emul: Use DEVICE_DT_GET instead of DT_LABEL

DT nodes aren't guaranteed to define a label property. But emulated bus
controllers currently make use of this property to dispatch to the
associated emulator.

Have emulated bus controllers use DEVICE_DT_GET(node_id) to dispatch to
right target peripheral emulator. This also change makes emul_get_binding
and device_get_binding synonymous in behavior with respect to their
parameters.

This also strictly enforces a 1:1 correspondence between invocations of
DEVICE_DT_DEFINE and EMUL_DEFINE.

Signed-off-by: Aaron Massey <aaronmassey@google.com>

drivers/espi/espi_emul.c

@@ -225,7 +225,7 @@ static struct emul_espi_driver_api emul_espi_driver_api = {
 
 #define EMUL_LINK_AND_COMMA(node_id)                                                               \
 	{                                                                                          \
-		.label = DT_LABEL(node_id),                                                        \
+		.dev = DEVICE_DT_GET(node_id),                                                     \
 	},
 
 #define ESPI_EMUL_INIT(n)                                                                          \

drivers/i2c/i2c_emul.c

@@ -139,7 +139,7 @@ static struct i2c_driver_api i2c_emul_api = {
 
 #define EMUL_LINK_AND_COMMA(node_id)                                                               \
 	{                                                                                          \
-		.label = DT_LABEL(node_id),                                                        \
+		.dev = DEVICE_DT_GET(node_id),                                                     \
 	},
 
 #define I2C_EMUL_INIT(n)                                                                           \

drivers/spi/spi_emul.c

@@ -114,7 +114,7 @@ static struct spi_driver_api spi_emul_api = {
 
 #define EMUL_LINK_AND_COMMA(node_id)                                                               \
 	{                                                                                          \
-		.label = DT_LABEL(node_id),                                                        \
+		.dev = DEVICE_DT_GET(node_id),                                                     \
 	},
 
 #define SPI_EMUL_INIT(n)                                                                           \

include/zephyr/drivers/emul.h

@@ -37,11 +37,9 @@ enum emul_bus_type {
 
 /**
  * Structure uniquely identifying a device to be emulated
- *
- * Currently this uses the device node label, but that will go away by 2.5.
  */
 struct emul_link_for_bus {
-	const char *label;
+	const struct device *dev;
 };
 
 /** List of emulators attached to a bus */
@@ -69,7 +67,7 @@ struct emul {
 	/** function used to initialise the emulator state */
 	emul_init_t init;
 	/** handle to the device for which this provides low-level emulation */
-	const char *dev_label;
+	const struct device *dev;
 	/** Emulator-specific configuration data */
 	const void *cfg;
 	/** Emulator-specific data */
@@ -113,7 +111,8 @@ extern const struct emul __emul_list_end[];
  *
  * @param init_ptr function to call to initialise the emulator (see emul_init
  *	typedef)
- * @param node_id Node ID of the driver to emulate (e.g. DT_DRV_INST(n))
+ * @param node_id Node ID of the driver to emulate (e.g. DT_DRV_INST(n)); the node_id *MUST* have a
+ * corresponding DEVICE_DT_DEFINE().
  * @param cfg_ptr emulator-specific configuration data
  * @param data_ptr emulator-specific data
  * @param bus_api emulator-specific bus api
@@ -127,7 +126,7 @@ extern const struct emul __emul_list_end[];
 	static struct emul EMUL_REG_NAME(node_id) __attribute__((__section__(".emulators")))       \
 	__used = {                                                                                 \
 		.init = (init_ptr),                                                                \
-		.dev_label = DT_LABEL(node_id),                                                    \
+		.dev = DEVICE_DT_GET(node_id),                                                     \
 		.cfg = (cfg_ptr),                                                                  \
 		.data = (data_ptr),                                                                \
 		.bus_type = Z_EMUL_BUS(node_id, EMUL_BUS_TYPE_I2C, EMUL_BUS_TYPE_ESPI,             \

subsys/emul/emul.c

@@ -18,7 +18,7 @@ const struct emul *emul_get_binding(const char *name)
 	const struct emul *emul_it;
 
 	for (emul_it = __emul_list_start; emul_it < __emul_list_end; emul_it++) {
-		if (strcmp(emul_it->dev_label, name) == 0) {
+		if (strcmp(emul_it->dev->name, name) == 0) {
 			return emul_it;
 		}
 	}
@@ -39,9 +39,9 @@ int emul_init_for_bus(const struct device *dev)
 
