/*
   *	sch311x_wdt.c - Driver for the SCH311x Super-I/O chips
   *			integrated watchdog.
   *
   *	(c) Copyright 2008 Wim Van Sebroeck <wim@iguana.be>.
   *
   *	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.
   *
   *	Neither Wim Van Sebroeck nor Iguana vzw. admit liability nor
   *	provide warranty for any of this software. This material is
   *	provided "AS-IS" and at no charge.
   */
  
  /*
   *	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/... */
  #include <linux/miscdevice.h>		/* For struct miscdevice */
  #include <linux/watchdog.h>		/* For the watchdog specific items */
  #include <linux/init.h>			/* For __init/__exit/... */
  #include <linux/fs.h>			/* For file operations */
  #include <linux/platform_device.h>	/* For platform_driver framework */
  #include <linux/ioport.h>		/* For io-port access */
  #include <linux/spinlock.h>		/* For spin_lock/spin_unlock/... */
  #include <linux/uaccess.h>		/* For copy_to_user/put_user/... */
  #include <linux/io.h>			/* For inb/outb/... */
  
  /* Module and version information */
  #define DRV_NAME	"sch311x_wdt"
  
  /* Runtime registers */
  #define GP60			0x47
  #define WDT_TIME_OUT		0x65
  #define WDT_VAL			0x66
  #define WDT_CFG			0x67
  #define WDT_CTRL		0x68
  
  /* internal variables */
  static unsigned long sch311x_wdt_is_open;
  static char sch311x_wdt_expect_close;
  static struct platform_device *sch311x_wdt_pdev;
  
  static int sch311x_ioports[] = { 0x2e, 0x4e, 0x162e, 0x164e, 0x00 };
  
  static struct {	/* The devices private data */
  	/* the Runtime Register base address */
  	unsigned short runtime_reg;
  	/* The card's boot status */
  	int boot_status;
  	/* the lock for io operations */
  	spinlock_t io_lock;
  } sch311x_wdt_data;
  
  /* Module load parameters */
  static unsigned short force_id;
  module_param(force_id, ushort, 0);
  MODULE_PARM_DESC(force_id, "Override the detected device ID");
  
  #define WATCHDOG_TIMEOUT 60		/* 60 sec default timeout */
  static int timeout = WATCHDOG_TIMEOUT;	/* in seconds */
  module_param(timeout, int, 0);
  MODULE_PARM_DESC(timeout,
  	"Watchdog timeout in seconds. 1<= timeout <=15300, 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) ")");
  
  /*
   *	Super-IO functions
   */
  
  static inline void sch311x_sio_enter(int sio_config_port)
  {
  	outb(0x55, sio_config_port);
  }
  
  static inline void sch311x_sio_exit(int sio_config_port)
  {
  	outb(0xaa, sio_config_port);
  }
  
  static inline int sch311x_sio_inb(int sio_config_port, int reg)
  {
  	outb(reg, sio_config_port);
  	return inb(sio_config_port + 1);
  }
  
  static inline void sch311x_sio_outb(int sio_config_port, int reg, int val)
  {
  	outb(reg, sio_config_port);
  	outb(val, sio_config_port + 1);
  }
  
  /*
   *	Watchdog Operations
   */
  
  static void sch311x_wdt_set_timeout(int t)
  {
  	unsigned char timeout_unit = 0x80;
  
  	/* When new timeout is bigger then 255 seconds, we will use minutes */
  	if (t > 255) {
  		timeout_unit = 0;
  		t /= 60;
  	}
  
  	/* -- Watchdog Timeout --
  	 * Bit 0-6 (Reserved)
  	 * Bit 7   WDT Time-out Value Units Select
  	 *         (0 = Minutes, 1 = Seconds)
  	 */
  	outb(timeout_unit, sch311x_wdt_data.runtime_reg + WDT_TIME_OUT);
  
  	/* -- Watchdog Timer Time-out Value --
  	 * Bit 0-7 Binary coded units (0=Disabled, 1..255)
  	 */
  	outb(t, sch311x_wdt_data.runtime_reg + WDT_VAL);
  }
  
  static void sch311x_wdt_start(void)
  {
  	unsigned char t;
  
  	spin_lock(&sch311x_wdt_data.io_lock);
  
