[PATCH v2 0/3] Apple M1 watchdog timer

[PATCH v2 0/3] Apple M1 watchdog timer

[Mark Kettenis]

This series adds a driver for the watchdog timer found on Apple's
M1 SoC and replaces the reset_cpu() function in the board file
with sysreset.  The driver is based on the Linux binding proposed
in [1].

[1] https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20211113094732.73889-1-sven@svenpeter.dev/


ChangeLog:

v2: - Adjust delay and add comment
    - Explain dropped device tree node in commit message

Mark Kettenis (3):
  watchdog: Add a driver for the Apple watchdog
  arm: dts: apple: Add watchdog timer node
  arm: apple: Use watchdog timer for system reset

 MAINTAINERS                  |   1 +
 arch/arm/Kconfig             |   3 +
 arch/arm/dts/t8103.dtsi      |  13 ++--
 arch/arm/mach-apple/board.c  |  24 --------
 drivers/watchdog/Kconfig     |   9 +++
 drivers/watchdog/Makefile    |   1 +
 drivers/watchdog/apple_wdt.c | 115 +++++++++++++++++++++++++++++++++++
 7 files changed, 137 insertions(+), 29 deletions(-)
 create mode 100644 drivers/watchdog/apple_wdt.c

-- 
2.34.1

[PATCH v2 1/3] watchdog: Add a driver for the Apple watchdog

[Mark Kettenis]

This driver supports the watchdog timer found on Apple's M1 SoC.
On systems that use these SoC, the watchdog timer is the primary
way to reboot the system.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-on: Apple M1 Macbook
Tested-by: Simon Glass <sjg@chromium.org>
---

ChangeLog:

v2: - Adjust delay and add comment


 MAINTAINERS                  |   1 +
 drivers/watchdog/Kconfig     |   9 +++
 drivers/watchdog/Makefile    |   1 +
 drivers/watchdog/apple_wdt.c | 115 +++++++++++++++++++++++++++++++++++
 4 files changed, 126 insertions(+)
 create mode 100644 drivers/watchdog/apple_wdt.c

diff --git a/MAINTAINERS b/MAINTAINERS
index f4bd3d79e2..6ae81c5659 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -116,6 +116,7 @@ F:	arch/arm/mach-apple/
 F:	configs/apple_m1_defconfig
 F:	drivers/iommu/apple_dart.c
 F:	drivers/pinctrl/pinctrl-apple.c
+F:	drivers/watchdog/apple_wdt.c
 F:	include/configs/apple.h
 
 ARM
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 1177f17fd8..cabac29053 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -81,6 +81,15 @@ config WDT
 	  What exactly happens when the timer expires is up to a particular
 	  device/driver.
 
