text: /*
   * drivers/watchdog/ar7_wdt.c
   *
   * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org>
   * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
   *
   * Some code taken from:
   * National Semiconductor SCx200 Watchdog support
   * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/errno.h>
  #include <linux/init.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/notifier.h>
  #include <linux/reboot.h>
  #include <linux/fs.h>
  #include <linux/ioport.h>
  #include <linux/io.h>
  #include <linux/uaccess.h>
  
  #include <asm/addrspace.h>
  #include <asm/ar7/ar7.h>
  
  #define DRVNAME "ar7_wdt"
  #define LONGNAME "TI AR7 Watchdog Timer"
  
  MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  MODULE_DESCRIPTION(LONGNAME);
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  
  static int margin = 60;
  module_param(margin, int, 0);
  MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  
  static int nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, int, 0);
  MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  
  #define READ_REG(x) readl((void __iomem *)&(x))
  #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
  
  struct ar7_wdt {
  	u32 kick_lock;
  	u32 kick;
  	u32 change_lock;
  	u32 change;
  	u32 disable_lock;
  	u32 disable;
  	u32 prescale_lock;
  	u32 prescale;
  };
  
  static struct semaphore open_semaphore;
  static unsigned expect_close;
  
  /* XXX currently fixed, allows max margin ~68.72 secs */
  #define prescale_value 0xffff
  
  /* Offset of the WDT registers */
  static unsigned long ar7_regs_wdt;
  /* Pointer to the remapped WDT IO space */
  static struct ar7_wdt *ar7_wdt;
  static void ar7_wdt_get_regs(void)
  {
  	u16 chip_id = ar7_chip_id();
  	switch (chip_id) {
  	case AR7_CHIP_7100:
  	case AR7_CHIP_7200:
  		ar7_regs_wdt = AR7_REGS_WDT;
  		break;
  	default:
  		ar7_regs_wdt = UR8_REGS_WDT;
  		break;
  	}
  }
  
  
  static void ar7_wdt_kick(u32 value)
  {
  	WRITE_REG(ar7_wdt->kick_lock, 0x5555);
  	if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
  		WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
  		if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
  			WRITE_REG(ar7_wdt->kick, value);
  			return;
  		}
  	}
  	printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
  }
  
  static void ar7_wdt_prescale(u32 value)
  {
  	WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
  	if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
  		WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
  		if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
  			WRITE_REG(ar7_wdt->prescale, value);
  			return;
  		}
  	}
  	printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
  }
  
  static void ar7_wdt_change(u32 value)
  {
  	WRITE_REG(ar7_wdt->change_lock, 0x6666);
  	if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
  		WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
  		if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
  			WRITE_REG(ar7_wdt->change, value);
  			return;
  		}
  	}
  	printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
  }
  
  static void ar7_wdt_disable(u32 value)
  {
  	WRITE_REG(ar7_wdt->disable_lock, 0x7777);
  	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
  		WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
  		if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
  			WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
  			if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
  				WRITE_REG(ar7_wdt->disable, value);
  				return;
  			}
  		}
  	}
  	printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
  }
  
  static void ar7_wdt_update_margin(int new_margin)
  {
  	u32 change;
  
  	change = new_margin * (ar7_vbus_freq() / prescale_value);
  	if (change < 1) change = 1;
  	if (change > 0xffff) change = 0xffff;
  	ar7_wdt_change(change);
  	margin = change * prescale_value / ar7_vbus_freq();
  	printk(KERN_INFO DRVNAME
  	       ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
  	       margin, prescale_value, change, ar7_vbus_freq());
  }
  
  static void ar7_wdt_enable_wdt(void)
  {
  	printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
  	ar7_wdt_disable(1);
  	ar7_wdt_kick(1);
  }
  
  static void ar7_wdt_disable_wdt(void)
  {
  	printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
  	ar7_wdt_disable(0);
  }
  
  static int ar7_wdt_open(struct inode *inode, struct file *file)
  {
  	/* only allow one at a time */
  	if (down_trylock(&open_semaphore))
  		return -EBUSY;
  	ar7_wdt_enable_wdt();
  	expect_close = 0;
  
  	return nonseekable_open(inode, file);
  }
  
  static int ar7_wdt_release(struct inode *inode, struct file *file)
  {
  	if (!expect_close)
  		printk(KERN_WARNING DRVNAME
  		": watchdog device closed unexpectedly,"
  		"will not disable the watchdog timer\n");
  	else if (!nowayout)
  		ar7_wdt_disable_wdt();
  
  	up(&open_semaphore);
  
  	return 0;
  }
  
  static int ar7_wdt_notify_sys(struct notifier_block *this,
  			      unsigned long code, void *unused)
  {
  	if (code == SYS_HALT || code == SYS_POWER_OFF)
  		if (!nowayout)
  			ar7_wdt_disable_wdt();
  
