[PATCH v2 0/4] clocksource/drivers/timer-vt8500: clean up and add watchdog function

[PATCH v2 0/4] clocksource/drivers/timer-vt8500: clean up and add watchdog function

[Alexey Charkov]

Add named defines for all registers and bits in timer-vt8500.
Move the system events timer from channel 0 to channel 1 when enough
information is provided by the device tree (i.e. more than one IRQ).
Use channel 0 for the system watchdog

Signed-off-by: Alexey Charkov <alchark@gmail.com>
---
Changes in v2:
- Included the previously reviewed binding change that is directly related
  to this series as the first patch here (thanks Krzysztof)
- Created a separate config symbol for the watchdog function to let users
  build a kernel without forcing watchdog functionality upon them
  (thanks Krzysztof)
- Link to the previous binding submission: https://lore.kernel.org/all/20250506-via_vt8500_timer_binding-v3-1-88450907503f@gmail.com/
- Link to v1: https://lore.kernel.org/r/20250507-vt8500-timer-updates-v1-0-6b76f7f340a6@gmail.com

---
Alexey Charkov (4):
      dt-bindings: timer: via,vt8500-timer: Convert to YAML
      clocksource/drivers/timer-vt8500: Add defines for magic constants
      clocksource/drivers/timer-vt8500: Add watchdog functionality
      ARM: dts: vt8500: list all four timer interrupts

 .../devicetree/bindings/timer/via,vt8500-timer.txt |  15 ---
 .../bindings/timer/via,vt8500-timer.yaml           |  51 +++++++++
 MAINTAINERS                                        |   1 +
 arch/arm/boot/dts/vt8500/vt8500.dtsi               |   2 +-
 arch/arm/boot/dts/vt8500/wm8505.dtsi               |   2 +-
 arch/arm/boot/dts/vt8500/wm8650.dtsi               |   2 +-
 arch/arm/boot/dts/vt8500/wm8750.dtsi               |   2 +-
 arch/arm/boot/dts/vt8500/wm8850.dtsi               |   2 +-
 drivers/clocksource/Kconfig                        |  11 ++
 drivers/clocksource/timer-vt8500.c                 | 118 ++++++++++++++++-----
 10 files changed, 162 insertions(+), 44 deletions(-)
---
base-commit: 0a00723f4c2d0b273edd0737f236f103164a08eb
change-id: 20250506-vt8500-timer-updates-44a0d22cd720

Best regards,
-- 
Alexey Charkov <alchark@gmail.com>

[PATCH v2 1/4] dt-bindings: timer: via,vt8500-timer: Convert to YAML

[Alexey Charkov]

Rewrite the textual description for the VIA/WonderMedia timer
as YAML schema.

The IP can generate up to four interrupts from four respective match
registers, so reflect that in the schema.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Alexey Charkov <alchark@gmail.com>
---
 .../devicetree/bindings/timer/via,vt8500-timer.txt | 15 -------
 .../bindings/timer/via,vt8500-timer.yaml           | 51 ++++++++++++++++++++++
 MAINTAINERS                                        |  1 +
 3 files changed, 52 insertions(+), 15 deletions(-)

