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[206.116.172.62]) by smtp.gmail.com with ESMTPSA id 185sm63183322pfd.125.2019.07.29.20.50.55 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 29 Jul 2019 20:50:56 -0700 (PDT) From: Mark Balantzyan To: linux@roeck-us.net Cc: wim@linux-watchdog.org, linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org, andrianov@ispras.ru, Mark Balantzyan Subject: [PATCH] Revision of pc87413_wdt driver to use watchdog subsystem Date: Mon, 29 Jul 2019 20:50:50 -0700 Message-Id: <20190730035050.15321-1-mbalant3@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch rewrites the pc87413_wdt driver to use the watchdog subsystem. In doing so, it also addresses a potential race condition owing from the swc_base_addr variable being used before being set. Signed-off-by: Mark Balantzyan --- drivers/watchdog/Kconfig | 1 + drivers/watchdog/pc87413_wdt.c | 294 +++++---------------------------- 2 files changed, 39 insertions(+), 256 deletions(-) diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index 9af07fd9..84a7326d 100644 --- a/drivers/watchdog/Kconfig +++ b/drivers/watchdog/Kconfig @@ -1166,6 +1166,7 @@ config SCx200_WDT config PC87413_WDT tristate "NS PC87413 watchdog" + select WATCHDOG_CORE depends on X86 ---help--- This is the driver for the hardware watchdog on the PC87413 chipset diff --git a/drivers/watchdog/pc87413_wdt.c b/drivers/watchdog/pc87413_wdt.c index 06a892e3..d1d32771 100644 --- a/drivers/watchdog/pc87413_wdt.c +++ b/drivers/watchdog/pc87413_wdt.c @@ -22,12 +22,10 @@ #include #include -#include #include #include #include #include -#include #include #include #include @@ -65,7 +63,6 @@ static char expect_close; /* is the close expected? */ static DEFINE_SPINLOCK(io_lock); /* to guard us from io races */ -static bool nowayout = WATCHDOG_NOWAYOUT; /* -- Low level function ----------------------------------------*/ @@ -216,41 +213,32 @@ static inline void pc87413_disable_sw_wd_trg(void) /* -- Higher level functions ------------------------------------*/ -/* Enable the watchdog */ +/* Enable/start the watchdog */ -static void pc87413_enable(void) +static void pc87413_start(void) { - spin_lock(&io_lock); - pc87413_swc_bank3(); pc87413_programm_wdto(timeout); pc87413_enable_wden(); pc87413_enable_sw_wd_tren(); pc87413_enable_sw_wd_trg(); - spin_unlock(&io_lock); } -/* Disable the watchdog */ +/* Disable/stop the watchdog */ -static void pc87413_disable(void) +static void pc87413_stop(void) { - spin_lock(&io_lock); - pc87413_swc_bank3(); pc87413_disable_sw_wd_tren(); pc87413_disable_sw_wd_trg(); pc87413_programm_wdto(0); - - spin_unlock(&io_lock); } -/* Refresh the watchdog */ +/* Refresh/keepalive the watchdog */ -static void pc87413_refresh(void) +static void pc87413_keepalive(struct watchdog_device *wdd) { - spin_lock(&io_lock); - pc87413_swc_bank3(); pc87413_disable_sw_wd_tren(); pc87413_disable_sw_wd_trg(); @@ -258,195 +246,11 @@ static void pc87413_refresh(void) pc87413_enable_wden(); pc87413_enable_sw_wd_tren(); pc87413_enable_sw_wd_trg(); - - spin_unlock(&io_lock); -} - -/* -- File operations -------------------------------------------*/ - -/** - * pc87413_open: - * @inode: inode of device - * @file: file handle to device - * - */ - -static int pc87413_open(struct inode *inode, struct file *file) -{ - /* /dev/watchdog can only be opened once */ - - if (test_and_set_bit(0, &timer_enabled)) - return -EBUSY; - - if (nowayout) - __module_get(THIS_MODULE); - - /* Reload and activate timer */ - pc87413_refresh(); - - pr_info("Watchdog enabled. Timeout set to %d minute(s).