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/*
 * IBM Automatic Server Restart driver.
 *
 * Copyright (c) 2005 Andrey Panin <pazke@donpac.ru>
 *
 * Based on driver written by Pete Reynolds.
 * Copyright (c) IBM Corporation, 1998-2004.
 *
 * This software may be used and distributed according to the terms
 * of the GNU Public License, incorporated herein by reference.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/dmi.h>
#include <linux/io.h>
#include <linux/uaccess.h>


enum {
	ASMTYPE_UNKNOWN,
	ASMTYPE_TOPAZ,
	ASMTYPE_JASPER,
	ASMTYPE_PEARL,
	ASMTYPE_JUNIPER,
	ASMTYPE_SPRUCE,
};

#define TOPAZ_ASR_REG_OFFSET	4
#define TOPAZ_ASR_TOGGLE	0x40
#define TOPAZ_ASR_DISABLE	0x80

/* PEARL ASR S/W REGISTER SUPERIO PORT ADDRESSES */
#define PEARL_BASE	0xe04
#define PEARL_WRITE	0xe06
#define PEARL_READ	0xe07

#define PEARL_ASR_DISABLE_MASK	0x80	/* bit 7: disable = 1, enable = 0 */
#define PEARL_ASR_TOGGLE_MASK	0x40	/* bit 6: 0, then 1, then 0 */

/* JASPER OFFSET FROM SIO BASE ADDR TO ASR S/W REGISTERS. */
#define JASPER_ASR_REG_OFFSET	0x38

#define JASPER_ASR_DISABLE_MASK	0x01	/* bit 0: disable = 1, enable = 0 */
#define JASPER_ASR_TOGGLE_MASK	0x02	/* bit 1: 0, then 1, then 0 */

#define JUNIPER_BASE_ADDRESS	0x54b	/* Base address of Juniper ASR */
#define JUNIPER_ASR_DISABLE_MASK 0x01	/* bit 0: disable = 1 enable = 0 */
#define JUNIPER_ASR_TOGGLE_MASK	0x02	/* bit 1: 0, then 1, then 0 */

#define SPRUCE_BASE_ADDRESS	0x118e	/* Base address of Spruce ASR */
#define SPRUCE_ASR_DISABLE_MASK	0x01	/* bit 1: disable = 1 enable = 0 */
#define SPRUCE_ASR_TOGGLE_MASK	0x02	/* bit 0: 0, then 1, then 0 */


static bool nowayout = WATCHDOG_NOWAYOUT;

static unsigned long asr_is_open;
static char asr_expect_close;

static unsigned int asr_type, asr_base, asr_length;
static unsigned int asr_read_addr, asr_write_addr;
static unsigned char asr_toggle_mask, asr_disable_mask;
static DEFINE_SPINLOCK(asr_lock);

static void __asr_toggle(void)
{
	unsigned char reg;

	reg = inb(asr_read_addr);

	outb(reg & ~asr_toggle_mask, asr_write_addr);
	reg = inb(asr_read_addr);

	outb(reg | asr_toggle_mask, asr_write_addr);
	reg = inb(asr_read_addr);

	outb(reg & ~asr_toggle_mask, asr_write_addr);
	reg = inb(asr_read_addr);
}

static void asr_toggle(void)
{
	spin_lock(&asr_lock);
	__asr_toggle();
	spin_unlock(&asr_lock);
}

static void asr_enable(void)
{
	unsigned char reg;

	spin_lock(&asr_lock);
	if (asr_type == ASMTYPE_TOPAZ) {
		/* asr_write_addr == asr_read_addr */
		reg = inb(asr_read_addr);
		outb(reg & ~(TOPAZ_ASR_TOGGLE | TOPAZ_ASR_DISABLE),
		     asr_read_addr);
	} else {
		/*
		 * First make sure the hardware timer is reset by toggling
		 * ASR hardware timer line.
		 */
		__asr_toggle();

		reg = inb(asr_read_addr);
		outb(reg & ~asr_disable_mask, asr_write_addr);
	}
	reg = inb(asr_read_addr);
	spin_unlock(&asr_lock);
}

static void asr_disable(void)
{
	unsigned char reg;