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block ar7_wdt_notifier = {
  	.notifier_call = ar7_wdt_notify_sys
  };
  
  static ssize_t ar7_wdt_write(struct file *file, const char *data,
  			     size_t len, loff_t *ppos)
  {
  	/* check for a magic close character */
  	if (len) {
  		size_t i;
  
  		ar7_wdt_kick(1);
  
  		expect_close = 0;
  		for (i = 0; i < len; ++i) {
  			char c;
  			if (get_user(c, data+i))
  				return -EFAULT;
  			if (c == 'V')
  				expect_close = 1;
  		}
  
  	}
  	return len;
  }
  
  static int ar7_wdt_ioctl(struct inode *inode, struct file *file,
  			 unsigned int cmd, unsigned long arg)
  {
  	static struct watchdog_info ident = {
  		.identity = LONGNAME,
  		.firmware_version = 1,
  		.options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
  	};
  	int new_margin;
  
  	switch (cmd) {
  	default:
  		return -ENOTTY;
  	case WDIOC_GETSUPPORT:
  		if (copy_to_user((struct watchdog_info *)arg, &ident,
  				sizeof(ident)))
  			return -EFAULT;
  		return 0;
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		if (put_user(0, (int *)arg))
  			return -EFAULT;
  		return 0;
  	case WDIOC_KEEPALIVE:
  		ar7_wdt_kick(1);
  		return 0;
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_margin, (int *)arg))
  			return -EFAULT;
  		if (new_margin < 1)
  			return -EINVAL;
  
  		ar7_wdt_update_margin(new_margin);
  		ar7_wdt_kick(1);
  
  	case WDIOC_GETTIMEOUT:
  		if (put_user(margin, (int *)arg))
  			return -EFAULT;
  		return 0;
  	}
  }
  
  static struct file_operations ar7_wdt_fops = {
  	.owner		= THIS_MODULE,
  	.write		= ar7_wdt_write,
  	.ioctl		= ar7_wdt_ioctl,
  	.open		= ar7_wdt_open,
  	.release	= ar7_wdt_release,
  };
  
  static struct miscdevice ar7_wdt_miscdev = {
  	.minor		= WATCHDOG_MINOR,
  	.name		= "watchdog",
  	.fops		= &ar7_wdt_fops,
  };
  
  static int __init ar7_wdt_init(void)
  {
  	int rc;
  
  	ar7_wdt_get_regs();
  
  	if (!request_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt),
  							LONGNAME)) {
  		printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
  		return -EBUSY;
  	}
  
  	ar7_wdt = (struct ar7_wdt *)
  			ioremap(ar7_regs_wdt, sizeof(struct ar7_wdt));
  
  	ar7_wdt_disable_wdt();
  	ar7_wdt_prescale(prescale_value);
  	ar7_wdt_update_margin(margin);
  
  	sema_init(&open_semaphore, 1);
  
  	rc = register_reboot_notifier(&ar7_wdt_notifier);
  	if (rc) {
  		printk(KERN_ERR DRVNAME
  			": unable to register reboot notifier\n");
  		goto out_alloc;
  	}
  
  	rc = misc_register(&ar7_wdt_miscdev);
  	if (rc) {
  		printk(KERN_ERR DRVNAME ": unable to register misc device\n");
  		goto out_register;
  	}
  	goto out;
  
  out_register:
  	unregister_reboot_notifier(&ar7_wdt_notifier);
  out_alloc:
  	iounmap(ar7_wdt);
  	release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
  out:
  	return rc;
  }
  
  static void __exit ar7_wdt_cleanup(void)
  {
  	misc_deregister(&ar7_wdt_miscdev);
  	unregister_reboot_notifier(&ar7_wdt_notifier);
  	iounmap(ar7_wdt);
  	release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
  }
  
  module_init(ar7_wdt_init);
  module_exit(ar7_wdt_cleanup);
  