diff options
Diffstat (limited to 'Documentation/watchdog')
| -rw-r--r-- | Documentation/watchdog/00-INDEX | 17 | ||||
| -rw-r--r-- | Documentation/watchdog/convert_drivers_to_kernel_api.txt | 218 | ||||
| -rw-r--r-- | Documentation/watchdog/src/watchdog-test.c | 20 | ||||
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 76 | ||||
| -rw-r--r-- | Documentation/watchdog/watchdog-parameters.txt | 20 |
5 files changed, 317 insertions, 34 deletions
diff --git a/Documentation/watchdog/00-INDEX b/Documentation/watchdog/00-INDEX deleted file mode 100644 index fc51128071c..00000000000 --- a/Documentation/watchdog/00-INDEX +++ /dev/null @@ -1,17 +0,0 @@ -00-INDEX - - this file. -hpwdt.txt - - information on the HP iLO2 NMI watchdog -pcwd-watchdog.txt - - documentation for Berkshire Products PC Watchdog ISA cards. -src/ - - directory holding watchdog related example programs. -watchdog-api.txt - - description of the Linux Watchdog driver API. -watchdog-kernel-api.txt - - description of the Linux WatchDog Timer Driver Core kernel API. -watchdog-parameters.txt - - information on driver parameters (for drivers other than - the ones that have driver-specific files here) -wdt.txt - - description of the Watchdog Timer Interfaces for Linux. diff --git a/Documentation/watchdog/convert_drivers_to_kernel_api.txt b/Documentation/watchdog/convert_drivers_to_kernel_api.txt new file mode 100644 index 00000000000..271b8850dde --- /dev/null +++ b/Documentation/watchdog/convert_drivers_to_kernel_api.txt @@ -0,0 +1,218 @@ +Converting old watchdog drivers to the watchdog framework +by Wolfram Sang <w.sang@pengutronix.de> +========================================================= + +Before the watchdog framework came into the kernel, every driver had to +implement the API on its own. Now, as the framework factored out the common +components, those drivers can be lightened making it a user of the framework. +This document shall guide you for this task. The necessary steps are described +as well as things to look out for. + + +Remove the file_operations struct +--------------------------------- + +Old drivers define their own file_operations for actions like open(), write(), +etc... These are now handled by the framework and just call the driver when +needed. So, in general, the 'file_operations' struct and assorted functions can +go. Only very few driver-specific details have to be moved to other functions. +Here is a overview of the functions and probably needed actions: + +- open: Everything dealing with resource management (file-open checks, magic + close preparations) can simply go. Device specific stuff needs to go to the + driver specific start-function. Note that for some drivers, the start-function + also serves as the ping-function. If that is the case and you need start/stop + to be balanced (clocks!), you are better off refactoring a separate start-function. + +- close: Same hints as for open apply. + +- write: Can simply go, all defined behaviour is taken care of by the framework, + i.e. ping on write and magic char ('V') handling. + +- ioctl: While the driver is allowed to have extensions to the IOCTL interface, + the most common ones are handled by the framework, supported by some assistance + from the driver: + + WDIOC_GETSUPPORT: + Returns the mandatory watchdog_info struct from the driver + + WDIOC_GETSTATUS: + Needs the status-callback defined, otherwise returns 0 + + WDIOC_GETBOOTSTATUS: + Needs the bootstatus member properly set. Make sure it is 0 if you + don't have further support! + + WDIOC_SETOPTIONS: + No preparations needed + + WDIOC_KEEPALIVE: + If wanted, options in watchdog_info need to have WDIOF_KEEPALIVEPING + set + + WDIOC_SETTIMEOUT: + Options in watchdog_info need to have WDIOF_SETTIMEOUT set + and a set_timeout-callback has to be defined. The core will also + do limit-checking, if min_timeout and max_timeout in the watchdog + device are set. All is optional. + + WDIOC_GETTIMEOUT: + No preparations needed + + WDIOC_GETTIMELEFT: + It needs get_timeleft() callback to be defined. Otherwise it + will return EOPNOTSUPP + + Other IOCTLs can be served using the ioctl-callback. Note that this is mainly + intended for porting old drivers; new drivers should not invent private IOCTLs. + Private IOCTLs are processed first. When the callback returns with + -ENOIOCTLCMD, the IOCTLs of the framework will be tried, too. Any other error + is directly given to the user. + +Example conversion: + +-static const struct file_operations s3c2410wdt_fops = { +- .owner = THIS_MODULE, +- .llseek = no_llseek, +- .write = s3c2410wdt_write, +- .unlocked_ioctl = s3c2410wdt_ioctl, +- .open = s3c2410wdt_open, +- .release = s3c2410wdt_release, +-}; + +Check the functions for device-specific stuff and keep it for later +refactoring. The rest can go. + + +Remove the miscdevice +--------------------- + +Since the file_operations are gone now, you can also remove the 'struct +miscdevice'. The framework