fix(ulp): fix lp uart keep wakeup triggered

components/soc/esp32c5/include/soc/Kconfig.soc_caps.in

@@ -1682,3 +1682,7 @@ config SOC_LP_CORE_SUPPORT_ETM
 config SOC_LP_CORE_SUPPORT_STORE_LOAD_EXCEPTIONS
     bool
     default y
+
+config SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED
+    bool
+    default y

components/soc/esp32c5/include/soc/soc_caps.h

@@ -673,3 +673,4 @@
 #define SOC_LP_CORE_SINGLE_INTERRUPT_VECTOR         (1) /*!< LP Core interrupts all map to a single entry in vector table */
 #define SOC_LP_CORE_SUPPORT_ETM                     (1) /*!< LP Core supports ETM */
 #define SOC_LP_CORE_SUPPORT_STORE_LOAD_EXCEPTIONS   (1) /*!< LP Core will raise exceptions if accessing invalid addresses */
+#define SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED   (1) /*!< LP UART wakeup source is kept triggered */

components/soc/esp32c6/include/soc/Kconfig.soc_caps.in

@@ -1431,6 +1431,10 @@ config SOC_LP_CORE_SUPPORT_ETM
     bool
     default y
 
+config SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED
+    bool
+    default y
+
 config SOC_DEBUG_HAVE_OCD_STUB_BINS
     bool
     default y

components/soc/esp32c6/include/soc/soc_caps.h

@@ -588,6 +588,7 @@
 /*------------------------------------- ULP CAPS -------------------------------------*/
 #define SOC_LP_CORE_SINGLE_INTERRUPT_VECTOR   (1) /*!< LP Core interrupts all map to a single entry in vector table */
 #define SOC_LP_CORE_SUPPORT_ETM               (1) /*!< LP Core supports ETM */
+#define SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED   (1) /*!< LP UART wakeup source is kept triggered */
 
 /*------------------------------------- DEBUG CAPS -------------------------------------*/
 #define SOC_DEBUG_HAVE_OCD_STUB_BINS    (1)

components/soc/esp32p4/include/soc/Kconfig.soc_caps.in

@@ -1986,3 +1986,7 @@ config SOC_LP_CORE_SUPPORT_LP_ADC
 config SOC_LP_CORE_SUPPORT_STORE_LOAD_EXCEPTIONS
     bool
     default y
+
+config SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED
+    bool
+    default y

components/soc/esp32p4/include/soc/soc_caps.h

@@ -769,3 +769,4 @@
 #define SOC_LP_CORE_SUPPORT_ETM                     (1) /*!< LP Core supports ETM */
 #define SOC_LP_CORE_SUPPORT_LP_ADC                  (1) /*!< LP ADC can be accessed from the LP-Core */
 #define SOC_LP_CORE_SUPPORT_STORE_LOAD_EXCEPTIONS   (1) /*!< LP Core will raise exceptions if accessing invalid addresses */
+#define SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED   (1) /*!< LP UART wakeup source is kept triggered */

components/ulp/lp_core/lp_core/lp_core_utils.c

@@ -25,9 +25,19 @@
 
 #include "esp_cpu.h"
 #include "ulp_lp_core_cpu_freq_shared.h"
+#include "ulp_lp_core_lp_uart_shared.h"
+#include "ulp_lp_core_uart.h"
 
 static uint32_t lp_wakeup_cause = 0;
 
+#if SOC_ULP_LP_UART_SUPPORTED
+void ulp_lp_core_lp_uart_reset_wakeup_en(void)
+{
+    lp_core_ll_enable_lp_uart_wakeup(false);
+    lp_core_ll_enable_lp_uart_wakeup(true);
+}
+#endif
+
 void ulp_lp_core_update_wakeup_cause(void)
 {
     lp_wakeup_cause = 0;
@@ -42,6 +52,13 @@ void ulp_lp_core_update_wakeup_cause(void)
             && (uart_ll_get_intraw_mask(&LP_UART) & LP_UART_WAKEUP_INT_RAW)) {
         lp_wakeup_cause |= LP_CORE_LL_WAKEUP_SOURCE_LP_UART;
         uart_ll_clr_intsts_mask(&LP_UART, LP_UART_WAKEUP_INT_CLR);
+#if SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED
+        // In these chips, the LP UART wakeup source is kept triggered, so we need to
+        // reset the wakeup register and flush the UART buffer manually after waking up.
+        lp_core_uart_tx_flush(LP_UART_NUM_0);
+        lp_core_uart_clear_buf();
+        ulp_lp_core_lp_uart_reset_wakeup_en();
+#endif
     }
 #endif
 
