diff options
author | Wim Van Sebroeck <wim@iguana.be> | 2011-07-22 14:55:18 -0400 |
---|---|---|
committer | Wim Van Sebroeck <wim@iguana.be> | 2011-07-28 04:01:04 -0400 |
commit | 43316044d4f64da008d6aca7d4b60771b9a24eb8 (patch) | |
tree | 66d0d023a8713119d973e3c367efa21fb5a1908f | |
parent | 5efc7a6222f6408d29d6beb1142a302f31dc9eac (diff) |
watchdog: WatchDog Timer Driver Core - Add basic framework
The WatchDog Timer Driver Core is a framework
that contains the common code for all watchdog-driver's.
It also introduces a watchdog device structure and the
operations that go with it.
This is the introduction of this framework. This part
supports the minimal watchdog userspace API (or with
other words: the functionality to use /dev/watchdog's
open, release and write functionality as defined in
the simplest watchdog API). Extra functionality will
follow in the next set of patches.
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
-rw-r--r-- | Documentation/watchdog/00-INDEX | 2 | ||||
-rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 119 | ||||
-rw-r--r-- | drivers/watchdog/Kconfig | 11 | ||||
-rw-r--r-- | drivers/watchdog/Makefile | 4 | ||||
-rw-r--r-- | drivers/watchdog/watchdog_core.c | 101 | ||||
-rw-r--r-- | drivers/watchdog/watchdog_dev.c | 235 | ||||
-rw-r--r-- | drivers/watchdog/watchdog_dev.h | 33 | ||||
-rw-r--r-- | include/linux/watchdog.h | 61 |
8 files changed, 566 insertions, 0 deletions
diff --git a/Documentation/watchdog/00-INDEX b/Documentation/watchdog/00-INDEX index ee994513a9b1..fc51128071c2 100644 --- a/Documentation/watchdog/00-INDEX +++ b/Documentation/watchdog/00-INDEX | |||
@@ -8,6 +8,8 @@ src/ | |||
8 | - directory holding watchdog related example programs. | 8 | - directory holding watchdog related example programs. |
9 | watchdog-api.txt | 9 | watchdog-api.txt |
10 | - description of the Linux Watchdog driver API. | 10 | - description of the Linux Watchdog driver API. |
11 | watchdog-kernel-api.txt | ||
12 | - description of the Linux WatchDog Timer Driver Core kernel API. | ||
11 | watchdog-parameters.txt | 13 | watchdog-parameters.txt |
12 | - information on driver parameters (for drivers other than | 14 | - information on driver parameters (for drivers other than |
13 | the ones that have driver-specific files here) | 15 | the ones that have driver-specific files here) |
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt new file mode 100644 index 000000000000..3db67e74b80e --- /dev/null +++ b/Documentation/watchdog/watchdog-kernel-api.txt | |||
@@ -0,0 +1,119 @@ | |||
1 | The Linux WatchDog Timer Driver Core kernel API. | ||
2 | =============================================== | ||
3 | Last reviewed: 22-Jul-2011 | ||
4 | |||
5 | Wim Van Sebroeck <wim@iguana.be> | ||
6 | |||
7 | Introduction | ||
8 | ------------ | ||
9 | This document does not describe what a WatchDog Timer (WDT) Driver or Device is. | ||
10 | It also does not describe the API which can be used by user space to communicate | ||
11 | with a WatchDog Timer. If you want to know this then please read the following | ||
12 | file: Documentation/watchdog/watchdog-api.txt . | ||
13 | |||
14 | So what does this document describe? It describes the API that can be used by | ||
15 | WatchDog Timer Drivers that want to use the WatchDog Timer Driver Core | ||
16 | Framework. This framework provides all interfacing towards user space so that | ||
17 | the same code does not have to be reproduced each time. This also means that | ||
18 | a watchdog timer driver then only needs to provide the different routines | ||
