diff options
Diffstat (limited to 'drivers/watchdog/acquirewdt.c')
| -rw-r--r-- | drivers/watchdog/acquirewdt.c | 331 |
1 files changed, 331 insertions, 0 deletions
diff --git a/drivers/watchdog/acquirewdt.c b/drivers/watchdog/acquirewdt.c new file mode 100644 index 000000000..bc6f33356 --- /dev/null +++ b/drivers/watchdog/acquirewdt.c @@ -0,0 +1,331 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Acquire Single Board Computer Watchdog Timer driver + * + * Based on wdt.c. Original copyright messages: + * + * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, + * All Rights Reserved. + * + * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide + * warranty for any of this software. This material is provided + * "AS-IS" and at no charge. + * + * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk> + * + * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> + * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT + * Can't add timeout - driver doesn't allow changing value + */ + +/* + * Theory of Operation: + * The Watch-Dog Timer is provided to ensure that standalone + * Systems can always recover from catastrophic conditions that + * caused the CPU to crash. This condition may have occurred by + * external EMI or a software bug. When the CPU stops working + * correctly, hardware on the board will either perform a hardware + * reset (cold boot) or a non-maskable interrupt (NMI) to bring the + * system back to a known state. + * + * The Watch-Dog Timer is controlled by two I/O Ports. + * 443 hex - Read - Enable or refresh the Watch-Dog Timer + * 043 hex - Read - Disable the Watch-Dog Timer + * + * To enable the Watch-Dog Timer, a read from I/O port 443h must + * be performed. This will enable and activate the countdown timer + * which will eventually time out and either reset the CPU or cause + * an NMI depending on the setting of a jumper. To ensure that this + * reset condition does not occur, the Watch-Dog Timer must be + * periodically refreshed by reading the same I/O port 443h. + * The Watch-Dog Timer is disabled by reading I/O port 043h. + * + * The Watch-Dog Timer Time-Out Period is set via jumpers. + * It can be 1, 2, 10, 20, 110 or 220 seconds. + */ + +/* + * Includes, defines, variables, module parameters, ... + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +/* Includes */ +#include <linux/module.h> /* For module specific items */ +#include <linux/moduleparam.h> /* For new moduleparam's */ +#include <linux/types.h> /* For standard types (like size_t) */ +#include <linux/errno.h> /* For the -ENODEV/... values */ +#include <linux/kernel.h> /* For printk/panic/... */ +#include <linux/miscdevice.h> /* For struct miscdevice */ +#include <linux/watchdog.h> /* For the watchdog specific items */ +#include <linux/fs.h> /* For file operations */ +#include <linux/ioport.h> /* For io-port access */ +#include <linux/platform_device.h> /* For platform_driver framework */ +#include <linux/init.h> /* For __init/__exit/... */ +#include <linux/uaccess.h> /* For copy_to_user/put_user/... */ +#include <linux/io.h> /* For inb/outb/... */ + +/* Module information */ +#define DRV_NAME "acquirewdt" +#define WATCHDOG_NAME "Acquire WDT" +/* There is no way to see what the correct time-out period is */ +#define WATCHDOG_HEARTBEAT 0 + +/* internal variables */ +/* the watchdog platform device */ +static struct platform_device *acq_platform_device; +static unsigned long acq_is_open; +static char expect_close; + +/* module parameters */ +/* You must set this - there is no sane way to probe for this board. */ +static int wdt_stop = 0x43; +module_param(wdt_stop, int, 0); +MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)"); + +/* You must set this - there is no sane way to probe for this board. */ +static int wdt_start = 0x443; +module_param(wdt_start, int, 0); +MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)"); + +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) ")"); + +/* + * Watchdog Operations + */ + +static void acq_keepalive(void) +{ + /* Write a watchdog value */ + inb_p(wdt_start); +} + +static void acq_stop(void) +{ + /* Turn the card off */ + inb_p(wdt_stop); +} + +/* + * /dev/watchdog handling + */ + +static ssize_t acq_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 