diff --git a/Documentation/devicetree/bindings/timer/via,vt8500-timer.txt b/Documentation/devicetree/bindings/timer/via,vt8500-timer.txt
deleted file mode 100644
index 901c73f0d8ef05fb54d517b807d04f80eef2e736..0000000000000000000000000000000000000000
--- a/Documentation/devicetree/bindings/timer/via,vt8500-timer.txt
+++ /dev/null
@@ -1,15 +0,0 @@
-VIA/Wondermedia VT8500 Timer
------------------------------------------------------
-
-Required properties:
-- compatible : "via,vt8500-timer"
-- reg : Should contain 1 register ranges(address and length)
-- interrupts : interrupt for the timer
-
-Example:
-
-	timer@d8130100 {
-		compatible = "via,vt8500-timer";
-		reg = <0xd8130100 0x28>;
-		interrupts = <36>;
-	};
diff --git a/Documentation/devicetree/bindings/timer/via,vt8500-timer.yaml b/Documentation/devicetree/bindings/timer/via,vt8500-timer.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..e748149948f3140d4a158f800b91e70bf9c4f042
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/via,vt8500-timer.yaml
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/via,vt8500-timer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: VIA/Wondermedia VT8500 Timer
+
+description:
+  This is the timer block that is a standalone part of the system power
+  management controller on VIA/WonderMedia SoCs (VIA VT8500 and alike).
+  The hardware has a single 32-bit counter running at 3 MHz and four match
+  registers, each of which is associated with a dedicated match interrupt,
+  and the first of which can also serve as the system watchdog (if the
+  watchdog function is enabled, it will reset the system upon match instead
+  of triggering its respective interrupt)
+
+maintainers:
+  - Alexey Charkov <alchark@gmail.com>
+
+properties:
+  compatible:
+    const: via,vt8500-timer
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    minItems: 1
+    items:
+      - description: Channel 0 match. Note that if the watchdog function
+          is enabled, this interrupt will not fire and the system will
+          reboot instead once the counter reaches match register 0 value
+      - description: Channel 1 match
+      - description: Channel 2 match
+      - description: Channel 3 match
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    timer@d8130100 {
+        compatible = "via,vt8500-timer";
+        reg = <0xd8130100 0x28>;
+        interrupts = <36>;
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 16037aaa770fc35efb45fc26555afaa5102e2640..5c38a60eb3bddc47106509d6cc6450ae93e50191 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3467,6 +3467,7 @@ F:	Documentation/devicetree/bindings/hwinfo/via,vt8500-scc-id.yaml
 F:	Documentation/devicetree/bindings/i2c/i2c-wmt.txt
 F:	Documentation/devicetree/bindings/interrupt-controller/via,vt8500-intc.yaml
 F:	Documentation/devicetree/bindings/pwm/via,vt8500-pwm.yaml
+F:	Documentation/devicetree/bindings/timer/via,vt8500-timer.yaml
 F:	arch/arm/boot/dts/vt8500/
 F:	arch/arm/mach-vt8500/
 F:	drivers/clocksource/timer-vt8500.c

-- 
2.49.0

[PATCH v2 2/4] clocksource/drivers/timer-vt8500: Add defines for magic constants

[Alexey Charkov]

Add defines for all known registers and their bits to make the code more
self-explanatory. While at that, replace _VAL suffixes with more
intuitive _REG suffixes on register offsets.

No functional changes.

Signed-off-by: Alexey Charkov <alchark@gmail.com>
---
 drivers/clocksource/timer-vt8500.c | 65 ++++++++++++++++++++++++--------------
 1 file changed, 42 insertions(+), 23 deletions(-)

diff --git a/drivers/clocksource/timer-vt8500.c b/drivers/clocksource/timer-vt8500.c
index a469b1b5f97233202bf01298b9f612e07026c20c..9f28f30dcaf83ab4e9c89952175b0d4c75bd6b40 100644
--- a/drivers/clocksource/timer-vt8500.c
+++ b/drivers/clocksource/timer-vt8500.c
@@ -24,15 +24,31 @@
 
 #define VT8500_TIMER_OFFSET	0x0100
 #define VT8500_TIMER_HZ		3000000
-#define TIMER_MATCH_VAL		0x0000
-#define TIMER_COUNT_VAL		0x0010
-#define TIMER_STATUS_VAL	0x0014
-#define TIMER_IER_VAL		0x001c		/* interrupt enable */
-#define TIMER_CTRL_VAL		0x0020
-#define TIMER_AS_VAL		0x0024		/* access status */
-#define TIMER_COUNT_R_ACTIVE	(1 << 5)	/* not ready for read */
-#define TIMER_COUNT_W_ACTIVE	(1 << 4)	/* not ready for write */
-#define TIMER_MATCH_W_ACTIVE	(1 << 0)	/* not ready for write */
+
+#define TIMER_MATCH_REG(x)	(4 * (x))
+#define TIMER_COUNT_REG		0x0010	 /* clocksource counter */
+
+#define TIMER_STATUS_REG	0x0014
+#define TIMER_STATUS_MATCH(x)	BIT((x))
+#define TIMER_STATUS_CLEARALL	(TIMER_STATUS_MATCH(0) | \
+				 TIMER_STATUS_MATCH(1) | \
+				 TIMER_STATUS_MATCH(2) | \
+				 TIMER_STATUS_MATCH(3))
+
+#define TIMER_WATCHDOG_EN_REG	0x0018
+#define TIMER_WD_EN		BIT(0)
+
+#define TIMER_INT_EN_REG	0x001c	 /* interrupt enable */
+#define TIMER_INT_EN_MATCH(x)	BIT((x))
+
+#define TIMER_CTRL_REG		0x0020
+#define TIMER_CTRL_ENABLE	BIT(0)	 /* enable clocksource counter */
+#define TIMER_CTRL_RD_REQ	BIT(1)	 /* request counter read */
+
+#define TIMER_ACC_STS_REG	0x0024	 /* access status */
+#define TIMER_ACC_WR_MATCH(x)	BIT((x)) /* writing Match (x) value */
+#define TIMER_ACC_WR_COUNTER	BIT(4)	 /* writing clocksource counter */
+#define TIMER_ACC_RD_COUNTER	BIT(5)	 /* reading clocksource counter */
 