19 | (operations) that control the watchdog timer (WDT). | ||
20 | |||
21 | The API | ||
22 | ------- | ||
23 | Each watchdog timer driver that wants to use the WatchDog Timer Driver Core | ||
24 | must #include <linux/watchdog.h> (you would have to do this anyway when | ||
25 | writing a watchdog device driver). This include file contains following | ||
26 | register/unregister routines: | ||
27 | |||
28 | extern int watchdog_register_device(struct watchdog_device *); | ||
29 | extern void watchdog_unregister_device(struct watchdog_device *); | ||
30 | |||
31 | The watchdog_register_device routine registers a watchdog timer device. | ||
32 | The parameter of this routine is a pointer to a watchdog_device structure. | ||
33 | This routine returns zero on success and a negative errno code for failure. | ||
34 | |||
35 | The watchdog_unregister_device routine deregisters a registered watchdog timer | ||
36 | device. The parameter of this routine is the pointer to the registered | ||
37 | watchdog_device structure. | ||
38 | |||
39 | The watchdog device structure looks like this: | ||
40 | |||
41 | struct watchdog_device { | ||
42 | const struct watchdog_info *info; | ||
43 | const struct watchdog_ops *ops; | ||
44 | void *driver_data; | ||
45 | unsigned long status; | ||
46 | }; | ||
47 | |||
48 | It contains following fields: | ||
49 | * info: a pointer to a watchdog_info structure. This structure gives some | ||
50 | additional information about the watchdog timer itself. (Like it's unique name) | ||
51 | * ops: a pointer to the list of watchdog operations that the watchdog supports. | ||
52 | * driver_data: a pointer to the drivers private data of a watchdog device. | ||
53 | This data should only be accessed via the watchdog_set_drvadata and | ||
54 | watchdog_get_drvdata routines. | ||
55 | * status: this field contains a number of status bits that give extra | ||
56 | information about the status of the device (Like: is the device opened via | ||
57 | the /dev/watchdog interface or not, ...). | ||
58 | |||
59 | The list of watchdog operations is defined as: | ||
60 | |||
61 | struct watchdog_ops { | ||
62 | struct module *owner; | ||
63 | /* mandatory operations */ | ||
64 | int (*start)(struct watchdog_device *); | ||
65 | int (*stop)(struct watchdog_device *); | ||
66 | /* optional operations */ | ||
67 | int (*ping)(struct watchdog_device *); | ||
68 | }; | ||
69 | |||
70 | It is important that you first define the module owner of the watchdog timer | ||
71 | driver's operations. This module owner will be used to lock the module when | ||
72 | the watchdog is active. (This to avoid a system crash when you unload the | ||
73 | module and /dev/watchdog is still open). | ||
74 | Some operations are mandatory and some are optional. The mandatory operations | ||
75 | are: | ||
76 | * start: this is a pointer to the routine that starts the watchdog timer | ||
77 | device. | ||
78 | The routine needs a pointer to the watchdog timer device structure as a | ||
79 | parameter. It returns zero on success or a negative errno code for failure. | ||
80 | * stop: with this routine the watchdog timer device is being stopped. | ||
81 | The routine needs a pointer to the watchdog timer device structure as a | ||
82 | parameter. It returns zero on success or a negative errno code for failure. | ||
83 | Some watchdog timer hardware can only be started and not be stopped. The | ||
84 | driver supporting this hardware needs to make sure that a start and stop | ||
