shell: backends: add SHELL_BACKEND_RTT_BUFFER option

This new configuration option, SHELL_BACKEND_RTT_BUFFER, allows selecting an alternative buffer for the Shell's RTT backend. By default buffer 0 is used, which conflicts with the default logging subsystem RTT backend buffer. This option is the counterpart to the logger's LOG_BACKEND_RTT_BUFFER. Signed-off-by: Maurits Fassaert <[email protected]>
albayenes · Apr 13, 2023 · 6bfb663 · 6bfb663
1 parent 1cb259a
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diff --git a/doc/services/shell/index.rst b/doc/services/shell/index.rst
@@ -623,6 +623,33 @@ This feature is activated by: :kconfig:option:`CONFIG_SHELL_LOG_BACKEND` set to
 	RTT (:kconfig:option:`CONFIG_LOG_BACKEND_RTT`), which are available earlier
 	during system initialization.
 
+RTT Backend Channel Selection
+*****************************
+
+Instead of using the shell as a logger backend, RTT shell backend and RTT log
+backend can also be used simulatenously, but over different channels. By
+separating them, the log can be captured or monitored without shell output or
+the shell may be scripted without log interference. Enabling both the Shell RTT
+backend and the Log RTT backend does not work by default, because both default
+to channel ``0``. There are two options:
+
+1. The Shell buffer can use an alternate channel, for example using
+:kconfig:option:`SHELL_BACKEND_RTT_BUFFER` set to ``1``.
+This allows monitoring the log using `JLinkRTTViewer
+<https://www.segger.com/products/debug-probes/j-link/technology/about-real-time-transfer/#j-link-rtt-viewer>`_
+while a script interfaces over channel 1.
+
+2. The Log buffer can use an alternate channel, for example using
+:kconfig:option:`LOG_BACKEND_RTT_BUFFER` set to ``1``.
+This allows interactive use of the shell through JLinkRTTViewer, while the log
+is written to file.
+
+.. warning::
+	Regardless of the channel selection, the RTT log backend must be explicitly
+	enabled using :kconfig:option:`LOG_BACKEND_RTT` set to ``y``, because it
+	defaults to ``n`` when the Shell RTT backend is also enabled using
+	:kconfig:option:`SHELL_BACKEND_RTT` being set to ``y``.
+
 Usage
 *****
 

diff --git a/subsys/shell/backends/Kconfig.backends b/subsys/shell/backends/Kconfig.backends
@@ -139,6 +139,14 @@ config SHELL_PROMPT_RTT
 	  Displayed prompt name for RTT backend. If prompt is set, the shell will
 	  send two newlines during initialization.
 
+config SHELL_BACKEND_RTT_BUFFER
+	int "Buffer number used for shell input and output."
+	range 0 SEGGER_RTT_MAX_NUM_UP_BUFFERS
+	default 0
+	help
+	  Select index of up-buffer used for shell output, by default it uses
+	  terminal up-buffer and its settings.
+
 config SHELL_RTT_RX_POLL_PERIOD
 	int "RX polling period (in milliseconds)"
 	default 10

diff --git a/subsys/shell/backends/shell_rtt.c b/subsys/shell/backends/shell_rtt.c
@@ -9,9 +9,13 @@
 #include <SEGGER_RTT.h>
 #include <zephyr/logging/log.h>
 
-BUILD_ASSERT(!(IS_ENABLED(CONFIG_LOG_BACKEND_RTT) &&
-	       COND_CODE_0(CONFIG_LOG_BACKEND_RTT_BUFFER, (1), (0))),
+#if IS_ENABLED(CONFIG_LOG_BACKEND_RTT)
+BUILD_ASSERT(!(CONFIG_SHELL_BACKEND_RTT_BUFFER == CONFIG_LOG_BACKEND_RTT_BUFFER),
 	     "Conflicting log RTT backend enabled on the same channel");
+#endif
+
+static uint8_t shell_rtt_up_buf[CONFIG_SEGGER_RTT_BUFFER_SIZE_UP];
+static uint8_t shell_rtt_down_buf[CONFIG_SEGGER_RTT_BUFFER_SIZE_DOWN];
 
 SHELL_RTT_DEFINE(shell_transport_rtt);
 SHELL_DEFINE(shell_rtt, CONFIG_SHELL_PROMPT_RTT, &shell_transport_rtt,
@@ -27,7 +31,7 @@ static void timer_handler(struct k_timer *timer)
 {
 	const struct shell_rtt *sh_rtt = k_timer_user_data_get(timer);
 
-	if (SEGGER_RTT_HasData(0)) {
+	if (SEGGER_RTT_HasData(CONFIG_SHELL_BACKEND_RTT_BUFFER)) {
 		sh_rtt->handler(SHELL_TRANSPORT_EVT_RX_RDY, sh_rtt->context);
 	}
 }
@@ -45,7 +49,17 @@ static int init(const struct shell_transport *transport,
 	k_timer_init(&sh_rtt->timer, timer_handler, NULL);
 	k_timer_user_data_set(&sh_rtt->timer, (void *)sh_rtt);
 	k_timer_start(&sh_rtt->timer, K_MSEC(CONFIG_SHELL_RTT_RX_POLL_PERIOD),
-		      K_MSEC(CONFIG_SHELL_RTT_RX_POLL_PERIOD));
+			K_MSEC(CONFIG_SHELL_RTT_RX_POLL_PERIOD));
+
+	if (CONFIG_SHELL_BACKEND_RTT_BUFFER > 0) {
+		SEGGER_RTT_ConfigUpBuffer(CONFIG_SHELL_BACKEND_RTT_BUFFER, "Shell",
+					  shell_rtt_up_buf, sizeof(shell_rtt_up_buf),
+					  SEGGER_RTT_MODE_NO_BLOCK_SKIP);
+
+		SEGGER_RTT_ConfigDownBuffer(CONFIG_SHELL_BACKEND_RTT_BUFFER, "Shell",
+					  shell_rtt_down_buf, sizeof(shell_rtt_down_buf),
+					  SEGGER_RTT_MODE_NO_BLOCK_SKIP);
+	}
 
 	return 0;
 }
@@ -78,12 +92,12 @@ static int write(const struct shell_transport *transport,
 	const uint8_t *data8 = (const uint8_t *)data;
 
 	if (rtt_blocking) {
-		*cnt = SEGGER_RTT_WriteNoLock(0, data8, length);
-		while (SEGGER_RTT_HasDataUp(0)) {
+		*cnt = SEGGER_RTT_WriteNoLock(CONFIG_SHELL_BACKEND_RTT_BUFFER, data8, length);
+		while (SEGGER_RTT_HasDataUp(CONFIG_SHELL_BACKEND_RTT_BUFFER)) {
 			/* empty */
 		}
 	} else {
-		*cnt = SEGGER_RTT_Write(0, data8, length);
+		*cnt = SEGGER_RTT_Write(CONFIG_SHELL_BACKEND_RTT_BUFFER, data8, length);
 	}
 
 	sh_rtt->handler(SHELL_TRANSPORT_EVT_TX_RDY, sh_rtt->context);
@@ -94,7 +108,7 @@ static int write(const struct shell_transport *transport,
 static int read(const struct shell_transport *transport,
 		void *data, size_t length, size_t *cnt)
 {
-	*cnt = SEGGER_RTT_Read(0, data, length);
+	*cnt = SEGGER_RTT_Read(CONFIG_SHELL_BACKEND_RTT_BUFFER, data, length);
 
 	return 0;
 }