[PATCH v2 0/3] Update ASPEED WDT bootstatus

[PATCH v2 0/3] 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/
Besides, the boot status modififed in the WDT driver
obeys the rules proposed in the OpenBMC.
https://github.com/openbmc/docs/blob/master/designs/bmc-reboot-cause-update.md#proposed-design
Moreover, WDT SW restart mechanism is supported by HW
since AST2600 platform and is also included in this
patch series.

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


Chin-Ting Kuo (3):
  ARM: dts: aspeed: Add WDT controller into alias field
  watchdog: aspeed: Update bootstatus handling
  watchdog: aspeed: Add support for SW restart

 arch/arm/boot/dts/aspeed/aspeed-g4.dtsi |   2 +
 arch/arm/boot/dts/aspeed/aspeed-g5.dtsi |   3 +
 arch/arm/boot/dts/aspeed/aspeed-g6.dtsi |   4 +
 drivers/watchdog/aspeed_wdt.c           | 149 ++++++++++++++++++++++--
 4 files changed, 150 insertions(+), 8 deletions(-)

-- 
2.34.1

[PATCH v2 1/3] ARM: dts: aspeed: Add WDT controller into alias field

[Chin-Ting Kuo]

Add WDT controller into alias field. After that, WDT index,
used to distinguish different WDT controllers in the driver,
can be gotten by using of_alias_get_id dts API.

Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
---
 arch/arm/boot/dts/aspeed/aspeed-g4.dtsi | 2 ++
 arch/arm/boot/dts/aspeed/aspeed-g5.dtsi | 3 +++
 arch/arm/boot/dts/aspeed/aspeed-g6.dtsi | 4 ++++
 3 files changed, 9 insertions(+)

diff --git a/arch/arm/boot/dts/aspeed/aspeed-g4.dtsi b/arch/arm/boot/dts/aspeed/aspeed-g4.dtsi
index 78c967812492..d8b4136d0ca0 100644
--- a/arch/arm/boot/dts/aspeed/aspeed-g4.dtsi
+++ b/arch/arm/boot/dts/aspeed/aspeed-g4.dtsi
@@ -29,6 +29,8 @@ aliases {
 		serial3 = &uart4;
 		serial4 = &uart5;
 		serial5 = &vuart;
+		watchdog0 = &wdt1;
+		watchdog1 = &wdt2;
 	};
 
 	cpus {
diff --git a/arch/arm/boot/dts/aspeed/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed/aspeed-g5.dtsi
index 57a699a7c149..4dd220bca617 100644
--- a/arch/arm/boot/dts/aspeed/aspeed-g5.dtsi
+++ b/arch/arm/boot/dts/aspeed/aspeed-g5.dtsi
@@ -30,6 +30,9 @@ aliases {
 		serial3 = &uart4;
 		serial4 = &uart5;
 		serial5 = &vuart;
+		watchdog0 = &wdt1;
+		watchdog1 = &wdt2;
+		watchdog2 = &wdt3;
 	};
 
 	cpus {
diff --git a/arch/arm/boot/dts/aspeed/aspeed-g6.dtsi b/arch/arm/boot/dts/aspeed/aspeed-g6.dtsi
index 8ed715bd53aa..c0a47c795fff 100644
--- a/arch/arm/boot/dts/aspeed/aspeed-g6.dtsi
+++ b/arch/arm/boot/dts/aspeed/aspeed-g6.dtsi
@@ -40,6 +40,10 @@ aliases {
 		mdio1 = &mdio1;
 		mdio2 = &mdio2;
 		mdio3 = &mdio3;
+		watchdog0 = &wdt1;
+		watchdog1 = &wdt2;
+		watchdog2 = &wdt3;
+		watchdog3 = &wdt4;
 	};
 
 
-- 
2.34.1

[PATCH v2 2/3] watchdog: aspeed: Update bootstatus handling

[Chin-Ting Kuo]

Update the bootstatus according to 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

In short,
- WDIOF_EXTERN1   => system is reset by Software
- WDIOF_CARDRESET => system is reset by WDT
- Others          => other reset events, e.g., power on reset.

On AST2400 platform, only a bit, SCU3C[1], represents that the
system is reset by WDT1 or WDT2.

