zephyr/console: Add console buffer logging backendstabilize-15120.B-main

Add a zephyr logging backend for the console buffer. This allows the AP
to access the logs sent to the zephyr logging subsystem.

This backend will not run in LOG_MODE_MINIMAL, so it may not be usable
for some EC OS projects.

BUG=b:243709788
BRANCH=None
TEST='ectool console' on Skyrim in immediate and deferred logging mode.

Signed-off-by: Rob Barnes <robbarnes@google.com>
Change-Id: I24d9ffeb5c90c99982c70ac2bcbdc0f814b45b01
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3853303
Reviewed-by: Keith Short <keithshort@chromium.org>
Reviewed-by: Jeremy Bettis <jbettis@chromium.org>

3 files changed, 80 insertions, 0 deletions

diff --git a/zephyr/Kconfig.console b/zephyr/Kconfig.console
index 75a4ca7879..74de199067 100644
--- a/zephyr/Kconfig.console
+++ b/zephyr/Kconfig.console
@@ -66,3 +66,25 @@ menuconfig PLATFORM_EC_CONSOLE_DEBUG
 	  Write all zephyr_print() messages to printk() also. Not recommended
 	  outside of tests.
 
+
+config PLATFORM_EC_LOG_BACKEND_CONSOLE_BUFFER
+	bool "Logging backend for the console buffer"
+	depends on PLATFORM_EC_HOSTCMD_CONSOLE
+	select LOG_OUTPUT
+	help
+	  Enable the logging backend for the console buffer.
+
+	  This will copy messages sent to the zephyr logging subsystem
+	  to the EC console buffer. This allows the AP to access the
+	  log messages with the console host command.
+
+config PLATFORM_EC_LOG_BACKEND_CONSOLE_BUFFER_TMP_BUF_SIZE
+	int "Size of temporary buffer used by console buffer logging backend"
+	default 128 if LOG_MODE_DEFERRED
+	default 1
+	depends on PLATFORM_EC_LOG_BACKEND_CONSOLE_BUFFER
+	help
+	  The size of the temporary buffer used by the console buffer backend.
+	  The logging subsystem will buffer up to this many bytes before calling
+	  the backend in deferred logging mode. Ideally this will be large
+	  enough to fit an entire log line.
diff --git a/zephyr/shim/src/CMakeLists.txt b/zephyr/shim/src/CMakeLists.txt
index 636f8ba5c9..97968e8a52 100644
--- a/zephyr/shim/src/CMakeLists.txt
+++ b/zephyr/shim/src/CMakeLists.txt
@@ -43,6 +43,8 @@ if (NOT DEFINED CONFIG_PLATFORM_EC_KEYBOARD_DISCRETE)
                                                             keyboard_raw.c)
 endif()
 zephyr_library_sources_ifdef(CONFIG_PLATFORM_EC_KEYBOARD    keyscan.c)
+zephyr_library_sources_ifdef(CONFIG_PLATFORM_EC_LOG_BACKEND_CONSOLE_BUFFER
+                             log_backend_console_buffer.c)
 zephyr_library_sources_ifdef(CONFIG_PLATFORM_EC_MKBP_EVENT  mkbp_event.c)
 zephyr_library_sources_ifdef(CONFIG_PLATFORM_EC_MOTIONSENSE
                                                             motionsense_sensors.c)
diff --git a/zephyr/shim/src/log_backend_console_buffer.c b/zephyr/shim/src/log_backend_console_buffer.c
new file mode 100644
index 0000000000..cafb690b87
--- /dev/null
+++ b/zephyr/shim/src/log_backend_console_buffer.c
@@ -0,0 +1,56 @@
+/* Copyright 2022 The ChromiumOS Authors.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <zephyr/logging/log_backend.h>
+#include <zephyr/logging/log_output.h>
+#include <zephyr/logging/log_backend_std.h>
+
+#include "console.h"
+
+static uint8_t
+	char_out_buf[CONFIG_PLATFORM_EC_LOG_BACKEND_CONSOLE_BUFFER_TMP_BUF_SIZE];
+
+static int char_out(uint8_t *data, size_t length, void *ctx)
+{
+	/*
+	 * console_buf_notify_chars uses a mutex, which may not be
+	 * locked in ISRs.
+	 */
+	if (k_is_in_isr())
+		return 0;
+	return console_buf_notify_chars(data, length);
+}
+LOG_OUTPUT_DEFINE(log_output_console_buffer, char_out, char_out_buf,
+		  sizeof(char_out_buf));
+
+static void process(const struct log_backend *const backend,
+		    union log_msg_generic *msg)
+{
+	uint32_t flags = log_backend_std_get_flags();
+	log_format_func_t log_output_func =
+		log_format_func_t_get(LOG_OUTPUT_TEXT);
+	log_output_func(&log_output_console_buffer, &msg->log, flags);
+}
+
+static void panic(struct log_backend const *const backend)
+{
+	log_backend_std_panic(&log_output_console_buffer);
+}
+
+static void dropped(const struct log_backend *const backend, uint32_t cnt)
+{
+	log_backend_std_dropped(&log_output_console_buffer, cnt);
+}
+
+const struct log_backend_api log_backend_console_buffer_api = {
+	.process = process,
+	.panic = panic,
+	.dropped = IS_ENABLED(CONFIG_LOG_MODE_DEFERRED) ? dropped : NULL,
+	/* TODO(b/244170593): Support switching output formats */
+	.format_set = NULL,
+};
+
+LOG_BACKEND_DEFINE(log_backend_console_buffer, log_backend_console_buffer_api,
+		   true);