85 | routine is being provided. This can be done by using a timer in the driver | ||
86 | that regularly sends a keepalive ping to the watchdog timer hardware. | ||
87 | |||
88 | Not all watchdog timer hardware supports the same functionality. That's why | ||
89 | all other routines/operations are optional. They only need to be provided if | ||
90 | they are supported. These optional routines/operations are: | ||
91 | * ping: this is the routine that sends a keepalive ping to the watchdog timer | ||
92 | hardware. | ||
93 | The routine needs a pointer to the watchdog timer device structure as a | ||
94 | parameter. It returns zero on success or a negative errno code for failure. | ||
95 | Most hardware that does not support this as a separate function uses the | ||
96 | start function to restart the watchdog timer hardware. And that's also what | ||
97 | the watchdog timer driver core does: to send a keepalive ping to the watchdog | ||
98 | timer hardware it will either use the ping operation (when available) or the | ||
99 | start operation (when the ping operation is not available). | ||
100 | |||
101 | The status bits should (preferably) be set with the set_bit and clear_bit alike | ||
102 | bit-operations. The status bits that are defined are: | ||
103 | * WDOG_DEV_OPEN: this status bit shows whether or not the watchdog device | ||
104 | was opened via /dev/watchdog. | ||
105 | (This bit should only be used by the WatchDog Timer Driver Core). | ||
106 | |||
107 | To get or set driver specific data the following two helper functions should be | ||
108 | used: | ||
109 | |||
110 | static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data) | ||
111 | static inline void *watchdog_get_drvdata(struct watchdog_device *wdd) | ||
112 | |||
113 | The watchdog_set_drvdata function allows you to add driver specific data. The | ||
114 | arguments of this function are the watchdog device where you want to add the | ||
115 | driver specific data to and a pointer to the data itself. | ||
116 | |||
117 | The watchdog_get_drvdata function allows you to retrieve driver specific data. | ||
118 | The argument of this function is the watchdog device where you want to retrieve | ||
119 | data from. The function retruns the pointer to the driver specific data. | ||
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index 0635e72e0794..f441726ddf2b 100644 --- a/drivers/watchdog/Kconfig +++ b/drivers/watchdog/Kconfig | |||
@@ -28,6 +28,17 @@ menuconfig WATCHDOG | |||
28 | 28 | ||
29 | if WATCHDOG | 29 | if WATCHDOG |
30 | 30 | ||
31 | config WATCHDOG_CORE | ||
32 | bool "WatchDog Timer Driver Core" | ||
33 | ---help--- | ||
34 | Say Y here if you want to use the new watchdog timer driver core. | ||
35 | This driver provides a framework for all watchdog timer drivers | ||
36 | and gives them the /dev/watchdog interface (and later also the | ||
37 | sysfs interface). | ||
38 | |||
39 | To compile this driver as a module, choose M here: the module will | ||
40 | be called watchdog. | ||
41 | |||
31 | config WATCHDOG_NOWAYOUT | 42 | config WATCHDOG_NOWAYOUT |
32 | bool "Disable watchdog shutdown on close" | 43 | bool "Disable watchdog shutdown on close" |
33 | help | 44 | help |
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index 9eaa212398d7..55bd5740e910 100644 --- a/drivers/watchdog/Makefile +++ b/drivers/watchdog/Makefile | |||
@@ -2,6 +2,10 @@ | |||
2 | # Makefile for the WatchDog device drivers. | 2 | # Makefile for the WatchDog device drivers. |
3 | # | 3 | # |
4 | 4 | ||
5 | # The WatchDog Timer Driver Core. | ||
6 | watchdog-objs += watchdog_core.o watchdog_dev.o | ||
