feat(ulp-riscv): Added utility functions for atomicity

This commit adds utility functions to enter and exit critical sections
in the code flow by disabling and enabling interrupts.

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

@@ -132,6 +132,32 @@ void ulp_riscv_disable_sw_intr(void);
  */
 void ulp_riscv_trigger_sw_intr(void);
 
+/**
+ * @brief Enter a critical section by disabling all interrupts
+ *        This inline assembly construct uses the t0 register and is equivalent to:
+ *
+ *        li t0, 0x80000007
+ *        maskirq_insn(zero, t0)    // Mask all interrupt bits
+ */
+#define ULP_RISCV_ENTER_CRITICAL()  \
+    asm volatile (                  \
+        "li t0, 0x80000007\n"       \
+        ".word 0x0602e00b"          \
+    );                              \
+
+/**
+ * @brief Exit a critical section by enabling all interrupts
+ *        This inline assembly construct is equivalent to:
+ *
+ *        maskirq_insn(zero, zero)  // Unmask all interrupt bits
+ */
+#define ULP_RISCV_EXIT_CRITICAL()   asm volatile (".word 0x0600600b");
+
+#else /* CONFIG_ULP_RISCV_INTERRUPT_ENABLE */
+
+#define ULP_RISCV_ENTER_CRITICAL()
+#define ULP_RISCV_EXIT_CRITICAL()
+
 #endif /* CONFIG_ULP_RISCV_INTERRUPT_ENABLE */
 
 #ifdef __cplusplus