i; + /* note: just in case someone wrote the magic character + five months ago... */ + expect_close = 0; + /* scan to see whether or not we got the + magic character */ + for (i = 0; i != count; i++) { + char c; + if (get_user(c, buf + i)) + return -EFAULT; + if (c == 'V') + expect_close = 42; + } + } + /* Well, anyhow someone wrote to us, we should + return that favour */ + acq_keepalive(); + } + return count; +} + +static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + int options, retval = -EINVAL; + void __user *argp = (void __user *)arg; + int __user *p = argp; + static const struct watchdog_info ident = { + .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, + .firmware_version = 1, + .identity = WATCHDOG_NAME, + }; + + 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: + { + if (get_user(options, p)) + return -EFAULT; + if (options & WDIOS_DISABLECARD) { + acq_stop(); + retval = 0; + } + if (options & WDIOS_ENABLECARD) { + acq_keepalive(); + retval = 0; + } + return retval; + } + case WDIOC_KEEPALIVE: + acq_keepalive(); + return 0; + + case WDIOC_GETTIMEOUT: + return put_user(WATCHDOG_HEARTBEAT, p); + + default: + return -ENOTTY; + } +} + +static int acq_open(struct inode *inode, struct file *file) +{ + if (test_and_set_bit(0, &acq_is_open)) + return -EBUSY; + + if (nowayout) + __module_get(THIS_MODULE); + + /* Activate */ + acq_keepalive(); + return stream_open(inode, file); +} + +static int acq_close(struct inode *inode, struct file *file) +{ + if (expect_close == 42) { + acq_stop(); + } else { + pr_crit("Unexpected close, not stopping watchdog!\n"); + acq_keepalive(); + } + clear_bit(0, &acq_is_open); + expect_close = 0; + return 0; +} + +/* + * Kernel Interfaces + */ + +static const struct file_operations acq_fops = { + .owner = THIS_MODULE, + .llseek = no_llseek, + .write = acq_write, + .unlocked_ioctl = acq_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .open = acq_open, + .release = acq_close, +}; + +static struct miscdevice acq_miscdev = { + .minor = WATCHDOG_MINOR, + .name = "watchdog", + .fops = &acq_fops, +}; + +/* + * Init & exit routines + */ + +static int __init acq_probe(struct platform_device *dev) +{ + int ret; + + if (wdt_stop != wdt_start) { + if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) { + pr_err("I/O address 0x%04x already in use\n", wdt_stop); + ret = -EIO; + goto out; + } + } + + if (!request_region(wdt_start, 1, WATCHDOG_NAME)) { + pr_err("I/O address 0x%04x already in use\n", wdt_start); + ret = -EIO; + goto unreg_stop; + } + ret = misc_register(&acq_miscdev); + if (ret != 0) { + pr_err("cannot register miscdev on minor=%d (err=%d)\n", + WATCHDOG_MINOR, ret); + goto unreg_regions; + } + pr_info("initialized. (nowayout=%d)\n", nowayout); + + return 0; +unreg_regions: + release_region(wdt_start, 1); +unreg_stop: + if (wdt_stop != wdt_start) + release_region(wdt_stop, 1); +out: + return ret; +} + +static int acq_remove(struct platform_device *dev) +{ + misc_deregister(&acq_miscdev); + release_region(wdt_start, 1); + if (wdt_stop != wdt_start) + release_region(wdt_stop, 1); + + return 0; +} + +static void acq_shutdown(struct platform_device *dev) +{ + /* Turn the WDT off if we have a soft shutdown */ + acq_stop(); +} + +static struct platform_driver acquirewdt_driver = { + .remove = acq_remove, + .shutdown = acq_shutdown, + .driver = { + .name = DRV_NAME, + }, +}; + +static int __init acq_init(void) +{ + int err; + + pr_info("WDT driver for Acquire single board computer initialising\n"); + + acq_platform_device = platform_device_register_simple(DRV_NAME, + -1, NULL, 0); + if (IS_ERR(acq_platform_device)) + return PTR_ERR(acq_platform_device); + + err = platform_driver_probe(&acquirewdt_driver, acq_probe); + if (err) + goto unreg_platform_device; + return 0; + +unreg_platform_device: + platform_device_unregister(acq_platform_device); + return err; +} + +static void __exit acq_exit(void) +{ + platform_device_unregister(acq_platform_device); + platform_driver_unregister(&acquirewdt_driver); + pr_info("Watchdog Module Unloaded\n"); +} + +module_init(acq_init); +module_exit(acq_exit); + +MODULE_AUTHOR("David Woodhouse"); +MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver"); +MODULE_LICENSE("GPL"); |