stm32xx-sys: configure EXTI IRQs in app.toml

This commit adds build-time code generation for the EXTI IRQ dispatch
table. Now, an app.toml can define a section like this:

```toml
[config.sys.gpio-irq.button]
port = "C"
pin = 13
owner = { name = "mytask", notification = "button" }
```

To assign PC13's EXTI IRQ to the `button` notification for task
`mytask`. The dispatch table is now generated by `build/stm32xx-sys` and
will include the EXTI interrupt configurations in the config.

app/demo-stm32h7-nucleo/app-h753.toml

@@ -25,11 +25,22 @@ request_reset = ["hiffy"]
 
 [tasks.sys]
 name = "drv-stm32xx-sys"
-features = ["h753"]
+features = ["h753", "exti"]
 priority = 1
-uses = ["rcc", "gpios", "system_flash"]
+max-sizes = {flash = 4096, ram = 2048}
+uses = ["rcc", "gpios", "system_flash", "syscfg", "exti"]
 start = true
 task-slots = ["jefe"]
+notifications = ["exti-wildcard-irq"]
+
+[tasks.sys.interrupts]
+"exti.exti0" = "exti-wildcard-irq"
+"exti.exti1" = "exti-wildcard-irq"
+"exti.exti2" = "exti-wildcard-irq"
+"exti.exti3" = "exti-wildcard-irq"
+"exti.exti4" = "exti-wildcard-irq"
+"exti.exti9_5" = "exti-wildcard-irq"
+"exti.exti15_10" = "exti-wildcard-irq"
 
 [tasks.i2c_driver]
 name = "drv-stm32xx-i2c-server"
@@ -145,6 +156,7 @@ max-sizes = {flash = 32768, ram = 32768 }
 stacksize = 2048
 start = true
 task-slots = ["sys", "i2c_driver", "hf", "hash_driver"]
+notifications = ["button"]
 
 [tasks.hf]
 name = "drv-gimlet-hf-server"
@@ -259,3 +271,8 @@ owner = {name = "udprpc", notification = "socket"}
 port = 998
 tx = { packets = 3, bytes = 1024 }
 rx = { packets = 3, bytes = 1024 }
+
+[config.sys.gpio-irqs.button]
+port = "C"
+pin = 13
+owner = {name = "hiffy", notification = "button"}

build/stm32xx-sys/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "build-stm32xx-sys"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+anyhow = { workspace = true }
+cfg-if = { workspace = true }
+convert_case = { workspace = true }
+proc-macro2 = { workspace = true }
+quote = { workspace = true }
+serde = { workspace = true }
+syn = { workspace = true }
+
+build-util = { path = "../util" }

build/stm32xx-sys/src/lib.rs

@@ -0,0 +1,148 @@
+use quote::{quote, TokenStreamExt};
+use serde::Deserialize;
+use std::collections::BTreeMap;
+
+/// This represents our _subset_ of global config and _must not_ be marked with
+/// `deny_unknown_fields`!
+#[derive(Deserialize)]
+#[serde(rename_all = "kebab-case")]
+struct GlobalConfig {
+    sys: SysConfig,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "kebab-case", deny_unknown_fields)]
+pub struct SysConfig {
+    /// EXTI interrupts
+    gpio_irqs: BTreeMap<String, GpioIrqConfig>,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "kebab-case", deny_unknown_fields)]
+struct GpioIrqConfig {
+    port: ConfigPort,
+    pin: u8,
+    owner: GpioIrqOwner,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "kebab-case", deny_unknown_fields)]
+struct GpioIrqOwner {
+    name: String,
+    notification: String,
+}
+
+#[derive(Copy, Clone, Debug, Deserialize)]
+enum ConfigPort {
+    A,
+    B,
+    C,
+    D,
+    E,
+    F,
+    G,
+    H,
+    I,
+    J,
+    K,
+}
+
+impl quote::ToTokens for ConfigPort {
+    fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
+        use proc_macro2::{Ident, Punct, Spacing, Span};
+        // i don't like typing
+        macro_rules! table {
+            ($($variant:ident),*) => {
+                match self {
+                    $(ConfigPort::$variant => {
+                        tokens.append(Ident::new("Port", Span::call_site()));
+                        tokens.append(Punct::new(':', Spacing::Joint));
+                        tokens.append(Punct::new(':', Spacing::Alone));
+                        tokens.append(Ident::new(stringify!($variant), Span::call_site()));
+                    }),*
+                }
+            }
+        }
+        table! { A, B, C, D, E, F, G, H, I, J, K }
+    }
+}
+
+impl SysConfig {
+    pub fn load() -> anyhow::Result<Self> {
+        Ok(build_util::config::<GlobalConfig>()?.sys)
+    }
+
+    pub fn needs_exti(&self) -> bool {
+        !self.gpio_irqs.is_empty()
+    }
+
+    pub fn generate_exti_config(
+        &self,
+    ) -> anyhow::Result<proc_macro2::TokenStream> {
+        #[derive(Debug)]
+        struct DispatchEntry<'a> {
+            _name: &'a str,
+            port: ConfigPort,
+            task: syn::Ident,
+            note: syn::Ident,
+        }
+
+        const NUM_EXTI_IRQS: usize = 16;
+        let mut dispatch_table: [Option<DispatchEntry<'_>>; NUM_EXTI_IRQS] =
+            Default::default();
+
+        for (
+            _name,
+            &GpioIrqConfig {
+                port,
+                pin,
+                ref owner,
+            },
+        ) in &self.gpio_irqs
+        {
+            match dispatch_table.get_mut(pin as usize) {
+                Some(Some(curr)) => {
+                    anyhow::bail!("pin {pin} is already mapped to IRQ {curr:?}")
+                }
+                Some(slot) => {
+                    let task = syn::parse_str(&owner.name)?;
+                    let note = quote::format_ident!(
+                        "{}_MASK",
+                        owner.notification.to_uppercase().replace('-', "_")
+                    );
+                    *slot = Some(DispatchEntry {
+                        _name,
+                        port,
+                        task,
+                        note,
+                    })
+                }
+                None => anyhow::bail!(
+                    "GPIO IRQ pin numbers must be < {NUM_EXTI_IRQS}; {pin} is out of range"
+                ),
+            }
+        }
+
+        let dispatches = dispatch_table.iter().map(|slot| match slot {
+            Some(DispatchEntry {
+                port, task, note, ..
+            }) => quote! {
+                Some((
+                    #port,
+                    userlib::TaskId::for_index_and_gen(
+                        hubris_num_tasks::Task::#task as usize,
+                        userlib::Generation::ZERO,
+                    ),
+                    crate::notifications::#task::#note,
+                ))
+            },
+            None => quote! { None },
+        });
+
+        Ok(quote! {
+            pub(crate) const EXTI_DISPATCH_TABLE: [Option<(Port, TaskId, u32)>; #NUM_EXTI_IRQS] = [
+                #( #dispatches ),*
+            ];
+        })
+    }
+}