	spin_lock(&asr_lock);
	reg = inb(asr_read_addr);

	if (asr_type == ASMTYPE_TOPAZ)
		/* asr_write_addr == asr_read_addr */
		outb(reg | TOPAZ_ASR_TOGGLE | TOPAZ_ASR_DISABLE,
		     asr_read_addr);
	else {
		outb(reg | asr_toggle_mask, asr_write_addr);
		reg = inb(asr_read_addr);

		outb(reg | asr_disable_mask, asr_write_addr);
	}
	reg = inb(asr_read_addr);
	spin_unlock(&asr_lock);
}

static int __init asr_get_base_address(void)
{
	unsigned char low, high;
	const char *type = "";

	asr_length = 1;

	switch (asr_type) {
	case ASMTYPE_TOPAZ:
		/* SELECT SuperIO CHIP FOR QUERYING
		   (WRITE 0x07 TO BOTH 0x2E and 0x2F) */
		outb(0x07, 0x2e);
		outb(0x07, 0x2f);

		/* SELECT AND READ THE HIGH-NIBBLE OF THE GPIO BASE ADDRESS */
		outb(0x60, 0x2e);
		high = inb(0x2f);

		/* SELECT AND READ THE LOW-NIBBLE OF THE GPIO BASE ADDRESS */
		outb(0x61, 0x2e);
		low = inb(0x2f);

		asr_base = (high << 16) | low;
		asr_read_addr = asr_write_addr =
			asr_base + TOPAZ_ASR_REG_OFFSET;
		asr_length = 5;

		break;

	case ASMTYPE_JASPER:
		type = "Jaspers ";
#if 0
		u32 r;
		/* Suggested fix */
		pdev = pci_get_bus_and_slot(0, DEVFN(0x1f, 0));
		if (pdev == NULL)
			return -ENODEV;
		pci_read_config_dword(pdev, 0x58, &r);
		asr_base = r & 0xFFFE;
		pci_dev_put(pdev);
#else
		/* FIXME: need to use pci_config_lock here,
		   but it's not exported */

/*		spin_lock_irqsave(&pci_config_lock, flags);*/

		/* Select the SuperIO chip in the PCI I/O port register */
		outl(0x8000f858, 0xcf8);

		/* BUS 0, Slot 1F, fnc 0, offset 58 */

		/*
		 * Read the base address for the SuperIO chip.
		 * Only the lower 16 bits are valid, but the address is word
		 * aligned so the last bit must be masked off.
		 */
		asr_base = inl(0xcfc) & 0xfffe;

/*		spin_unlock_irqrestore(&pci_config_lock, flags);*/
#endif
		asr_read_addr = asr_write_addr =
			asr_base + JASPER_ASR_REG_OFFSET;
		asr_toggle_mask = JASPER_ASR_TOGGLE_MASK;
		asr_disable_mask = JASPER_ASR_DISABLE_MASK;
		asr_length = JASPER_ASR_REG_OFFSET + 1;

		break;

	case ASMTYPE_PEARL:
		type = "Pearls ";
		asr_base = PEARL_BASE;
		asr_read_addr = PEARL_READ;
		asr_write_addr = PEARL_WRITE;
		asr_toggle_mask = PEARL_ASR_TOGGLE_MASK;
		asr_disable_mask = PEARL_ASR_DISABLE_MASK;
		asr_length = 4;
		break;

	case ASMTYPE_JUNIPER:
		type = "Junipers ";
		asr_base = JUNIPER_BASE_ADDRESS;
		asr_read_addr = asr_write_addr = asr_base;
		asr_toggle_mask = JUNIPER_ASR_TOGGLE_MASK;
		asr_disable_mask = JUNIPER_ASR_DISABLE_MASK;
		break;

	case ASMTYPE_SPRUCE:
		type = "Spruce's ";
		asr_base = SPRUCE_BASE_ADDRESS;
		asr_read_addr = asr_write_addr = asr_base;
		asr_toggle_mask = SPRUCE_ASR_TOGGLE_MASK;
		asr_disable_mask = SPRUCE_ASR_DISABLE_MASK;
		break;
	}

	if (!request_region(asr_base, asr_length, "ibmasr")) {
		pr_err("address %#x already in use\n", asr_base);
		return -EBUSY;
	}

	pr_info("found %sASR @ addr %#x\n", type, asr_base);

	return 0;
}


static ssize_t asr_write(struct file *file, const char __user *buf,
			 size_t count, loff_t *ppos)
{
	if (count) {
		if (!nowayout) {
			size_t i;

