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Commit bb133450 authored by Hans-Christian Egtvedt's avatar Hans-Christian Egtvedt Committed by Wim Van Sebroeck
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[WATCHDOG] at32ap700x_wdt: add support for boot status and add fix for silicon errata 

This patch enables the watchdog to read out the reset cause after a boot and
provide this to the user.

The driver will now also return -EIO if probed when booting from a watchdog
reset. This is due to a silicon errata in the AT32AP700x devices.

Detailed description and work-arounds can be found in the errata section of the
datasheet avilable from
http://www.atmel.com/dyn/products/datasheets.asp?family_id=682



Signed-off-by: default avatarHans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: default avatarWim Van Sebroeck <wim@iguana.be>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 2ffbb837

drivers/watchdog/at32ap700x_wdt.c

+65 −4
Original line number Diff line number Diff line
@@ -6,6 +6,19 @@ 
 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 *

 * Errata: WDT Clear is blocked after WDT Reset

 *

 * A watchdog timer event will, after reset, block writes to the WDT_CLEAR

 * register, preventing the program to clear the next Watchdog Timer Reset.

 *

 * If you still want to use the WDT after a WDT reset a small code can be

 * insterted at the startup checking the AVR32_PM.rcause register for WDT reset

 * and use a GPIO pin to reset the system. This method requires that one of the

 * GPIO pins are available and connected externally to the RESET_N pin. After

 * the GPIO pin has pulled down the reset line the GPIO will be reset and leave

 * the pin tristated with pullup.

 */



#include <linux/init.h>
@@ -44,6 +57,13 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 


#define WDT_CLR			0x04



#define WDT_RCAUSE		0x10

#define WDT_RCAUSE_POR		   0

#define WDT_RCAUSE_EXT		   2

#define WDT_RCAUSE_WDT		   3

#define WDT_RCAUSE_JTAG		   4

#define WDT_RCAUSE_SERP		   5



#define WDT_BIT(name)		(1 << WDT_##name)

#define WDT_BF(name, value)	((value) << WDT_##name)
@@ -56,6 +76,7 @@ struct wdt_at32ap700x { 
	void __iomem		*regs;

	spinlock_t		io_lock;

	int			timeout;

	int			boot_status;

	unsigned long		users;

	struct miscdevice	miscdev;

};
@@ -126,7 +147,7 @@ static int at32_wdt_close(struct inode *inode, struct file *file) 
		at32_wdt_stop();

	} else {

		dev_dbg(wdt->miscdev.parent,

			"Unexpected close, not stopping watchdog!\n");

			"unexpected close, not stopping watchdog!\n");

		at32_wdt_pat();

	}

	clear_bit(1, &wdt->users);
@@ -154,6 +175,33 @@ static int at32_wdt_settimeout(int time) 
	return 0;

}



/*

 * Get the watchdog status.

 */

static int at32_wdt_get_status(void)

{

	int rcause;

	int status = 0;



	rcause = wdt_readl(wdt, RCAUSE);



	switch (rcause) {

	case WDT_BIT(RCAUSE_EXT):

		status = WDIOF_EXTERN1;

		break;

	case WDT_BIT(RCAUSE_WDT):

		status = WDIOF_CARDRESET;

		break;

	case WDT_BIT(RCAUSE_POR):  /* fall through */

	case WDT_BIT(RCAUSE_JTAG): /* fall through */

	case WDT_BIT(RCAUSE_SERP): /* fall through */

	default:

		break;

	}



	return status;

}



static struct watchdog_info at32_wdt_info = {

	.identity	= "at32ap700x watchdog",

	.options	= WDIOF_SETTIMEOUT |
@@ -194,10 +242,12 @@ static int at32_wdt_ioctl(struct inode *inode, struct file *file, 
	case WDIOC_GETTIMEOUT:

		ret = put_user(wdt->timeout, p);

		break;

	case WDIOC_GETSTATUS: /* fall through */

	case WDIOC_GETBOOTSTATUS:

	case WDIOC_GETSTATUS:

		ret = put_user(0, p);

		break;

	case WDIOC_GETBOOTSTATUS:

		ret = put_user(wdt->boot_status, p);

		break;

	case WDIOC_SETOPTIONS:

		ret = get_user(time, p);

		if (ret)
@@ -282,8 +332,19 @@ static int __init at32_wdt_probe(struct platform_device *pdev) 
		dev_dbg(&pdev->dev, "could not map I/O memory\n");

		goto err_free;

	}



	spin_lock_init(&wdt->io_lock);

	wdt->boot_status = at32_wdt_get_status();



	/* Work-around for watchdog silicon errata. */

	if (wdt->boot_status & WDIOF_CARDRESET) {

		dev_info(&pdev->dev, "CPU must be reset with external "

				"reset or POR due to silicon errata.\n");

		ret = -EIO;

		goto err_iounmap;

	} else {

		wdt->users = 0;

	}

	wdt->miscdev.minor = WATCHDOG_MINOR;

	wdt->miscdev.name = "watchdog";

	wdt->miscdev.fops = &at32_wdt_fops;