[PATCH v7 0/1] Update ASPEED WDT bootstatus

[PATCH v7 0/1] Update ASPEED WDT bootstatus

[Chin-Ting Kuo]

This patch series inherits the patch submitted by Peter.
https://patchwork.kernel.org/project/linux-watchdog/patch/20240430143114.1323686-2-peteryin.openbmc@gmail.com/
Bootstatus mechanism is reconstructed to the latest
architecture and for all existing ASPEED BMC platforms.

Changes in v2:
  - Support SW restart on AST2600 by default without
    adding any dts property.

Changes in v3:
  - Get watchdog controller index by dividing register
    base offset by register size.

Changes in v4:
  - Update the commit message for updating bootstatus
    handling patch.
  - Rename aspeed_wdt_config struct to aspeed_wdt_data.
  - Create restart callback function.

Changes in v5:
  - Remove SW reset mechanism since there is no consensus
    about bootstatus for SW reset currently.
  - Correct the method for clearing reset event flag on
    AST2400 and AST2500 legacy platforms.

Changes in v6:
  - Use resource_size() function to get WDT controller
    registers size.

Changes in v7:
  - Update commit message. WDIOF_CARDRESET flag is
    used to represent all WDT reset events.

Chin-Ting Kuo (1):
  watchdog: aspeed: Update bootstatus handling

 drivers/watchdog/aspeed_wdt.c | 81 ++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 2 deletions(-)

-- 
2.34.1

[PATCH v7 1/1] watchdog: aspeed: Update bootstatus handling

[Chin-Ting Kuo]

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 bootstatus can be,
WDIOF_CARDRESET => System is reset due to WDT timeout occurs.
Others          => Other reset events, e.g., power on reset.

On ASPEED platforms, boot status is recorded in the SCU registers.
- AST2400: Only a bit is used to represent system reset triggered by
           any WDT controller.
- AST2500/AST2600: System reset triggered by different WDT controllers
                   can be distinguished by different SCU bits.

Besides, on AST2400 and AST2500, since alternating boot event is
also triggered by using WDT timeout mechanism, it is classified
as WDIOF_CARDRESET.

Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
---
 drivers/watchdog/aspeed_wdt.c | 81 ++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index b4773a6aaf8c..369635b38ca0 100644
--- a/drivers/watchdog/aspeed_wdt.c
+++ b/drivers/watchdog/aspeed_wdt.c
@@ -11,21 +11,30 @@
 #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_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 +48,36 @@ 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_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_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_reset_mask_shift = 16,
+	},
 };
 
 static const struct of_device_id aspeed_wdt_of_table[] = {
@@ -213,6 +240,56 @@ static int aspeed_wdt_restart(struct watchdog_device *wdd,
 	return 0;
 }
 
+static void aspeed_wdt_update_bootstatus(struct platform_device *pdev,
+					 struct aspeed_wdt *wdt)
+{
+	const struct resource *res;
+	struct aspeed_wdt_scu scu = wdt->cfg->scu;
+	struct regmap *scu_base;
+	u32 reset_mask_width;
+	u32 reset_mask_shift;
+	u32 idx = 0;
+	u32 status;
+	int ret;
+
+	if (!of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2400-wdt")) {
+		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+		idx = ((intptr_t)wdt->base & 0x00000fff) / resource_size(res);
+	}
+
+	scu_base = syscon_regmap_lookup_by_compatible(scu.compatible);
+	if (IS_ERR(scu_base)) {
+		wdt->wdd.bootstatus = WDIOS_UNKNOWN;
+		return;
+	}
+
+	ret = regmap_read(scu_base, scu.reset_status_reg, &status);
+	if (ret) {
+		wdt->wdd.bootstatus = WDIOS_UNKNOWN;
+		return;
+	}
+
+	reset_mask_width = hweight32(scu.wdt_reset_mask);
+	reset_mask_shift = scu.wdt_reset_mask_shift +
+			   reset_mask_width * idx;
+
+	if (status & (scu.wdt_reset_mask << reset_mask_shift))
+		wdt->wdd.bootstatus = WDIOF_CARDRESET;
+
+	/* clear wdt reset event flag */
+	if (of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2400-wdt") ||
+	    of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2500-wdt")) {
+		ret = regmap_read(scu_base, scu.reset_status_reg, &status);
+		if (!ret) {
+			status &= ~(scu.wdt_reset_mask << reset_mask_shift);
+			regmap_write(scu_base, scu.reset_status_reg, status);
+		}
+	} else {
+		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 +535,10 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 		writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
 	}
 
