diff options
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 10 | ||||
| -rw-r--r-- | drivers/watchdog/watchdog_core.c | 43 | ||||
| -rw-r--r-- | drivers/watchdog/watchdog_core.h | 4 | ||||
| -rw-r--r-- | drivers/watchdog/watchdog_dev.c | 127 | ||||
| -rw-r--r-- | include/linux/watchdog.h | 6 |
5 files changed, 140 insertions, 50 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index 25fe4304f2f..3c85fc7dc1f 100644 --- a/Documentation/watchdog/watchdog-kernel-api.txt +++ b/Documentation/watchdog/watchdog-kernel-api.txt @@ -1,6 +1,6 @@ The Linux WatchDog Timer Driver Core kernel API. =============================================== -Last reviewed: 16-Mar-2012 +Last reviewed: 21-May-2012 Wim Van Sebroeck <wim@iguana.be> @@ -39,6 +39,8 @@ watchdog_device structure. The watchdog device structure looks like this: struct watchdog_device { + int id; + struct cdev cdev; const struct watchdog_info *info; const struct watchdog_ops *ops; unsigned int bootstatus; @@ -50,6 +52,12 @@ struct watchdog_device { }; It contains following fields: +* id: set by watchdog_register_device, id 0 is special. It has both a + /dev/watchdog0 cdev (dynamic major, minor 0) as well as the old + /dev/watchdog miscdev. The id is set automatically when calling + watchdog_register_device. +* cdev: cdev for the dynamic /dev/watchdog<id> device nodes. This + field is also populated by watchdog_register_device. * info: a pointer to a watchdog_info structure. This structure gives some additional information about the watchdog timer itself. (Like it's unique name) * ops: a pointer to the list of watchdog operations that the watchdog supports. diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c index 8598308278d..5f987936900 100644 --- a/drivers/watchdog/watchdog_core.c +++ b/drivers/watchdog/watchdog_core.c @@ -34,9 +34,12 @@ #include <linux/kernel.h> /* For printk/panic/... */ #include <linux/watchdog.h> /* For watchdog specific items */ #include <linux/init.h> /* For __init/__exit/... */ +#include <linux/idr.h> /* For ida_* macros */ #include "watchdog_core.h" /* For watchdog_dev_register/... */ +static DEFINE_IDA(watchdog_ida); + /** * watchdog_register_device() - register a watchdog device * @wdd: watchdog device @@ -49,7 +52,7 @@ */ int watchdog_register_device(struct watchdog_device *wdd) { - int ret; + int ret, id; if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL) return -EINVAL; @@ -74,11 +77,28 @@ int watchdog_register_device(struct watchdog_device *wdd) * corrupted in a later stage then we expect a kernel panic! */ - /* We only support 1 watchdog device via the /dev/watchdog interface */ + id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL); + if (id < 0) + return id; + wdd->id = id; + ret = watchdog_dev_register(wdd); if (ret) { - pr_err("error registering /dev/watchdog (err=%d)\n", ret); - return ret; + ida_simple_remove(&watchdog_ida, id); + if (!(id == 0 && ret == -EBUSY)) + return ret; + + /* Retry in case a legacy watchdog module exists */ + id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL); + if (id < 0) + return id; + wdd->id = id; + + ret = watchdog_dev_register(wdd); + if (ret) { + ida_simple_remove(&watchdog_ida, id); + return ret; + } } return 0; @@ -102,9 +122,24 @@ void watchdog_unregister_device(struct watchdog_device *wdd) ret = watchdog_dev_unregister(wdd); if (ret) pr_err("error unregistering /dev/watchdog (err=%d)\n", ret); + ida_simple_remove(&watchdog_ida, wdd->id); } EXPORT_SYMBOL_GPL(watchdog_unregister_device); +static int __init watchdog_init(void) +{ + return watchdog_dev_init(); +} + +static void __exit watchdog_exit(void) +{ + watchdog_dev_exit(); + ida_destroy(&watchdog_ida); +} + +subsys_initcall(watchdog_init); +module_exit(watchdog_exit); + MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>"); MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>"); MODULE_DESCRIPTION("WatchDog