Add set_off_screen ioctl

src/main.rs

@@ -0,0 +1,79 @@
+use clap::Parser;
+use eyre::{Context, ensure, eyre};
+use nix::ioctl_write_ptr;
+use std::{
+    fs::File,
+    io::Read,
+    os::fd::AsRawFd,
+    path::{Path, PathBuf},
+};
+
+#[derive(Parser)]
+struct Opt {
+    /// Path to the image-blob.
+    pub path: PathBuf,
+}
+
+const SCREEN_W: usize = 1404;
+const SCREEN_H: usize = 1872;
+
+const BITS_PER_PIXEL: usize = 4;
+const FILE_SIZE: usize = SCREEN_W * SCREEN_H * BITS_PER_PIXEL / 8;
+
+// const SPI_IOC_MAGIC: u8 = b'k'; // Defined in linux/spi/spidev.h
+// const SPI_IOC_TYPE_MESSAGE: u8 = 0;
+// ioctl_write_buf!(spi_transfer, SPI_IOC_MAGIC, SPI_IOC_TYPE_MESSAGE, spi_ioc_transfer);
+// #define DRM_IOCTL_ROCKCHIP_EBC_OFF_SCREEN	DRM_IOWR(DRM_COMMAND_BASE + 0x01, struct drm_rockchip_ebc_off_screen)
+
+#[repr(C)]
+struct DrmRockchipEbcOffScreen {
+    info1: u64,
+    ptr_screen_content: *const u8,
+}
+
+const DRM_IOCTL_BASE: u8 = b'd';
+const DRM_COMMAND_BASE: u8 = 0x40;
+const ROCKCHIP_EBC_FILE: &str = "/dev/dri/by-path/platform-fdec0000.ebc-card";
+
+ioctl_write_ptr!(
+    set_off_screen,
+    DRM_IOCTL_BASE,
+    DRM_COMMAND_BASE + 1,
+    DrmRockchipEbcOffScreen
+);
+
+fn main() -> eyre::Result<()> {
+    let opt = Opt::parse();
+    color_eyre::install()?;
+
+    let image =
+        read_file(&opt.path).wrap_err_with(|| eyre!("Failed to read file at {:?}", opt.path))?;
+
+    let set_off_screen_data = DrmRockchipEbcOffScreen {
+        info1: 0, // TODO: what is this?
+        ptr_screen_content: image.as_ptr(),
+    };
+
+    let driver_file = File::options()
+        .write(true)
+        .open(ROCKCHIP_EBC_FILE)
+        .wrap_err_with(|| eyre!("Failed to open rockchip ebc file at {ROCKCHIP_EBC_FILE:?}"))?;
+
+    unsafe { set_off_screen(driver_file.as_raw_fd(), &set_off_screen_data) }
+        .wrap_err("ioctl error")?;
+
+    Ok(())
+}
+
+fn read_file(path: &Path) -> eyre::Result<Vec<u8>> {
+    let mut file = File::open(path)?;
+    let mut buf = vec![0u8; FILE_SIZE];
+    file.read_exact(&mut buf[..])
+        .wrap_err_with(|| eyre!("Expected a raw image file, of exactly {FILE_SIZE} bytes"))?;
+
+    // Try to read a single byte. If n != 0, it means the file was larger than FILE_SIZE
+    let n = file.read(&mut [0u8])?;
+    ensure!(n == 0, "File must be exacly {FILE_SIZE} bytes long");
+
+    Ok(buf)
+}