 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
 
@@ -43,11 +59,12 @@ static void __iomem *regbase;
 static u64 vt8500_timer_read(struct clocksource *cs)
 {
 	int loops = msecs_to_loops(10);
-	writel(3, regbase + TIMER_CTRL_VAL);
-	while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE)
-						&& --loops)
+
+	writel(TIMER_CTRL_ENABLE | TIMER_CTRL_RD_REQ, regbase + TIMER_CTRL_REG);
+	while (readl(regbase + TIMER_ACC_STS_REG) & TIMER_ACC_RD_COUNTER
+	     && --loops)
 		cpu_relax();
-	return readl(regbase + TIMER_COUNT_VAL);
+	return readl(regbase + TIMER_COUNT_REG);
 }
 
 static struct clocksource clocksource = {
@@ -63,23 +80,25 @@ static int vt8500_timer_set_next_event(unsigned long cycles,
 {
 	int loops = msecs_to_loops(10);
 	u64 alarm = clocksource.read(&clocksource) + cycles;
-	while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE)
-						&& --loops)
+
+	while (readl(regbase + TIMER_ACC_STS_REG) & TIMER_ACC_WR_MATCH(0)
+	       && --loops)
 		cpu_relax();
-	writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL);
+	writel((unsigned long)alarm, regbase + TIMER_MATCH_REG(0));
 
 	if ((signed)(alarm - clocksource.read(&clocksource)) <= MIN_OSCR_DELTA)
 		return -ETIME;
 
-	writel(1, regbase + TIMER_IER_VAL);
+	writel(TIMER_INT_EN_MATCH(0), regbase + TIMER_INT_EN_REG);
 
 	return 0;
 }
 
 static int vt8500_shutdown(struct clock_event_device *evt)
 {
-	writel(readl(regbase + TIMER_CTRL_VAL) | 1, regbase + TIMER_CTRL_VAL);
-	writel(0, regbase + TIMER_IER_VAL);
+	writel(readl(regbase + TIMER_CTRL_REG) | TIMER_CTRL_ENABLE,
+	       regbase + TIMER_CTRL_REG);
+	writel(0, regbase + TIMER_INT_EN_REG);
 	return 0;
 }
 
@@ -95,7 +114,7 @@ static struct clock_event_device clockevent = {
 static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)
 {
 	struct clock_event_device *evt = dev_id;
-	writel(0xf, regbase + TIMER_STATUS_VAL);
+	writel(TIMER_STATUS_CLEARALL, regbase + TIMER_STATUS_REG);
 	evt->event_handler(evt);
 
 	return IRQ_HANDLED;
@@ -119,9 +138,9 @@ static int __init vt8500_timer_init(struct device_node *np)
 		return -EINVAL;
 	}
 
-	writel(1, regbase + TIMER_CTRL_VAL);
-	writel(0xf, regbase + TIMER_STATUS_VAL);
-	writel(~0, regbase + TIMER_MATCH_VAL);
+	writel(TIMER_CTRL_ENABLE, regbase + TIMER_CTRL_REG);
+	writel(TIMER_STATUS_CLEARALL, regbase + TIMER_STATUS_REG);
+	writel(~0, regbase + TIMER_MATCH_REG(0));
 
 	ret = clocksource_register_hz(&clocksource, VT8500_TIMER_HZ);
 	if (ret) {

-- 
2.49.0

[PATCH v2 3/4] clocksource/drivers/timer-vt8500: Add watchdog functionality

[Alexey Charkov]

VIA/WonderMedia system timer IP can generate a watchdog reset when its
clocksource counter matches the value in the match register 0 and
watchdog function is enabled. For this to work, obvously the clock event
device must use a different match register (1~3) and respective interrupt.

