1 files changed, 41 insertions, 0 deletions
diff --git a/sound_card_init/dsm/src/vpd.rs b/sound_card_init/dsm/src/vpd.rs
new file mode 100644
index 00000000..b00864cc
--- /dev/null
+++ b/sound_card_init/dsm/src/vpd.rs
@@ -0,0 +1,41 @@
+// Copyright 2020 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+use std::fs::File;
+use std::io::prelude::*;
+use std::io::BufReader;
+use std::path::PathBuf;
+
+use crate::error::{Error, Result};
+
+const VPD_DIR: &str = "/sys/firmware/vpd/ro/vpdfile";
+
+/// `VPD`, which represents the amplifier factory calibration values.
+#[derive(Default, Debug)]
+pub struct VPD {
+    pub dsm_calib_r0: i32,
+    pub dsm_calib_temp: i32,
+}
+
+impl VPD {
+    /// Creates a `VPD` and initializes its fields from VPD_DIR/dsm_calib_r0_{channel}.
+    /// # Arguments
+    ///
+    /// * `channel` - channel number.
+    pub fn new(channel: usize) -> Result<VPD> {
+        let mut vpd: VPD = Default::default();
+        vpd.dsm_calib_r0 = read_vpd_files(&format!("dsm_calib_r0_{}", channel))?;
+        vpd.dsm_calib_temp = read_vpd_files(&format!("dsm_calib_temp_{}", channel))?;
+        Ok(vpd)
+    }
+}
+
+fn read_vpd_files(file: &str) -> Result<i32> {
+    let path = PathBuf::from(VPD_DIR).with_file_name(file);
+    let io_err = |e| Error::FileIOFailed(path.to_owned(), e);
+    let mut reader = BufReader::new(File::open(&path).map_err(io_err)?);
+    let mut line = String::new();
+    reader.read_line(&mut line).map_err(io_err)?;
+    line.parse::<i32>()
+        .map_err(|e| Error::VPDParseFailed(path.to_string_lossy().to_string(), e))
+}