@@ -133,15 +150,6 @@ void ulp_lp_core_delay_cycles(uint32_t cycles)
     }
 }
 
-#if SOC_ULP_LP_UART_SUPPORTED
-
-void ulp_lp_core_lp_uart_reset_wakeup_en(void)
-{
-    lp_core_ll_enable_lp_uart_wakeup(false);
-    lp_core_ll_enable_lp_uart_wakeup(true);
-}
-#endif
-
 void ulp_lp_core_halt(void)
 {
     lp_core_ll_request_sleep();

components/ulp/lp_core/shared/include/ulp_lp_core_lp_uart_shared.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2024-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -18,9 +18,10 @@ extern "C" {
  *
  * @note This function configures the LP UART wakeup mode. Ensure that the UART has already been initialized
  *       with the lp_core_uart_init() call.
- *       Once the LP Core wakes up due to the LP UART, the wakeup feature is disabled.
- *       To re-enable the wakeup from the LP UART, you must call
- *       ulp_lp_core_lp_uart_reset_wakeup_en() again before the LP core goes to sleep.
+ *       Once the LP Core wakes up due to the LP UART, the wakeup will be kept triggered in the chips with
+ *       SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED. You need to call ulp_lp_core_lp_uart_reset_wakeup_en()
+ *       to reset the wakeup signal and the UART buffer manually after waking up, which is done in ulp
+ *       startup phase.
  *       Also be aware of limitations in different modes mentioned in the uart_wakeup_cfg_t struct.
  *
  *

components/ulp/test_apps/lp_core/lp_core_basic_tests/main/lp_core/test_main_uart_wakeup.c

@@ -1,19 +1,17 @@
 /*
- * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2024-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
 
 #include "ulp_lp_core_utils.h"
 #include "ulp_lp_core_print.h"
-#include "ulp_lp_core_lp_uart_shared.h"
-#include "lp_core_uart.h"
 #include "ulp_lp_core_uart.h"
 
 int main(void)
 {
     lp_core_printf("Hello world\r\n");
-    ulp_lp_core_delay_us(5000);
-    lp_core_uart_clear_buf();
-    ulp_lp_core_lp_uart_reset_wakeup_en();
+    lp_core_uart_tx_flush(LP_UART_NUM_0);
+
+    return 0;
 }

docs/en/api-reference/system/sleep_modes.rst

@@ -365,6 +365,24 @@ After waking-up from UART, you should send some extra data through the UART port
 
            In Light-sleep mode, setting Kconfig option :ref:`CONFIG_PM_POWER_DOWN_PERIPHERAL_IN_LIGHT_SLEEP` will invalidate UART wakeup.
 
