drivers: gpio: add GPIO hog support

Add support for automatically configuring GPIO hogs defined in the
devicetree during system initialization.

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>

drivers/gpio/CMakeLists.txt

@@ -72,3 +72,4 @@ zephyr_library_sources_ifdef(CONFIG_GPIO_RT1718S    gpio_rt1718s.c)
 zephyr_library_sources_ifdef(CONFIG_GPIO_RT1718S    gpio_rt1718s_port.c)
 zephyr_library_sources_ifdef(CONFIG_GPIO_NUMICRO    gpio_numicro.c)
 zephyr_library_sources_ifdef(CONFIG_GPIO_KEYS_ZEPHYR gpio_keys_zephyr.c)
+zephyr_library_sources_ifdef(CONFIG_GPIO_HOGS       gpio_hogs.c)

drivers/gpio/Kconfig

@@ -44,6 +44,21 @@ config GPIO_GET_CONFIG
 	  This option enables the support for getting the current configurations
 	  of GPIOs. The driver must implement it to work.
 
+config GPIO_HOGS
+	bool "Support for GPIO hogs"
+	default $(dt_gpio_hogs_enabled)
+	help
+	  Enable support for GPIO hogs. GPIO hogging is a mechanism for providing
+	  automatic GPIO configuration via devicetree.
+
+config GPIO_HOGS_INIT_PRIORITY
+	int "GPIO hogs init priority"
+	default 41
+	depends on GPIO_HOGS
+	help
+	  GPIO hogs initialization priority. GPIO hogs must be initialized after the
+	  GPIO controller drivers.
+
 source "drivers/gpio/Kconfig.b91"
 
 source "drivers/gpio/Kconfig.dw"

drivers/gpio/gpio_hogs.c

@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2022-2023 Vestas Wind Systems A/S
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/devicetree.h>
+#include <zephyr/drivers/gpio.h>
+#include <zephyr/init.h>
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_REGISTER(gpio_hogs, CONFIG_GPIO_LOG_LEVEL);
+
+struct gpio_hog_dt_spec {
+	gpio_pin_t pin;
+	gpio_flags_t flags;
+};
+
+struct gpio_hogs {
+	const struct device *port;
+	const struct gpio_hog_dt_spec *specs;
+	size_t num_specs;
+};
+
+/* Static initializer for a struct gpio_hog_dt_spec */
+#define GPIO_HOG_DT_SPEC_GET_BY_IDX(node_id, idx)						\
+	{											\
+		.pin = DT_GPIO_HOG_PIN_BY_IDX(node_id, idx),					\
+		.flags = DT_GPIO_HOG_FLAGS_BY_IDX(node_id, idx) |				\
+			 COND_CODE_1(DT_PROP(node_id, input), (GPIO_INPUT),			\
+				     (COND_CODE_1(DT_PROP(node_id, output_low),			\
+						 (GPIO_OUTPUT_INACTIVE),			\
+						 (COND_CODE_1(DT_PROP(node_id, output_high),	\
+							     (GPIO_OUTPUT_ACTIVE), (0)))))),	\
+	}
+
+/* Expands to 1 if node_id is a GPIO controller, 0 otherwise */
+#define GPIO_HOGS_NODE_IS_GPIO_CTLR(node_id)			\
+	DT_PROP_OR(node_id, gpio_controller, 0)
+
+/* Expands to to 1 if node_id is a GPIO hog, empty otherwise */
+#define GPIO_HOGS_NODE_IS_GPIO_HOG(node_id)			\
+	IF_ENABLED(DT_PROP_OR(node_id, gpio_hog, 0), 1)
+
+/* Expands to 1 if GPIO controller node_id has GPIO hog children, 0 otherwise */
+#define GPIO_HOGS_GPIO_CTLR_HAS_HOGS(node_id)			\
+	COND_CODE_0(						\
+		IS_EMPTY(DT_FOREACH_CHILD_STATUS_OKAY(node_id,	\
+			GPIO_HOGS_NODE_IS_GPIO_HOG)),		\
+		(1), (0))
+
+/* Called for GPIO hog indexes */
+#define GPIO_HOGS_INIT_GPIO_HOG_BY_IDX(idx, node_id)		\
+	GPIO_HOG_DT_SPEC_GET_BY_IDX(node_id, idx)
+
+/* Called for GPIO hog dts nodes */
+#define GPIO_HOGS_INIT_GPIO_HOGS(node_id)			\
+	LISTIFY(DT_NUM_GPIO_HOGS(node_id),			\
+		GPIO_HOGS_INIT_GPIO_HOG_BY_IDX, (,), node_id),
+
+/* Called for GPIO controller dts node children */
+#define GPIO_HOGS_COND_INIT_GPIO_HOGS(node_id)			\
+	COND_CODE_0(IS_EMPTY(GPIO_HOGS_NODE_IS_GPIO_HOG(node_id)),	\
+		    (GPIO_HOGS_INIT_GPIO_HOGS(node_id)), ())
+
+/* Called for each GPIO controller dts node which has GPIO hog children */
+#define GPIO_HOGS_INIT_GPIO_CTLR(node_id)				\
+	{								\
+		.port = DEVICE_DT_GET(node_id),				\
+		.specs = (const struct gpio_hog_dt_spec []) {		\
+			DT_FOREACH_CHILD_STATUS_OKAY(node_id,		\
+				GPIO_HOGS_COND_INIT_GPIO_HOGS)		\
+		},							\
+		.num_specs =						\
+			DT_FOREACH_CHILD_STATUS_OKAY_SEP(node_id,	\
+				DT_NUM_GPIO_HOGS, (+)),			\
+	},
+
+/* Called for each GPIO controller dts node */
+#define GPIO_HOGS_COND_INIT_GPIO_CTLR(node_id)			\
+	IF_ENABLED(GPIO_HOGS_GPIO_CTLR_HAS_HOGS(node_id),	\
+		   (GPIO_HOGS_INIT_GPIO_CTLR(node_id)))
+
+/* Called for each dts node */
+#define GPIO_HOGS_COND_INIT(node_id)				\
+	IF_ENABLED(GPIO_HOGS_NODE_IS_GPIO_CTLR(node_id),	\
+		   (GPIO_HOGS_COND_INIT_GPIO_CTLR(node_id)))
+
+static const struct gpio_hogs gpio_hogs[] = {
+	DT_FOREACH_STATUS_OKAY_NODE(GPIO_HOGS_COND_INIT)
+};
+
+static int gpio_hogs_init(const struct device *dev)
+{
+	const struct gpio_hogs *hogs;
+	const struct gpio_hog_dt_spec *spec;
+	int err;
+	int i;
+	int j;
+
+	ARG_UNUSED(dev);
+
+	for (i = 0; i < ARRAY_SIZE(gpio_hogs); i++) {
+		hogs = &gpio_hogs[i];
+
+		if (!device_is_ready(hogs->port)) {
+			LOG_ERR("GPIO port %s not ready", hogs->port->name);
+			return -ENODEV;
+		}
+
+		for (j = 0; j < hogs->num_specs; j++) {
+			spec = &hogs->specs[j];
+
+			err = gpio_pin_configure(hogs->port, spec->pin, spec->flags);
+			if (err < 0) {
+				LOG_ERR("failed to configure GPIO hog for port %s pin %u (err %d)",
+					hogs->port->name, spec->pin, err);
+				return err;
+			}
+		}
+	}
+
+	return 0;
+}
+
+SYS_INIT(gpio_hogs_init, POST_KERNEL, CONFIG_GPIO_HOGS_INIT_PRIORITY);