will create it on watchdog_dev_register() called by +watchdog_register_device(). + +-static struct miscdevice s3c2410wdt_miscdev = { +- .minor = WATCHDOG_MINOR, +- .name = "watchdog", +- .fops = &s3c2410wdt_fops, +-}; + + +Remove obsolete includes and defines +------------------------------------ + +Because of the simplifications, a few defines are probably unused now. Remove +them. Includes can be removed, too. For example: + +- #include <linux/fs.h> +- #include <linux/miscdevice.h> (if MODULE_ALIAS_MISCDEV is not used) +- #include <linux/uaccess.h> (if no custom IOCTLs are used) + + +Add the watchdog operations +--------------------------- + +All possible callbacks are defined in 'struct watchdog_ops'. You can find it +explained in 'watchdog-kernel-api.txt' in this directory. start(), stop() and +owner must be set, the rest are optional. You will easily find corresponding +functions in the old driver. Note that you will now get a pointer to the +watchdog_device as a parameter to these functions, so you probably have to +change the function header. Other changes are most likely not needed, because +here simply happens the direct hardware access. If you have device-specific +code left from the above steps, it should be refactored into these callbacks. + +Here is a simple example: + ++static struct watchdog_ops s3c2410wdt_ops = { ++ .owner = THIS_MODULE, ++ .start = s3c2410wdt_start, ++ .stop = s3c2410wdt_stop, ++ .ping = s3c2410wdt_keepalive, ++ .set_timeout = s3c2410wdt_set_heartbeat, ++}; + +A typical function-header change looks like: + +-static void s3c2410wdt_keepalive(void) ++static int s3c2410wdt_keepalive(struct watchdog_device *wdd) + { +... ++ ++ return 0; + } + +... + +- s3c2410wdt_keepalive(); ++ s3c2410wdt_keepalive(&s3c2410_wdd); + + +Add the watchdog device +----------------------- + +Now we need to create a 'struct watchdog_device' and populate it with the +necessary information for the framework. The struct is also explained in detail +in 'watchdog-kernel-api.txt' in this directory. We pass it the mandatory +watchdog_info struct and the newly created watchdog_ops. Often, old drivers +have their own record-keeping for things like bootstatus and timeout using +static variables. Those have to be converted to use the members in +watchdog_device. Note that the timeout values are unsigned int. Some drivers +use signed int, so this has to be converted, too. + +Here is a simple example for a watchdog device: + ++static struct watchdog_device s3c2410_wdd = { ++ .info = &s3c2410_wdt_ident, ++ .ops = &s3c2410wdt_ops, ++}; + + +Handle the 'nowayout' feature +----------------------------- + +A few drivers use nowayout statically, i.e. there is no module parameter for it +and only CONFIG_WATCHDOG_NOWAYOUT determines if the feature is going to be +used. This needs to be converted by initializing the status variable of the +watchdog_device like this: + + .status = WATCHDOG_NOWAYOUT_INIT_STATUS, + +Most drivers, however, also allow runtime configuration of nowayout, usually +by adding a module parameter. The conversion for this would be something like: + + watchdog_set_nowayout(&s3c2410_wdd, nowayout); + +The module parameter itself needs to stay, everything else related to nowayout +can go, though. This will likely be some code in open(), close() or write(). + + +Register the watchdog device +---------------------------- + +Replace misc_register(&miscdev) with watchdog_register_device(&watchdog_dev). +Make sure the return value gets checked and the error message, if present, +still fits. Also convert the unregister case. + +- ret = misc_register(&s3c2410wdt_miscdev); ++ ret = watchdog_register_device(&s3c2410_wdd); + +... + +- misc_deregister(&s3c2410wdt_miscdev); ++ watchdog_unregister_device(&s3c2410_wdd); + + +Update the Kconfig-entry +------------------------ + +The entry for the driver now needs to select WATCHDOG_CORE: + ++ select WATCHDOG_CORE + + +Create a patch and send it to upstream +-------------------------------------- + +Make sure you understood Documentation/SubmittingPatches and send your patch to +linux-watchdog@vger.kernel.org. We are looking forward to it :) + diff --git a/Documentation/watchdog/src/watchdog-test.c b/Documentation/watchdog/src/watchdog-test.c index 63fdc34ceb9..3da822967ee 100644 --- a/Documentation/watchdog/src/watchdog-test.c +++ b/Documentation/watchdog/src/watchdog-test.c @@ -7,6 +7,7 @@ #include <string.h> #include <unistd.h> #include <fcntl.h> +#include <signal.h> #include <sys/ioctl.h> #include <linux/types.h> #include <linux/watchdog.h> @@ -29,6 +30,14 @@ static void keep_alive(void) * The main program. Run the program with "-d" to disable the card, * or "-e" to enable the card. */ + +static void term(int sig) +{ + close(fd); + fprintf(stderr, "Stopping watchdog ticks...\n"); + exit(0); +} + int main(int argc, char *argv[]) { int flags; @@ -47,26 +56,31 @@ int main(int argc, char *argv[]) ioctl(fd, WDIOC_SETOPTIONS, &flags); fprintf(stderr, "Watchdog card disabled.