system: determine the LXA TAC hardware generation from devicetree

Signed-off-by: Leonard Göhrs <[email protected]>

Author: hnez

openapi.yaml

@@ -347,6 +347,21 @@ paths:
               schema:
                 type: string
 
+  /v1/tac/info/hardware_generation:
+    get:
+      summary: Get the LXA TAC hardware generation
+      tags: [System]
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                type: string
+                enum:
+                  - Gen1
+                  - Gen2
+                  - Gen3
+
   /v1/tac/setup_mode:
     get:
       summary: Check if the TAC has completed the set up or is still in setup mode

src/main.rs

@@ -50,7 +50,7 @@ use iobus::IoBus;
 use led::Led;
 use regulators::Regulators;
 use setup_mode::SetupMode;
-use system::System;
+use system::{HardwareGeneration, System};
 use temperatures::Temperatures;
 use ui::{message, setup_display, ScreenShooter, Ui, UiResources};
 use usb_hub::UsbHub;
@@ -68,6 +68,10 @@ async fn init(screenshooter: ScreenShooter) -> Result<(Ui, WatchedTasksBuilder)>
     // The topics are also used to pass around data inside the tacd.
     let mut bb = BrokerBuilder::new();
 
+    // We need to know which generation of LXA TAC we are running on at various
+    // places in the init process.
+    let hardware_generation = HardwareGeneration::get()?;
+
     // Expose hardware on the TAC via the broker framework.
     let backlight = Backlight::new(&mut bb, &mut wtb)?;
     let led = Led::new(&mut bb, &mut wtb)?;
@@ -110,7 +114,7 @@ async fn init(screenshooter: ScreenShooter) -> Result<(Ui, WatchedTasksBuilder)>
 
     // Expose information about the system provided by the kernel via the
     // broker framework.
-    let system = System::new(&mut bb);
+    let system = System::new(&mut bb, hardware_generation);
 
     // Make sure the ADC and power switching threads of the tacd are not
     // stalled for too long by providing watchdog events to systemd

src/system.rs

@@ -15,6 +15,7 @@
 // with this program; if not, write to the Free Software Foundation, Inc.,
 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+use anyhow::{bail, Result};
 use async_std::sync::Arc;
 use nix::sys::utsname::uname;
 use serde::{Deserialize, Serialize};
@@ -24,6 +25,10 @@ use crate::broker::{BrokerBuilder, Topic};
 #[cfg(feature = "demo_mode")]
 mod read_dt_props {
     const DEMO_DATA_STR: &[(&str, &str)] = &[
+        (
+            "compatible",
+            "lxa,stm32mp153c-tac-gen3\0oct,stm32mp15xx-osd32\0st,stm32mp153",
+        ),
         ("chosen/barebox-version", "barebox-2022.11.0-20221121-1"),
         (
             "chosen/baseboard-factory-data/pcba-hardware-release",
@@ -141,23 +146,53 @@ impl Barebox {
     }
 }
 
+#[derive(Clone, Copy, Serialize, Deserialize)]
+pub enum HardwareGeneration {
+    Gen1,
+    Gen2,
+    Gen3,
+}
+
+impl HardwareGeneration {
+    pub fn get() -> Result<Self> {
+        let compatible = read_dt_property("compatible");
+
+        // The compatible property consists of strings separated by NUL bytes.
+        // We are interested in the first of these strings.
+        let device = compatible.split('\0').next().unwrap_or("<empty>");
+
+        match device {
+            "lxa,stm32mp157c-tac-gen1" => Ok(Self::Gen1),
+            "lxa,stm32mp157c-tac-gen2" => Ok(Self::Gen2),
+            "lxa,stm32mp153c-tac-gen3" => Ok(Self::Gen3),
+            gen => bail!("Running on unknown LXA TAC hardware generation \"{gen}\""),
+        }
+    }
+}
+
 pub struct System {
     #[allow(dead_code)]
     pub uname: Arc<Topic<Arc<Uname>>>,
     #[allow(dead_code)]
     pub barebox: Arc<Topic<Arc<Barebox>>>,
     #[allow(dead_code)]
     pub tacd_version: Arc<Topic<String>>,
+    #[allow(dead_code)]
+    pub hardware_generation: Arc<Topic<HardwareGeneration>>,
 }
 
 impl System {
-    pub fn new(bb: &mut BrokerBuilder) -> Self {
+    pub fn new(bb: &mut BrokerBuilder, hardware_generation: HardwareGeneration) -> Self {
         let version = env!("VERSION_STRING").to_string();
 
         Self {
             uname: bb.topic_ro("/v1/tac/info/uname", Some(Arc::new(Uname::get()))),
             barebox: bb.topic_ro("/v1/tac/info/bootloader", Some(Arc::new(Barebox::get()))),
             tacd_version: bb.topic_ro("/v1/tac/info/tacd/version", Some(version)),
+            hardware_generation: bb.topic_ro(
+                "/v1/tac/info/hardware_generation",
+                Some(hardware_generation),
+            ),
         }
     }
 }