7 | obj-$(CONFIG_WATCHDOG_CORE) += watchdog.o | ||
8 | |||
5 | # Only one watchdog can succeed. We probe the ISA/PCI/USB based | 9 | # Only one watchdog can succeed. We probe the ISA/PCI/USB based |
6 | # watchdog-cards first, then the architecture specific watchdog | 10 | # watchdog-cards first, then the architecture specific watchdog |
7 | # drivers and then the architecture independent "softdog" driver. | 11 | # drivers and then the architecture independent "softdog" driver. |
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c new file mode 100644 index 000000000000..47fc1267ad4e --- /dev/null +++ b/drivers/watchdog/watchdog_core.c | |||
@@ -0,0 +1,101 @@ | |||
1 | /* | ||
2 | * watchdog_core.c | ||
3 | * | ||
4 | * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>, | ||
5 | * All Rights Reserved. | ||
6 | * | ||
7 | * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>. | ||
8 | * | ||
9 | * This source code is part of the generic code that can be used | ||
10 | * by all the watchdog timer drivers. | ||
11 | * | ||
12 | * Based on source code of the following authors: | ||
13 | * Matt Domsch <Matt_Domsch@dell.com>, | ||
14 | * Rob Radez <rob@osinvestor.com>, | ||
15 | * Rusty Lynch <rusty@linux.co.intel.com> | ||
16 | * Satyam Sharma <satyam@infradead.org> | ||
17 | * Randy Dunlap <randy.dunlap@oracle.com> | ||
18 | * | ||
19 | * This program is free software; you can redistribute it and/or | ||
20 | * modify it under the terms of the GNU General Public License | ||
21 | * as published by the Free Software Foundation; either version | ||
22 | * 2 of the License, or (at your option) any later version. | ||
23 | * | ||
24 | * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw. | ||
25 | * admit liability nor provide warranty for any of this software. | ||
26 | * This material is provided "AS-IS" and at no charge. | ||
27 | */ | ||
28 | |||
29 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | ||
30 | |||
31 | #include <linux/module.h> /* For EXPORT_SYMBOL/module stuff/... */ | ||
32 | #include <linux/types.h> /* For standard types */ | ||
33 | #include <linux/errno.h> /* For the -ENODEV/... values */ | ||
34 | #include <linux/kernel.h> /* For printk/panic/... */ | ||
35 | #include <linux/watchdog.h> /* For watchdog specific items */ | ||
36 | #include <linux/init.h> /* For __init/__exit/... */ | ||
37 | |||
38 | #include "watchdog_dev.h" /* For watchdog_dev_register/... */ | ||
39 | |||
40 | /** | ||
41 | * watchdog_register_device() - register a watchdog device | ||
42 | * @wdd: watchdog device | ||
43 | * | ||
44 | * Register a watchdog device with the kernel so that the | ||
45 | * watchdog timer can be accessed from userspace. | ||
46 | * | ||
47 | * A zero is returned on success and a negative errno code for | ||
48 | * failure. | ||
49 | */ | ||
50 | int watchdog_register_device(struct watchdog_device *wdd) | ||
51 | { | ||
52 | int ret; | ||
53 | |||
54 | if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL) | ||
55 | return -EINVAL; | ||
56 | |||
57 | /* Mandatory operations need to be supported */ | ||
58 | if (wdd->ops->start == NULL || wdd->ops->stop == NULL) | ||
59 | return -EINVAL; | ||
60 | |||
61 | /* | ||
62 | * Note: now that all watchdog_device data has been verified, we | ||
63 | * will not check this anymore in other functions. If data gets | ||
64 | * corrupted in a later stage then we expect a kernel panic! | ||
65 | */ | ||
66 | |||
67 | /* We only support 1 watchdog device via the /dev/watchdog interface */ | ||
