dport: Bigfix dport_read code move to IRAM

A new method of workaround an error with DPORT is to ensure that the APB is read and followed by the DPORT register without interruptions and pauses. This fix places this implementation in the IRAM to exclude errors associated with the cache miss.

components/esp32/dport_access.c

@@ -236,3 +236,77 @@ void IRAM_ATTR esp_dport_access_read_buffer(uint32_t *buff_out, uint32_t address
     }
     DPORT_INTERRUPT_RESTORE();
 }
+
+/**
+ * @brief Read value from register, SMP-safe version.
+ *
+ * This method uses the pre-reading of the APB register before reading the register of the DPORT.
+ * This implementation is useful for reading DORT registers for single reading without stall other CPU.
+ * There is disable/enable interrupt.
+ *
+ * @param reg Register address
+ * @return Value
+ */
+uint32_t IRAM_ATTR esp_dport_access_reg_read(uint32_t reg)
+{
+#if defined(BOOTLOADER_BUILD) || defined(CONFIG_FREERTOS_UNICORE) || !defined(ESP_PLATFORM)
+    return _DPORT_REG_READ(reg);
+#else
+    uint32_t apb;
+    unsigned int intLvl;
+    __asm__ __volatile__ (\
+                  "movi %[APB], "XTSTR(0x3ff40078)"\n"\
+                  "rsil %[LVL], "XTSTR(3)"\n"\
+                  "l32i %[APB], %[APB], 0\n"\
+                  "l32i %[REG], %[REG], 0\n"\
+                  "wsr  %[LVL], "XTSTR(PS)"\n"\
+                  "rsync\n"\
+                  : [APB]"=a"(apb), [REG]"+a"(reg), [LVL]"=a"(intLvl)\
+                  : \
+                  : "memory" \
+                  );
+    return reg;
+#endif
+}
+
+/**
+ * @brief Read value from register, NOT SMP-safe version.
+ *
+ * This method uses the pre-reading of the APB register before reading the register of the DPORT.
+ * There is not disable/enable interrupt.
+ * The difference from DPORT_REG_READ() is that the user himself must disable interrupts while DPORT reading.
+ * This implementation is useful for reading DORT registers in loop without stall other CPU. Note the usage example.
+ * The recommended way to read registers sequentially without stall other CPU
+ * is to use the method esp_dport_read_buffer(buff_out, address, num_words). It allows you to read registers in the buffer.
+ *
+ * \code{c}
+ * // This example shows how to use it.
+ * { // Use curly brackets to limit the visibility of variables in macros DPORT_INTERRUPT_DISABLE/RESTORE.
+ *     DPORT_INTERRUPT_DISABLE(); // Disable interrupt only on current CPU.
+ *     for (i = 0; i < max; ++i) {
+ *        array[i] = esp_dport_access_sequence_reg_read(Address + i * 4); // reading DPORT registers
+ *     }
+ *     DPORT_INTERRUPT_RESTORE(); // restore the previous interrupt level
+ * }
+ * \endcode
+ *
+ * @param reg Register address
+ * @return Value
+ */
+uint32_t IRAM_ATTR esp_dport_access_sequence_reg_read(uint32_t reg)
+{
+#if defined(BOOTLOADER_BUILD) || defined(CONFIG_FREERTOS_UNICORE) || !defined(ESP_PLATFORM)
+    return _DPORT_REG_READ(reg);
+#else
+    uint32_t apb;
+    __asm__ __volatile__ (\
+                  "movi %[APB], "XTSTR(0x3ff40078)"\n"\
+                  "l32i %[APB], %[APB], 0\n"\
+                  "l32i %[REG], %[REG], 0\n"\
+                  : [APB]"=a"(apb), [REG]"+a"(reg)\
+                  : \
+                  : "memory" \
+                  );
+    return reg;
+#endif
+}