+config WDT_APPLE
+	bool "Apple watchdog timer support"
+	depends on WDT
+	default y if ARCH_APPLE
+	help
+	  Enable support for the watchdog timer on Apple SoCs.
+	  The watchdog will perform a full SoC reset resulting in a
+	  reboot of the entire system.
+
 config WDT_ARMADA_37XX
 	bool "Marvell Armada 37xx watchdog timer support"
 	depends on WDT && ARMADA_3700
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index fa7ce583ce..6d2b3822c0 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_DESIGNWARE_WATCHDOG) += designware_wdt.o
 obj-$(CONFIG_ULP_WATCHDOG) += ulp_wdog.o
 obj-$(CONFIG_$(SPL_TPL_)WDT) += wdt-uclass.o
 obj-$(CONFIG_WDT_SANDBOX) += sandbox_wdt.o
+obj-$(CONFIG_WDT_APPLE) += apple_wdt.o
 obj-$(CONFIG_WDT_ARMADA_37XX) += armada-37xx-wdt.o
 obj-$(CONFIG_WDT_ASPEED) += ast_wdt.o
 obj-$(CONFIG_WDT_AST2600) += ast2600_wdt.o
diff --git a/drivers/watchdog/apple_wdt.c b/drivers/watchdog/apple_wdt.c
new file mode 100644
index 0000000000..c7307f41cb
--- /dev/null
+++ b/drivers/watchdog/apple_wdt.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2021 Mark Kettenis <kettenis@openbsd.org>
+ */
+
+#include <clk.h>
+#include <dm.h>
+#include <wdt.h>
+#include <asm/io.h>
+#include <linux/delay.h>
+
+#define APPLE_WDT_CUR_TIME		0x10
+#define APPLE_WDT_BARK_TIME		0x14
+#define APPLE_WDT_CTRL			0x1c
+#define  APPLE_WDT_CTRL_RESET_EN	BIT(2)
+
+struct apple_wdt_priv {
+	void *base;
+	ulong clk_rate;
+};
+
+static int apple_wdt_reset(struct udevice *dev)
+{
+	struct apple_wdt_priv *priv = dev_get_priv(dev);
+
+	writel(0, priv->base + APPLE_WDT_CUR_TIME);
+
+	return 0;
+}
+
+static int apple_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
+{
+	struct apple_wdt_priv *priv = dev_get_priv(dev);
+	u64 timeout;
+
+	timeout = (timeout_ms * priv->clk_rate) / 1000;
+	if (timeout > U32_MAX)
+		return -EINVAL;
+
+	writel(0, priv->base + APPLE_WDT_CUR_TIME);
+	writel(timeout, priv->base + APPLE_WDT_BARK_TIME);
+	writel(APPLE_WDT_CTRL_RESET_EN, priv->base + APPLE_WDT_CTRL);
+
+	return 0;
+}
+
+static int apple_wdt_stop(struct udevice *dev)
+{
+	struct apple_wdt_priv *priv = dev_get_priv(dev);
+
+	writel(0, priv->base + APPLE_WDT_CTRL);
+
+	return 0;
+}
+
+static int apple_wdt_expire_now(struct udevice *dev, ulong flags)
+{
+	int ret;
+
+	ret = apple_wdt_start(dev, 0, flags);
+	if (ret)
+		return ret;
+
+	/*
+	 * It can take up to 25ms until the SoC actually resets, so
+	 * wait 50ms just to be sure.
+	 */
+	mdelay(50);
+
+	return 0;
+}
+
+static const struct wdt_ops apple_wdt_ops = {
+	.reset = apple_wdt_reset,
+	.start = apple_wdt_start,
+	.stop = apple_wdt_stop,
+	.expire_now = apple_wdt_expire_now,
+};
+
+static const struct udevice_id apple_wdt_ids[] = {
+	{ .compatible = "apple,wdt" },
+	{ /* sentinel */ }
+};
+
+static int apple_wdt_probe(struct udevice *dev)
+{
+	struct apple_wdt_priv *priv = dev_get_priv(dev);
+	struct clk clk;
+	int ret;
+
+	priv->base = dev_read_addr_ptr(dev);
+	if (!priv->base)
+		return -EINVAL;
+
+	ret = clk_get_by_index(dev, 0, &clk);
+	if (ret)
+		return ret;
+
+	ret = clk_enable(&clk);
+	if (ret)
+		return ret;
+
+	priv->clk_rate = clk_get_rate(&clk);
+
+	return 0;
+}
+
+U_BOOT_DRIVER(apple_wdt) = {
+	.name = "apple_wdt",
+	.id = UCLASS_WDT,
+	.of_match = apple_wdt_ids,
+	.priv_auto = sizeof(struct apple_wdt_priv),
+	.probe = apple_wdt_probe,
+	.ops = &apple_wdt_ops,
+};
-- 
2.34.1

[PATCH v2 2/3] arm: dts: apple: Add watchdog timer node

[Mark Kettenis]

Add a node for the watchdog timer based on the proposed Linux
device tree bindings.

Remove the old reboot node which was a watchdog timert node in
disguise using a preliminary device tree binding.

Signed-off-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-on: Apple M1 Macbook
Tested-by: Simon Glass <sjg@chromium.org>
---

ChangeLog:

v2: - Explain dropped device tree node in commit message


 arch/arm/dts/t8103.dtsi | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/arm/dts/t8103.dtsi b/arch/arm/dts/t8103.dtsi
index 7d9cb272f9..03d8436fec 100644
--- a/arch/arm/dts/t8103.dtsi
+++ b/arch/arm/dts/t8103.dtsi
@@ -328,6 +328,14 @@
 				     <AIC_IRQ 336 IRQ_TYPE_LEVEL_HIGH>;
 		};
 