68 | ret = watchdog_dev_register(wdd); | ||
69 | if (ret) { | ||
70 | pr_err("error registering /dev/watchdog (err=%d).\n", ret); | ||
71 | return ret; | ||
72 | } | ||
73 | |||
74 | return 0; | ||
75 | } | ||
76 | EXPORT_SYMBOL_GPL(watchdog_register_device); | ||
77 | |||
78 | /** | ||
79 | * watchdog_unregister_device() - unregister a watchdog device | ||
80 | * @wdd: watchdog device to unregister | ||
81 | * | ||
82 | * Unregister a watchdog device that was previously successfully | ||
83 | * registered with watchdog_register_device(). | ||
84 | */ | ||
85 | void watchdog_unregister_device(struct watchdog_device *wdd) | ||
86 | { | ||
87 | int ret; | ||
88 | |||
89 | if (wdd == NULL) | ||
90 | return; | ||
91 | |||
92 | ret = watchdog_dev_unregister(wdd); | ||
93 | if (ret) | ||
94 | pr_err("error unregistering /dev/watchdog (err=%d).\n", ret); | ||
95 | } | ||
96 | EXPORT_SYMBOL_GPL(watchdog_unregister_device); | ||
97 | |||
98 | MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>"); | ||
99 | MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>"); | ||
100 | MODULE_DESCRIPTION("WatchDog Timer Driver Core"); | ||
101 | MODULE_LICENSE("GPL"); | ||
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c new file mode 100644 index 000000000000..366f49ce69b8 --- /dev/null +++ b/drivers/watchdog/watchdog_dev.c | |||
@@ -0,0 +1,235 @@ | |||
1 | /* | ||
2 | * watchdog_dev.c | ||
3 | * | ||
4 | * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>, | ||
5 | * All Rights Reserved. | ||
6 | * | ||
7 | * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>. | ||
8 | * | ||
9 | * | ||
10 | * This source code is part of the generic code that can be used | ||
11 | * by all the watchdog timer drivers. | ||
12 | * | ||
13 | * This part of the generic code takes care of the following | ||
14 | * misc device: /dev/watchdog. | ||
15 | * | ||
16 | * Based on source code of the following authors: | ||
17 | * Matt Domsch <Matt_Domsch@dell.com>, | ||
18 | * Rob Radez <rob@osinvestor.com>, | ||
19 | * Rusty Lynch <rusty@linux.co.intel.com> | ||
20 | * Satyam Sharma <satyam@infradead.org> | ||
21 | * Randy Dunlap <randy.dunlap@oracle.com> | ||
22 | * | ||
23 | * This program is free software; you can redistribute it and/or | ||
24 | * modify it under the terms of the GNU General Public License | ||
25 | * as published by the Free Software Foundation; either version | ||
26 | * 2 of the License, or (at your option) any later version. | ||
27 | * | ||
28 | * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw. | ||
29 | * admit liability nor provide warranty for any of this software. | ||
30 | * This material is provided "AS-IS" and at no charge. | ||
31 | */ | ||
32 | |||
33 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | ||
34 | |||
35 | #include <linux/module.h> /* For module stuff/... */ | ||
36 | #include <linux/types.h> /* For standard types (like size_t) */ | ||
37 | #include <linux/errno.h> /* For the -ENODEV/... values */ | ||
38 | #include <linux/kernel.h> /* For printk/panic/... */ | ||
39 | #include <linux/fs.h> /* For file operations */ | ||
40 | #include <linux/watchdog.h> /* For watchdog specific items */ | ||
41 | #include <linux/miscdevice.h> /* For handling misc devices */ | ||
42 | #include <linux/init.h> /* For __init/__exit/... */ | ||
43 | #include <linux/uaccess.h> /* For copy_to_user/put_user/... */ | ||
44 | |||
45 | /* make sure we only register one /dev/watchdog device */ | ||
46 | static unsigned long watchdog_dev_busy; | ||
47 | /* the watchdog device behind /dev/watchdog */ | ||
