[PATCH v4 1/3] watchdog: aspeed: Update bootstatus handling

[Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>]

The boot status in the watchdog device struct is updated during
controller probe stage. Application layer can get the boot status
through the command, cat /sys/class/watchdog/watchdogX/bootstatus.

The boot status mapping rule follows the latest design guide from
the OpenBMC shown as below.
https://github.com/openbmc/docs/blob/master/designs/bmc-reboot-cause-update.md#proposed-design
- WDIOF_EXTERN1   => system is reset by Software
- WDIOF_CARDRESET => system is reset by WDT SoC reset
- Others          => other reset events, e.g., power on reset.

On ASPEED platform, the boot status is recorded in the SCU registers.
- AST2400: Only a bit represents for any WDT reset.
- AST2500: The reset triggered by different WDT controllers can be
           distinguished by different SCU bits. But, WDIOF_EXTERN1 or
           WDIOF_CARDRESET still cannot be identified due to
           HW limitation.
- AST2600: Different from AST2500, additional HW bits are added for
           distinguishing WDIOF_EXTERN1 and WDIOF_CARDRESET.

Besides, since alternating boot event is triggered by WDT SoC reset,
it is classified as WDIOF_CARDRESET.

Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
---
 drivers/watchdog/aspeed_wdt.c | 83 ++++++++++++++++++++++++++++++++++-
 1 file changed, 81 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index b4773a6aaf8c..4ad6335ff25b 100644
--- a/drivers/watchdog/aspeed_wdt.c
+++ b/drivers/watchdog/aspeed_wdt.c
@@ -11,21 +11,31 @@
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/kstrtox.h>
+#include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/platform_device.h>
+#include <linux/regmap.h>
 #include <linux/watchdog.h>
 
 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+struct aspeed_wdt_scu {
+	const char *compatible;
+	u32 reset_status_reg;
+	u32 wdt_reset_mask;
+	u32 wdt_sw_reset_mask;
+	u32 wdt_reset_mask_shift;
+};
 
 struct aspeed_wdt_config {
 	u32 ext_pulse_width_mask;
 	u32 irq_shift;
 	u32 irq_mask;
+	struct aspeed_wdt_scu scu;
 };
 
 struct aspeed_wdt {
@@ -39,18 +49,39 @@ static const struct aspeed_wdt_config ast2400_config = {
 	.ext_pulse_width_mask = 0xff,
 	.irq_shift = 0,
 	.irq_mask = 0,
+	.scu = {
+		.compatible = "aspeed,ast2400-scu",
+		.reset_status_reg = 0x3c,
+		.wdt_reset_mask = 0x1,
+		.wdt_sw_reset_mask = 0,
+		.wdt_reset_mask_shift = 1,
+	},
 };
 
 static const struct aspeed_wdt_config ast2500_config = {
 	.ext_pulse_width_mask = 0xfffff,
 	.irq_shift = 12,
 	.irq_mask = GENMASK(31, 12),
+	.scu = {
+		.compatible = "aspeed,ast2500-scu",
+		.reset_status_reg = 0x3c,
+		.wdt_reset_mask = 0x1,
+		.wdt_sw_reset_mask = 0,
+		.wdt_reset_mask_shift = 2,
+	},
 };
 
 static const struct aspeed_wdt_config ast2600_config = {
 	.ext_pulse_width_mask = 0xfffff,
 	.irq_shift = 0,
 	.irq_mask = GENMASK(31, 10),
+	.scu = {
+		.compatible = "aspeed,ast2600-scu",
+		.reset_status_reg = 0x74,
+		.wdt_reset_mask = 0xf,
+		.wdt_sw_reset_mask = 0x8,
+		.wdt_reset_mask_shift = 16,
+	},
 };
 
 static const struct of_device_id aspeed_wdt_of_table[] = {
@@ -213,6 +244,52 @@ static int aspeed_wdt_restart(struct watchdog_device *wdd,
 	return 0;
 }
 
+static int aspeed_wdt_update_bootstatus(struct platform_device *pdev,
+					struct aspeed_wdt *wdt)
+{
+	struct resource *res;
+	struct aspeed_wdt_scu scu = wdt->cfg->scu;
+	struct regmap *scu_base;
+	u32 reset_mask_width;
+	u32 reset_mask_shift;
+	u32 reg_size = 0;
+	u32 idx = 0;
+	u32 status;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	reg_size = res->end - res->start;
+
+	if (reg_size != 0)
+		idx = ((intptr_t)wdt->base & 0x00000fff) / reg_size;
+
+	/* On ast2400, only a bit is used to represent WDT reset */
+	if (of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2400-wdt"))
+		idx = 0;
+
+	scu_base = syscon_regmap_lookup_by_compatible(scu.compatible);
+	if (IS_ERR(scu_base))
+		return PTR_ERR(scu_base);
+
+	ret = regmap_read(scu_base, scu.reset_status_reg, &status);
+	if (ret)
+		return ret;
+
+	reset_mask_width = hweight32(scu.wdt_reset_mask);
+	reset_mask_shift = scu.wdt_reset_mask_shift +
+			   reset_mask_width * idx;
+
+	if (status & (scu.wdt_sw_reset_mask << reset_mask_shift))
+		wdt->wdd.bootstatus = WDIOF_EXTERN1;
+	else if (status & (scu.wdt_reset_mask << reset_mask_shift))
+		wdt->wdd.bootstatus = WDIOF_CARDRESET;
+	else
+		wdt->wdd.bootstatus = 0;
+
+	return regmap_write(scu_base, scu.reset_status_reg,
+			    scu.wdt_reset_mask << reset_mask_shift);
+}
+
 /* access_cs0 shows if cs0 is accessible, hence the reverted bit */
 static ssize_t access_cs0_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
@@ -458,10 +535,12 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 		writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
 	}
 
+	ret = aspeed_wdt_update_bootstatus(pdev, wdt);
+	if (ret)
+		return ret;
+
 	status = readl(wdt->base + WDT_TIMEOUT_STATUS);
 	if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) {
-		wdt->wdd.bootstatus = WDIOF_CARDRESET;
-
 		if (of_device_is_compatible(np, "aspeed,ast2400-wdt") ||
 		    of_device_is_compatible(np, "aspeed,ast2500-wdt"))
 			wdt->wdd.groups = bswitch_groups;
-- 
2.34.1