 	LOG_INF("Registering %d emulator(s) for %s", cfg->num_children, dev->name);
 	for (elp = cfg->children; elp < end; elp++) {
-		const struct emul *emul = emul_get_binding(elp->label);
+		const struct emul *emul = emul_get_binding(elp->dev->name);
 
-		__ASSERT(emul, "Cannot find emulator for '%s'", elp->label);
+		__ASSERT(emul, "Cannot find emulator for '%s'", elp->dev->name);
 
 		switch (emul->bus_type) {
 		case EMUL_BUS_TYPE_I2C:
@@ -58,33 +58,33 @@ int emul_init_for_bus(const struct device *dev)
 
 		if (rc != 0) {
 			LOG_WRN("Init %s emulator failed: %d",
-				 elp->label, rc);
+				 elp->dev->name, rc);
 		}
 
 		switch (emul->bus_type) {
 #ifdef CONFIG_I2C_EMUL
 		case EMUL_BUS_TYPE_I2C:
-			rc = i2c_emul_register(dev, emul->dev_label, emul->bus.i2c);
+			rc = i2c_emul_register(dev, emul->dev->name, emul->bus.i2c);
 			break;
 #endif /* CONFIG_I2C_EMUL */
 #ifdef CONFIG_ESPI_EMUL
 		case EMUL_BUS_TYPE_ESPI:
-			rc = espi_emul_register(dev, emul->dev_label, emul->bus.espi);
+			rc = espi_emul_register(dev, emul->dev->name, emul->bus.espi);
 			break;
 #endif /* CONFIG_ESPI_EMUL */
 #ifdef CONFIG_SPI_EMUL
 		case EMUL_BUS_TYPE_SPI:
-			rc = spi_emul_register(dev, emul->dev_label, emul->bus.spi);
+			rc = spi_emul_register(dev, emul->dev->name, emul->bus.spi);
 			break;
 #endif /* CONFIG_SPI_EMUL */
 		default:
 			rc = -EINVAL;
 			LOG_WRN("Found no emulated bus enabled to register emulator %s",
-				elp->label);
+				elp->dev->name);
 		}
 
 		if (rc != 0) {
-			LOG_WRN("Failed to register emulator for %s: %d", elp->label, rc);
+			LOG_WRN("Failed to register emulator for %s: %d", elp->dev->name, rc);
 		}
 	}
 

tests/drivers/espi/src/stub_espi_emul_host.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2022 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/device.h>
+#include <zephyr/devicetree.h>
+
+#define DT_DRV_COMPAT zephyr_espi_emul_espi_host
+
+/* Stub out an espi host device struct to use espi_host emulator. */
+static int emul_espi_host_init_stub(const struct device *dev)
+{
+	ARG_UNUSED(dev);
+
+	return 0;
+}
+
+struct emul_espi_host_stub_dev_data {
+	/* Stub */
+};
+struct emul_espi_host_stub_dev_config {
+	/* Stub */
+};
+struct emul_espi_host_stub_dev_api {
+	/* Stub */
+};
+
+/* Since this is only stub, allocate the structs once. */
+static struct emul_espi_host_stub_dev_data stub_host_data;
+static struct emul_espi_host_stub_dev_config stub_host_config;
+static struct emul_espi_host_stub_dev_api stub_host_api;
+
+#define EMUL_ESPI_HOST_DEVICE_STUB(n)                                                              \
+	DEVICE_DT_INST_DEFINE(n, &emul_espi_host_init_stub, NULL, &stub_host_data,                 \
+			      &stub_host_config, POST_KERNEL, CONFIG_ESPI_INIT_PRIORITY,           \
+			      &stub_host_api)
+
+DT_INST_FOREACH_STATUS_OKAY(EMUL_ESPI_HOST_DEVICE_STUB);