48 | static struct watchdog_device *wdd; | ||
49 | |||
50 | /* | ||
51 | * watchdog_ping: ping the watchdog. | ||
52 | * @wddev: the watchdog device to ping | ||
53 | * | ||
54 | * If the watchdog has no own ping operation then it needs to be | ||
55 | * restarted via the start operation. This wrapper function does | ||
56 | * exactly that. | ||
57 | */ | ||
58 | |||
59 | static int watchdog_ping(struct watchdog_device *wddev) | ||
60 | { | ||
61 | if (wddev->ops->ping) | ||
62 | return wddev->ops->ping(wddev); /* ping the watchdog */ | ||
63 | else | ||
64 | return wddev->ops->start(wddev); /* restart the watchdog */ | ||
65 | } | ||
66 | |||
67 | /* | ||
68 | * watchdog_write: writes to the watchdog. | ||
69 | * @file: file from VFS | ||
70 | * @data: user address of data | ||
71 | * @len: length of data | ||
72 | * @ppos: pointer to the file offset | ||
73 | * | ||
74 | * A write to a watchdog device is defined as a keepalive ping. | ||
75 | */ | ||
76 | |||
77 | static ssize_t watchdog_write(struct file *file, const char __user *data, | ||
78 | size_t len, loff_t *ppos) | ||
79 | { | ||
80 | size_t i; | ||
81 | char c; | ||
82 | |||
83 | if (len == 0) | ||
84 | return 0; | ||
85 | |||
86 | for (i = 0; i != len; i++) { | ||
87 | if (get_user(c, data + i)) | ||
88 | return -EFAULT; | ||
89 | } | ||
90 | |||
91 | /* someone wrote to us, so we send the watchdog a keepalive ping */ | ||
92 | watchdog_ping(wdd); | ||
93 | |||
94 | return len; | ||
95 | } | ||
96 | |||
97 | /* | ||
98 | * watchdog_open: open the /dev/watchdog device. | ||
99 | * @inode: inode of device | ||
100 | * @file: file handle to device | ||
101 | * | ||
102 | * When the /dev/watchdog device gets opened, we start the watchdog. | ||
103 | * Watch out: the /dev/watchdog device is single open, so we make sure | ||
104 | * it can only be opened once. | ||
105 | */ | ||
106 | |||
107 | static int watchdog_open(struct inode *inode, struct file *file) | ||
108 | { | ||
109 | int err = -EBUSY; | ||
110 | |||
111 | /* the watchdog is single open! */ | ||
112 | if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status)) | ||
113 | return -EBUSY; | ||
114 | |||
115 | /* | ||
116 | * If the /dev/watchdog device is open, we don't want the module | ||
117 | * to be unloaded. | ||
118 | */ | ||
119 | if (!try_module_get(wdd->ops->owner)) | ||
120 | goto out; | ||
121 | |||
122 | err = wdd->ops->start(wdd); | ||
123 | if (err < 0) | ||
124 | goto out_mod; | ||
125 | |||
126 | /* dev/watchdog is a virtual (and thus non-seekable) filesystem */ | ||
127 | return nonseekable_open(inode, file); | ||
128 | |||
129 | out_mod: | ||
130 | module_put(wdd->ops->owner); | ||
131 | out: | ||
132 | clear_bit(WDOG_DEV_OPEN, &wdd->status); | ||
133 | return err; | ||
134 | } | ||
135 | |||
136 | /* | ||
137 | * watchdog_release: release the /dev/watchdog device. | ||
138 | * @inode: inode of device | ||
139 | * @file: file handle to device | ||
140 | * | ||
141 | * This is the code for when /dev/watchdog gets closed. | ||
142 | */ | ||
143 | |||
144 | static int watchdog_release(struct inode *inode, struct file *file) | ||
145 | { | ||
146 | int err; | ||
147 | |||
148 | err = wdd->ops->stop(wdd); | ||
149 | if (err != 0) { | ||
150 | pr_crit("%s: watchdog did not stop!\n", wdd->info->identity); | ||
151 | watchdog_ping(wdd); | ||
152 | } | ||
153 | |||
154 | /* Allow the owner module to be unloaded again */ | ||
155 | module_put(wdd->ops->owner); | ||
156 | |||
157 | /* make sure that /dev/watchdog can be re-opened */ | ||
158 | clear_bit(WDOG_DEV_OPEN, &wdd->status); | ||
