1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * SVC Greybus "watchdog" driver. |
4 | * |
5 | * Copyright 2016 Google Inc. |
6 | */ |
7 | |
8 | #include <linux/delay.h> |
9 | #include <linux/suspend.h> |
10 | #include <linux/workqueue.h> |
11 | #include <linux/greybus.h> |
12 | |
13 | #define SVC_WATCHDOG_PERIOD (2 * HZ) |
14 | |
15 | struct gb_svc_watchdog { |
16 | struct delayed_work work; |
17 | struct gb_svc *svc; |
18 | bool enabled; |
19 | struct notifier_block pm_notifier; |
20 | }; |
21 | |
22 | static struct delayed_work reset_work; |
23 | |
24 | static int svc_watchdog_pm_notifier(struct notifier_block *notifier, |
25 | unsigned long pm_event, void *unused) |
26 | { |
27 | struct gb_svc_watchdog *watchdog = |
28 | container_of(notifier, struct gb_svc_watchdog, pm_notifier); |
29 | |
30 | switch (pm_event) { |
31 | case PM_SUSPEND_PREPARE: |
32 | gb_svc_watchdog_disable(svc: watchdog->svc); |
33 | break; |
34 | case PM_POST_SUSPEND: |
35 | gb_svc_watchdog_enable(svc: watchdog->svc); |
36 | break; |
37 | default: |
38 | break; |
39 | } |
40 | |
41 | return NOTIFY_DONE; |
42 | } |
43 | |
44 | static void greybus_reset(struct work_struct *work) |
45 | { |
46 | static char const start_path[] = "/system/bin/start" ; |
47 | static char *envp[] = { |
48 | "HOME=/" , |
49 | "PATH=/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin" , |
50 | NULL, |
51 | }; |
52 | static char *argv[] = { |
53 | (char *)start_path, |
54 | "unipro_reset" , |
55 | NULL, |
56 | }; |
57 | |
58 | pr_err("svc_watchdog: calling \"%s %s\" to reset greybus network!\n" , |
59 | argv[0], argv[1]); |
60 | call_usermodehelper(path: start_path, argv, envp, UMH_WAIT_EXEC); |
61 | } |
62 | |
63 | static void do_work(struct work_struct *work) |
64 | { |
65 | struct gb_svc_watchdog *watchdog; |
66 | struct gb_svc *svc; |
67 | int retval; |
68 | |
69 | watchdog = container_of(work, struct gb_svc_watchdog, work.work); |
70 | svc = watchdog->svc; |
71 | |
72 | dev_dbg(&svc->dev, "%s: ping.\n" , __func__); |
73 | retval = gb_svc_ping(svc); |
74 | if (retval) { |
75 | /* |
76 | * Something went really wrong, let's warn userspace and then |
77 | * pull the plug and reset the whole greybus network. |
78 | * We need to do this outside of this workqueue as we will be |
79 | * tearing down the svc device itself. So queue up |
80 | * yet-another-callback to do that. |
81 | */ |
82 | dev_err(&svc->dev, |
83 | "SVC ping has returned %d, something is wrong!!!\n" , |
84 | retval); |
85 | |
86 | if (svc->action == GB_SVC_WATCHDOG_BITE_PANIC_KERNEL) { |
87 | panic(fmt: "SVC is not responding\n" ); |
88 | } else if (svc->action == GB_SVC_WATCHDOG_BITE_RESET_UNIPRO) { |
89 | dev_err(&svc->dev, "Resetting the greybus network, watch out!!!\n" ); |
90 | |
91 | INIT_DELAYED_WORK(&reset_work, greybus_reset); |
92 | schedule_delayed_work(dwork: &reset_work, HZ / 2); |
93 | |
94 | /* |
95 | * Disable ourselves, we don't want to trip again unless |
96 | * userspace wants us to. |
97 | */ |
98 | watchdog->enabled = false; |
99 | } |
100 | } |
101 | |
102 | /* resubmit our work to happen again, if we are still "alive" */ |
103 | if (watchdog->enabled) |
104 | schedule_delayed_work(dwork: &watchdog->work, SVC_WATCHDOG_PERIOD); |
105 | } |
106 | |
107 | int gb_svc_watchdog_create(struct gb_svc *svc) |
108 | { |
109 | struct gb_svc_watchdog *watchdog; |
110 | int retval; |
111 | |
112 | if (svc->watchdog) |
113 | return 0; |
114 | |
115 | watchdog = kmalloc(size: sizeof(*watchdog), GFP_KERNEL); |
116 | if (!watchdog) |
117 | return -ENOMEM; |
118 | |
119 | watchdog->enabled = false; |
120 | watchdog->svc = svc; |
121 | INIT_DELAYED_WORK(&watchdog->work, do_work); |
122 | svc->watchdog = watchdog; |
123 | |
124 | watchdog->pm_notifier.notifier_call = svc_watchdog_pm_notifier; |
125 | retval = register_pm_notifier(nb: &watchdog->pm_notifier); |
126 | if (retval) { |
127 | dev_err(&svc->dev, "error registering pm notifier(%d)\n" , |
128 | retval); |
129 | goto svc_watchdog_create_err; |
130 | } |
131 | |
132 | retval = gb_svc_watchdog_enable(svc); |
133 | if (retval) { |
134 | dev_err(&svc->dev, "error enabling watchdog (%d)\n" , retval); |
135 | unregister_pm_notifier(nb: &watchdog->pm_notifier); |
136 | goto svc_watchdog_create_err; |
137 | } |
138 | return retval; |
139 | |
140 | svc_watchdog_create_err: |
141 | svc->watchdog = NULL; |
142 | kfree(objp: watchdog); |
143 | |
144 | return retval; |
145 | } |
146 | |
147 | void gb_svc_watchdog_destroy(struct gb_svc *svc) |
148 | { |
149 | struct gb_svc_watchdog *watchdog = svc->watchdog; |
150 | |
151 | if (!watchdog) |
152 | return; |
153 | |
154 | unregister_pm_notifier(nb: &watchdog->pm_notifier); |
155 | gb_svc_watchdog_disable(svc); |
156 | svc->watchdog = NULL; |
157 | kfree(objp: watchdog); |
158 | } |
159 | |
160 | bool gb_svc_watchdog_enabled(struct gb_svc *svc) |
161 | { |
162 | if (!svc || !svc->watchdog) |
163 | return false; |
164 | return svc->watchdog->enabled; |
165 | } |
166 | |
167 | int gb_svc_watchdog_enable(struct gb_svc *svc) |
168 | { |
169 | struct gb_svc_watchdog *watchdog; |
170 | |
171 | if (!svc->watchdog) |
172 | return -ENODEV; |
173 | |
174 | watchdog = svc->watchdog; |
175 | if (watchdog->enabled) |
176 | return 0; |
177 | |
178 | watchdog->enabled = true; |
179 | schedule_delayed_work(dwork: &watchdog->work, SVC_WATCHDOG_PERIOD); |
180 | return 0; |
181 | } |
182 | |
183 | int gb_svc_watchdog_disable(struct gb_svc *svc) |
184 | { |
185 | struct gb_svc_watchdog *watchdog; |
186 | |
187 | if (!svc->watchdog) |
188 | return -ENODEV; |
189 | |
190 | watchdog = svc->watchdog; |
191 | if (!watchdog->enabled) |
192 | return 0; |
193 | |
194 | watchdog->enabled = false; |
195 | cancel_delayed_work_sync(dwork: &watchdog->work); |
196 | return 0; |
197 | } |
198 | |