diff options
Diffstat (limited to 'drivers/watchdog/sc520_wdt.c')
| -rw-r--r-- | drivers/watchdog/sc520_wdt.c | 431 |
1 files changed, 431 insertions, 0 deletions
diff --git a/drivers/watchdog/sc520_wdt.c b/drivers/watchdog/sc520_wdt.c new file mode 100644 index 000000000..ca65468f4 --- /dev/null +++ b/drivers/watchdog/sc520_wdt.c @@ -0,0 +1,431 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * AMD Elan SC520 processor Watchdog Timer driver + * + * Based on acquirewdt.c by Alan Cox, + * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net> + * + * The authors do NOT admit liability nor provide warranty for + * any of this software. This material is provided "AS-IS" in + * the hope that it may be useful for others. + * + * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net> + * 9/27 - 2001 [Initial release] + * + * Additional fixes Alan Cox + * - Fixed formatting + * - Removed debug printks + * - Fixed SMP built kernel deadlock + * - Switched to private locks not lock_kernel + * - Used ioremap/writew/readw + * - Added NOWAYOUT support + * 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com> + * - Change comments + * - Eliminate fop_llseek + * - Change CONFIG_WATCHDOG_NOWAYOUT semantics + * - Add KERN_* tags to printks + * - fix possible wdt_is_open race + * - Report proper capabilities in watchdog_info + * - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT, + * GETTIMEOUT, SETOPTIONS} ioctls + * 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be> + * - cleanup of trailing spaces + * - added extra printk's for startup problems + * - use module_param + * - made timeout (the emulated heartbeat) a module_param + * - made the keepalive ping an internal subroutine + * 3/27 - 2004 Changes by Sean Young <sean@mess.org> + * - set MMCR_BASE to 0xfffef000 + * - CBAR does not need to be read + * - removed debugging printks + * + * This WDT driver is different from most other Linux WDT + * drivers in that the driver will ping the watchdog by itself, + * because this particular WDT has a very short timeout (1.6 + * seconds) and it would be insane to count on any userspace + * daemon always getting scheduled within that time frame. + * + * This driver uses memory mapped IO, and spinlock. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#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/ioport.h> +#include <linux/notifier.h> +#include <linux/reboot.h> +#include <linux/init.h> +#include <linux/jiffies.h> +#include <linux/io.h> +#include <linux/uaccess.h> + + +/* + * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7) + * + * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s + * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s + * + * We will program the SC520 watchdog for a timeout of 2.01s. + * If we reset the watchdog every ~250ms we should be safe. + */ + +#define WDT_INTERVAL (HZ/4+1) + +/* + * We must not require too good response from the userspace daemon. + * Here we require the userspace daemon to send us a heartbeat + * char to /dev/watchdog every 30 seconds. + */ + +#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ +/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ +static int timeout = WATCHDOG_TIMEOUT; +module_param(timeout, int, 0); +MODULE_PARM_DESC(timeout, + "Watchdog timeout in seconds. (1 <= timeout <= 3600, default=" + __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); + +static bool nowayout = WATCHDOG_NOWAYOUT; +module_param(nowayout, bool, 0); +MODULE_PARM_DESC(nowayout, + "Watchdog cannot be stopped once started (default=" + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); + +/* + * AMD Elan SC520 - Watchdog Timer Registers + */ +#define MMCR_BASE 0xfffef000 /* The default base address */ +#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */ + +/* WDT Control Register bit definitions */ +#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */ +#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */ +#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */ +#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */ +#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */ +#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */ +#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */ +#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */ +#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */ +#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */ +#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */ + +static __u16 __iomem *wdtmrctl; + +static void wdt_timer_ping(struct timer_list *); +static DEFINE_TIMER(timer, wdt_timer_ping); +static unsigned long next_heartbeat; +static unsigned long wdt_is_open; +static char wdt_expect_close; +static DEFINE_SPINLOCK(wdt_spinlock); + +/* + * Whack the dog + */ + +static void wdt_timer_ping(struct timer_list *unused) +{ + /* If we got a heartbeat pulse within the WDT_US_INTERVAL + * we agree to ping the WDT + */ + if (time_before(jiffies, next_heartbeat)) { + /* Ping the WDT */ + spin_lock(&wdt_spinlock); + writew(0xAAAA, wdtmrctl); + writew(0x5555, wdtmrctl); + spin_unlock(&wdt_spinlock); + + /* Re-set the timer interval */ + mod_timer(&timer, jiffies + WDT_INTERVAL); + } else + pr_warn("Heartbeat lost! Will not ping the watchdog\n"); +} + +/* + * Utility routines + */ + +static void wdt_config(int writeval) +{ + unsigned long flags; + + /* buy some time (ping) */ + spin_lock_irqsave(&wdt_spinlock, flags); + readw(wdtmrctl); /* ensure write synchronization */ + writew(0xAAAA, wdtmrctl); + writew(0x5555, wdtmrctl); + /* unlock WDT = make WDT configuration register writable one time */ + writew(0x3333, wdtmrctl); + writew(0xCCCC, wdtmrctl); + /* write WDT configuration register */ + writew(writeval, wdtmrctl); + spin_unlock_irqrestore(&wdt_spinlock, flags); +} + +static int wdt_startup(void) +{ + next_heartbeat = jiffies + (timeout * HZ); + + /* Start the timer */ + mod_timer(&timer, jiffies + WDT_INTERVAL); + + /* Start the watchdog */ + wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04); + + pr_info("Watchdog timer is now enabled\n"); + return 0; +} + +static int wdt_turnoff(void) +{ + /* Stop the timer */ + del_timer_sync(&timer); + + /* Stop the watchdog */ + wdt_config(0); + + pr_info("Watchdog timer is now disabled...