\n"); fflush(stderr); - exit(0); + goto end; } else if (!strncasecmp(argv[1], "-e", 2)) { flags = WDIOS_ENABLECARD; ioctl(fd, WDIOC_SETOPTIONS, &flags); fprintf(stderr, "Watchdog card enabled.\n"); fflush(stderr); - exit(0); + goto end; } else { fprintf(stderr, "-d to disable, -e to enable.\n"); fprintf(stderr, "run by itself to tick the card.\n"); fflush(stderr); - exit(0); + goto end; } } else { fprintf(stderr, "Watchdog Ticking Away!\n"); fflush(stderr); } + signal(SIGINT, term); + while(1) { keep_alive(); sleep(1); } +end: + close(fd); + return 0; } diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index 4f7c894244d..a0438f3957c 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: 22-Jul-2011 +Last reviewed: 12-Feb-2013 Wim Van Sebroeck <wim@iguana.be> @@ -39,6 +39,10 @@ watchdog_device structure. The watchdog device structure looks like this: struct watchdog_device { + int id; + struct cdev cdev; + struct device *dev; + struct device *parent; const struct watchdog_info *info; const struct watchdog_ops *ops; unsigned int bootstatus; @@ -46,10 +50,20 @@ struct watchdog_device { unsigned int min_timeout; unsigned int max_timeout; void *driver_data; + struct mutex lock; unsigned long status; }; 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. +* dev: device under the watchdog class (created by watchdog_register_device). +* parent: set this to the parent device (or NULL) before calling + 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. @@ -59,8 +73,9 @@ It contains following fields: * bootstatus: status of the device after booting (reported with watchdog WDIOF_* status bits). * driver_data: a pointer to the drivers private data of a watchdog device. - This data should only be accessed via the watchdog_set_drvadata and + This data should only be accessed via the watchdog_set_drvdata and watchdog_get_drvdata routines. +* lock: Mutex for WatchDog Timer Driver Core internal use only. * status: this field contains a number of status bits that give extra information about the status of the device (Like: is the watchdog timer running/active, is the nowayout bit set, is the device opened via @@ -77,6 +92,9 @@ struct watchdog_ops { int (*ping)(struct watchdog_device *); unsigned int (*status)(struct watchdog_device *); int (*set_timeout)(struct watchdog_device *, unsigned int); + unsigned int (*get_timeleft)(struct watchdog_device *); + void (*ref)(struct watchdog_device *); + void (*unref)(struct watchdog_device *); long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long); }; @@ -84,6 +102,21 @@ It is important that you first define the module owner of the watchdog timer driver's operations. This module owner will be used to lock the module when the watchdog is active. (This to avoid a system crash when you unload the module and /dev/watchdog is still open). + +If the watchdog_device struct is dynamically allocated, just locking the module +is not enough and a driver also needs to define the ref and unref operations to +ensure the structure holding the watchdog_device does not go away. + +The simplest (and usually sufficient) implementation of this is to: +1) Add a kref struct to the same structure which is holding the watchdog_device +2) Define a release callback for the kref which frees the struct holding both +3) Call kref_init on this kref *before* calling watchdog_register_device() +4) Define a ref operation calling kref_get on this kref +5) Define a unref operation calling kref_put on this kref +6) When it is time to cleanup: + * Do not kfree() the struct holding both, the last kref_put will do this! + * *After* calling watchdog_unregister_device() call kref_put on the kref + Some operations are mandatory and some are optional. The mandatory operations are: * start: this is a pointer to the routine that starts the watchdog timer @@ -117,11 +150,17 @@ they are supported. These optional routines/operations are: status of the device is reported with watchdog WDIOF_* status flags/bits. * set_timeout: this routine checks and changes the timeout of the watchdog timer device. It returns 0 on success, -EINVAL for "parameter out of range" - and -EIO for "could not write value to the watchdog". On success the timeout - value of the watchdog_device will be changed to the value that was just used - to re-program the watchdog timer device. + and -EIO for "could not write value to the watchdog". On success this + routine should set the timeout value of the watchdog_device to the + achieved timeout value (which may be different from the requested one + because the watchdog does not necessarily has a 1 second resolution). (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the watchdog's info structure). +* get_timeleft: this routines returns the time that's left before a reset. +* ref: the operation that calls kref_get on the kref of a dynamically + allocated watchdog_device struct. +* unref: the operation that calls kref_put on