On AST2500 platform, SCU3C[4:2] are WDT reset flags.
  SCU3C[4]: system is reset by WDT3.
  SCU3C[3]: system is reset by WDT2.
  SCU3C[2]: system is reset by WDT1.

On AST2600 platform, SCU074[31:16] are WDT reset flags.
  SCU074[31:28]: system is reset by WDT4
    SCU074[31]: system is reset by WDT4 software reset.
  SCU074[27:24]: system is reset by WDT3
    SCU074[27]: system is reset by WDT3 software reset.
  SCU074[23:20]: system is reset by WDT2
    SCU074[23]: system is reset by WDT2 software reset.
  SCU074[19:16]: system is reset by WDT1
    SCU074[19]: system is reset by WDT1 software reset.

Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
---
 drivers/watchdog/aspeed_wdt.c | 109 +++++++++++++++++++++++++++++++---
 1 file changed, 101 insertions(+), 8 deletions(-)

diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index b4773a6aaf8c..a0c03a949173 100644
--- a/drivers/watchdog/aspeed_wdt.c
+++ b/drivers/watchdog/aspeed_wdt.c
@@ -11,10 +11,12 @@
 #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;
@@ -22,15 +24,41 @@ module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
+
+/* AST SCU Register for System Reset Event Log Register Set
+ * ast2600 is scu074 ast2400/2500 is scu03c
+ */
+#define AST2400_SCU_SYS_RESET_STATUS	0x3c
+#define   AST2400_SCU_SYS_RESET_WDT_MASK	0x1
+#define   AST2400_SCU_SYS_RESET_WDT_MASK_SHIFT	1
+
+#define   AST2500_SCU_SYS_RESET_WDT_MASK	0x1
+#define   AST2500_SCU_SYS_RESET_WDT_MASK_SHIFT	2
+
+#define AST2600_SCU_SYS_RESET_STATUS	0x74
+#define   AST2600_SCU_SYS_RESET_WDT_MASK	0xf
+#define   AST2600_SCU_SYS_RESET_WDT_SW_MASK	0x8
+#define   AST2600_SCU_SYS_RESET_WDT_MASK_SHIFT	16
+
+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 {
 	struct watchdog_device	wdd;
 	void __iomem		*base;
+	int			idx;
 	u32			ctrl;
 	const struct aspeed_wdt_config *cfg;
 };
@@ -39,18 +67,39 @@ 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 = AST2400_SCU_SYS_RESET_STATUS,
+		.wdt_reset_mask = AST2400_SCU_SYS_RESET_WDT_MASK,
+		.wdt_sw_reset_mask = 0,
+		.wdt_reset_mask_shift = AST2400_SCU_SYS_RESET_WDT_MASK_SHIFT,
+	},
 };
 
 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 = AST2400_SCU_SYS_RESET_STATUS,
+		.wdt_reset_mask = AST2500_SCU_SYS_RESET_WDT_MASK,
+		.wdt_sw_reset_mask = 0,
+		.wdt_reset_mask_shift = AST2500_SCU_SYS_RESET_WDT_MASK_SHIFT,
+	},
 };
 
 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 = AST2600_SCU_SYS_RESET_STATUS,
+		.wdt_reset_mask = AST2600_SCU_SYS_RESET_WDT_MASK,
+		.wdt_sw_reset_mask = AST2600_SCU_SYS_RESET_WDT_SW_MASK,
+		.wdt_reset_mask_shift = AST2600_SCU_SYS_RESET_WDT_MASK_SHIFT,
+	},
 };
 
 static const struct of_device_id aspeed_wdt_of_table[] = {
@@ -213,6 +262,52 @@ static int aspeed_wdt_restart(struct watchdog_device *wdd,
 	return 0;
 }
 
+static int aspeed_wdt_get_bootstatus(struct device *dev,
+				     struct aspeed_wdt *wdt)
+{
+	struct device_node *np = dev->of_node;
+	struct aspeed_wdt_scu scu = wdt->cfg->scu;
+	struct regmap *scu_base;
+	u32 reset_mask_width;
+	u32 reset_mask_shift;
+	u32 status;
+	int ret;
+
+	wdt->idx = of_alias_get_id(np, "watchdog");
+	if (wdt->idx < 0)
+		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;
+
+	/* On AST2400, only a bit used to represent WDT reset */
+	if (of_device_is_compatible(np, "aspeed,ast2400-wdt"))
+		wdt->idx = 0;
+
+	reset_mask_width = hweight32(scu.wdt_reset_mask);
+	reset_mask_shift = scu.wdt_reset_mask_shift +
+			   reset_mask_width * wdt->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;
+
+	ret = regmap_write(scu_base, scu.reset_status_reg,
+			   scu.wdt_reset_mask << reset_mask_shift);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 /* 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)
@@ -312,7 +407,6 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 	struct device_node *np;
 	const char *reset_type;
 	u32 duration;
-	u32 status;
 	int ret;
 