  	/* set watchdog's timeout */
  	sch311x_wdt_set_timeout(timeout);
  	/* enable the watchdog */
  	/* -- General Purpose I/O Bit 6.0 --
  	 * Bit 0,   In/Out: 0 = Output, 1 = Input
  	 * Bit 1,   Polarity: 0 = No Invert, 1 = Invert
  	 * Bit 2-3, Function select: 00 = GPI/O, 01 = LED1, 11 = WDT,
  	 *                           10 = Either Edge Triggered Intr.4
  	 * Bit 4-6  (Reserved)
  	 * Bit 7,   Output Type: 0 = Push Pull Bit, 1 = Open Drain
  	 */
  	t = inb(sch311x_wdt_data.runtime_reg + GP60);
  	outb((t & ~0x0d) | 0x0c, sch311x_wdt_data.runtime_reg + GP60);
  
  	spin_unlock(&sch311x_wdt_data.io_lock);
  
  }
  
  static void sch311x_wdt_stop(void)
  {
  	unsigned char t;
  
  	spin_lock(&sch311x_wdt_data.io_lock);
  
  	/* stop the watchdog */
  	t = inb(sch311x_wdt_data.runtime_reg + GP60);
  	outb((t & ~0x0d) | 0x01, sch311x_wdt_data.runtime_reg + GP60);
  	/* disable timeout by setting it to 0 */
  	sch311x_wdt_set_timeout(0);
  
  	spin_unlock(&sch311x_wdt_data.io_lock);
  }
  
  static void sch311x_wdt_keepalive(void)
  {
  	spin_lock(&sch311x_wdt_data.io_lock);
  	sch311x_wdt_set_timeout(timeout);
  	spin_unlock(&sch311x_wdt_data.io_lock);
  }
  
  static int sch311x_wdt_set_heartbeat(int t)
  {
  	if (t < 1 || t > (255*60))
  		return -EINVAL;
  
  	/* When new timeout is bigger then 255 seconds,
  	 * we will round up to minutes (with a max of 255) */
  	if (t > 255)
  		t = (((t - 1) / 60) + 1) * 60;
  
  	timeout = t;
  	return 0;
  }
  
  static void sch311x_wdt_get_status(int *status)
  {
  	unsigned char new_status;
  
  	*status = 0;
  
  	spin_lock(&sch311x_wdt_data.io_lock);
  
  	/* -- Watchdog timer control --
  	 * Bit 0   Status Bit: 0 = Timer counting, 1 = Timeout occurred
  	 * Bit 1   Reserved
  	 * Bit 2   Force Timeout: 1 = Forces WD timeout event (self-cleaning)
  	 * Bit 3   P20 Force Timeout enabled:
  	 *          0 = P20 activity does not generate the WD timeout event
  	 *          1 = P20 Allows rising edge of P20, from the keyboard
  	 *              controller, to force the WD timeout event.
  	 * Bit 4-7 Reserved
  	 */
  	new_status = inb(sch311x_wdt_data.runtime_reg + WDT_CTRL);
  	if (new_status & 0x01)
  		*status |= WDIOF_CARDRESET;
  
  	spin_unlock(&sch311x_wdt_data.io_lock);
  }
  
  /*
   *	/dev/watchdog handling
   */
  
  static ssize_t sch311x_wdt_write(struct file *file, const char __user *buf,
  						size_t count, loff_t *ppos)
  {
  	if (count) {
  		if (!nowayout) {
  			size_t i;
  
  			sch311x_wdt_expect_close = 0;
  
  			for (i = 0; i != count; i++) {
  				char c;
  				if (get_user(c, buf + i))
  					return -EFAULT;
  				if (c == 'V')
  					sch311x_wdt_expect_close = 42;
  			}
  		}
  		sch311x_wdt_keepalive();
  	}
  	return count;
  }
  
  static long sch311x_wdt_ioctl(struct file *file, unsigned int cmd,
  							unsigned long arg)
  {
  	int status;
  	int new_timeout;
  	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		= DRV_NAME,
  	};
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		if (copy_to_user(argp, &ident, sizeof(ident)))
  			return -EFAULT;
  		break;
  
  	case WDIOC_GETSTATUS:
  	{
  		sch311x_wdt_get_status(&status);
  		return put_user(status, p);
  	}
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(sch311x_wdt_data.boot_status, p);
  
  	case WDIOC_SETOPTIONS:
  	{
  		int options, retval = -EINVAL;
  
  		if (get_user(options, p))
  			return -EFAULT;
  		if (options & WDIOS_DISABLECARD) {
  			sch311x_wdt_stop();
  			retval = 0;
  		}
  		if (options & WDIOS_ENABLECARD) {
  			sch311x_wdt_start();
  			retval = 0;
  		}
  		return retval;
  	}
  	case WDIOC_KEEPALIVE:
  		sch311x_wdt_keepalive();
  		break;
  
