watchdog: w83627hf_wdt: add bootstatus support

The status bit in the status and control register can tell us whether
the last reboot was caused by the watchdog. Make sure to take that into
the bootstatus before clearing it.

Signed-off-by: Henning Schild <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/w83627hf_wdt.c

···
 #define W836X7HF_WDT_CSR	0xf7
 #define NCT6102D_WDT_CSR	0xf2
 
+#define WDT_CSR_STATUS		0x10
+#define WDT_CSR_KBD		0x40
+#define WDT_CSR_MOUSE		0x80
+
 static void superio_outb(int reg, int val)
 {
 	outb(reg, WDT_EFER);
···
 	t = superio_inb(cr_wdt_control) & ~0x0C;
 	superio_outb(cr_wdt_control, t);
 
-	/* reset trigger, disable keyboard & mouse turning off watchdog */
-	t = superio_inb(cr_wdt_csr) & ~0xD0;
+	t = superio_inb(cr_wdt_csr);
+	if (t & WDT_CSR_STATUS)
+		wdog->bootstatus |= WDIOF_CARDRESET;
+
+	/* reset status, disable keyboard & mouse turning off watchdog */
+	t &= ~(WDT_CSR_STATUS | WDT_CSR_KBD | WDT_CSR_MOUSE);
 	superio_outb(cr_wdt_csr, t);
 
 	superio_exit();