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* Watchdog driver for SBC-FITPC2 board
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* Author: Denis Turischev <denis@compulab.co.il>
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* Adapted from the IXP2000 watchdog driver by Deepak Saxena.
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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#define pr_fmt(fmt) KBUILD_MODNAME " WATCHDOG: " fmt
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/ioport.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/moduleparam.h>
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#include <linux/dmi.h>
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#include <linux/uaccess.h>
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#include <asm/system.h>
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static int nowayout = WATCHDOG_NOWAYOUT;
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static unsigned int margin = 60; /* (secs) Default is 1 minute */
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static unsigned long wdt_status;
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static DEFINE_MUTEX(wdt_lock);
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#define WDT_OK_TO_CLOSE 1
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#define COMMAND_PORT 0x4c
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#define DATA_PORT 0x48
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#define IFACE_ON_COMMAND 1
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#define REBOOT_COMMAND 2
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#define WATCHDOG_NAME "SBC-FITPC2 Watchdog"
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static void wdt_send_data(unsigned char command, unsigned char data)
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outb(data, DATA_PORT);
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outb(command, COMMAND_PORT);
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static void wdt_enable(void)
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mutex_lock(&wdt_lock);
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wdt_send_data(IFACE_ON_COMMAND, 1);
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wdt_send_data(REBOOT_COMMAND, margin);
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mutex_unlock(&wdt_lock);
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static void wdt_disable(void)
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mutex_lock(&wdt_lock);
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wdt_send_data(IFACE_ON_COMMAND, 0);
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wdt_send_data(REBOOT_COMMAND, 0);
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mutex_unlock(&wdt_lock);
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static int fitpc2_wdt_open(struct inode *inode, struct file *file)
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if (test_and_set_bit(WDT_IN_USE, &wdt_status))
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clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
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return nonseekable_open(inode, file);
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static ssize_t fitpc2_wdt_write(struct file *file, const char *data,
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size_t len, loff_t *ppos)
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clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
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for (i = 0; i != len; i++) {
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if (get_user(c, data + i))
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set_bit(WDT_OK_TO_CLOSE, &wdt_status);
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static const struct watchdog_info ident = {
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.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
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.identity = WATCHDOG_NAME,
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static long fitpc2_wdt_ioctl(struct file *file, unsigned int cmd,
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case WDIOC_GETSUPPORT:
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ret = copy_to_user((struct watchdog_info *)arg, &ident,
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sizeof(ident)) ? -EFAULT : 0;
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case WDIOC_GETSTATUS:
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ret = put_user(0, (int *)arg);
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case WDIOC_GETBOOTSTATUS:
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ret = put_user(0, (int *)arg);
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case WDIOC_KEEPALIVE:
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case WDIOC_SETTIMEOUT:
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ret = get_user(time, (int *)arg);
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if (time < 31 || time > 255) {
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case WDIOC_GETTIMEOUT:
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ret = put_user(margin, (int *)arg);
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static int fitpc2_wdt_release(struct inode *inode, struct file *file)
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if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
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pr_info("Device disabled\n");
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pr_warning("Device closed unexpectedly -"
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" timer will not stop\n");
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clear_bit(WDT_IN_USE, &wdt_status);
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clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
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static const struct file_operations fitpc2_wdt_fops = {
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.owner = THIS_MODULE,
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.write = fitpc2_wdt_write,
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.unlocked_ioctl = fitpc2_wdt_ioctl,
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.open = fitpc2_wdt_open,
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.release = fitpc2_wdt_release,
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static struct miscdevice fitpc2_wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.fops = &fitpc2_wdt_fops,
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static int __init fitpc2_wdt_init(void)
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const char *brd_name;
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brd_name = dmi_get_system_info(DMI_BOARD_NAME);
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if (!brd_name || !strstr(brd_name, "SBC-FITPC2"))
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pr_info("%s found\n", brd_name);
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if (!request_region(COMMAND_PORT, 1, WATCHDOG_NAME)) {
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pr_err("I/O address 0x%04x already in use\n", COMMAND_PORT);
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if (!request_region(DATA_PORT, 1, WATCHDOG_NAME)) {
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pr_err("I/O address 0x%04x already in use\n", DATA_PORT);
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if (margin < 31 || margin > 255) {
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pr_err("margin must be in range 31 - 255"
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" seconds, you tried to set %d\n", margin);
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err = misc_register(&fitpc2_wdt_miscdev);
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pr_err("cannot register miscdev on minor=%d (err=%d)\n",
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WATCHDOG_MINOR, err);
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release_region(DATA_PORT, 1);
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release_region(COMMAND_PORT, 1);
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static void __exit fitpc2_wdt_exit(void)
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misc_deregister(&fitpc2_wdt_miscdev);
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release_region(DATA_PORT, 1);
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release_region(COMMAND_PORT, 1);
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module_init(fitpc2_wdt_init);
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module_exit(fitpc2_wdt_exit);
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MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
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MODULE_DESCRIPTION("SBC-FITPC2 Watchdog");
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module_param(margin, int, 0);
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MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
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module_param(nowayout, int, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);