add width and height support (hack)

1 files changed, 24 insertions, 0 deletions

diff --git a/src/of_node.rs b/src/of_node.rs
new file mode 100644
index 0000000..5dff2a0
--- /dev/null
+++ b/src/of_node.rs
@@ -0,0 +1,24 @@
+// This module is a hack to read additional information in the DT nodes in the
+// kernel to retrieve data that is currently not exposed in the charlcd.c
+// driver.
+
+use std::fs::File;
+use std::io::Result;
+
+use byteorder::{BigEndian, ReadBytesExt};
+
+fn read_u32_node(node_name: &str) -> Result<u32> {
+    let mut f = File::open(format!(
+        "/sys/devices/platform/auxdisplay/of_node/{}",
+        node_name
+    ))?;
+    Ok(f.read_u32::<BigEndian>()?)
+}
+
+pub fn display_height_chars() -> Result<u32> {
+    read_u32_node("display-height-chars")
+}
+
+pub fn display_width_chars() -> Result<u32> {
+    read_u32_node("display-width-chars")
+}