[PATCH] watchdog: it87_wdt: add quirks for some Qotom IT8786 boards

[James Hilliard <james.hilliard1@gmail.com>]

For the watchdog timer to work properly on the QCML04 board we need to
set PWRGD enable in the Environment Controller Configuration Registers
Special Configuration Register 1 when it is not already set, this may
be the case when the watchdog is not enabled from within the BIOS.

For the Qotom QGLK02 board the vendor indicates that the IT8786
watchdog hardware is not functional due to a conflict with the BIOS
power-on function, with PWRGD set the watchdog will trigger but the
board will poweroff rather than restart as expected. Disable the
it87 driver on this broken hardware.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/watchdog/it87_wdt.c | 55 +++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/drivers/watchdog/it87_wdt.c b/drivers/watchdog/it87_wdt.c
index 3e8c15138edd..dec501c21fd3 100644
--- a/drivers/watchdog/it87_wdt.c
+++ b/drivers/watchdog/it87_wdt.c
@@ -20,6 +20,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/dmi.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
@@ -40,6 +41,7 @@
 #define VAL		0x2f
 
 /* Logical device Numbers LDN */
+#define EC		0x04
 #define GPIO		0x07
 
 /* Configuration Registers and Functions */
@@ -73,6 +75,12 @@
 #define IT8784_ID	0x8784
 #define IT8786_ID	0x8786
 
+/* Environment Controller Configuration Registers LDN=0x04 */
+#define SCR1		0xfa
+
+/* Environment Controller Bits SCR1 */
+#define WDT_PWRGD	0x20
+
 /* GPIO Configuration Registers LDN=0x07 */
 #define WDTCTRL		0x71
 #define WDTCFG		0x72
@@ -240,6 +248,28 @@ static int wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
 	return ret;
 }
 
+enum {
+	IT87_WDT_BROKEN			= BIT(0),
+	IT87_WDT_OUTPUT_THROUGH_PWRGD	= BIT(1),
+};
+
+static const struct dmi_system_id it8786_quirks[] = {
+	{
+		/* Qotom Q730P/Q8XXG2-P */
+		.matches = {
+			DMI_EXACT_MATCH(DMI_BOARD_NAME, "QGLK02"),
+		},
+		.driver_data = (void *)IT87_WDT_BROKEN,
+	},
+	{
+		/* Qotom Q30900P */
+		.matches = {
+			DMI_EXACT_MATCH(DMI_BOARD_NAME, "QCML04"),
+		},
+		.driver_data = (void *)IT87_WDT_OUTPUT_THROUGH_PWRGD,
+	}
+};
+
 static const struct watchdog_info ident = {
 	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 	.firmware_version = 1,
@@ -261,8 +291,10 @@ static struct watchdog_device wdt_dev = {
 
 static int __init it87_wdt_init(void)
 {
+	const struct dmi_system_id *dmi_id;
 	u8  chip_rev;
 	u8 ctrl;
+	int quirks = 0;
 	int rc;
 
 	rc = superio_enter();
@@ -273,6 +305,20 @@ static int __init it87_wdt_init(void)
 	chip_rev  = superio_inb(CHIPREV) & 0x0f;
 	superio_exit();
 
+	switch (chip_type) {
+	case IT8786_ID:
+		dmi_id = dmi_first_match(it8786_quirks);
+		break;
+	default:
+		dmi_id = NULL;
+	}
+
+	if (dmi_id)
+		quirks = (long)dmi_id->driver_data;
+
+	if (quirks & IT87_WDT_BROKEN)
+		return -ENODEV;
+
 	switch (chip_type) {
 	case IT8702_ID:
 		max_units = 255;
@@ -333,6 +379,15 @@ static int __init it87_wdt_init(void)
 		superio_outb(0x00, WDTCTRL);
 	}
 
+	if (quirks & IT87_WDT_OUTPUT_THROUGH_PWRGD) {
+		superio_select(EC);
+		ctrl = superio_inb(SCR1);
+		if (!(ctrl & WDT_PWRGD)) {
+			ctrl |= WDT_PWRGD;
+			superio_outb(ctrl, SCR1);
+		}
+	}
+
 	superio_exit();
 
 	if (timeout < 1 || timeout > max_units * 60) {
-- 
2.34.1