+.. only:: SOC_ULP_LP_UART_SUPPORTED
+
+    LP_UART can wake up the ULP LP core coprocessor. LP_UART supports the same wakeup modes as the HP UART described above, including active edge threshold wakeup, RX FIFO threshold wakeup, start bit detection wakeup, and character sequence detection wakeup.
+
+    To use LP_UART to wake up the ULP LP core, follow these steps:
+
+    #. Set the :c:macro:`ULP_LP_CORE_WAKEUP_SOURCE_LP_UART` flag in the ``wakeup_source`` field of the :cpp:type:`ulp_lp_core_cfg_t` structure.
+    #. Initialize the LP UART (call :cpp:func:`lp_core_uart_init`).
+    #. Configure the LP_UART wakeup mode using the :cpp:func:`lp_core_uart_wakeup_setup` function with a :cpp:type:`uart_wakeup_cfg_t` structure, using the same configuration method as HP UART.
+
+    .. only:: SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED
+
+       .. note::
+
+           On chips with ``SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED``, the LP UART wakeup signal remains triggered after a wakeup event. The LP core startup flow (:cpp:func:`ulp_lp_core_update_wakeup_cause`) automatically calls :cpp:func:`ulp_lp_core_lp_uart_reset_wakeup_en` and :cpp:func:`lp_core_uart_clear_buf` to clear this state. If the standard startup flow is not used, you must handle this manually; otherwise, repeated wakeups will occur.
+
+    For example code on LP_UART wakeup, refer to :example:`system/ulp/lp_core/lp_uart/lp_uart_char_seq_wakeup`.
+
 .. _disable_sleep_wakeup_source:
 
 Disable Sleep Wakeup Source

docs/zh_CN/api-reference/system/sleep_modes.rst

@@ -365,6 +365,24 @@ UART 唤醒（仅适用于 Light-sleep 模式）
 
            在 Light-sleep 模式下，设置 Kconfig 选项 :ref:`CONFIG_PM_POWER_DOWN_PERIPHERAL_IN_LIGHT_SLEEP` 将使 UART 唤醒失效。
 
+.. only:: SOC_ULP_LP_UART_SUPPORTED
+
+    LP_UART 可以将 ULP LP 内核协处理器唤醒。LP_UART 支持的唤醒模式与上述 HP UART 唤醒模式相同，包括边沿阈值唤醒、RX FIFO 阈值唤醒、起始位检测唤醒和字符序列检测唤醒。
+
+    要使用 LP_UART 唤醒 ULP LP 内核，需要执行以下步骤：
+
+    #. 在 :cpp:type:`ulp_lp_core_cfg_t` 结构体的 ``wakeup_source`` 字段中设置 :c:macro:`ULP_LP_CORE_WAKEUP_SOURCE_LP_UART` 标志位。
+    #. 初始化 LP UART（调用 :cpp:func:`lp_core_uart_init`）。
+    #. 使用 :cpp:func:`lp_core_uart_wakeup_setup` 函数配置 LP_UART 的唤醒模式，参数使用 :cpp:type:`uart_wakeup_cfg_t` 结构体，配置方式与 HP UART 相同。
+
+    .. only:: SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED
+
+       .. note::
+
+           在支持 ``SOC_LP_CORE_LP_UART_WAKEUP_KEEP_TRIGGERED`` 的芯片上，LP UART 唤醒后唤醒信号会保持触发状态。LP 核启动流程（:cpp:func:`ulp_lp_core_update_wakeup_cause`）会自动调用 :cpp:func:`ulp_lp_core_lp_uart_reset_wakeup_en` 和 :cpp:func:`lp_core_uart_clear_buf` 清除该状态。若未走标准启动流程，则需手动处理，否则会被重复唤醒。
+
+    有关 LP_UART 唤醒的示例代码，请参考 :example:`system/ulp/lp_core/lp_uart/lp_uart_char_seq_wakeup`。
+
 .. _disable_sleep_wakeup_source:
 
 禁用睡眠模式唤醒源

examples/system/ulp/lp_core/lp_uart/lp_uart_char_seq_wakeup/main/lp_core/main.c

@@ -1,20 +1,17 @@
 /*
- * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2024-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
 
 #include "ulp_lp_core_utils.h"
 #include "ulp_lp_core_print.h"
-#include "ulp_lp_core_lp_uart_shared.h"
+#include "ulp_lp_core_uart.h"
 
 int main (void)
 {
     lp_core_printf("Hello world\r\n");
+    lp_core_uart_tx_flush(LP_UART_NUM_0);
 
-    // If you want to make it possible to wake up from UART after sleep,
-    // you have to reset the wakeup register and the UART buffer manually.
-    // ulp_lp_core_lp_uart_reset_wakeup_en();
-    // lp_core_uart_clear_buf();
     return 0;
 }