+	aspeed_wdt_update_bootstatus(pdev, wdt);
+
 	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

Re: [PATCH v7 1/1] watchdog: aspeed: Update bootstatus handling

[Andrew Jeffery]

On Mon, 2025-01-13 at 17:37 +0800, Chin-Ting Kuo wrote:
> 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 bootstatus can be,
> WDIOF_CARDRESET => System is reset due to WDT timeout occurs.
> Others          => Other reset events, e.g., power on reset.
> 
> On ASPEED platforms, boot status is recorded in the SCU registers.
> - AST2400: Only a bit is used to represent system reset triggered by
>            any WDT controller.
> - AST2500/AST2600: System reset triggered by different WDT
> controllers
>                    can be distinguished by different SCU bits.
> 
> Besides, on AST2400 and AST2500, since alternating boot event is
> also triggered by using WDT timeout mechanism, it is classified
> as WDIOF_CARDRESET.
> 
> Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>

Reviewed-by: Andrew Jeffery <andrew@codeconstruct.com.au>

Re: [PATCH v7 1/1] watchdog: aspeed: Update bootstatus handling

[Nathan Chancellor]

On Mon, Jan 13, 2025 at 05:37:37PM +0800, Chin-Ting Kuo wrote:
> 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 bootstatus can be,
> WDIOF_CARDRESET => System is reset due to WDT timeout occurs.
> Others          => Other reset events, e.g., power on reset.
> 
> On ASPEED platforms, boot status is recorded in the SCU registers.
> - AST2400: Only a bit is used to represent system reset triggered by
>            any WDT controller.
> - AST2500/AST2600: System reset triggered by different WDT controllers
>                    can be distinguished by different SCU bits.
> 
> Besides, on AST2400 and AST2500, since alternating boot event is
> also triggered by using WDT timeout mechanism, it is classified
> as WDIOF_CARDRESET.
> 
> Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
> ---
>  drivers/watchdog/aspeed_wdt.c | 81 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 79 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
...
> +static void aspeed_wdt_update_bootstatus(struct platform_device *pdev,
> +					 struct aspeed_wdt *wdt)
> +{
> +	const struct resource *res;
> +	struct aspeed_wdt_scu scu = wdt->cfg->scu;
> +	struct regmap *scu_base;
> +	u32 reset_mask_width;
> +	u32 reset_mask_shift;
> +	u32 idx = 0;
> +	u32 status;
> +	int ret;
> +
> +	if (!of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2400-wdt")) {
> +		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +		idx = ((intptr_t)wdt->base & 0x00000fff) / resource_size(res);

This division breaks the build when CONFIG_ARM_LPAE is enabled, which
selects CONFIG_PHYS_ADDR_T_64BIT, turning resource_size_t into a 64-bit
type.

$ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- mrproper multi_v7_lpae_defconfig all
arm-linux-gnueabi-ld: drivers/watchdog/aspeed_wdt.o: in function `aspeed_wdt_update_bootstatus':
drivers/watchdog/aspeed_wdt.c:257:(.text+0x80c): undefined reference to `__aeabi_uldivmod'

> +	}
> +
> +	scu_base = syscon_regmap_lookup_by_compatible(scu.compatible);
> +	if (IS_ERR(scu_base)) {
> +		wdt->wdd.bootstatus = WDIOS_UNKNOWN;
> +		return;
> +	}
> +
> +	ret = regmap_read(scu_base, scu.reset_status_reg, &status);
> +	if (ret) {
> +		wdt->wdd.bootstatus = WDIOS_UNKNOWN;
> +		return;
> +	}
> +
> +	reset_mask_width = hweight32(scu.wdt_reset_mask);
> +	reset_mask_shift = scu.wdt_reset_mask_shift +
> +			   reset_mask_width * idx;
> +
> +	if (status & (scu.wdt_reset_mask << reset_mask_shift))
> +		wdt->wdd.bootstatus = WDIOF_CARDRESET;
> +
> +	/* clear wdt reset event flag */
> +	if (of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2400-wdt") ||
> +	    of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2500-wdt")) {
> +		ret = regmap_read(scu_base, scu.reset_status_reg, &status);
> +		if (!ret) {
> +			status &= ~(scu.wdt_reset_mask << reset_mask_shift);
> +			regmap_write(scu_base, scu.reset_status_reg, status);
> +		}
> +	} else {
> +		regmap_write(scu_base, scu.reset_status_reg,
> +			     scu.wdt_reset_mask << reset_mask_shift);
> +	}
> +}
> +

Cheers,
Nathan