feat(ulp-riscv): Added interrupt allocator and de-allocator

This commit adds methods to allocate and de-allocate interrupt handlers
for the ULP RISC-V.

components/ulp/ulp_riscv/ulp_core/include/ulp_riscv_interrupt.h

@@ -0,0 +1,44 @@
+/*
+ * SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+#include <stdint.h>
+#include "esp_err.h"
+#include "riscv/interrupt.h"
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+/* ULP RISC-V Interrupt sources */
+typedef enum {
+    ULP_RISCV_MAX_INTR_SOURCE,              /**< Total number of ULP RISC-V interrupt sources */
+} ulp_riscv_interrupt_source_t;
+
+/**
+ * @brief Allocate interrupt handler for a ULP RISC-V interrupt source
+ *
+ * @param source        ULP RISC-V interrupt source
+ * @param handler       Interrupt handler
+ * @param arg           Interrupt handler argument
+ *
+ * @return esp_err_t    ESP_OK when successful
+ */
+esp_err_t ulp_riscv_intr_alloc(ulp_riscv_interrupt_source_t source, intr_handler_t handler, void *arg);
+
+/**
+ * @brief Free ULP RISC-V interrupt handler
+ *
+ * @param source        ULP RISC-V interrupt source
+ *
+ * @return esp_err_t    ESP_OK when successful
+ */
+esp_err_t ulp_riscv_intr_free(ulp_riscv_interrupt_source_t source);
+
+#ifdef __cplusplus
+}
+#endif

components/ulp/ulp_riscv/ulp_core/ulp_riscv_interrupt.c

@@ -5,6 +5,7 @@
  */
 #include <stdint.h>
 #include "ulp_riscv_register_ops.h"
+#include "ulp_riscv_interrupt.h"
 
 #define ULP_RISCV_TIMER_INT                         (1 << 0U)   /* Internal Timer Interrupt */
 #define ULP_RISCV_EBREAK_ECALL_ILLEGAL_INSN_INT     (1 << 1U)   /* EBREAK, ECALL or Illegal instruction */
@@ -12,6 +13,50 @@
 #define ULP_RISCV_PERIPHERAL_INTERRUPT              (1 << 31U)  /* RTC Peripheral Interrupt */
 #define ULP_RISCV_INTERNAL_INTERRUPT                (ULP_RISCV_TIMER_INT | ULP_RISCV_EBREAK_ECALL_ILLEGAL_INSN_INT | ULP_RISCV_BUS_ERROR_INT)
 
+/* Interrupt handler structure */
+typedef struct {
+    intr_handler_t handler;
+    void *arg;
+} ulp_riscv_intr_handler_t;
+
+/* Statically store all interrupt handlers */
+static ulp_riscv_intr_handler_t s_intr_handlers[ULP_RISCV_MAX_INTR_SOURCE];
+
+esp_err_t ulp_riscv_intr_alloc(ulp_riscv_interrupt_source_t source, intr_handler_t handler, void *arg)
+{
+    /* Check the validity of the interrupt source */
+    if (source < 0 || source >= ULP_RISCV_MAX_INTR_SOURCE || handler == NULL) {
+        return ESP_ERR_INVALID_ARG;
+    }
+
+    /* Register interrupt handler */
+    if (s_intr_handlers[source].handler == NULL) {
+        s_intr_handlers[source].handler = handler;
+        s_intr_handlers[source].arg = arg;
+    } else {
+        /* Error: The interrupt handler for this interrupt source has already been allocated */
+        return ESP_ERR_NOT_FOUND;
+    }
+
+    return ESP_OK;
+}
+
+esp_err_t ulp_riscv_intr_free(ulp_riscv_interrupt_source_t source)
+{
+    /* Check the validity of the interrupt source */
+    if (source < 0 || source >= ULP_RISCV_MAX_INTR_SOURCE) {
+        return ESP_ERR_INVALID_ARG;
+    }
+
+    /* De-register interrupt handler */
+    if (s_intr_handlers[source].handler != NULL) {
+        s_intr_handlers[source].handler = NULL;
+        s_intr_handlers[source].arg = NULL;
+    }
+
+    return ESP_OK;
+}
+
 /* This is the global interrupt handler for ULP RISC-V.
  * It is called from ulp_riscv_vectors.S
  */
@@ -26,12 +71,10 @@ void __attribute__((weak)) _ulp_riscv_interrupt_handler(uint32_t q1)
 
     /* External/Peripheral interrupts */
     if (q1 & ULP_RISCV_PERIPHERAL_INTERRUPT) {
-        // TODO
+        /* TODO: RTC Peripheral interrupts */
 
-        /* Peripheral interrupts */
+        /* TODO: RTC IO interrupts */
 
-        /* RTC I2C interrupt */
+        /* TODO: RTC I2C interrupt */
-
-        /* RTC IO interrupt */
     }
 }