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_timeout, p))
  			return -EFAULT;
  		if (sch311x_wdt_set_heartbeat(new_timeout))
  			return -EINVAL;
  		sch311x_wdt_keepalive();
  		/* Fall */
  	case WDIOC_GETTIMEOUT:
  		return put_user(timeout, p);
  	default:
  		return -ENOTTY;
  	}
  	return 0;
  }
  
  static int sch311x_wdt_open(struct inode *inode, struct file *file)
  {
  	if (test_and_set_bit(0, &sch311x_wdt_is_open))
  		return -EBUSY;
  	/*
  	 *	Activate
  	 */
  	sch311x_wdt_start();
  	return nonseekable_open(inode, file);
  }
  
  static int sch311x_wdt_close(struct inode *inode, struct file *file)
  {
  	if (sch311x_wdt_expect_close == 42) {
  		sch311x_wdt_stop();
  	} else {
  		pr_crit("Unexpected close, not stopping watchdog!
  ");
  		sch311x_wdt_keepalive();
  	}
  	clear_bit(0, &sch311x_wdt_is_open);
  	sch311x_wdt_expect_close = 0;
  	return 0;
  }
  
  /*
   *	Kernel Interfaces
   */
  
  static const struct file_operations sch311x_wdt_fops = {
  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= sch311x_wdt_write,
  	.unlocked_ioctl	= sch311x_wdt_ioctl,
  	.open		= sch311x_wdt_open,
  	.release	= sch311x_wdt_close,
  };
  
  static struct miscdevice sch311x_wdt_miscdev = {
  	.minor	= WATCHDOG_MINOR,
  	.name	= "watchdog",
  	.fops	= &sch311x_wdt_fops,
  };
  
  /*
   *	Init & exit routines
   */
  
  static int sch311x_wdt_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	int err;
  
  	spin_lock_init(&sch311x_wdt_data.io_lock);
  
  	if (!request_region(sch311x_wdt_data.runtime_reg + GP60, 1, DRV_NAME)) {
  		dev_err(dev, "Failed to request region 0x%04x-0x%04x.
  ",
  			sch311x_wdt_data.runtime_reg + GP60,
  			sch311x_wdt_data.runtime_reg + GP60);
  		err = -EBUSY;
  		goto exit;
  	}
  
  	if (!request_region(sch311x_wdt_data.runtime_reg + WDT_TIME_OUT, 4,
  								DRV_NAME)) {
  		dev_err(dev, "Failed to request region 0x%04x-0x%04x.
  ",
  			sch311x_wdt_data.runtime_reg + WDT_TIME_OUT,
  			sch311x_wdt_data.runtime_reg + WDT_CTRL);
  		err = -EBUSY;
  		goto exit_release_region;
  	}
  
  	/* Make sure that the watchdog is not running */
  	sch311x_wdt_stop();
  
  	/* Disable keyboard and mouse interaction and interrupt */
  	/* -- Watchdog timer configuration --
  	 * Bit 0   Reserved
  	 * Bit 1   Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr.
  	 * Bit 2   Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr
  	 * Bit 3   Reserved
  	 * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled,
  	 *            0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15)
  	 */
  	outb(0, sch311x_wdt_data.runtime_reg + WDT_CFG);
  
  	/* Check that the heartbeat value is within it's range ;
  	 * if not reset to the default */
  	if (sch311x_wdt_set_heartbeat(timeout)) {
  		sch311x_wdt_set_heartbeat(WATCHDOG_TIMEOUT);
  		dev_info(dev, "timeout value must be 1<=x<=15300, using %d
  ",
  			timeout);
  	}
  
  	/* Get status at boot */
  	sch311x_wdt_get_status(&sch311x_wdt_data.boot_status);
  
  	sch311x_wdt_miscdev.parent = dev;
  
  	err = misc_register(&sch311x_wdt_miscdev);
  	if (err != 0) {
  		dev_err(dev, "cannot register miscdev on minor=%d (err=%d)
  ",
  							WATCHDOG_MINOR, err);
  		goto exit_release_region2;
  	}
  
  	dev_info(dev,
  		"SMSC SCH311x WDT initialized. timeout=%d sec (nowayout=%d)
  ",
  		timeout, nowayout);
  
  	return 0;
  
  exit_release_region2:
  	release_region(sch311x_wdt_data.runtime_reg + WDT_TIME_OUT, 4);
  exit_release_region:
  	release_region(sch311x_wdt_data.runtime_reg + GP60, 1);
  	sch311x_wdt_data.runtime_reg = 0;
  exit:
  	return err;
  }
  
  static int sch311x_wdt_remove(struct platform_device *pdev)
  {
  	/* Stop the timer before we leave */
  	if (!nowayout)
  		sch311x_wdt_stop();
  
