tracing: Move to DTS for uart device

Move from using Kconfig TRACING_BACKEND_UART_NAME to a devicetree
chosen property ("zephyr,tracing-uart").  This is similar to a number
of other functions like "zephyr,shell-uart" or "zephyr,bt-uart".

Signed-off-by: Kumar Gala <galak@kernel.org>

doc/build/dts/api/api.rst

@@ -432,6 +432,8 @@ device.
    * - zephyr,sram
      - A node whose ``reg`` sets the base address and size of SRAM memory
        available to the Zephyr image, used during linking
+   * - zephyr,tracing-uart
+     - Sets UART device used by tracing subsystem
    * - zephyr,uart-mcumgr
      - UART used for :ref:`device_mgmt`
    * - zephyr,uart-pipe

samples/subsys/tracing/boards/qemu_x86.overlay

@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+
+/ {
+       chosen {
+               zephyr,tracing-uart = &uart1;
+       };
+};

samples/subsys/tracing/boards/qemu_x86_64.overlay

@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+
+/ {
+       chosen {
+               zephyr,tracing-uart = &uart1;
+       };
+};

samples/subsys/tracing/prj_uart.conf

@@ -3,5 +3,3 @@ CONFIG_TRACING=y
 CONFIG_TRACING_TEST=y
 CONFIG_TRACING_BACKEND_UART=y
 CONFIG_TRACING_BUFFER_SIZE=4096
-
-CONFIG_TRACING_BACKEND_UART_NAME="UART_1"

samples/subsys/tracing/prj_uart_ctf.conf

@@ -2,4 +2,3 @@ CONFIG_TRACING=y
 CONFIG_TRACING_CTF=y
 CONFIG_TRACING_BACKEND_UART=y
 CONFIG_TRACING_BUFFER_SIZE=4096
-CONFIG_TRACING_BACKEND_UART_NAME="UART_1"

subsys/tracing/Kconfig

@@ -170,16 +170,6 @@ config RAM_TRACING_BUFFER_SIZE
 	  Size of the RAM trace buffer. Trace will be discarded if the
 	  length is exceeded.
 
-
-config TRACING_BACKEND_UART_NAME
-	string "Device Name of UART Device for UART backend"
-	default "$(dt_chosen_label,$(DT_CHOSEN_Z_CONSOLE))" if HAS_DTS
-	default "UART_0"
-	depends on TRACING_BACKEND_UART
-	help
-	  This option specifies the name of UART device to be used for
-	  tracing backend.
-
 config TRACING_USB_MPS
 	int "USB backend max packet size"
 	default 64

subsys/tracing/tracing_backend_uart.c

@@ -76,9 +76,8 @@ static void tracing_backend_uart_output(
 
 static void tracing_backend_uart_init(void)
 {
-	tracing_uart_dev =
-		device_get_binding(CONFIG_TRACING_BACKEND_UART_NAME);
-	__ASSERT(tracing_uart_dev, "uart backend binding failed");
+	tracing_uart_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_tracing_uart));
+	__ASSERT(device_is_ready(tracing_uart_dev), "uart backend is not ready");
 
 #ifdef CONFIG_TRACING_HANDLE_HOST_CMD
 	uart_irq_rx_disable(tracing_uart_dev);

tests/subsys/tracing/tracing_api/boards/qemu_x86.overlay

@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+
+/ {
+       chosen {
+               zephyr,tracing-uart = &uart0;
+       };
+};