[PATCH v4 0/3] BPi M2 Zero poweroff support via new regulator-poweroff driver

[PATCH v4 0/3] BPi M2 Zero poweroff support via new regulator-poweroff driver

[Michael Klein]

Changes in v2:
  - rename DT node

Changes in v3:
  - add regulator-poweroff driver
  - use regulator-poweroff driver instead of gpio-poweroff

Changes in v4:
  - hardcode poweroff timeout to 3000ms, not configurable any more
  - remove support for multiple regulators
  - fix Documentation issues

Michael Klein (3):
  power: reset: new driver regulator-poweroff
  Documentation: DT: binding documentation for regulator-poweroff
  ARM: dts: sun8i-h2-plus-bananapi-m2-zero: add poweroff node

 .../power/reset/regulator-poweroff.yaml       | 37 ++++++++
 .../dts/sun8i-h2-plus-bananapi-m2-zero.dts    |  5 ++
 drivers/power/reset/Kconfig                   |  7 ++
 drivers/power/reset/Makefile                  |  1 +
 drivers/power/reset/regulator-poweroff.c      | 86 +++++++++++++++++++
 5 files changed, 136 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power/reset/regulator-poweroff.yaml
 create mode 100644 drivers/power/reset/regulator-poweroff.c

-- 
2.29.2

[PATCH v4 1/3] power: reset: new driver regulator-poweroff

[Michael Klein]

This driver registers a pm_power_off function to disable a set of
regulators defined in the devicetree to turn off the board.

Signed-off-by: Michael Klein <michael@fossekall.de>
---
 drivers/power/reset/Kconfig              |  7 ++
 drivers/power/reset/Makefile             |  1 +
 drivers/power/reset/regulator-poweroff.c | 86 ++++++++++++++++++++++++
 3 files changed, 94 insertions(+)
 create mode 100644 drivers/power/reset/regulator-poweroff.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index d55b3727e00e..b22c4fdb2561 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -177,6 +177,13 @@ config POWER_RESET_QNAP
 
 	  Say Y if you have a QNAP NAS.
 
+config POWER_RESET_REGULATOR
+	bool "Regulator subsystem power-off driver"
+	depends on OF && REGULATOR
+	help
+	  This driver supports turning off your board by disabling a
+	  power regulator defined in the devicetree.
+
 config POWER_RESET_RESTART
 	bool "Restart power-off driver"
 	help
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index c51eceba9ea3..9dc49d3a57ff 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_POWER_RESET_OCELOT_RESET) += ocelot-reset.o
 obj-$(CONFIG_POWER_RESET_PIIX4_POWEROFF) += piix4-poweroff.o
 obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
 obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
+obj-$(CONFIG_POWER_RESET_REGULATOR) += regulator-poweroff.o
 obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o
 obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o
 obj-$(CONFIG_POWER_RESET_VERSATILE) += arm-versatile-reboot.o
diff --git a/drivers/power/reset/regulator-poweroff.c b/drivers/power/reset/regulator-poweroff.c
new file mode 100644
index 000000000000..c67136cd7b90
--- /dev/null
+++ b/drivers/power/reset/regulator-poweroff.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Force-disables a regulator to power down a device
+ *
+ * Michael Klein <michael@fossekall.de>
+ *
+ * Copyright (C) 2020 Michael Klein
+ *
+ * Based on the gpio-poweroff driver.
+ */
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/regulator/consumer.h>
+
+#define TIMEOUT_MS 3000
+
+/*
+ * Hold configuration here, cannot be more than one instance of the driver
+ * since pm_power_off itself is global.
+ */
+static struct regulator *poweroff_regulator;
+
+static void regulator_poweroff_do_poweroff(void)
+{
+	if (poweroff_regulator && regulator_is_enabled(poweroff_regulator))
+		regulator_force_disable(poweroff_regulator);
+
+	/* give it some time */
+	mdelay(TIMEOUT_MS);
+
+	WARN_ON(1);
+}
+
+static int regulator_poweroff_probe(struct platform_device *pdev)
+{
+	struct regulator *regulator;
+
+	/* If a pm_power_off function has already been added, leave it alone */
+	if (pm_power_off != NULL) {
+		dev_err(&pdev->dev,
+			"%s: pm_power_off function already registered\n",
+			__func__);
+		return -EBUSY;
+	}
+
+	regulator = devm_regulator_get(&pdev->dev, "power");
+	if (IS_ERR(regulator))
+		return PTR_ERR(regulator);
+
+	poweroff_regulator = regulator;
+
+	pm_power_off = &regulator_poweroff_do_poweroff;
+	return 0;
+}
+
+static int regulator_poweroff_remove(__maybe_unused struct platform_device *pdev)
+{
+	if (pm_power_off == &regulator_poweroff_do_poweroff)
+		pm_power_off = NULL;
+
+	return 0;
+}
+
+static const struct of_device_id of_regulator_poweroff_match[] = {
+	{ .compatible = "regulator-poweroff", },
+	{},
+};
+
+static struct platform_driver regulator_poweroff_driver = {
+	.probe = regulator_poweroff_probe,
+	.remove = regulator_poweroff_remove,
+	.driver = {
+		.name = "poweroff-regulator",
+		.of_match_table = of_regulator_poweroff_match,
+	},
+};
+
+module_platform_driver(regulator_poweroff_driver);
+
+MODULE_AUTHOR("Michael Klein <michael@fossekall.de>");
+MODULE_DESCRIPTION("Regulator poweroff driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:poweroff-regulator");
-- 
2.29.2

