drivers: stepper: Add stepper driver for allegro a4979

Adding a stepper driver implementation for allegro a4979
microstepping programmable stepper motor driver.
The implemenation was tested using the drv8424/api testsuite.

Signed-off-by: Verena Schweinstetter <[email protected]>

Author: Verena Schweinstetter

drivers/stepper/CMakeLists.txt

@@ -5,6 +5,7 @@ zephyr_syscall_header(${ZEPHYR_BASE}/include/zephyr/drivers/stepper.h)
 
 # zephyr-keep-sorted-start
 add_subdirectory_ifdef(CONFIG_STEPPER_ADI_TMC adi_tmc)
+add_subdirectory_ifdef(CONFIG_STEPPER_ALLEGRO allegro)
 add_subdirectory_ifdef(CONFIG_STEPPER_TI ti)
 add_subdirectory_ifdef(CONFIG_STEP_DIR_STEPPER step_dir)
 # zephyr-keep-sorted-stop

drivers/stepper/Kconfig

@@ -34,6 +34,7 @@ comment "Stepper Drivers"
 rsource "Kconfig.fake"
 rsource "Kconfig.gpio"
 rsource "adi_tmc/Kconfig"
+rsource "allegro/Kconfig"
 rsource "ti/Kconfig"
 # zephyr-keep-sorted-stop
 

drivers/stepper/allegro/CMakeLists.txt

@@ -0,0 +1,7 @@
+# SPDX-FileCopyrightText: Copyright (c) 2025 Carl Zeiss Meditec AG
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_property(ALLOW_EMPTY TRUE)
+
+zephyr_library_sources_ifdef(CONFIG_A4979_STEPPER a4979.c)

drivers/stepper/allegro/Kconfig

@@ -0,0 +1,19 @@
+# SPDX-FileCopyrightText: Copyright (c) 2025 Carl Zeiss Meditec AG
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig STEPPER_ALLEGRO
+	bool "Allegro Stepper Controller"
+	depends on STEPPER
+	default y
+	help
+	  Enable allegro stepper controller
+
+if STEPPER_ALLEGRO
+
+comment "Allegro Stepper Drivers"
+
+# zephyr-keep-sorted-start
+rsource "Kconfig.a4979"
+# zephyr-keep-sorted-stop
+
+endif # STEPPER_ALLEGRO

drivers/stepper/allegro/Kconfig.a4979

@@ -0,0 +1,10 @@
+# SPDX-FileCopyrightText: Copyright (c) 2025 Carl Zeiss Meditec AG
+# SPDX-License-Identifier: Apache-2.0
+
+config A4979_STEPPER
+	bool "Activate allegro A4979 stepper driver"
+	default y
+	depends on DT_HAS_ALLEGRO_A4979_ENABLED
+	select STEP_DIR_STEPPER
+	help
+	  Microstepping motor driver for stepper motors.