\n", timeout); - - return nonseekable_open(inode, file); -} - -/** - * pc87413_release: - * @inode: inode to board - * @file: file handle to board - * - * The watchdog has a configurable API. There is a religious dispute - * between people who want their watchdog to be able to shut down and - * those who want to be sure if the watchdog manager dies the machine - * reboots. In the former case we disable the counters, in the latter - * case you have to open it again very soon. - */ - -static int pc87413_release(struct inode *inode, struct file *file) -{ - /* Shut off the timer. */ - - if (expect_close == 42) { - pc87413_disable(); - pr_info("Watchdog disabled, sleeping again...\n"); - } else { - pr_crit("Unexpected close, not stopping watchdog!\n"); - pc87413_refresh(); - } - clear_bit(0, &timer_enabled); - expect_close = 0; return 0; } -/** - * pc87413_status: - * - * return, if the watchdog is enabled (timeout is set...) - */ - - -static int pc87413_status(void) -{ - return 0; /* currently not supported */ -} - -/** - * pc87413_write: - * @file: file handle to the watchdog - * @data: data buffer to write - * @len: length in bytes - * @ppos: pointer to the position to write. No seeks allowed - * - * A write to a watchdog device is defined as a keepalive signal. Any - * write of data will do, as we we don't define content meaning. - */ - -static ssize_t pc87413_write(struct file *file, const char __user *data, - size_t len, loff_t *ppos) -{ - /* See if we got the magic character 'V' and reload the timer */ - if (len) { - if (!nowayout) { - size_t i; - - /* reset expect flag */ - expect_close = 0; - - /* scan to see whether or not we got the - magic character */ - for (i = 0; i != len; i++) { - char c; - if (get_user(c, data + i)) - return -EFAULT; - if (c == 'V') - expect_close = 42; - } - } - - /* someone wrote to us, we should reload the timer */ - pc87413_refresh(); - } - return len; -} - -/** - * pc87413_ioctl: - * @file: file handle to the device - * @cmd: watchdog command - * @arg: argument pointer - * - * The watchdog API defines a common set of functions for all watchdogs - * according to their available features. We only actually usefully support - * querying capabilities and current status. - */ - -static long pc87413_ioctl(struct file *file, unsigned int cmd, - unsigned long arg) -{ - int new_timeout; - - union { - struct watchdog_info __user *ident; - int __user *i; - } uarg; - - static const struct watchdog_info ident = { - .options = WDIOF_KEEPALIVEPING | - WDIOF_SETTIMEOUT | - WDIOF_MAGICCLOSE, - .firmware_version = 1, - .identity = "PC87413(HF/F) watchdog", - }; - - uarg.i = (int __user *)arg; - - switch (cmd) { - case WDIOC_GETSUPPORT: - return copy_to_user(uarg.ident, &ident, - sizeof(ident)) ? -EFAULT : 0; - case WDIOC_GETSTATUS: - return put_user(pc87413_status(), uarg.i); - case WDIOC_GETBOOTSTATUS: - return put_user(0, uarg.i); - case WDIOC_SETOPTIONS: - { - int options, retval = -EINVAL; - if (get_user(options, uarg.i)) - return -EFAULT; - if (options & WDIOS_DISABLECARD) { - pc87413_disable(); - retval = 0; - } - if (options & WDIOS_ENABLECARD) { - pc87413_enable(); - retval = 0; - } - return retval; - } - case WDIOC_KEEPALIVE: - pc87413_refresh(); -#ifdef DEBUG - pr_info(DPFX "keepalive\n"); -#endif - return 0; - case WDIOC_SETTIMEOUT: - if (get_user(new_timeout, uarg.i)) - return -EFAULT; - /* the API states this is given in secs */ - new_timeout /= 60; - if (new_timeout < 0 || new_timeout > MAX_TIMEOUT) - return -EINVAL; - timeout = new_timeout; - pc87413_refresh(); - /* fall through and return the new timeout... */ - case WDIOC_GETTIMEOUT: - new_timeout = timeout * 60; - return put_user(new_timeout, uarg.i); - default: - return -ENOTTY; - } -} -/* -- Notifier funtions -----------------------------------------*/ +/* -- Notifier functions -----------------------------------------*/ /** * notify_sys: @@ -460,37 +264,43 @@ static long pc87413_ioctl(struct file *file, unsigned int cmd, * trust me - if it happens it does suck. */ -static int pc87413_notify_sys(struct notifier_block *this, - unsigned long code, - void *unused) + +/* -- Module's structures ---------------------------------------*/ + + +static int watchdog_restart_notifier(struct notifier_block *nb, + unsigned long code, void *data) { - if (code == SYS_DOWN || code == SYS_HALT) - /* Turn the card off */ - pc87413_disable(); + struct watchdog_device *wdd = container_of(nb, struct watchdog_device, + reboot_nb); + + if (code == SYS_DOWN || code == SYS_HALT) { + int ret; + + ret = wdd->ops->stop(wdd); + if (ret) + return NOTIFY_BAD; + } + return NOTIFY_DONE; } -/* -- Module's structures ---------------------------------------*/ -static const struct file_operations pc87413_fops = { - .owner = THIS_MODULE, - .llseek = no_llseek, - .write = pc87413_write, - .unlocked_ioctl = pc87413_ioctl, - .open = pc87413_open, - .release = pc87413_release, -}; -static struct notifier_block pc87413_notifier = { - .notifier_call = pc87413_notify_sys, +static struct watchdog_ops pc87413wdt_ops = { + .owner = THIS_MODULE, + .start = pc87413_start, + .stop = pc87413_stop, + .ping = pc87413_keepalive, + .restart = watchdog_restart_notifier, }; -static struct miscdevice pc87413_miscdev = { - .minor = WATCHDOG_MINOR, - .name = "watchdog", - .fops = &pc87413_fops, +static struct watchdog_device pc87413wdt_wdd = { + .ops = &pc87413wdt_ops, + .status = WATCHDOG_NOWAYOUT_INIT_STATUS, }; + /* -- Module init functions -------------------------------------*/ /** @@ -498,7 +308,6 @@ static struct miscdevice pc87413_miscdev = { * * Set up the WDT watchdog board. All we have to do is grab the * resources we require and bitch if anyone beat us to them. - * The open() function will actually kick the board off. */ static int __init pc87413_init(void) @@ -511,16 +320,7 @@ static int __init pc87413_init(void) if (!request_muxed_region(io, 2, MODNAME)) return -EBUSY; - ret = register_reboot_notifier(&pc87413_notifier); - if (ret != 0) - pr_err("cannot register reboot notifier (err=%d)\n", ret); - - ret = misc_register(&pc87413_miscdev); - if (ret != 0) { - pr_err("cannot register miscdev on minor=%d (err=%d)\n", - WATCHDOG_MINOR, ret); - goto reboot_unreg; - } + ret = watchdog_register_device(&pc87413wdt_wdd); pr_info("initialized. timeout=%d min\n", timeout); pc87413_select_wdt_out(); @@ -533,17 +333,12 @@ static int __init pc87413_init(void) goto misc_unreg; } - pc87413_enable(); - release_region(io, 2); + pc87413_keepalive(&pc87413wdt_wdd); return 0; misc_unreg: - misc_deregister(&pc87413_miscdev); -reboot_unreg: - unregister_reboot_notifier(&pc87413_notifier); - release_region(io, 2); - return ret; + watchdog_unregister_device(&pc87413wdt_wdd); } /** @@ -558,14 +353,7 @@ reboot_unreg: static void __exit pc87413_exit(void) { - /* Stop the timer before we leave */ - if (!nowayout) { - pc87413_disable(); - pr_info("Watchdog disabled\n"); - } - - misc_deregister(&pc87413_miscdev); - unregister_reboot_notifier(&pc87413_notifier); + watchdog_unregister_device(&pc87413wdt_wdd); release_region(swc_base_addr, 0x20); pr_info("watchdog component driver removed\n"); @@ -587,9 +375,3 @@ module_param(timeout, int, 0); MODULE_PARM_DESC(timeout, "Watchdog timeout in minutes (default=" __MODULE_STRING(DEFAULT_TIMEOUT) ")."); - -module_param(nowayout, bool, 0); -MODULE_PARM_DESC(nowayout, - "Watchdog cannot be stopped once started (default=" - __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); -