feat(vbat): Add support to use vbat as rtc battery

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

@@ -219,6 +219,10 @@ config SOC_BOD_SUPPORTED
     bool
     default y
 
+config SOC_VBAT_SUPPORTED
+    bool
+    default y
+
 config SOC_APM_SUPPORTED
     bool
     default y

components/soc/esp32p4/include/soc/regi2c_brownout.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022-2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -23,3 +23,26 @@
 #define I2C_BOD_THRESHOLD_H           0x9
 #define I2C_BOD_THRESHOLD_H_MSB       7
 #define I2C_BOD_THRESHOLD_H_LSB       5
+
+#define I2C_BIAS_OR_DREF_VBAT_L       8
+#define I2C_BIAS_OR_DREF_VBAT_L_MSB   4
+#define I2C_BIAS_OR_DREF_VBAT_L_LSB   2
+#define I2C_BIAS_OR_DREF_VBAT_H       8
+#define I2C_BIAS_OR_DREF_VBAT_H_MSB   7
+#define I2C_BIAS_OR_DREF_VBAT_H_LSB   5
+
+#define I2C_BIAS_OR_DREF_VBAT_CHARGER_L       10
+#define I2C_BIAS_OR_DREF_VBAT_CHARGER_L_MSB   4
+#define I2C_BIAS_OR_DREF_VBAT_CHARGER_L_LSB   2
+#define I2C_BIAS_OR_DREF_VBAT_CHARGER_H       10
+#define I2C_BIAS_OR_DREF_VBAT_CHARGER_H_MSB   7
+#define I2C_BIAS_OR_DREF_VBAT_CHARGER_H_LSB   5
+
+#define I2C_BIAS_OR_FORCE_PU_VBAT_CHARGER 10
+#define I2C_BIAS_OR_FORCE_PU_VBAT_CHARGER_MSB 0
+#define I2C_BIAS_OR_FORCE_PU_VBAT_CHARGER_LSB 0
+
+/** Change the charging current by adjusting the value of the series resistor. 1kΩ + N * 0.5kΩ */
+#define I2C_BIAS_OR_DRES_CHARGER     3
+#define I2C_BIAS_OR_DRES_CHARGER_MSB 7
+#define I2C_BIAS_OR_DRES_CHARGER_LSB 4

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

@@ -71,6 +71,7 @@
 #define SOC_FLASH_ENC_SUPPORTED         1
 #define SOC_SECURE_BOOT_SUPPORTED       1
 #define SOC_BOD_SUPPORTED               1
+#define SOC_VBAT_SUPPORTED              1
 #define SOC_APM_SUPPORTED               1
 #define SOC_PMU_SUPPORTED               1
 #define SOC_DCDC_SUPPORTED              1