 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
@@ -458,14 +552,13 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 		writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
 	}
 
-	status = readl(wdt->base + WDT_TIMEOUT_STATUS);
-	if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) {
-		wdt->wdd.bootstatus = WDIOF_CARDRESET;
+	ret = aspeed_wdt_get_bootstatus(dev, wdt);
+	if (ret)
+		return ret;
 
-		if (of_device_is_compatible(np, "aspeed,ast2400-wdt") ||
-		    of_device_is_compatible(np, "aspeed,ast2500-wdt"))
-			wdt->wdd.groups = bswitch_groups;
-	}
+	if (of_device_is_compatible(np, "aspeed,ast2400-wdt") ||
+	    of_device_is_compatible(np, "aspeed,ast2500-wdt"))
+		wdt->wdd.groups = bswitch_groups;
 
 	dev_set_drvdata(dev, wdt);
 
-- 
2.34.1

[PATCH v2 3/3] watchdog: aspeed: Add support for SW restart

[Chin-Ting Kuo]

Since AST2600, except for HW WDT counter timeout, HW WDT
reset can also be triggered by just cinfiguring some
HW registers by SW directly. We named it "SW restart".
Although it is "SW" restart, its mechanism is implemented
by HW.

Originally, system can only know it is reset by WDT
through a reset flag. However, since AST2600, SW can
trigger the reset event consciously and directly without
wait for WDT timeout. WDT counter is not enabled when
SW restart is adopted. After that, an independent reset
event flag will be set after systemis reset by SW.

Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
---
 drivers/watchdog/aspeed_wdt.c | 40 +++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index a0c03a949173..9ba9b7346d44 100644
--- a/drivers/watchdog/aspeed_wdt.c
+++ b/drivers/watchdog/aspeed_wdt.c
@@ -40,6 +40,9 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 #define   AST2600_SCU_SYS_RESET_WDT_SW_MASK	0x8
 #define   AST2600_SCU_SYS_RESET_WDT_MASK_SHIFT	16
 
+/* WDT behavior control flag */
+#define WDT_RESTART_SYSTEM_SW_SUPPORT	0x00000001
+
 struct aspeed_wdt_scu {
 	const char *compatible;
 	u32 reset_status_reg;
@@ -53,6 +56,7 @@ struct aspeed_wdt_config {
 	u32 irq_shift;
 	u32 irq_mask;
 	struct aspeed_wdt_scu scu;
+	u32 flags;
 };
 
 struct aspeed_wdt {
@@ -67,6 +71,7 @@ static const struct aspeed_wdt_config ast2400_config = {
 	.ext_pulse_width_mask = 0xff,
 	.irq_shift = 0,
 	.irq_mask = 0,
+	.flags = 0,
 	.scu = {
 		.compatible = "aspeed,ast2400-scu",
 		.reset_status_reg = AST2400_SCU_SYS_RESET_STATUS,
@@ -80,6 +85,7 @@ static const struct aspeed_wdt_config ast2500_config = {
 	.ext_pulse_width_mask = 0xfffff,
 	.irq_shift = 12,
 	.irq_mask = GENMASK(31, 12),
+	.flags = 0,
 	.scu = {
 		.compatible = "aspeed,ast2500-scu",
 		.reset_status_reg = AST2400_SCU_SYS_RESET_STATUS,
@@ -93,6 +99,7 @@ static const struct aspeed_wdt_config ast2600_config = {
 	.ext_pulse_width_mask = 0xfffff,
 	.irq_shift = 0,
 	.irq_mask = GENMASK(31, 10),
+	.flags = WDT_RESTART_SYSTEM_SW_SUPPORT,
 	.scu = {
 		.compatible = "aspeed,ast2600-scu",
 		.reset_status_reg = AST2600_SCU_SYS_RESET_STATUS,
@@ -130,6 +137,11 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
 #define   WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION	BIT(0)
 #define WDT_RESET_MASK1		0x1c
 #define WDT_RESET_MASK2		0x20
+#define WDT_SW_RESET_CTRL	0x24
+#define   WDT_SW_RESET_COUNT_CLEAR	0xDEADDEAD
+#define   WDT_SW_RESET_ENABLE	0xAEEDF123
+#define WDT_SW_RESET_MASK1	0x28
+#define WDT_SW_RESET_MASK2	0x2c
 