Check if at least two interrupts are provided by the device tree, then use
match register 1 for system clock events and match register 0 for watchdog
respectively.

Signed-off-by: Alexey Charkov <alchark@gmail.com>
---
 drivers/clocksource/Kconfig        | 11 +++++++
 drivers/clocksource/timer-vt8500.c | 61 ++++++++++++++++++++++++++++++++++----
 2 files changed, 67 insertions(+), 5 deletions(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 487c8525996724fbf9c6e9726dabb478d86513b9..8f5e41ff23386d9ecb46b38603dae485db71cfc7 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -181,6 +181,17 @@ config VT8500_TIMER
 	help
 	  Enables support for the VT8500 driver.
 
+config VT8500_TIMER_WATCHDOG
+	bool "Enable VT8500 watchdog functionality"
+	depends on VT8500_TIMER
+	depends on WATCHDOG && WATCHDOG_CORE=y
+	help
+	  VIA/WonderMedia SoCs can use their system timer as a hardware
+	  watchdog, as long as the first timer channel is free from other
+	  uses and respective function is enabled in its registers. To
+	  make use of it, say Y here and ensure that the device tree
+	  lists at least two interrupts for the VT8500 timer device
+
 config NPCM7XX_TIMER
 	bool "NPCM7xx timer driver" if COMPILE_TEST
 	depends on HAS_IOMEM
diff --git a/drivers/clocksource/timer-vt8500.c b/drivers/clocksource/timer-vt8500.c
index 9f28f30dcaf83ab4e9c89952175b0d4c75bd6b40..4128c4f19adc2e02b6df2d0aa2dca4659f62fba7 100644
--- a/drivers/clocksource/timer-vt8500.c
+++ b/drivers/clocksource/timer-vt8500.c
@@ -22,6 +22,8 @@
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 
+#include <linux/watchdog.h>
+
 #define VT8500_TIMER_OFFSET	0x0100
 #define VT8500_TIMER_HZ		3000000
 
@@ -55,6 +57,9 @@
 #define MIN_OSCR_DELTA		16
 
 static void __iomem *regbase;
+static unsigned int sys_timer_ch;	 /* which match register to use
+					  * for the system timer
+					  */
 
 static u64 vt8500_timer_read(struct clocksource *cs)
 {
@@ -81,15 +86,15 @@ static int vt8500_timer_set_next_event(unsigned long cycles,
 	int loops = msecs_to_loops(10);
 	u64 alarm = clocksource.read(&clocksource) + cycles;
 
-	while (readl(regbase + TIMER_ACC_STS_REG) & TIMER_ACC_WR_MATCH(0)
+	while (readl(regbase + TIMER_ACC_STS_REG) & TIMER_ACC_WR_MATCH(sys_timer_ch)
 	       && --loops)
 		cpu_relax();
-	writel((unsigned long)alarm, regbase + TIMER_MATCH_REG(0));
+	writel((unsigned long)alarm, regbase + TIMER_MATCH_REG(sys_timer_ch));
 
 	if ((signed)(alarm - clocksource.read(&clocksource)) <= MIN_OSCR_DELTA)
 		return -ETIME;
 
-	writel(TIMER_INT_EN_MATCH(0), regbase + TIMER_INT_EN_REG);
+	writel(TIMER_INT_EN_MATCH(sys_timer_ch), regbase + TIMER_INT_EN_REG);
 
