[PATCH v3] watchdog: it87_wdt: add PWRGD enable quirk for Qotom QCML04

[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.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
Changes v2 -> v3:
  - add linux/bits.h header
  - check for quirks on all it87 chips
Changes v1 -> v2:
  - remove QGLK02/IT87_WDT_BROKEN
---
 drivers/watchdog/it87_wdt.c | 38 +++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/watchdog/it87_wdt.c b/drivers/watchdog/it87_wdt.c
index 3e8c15138edd..03274e48e834 100644
--- a/drivers/watchdog/it87_wdt.c
+++ b/drivers/watchdog/it87_wdt.c
@@ -20,6 +20,8 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/bits.h>
+#include <linux/dmi.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
@@ -40,6 +42,7 @@
 #define VAL		0x2f
 
 /* Logical device Numbers LDN */
+#define EC		0x04
 #define GPIO		0x07
 
 /* Configuration Registers and Functions */
@@ -73,6 +76,12 @@
 #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 +249,20 @@ static int wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
 	return ret;
 }
 
+enum {
+	IT87_WDT_OUTPUT_THROUGH_PWRGD	= BIT(0),
+};
+
+static const struct dmi_system_id it87_quirks[] = {
+	{
+		/* Qotom Q30900P (IT8786) */
+		.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 +284,10 @@ 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 +298,10 @@ static int __init it87_wdt_init(void)
 	chip_rev  = superio_inb(CHIPREV) & 0x0f;
 	superio_exit();
 
+	dmi_id = dmi_first_match(it87_quirks);
+	if (dmi_id)
+		quirks = (long)dmi_id->driver_data;
+
 	switch (chip_type) {
 	case IT8702_ID:
 		max_units = 255;
@@ -333,6 +362,15 @@ 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