diff options
Diffstat (limited to 'drivers/watchdog/bfin_wdt.c')
| -rw-r--r-- | drivers/watchdog/bfin_wdt.c | 476 |
1 files changed, 476 insertions, 0 deletions
diff --git a/drivers/watchdog/bfin_wdt.c b/drivers/watchdog/bfin_wdt.c new file mode 100644 index 000000000..aa4d2e8a8 --- /dev/null +++ b/drivers/watchdog/bfin_wdt.c @@ -0,0 +1,476 @@ +/* + * 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) ")"); |