\n"); + return 0; +} + +static int wdt_keepalive(void) +{ + /* user land ping */ + next_heartbeat = jiffies + (timeout * HZ); + return 0; +} + +static int wdt_set_heartbeat(int t) +{ + if ((t < 1) || (t > 3600)) /* arbitrary upper limit */ + return -EINVAL; + + timeout = t; + return 0; +} + +/* + * /dev/watchdog handling + */ + +static ssize_t fop_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + /* See if we got the magic character 'V' and reload the timer */ + if (count) { + if (!nowayout) { + size_t ofs; + + /* note: just in case someone wrote the magic character + * five months ago... */ + wdt_expect_close = 0; + + /* now scan */ + for (ofs = 0; ofs != count; ofs++) { + char c; + if (get_user(c, buf + ofs)) + return -EFAULT; + if (c == 'V') + wdt_expect_close = 42; + } + } + + /* Well, anyhow someone wrote to us, we should + return that favour */ + wdt_keepalive(); + } + return count; +} + +static int fop_open(struct inode *inode, struct file *file) +{ + /* Just in case we're already talking to someone... */ + if (test_and_set_bit(0, &wdt_is_open)) + return -EBUSY; + if (nowayout) + __module_get(THIS_MODULE); + + /* Good, fire up the show */ + wdt_startup(); + return stream_open(inode, file); +} + +static int fop_close(struct inode *inode, struct file *file) +{ + if (wdt_expect_close == 42) + wdt_turnoff(); + else { + pr_crit("Unexpected close, not stopping watchdog!\n"); + wdt_keepalive(); + } + clear_bit(0, &wdt_is_open); + wdt_expect_close = 0; + return 0; +} + +static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + void __user *argp = (void __user *)arg; + int __user *p = argp; + static const struct watchdog_info ident = { + .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT + | WDIOF_MAGICCLOSE, + .firmware_version = 1, + .identity = "SC520", + }; + + switch (cmd) { + case WDIOC_GETSUPPORT: + return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; + case WDIOC_GETSTATUS: + case WDIOC_GETBOOTSTATUS: + return put_user(0, p); + case WDIOC_SETOPTIONS: + { + int new_options, retval = -EINVAL; + + if (get_user(new_options, p)) + return -EFAULT; + + if (new_options & WDIOS_DISABLECARD) { + wdt_turnoff(); + retval = 0; + } + + if (new_options & WDIOS_ENABLECARD) { + wdt_startup(); + retval = 0; + } + + return retval; + } + case WDIOC_KEEPALIVE: + wdt_keepalive(); + return 0; + case WDIOC_SETTIMEOUT: + { + int new_timeout; + + if (get_user(new_timeout, p)) + return -EFAULT; + + if (wdt_set_heartbeat(new_timeout)) + return -EINVAL; + + wdt_keepalive(); + } + fallthrough; + case WDIOC_GETTIMEOUT: + return put_user(timeout, p); + default: + return -ENOTTY; + } +} + +static const struct file_operations wdt_fops = { + .owner = THIS_MODULE, + .llseek = no_llseek, + .write = fop_write, + .open = fop_open, + .release = fop_close, + .unlocked_ioctl = fop_ioctl, + .compat_ioctl = compat_ptr_ioctl, +}; + +static struct miscdevice wdt_miscdev = { + .minor = WATCHDOG_MINOR, + .name = "watchdog", + .fops = &wdt_fops, +}; + +/* + * Notifier for system down + */ + +static int wdt_notify_sys(struct notifier_block *this, unsigned long code, + void *unused) +{ + if (code == SYS_DOWN || code == SYS_HALT) + wdt_turnoff(); + return NOTIFY_DONE; +} + +/* + * The WDT needs to learn about soft shutdowns in order to + * turn the timebomb registers off. + */ + +static struct notifier_block wdt_notifier = { + .notifier_call = wdt_notify_sys, +}; + +static void __exit sc520_wdt_unload(void) +{ + if (!nowayout) + wdt_turnoff(); + + /* Deregister */ + misc_deregister(&wdt_miscdev); + unregister_reboot_notifier(&wdt_notifier); + iounmap(wdtmrctl); +} + +static int __init sc520_wdt_init(void) +{ + int rc = -EBUSY; + + /* Check that the timeout value is within it's range ; + if not reset to the default */ + if (wdt_set_heartbeat(timeout)) { + wdt_set_heartbeat(WATCHDOG_TIMEOUT); + pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n", + WATCHDOG_TIMEOUT); + } + + wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2); + if (!wdtmrctl) { + pr_err("Unable to remap memory\n"); + rc = -ENOMEM; + goto err_out_region2; + } + + rc = register_reboot_notifier(&wdt_notifier); + if (rc) { + pr_err("cannot register reboot notifier (err=%d)\n", rc); + goto err_out_ioremap; + } + + rc = misc_register(&wdt_miscdev); + if (rc) { + pr_err("cannot register miscdev on minor=%d (err=%d)\n", + WATCHDOG_MINOR, rc); + goto err_out_notifier; + } + + pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n", + timeout, nowayout); + + return 0; + +err_out_notifier: + unregister_reboot_notifier(&wdt_notifier); +err_out_ioremap: + iounmap(wdtmrctl); +err_out_region2: + return rc; +} + +module_init(sc520_wdt_init); +module_exit(sc520_wdt_unload); + +MODULE_AUTHOR("Scott and Bill Jennings"); +MODULE_DESCRIPTION( + "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor"); +MODULE_LICENSE("GPL"); |