  	/* Deregister */
  	misc_deregister(&sch311x_wdt_miscdev);
  	release_region(sch311x_wdt_data.runtime_reg + WDT_TIME_OUT, 4);
  	release_region(sch311x_wdt_data.runtime_reg + GP60, 1);
  	sch311x_wdt_data.runtime_reg = 0;
  	return 0;
  }
  
  static void sch311x_wdt_shutdown(struct platform_device *dev)
  {
  	/* Turn the WDT off if we have a soft shutdown */
  	sch311x_wdt_stop();
  }
  
  static struct platform_driver sch311x_wdt_driver = {
  	.probe		= sch311x_wdt_probe,
  	.remove		= sch311x_wdt_remove,
  	.shutdown	= sch311x_wdt_shutdown,
  	.driver		= {
  		.owner = THIS_MODULE,
  		.name = DRV_NAME,
  	},
  };
  
  static int __init sch311x_detect(int sio_config_port, unsigned short *addr)
  {
  	int err = 0, reg;
  	unsigned short base_addr;
  	unsigned char dev_id;
  
  	sch311x_sio_enter(sio_config_port);
  
  	/* Check device ID. We currently know about:
  	 * SCH3112 (0x7c), SCH3114 (0x7d), and SCH3116 (0x7f). */
  	reg = force_id ? force_id : sch311x_sio_inb(sio_config_port, 0x20);
  	if (!(reg == 0x7c || reg == 0x7d || reg == 0x7f)) {
  		err = -ENODEV;
  		goto exit;
  	}
  	dev_id = reg == 0x7c ? 2 : reg == 0x7d ? 4 : 6;
  
  	/* Select logical device A (runtime registers) */
  	sch311x_sio_outb(sio_config_port, 0x07, 0x0a);
  
  	/* Check if Logical Device Register is currently active */
  	if ((sch311x_sio_inb(sio_config_port, 0x30) & 0x01) == 0)
  		pr_info("Seems that LDN 0x0a is not active...
  ");
  
  	/* Get the base address of the runtime registers */
  	base_addr = (sch311x_sio_inb(sio_config_port, 0x60) << 8) |
  			   sch311x_sio_inb(sio_config_port, 0x61);
  	if (!base_addr) {
  		pr_err("Base address not set
  ");
  		err = -ENODEV;
  		goto exit;
  	}
  	*addr = base_addr;
  
  	pr_info("Found an SMSC SCH311%d chip at 0x%04x
  ", dev_id, base_addr);
  
  exit:
  	sch311x_sio_exit(sio_config_port);
  	return err;
  }
  
  static int __init sch311x_wdt_init(void)
  {
  	int err, i, found = 0;
  	unsigned short addr = 0;
  
  	for (i = 0; !found && sch311x_ioports[i]; i++)
  		if (sch311x_detect(sch311x_ioports[i], &addr) == 0)
  			found++;
  
  	if (!found)
  		return -ENODEV;
  
  	sch311x_wdt_data.runtime_reg = addr;
  
  	err = platform_driver_register(&sch311x_wdt_driver);
  	if (err)
  		return err;
  
  	sch311x_wdt_pdev = platform_device_register_simple(DRV_NAME, addr,
  								NULL, 0);
  
  	if (IS_ERR(sch311x_wdt_pdev)) {
  		err = PTR_ERR(sch311x_wdt_pdev);
  		goto unreg_platform_driver;
  	}
  
  	return 0;
  
  unreg_platform_driver:
  	platform_driver_unregister(&sch311x_wdt_driver);
  	return err;
  }
  
  static void __exit sch311x_wdt_exit(void)
  {
  	platform_device_unregister(sch311x_wdt_pdev);
  	platform_driver_unregister(&sch311x_wdt_driver);
  }
  
  module_init(sch311x_wdt_init);
  module_exit(sch311x_wdt_exit);
  
  MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
  MODULE_DESCRIPTION("SMSC SCH311x WatchDog Timer Driver");
  MODULE_LICENSE("GPL");