feat: support Wingtech CT2MHS01 hotspot

Add support for the Wingtech CT2MHS01 hotspot, a Qualcomm mdm9650-based
device with a screen available for US$15-35. This device is often used
as a base platform for while labeled versions like the T-Mobile TMOHS1.
AT&T branded versions of the hotspot seem to be the most abundant.

The device has a framebuffer-driven screen at /dev/fb0 that behaves
similarly to the Orbic RC400L, although the userspace program
`displaygui` refreshes the screen significantly more often than on the
Orbic. This causes the green line on the screen to subtly flicker and
only be displayed during some frames. Subsequent work to fully control
the display without removing the OEM interface is desired.

bin/src/display/mod.rs

@@ -15,6 +15,11 @@ mod orbic;
 #[cfg(feature = "orbic")]
 pub use orbic::update_ui;
 
+#[cfg(feature = "wingtech")]
+mod wingtech;
+#[cfg(feature = "wingtech")]
+pub use wingtech::update_ui;
+
 pub enum DisplayState {
     Recording,
     Paused,
@@ -24,5 +29,8 @@ pub enum DisplayState {
 #[cfg(all(feature = "orbic", feature = "tplink"))]
 compile_error!("cannot compile for many devices at once");
 
-#[cfg(not(any(feature = "orbic", feature = "tplink")))]
+#[cfg(all(feature = "orbic", feature = "wingtech"))]
+compile_error!("cannot compile for many devices at once");
+
+#[cfg(not(any(feature = "orbic", feature = "tplink", feature = "wingtech",)))]
 compile_error!("cannot compile for no device at all");

bin/src/display/wingtech.rs

@@ -0,0 +1,54 @@
+/// Display support for the Wingtech CT2MHS01 hotspot.
+///
+/// Tested on (from `/etc/wt_version`):
+///   WT_INNER_VERSION=SW_Q89323AA1_V057_M10_CRICKET_USR_MP
+///   WT_PRODUCTION_VERSION=CT2MHS01_0.04.55
+///   WT_HARDWARE_VERSION=89323_1_20
+use crate::config;
+use crate::display::generic_framebuffer::{self, Dimensions, GenericFramebuffer};
+use crate::display::DisplayState;
+
+use tokio::sync::mpsc::Receiver;
+use tokio::sync::oneshot;
+use tokio_util::task::TaskTracker;
+
+const FB_PATH: &str = "/dev/fb0";
+
+#[derive(Copy, Clone, Default)]
+struct Framebuffer;
+
+impl GenericFramebuffer for Framebuffer {
+    fn dimensions(&self) -> Dimensions {
+        Dimensions {
+            height: 128,
+            width: 160,
+        }
+    }
+
+    fn write_buffer(&mut self, buffer: &[(u8, u8, u8)]) {
+        let mut raw_buffer = Vec::new();
+        for (r, g, b) in buffer {
+            let mut rgb565: u16 = (*r as u16 & 0b11111000) << 8;
+            rgb565 |= (*g as u16 & 0b11111100) << 3;
+            rgb565 |= (*b as u16) >> 3;
+            raw_buffer.extend(rgb565.to_le_bytes());
+        }
+
+        std::fs::write(FB_PATH, &raw_buffer).unwrap();
+    }
+}
+
+pub fn update_ui(
+    task_tracker: &TaskTracker,
+    config: &config::Config,
+    ui_shutdown_rx: oneshot::Receiver<()>,
+    ui_update_rx: Receiver<DisplayState>,
+) {
+    generic_framebuffer::update_ui(
+        task_tracker,
+        config,
+        Framebuffer,
+        ui_shutdown_rx,
+        ui_update_rx,
+    )
+}