the kref of a dynamically + allocated watchdog_device struct. * ioctl: if this routine is present then it will be called first before we do our own internal ioctl call handling. This routine should return -ENOIOCTLCMD if a command is not supported. The parameters that are passed to the ioctl @@ -141,6 +180,19 @@ bit-operations. The status bits that are defined are: (This bit should only be used by the WatchDog Timer Driver Core). * WDOG_NO_WAY_OUT: this bit stores the nowayout setting for the watchdog. If this bit is set then the watchdog timer will not be able to stop. +* WDOG_UNREGISTERED: this bit gets set by the WatchDog Timer Driver Core + after calling watchdog_unregister_device, and then checked before calling + any watchdog_ops, so that you can be sure that no operations (other then + unref) will get called after unregister, even if userspace still holds a + reference to /dev/watchdog + + To set the WDOG_NO_WAY_OUT status bit (before registering your watchdog + timer device) you can either: + * set it statically in your watchdog_device struct with + .status = WATCHDOG_NOWAYOUT_INIT_STATUS, + (this will set the value the same as CONFIG_WATCHDOG_NOWAYOUT) or + * use the following helper function: + static inline void watchdog_set_nowayout(struct watchdog_device *wdd, int nowayout) Note: The WatchDog Timer Driver Core supports the magic close feature and the nowayout feature. To use the magic close feature you must set the @@ -159,4 +211,16 @@ driver specific data to and a pointer to the data itself. The watchdog_get_drvdata function allows you to retrieve driver specific data. The argument of this function is the watchdog device where you want to retrieve -data from. The function retruns the pointer to the driver specific data. +data from. The function returns the pointer to the driver specific data. + +To initialize the timeout field, the following function can be used: + +extern int watchdog_init_timeout(struct watchdog_device *wdd, + unsigned int timeout_parm, struct device *dev); + +The watchdog_init_timeout function allows you to initialize the timeout field +using the module timeout parameter or by retrieving the timeout-sec property from +the device tree (if the module timeout parameter is invalid). Best practice is +to set the default timeout value as timeout value in the watchdog_device and +then use this function to set the user "preferred" timeout value. +This routine returns zero on success and a negative errno code for failure. diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt index 17ddd822b45..692791cc674 100644 --- a/Documentation/watchdog/watchdog-parameters.txt +++ b/Documentation/watchdog/watchdog-parameters.txt @@ -78,6 +78,11 @@ wd0_timeout: Default watchdog0 timeout in 1/10secs wd1_timeout: Default watchdog1 timeout in 1/10secs wd2_timeout: Default watchdog2 timeout in 1/10secs ------------------------------------------------- +da9052wdt: +timeout: Watchdog timeout in seconds. 2<= timeout <=131, default=2.048s +nowayout: Watchdog cannot be stopped once started + (default=kernel config parameter) +------------------------------------------------- davinci_wdt: heartbeat: Watchdog heartbeat period in seconds from 1 to 600, default 60 ------------------------------------------------- @@ -145,6 +150,8 @@ nowayout: Disable watchdog shutdown on close ------------------------------------------------- it87_wdt: nogameport: Forbid the activation of game port, default=0 +nocir: Forbid the use of CIR (workaround for some buggy setups); set to 1 if +system resets despite watchdog daemon running, default=0 exclusive: Watchdog exclusive device open, default=1 timeout: Watchdog timeout in seconds, default=60 testmode: Watchdog test mode (1 = no reboot), default=0 @@ -189,14 +196,6 @@ reset: Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset nowayout: Watchdog cannot be stopped once started (default=kernel config parameter) ------------------------------------------------- -mpcore_wdt: -mpcore_margin: MPcore timer margin in seconds. - (0 < mpcore_margin < 65536, default=60) -nowayout: Watchdog cannot be stopped once started - (default=kernel config parameter) -mpcore_noboot: MPcore watchdog action, set to 1 to ignore reboots, - 0 to reboot (default=0 -------------------------------------------------- mv64x60_wdt: nowayout: Watchdog cannot be stopped once started (default=kernel config parameter) @@ -328,6 +327,11 @@ soft_noboot: Softdog action, set to 1 to ignore reboots, 0 to reboot stmp3xxx_wdt: heartbeat: Watchdog heartbeat period in seconds from 1 to 4194304, default 19 ------------------------------------------------- +tegra_wdt: +heartbeat: Watchdog heartbeats in seconds. (default = 120) +nowayout: Watchdog cannot be stopped once started + (default=kernel config parameter) +------------------------------------------------- ts72xx_wdt: timeout: Watchdog timeout in seconds. (1 <= timeout <= 8, default=8) nowayout: Disable watchdog shutdown on close |