159 | |||
160 | return 0; | ||
161 | } | ||
162 | |||
163 | static const struct file_operations watchdog_fops = { | ||
164 | .owner = THIS_MODULE, | ||
165 | .write = watchdog_write, | ||
166 | .open = watchdog_open, | ||
167 | .release = watchdog_release, | ||
168 | }; | ||
169 | |||
170 | static struct miscdevice watchdog_miscdev = { | ||
171 | .minor = WATCHDOG_MINOR, | ||
172 | .name = "watchdog", | ||
173 | .fops = &watchdog_fops, | ||
174 | }; | ||
175 | |||
176 | /* | ||
177 | * watchdog_dev_register: | ||
178 | * @watchdog: watchdog device | ||
179 | * | ||
180 | * Register a watchdog device as /dev/watchdog. /dev/watchdog | ||
181 | * is actually a miscdevice and thus we set it up like that. | ||
182 | */ | ||
183 | |||
184 | int watchdog_dev_register(struct watchdog_device *watchdog) | ||
185 | { | ||
186 | int err; | ||
187 | |||
188 | /* Only one device can register for /dev/watchdog */ | ||
189 | if (test_and_set_bit(0, &watchdog_dev_busy)) { | ||
190 | pr_err("only one watchdog can use /dev/watchdog.\n"); | ||
191 | return -EBUSY; | ||
192 | } | ||
193 | |||
194 | wdd = watchdog; | ||
195 | |||
196 | err = misc_register(&watchdog_miscdev); | ||
197 | if (err != 0) { | ||
198 | pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n", | ||
199 | watchdog->info->identity, WATCHDOG_MINOR, err); | ||
200 | goto out; | ||
201 | } | ||
202 | |||
203 | return 0; | ||
204 | |||
205 | out: | ||
206 | wdd = NULL; | ||
207 | clear_bit(0, &watchdog_dev_busy); | ||
208 | return err; | ||
209 | } | ||
210 | |||
211 | /* | ||
212 | * watchdog_dev_unregister: | ||
213 | * @watchdog: watchdog device | ||
214 | * | ||
215 | * Deregister the /dev/watchdog device. | ||
216 | */ | ||
217 | |||
218 | int watchdog_dev_unregister(struct watchdog_device *watchdog) | ||
219 | { | ||
220 | /* Check that a watchdog device was registered in the past */ | ||
221 | if (!test_bit(0, &watchdog_dev_busy) || !wdd) | ||
222 | return -ENODEV; | ||
223 | |||
224 | /* We can only unregister the watchdog device that was registered */ | ||
225 | if (watchdog != wdd) { | ||
226 | pr_err("%s: watchdog was not registered as /dev/watchdog.\n", | ||
227 | watchdog->info->identity); | ||
228 | return -ENODEV; | ||
229 | } | ||
230 | |||
231 | misc_deregister(&watchdog_miscdev); | ||
232 | wdd = NULL; | ||
233 | clear_bit(0, &watchdog_dev_busy); | ||
234 | return 0; | ||
235 | } | ||
diff --git a/drivers/watchdog/watchdog_dev.h b/drivers/watchdog/watchdog_dev.h new file mode 100644 index 000000000000..bc7612be25ce --- /dev/null +++ b/drivers/watchdog/watchdog_dev.h | |||
@@ -0,0 +1,33 @@ | |||
1 | /* | ||
2 | * watchdog_core.h | ||
3 | * | ||
4 | * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>, | ||
5 | * All Rights Reserved. | ||
6 | * | ||
7 | * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>. | ||
8 | * | ||
9 | * This source code is part of the generic code that can be used | ||
10 | * by all the watchdog timer drivers. | ||
11 | * | ||
12 | * Based on source code of the following authors: | ||
13 | * Matt Domsch <Matt_Domsch@dell.com>, | ||
14 | * Rob Radez <rob@osinvestor.com>, | ||
15 | * Rusty Lynch <rusty@linux.co.intel.com> | ||
16 | * Satyam Sharma <satyam@infradead.org> | ||
17 | * Randy Dunlap <randy.dunlap@oracle.com> | ||
18 | * | ||
19 | * This program is free software; you can redistribute it and/or | ||
20 | * modify it under the terms of the GNU General Public License | ||
21 | * as published by the Free Software Foundation; either version | ||
22 | * 2 of the License, or (at your option) any later version. | ||