 	return 0;
 }
@@ -120,6 +125,40 @@ static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static int vt8500_watchdog_start(struct watchdog_device *wdd)
+{
+	u64 cycles = wdd->timeout * VT8500_TIMER_HZ;
+	u64 deadline = clocksource.read(&clocksource) + cycles;
+
+	writel((u32)deadline, regbase + TIMER_MATCH_REG(0));
+	writel(TIMER_WD_EN, regbase + TIMER_WATCHDOG_EN_REG);
+	return 0;
+}
+
+static int vt8500_watchdog_stop(struct watchdog_device *wdd)
+{
+	writel(0, regbase + TIMER_WATCHDOG_EN_REG);
+	return 0;
+}
+
+static const struct watchdog_ops vt8500_watchdog_ops = {
+	.start			= vt8500_watchdog_start,
+	.stop			= vt8500_watchdog_stop,
+};
+
+static const struct watchdog_info vt8500_watchdog_info = {
+	.identity		= "VIA VT8500 watchdog",
+	.options		= WDIOF_MAGICCLOSE |
+				  WDIOF_KEEPALIVEPING |
+				  WDIOF_SETTIMEOUT,
+};
+
+static struct watchdog_device vt8500_watchdog_device = {
+	.ops			= &vt8500_watchdog_ops,
+	.info			= &vt8500_watchdog_info,
+	.max_hw_heartbeat_ms	= -1UL / (VT8500_TIMER_HZ / 1000),
+};
+
 static int __init vt8500_timer_init(struct device_node *np)
 {
 	int timer_irq, ret;
@@ -131,7 +170,9 @@ static int __init vt8500_timer_init(struct device_node *np)
 		return -ENXIO;
 	}
 
-	timer_irq = irq_of_parse_and_map(np, 0);
+	sys_timer_ch = of_irq_count(np) > 1 ? 1 : 0;
+
+	timer_irq = irq_of_parse_and_map(np, sys_timer_ch);
 	if (!timer_irq) {
 		pr_err("%s: Missing irq description in Device Tree\n",
 								__func__);
@@ -140,7 +181,7 @@ static int __init vt8500_timer_init(struct device_node *np)
 
 	writel(TIMER_CTRL_ENABLE, regbase + TIMER_CTRL_REG);
 	writel(TIMER_STATUS_CLEARALL, regbase + TIMER_STATUS_REG);
-	writel(~0, regbase + TIMER_MATCH_REG(0));
+	writel(~0, regbase + TIMER_MATCH_REG(sys_timer_ch));
 
 	ret = clocksource_register_hz(&clocksource, VT8500_TIMER_HZ);
 	if (ret) {
@@ -163,6 +204,16 @@ static int __init vt8500_timer_init(struct device_node *np)
 	clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ,
 					MIN_OSCR_DELTA * 2, 0xf0000000);
 
+	if (!IS_ENABLED(CONFIG_VT8500_TIMER_WATCHDOG))
+		return 0;
+
+	if (!sys_timer_ch) {
+		pr_info("%s: Not enabling watchdog: only one irq was given\n",
+			__func__);
+	} else {
+		watchdog_register_device(&vt8500_watchdog_device);
+	}
+
 	return 0;
 }
 

-- 
2.49.0

[PATCH v2 4/4] ARM: dts: vt8500: list all four timer interrupts

[Alexey Charkov]

VIA/WonderMedia SoC timer can generate up to four interrupts corresponding
to four timer match registers (firing when the 32-bit freerunning clock
source counter matches either of the match registers, respectively).

List all four interrupts in device trees.

This also enables the system event timer to use a match register other
than 0, which can then in turn be used as a system watchdog (watchdog
function is not available on other channels)

Signed-off-by: Alexey Charkov <alchark@gmail.com>
---
 arch/arm/boot/dts/vt8500/vt8500.dtsi | 2 +-
 arch/arm/boot/dts/vt8500/wm8505.dtsi | 2 +-
 arch/arm/boot/dts/vt8500/wm8650.dtsi | 2 +-
 arch/arm/boot/dts/vt8500/wm8750.dtsi | 2 +-
 arch/arm/boot/dts/vt8500/wm8850.dtsi | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm/boot/dts/vt8500/vt8500.dtsi b/arch/arm/boot/dts/vt8500/vt8500.dtsi
index 2ba021585d4889f29777a12473964c29f999f3a0..d1dd37220d41becece5d24fbb19aa71b01723e35 100644
--- a/arch/arm/boot/dts/vt8500/vt8500.dtsi
+++ b/arch/arm/boot/dts/vt8500/vt8500.dtsi
@@ -111,7 +111,7 @@ clkuart3: uart3 {
 		timer@d8130100 {
 			compatible = "via,vt8500-timer";
 			reg = <0xd8130100 0x28>;
-			interrupts = <36>;
+			interrupts = <36>, <37>, <38>, <39>;
 		};
 
