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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: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Hans-Christian Egtvedt 2007-10-30 14:56:20 +01:00 committed by Wim Van Sebroeck
parent 2ffbb8377c
commit bb133450ee
1 changed files with 65 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

69
drivers/watchdog/at32ap700x_wdt.c
View File

@ -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->users = 0;
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;