[PATCH v4 2/3] Documentation: DT: binding documentation for regulator-poweroff

[Michael Klein]

Add devicetree binding documentation for regulator-poweroff driver.

Signed-off-by: Michael Klein <michael@fossekall.de>
---
 .../power/reset/regulator-poweroff.yaml       | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power/reset/regulator-poweroff.yaml

diff --git a/Documentation/devicetree/bindings/power/reset/regulator-poweroff.yaml b/Documentation/devicetree/bindings/power/reset/regulator-poweroff.yaml
new file mode 100644
index 000000000000..c74ac247ab70
--- /dev/null
+++ b/Documentation/devicetree/bindings/power/reset/regulator-poweroff.yaml
@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/power/reset/regulator-poweroff.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Force-disable power regulator to turn the power off.
+
+maintainers:
+  - Michael Klein <michael@fossekall.de>
+
+description: |
+  When the power-off handler is called, a power regulator is disabled by
+  calling regulator_force_disable(). If the power is still on and the
+  CPU still running after a 3000ms delay, a warning is emitted.
+
+properties:
+  compatible:
+    const: "regulator-poweroff"
+
+  power-supply:
+    description:
+      regulator to disable on power-down
+
+required:
+  - compatible
+  - power-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    regulator-poweroff {
+        compatible = "regulator-poweroff";
+        power-supply = <&reg_vcc1v2>;
+    };
+...
-- 
2.29.2

Re: [PATCH v4 2/3] Documentation: DT: binding documentation for regulator-poweroff

[Rob Herring]

On Wed, 09 Dec 2020 22:02:20 +0100, Michael Klein wrote:
> Add devicetree binding documentation for regulator-poweroff driver.
> 
> Signed-off-by: Michael Klein <michael@fossekall.de>
> ---
>  .../power/reset/regulator-poweroff.yaml       | 37 +++++++++++++++++++
>  1 file changed, 37 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/power/reset/regulator-poweroff.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>

[PATCH v4 3/3] ARM: dts: sun8i-h2-plus-bananapi-m2-zero: add poweroff node

[Michael Klein]

Add add devicetree information for the regulator-poweroff driver.

Signed-off-by: Michael Klein <michael@fossekall.de>
---
This patch depends on the regulator names added in

 arch/arm/boot/dts/sun8i-h2-plus-bananapi-m2-zero.dts | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm/boot/dts/sun8i-h2-plus-bananapi-m2-zero.dts b/arch/arm/boot/dts/sun8i-h2-plus-bananapi-m2-zero.dts
index b43028f9e6df..e7370a049ce2 100644
--- a/arch/arm/boot/dts/sun8i-h2-plus-bananapi-m2-zero.dts
+++ b/arch/arm/boot/dts/sun8i-h2-plus-bananapi-m2-zero.dts
@@ -86,6 +86,11 @@ reg_vcc1v2: vcc1v2 {
 		vin-supply = <&reg_vcc5v0>;
 	};
 
+	poweroff {
+		compatible = "regulator-poweroff";
+		power-supply = <&reg_vcc1v2>;
+	};
+
 	wifi_pwrseq: wifi_pwrseq {
 		compatible = "mmc-pwrseq-simple";
 		reset-gpios = <&r_pio 0 7 GPIO_ACTIVE_LOW>; /* PL7 */
-- 
2.29.2