drivers/stepper/allegro/a4979.c

@@ -0,0 +1,278 @@
+/*
+ * SPDX-FileCopyrightText: Copyright (c) 2025 Carl Zeiss Meditec AG
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT allegro_a4979
+
+#include <zephyr/kernel.h>
+#include <zephyr/drivers/stepper.h>
+#include <zephyr/drivers/gpio.h>
+#include "../step_dir/step_dir_stepper_common.h"
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(a4979, CONFIG_STEPPER_LOG_LEVEL);
+
+struct a4979_config {
+	const struct step_dir_stepper_common_config common;
+	const struct gpio_dt_spec en_pin;
+	const struct gpio_dt_spec reset_pin;
+	const struct gpio_dt_spec m0_pin;
+	const struct gpio_dt_spec m1_pin;
+};
+
+struct a4979_data {
+	const struct step_dir_stepper_common_data common;
+	enum stepper_micro_step_resolution micro_step_res;
+	bool enabled;
+};
+
+STEP_DIR_STEPPER_STRUCT_CHECK(struct a4979_config, struct a4979_data);
+
+static int a4979_set_microstep_pin(const struct device *dev, const struct gpio_dt_spec *pin,
+				   int value)
+{
+	int ret;
+
+	/* Reset microstep pin as it may have been disconnected. */
+	ret = gpio_pin_configure_dt(pin, GPIO_OUTPUT_INACTIVE);
+	if (ret != 0) {
+		LOG_ERR("Failed to configure microstep pin (error: %d)", ret);
+		return ret;
+	}
+
+	ret = gpio_pin_set_dt(pin, value);
+	if (ret != 0) {
+		LOG_ERR("Failed to set microstep pin (error: %d)", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int a4979_stepper_enable(const struct device *dev, bool enable)
+{
+	int ret;
+	const struct a4979_config *config = dev->config;
+	struct a4979_data *data = dev->data;
+	bool has_enable_pin = config->en_pin.port != NULL;
+
+	/* Check availability of enable pin, as it might be hardwired. */
+	if (!has_enable_pin) {
+		LOG_ERR("%s: Enable pin undefined.", dev->name);
+		return -ENOTSUP;
+	}
+
+	ret = gpio_pin_set_dt(&config->en_pin, enable);
+	if (ret != 0) {
+		LOG_ERR("%s: Failed to set en_pin (error: %d)", dev->name, ret);
+		return ret;
+	}
+
+	data->enabled = enable;
+	if (!enable) {
+		config->common.timing_source->stop(dev);
+	}
+
+	return 0;
+}
+
+static int a4979_stepper_set_micro_step_res(const struct device *dev,
+					    const enum stepper_micro_step_resolution micro_step_res)
+{
+	const struct a4979_config *config = dev->config;
+	struct a4979_data *data = dev->data;
+	int ret;
+
+	uint8_t m0_value = 0;
+	uint8_t m1_value = 0;
+
+	switch (micro_step_res) {
+	case STEPPER_MICRO_STEP_1:
+		m0_value = 0;
+		m1_value = 0;
+		break;
+	case STEPPER_MICRO_STEP_2:
+		m0_value = 1;
+		m1_value = 0;
+		break;
+	case STEPPER_MICRO_STEP_4:
+		m0_value = 0;
+		m1_value = 1;
+	case STEPPER_MICRO_STEP_16:
+		m0_value = 1;
+		m1_value = 1;
+		break;
+	default:
+		LOG_ERR("Unsupported micro step resolution %d", micro_step_res);
+		return -ENOTSUP;
+	}
+
+	ret = a4979_set_microstep_pin(dev, &config->m0_pin, m0_value);
+	if (ret != 0) {
+		return ret;
+	}
+	ret = a4979_set_microstep_pin(dev, &config->m1_pin, m1_value);
+	if (ret != 0) {
+		return ret;
+	}
+
+	data->micro_step_res = micro_step_res;
+	return 0;
+}
+
+static int a4979_stepper_get_micro_step_res(const struct device *dev,
+					    enum stepper_micro_step_resolution *micro_step_res)
+{
+	struct a4979_data *data = dev->data;
+
+	*micro_step_res = data->micro_step_res;
+	return 0;
+}
+
+static int a4979_move_to(const struct device *dev, int32_t target)
+{
+	struct a4979_data *data = dev->data;
+
+	if (!data->enabled) {
+		LOG_ERR("Failed to move to target position, device is not enabled");
+		return -ECANCELED;
+	}
+
+	return step_dir_stepper_common_move_to(dev, target);
+}
+
+static int a4979_stepper_move_by(const struct device *dev, const int32_t micro_steps)
+{
+	struct a4979_data *data = dev->data;
+
+	if (!data->enabled) {
+		LOG_ERR("Failed to move by delta, device is not enabled");
+		return -ECANCELED;
+	}
+
+	return step_dir_stepper_common_move_by(dev, micro_steps);
+}
+
+static int a4979_run(const struct device *dev, enum stepper_direction direction)
+{
+	struct a4979_data *data = dev->data;
+
+	if (!data->enabled) {
+		LOG_ERR("Failed to run stepper, device is not enabled");
+		return -ECANCELED;
+	}
+
+	return step_dir_stepper_common_run(dev, direction);
+}
+
+static int a4979_init(const struct device *dev)
+{
+	const struct a4979_config *config = dev->config;
+	struct a4979_data *data = dev->data;
+	int ret;
+
+	bool has_enable_pin = config->en_pin.port != NULL;
+	bool has_reset_pin = config->reset_pin.port != NULL;
+
+	LOG_DBG("Initializing %s gpios", dev->name);
+
+	/* Configure reset pin if it is available */
+	if (has_reset_pin) {
+		if (!gpio_is_ready_dt(&config->reset_pin)) {
+			LOG_ERR("Enable Pin is not ready");
+			return -ENODEV;
+		}
+
+		ret = gpio_pin_configure_dt(&config->reset_pin, GPIO_OUTPUT_ACTIVE);
+		if (ret != 0) {
+			LOG_ERR("%s: Failed to configure reset_pin (error: %d)", dev->name, ret);
+			return ret;
+		}
+	}
+
+	/* Configure enable pin if it is available */
+	if (has_enable_pin) {
+		if (!gpio_is_ready_dt(&config->en_pin)) {
+			LOG_ERR("Enable Pin is not ready");
+			return -ENODEV;
+		}
+
+		ret = gpio_pin_configure_dt(&config->en_pin, GPIO_OUTPUT_INACTIVE);
+		if (ret != 0) {
+			LOG_ERR("%s: Failed to configure en_pin (error: %d)", dev->name, ret);
+			return ret;
+		}
+	}
+
+	/* Configure microstep pin 0 */
+	if (!gpio_is_ready_dt(&config->m0_pin)) {
+		LOG_ERR("m0 Pin is not ready");
+		return -ENODEV;
+	}
+	ret = gpio_pin_configure_dt(&config->m0_pin, GPIO_OUTPUT_INACTIVE);
+	if (ret != 0) {
+		LOG_ERR("%s: Failed to configure m0_pin (error: %d)", dev->name, ret);
+		return ret;
+	}
+
+	/* Configure microstep pin 1 */
+	if (!gpio_is_ready_dt(&config->m1_pin)) {
+		LOG_ERR("m1 Pin is not ready");
+		return -ENODEV;
+	}
+	ret = gpio_pin_configure_dt(&config->m1_pin, GPIO_OUTPUT_INACTIVE);
+	if (ret != 0) {
+		LOG_ERR("%s: Failed to configure m1_pin (error: %d)", dev->name, ret);
+		return ret;
+	}
+
+	ret = a4979_stepper_set_micro_step_res(dev, data->micro_step_res);
+	if (ret != 0) {
+		LOG_ERR("Failed to set micro step resolution: %d", ret);
+		return ret;
+	}
+
+	ret = step_dir_stepper_common_init(dev);
+	if (ret != 0) {
+		LOG_ERR("Failed to initialize common stepper data: %d", ret);
+		return ret;
+	}
+	gpio_pin_set_dt(&config->common.step_pin, 0);
+
+	return 0;
+}
+
+static DEVICE_API(stepper, a4979_stepper_api) = {
+	.enable = a4979_stepper_enable,
+	.move_by = a4979_stepper_move_by,
+	.move_to = a4979_move_to,
+	.is_moving = step_dir_stepper_common_is_moving,
+	.set_reference_position = step_dir_stepper_common_set_reference_position,
+	.get_actual_position = step_dir_stepper_common_get_actual_position,
+	.set_microstep_interval = step_dir_stepper_common_set_microstep_interval,
+	.run = a4979_run,
+	.set_micro_step_res = a4979_stepper_set_micro_step_res,
+	.get_micro_step_res = a4979_stepper_get_micro_step_res,
+	.set_event_callback = step_dir_stepper_common_set_event_callback,
+};
+
+#define A4979_DEVICE(inst)                                                                         \
+                                                                                                   \
+	static const struct a4979_config a4979_config_##inst = {                                   \
+		.common = STEP_DIR_STEPPER_DT_INST_COMMON_CONFIG_INIT(inst),                       \
+		.en_pin = GPIO_DT_SPEC_INST_GET_OR(inst, en_gpios, {0}),                           \
+		.reset_pin = GPIO_DT_SPEC_INST_GET_OR(inst, reset_gpios, {0}),                     \
+		.m0_pin = GPIO_DT_SPEC_INST_GET(inst, m0_gpios),                                   \
+		.m1_pin = GPIO_DT_SPEC_INST_GET(inst, m1_gpios),                                   \
+	};                                                                                         \
+                                                                                                   \
+	static struct a4979_data a4979_data_##inst = {                                             \
+		.common = STEP_DIR_STEPPER_DT_INST_COMMON_DATA_INIT(inst),                         \
+		.micro_step_res = DT_INST_PROP(inst, micro_step_res),                              \
+	};                                                                                         \
+                                                                                                   \
+	DEVICE_DT_INST_DEFINE(inst, a4979_init, NULL, &a4979_data_##inst, &a4979_config_##inst,    \
+			      POST_KERNEL, CONFIG_STEPPER_INIT_PRIORITY, &a4979_stepper_api);
+
+DT_INST_FOREACH_STATUS_OKAY(A4979_DEVICE)

