diff options
Diffstat (limited to 'drivers/watchdog/at32ap700x_wdt.c')
| -rw-r--r-- | drivers/watchdog/at32ap700x_wdt.c | 69 |
1 files changed, 65 insertions, 4 deletions
diff --git a/drivers/watchdog/at32ap700x_wdt.c b/drivers/watchdog/at32ap700x_wdt.c index 54a516169d0..fb5ed6478f7 100644 --- a/drivers/watchdog/at32ap700x_wdt.c +++ b/drivers/watchdog/at32ap700x_wdt.c @@ -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; |