 /*
  * WDT_RESET_WIDTH controls the characteristics of the external pulse (if
@@ -249,10 +261,31 @@ static int aspeed_wdt_set_pretimeout(struct watchdog_device *wdd,
 	return 0;
 }
 
+static void aspeed_wdt_sw_reset(struct watchdog_device *wdd)
+{
+	struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
+	u32 ctrl = WDT_CTRL_RESET_MODE_SOC |
+		   WDT_CTRL_RESET_SYSTEM;
+
+	writel(ctrl, wdt->base + WDT_CTRL);
+	writel(WDT_SW_RESET_COUNT_CLEAR,
+	       wdt->base + WDT_SW_RESET_CTRL);
+	writel(WDT_SW_RESET_ENABLE, wdt->base + WDT_SW_RESET_CTRL);
+
+	/* system must be reset immediately */
+	mdelay(1000);
+}
+
 static int aspeed_wdt_restart(struct watchdog_device *wdd,
 			      unsigned long action, void *data)
 {
 	struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
+	struct aspeed_wdt_config *cfg = wdt->cfg;
+
+	if (cfg->flags & WDT_RESTART_SYSTEM_SW_SUPPORT) {
+		aspeed_wdt_sw_reset(wdd);
+		return 0;
+	}
 
 	wdt->ctrl &= ~WDT_CTRL_BOOT_SECONDARY;
 	aspeed_wdt_enable(wdt, 128 * WDT_RATE_1MHZ / 1000);
@@ -524,6 +557,13 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 			if (nrstmask > 1)
 				writel(reset_mask[1], wdt->base + WDT_RESET_MASK2);
 		}
+
+		if (wdt->cfg->flags & WDT_RESTART_SYSTEM_SW_SUPPORT) {
+			reg = readl(wdt->base + WDT_RESET_MASK1);
+			writel(reg, wdt->base + WDT_SW_RESET_MASK1);
+			reg = readl(wdt->base + WDT_RESET_MASK2);
+			writel(reg, wdt->base + WDT_SW_RESET_MASK2);
+		}
 	}
 
 	if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) {
-- 
2.34.1

Re: [PATCH v2 1/3] ARM: dts: aspeed: Add WDT controller into alias field

[Andrew Jeffery]

On Mon, 2024-10-28 at 10:48 +0800, Chin-Ting Kuo wrote:
> Add WDT controller into alias field. After that, WDT index,
> used to distinguish different WDT controllers in the driver,
> can be gotten by using of_alias_get_id dts API.

I feel it would be less brittle if we encode the mapping in the driver?
Based on reg the driver can derive the watchdog index. That way there's
no constraint on how the platform architect arranges the aliases for
the watchdogs (if they define them at all).

Andrew

RE: [PATCH v2 1/3] ARM: dts: aspeed: Add WDT controller into alias field

[Chin-Ting Kuo]

Hi Andrew,

Thanks for the check.

> -----Original Message-----
> From: Andrew Jeffery <andrew@codeconstruct.com.au>
> Sent: Tuesday, October 29, 2024 7:55 AM
> Subject: Re: [PATCH v2 1/3] ARM: dts: aspeed: Add WDT controller into alias
> field
> 
> On Mon, 2024-10-28 at 10:48 +0800, Chin-Ting Kuo wrote:
> > Add WDT controller into alias field. After that, WDT index, used to
> > distinguish different WDT controllers in the driver, can be gotten by
> > using of_alias_get_id dts API.
> 
> I feel it would be less brittle if we encode the mapping in the driver?
> Based on reg the driver can derive the watchdog index. That way there's no
> constraint on how the platform architect arranges the aliases for the
> watchdogs (if they define them at all).
> 

It is also a feasible approach. It will be changed in the next patch version.

> Andrew

Chin-Ting