samples: dac: move HW config to /zephyr,user

Require board overlays to configure the sample in the /zephyr,user
node, and access the device with DEVICE_DT_GET instead of
device_get_binding(). Update the documentation and move existing board
configuration to overlays.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

samples/drivers/dac/README.rst

@@ -13,6 +13,10 @@ Building and Running
 
 The DAC output is defined in the board's devicetree and pinmux file.
 
+The board's :ref:`/zephyr,user <dt-zephyr-user>` node must have ``dac``,
+``dac-channel-id``, and ``dac-resolution`` properties set. See the predefined
+overlays in :zephyr_file:`samples/drivers/dac/boards` for examples.
+
 Building and Running for ST Nucleo L073RZ
 =========================================
 The sample can be built and executed for the

samples/drivers/dac/boards/arduino_zero.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac0>;
+		dac-channel-id = <0>;
+		dac-resolution = <10>;
+	};
+};

samples/drivers/dac/boards/frdm_k22f.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac0>;
+		dac-channel-id = <0>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/frdm_k64f.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac0>;
+		dac-channel-id = <0>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/nucleo_f091rc.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac1>;
+		dac-channel-id = <1>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/nucleo_f429zi.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac1>;
+		dac-channel-id = <1>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/nucleo_f767zi.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac1>;
+		dac-channel-id = <1>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/nucleo_g071rb.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac1>;
+		dac-channel-id = <1>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/nucleo_g431rb.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac1>;
+		dac-channel-id = <1>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/nucleo_l073rz.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac1>;
+		dac-channel-id = <1>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/nucleo_l152re.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac1>;
+		dac-channel-id = <1>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/ronoth_lodev.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac1>;
+		dac-channel-id = <1>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/boards/twr_ke18f.overlay

@@ -0,0 +1,7 @@
+/ {
+	zephyr,user {
+		dac = <&dac0>;
+		dac-channel-id = <0>;
+		dac-resolution = <12>;
+	};
+};

samples/drivers/dac/src/main.c

@@ -8,37 +8,23 @@
 #include <sys/printk.h>
 #include <drivers/dac.h>
 
-#if defined(CONFIG_BOARD_NUCLEO_F091RC) || \
+#define ZEPHYR_USER_NODE DT_PATH(zephyr_user)
-	defined(CONFIG_BOARD_NUCLEO_G071RB) || \
+
-	defined(CONFIG_BOARD_NUCLEO_G431RB) || \
+#if (DT_NODE_HAS_PROP(ZEPHYR_USER_NODE, dac) && \
-	defined(CONFIG_BOARD_NUCLEO_L073RZ) || \
+	DT_NODE_HAS_PROP(ZEPHYR_USER_NODE, dac_channel_id) && \
-	defined(CONFIG_BOARD_NUCLEO_L152RE) || \
+	DT_NODE_HAS_PROP(ZEPHYR_USER_NODE, dac_resolution))
-	defined(CONFIG_BOARD_NUCLEO_F429ZI) || \
+#define DAC_NODE DT_PHANDLE(ZEPHYR_USER_NODE, dac)
-	defined(CONFIG_BOARD_NUCLEO_F767ZI) || \
+#define DAC_CHANNEL_ID DT_PROP(ZEPHYR_USER_NODE, dac_channel_id)
-	defined(CONFIG_BOARD_RONOTH_LODEV)
+#define DAC_RESOLUTION DT_PROP(ZEPHYR_USER_NODE, dac_resolution)
-#define DAC_DEVICE_NAME		DT_LABEL(DT_NODELABEL(dac1))
-#define DAC_CHANNEL_ID		1
-#define DAC_RESOLUTION		12
-#elif defined(CONFIG_BOARD_TWR_KE18F)
-#define DAC_DEVICE_NAME		DT_LABEL(DT_NODELABEL(dac0))
-#define DAC_CHANNEL_ID		0
-#define DAC_RESOLUTION		12
-#elif defined(CONFIG_BOARD_FRDM_K64F)
-#define DAC_DEVICE_NAME		DT_LABEL(DT_NODELABEL(dac0))
-#define DAC_CHANNEL_ID		0
-#define DAC_RESOLUTION		12
-#elif defined(CONFIG_BOARD_FRDM_K22F)
-#define DAC_DEVICE_NAME		DT_LABEL(DT_NODELABEL(dac0))
-#define DAC_CHANNEL_ID		0
-#define DAC_RESOLUTION		12
-#elif defined(CONFIG_BOARD_ARDUINO_ZERO)
-#define DAC_DEVICE_NAME		DT_LABEL(DT_NODELABEL(dac0))
-#define DAC_CHANNEL_ID		0
-#define DAC_RESOLUTION		10
 #else
-#error "Unsupported board."
+#error "Unsupported board: see README and check /zephyr,user node"
+#define DAC_NODE DT_INVALID_NODE
+#define DAC_CHANNEL_ID 0
+#define DAC_RESOLUTION 0
 #endif
 
+static const struct device *dac_dev = DEVICE_DT_GET(DAC_NODE);
+
 static const struct dac_channel_cfg dac_ch_cfg = {
 	.channel_id  = DAC_CHANNEL_ID,
 	.resolution  = DAC_RESOLUTION
@@ -46,10 +32,8 @@ static const struct dac_channel_cfg dac_ch_cfg = {
 
 void main(void)
 {
-	const struct device *dac_dev = device_get_binding(DAC_DEVICE_NAME);
+	if (!device_is_ready(dac_dev)) {
-
+		printk("DAC device %s is not ready\n", dac_dev->name);
-	if (!dac_dev) {
-		printk("Cannot get DAC device\n");
 		return;
 	}