watchdog: f71808e_wdt: Add F81866 support

Adds watchdog enable support for Fintek F81866 Super-IO chip to
Fintek wdt driver (f71808e_wdt)

Tested and verified on iBASE MI802 Industrial PC

Datasheet references:
http://www.alldatasheet.com/datasheet-pdf/pdf/459085/FINTEK/F81866AD-I.html

Suggested-by: Guenter Roeck <[e-mail]>
Signed-off-by: Ji-Ze Hong (Peter Hong) <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/f71808e_wdt.c

···
 #define SIO_REG_DEVREV		0x22	/* Device revision */
 #define SIO_REG_MANID		0x23	/* Fintek ID (2 bytes) */
 #define SIO_REG_ROM_ADDR_SEL	0x27	/* ROM address select */
+#define SIO_F81866_REG_PORT_SEL	0x27	/* F81866 Multi-Function Register */
 #define SIO_REG_MFUNCT1		0x29	/* Multi function select 1 */
 #define SIO_REG_MFUNCT2		0x2a	/* Multi function select 2 */
 #define SIO_REG_MFUNCT3		0x2b	/* Multi function select 3 */
+#define SIO_F81866_REG_GPIO1	0x2c	/* F81866 GPIO1 Enable Register */
 #define SIO_REG_ENABLE		0x30	/* Logical device enable */
 #define SIO_REG_ADDR		0x60	/* Logical device address (2 bytes) */
 
···
 #define SIO_F71882_ID		0x0541	/* Chipset ID */
 #define SIO_F71889_ID		0x0723	/* Chipset ID */
 #define SIO_F81865_ID		0x0704	/* Chipset ID */
+#define SIO_F81866_ID		0x1010	/* Chipset ID */
 
 #define F71808FG_REG_WDO_CONF		0xf0
 #define F71808FG_REG_WDT_CONF		0xf5
···
 MODULE_PARM_DESC(start_withtimeout, "Start watchdog timer on module load with"
 	" given initial timeout. Zero (default) disables this feature.");
 
-enum chips { f71808fg, f71858fg, f71862fg, f71869, f71882fg, f71889fg, f81865 };
+enum chips { f71808fg, f71858fg, f71862fg, f71869, f71882fg, f71889fg, f81865,
+	     f81866};
 
 static const char *f71808e_names[] = {
 	"f71808fg",
···
 	"f71882fg",
 	"f71889fg",
 	"f81865",
+	"f81866",
 };
 
 /* Super-I/O Function prototypes */
···
 		superio_clear_bit(watchdog.sioaddr, SIO_REG_MFUNCT3, 5);
 		break;
 
+	case f81866:
+		/* Set pin 70 to WDTRST# */
+		superio_clear_bit(watchdog.sioaddr, SIO_F81866_REG_PORT_SEL,
+				  BIT(3) | BIT(0));
+		superio_set_bit(watchdog.sioaddr, SIO_F81866_REG_PORT_SEL,
+				BIT(2));
+		/*
+		 * GPIO1 Control Register when 27h BIT3:2 = 01 & BIT0 = 0.
+		 * The PIN 70(GPIO15/WDTRST) is controlled by 2Ch:
+		 *     BIT5: 0 -> WDTRST#
+		 *           1 -> GPIO15
+		 */
+		superio_clear_bit(watchdog.sioaddr, SIO_F81866_REG_GPIO1,
+				  BIT(5));
+		break;
+
 	default:
 		/*
 		 * 'default' label to shut up the compiler and catch
···
 	superio_select(watchdog.sioaddr, SIO_F71808FG_LD_WDT);
 	superio_set_bit(watchdog.sioaddr, SIO_REG_ENABLE, 0);
 
-	if (watchdog.type == f81865)
+	if (watchdog.type == f81865 || watchdog.type == f81866)
 		superio_set_bit(watchdog.sioaddr, F81865_REG_WDO_CONF,
 				F81865_FLAG_WDOUT_EN);
 	else
···
 		goto exit;
 	case SIO_F81865_ID:
 		watchdog.type = f81865;
+		break;
+	case SIO_F81866_ID:
+		watchdog.type = f81866;
 		break;
 	default:
 		pr_info("Unrecognized Fintek device: %04x\n",