drivers: power_domain: gpio controlled domain

Initial implementation of a simple GPIO controlled power domain.
It exposes no API of its own, all functionality is contained inside
the runtime power management callbacks.

Signed-off-by: Jordan Yates <jordan.yates@data61.csiro.au>

drivers/CMakeLists.txt

@@ -46,6 +46,7 @@ add_subdirectory_ifdef(CONFIG_REGULATOR regulator)
 add_subdirectory_ifdef(CONFIG_MEMC memc)
 add_subdirectory_ifdef(CONFIG_VIRTUALIZATION virtualization)
 add_subdirectory_ifdef(CONFIG_PM_CPU_OPS pm_cpu_ops)
+add_subdirectory_ifdef(CONFIG_POWER_DOMAIN power_domain)
 
 add_subdirectory_ifdef(CONFIG_FLASH_HAS_DRIVER_ENABLED flash)
 add_subdirectory_ifdef(CONFIG_SERIAL_HAS_DRIVER serial)

drivers/Kconfig

@@ -129,4 +129,6 @@ source "drivers/mbox/Kconfig"
 
 source "drivers/mm/Kconfig"
 
+source "drivers/power_domain/Kconfig"
+
 endmenu

drivers/power_domain/CMakeLists.txt

@@ -0,0 +1,6 @@
+# Copyright (c) 2022, CSIRO
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+
+zephyr_library_sources_ifdef(CONFIG_POWER_DOMAIN_GPIO power_domain_gpio.c)

drivers/power_domain/Kconfig

@@ -0,0 +1,15 @@
+# Copyright (c) 2022, CSIRO.
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig POWER_DOMAIN
+	bool "Power domain drivers"
+	help
+	  Include drivers for power domains in system config
+
+if POWER_DOMAIN
+
+config POWER_DOMAIN_GPIO
+	bool "GPIO controlled power domain"
+	depends on GPIO
+
+endif

drivers/power_domain/power_domain_gpio.c

@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2022, Commonwealth Scientific and Industrial Research
+ * Organisation (CSIRO) ABN 41 687 119 230.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT power_domain_gpio
+
+#include <kernel.h>
+#include <drivers/gpio.h>
+#include <pm/device.h>
+#include <pm/device_runtime.h>
+
+#include <logging/log.h>
+LOG_MODULE_REGISTER(power_domain_gpio, LOG_LEVEL_INF);
+
+struct pd_gpio_config {
+	struct gpio_dt_spec enable;
+	uint32_t startup_delay_us;
+	uint32_t off_on_delay_us;
+};
+
+struct pd_gpio_data {
+	k_timeout_t last_boot;
+};
+
+const char *actions[] = {
+	[PM_DEVICE_ACTION_RESUME] = "RESUME",
+	[PM_DEVICE_ACTION_SUSPEND] = "SUSPEND",
+	[PM_DEVICE_ACTION_TURN_ON] = "TURN ON",
+	[PM_DEVICE_ACTION_TURN_OFF] = "TURN OFF"
+};
+
+
+static int pd_gpio_pm_action(const struct device *dev,
+			     enum pm_device_action action)
+{
+	const struct pd_gpio_config *cfg = dev->config;
+	int rc = 0;
+
+	switch (action) {
+	case PM_DEVICE_ACTION_RESUME:
+		/* Switch power on */
+		gpio_pin_set_dt(&cfg->enable, 1);
+		LOG_DBG("%s is now ON", dev->name);
+		/* Notify supported devices they are now powered */
+		pm_device_children_action_run(dev, PM_DEVICE_ACTION_TURN_ON, NULL);
+		break;
+	case PM_DEVICE_ACTION_SUSPEND:
+		/* Notify supported devices power is going down */
+		pm_device_children_action_run(dev, PM_DEVICE_ACTION_TURN_OFF, NULL);
+		/* Switch power off */
+		gpio_pin_set_dt(&cfg->enable, 0);
+		LOG_DBG("%s is now OFF and powered", dev->name);
+		break;
+	case PM_DEVICE_ACTION_TURN_ON:
+		/* Actively control the enable pin now that the device is powered */
+		gpio_pin_configure_dt(&cfg->enable, GPIO_OUTPUT_INACTIVE);
+		LOG_DBG("%s is OFF and powered", dev->name);
+		break;
+	case PM_DEVICE_ACTION_TURN_OFF:
+		/* Let the enable pin float while device is not powered */
+		gpio_pin_configure_dt(&cfg->enable, GPIO_DISCONNECTED);
+		LOG_DBG("%s is OFF and not powered", dev->name);
+		break;
+	default:
+		rc = -ENOTSUP;
+	}
+
+	return rc;
+}
+
+static int pd_gpio_init(const struct device *dev)
+{
+	const struct pd_gpio_config *cfg = dev->config;
+	int rc;
+
+	if (!device_is_ready(cfg->enable.port)) {
+		LOG_ERR("GPIO port %s is not ready", cfg->enable.port->name);
+		return -ENODEV;
+	}
+
+	if (pm_device_on_power_domain(dev)) {
+		/* Device is unpowered */
+		pm_device_runtime_init_off(dev);
+		rc = gpio_pin_configure_dt(&cfg->enable, GPIO_DISCONNECTED);
+	} else {
+		pm_device_runtime_init_suspended(dev);
+		rc = gpio_pin_configure_dt(&cfg->enable, GPIO_OUTPUT_INACTIVE);
+	}
+
+	return rc;
+}
+
+#define POWER_DOMAIN_DEVICE(id)						   \
+	static const struct pd_gpio_config pd_gpio_##id##_cfg = {	   \
+		.enable = GPIO_DT_SPEC_INST_GET(id, enable_gpios),	   \
+		.startup_delay_us = DT_INST_PROP(id, startup_delay_us),	   \
+		.off_on_delay_us = DT_INST_PROP(id, off_on_delay_us),	   \
+	};								   \
+	static struct pd_gpio_data pd_gpio_##id##_data;			   \
+	PM_DEVICE_DT_INST_DEFINE(id, pd_gpio_pm_action);		   \
+	DEVICE_DT_INST_DEFINE(id, pd_gpio_init, PM_DEVICE_DT_INST_GET(id), \
+			      &pd_gpio_##id##_data, &pd_gpio_##id##_cfg,   \
+			      POST_KERNEL, 75,				   \
+			      NULL);
+
+DT_INST_FOREACH_STATUS_OKAY(POWER_DOMAIN_DEVICE)

dts/bindings/power-domain/power-domain-gpio.yaml

@@ -0,0 +1,32 @@
+# Copyright (c) 2022, CSIRO
+# SPDX-License-Identifier: Apache-2.0
+
+description: Simple GPIO controlled power domain
+
+compatible: "power-domain-gpio"
+
+include: power-domain.yaml
+
+properties:
+  enable-gpios:
+    type: phandle-array
+    required: true
+    description: |
+      GPIO to use to enable/disable the regulator.
+
+      Unlike the gpio property in the Linux bindings this array must
+      provide the GPIO polarity and open-drain status in the phandle
+      selector.  The Linux enable-active-high and gpio-open-drain
+      properties are not valid for Zephyr devicetree files.
+
+  startup-delay-us:
+    type: int
+    required: false
+    default: 0
+    description: Startup time, in microseconds
+
+  off-on-delay-us:
+    type: int
+    required: false
+    default: 0
+    description: Off delay time, in microseconds