[nrf noup] logging: Add ratelimited variants

These are helpful for logging in data-path, not to overwhelm the
console but still keep the user informed about the issues.

This is similar to printk_ratelimited in Linux kernel.

Add only basic build tests for now.

Upstream PR #: 93536

[To avoid release notes churn, marking as noup]

Signed-off-by: Chaitanya Tata <[email protected]>

Author: krish2718

doc/services/logging/index.rst

@@ -32,6 +32,7 @@ Summary of the logging features:
 - Support for logging floating point variables and long long arguments.
 - Built-in copying of transient strings used as arguments.
 - Support for multi-domain logging.
+- Rate-limited logging macros to prevent log flooding when messages are generated frequently.
 
 Logging API is highly configurable at compile time as well as at run time. Using
 Kconfig options (see :ref:`logging_kconfig`) logs can be gradually removed from
@@ -59,6 +60,16 @@ The warning level also exposes the following additional macro:
 
 - :c:macro:`LOG_WRN_ONCE` for warnings where only the first occurrence is of interest.
 
+Rate-limited logging macros are also available for all severity levels to prevent log flooding:
+
+- ``LOG_X_RATELIMIT`` for rate-limited standard printf-like messages using default rate, e.g. :c:macro:`LOG_ERR_RATELIMIT`.
+- ``LOG_X_RATELIMIT_RATE`` for rate-limited standard printf-like messages with custom rate, e.g. :c:macro:`LOG_ERR_RATELIMIT_RATE`.
+- ``LOG_HEXDUMP_X_RATELIMIT`` for rate-limited data dumping using default rate, e.g. :c:macro:`LOG_HEXDUMP_WRN_RATELIMIT`.
+- ``LOG_HEXDUMP_X_RATELIMIT_RATE`` for rate-limited data dumping with custom rate, e.g. :c:macro:`LOG_HEXDUMP_WRN_RATELIMIT_RATE`.
+
+The convenience macros use the default rate specified by ``CONFIG_LOG_RATELIMIT_INTERVAL_MS``,
+while the explicit rate macros take a rate parameter (in milliseconds) that specifies the minimum interval between log messages.
+
 There are two configuration categories: configurations per module and global
 configuration. When logging is enabled globally, it works for modules. However,
 modules can disable logging locally. Every module can specify its own logging
@@ -341,6 +352,94 @@ If logs are processed from a thread (user or internal) then it is possible to en
 a feature which will wake up processing thread when certain amount of log messages are
 buffered (see :kconfig:option:`CONFIG_LOG_PROCESS_TRIGGER_THRESHOLD`).
 