 		usb@d8007900 {
diff --git a/arch/arm/boot/dts/vt8500/wm8505.dtsi b/arch/arm/boot/dts/vt8500/wm8505.dtsi
index 99c064c916b2279797f71261ca9306e9dcd4bbd8..2b1819f0c5412648a83cd3eeb495f68d2e4100ef 100644
--- a/arch/arm/boot/dts/vt8500/wm8505.dtsi
+++ b/arch/arm/boot/dts/vt8500/wm8505.dtsi
@@ -209,7 +209,7 @@ clksdhc: sdhc {
 		timer@d8130100 {
 			compatible = "via,vt8500-timer";
 			reg = <0xd8130100 0x28>;
-			interrupts = <36>;
+			interrupts = <36>, <37>, <38>, <39>;
 		};
 
 		usb@d8007100 {
diff --git a/arch/arm/boot/dts/vt8500/wm8650.dtsi b/arch/arm/boot/dts/vt8500/wm8650.dtsi
index 0d6c7bd87f7dcce0eef056d04c38ab1de5d52639..042eec78c085d19fc97d7f0f9721399c0716ff74 100644
--- a/arch/arm/boot/dts/vt8500/wm8650.dtsi
+++ b/arch/arm/boot/dts/vt8500/wm8650.dtsi
@@ -181,7 +181,7 @@ clksdhc: sdhc {
 		timer@d8130100 {
 			compatible = "via,vt8500-timer";
 			reg = <0xd8130100 0x28>;
-			interrupts = <36>;
+			interrupts = <36>, <37>, <38>, <39>;
 		};
 
 		usb@d8007900 {
diff --git a/arch/arm/boot/dts/vt8500/wm8750.dtsi b/arch/arm/boot/dts/vt8500/wm8750.dtsi
index 0158c0ba5dd110957eac38775d3bf3ebd2ab4154..56342aa1d993a43e7ee766f93151c6d456496262 100644
--- a/arch/arm/boot/dts/vt8500/wm8750.dtsi
+++ b/arch/arm/boot/dts/vt8500/wm8750.dtsi
@@ -253,7 +253,7 @@ pwm: pwm@d8220000 {
 		timer@d8130100 {
 			compatible = "via,vt8500-timer";
 			reg = <0xd8130100 0x28>;
-			interrupts = <36>;
+			interrupts = <36>, <37>, <38>, <39>;
 		};
 
 		usb@d8007900 {
diff --git a/arch/arm/boot/dts/vt8500/wm8850.dtsi b/arch/arm/boot/dts/vt8500/wm8850.dtsi
index c4bfb4d30aad0358b39cbf30edf0c63e32167bbd..03e72f28d31b1cfdcfa71ede93b8943971bae4e3 100644
--- a/arch/arm/boot/dts/vt8500/wm8850.dtsi
+++ b/arch/arm/boot/dts/vt8500/wm8850.dtsi
@@ -240,7 +240,7 @@ pwm: pwm@d8220000 {
 		timer@d8130100 {
 			compatible = "via,vt8500-timer";
 			reg = <0xd8130100 0x28>;
-			interrupts = <36>;
+			interrupts = <36>, <37>, <38>, <39>;
 		};
 
 		usb@d8007900 {

-- 
2.49.0

Re: (subset) [PATCH v2 4/4] ARM: dts: vt8500: list all four timer interrupts

[Krzysztof Kozlowski]

On Wed, 07 May 2025 10:58:33 +0400, Alexey Charkov wrote:
> VIA/WonderMedia SoC timer can generate up to four interrupts corresponding
> to four timer match registers (firing when the 32-bit freerunning clock
> source counter matches either of the match registers, respectively).
> 
> List all four interrupts in device trees.
> 
> This also enables the system event timer to use a match register other
> than 0, which can then in turn be used as a system watchdog (watchdog
> function is not available on other channels)
> 
> [...]

Applied, thanks!

