/* * Blackfin On-Chip Watchdog Driver * * Originally based on softdog.c * Copyright 2006-2010 Analog Devices Inc. * Copyright 2006-2007 Michele d'Amico * Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk> * * Enter bugs at http://blackfin.uclinux.org/ * * Licensed under the GPL-2 or later. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/platform_device.h> #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/types.h> #include <linux/timer.h> #include <linux/miscdevice.h> #include <linux/watchdog.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/interrupt.h> #include <linux/uaccess.h> #include <asm/blackfin.h> #include <asm/bfin_watchdog.h> #define stamp(fmt, args...) \ pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args) #define stampit() stamp("here i am") #define WATCHDOG_NAME "bfin-wdt" /* The BF561 has two watchdogs (one per core), but since Linux * only runs on core A, we'll just work with that one. */ #ifdef BF561_FAMILY # define bfin_read_WDOG_CTL() bfin_read_WDOGA_CTL() # define bfin_read_WDOG_CNT() bfin_read_WDOGA_CNT() # define bfin_read_WDOG_STAT() bfin_read_WDOGA_STAT() # define bfin_write_WDOG_CTL(x) bfin_write_WDOGA_CTL(x) # define bfin_write_WDOG_CNT(x) bfin_write_WDOGA_CNT(x) # define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x) #endif /* some defaults */ #define WATCHDOG_TIMEOUT 20 static unsigned int timeout = WATCHDOG_TIMEOUT; static bool nowayout = WATCHDOG_NOWAYOUT; static const struct watchdog_info bfin_wdt_info; static unsigned long open_check; static char expect_close; static DEFINE_SPINLOCK(bfin_wdt_spinlock); /** * bfin_wdt_keepalive - Keep the Userspace Watchdog Alive * * The Userspace watchdog got a KeepAlive: schedule the next timeout. */ static int bfin_wdt_keepalive(void) { stampit(); bfin_write_WDOG_STAT(0); return 0; } /** * bfin_wdt_stop - Stop the Watchdog * * Stops the on-chip watchdog. */ static int bfin_wdt_stop(void) { stampit(); bfin_write_WDOG_CTL(WDEN_DISABLE); return 0; } /** * bfin_wdt_start - Start the Watchdog * * Starts the on-chip watchdog. Automatically loads WDOG_CNT * into WDOG_STAT for us. */ static int bfin_wdt_start(void) { stampit(); bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET); return 0; } /** * bfin_wdt_running - Check Watchdog status * * See if the watchdog is running. */ static int bfin_wdt_running(void) { stampit(); return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE); } /** * bfin_wdt_set_timeout - Set the Userspace Watchdog timeout * @t: new timeout value (in seconds) * * Translate the specified timeout in seconds into System Clock * terms which is what the on-chip Watchdog requires. */ static int bfin_wdt_set_timeout(unsigned long t) { u32 cnt, max_t, sclk; unsigned long flags; sclk = get_sclk(); max_t = -1 / sclk; cnt = t * sclk; stamp("maxtimeout=%us newtimeout=%lus (cnt=%#x)", max_t, t, cnt); if (t > max_t) { pr_warn("timeout value is too large\n"); return -EINVAL; } spin_lock_irqsave(&bfin_wdt_spinlock, flags); { int run = bfin_wdt_running(); bfin_wdt_stop(); bfin_write_WDOG_CNT(cnt); if (run) bfin_wdt_start(); } spin_unlock_irqrestore(&bfin_wdt_spinlock, flags); timeout = t; return 0; } /** * bfin_wdt_open - Open the Device * @inode: inode of device * @file: file handle of device * * Watchdog device is opened and started. */ static int bfin_wdt_open(struct inode *inode, struct file *file) { stampit(); if (test_and_set_bit(0, &open_check)) return -EBUSY; if (nowayout) __module_get(THIS_MODULE); bfin_wdt_keepalive(); bfin_wdt_start(); return nonseekable_open(inode, file); } /** * bfin_wdt_close - Close the Device * @inode: inode of device * @file: file handle of device * * Watchdog device is closed and stopped. */ static int bfin_wdt_release(struct inode *inode, struct file *file) { stampit(); if (expect_close == 42) bfin_wdt_stop(); else { pr_crit("Unexpected close, not stopping watchdog!\n"); bfin_wdt_keepalive(); } expect_close = 0; clear_bit(0, &open_check); return 0; } /** * bfin_wdt_write - Write to Device * @file: file handle of device * @buf: buffer to write * @count: length of buffer * @ppos: offset * * Pings the watchdog on write. */ static ssize_t bfin_wdt_write(struct file *file, const char __user *data, size_t len, loff_t *ppos) { stampit(); if (len) { if (!nowayout) { size_t i; /* In case it was set long ago */ expect_close = 0; for (i = 0; i != len; i++) { char c; if (get_user(c, data + i)) return -EFAULT; if (c == 'V') expect_close = 42; } } bfin_wdt_keepalive(); } return len; } /** * bfin_wdt_ioctl - Query Device * @file: file handle of device * @cmd: watchdog command * @arg: argument * * Query basic information from the device or ping it, as outlined by the * watchdog API. */ static long bfin_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { void __user *argp = (void __user *)arg; int __user *p = argp; stampit(); switch (cmd) { case WDIOC_GETSUPPORT: if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info))) return -EFAULT; else return 0; case WDIOC_GETSTATUS: case WDIOC_GETBOOTSTATUS: return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p); case WDIOC_SETOPTIONS: { unsigned long flags; int options, ret = -EINVAL; if (get_user(options, p)) return -EFAULT; spin_lock_irqsave(&bfin_wdt_spinlock, flags); if (options & WDIOS_DISABLECARD) { bfin_wdt_stop(); ret = 0; } if (options & WDIOS_ENABLECARD) { bfin_wdt_start(); ret = 0; } spin_unlock_irqrestore(&bfin_wdt_spinlock, flags); return ret; } case WDIOC_KEEPALIVE: bfin_wdt_keepalive(); return 0; case WDIOC_SETTIMEOUT: { int new_timeout; if (get_user(new_timeout, p)) return -EFAULT; if (bfin_wdt_set_timeout(new_timeout)) return -EINVAL; } /* Fall */ case WDIOC_GETTIMEOUT: return put_user(timeout, p); default: return -ENOTTY; } } #ifdef CONFIG_PM static int state_before_suspend; /** * bfin_wdt_suspend - suspend the watchdog * @pdev: device being suspended * @state: requested suspend state * * Remember if the watchdog was running and stop it. * TODO: is this even right? Doesn't seem to be any * standard in the watchdog world ... */ static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state) { stampit(); state_before_suspend = bfin_wdt_running(); bfin_wdt_stop(); return 0; } /** * bfin_wdt_resume - resume the watchdog * @pdev: device being resumed * * If the watchdog was running, turn it back on. */ static int bfin_wdt_resume(struct platform_device *pdev) { stampit(); if (state_before_suspend) { bfin_wdt_set_timeout(timeout); bfin_wdt_start(); } return 0; } #else # define bfin_wdt_suspend NULL # define bfin_wdt_resume NULL #endif static const struct file_operations bfin_wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = bfin_wdt_write, .unlocked_ioctl = bfin_wdt_ioctl, .open = bfin_wdt_open, .release = bfin_wdt_release, }; static struct miscdevice bfin_wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &bfin_wdt_fops, }; static const struct watchdog_info bfin_wdt_info = { .identity = "Blackfin Watchdog", .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, }; /** * bfin_wdt_probe - Initialize module * * Registers the misc device. Actual device * initialization is handled by bfin_wdt_open(). */ static int bfin_wdt_probe(struct platform_device *pdev) { int ret; ret = misc_register(&bfin_wdt_miscdev); if (ret) { pr_err("cannot register miscdev on minor=%d (err=%d)\n", WATCHDOG_MINOR, ret); return ret; } pr_info("initialized: timeout=%d sec (nowayout=%d)\n", timeout, nowayout); return 0; } /** * bfin_wdt_remove - Initialize module * * Unregisters the misc device. Actual device * deinitialization is handled by bfin_wdt_close(). */ static int bfin_wdt_remove(struct platform_device *pdev) { misc_deregister(&bfin_wdt_miscdev); return 0; } /** * bfin_wdt_shutdown - Soft Shutdown Handler * * Handles the soft shutdown event. */ static void bfin_wdt_shutdown(struct platform_device *pdev) { stampit(); bfin_wdt_stop(); } static struct platform_device *bfin_wdt_device; static struct platform_driver bfin_wdt_driver = { .probe = bfin_wdt_probe, .remove = bfin_wdt_remove, .shutdown = bfin_wdt_shutdown, .suspend = bfin_wdt_suspend, .resume = bfin_wdt_resume, .driver = { .name = WATCHDOG_NAME, }, }; /** * bfin_wdt_init - Initialize module * * Checks the module params and registers the platform device & driver. * Real work is in the platform probe function. */ static int __init bfin_wdt_init(void) { int ret; stampit(); /* Check that the timeout value is within range */ if (bfin_wdt_set_timeout(timeout)) return -EINVAL; /* Since this is an on-chip device and needs no board-specific * resources, we'll handle all the platform device stuff here. */ ret = platform_driver_register(&bfin_wdt_driver); if (ret) { pr_err("unable to register driver\n"); return ret; } bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME, -1, NULL, 0); if (IS_ERR(bfin_wdt_device)) { pr_err("unable to register device\n"); platform_driver_unregister(&bfin_wdt_driver); return PTR_ERR(bfin_wdt_device); } return 0; } /** * bfin_wdt_exit - Deinitialize module * * Back out the platform device & driver steps. Real work is in the * platform remove function. */ static void __exit bfin_wdt_exit(void) { platform_device_unregister(bfin_wdt_device); platform_driver_unregister(&bfin_wdt_driver); } module_init(bfin_wdt_init); module_exit(bfin_wdt_exit); MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>"); MODULE_DESCRIPTION("Blackfin Watchdog Device Driver"); MODULE_LICENSE("GPL"); module_param(timeout, uint, 0); MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");