drv/stm32xx-sys/Cargo.toml

@@ -22,6 +22,7 @@ zerocopy = { workspace = true }
 [build-dependencies]
 idol = { workspace = true }
 build-util = { path = "../../build/util" }
+build-stm32xx-sys = { path = "../../build/stm32xx-sys" }
 
 [features]
 family-stm32h7 = ["stm32h7", "drv-stm32xx-uid/family-stm32h7"]

drv/stm32xx-sys/build.rs

@@ -1,6 +1,7 @@
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
+use std::io::Write;
 
 fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
     build_util::build_notifications()?;
@@ -15,5 +16,24 @@ fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
             idol::server::ServerStyle::InOrder,
         )?;
 
+    let cfg = build_stm32xx_sys::SysConfig::load()?;
+
+    const EXTI_FEATURE: &str = "exti";
+
+    if build_util::has_feature(EXTI_FEATURE) {
+        let out_dir = build_util::out_dir();
+        let dest_path = out_dir.join("exti_config.rs");
+
+        let mut out = std::fs::File::create(dest_path)?;
+
+        let generated = cfg.generate_exti_config()?;
+        writeln!(out, "{generated}")?;
+    } else if cfg.needs_exti() {
+        return Err(format!(
+            "the \"drv-stm32xx-sys/{EXTI_FEATURE}\" feature is required in order to \
+            configure GPIO pin interrupts"
+        ).into());
+    }
+
     Ok(())
 }

drv/stm32xx-sys/src/main.rs

@@ -410,9 +410,9 @@ impl idl::InOrderSysImpl for ServerImpl<'_> {
 
                 for (i, entry) in generated::EXTI_DISPATCH_TABLE.iter().enumerate() {
                     // Only use populated rows in the table
-                    if let Some((_, tid, mask)) = entry {
+                    if let Some((_, task, mask)) = entry {
                         // Ignore anything assigned to another task
-                        if tid.index() == rm.sender.index() {
+                        if task.index() == rm.sender.index() {
                             // Apply disable first so that including the same
                             // thing in both masks is a no-op.
                             if mask & disable_mask != 0 {
@@ -870,31 +870,5 @@ mod idl {
 mod generated {
     use super::*;
 
-    // TODO: lol jk not really generated, written by hand
-    pub(super) static EXTI_DISPATCH_TABLE: [Option<(Port, TaskId, u32)>; 16] = [
-        None,
-        None,
-        None,
-        None,
-        None,
-        None,
-        None,
-        None,
-        None,
-        None,
-        None,
-        None,
-        None,
-        None,
-        // 14 - HACK HACK! This is PI14 on Gimlet for power system debugging
-        Some((
-            Port::I,
-            TaskId::for_index_and_gen(
-                hubris_num_tasks::Task::power as usize,
-                userlib::Generation::ZERO,
-            ),
-            1 << 1,
-        )),
-        None,
-    ];
+    include!(concat!(env!("OUT_DIR"), "/exti_config.rs"));
 }