adc_cal: c2: Add efuse functions for reading calibration

esp-hal-common/src/soc/esp32c2/efuse.rs

@@ -1,7 +1,7 @@
 //! Reading of eFuses
 
-use crate::peripherals::EFUSE;
 pub use crate::soc::efuse_field::*;
+use crate::{adc::Attenuation, peripherals::EFUSE};
 
 pub struct Efuse;
 
@@ -36,6 +36,102 @@ impl Efuse {
     pub fn get_rwdt_multiplier() -> u8 {
         Self::read_field_le::<u8>(WDT_DELAY_SEL)
     }
+
+    /// Get efuse block version
+    ///
+    /// see https://github.com/espressif/esp-idf/blob/dc016f5987/components/hal/efuse_hal.c#L27-L30
+    pub fn get_block_version() -> (u8, u8) {
+        // see https://github.com/espressif/esp-idf/blob/dc016f5987/components/hal/esp32c2/include/hal/efuse_ll.h#L65-L73
+        // https://github.com/espressif/esp-idf/blob/903af13e8/components/efuse/esp32c2/esp_efuse_table.csv#L90-L91
+        (
+            Self::read_field_le::<u8>(BLK_VERSION_MAJOR),
+            Self::read_field_le::<u8>(BLK_VERSION_MINOR),
+        )
+    }
+
+    /// Get version of RTC calibration block
+    ///
+    /// see https://github.com/espressif/esp-idf/blob/903af13e8/components/efuse/esp32c2/esp_efuse_rtc_calib.c#L14
+    pub fn get_rtc_calib_version() -> u8 {
+        let (major, _minor) = Self::get_block_version();
+        if major == 0 {
+            1
+        } else {
+            0
+        }
+    }
+
+    /// Get ADC initial code for specified attenuation from efuse
+    ///
+    /// see https://github.com/espressif/esp-idf/blob/903af13e8/components/efuse/esp32c2/esp_efuse_rtc_calib.c#L27
+    pub fn get_rtc_calib_init_code(_unit: u8, atten: Attenuation) -> Option<u16> {
+        let version = Self::get_rtc_calib_version();
+
+        if version != 1 {
+            return None;
+        }
+
+        // see https://github.com/espressif/esp-idf/blob/903af13e8/components/efuse/esp32c2/esp_efuse_table.csv#L94
+        let diff_code0: u16 = Self::read_field_le(ADC1_INIT_CODE_ATTEN0);
+        let code0 = if diff_code0 & (1 << 7) != 0 {
+            2160 - (diff_code0 & 0x7f)
+        } else {
+            2160 + diff_code0
+        };
+
+        if matches!(atten, Attenuation::Attenuation0dB) {
+            return Some(code0);
+        }
+
+        // see https://github.com/espressif/esp-idf/blob/903af13e8/components/efuse/esp32c2/esp_efuse_table.csv#L95
+        let diff_code11: u16 = Self::read_field_le(ADC1_INIT_CODE_ATTEN3);
+        let code11 = code0 + diff_code11;
+
+        Some(code11)
+    }
+
+    /// Get ADC reference point voltage for specified attenuation in millivolts
+    ///
+    /// see https://github.com/espressif/esp-idf/blob/903af13e8/components/efuse/esp32c2/esp_efuse_rtc_calib.c#L65
+    pub fn get_rtc_calib_cal_mv(_unit: u8, atten: Attenuation) -> u16 {
+        match atten {
+            Attenuation::Attenuation0dB => 400,
+            Attenuation::Attenuation11dB => 1370,
+        }
+    }
+
+    /// Get ADC reference point digital code for specified attenuation
+    ///
+    /// see https://github.com/espressif/esp-idf/blob/903af13e8/components/efuse/esp32c2/esp_efuse_rtc_calib.c#L65
+    pub fn get_rtc_calib_cal_code(_unit: u8, atten: Attenuation) -> Option<u16> {
+        let version = Self::get_rtc_calib_version();
+
+        if version != 1 {
+            return None;
+        }
+
+        // see https://github.com/espressif/esp-idf/blob/903af13e8/components/efuse/esp32c2/esp_efuse_table.csv#L96
+        let diff_code0: u16 = Self::read_field_le(ADC1_CAL_VOL_ATTEN0);
+        let code0 = if diff_code0 & (1 << 7) != 0 {
+            1540 - (diff_code0 & 0x7f)
+        } else {
+            1540 + diff_code0
+        };
+
+        if matches!(atten, Attenuation::Attenuation0dB) {
+            return Some(code0);
+        }
+
+        // see https://github.com/espressif/esp-idf/blob/903af13e8/components/efuse/esp32c2/esp_efuse_table.csv#L97
+        let diff_code11: u16 = Self::read_field_le(ADC1_CAL_VOL_ATTEN3);
+        let code11 = if diff_code0 & (1 << 5) != 0 {
+            code0 - (diff_code11 & 0x1f)
+        } else {
+            code0 + diff_code11
+        } - 123;
+
+        Some(code11)
+    }
 }
 
 #[derive(Copy, Clone)]