[4/4] ARM: dts: vt8500: list all four timer interrupts
      https://git.kernel.org/krzk/linux-dt/c/e58afb3e1f365badd69aad6f0d53a2c66a63f689

Best regards,
-- 
Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Re: [PATCH v2 3/4] clocksource/drivers/timer-vt8500: Add watchdog functionality

[Daniel Lezcano]

On Wed, May 07, 2025 at 10:58:32AM +0400, Alexey Charkov wrote:
> VIA/WonderMedia system timer IP can generate a watchdog reset when its
> clocksource counter matches the value in the match register 0 and
> watchdog function is enabled. For this to work, obvously the clock event
> device must use a different match register (1~3) and respective interrupt.
> 
> Check if at least two interrupts are provided by the device tree, then use
> match register 1 for system clock events and match register 0 for watchdog
> respectively.

This code falls under the watchdog umbrella not in the clocksource. It
is better to find a way to make the timer and the watchdog separated.

The timer-gxp.c is dynamically allocating a watchdog platform device
with the shared pointer to the timer counter. IMO, it is a good
example to split this up.

> Signed-off-by: Alexey Charkov <alchark@gmail.com>
> ---
>  drivers/clocksource/Kconfig        | 11 +++++++
>  drivers/clocksource/timer-vt8500.c | 61 ++++++++++++++++++++++++++++++++++----
>  2 files changed, 67 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 487c8525996724fbf9c6e9726dabb478d86513b9..8f5e41ff23386d9ecb46b38603dae485db71cfc7 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -181,6 +181,17 @@ config VT8500_TIMER
>  	help
>  	  Enables support for the VT8500 driver.
>  
> +config VT8500_TIMER_WATCHDOG
> +	bool "Enable VT8500 watchdog functionality"
> +	depends on VT8500_TIMER
> +	depends on WATCHDOG && WATCHDOG_CORE=y

if WATCHDOG_CORE=y then WATCHDOG=y because the first one can be
enabled only if the second one is enabled.

[ ... ]

-- 

 <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog

Re: [PATCH v2 3/4] clocksource/drivers/timer-vt8500: Add watchdog functionality

[Alexey Charkov]

On Tue, May 13, 2025 at 5:40 PM Daniel Lezcano
<daniel.lezcano@linaro.org> wrote:
>
> On Wed, May 07, 2025 at 10:58:32AM +0400, Alexey Charkov wrote:
> > VIA/WonderMedia system timer IP can generate a watchdog reset when its
> > clocksource counter matches the value in the match register 0 and
> > watchdog function is enabled. For this to work, obvously the clock event
> > device must use a different match register (1~3) and respective interrupt.
> >
> > Check if at least two interrupts are provided by the device tree, then use
> > match register 1 for system clock events and match register 0 for watchdog
> > respectively.
>
> This code falls under the watchdog umbrella not in the clocksource. It
> is better to find a way to make the timer and the watchdog separated.
>
> The timer-gxp.c is dynamically allocating a watchdog platform device
> with the shared pointer to the timer counter. IMO, it is a good
> example to split this up.

Thanks for the pointer Daniel!

I guess in this case I'll need to pass the pointer to a full
clocksource read function as platform data for the watchdog, as it's a
bit more messy here than timer-gxp.c in that this hardware cannot do
an atomic MMIO read of the counter and needs a synchronization request
to be issued and cleared before reading the value.

The clocksource code will then only instantiate a platform device for
the watchdog when it can ensure that nothing uses the first match
register.

> > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > ---
> >  drivers/clocksource/Kconfig        | 11 +++++++
> >  drivers/clocksource/timer-vt8500.c | 61 ++++++++++++++++++++++++++++++++++----
> >  2 files changed, 67 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> > index 487c8525996724fbf9c6e9726dabb478d86513b9..8f5e41ff23386d9ecb46b38603dae485db71cfc7 100644
> > --- a/drivers/clocksource/Kconfig
> > +++ b/drivers/clocksource/Kconfig
> > @@ -181,6 +181,17 @@ config VT8500_TIMER
> >       help
> >         Enables support for the VT8500 driver.
> >
> > +config VT8500_TIMER_WATCHDOG
> > +     bool "Enable VT8500 watchdog functionality"
> > +     depends on VT8500_TIMER
> > +     depends on WATCHDOG && WATCHDOG_CORE=y
>
> if WATCHDOG_CORE=y then WATCHDOG=y because the first one can be
> enabled only if the second one is enabled.

Noted, thanks. Will replace it with just WATCHDOG_CORE=y in the next
version. In fact, if the watchdog functionality becomes a separate
platform driver then it could also potentially be built as a module,
so "=y" might also go.

Best regards,
Alexey