;
	struct gb_svc *svc;
	int retval;

	watchdog = container_of(work, struct gb_svc_watchdog, work.work);
	svc = watchdog->svc;

	dev_dbg(&svc->dev, "%s: ping.\n", __func__);
	retval = gb_svc_ping(svc);
	if (retval) {
		/*
		 * Something went really wrong, let's warn userspace and then
		 * pull the plug and reset the whole greybus network.
		 * We need to do this outside of this workqueue as we will be
		 * tearing down the svc device itself.  So queue up
		 * yet-another-callback to do that.
		 */
		dev_err(&svc->dev,
			"SVC ping has returned %d, something is wrong!!!\n",
			retval);

		if (svc->action == GB_SVC_WATCHDOG_BITE_PANIC_KERNEL) {
			panic("SVC is not responding\n");
		} else if (svc->action == GB_SVC_WATCHDOG_BITE_RESET_UNIPRO) {
			dev_err(&svc->dev, "Resetting the greybus network, watch out!!!\n");

			INIT_DELAYED_WORK(&reset_work, greybus_reset);
			schedule_delayed_work(&reset_work, HZ / 2);

			/*
			 * Disable ourselves, we don't want to trip again unless
			 * userspace wants us to.
			 */
			watchdog->enabled = false;
		}
	}

	/* resubmit our work to happen again, if we are still "alive" */
	if (watchdog->enabled)
		schedule_delayed_work(&watchdog->work, SVC_WATCHDOG_PERIOD);
}

int gb_svc_watchdog_create(struct gb_svc *svc)
{
	struct gb_svc_watchdog *watchdog;
	int retval;

	if (svc->watchdog)
		return 0;

	watchdog = kmalloc(sizeof(*watchdog), GFP_KERNEL);
	if (!watchdog)
		return -ENOMEM;

	watchdog->enabled = false;
	watchdog->svc = svc;
	INIT_DELAYED_WORK(&watchdog->work, do_work);
	svc->watchdog = watchdog;

	watchdog->pm_notifier.notifier_call = svc_watchdog_pm_notifier;
	retval = register_pm_notifier(&watchdog->pm_notifier);
	if (retval) {
		dev_err(&svc->dev, "error registering pm notifier(%d)\n",
			retval);
		goto svc_watchdog_create_err;
	}

	retval = gb_svc_watchdog_enable(svc);
	if (retval) {
		dev_err(&svc->dev, "error enabling watchdog (%d)\n", retval);
		unregister_pm_notifier(&watchdog->pm_notifier);
		goto svc_watchdog_create_err;
	}
	return retval;

svc_watchdog_create_err:
	svc->watchdog = NULL;
	kfree(watchdog);

	return retval;
}

void gb_svc_watchdog_destroy(struct gb_svc *svc)
{
	struct gb_svc_watchdog *watchdog = svc->watchdog;

	if (!watchdog)
		return;

	unregister_pm_notifier(&watchdog->pm_notifier);
	gb_svc_watchdog_disable(svc);
	svc->watchdog = NULL;
	kfree(watchdog);
}

bool gb_svc_watchdog_enabled(struct gb_svc *svc)
{
	if (!svc || !svc->watchdog)
		return false;
	return svc->watchdog->enabled;
}

int gb_svc_watchdog_enable(struct gb_svc *svc)
{
	struct gb_svc_watchdog *watchdog;

	if (!svc->watchdog)
		return -ENODEV;

	watchdog = svc->watchdog;
	if (watchdog->enabled)
		return 0;

	watchdog->enabled = true;
	schedule_delayed_work(&watchdog->work, SVC_WATCHDOG_PERIOD);
	return 0;
}

int gb_svc_watchdog_disable(struct gb_svc *svc)
{
	struct gb_svc_watchdog *watchdog;

	if (!svc->watchdog)
		return -ENODEV;

	watchdog = svc->watchdog;
	if (!watchdog->enabled)
		return 0;

	watchdog->enabled = false;
	cancel_delayed_work_sync(&watchdog->work);
	return 0;
}