dts/bindings/stepper/allegro/allegro,a4979.yml

@@ -0,0 +1,49 @@
+# SPDX-FileCopyrightText: Copyright (c) 2025 Carl Zeiss Meditec AG
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  Allegro A4979 microstepping stepper motor driver.
+  A4979 is a flexible microstepping motor driver with built-in translator for easy operation.
+  It is designed to operate bipolar stepper motors in full-, half-, quarter-, and sixteenth-step
+  modes.
+
+  Example:
+  a4979: a4979 {
+      status = "okay";
+      compatible = "allegro,a4979";
+      micro-step-res = <2>;
+      reset-gpios = <&gpiod 10 GPIO_ACTIVE_HIGH>;
+      dir-gpios = <&gpiod 14 GPIO_ACTIVE_HIGH>;
+      step-gpios = <&gpiod 15 GPIO_ACTIVE_HIGH>;
+      en-gpios = <&gpiod 11 GPIO_ACTIVE_HIGH>;
+      m0-gpios = <&gpiod 13 0>;
+      m1-gpios = <&gpiod 12 0>;
+      counter = <&counter5>;
+  };
+
+compatible: "allegro,a4979"
+
+include:
+  - name: stepper-controller.yaml
+    property-allowlist:
+      - micro-step-res
+      - step-gpios
+      - dir-gpios
+      - en-gpios
+      - counter
+
+properties:
+  m0-gpios:
+    required: true
+    type: phandle-array
+    description: Microstep configuration pin 0.
+
+  m1-gpios:
+    required: true
+    type: phandle-array
+    description: Microstep configuration pin 1.
+
+  reset-gpios:
+    type: phandle-array
+    required: true
+    description: Reset pin