/*
 * drivers/watchdog/orion_wdt.c
 *
 * Watchdog driver for Orion/Kirkwood processors
 *
 * Author: Sylver Bruneau <sylver.bruneau@googlemail.com>
 *
 * This file is licensed under  the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/clk.h>
#include <mach/bridge-regs.h>

/*
 * Watchdog timer block registers.
 */
#define TIMER_CTRL		0x0000
#define  WDT_EN			0x0010
#define WDT_VAL			0x0024

#define WDT_MAX_CYCLE_COUNT	0xffffffff
#define WDT_IN_USE		0
#define WDT_OK_TO_CLOSE		1

static bool nowayout = WATCHDOG_NOWAYOUT;
static int heartbeat = -1;		/* module parameter (seconds) */
static unsigned int wdt_max_duration;	/* (seconds) */
static struct clk *clk;
static unsigned int wdt_tclk;
static void __iomem *wdt_reg;
static unsigned long wdt_status;
static DEFINE_SPINLOCK(wdt_lock);

static void orion_wdt_ping(void)
{
	spin_lock(&wdt_lock);

	/* Reload watchdog duration */
	writel(wdt_tclk * heartbeat, wdt_reg + WDT_VAL);

	spin_unlock(&wdt_lock);
}

static void orion_wdt_enable(void)
{
	u32 reg;

	spin_lock(&wdt_lock);

	/* Set watchdog duration */
	writel(wdt_tclk * heartbeat, wdt_reg + WDT_VAL);

	/* Clear watchdog timer interrupt */
	reg = readl(BRIDGE_CAUSE);
	reg &= ~WDT_INT_REQ;
	writel(reg, BRIDGE_CAUSE);

	/* Enable watchdog timer */
	reg = readl(wdt_reg + TIMER_CTRL);
	reg |= WDT_EN;
	writel(reg, wdt_reg + TIMER_CTRL);

	/* Enable reset on watchdog */
	reg = readl(RSTOUTn_MASK);
	reg |= WDT_RESET_OUT_EN;
	writel(reg, RSTOUTn_MASK);

	spin_unlock(&wdt_lock);
}

static void orion_wdt_disable(void)
{
	u32 reg;

	spin_lock(&wdt_lock);

	/* Disable reset on watchdog */
	reg = readl(RSTOUTn_MASK);
	reg &= ~WDT_RESET_OUT_EN;
	writel(reg, RSTOUTn_MASK);

	/* Disable watchdog timer */
	reg = readl(wdt_reg + TIMER_CTRL);
	reg &= ~WDT_EN;
	writel(reg, wdt_reg + TIMER_CTRL);

	spin_unlock(&wdt_lock);
}

static int orion_wdt_get_timeleft(int *time_left)
{
	spin_lock(&wdt_lock);
	*time_left = readl(wdt_reg + WDT_VAL) / wdt_tclk;
	spin_unlock(&wdt_lock);
	return 0;
}

static int orion_wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
		return -EBUSY;
	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
	orion_wdt_enable();
	return nonseekable_open(inode, file);
}

static ssize_t orion_wdt_write(struct file *file, const char *data,
					size_t len, loff_t *ppos)
{
	if (len) {
		if (!nowayout) {
			size_t i;

			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
			for (i = 0; i != len; i++) {
				char c;

				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
			}
		}
		orion_wdt_ping();
	}
	return len;
}

static int orion_wdt_settimeout(int new_time)
{
	if ((new_time <= 0) || (new_time > wdt_max_duration))
		return -EINVAL;

	/* Set new watchdog time to be used when
	 * orion_wdt_enable() or orion_wdt_ping() is called. */
	heartbeat = new_time;
	return 0;
}

static const struct watchdog_info ident = {
	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
			  WDIOF_KEEPALIVEPING,
	.identity	= "Orion Watchdog",
};

static long orion_wdt_ioctl(struct file *file, unsigned int cmd,
				unsigned long arg)
{
	int ret = -ENOTTY;
	int time;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		ret = copy_to_user((struct watchdog_info *)arg, &ident,
				   sizeof(ident)) ? -EFAULT : 0;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		ret = put_user(0, (int *)arg);
		break;

	case WDIOC_KEEPALIVE:
		orion_wdt_ping();
		ret = 0;
		break;

	case WDIOC_SETTIMEOUT:
		ret = get_user(time, (int *)arg);
		if (ret)
			break;

		if (orion_wdt_settimeout(time)) {
			ret = -EINVAL;
			break;
		}
		orion_wdt_ping();
		/* Fall through */

	case WDIOC_GETTIMEOUT:
		ret = put_user(heartbeat, (int *)arg);
		break;

	case WDIOC_GETTIMELEFT:
		if (orion_wdt_get_timeleft(&time)) {
			ret = -EINVAL;
			break;
		}
		ret = put_user(time, (int *)arg);
		break;
	}
	return ret;
}

static int orion_wdt_release(struct inode *inode, struct file *file)
{
	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
		orion_wdt_disable();
	else
		pr_crit("Device closed unexpectedly - timer will not stop\n");
	clear_bit(WDT_IN_USE, &wdt_status);
	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

	return 0;
}


static const struct file_operations orion_wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= orion_wdt_write,
	.unlocked_ioctl	= orion_wdt_ioctl,
	.open		= orion_wdt_open,
	.release	= orion_wdt_release,
};

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

static int __devinit orion_wdt_probe(struct platform_device *pdev)
{
	struct resource *res;
	int ret;

	clk = clk_get(&pdev->dev, NULL);
	if (IS_ERR(clk)) {
		printk(KERN_ERR "Orion Watchdog missing clock\n");
		return -ENODEV;
	}
	clk_prepare_enable(clk);
	wdt_tclk = clk_get_rate(clk);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	wdt_reg = ioremap(res->start, resource_size(res));

	if (orion_wdt_miscdev.parent)
		return -EBUSY;
	orion_wdt_miscdev.parent = &pdev->dev;

	wdt_max_duration = WDT_MAX_CYCLE_COUNT / wdt_tclk;
	if (orion_wdt_settimeout(heartbeat))
		heartbeat = wdt_max_duration;

	ret = misc_register(&orion_wdt_miscdev);
	if (ret)
		return ret;

	pr_info("Initial timeout %d sec%s\n",
		heartbeat, nowayout ? ", nowayout" : "");
	return 0;
}

static int __devexit orion_wdt_remove(struct platform_device *pdev)
{
	int ret;

	if (test_bit(WDT_IN_USE, &wdt_status)) {
		orion_wdt_disable();
		clear_bit(WDT_IN_USE, &wdt_status);
	}

	ret = misc_deregister(&orion_wdt_miscdev);
	if (!ret)
		orion_wdt_miscdev.parent = NULL;

	clk_disable_unprepare(clk);
	clk_put(clk);

	return ret;
}

static void orion_wdt_shutdown(struct platform_device *pdev)
{
	if (test_bit(WDT_IN_USE, &wdt_status))
		orion_wdt_disable();
}

static struct platform_driver orion_wdt_driver = {
	.probe		= orion_wdt_probe,
	.remove		= __devexit_p(orion_wdt_remove),
	.shutdown	= orion_wdt_shutdown,
	.driver		= {
		.owner	= THIS_MODULE,
		.name	= "orion_wdt",
	},
};

module_platform_driver(orion_wdt_driver);

MODULE_AUTHOR("Sylver Bruneau <sylver.bruneau@googlemail.com>");
MODULE_DESCRIPTION("Orion Processor Watchdog");

module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");

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

MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);