			/* In case it was set long ago */
			asr_expect_close = 0;

			for (i = 0; i != count; i++) {
				char c;
				if (get_user(c, buf + i))
					return -EFAULT;
				if (c == 'V')
					asr_expect_close = 42;
			}
		}
		asr_toggle();
	}
	return count;
}

static long asr_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	static const struct watchdog_info ident = {
		.options =	WDIOF_KEEPALIVEPING |
				WDIOF_MAGICCLOSE,
		.identity =	"IBM ASR",
	};
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	int heartbeat;

	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) {
			asr_disable();
			retval = 0;
		}
		if (new_options & WDIOS_ENABLECARD) {
			asr_enable();
			asr_toggle();
			retval = 0;
		}
		return retval;
	}
	case WDIOC_KEEPALIVE:
		asr_toggle();
		return 0;
	/*
	 * The hardware has a fixed timeout value, so no WDIOC_SETTIMEOUT
	 * and WDIOC_GETTIMEOUT always returns 256.
	 */
	case WDIOC_GETTIMEOUT:
		heartbeat = 256;
		return put_user(heartbeat, p);
	default:
		return -ENOTTY;
	}
}

static int asr_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(0, &asr_is_open))
		return -EBUSY;

	asr_toggle();
	asr_enable();

	return nonseekable_open(inode, file);
}

static int asr_release(struct inode *inode, struct file *file)
{
	if (asr_expect_close == 42)
		asr_disable();
	else {
		pr_crit("unexpected close, not stopping watchdog!\n");
		asr_toggle();
	}
	clear_bit(0, &asr_is_open);
	asr_expect_close = 0;
	return 0;
}

static const struct file_operations asr_fops = {
	.owner =		THIS_MODULE,
	.llseek =		no_llseek,
	.write =		asr_write,
	.unlocked_ioctl =	asr_ioctl,
	.open =			asr_open,
	.release =		asr_release,
};

static struct miscdevice asr_miscdev = {
	.minor =	WATCHDOG_MINOR,
	.name =		"watchdog",
	.fops =		&asr_fops,
};


struct ibmasr_id {
	const char *desc;
	int type;
};

static struct ibmasr_id ibmasr_id_table[] __initdata = {
	{ "IBM Automatic Server Restart - eserver xSeries 220", ASMTYPE_TOPAZ },
	{ "IBM Automatic Server Restart - Machine Type 8673", ASMTYPE_PEARL },
	{ "IBM Automatic Server Restart - Machine Type 8480", ASMTYPE_JASPER },
	{ "IBM Automatic Server Restart - Machine Type 8482", ASMTYPE_JUNIPER },
	{ "IBM Automatic Server Restart - Machine Type 8648", ASMTYPE_SPRUCE },
	{ NULL }
};

static int __init ibmasr_init(void)
{
	struct ibmasr_id *id;
	int rc;

	for (id = ibmasr_id_table; id->desc; id++) {
		if (dmi_find_device(DMI_DEV_TYPE_OTHER, id->desc, NULL)) {
			asr_type = id->type;
			break;
		}
	}

	if (!asr_type)
		return -ENODEV;

	rc = asr_get_base_address();
	if (rc)
		return rc;

	rc = misc_register(&asr_miscdev);
	if (rc < 0) {
		release_region(asr_base, asr_length);
		pr_err("failed to register misc device\n");
		return rc;
	}

	return 0;
}

static void __exit ibmasr_exit(void)
{
	if (!nowayout)
		asr_disable();

	misc_deregister(&asr_miscdev);

	release_region(asr_base, asr_length);
}

module_init(ibmasr_init);
module_exit(ibmasr_exit);

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
	"Watchdog cannot be stopped once started (default="
				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

MODULE_DESCRIPTION("IBM Automatic Server Restart driver");
MODULE_AUTHOR("Andrey Panin");
MODULE_LICENSE("GPL");