Timer Driver Core"); diff --git a/drivers/watchdog/watchdog_core.h b/drivers/watchdog/watchdog_core.h index 80503f22938..6c951418fca 100644 --- a/drivers/watchdog/watchdog_core.h +++ b/drivers/watchdog/watchdog_core.h @@ -26,8 +26,12 @@ * This material is provided "AS-IS" and at no charge. */ +#define MAX_DOGS 32 /* Maximum number of watchdog devices */ + /* * Functions/procedures to be called by the core */ extern int watchdog_dev_register(struct watchdog_device *); extern int watchdog_dev_unregister(struct watchdog_device *); +extern int __init watchdog_dev_init(void); +extern void __exit watchdog_dev_exit(void); diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index beaf9cb5541..3b22582bcb0 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -44,10 +44,10 @@ #include "watchdog_core.h" -/* make sure we only register one /dev/watchdog device */ -static unsigned long watchdog_dev_busy; +/* the dev_t structure to store the dynamically allocated watchdog devices */ +static dev_t watchdog_devt; /* the watchdog device behind /dev/watchdog */ -static struct watchdog_device *wdd; +static struct watchdog_device *old_wdd; /* * watchdog_ping: ping the watchdog. @@ -138,6 +138,7 @@ static int watchdog_stop(struct watchdog_device *wddev) static ssize_t watchdog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos) { + struct watchdog_device *wdd = file->private_data; size_t i; char c; @@ -177,6 +178,7 @@ static ssize_t watchdog_write(struct file *file, const char __user *data, static long watchdog_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { + struct watchdog_device *wdd = file->private_data; void __user *argp = (void __user *)arg; int __user *p = argp; unsigned int val; @@ -249,11 +251,11 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd, } /* - * watchdog_open: open the /dev/watchdog device. + * watchdog_open: open the /dev/watchdog* devices. * @inode: inode of device * @file: file handle to device * - * When the /dev/watchdog device gets opened, we start the watchdog. + * When the /dev/watchdog* device gets opened, we start the watchdog. * Watch out: the /dev/watchdog device is single open, so we make sure * it can only be opened once. */ @@ -261,6 +263,13 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd, static int watchdog_open(struct inode *inode, struct file *file) { int err = -EBUSY; + struct watchdog_device *wdd; + + /* Get the corresponding watchdog device */ + if (imajor(inode) == MISC_MAJOR) + wdd = old_wdd; + else + wdd = container_of(inode->i_cdev, struct watchdog_device, cdev); /* the watchdog is single open! */ if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status)) @@ -277,6 +286,8 @@ static int watchdog_open(struct inode *inode, struct file *file) if (err < 0) goto out_mod; + file->private_data = wdd; + /* dev/watchdog is a virtual (and thus non-seekable) filesystem */ return nonseekable_open(inode, file); @@ -288,9 +299,9 @@ out: } /* - * watchdog_release: release the /dev/watchdog device. - * @inode: inode of device - * @file: file handle to device + * watchdog_release: release the watchdog device. + * @inode: inode of device + * @file: file handle to device * * This is the code for when /dev/watchdog gets closed. We will only * stop the watchdog when we have received the magic char (and nowayout @@ -299,6 +310,7 @@ out: static int watchdog_release(struct inode *inode, struct file *file) { + struct watchdog_device *wdd = file->private_data; int err = -EBUSY; /* @@ -340,62 +352,87 @@ static struct miscdevice watchdog_miscdev = { }; /* - * watchdog_dev_register: + * watchdog_dev_register: register a watchdog device * @watchdog: watchdog device * - * Register a watchdog device as /dev/watchdog. /dev/watchdog - * is actually a miscdevice and thus we set it up like that. + * Register a watchdog device including handling the legacy + * /dev/watchdog node. /dev/watchdog is actually a miscdevice and + * thus we set it up like that. */ int watchdog_dev_register(struct watchdog_device *watchdog) { - int err; - - /* Only one device can register for /dev/watchdog */ - if (test_and_set_bit(0, &watchdog_dev_busy)) { - pr_err("only one watchdog can use /dev/watchdog\n"); - return -EBUSY; + int err, devno; + + if (watchdog->id == 0) { + err = misc_register(&watchdog_miscdev); + if (err != 0) { + pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n", + watchdog->info->identity, WATCHDOG_MINOR, err); + if (err == -EBUSY) + pr_err("%s: a legacy watchdog module is probably present.\n", + watchdog->info->identity); + return err; + } + old_wdd = watchdog; } - wdd = watchdog; - - err = misc_register(&watchdog_miscdev); - if (err != 0) { - pr_err("%s: cannot register miscdev on minor=%d (err=%d)\n", - watchdog->info->identity, WATCHDOG_MINOR, err); - goto out; + /* Fill in the data structures */ + devno = MKDEV(MAJOR(watchdog_devt), watchdog->id); + cdev_init(&watchdog->cdev, &watchdog_fops); + watchdog->cdev.owner = watchdog->ops->owner; + + /* Add the device */ + err = cdev_add(&watchdog->cdev, devno, 1); + if (err) { + pr_err("watchdog%d unable to add device %d:%d\n", + watchdog->id, MAJOR(watchdog_devt), watchdog->id); + if (watchdog->id == 0) { + misc_deregister(&watchdog_miscdev); + old_wdd = NULL; + } } - - return 0; - -out: - wdd = NULL; - clear_bit(0, &watchdog_dev_busy); return err; } /* - * watchdog_dev_unregister: + * watchdog_dev_unregister: unregister a watchdog device * @watchdog: watchdog device * - * Deregister the /dev/watchdog device. + * Unregister the watchdog and if needed the legacy /dev/watchdog device. */ int watchdog_dev_unregister(struct watchdog_device *watchdog) { - /* Check that a watchdog device was registered in the past */ - if (!test_bit(0, &watchdog_dev_busy) || !wdd) - return -ENODEV; - - /* We can only unregister the watchdog device that was registered */ - if (watchdog != wdd) { - pr_err("%s: watchdog was not registered as /dev/watchdog\n", - watchdog->info->identity); - return -ENODEV; + cdev_del(&watchdog->cdev); + if (watchdog->id == 0) { + misc_deregister(&watchdog_miscdev); + old_wdd = NULL; } - - misc_deregister(&watchdog_miscdev); - wdd = NULL; - clear_bit(0, &watchdog_dev_busy); return 0; } + +/* + * watchdog_dev_init: init dev part of watchdog core + * + * Allocate a range of chardev nodes to use for watchdog devices + */ + +int __init watchdog_dev_init(void) +{ + int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog"); + if (err < 0) + pr_err("watchdog: unable to allocate char dev region\n"); + return err; +} + +/* + * watchdog_dev_exit: exit dev part of watchdog core + * + * Release the range of chardev nodes used for watchdog devices + */ + +void __exit watchdog_dev_exit(void) +{ + unregister_chrdev_region(watchdog_devt, MAX_DOGS); +} diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h index 1984ea61057..508d56399e6 100644 --- a/include/linux/watchdog.h +++ b/include/linux/watchdog.h @@ -54,6 +54,8 @@ struct watchdog_info { #ifdef __KERNEL__ #include <linux/bitops.h> +#include <linux/device.h> +#include <linux/cdev.h> struct watchdog_ops; struct watchdog_device; @@ -89,6 +91,8 @@ struct watchdog_ops { /** struct watchdog_device - The structure that defines a watchdog device * + * @id: The watchdog's ID. (Allocated by watchdog_register_device) + * @cdev: The watchdog's Character device. * @info: Pointer to a watchdog_info structure. * @ops: Pointer to the list of watchdog operations. * @bootstatus: Status of the watchdog device at boot. @@ -105,6 +109,8 @@ struct watchdog_ops { * via the watchdog_set_drvdata and watchdog_get_drvdata helpers. */ struct watchdog_device { + int id; + struct cdev cdev; const struct watchdog_info *info; const struct watchdog_ops *ops; unsigned int bootstatus; |