+.. _logging_ratelimited:
+
+Rate-limited logging
+********************
+
+Rate-limited logging macros provide a way to prevent log flooding when messages are
+generated frequently. These macros ensure that log messages are not output more
+frequently than a specified interval, similar to Linux's ``printk_ratelimited``
+functionality.
+
+The rate-limited logging system provides two types of macros:
+
+**Convenience macros (using default rate):**
+- :c:macro:`LOG_ERR_RATELIMIT` - Rate-limited error messages
+- :c:macro:`LOG_WRN_RATELIMIT` - Rate-limited warning messages
+- :c:macro:`LOG_INF_RATELIMIT` - Rate-limited info messages
+- :c:macro:`LOG_DBG_RATELIMIT` - Rate-limited debug messages
+- :c:macro:`LOG_HEXDUMP_ERR_RATELIMIT` - Rate-limited error hexdump
+- :c:macro:`LOG_HEXDUMP_WRN_RATELIMIT` - Rate-limited warning hexdump
+- :c:macro:`LOG_HEXDUMP_INF_RATELIMIT` - Rate-limited info hexdump
+- :c:macro:`LOG_HEXDUMP_DBG_RATELIMIT` - Rate-limited debug hexdump
+
+**Explicit rate macros (with custom rate):**
+- :c:macro:`LOG_ERR_RATELIMIT_RATE` - Rate-limited error messages with custom rate
+- :c:macro:`LOG_WRN_RATELIMIT_RATE` - Rate-limited warning messages with custom rate
+- :c:macro:`LOG_INF_RATELIMIT_RATE` - Rate-limited info messages with custom rate
+- :c:macro:`LOG_DBG_RATELIMIT_RATE` - Rate-limited debug messages with custom rate
+- :c:macro:`LOG_HEXDUMP_ERR_RATELIMIT_RATE` - Rate-limited error hexdump with custom rate
+- :c:macro:`LOG_HEXDUMP_WRN_RATELIMIT_RATE` - Rate-limited warning hexdump with custom rate
+- :c:macro:`LOG_HEXDUMP_INF_RATELIMIT_RATE` - Rate-limited info hexdump with custom rate
+- :c:macro:`LOG_HEXDUMP_DBG_RATELIMIT_RATE` - Rate-limited debug hexdump with custom rate
+
+The convenience macros use the default rate specified by :kconfig:option:`CONFIG_LOG_RATELIMIT_INTERVAL_MS`
+(5000ms by default). The explicit rate macros take a rate parameter (in milliseconds) that specifies
+the minimum interval between log messages. The rate limiting is per-macro-call-site, meaning
+that each unique call to a rate-limited macro has its own independent rate limit.
+
+Example usage:
+
+.. code-block:: c
+
+    #include <zephyr/logging/log.h>
+    #include <zephyr/kernel.h>
+
+    LOG_MODULE_REGISTER(my_module, CONFIG_LOG_DEFAULT_LEVEL);
+
+    void process_data(void)
+    {
+        /* Convenience macros using default rate (CONFIG_LOG_RATELIMIT_INTERVAL_MS) */
+        LOG_WRN_RATELIMIT("Data processing warning: %d", error_code);
+        LOG_ERR_RATELIMIT("Critical error occurred: %s", error_msg);
+        LOG_INF_RATELIMIT("Processing status: %d items", item_count);
+        LOG_HEXDUMP_WRN_RATELIMIT(data_buffer, data_len, "Data buffer:");
+
+        /* Explicit rate macros with custom intervals */
+        LOG_WRN_RATELIMIT_RATE(1000, "Fast rate warning: %d", error_code);
+        LOG_ERR_RATELIMIT_RATE(30000, "Slow rate error: %s", error_msg);
+        LOG_INF_RATELIMIT_RATE(2000, "Custom rate status: %d items", item_count);
+        LOG_HEXDUMP_ERR_RATELIMIT_RATE(5000, data_buffer, data_len, "Error data:");
+    }
+
+Rate-limited logging is particularly useful for:
+
+- Error conditions that might occur frequently but don't need to flood the logs
+- Status updates in tight loops or high-frequency callbacks
+- Debug information that could overwhelm the logging system
+- Network or I/O operations that might fail repeatedly
+
+Configuration
+==============
+
+Rate-limited logging can be configured using the following Kconfig options:
+
+- :kconfig:option:`CONFIG_LOG_RATELIMIT` - Master switch to enable/disable rate-limited logging
+- :kconfig:option:`CONFIG_LOG_RATELIMIT_INTERVAL_MS` - Default interval for convenience macros (5000ms)
+
+When :kconfig:option:`CONFIG_LOG_RATELIMIT` is disabled, the behavior of rate-limited macros is controlled
+by the :kconfig:option:`CONFIG_LOG_RATELIMIT_FALLBACK` choice:
+
+- :kconfig:option:`CONFIG_LOG_RATELIMIT_FALLBACK_LOG` - All rate-limited macros behave as regular logging macros
+- :kconfig:option:`CONFIG_LOG_RATELIMIT_FALLBACK_DROP` - All rate-limited macros expand to no-ops (default)
+
+This allows you to control whether rate-limited log macros should always print or be completely
+suppressed when rate limiting is not available.
+
+The rate limiting is implemented using static variables and :c:func:`k_uptime_get_32`
+to track the last log time for each call site.
+
 .. _logging_panic:
 
 Logging panic