23 | * | ||
24 | * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw. | ||
25 | * admit liability nor provide warranty for any of this software. | ||
26 | * This material is provided "AS-IS" and at no charge. | ||
27 | */ | ||
28 | |||
29 | /* | ||
30 | * Functions/procedures to be called by the core | ||
31 | */ | ||
32 | int watchdog_dev_register(struct watchdog_device *); | ||
33 | int watchdog_dev_unregister(struct watchdog_device *); | ||
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h index 011bcfeb9f09..5ab31bfd2906 100644 --- a/include/linux/watchdog.h +++ b/include/linux/watchdog.h | |||
@@ -59,6 +59,67 @@ struct watchdog_info { | |||
59 | #define WATCHDOG_NOWAYOUT 0 | 59 | #define WATCHDOG_NOWAYOUT 0 |
60 | #endif | 60 | #endif |
61 | 61 | ||
62 | struct watchdog_ops; | ||
63 | struct watchdog_device; | ||
64 | |||
65 | /** struct watchdog_ops - The watchdog-devices operations | ||
66 | * | ||
67 | * @owner: The module owner. | ||
68 | * @start: The routine for starting the watchdog device. | ||
69 | * @stop: The routine for stopping the watchdog device. | ||
70 | * @ping: The routine that sends a keepalive ping to the watchdog device. | ||
71 | * | ||
72 | * The watchdog_ops structure contains a list of low-level operations | ||
73 | * that control a watchdog device. It also contains the module that owns | ||
74 | * these operations. The start and stop function are mandatory, all other | ||
75 | * functions are optonal. | ||
76 | */ | ||
77 | struct watchdog_ops { | ||
78 | struct module *owner; | ||
79 | /* mandatory operations */ | ||
80 | int (*start)(struct watchdog_device *); | ||
81 | int (*stop)(struct watchdog_device *); | ||
82 | /* optional operations */ | ||
83 | int (*ping)(struct watchdog_device *); | ||
84 | }; | ||
85 | |||
86 | /** struct watchdog_device - The structure that defines a watchdog device | ||
87 | * | ||
88 | * @info: Pointer to a watchdog_info structure. | ||
89 | * @ops: Pointer to the list of watchdog operations. | ||
90 | * @driver-data:Pointer to the drivers private data. | ||
91 | * @status: Field that contains the devices internal status bits. | ||
92 | * | ||
93 | * The watchdog_device structure contains all information about a | ||
94 | * watchdog timer device. | ||
95 | * | ||
96 | * The driver-data field may not be accessed directly. It must be accessed | ||
97 | * via the watchdog_set_drvdata and watchdog_get_drvdata helpers. | ||
98 | */ | ||
99 | struct watchdog_device { | ||
100 | const struct watchdog_info *info; | ||
101 | const struct watchdog_ops *ops; | ||
102 | void *driver_data; | ||
103 | unsigned long status; | ||
104 | /* Bit numbers for status flags */ | ||
105 | #define WDOG_DEV_OPEN 1 /* Opened via /dev/watchdog ? */ | ||
106 | }; | ||
107 | |||
108 | /* Use the following functions to manipulate watchdog driver specific data */ | ||
109 | static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data) | ||
110 | { | ||
111 | wdd->driver_data = data; | ||
112 | } | ||
113 | |||
114 | static inline void *watchdog_get_drvdata(struct watchdog_device *wdd) | ||
115 | { | ||
116 | return wdd->driver_data; | ||
117 | } | ||
118 | |||
119 | /* drivers/watchdog/core/watchdog_core.c */ | ||
120 | extern int watchdog_register_device(struct watchdog_device *); | ||
121 | extern void watchdog_unregister_device(struct watchdog_device *); | ||
122 | |||
62 | #endif /* __KERNEL__ */ | 123 | #endif /* __KERNEL__ */ |
63 | 124 | ||
64 | #endif /* ifndef _LINUX_WATCHDOG_H */ | 125 | #endif /* ifndef _LINUX_WATCHDOG_H */ |