+		wdt: watchdog@23d2b0000 {
+			compatible = "apple,t8103-wdt", "apple,wdt";
+			reg = <0x2 0x3d2b0000 0x0 0x4000>;
+			clocks = <&clkref>;
+			interrupt-parent = <&aic>;
+			interrupts = <AIC_IRQ 338 IRQ_TYPE_LEVEL_HIGH>;
+		};
+
 		pinctrl_smc: pinctrl@23e820000 {
 			compatible = "apple,t8103-pinctrl", "apple,pinctrl";
 			reg = <0x2 0x3e820000 0x0 0x4000>;
@@ -529,11 +537,6 @@
 			status = "disabled";
 		};
 
-		reboot@23d2b0000 {
-			compatible = "apple,reboot-v0";
-			reg = <0x2 0x3d2b0000 0x0 0x4000>;
-		};
-
 		spi@23510c000 {
 			compatible = "apple,t8103-spi", "apple,spi";
 			reg = <0x2 0x3510c000 0x0 0x4000>;
-- 
2.34.1

[PATCH v2 3/3] arm: apple: Use watchdog timer for system reset

[Mark Kettenis]

Rely on the new watchdog timer driver and the sysreset uclass to
reset the system.  This gets rid of hard-coded addresses and
should work on systems based on the new M1 Pro and M1 Max SoCs
as well.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-on: Apple M1 Macbook
Tested-by: Simon Glass <sjg@chromium.org>
---
 arch/arm/Kconfig            |  3 +++
 arch/arm/mach-apple/board.c | 24 ------------------------
 2 files changed, 3 insertions(+), 24 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7264d72bde..78c6b2e92d 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -942,6 +942,9 @@ config ARCH_APPLE
 	select OF_CONTROL
 	select PINCTRL
 	select POSITION_INDEPENDENT
+	select SYSRESET
+	select SYSRESET_WATCHDOG
+	select SYSRESET_WATCHDOG_AUTO
 	select USB
 	imply CMD_DM
 	imply CMD_GPT
diff --git a/arch/arm/mach-apple/board.c b/arch/arm/mach-apple/board.c
index 0bfbc473ec..b7e8d212f1 100644
--- a/arch/arm/mach-apple/board.c
+++ b/arch/arm/mach-apple/board.c
@@ -119,30 +119,6 @@ int dram_init_banksize(void)
 	return fdtdec_setup_memory_banksize();
 }
 
-#define APPLE_WDT_BASE		0x23d2b0000ULL
-
-#define APPLE_WDT_SYS_CTL_ENABLE	BIT(2)
-
-typedef struct apple_wdt {
-	u32	reserved0[3];
-	u32	chip_ctl;
-	u32	sys_tmr;
-	u32	sys_cmp;
-	u32	reserved1;
-	u32	sys_ctl;
-} apple_wdt_t;
-
-void reset_cpu(void)
-{
-	apple_wdt_t *wdt = (apple_wdt_t *)APPLE_WDT_BASE;
-
-	writel(0, &wdt->sys_cmp);
-	writel(APPLE_WDT_SYS_CTL_ENABLE, &wdt->sys_ctl);
-
-	while(1)
-		wfi();
-}
-
 extern long fw_dtb_pointer;
 
 void *board_fdt_blob_setup(int *err)
-- 
2.34.1

Re: [PATCH v2 0/3] Apple M1 watchdog timer

[Stefan Roese]

On 1/12/22 19:55, Mark Kettenis wrote:
> This series adds a driver for the watchdog timer found on Apple's
> M1 SoC and replaces the reset_cpu() function in the board file
> with sysreset.  The driver is based on the Linux binding proposed
> in [1].
> 
> [1] https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20211113094732.73889-1-sven@svenpeter.dev/
> 
> 
> ChangeLog:
> 
> v2: - Adjust delay and add comment
>      - Explain dropped device tree node in commit message
> 
> Mark Kettenis (3):
>    watchdog: Add a driver for the Apple watchdog
>    arm: dts: apple: Add watchdog timer node
>    arm: apple: Use watchdog timer for system reset
> 
>   MAINTAINERS                  |   1 +
>   arch/arm/Kconfig             |   3 +
>   arch/arm/dts/t8103.dtsi      |  13 ++--
>   arch/arm/mach-apple/board.c  |  24 --------
>   drivers/watchdog/Kconfig     |   9 +++
>   drivers/watchdog/Makefile    |   1 +
>   drivers/watchdog/apple_wdt.c | 115 +++++++++++++++++++++++++++++++++++
>   7 files changed, 137 insertions(+), 29 deletions(-)
>   create mode 100644 drivers/watchdog/apple_wdt.c
> 

Applied to u-boot-marvell/master

Thanks,
Stefan