Merge #601

601: [part 1/n] Change macrotables to build.rs codegen r=lulf a=Dirbaio

This PR replaces the "macrotables" (the macros like `stm32_data::peripherals!`) with a `const METADATA`.

Macrotables had some problems:

- Hard to debug
- Somewhat footgunny (typo the "pattern" and then nothing matches and the macro now expands to nothing, silently!)
- Limited power
  - Can't count, so we had to add a [special macrotable for that](https://github.com/embassy-rs/embassy/blob/f50f3f0a73a41275e6ea21d8661081acad381e05/embassy-stm32/src/dma/bdma.rs#L26).
  - Can't remove duplicates, so we had to fallback to [Rust code in build.rs](https://github.com/embassy-rs/embassy/blob/f50f3f0a73a41275e6ea21d8661081acad381e05/embassy-stm32/build.rs#L105-L145)
  - Can't include the results as a listto another macro, so again [build.rs](https://github.com/embassy-rs/embassy/blob/master/embassy-stm32/build.rs#L100-L101).

They work fine for the 95% of cases, but for the remaining 5% we need Rust code in build.rs. So we might as well do everything with Rust code, so everything is consistent.

The new approach generates a `const METADATA: Metadata = Metadata { ... }` with [these structs](https://github.com/embassy-rs/embassy/blob/unmacrotablize/stm32-metapac-gen/src/assets/metadata.rs) in `stm32-metapac`. `build.rs` can then read that and generate whatever code.


Co-authored-by: Dario Nieuwenhuis <[email protected]>

12 files changed, 363 insertions, 239 deletions

diff --git a/embassy-stm32/Cargo.toml b/embassy-stm32/Cargo.toml
index ebd62cbf7..386722d47 100644
--- a/embassy-stm32/Cargo.toml
+++ b/embassy-stm32/Cargo.toml
@@ -36,7 +36,9 @@ seq-macro = "0.2.2"
 cfg-if = "1.0.0"
 
 [build-dependencies]
-stm32-metapac = { version = "0.1.0", path = "../stm32-metapac", default-features = false }
+proc-macro2 = "1.0.36"
+quote = "1.0.15"
+stm32-metapac = { version = "0.1.0", path = "../stm32-metapac", default-features = false, features = ["metadata"]}
 
 [features]
 sdmmc-rs = ["embedded-sdmmc"]
diff --git a/embassy-stm32/build.rs b/embassy-stm32/build.rs
index aee596445..6bef745f1 100644
--- a/embassy-stm32/build.rs
+++ b/embassy-stm32/build.rs
@@ -1,8 +1,10 @@
-use std::collections::HashMap;
+use proc_macro2::TokenStream;
+use quote::{format_ident, quote};
+use std::collections::HashSet;
 use std::env;
-use std::fmt::Write;
 use std::fs;
 use std::path::PathBuf;
+use stm32_metapac::metadata::METADATA;
 
 fn main() {
     let chip_name = match env::vars()
@@ -18,67 +20,50 @@ fn main() {
     .unwrap()
     .to_ascii_lowercase();
 
-    struct Peripheral {
-        kind: String,
-        name: String,
-        version: String,
+    for p in METADATA.peripherals {
+        if let Some(r) = &p.registers {
+            println!("cargo:rustc-cfg={}", r.kind);
+            println!("cargo:rustc-cfg={}_{}", r.kind, r.version);
+        }
     }
 
-    let mut peripheral_version_mapping = HashMap::<String, String>::new();
-    stm32_metapac::peripheral_versions!(
-        ($peri:ident, $version:ident) => {
-            peripheral_version_mapping.insert(stringify!($peri).to_string(), stringify!($version).to_string());
-            println!("cargo:rustc-cfg={}", stringify!($peri));
-            println!("cargo:rustc-cfg={}_{}", stringify!($peri), stringify!($version));
-        };
-    );
-
-    let mut peripherals: Vec<Peripheral> = Vec::new();
-    stm32_metapac::peripherals!(
-        ($kind:ident, $name:ident) => {
-            peripherals.push(Peripheral{
-                kind: stringify!($kind).to_string(),
-                name: stringify!($name).to_string(),
-                version: peripheral_version_mapping[&stringify!($kind).to_ascii_lowercase()].clone()
-            });
-        };
-    );
-
     // ========
     // Generate singletons
 
     let mut singletons: Vec<String> = Vec::new();
-    for p in peripherals {
-        match p.kind.as_str() {
-            // Generate singletons per pin, not per port
-            "gpio" => {
-                println!("{}", p.name);
-                let port_letter = p.name.strip_prefix("GPIO").unwrap();
-                for pin_num in 0..16 {
-                    singletons.push(format!("P{}{}", port_letter, pin_num));
+    for p in METADATA.peripherals {
+        if let Some(r) = &p.registers {
+            match r.kind {
+                // Generate singletons per pin, not per port
+                "gpio" => {
+                    println!("{}", p.name);
+                    let port_letter = p.name.strip_prefix("GPIO").unwrap();
+                    for pin_num in 0..16 {
+                        singletons.push(format!("P{}{}", port_letter, pin_num));
+                    }
                 }
-            }
-
-            // No singleton for these, the HAL handles them specially.
-            "exti" => {}
 
-            // We *shouldn't* have singletons for these, but the HAL currently requires
-            // singletons, for using with RccPeripheral to enable/disable clocks to them.
-            "rcc" => {
-                if p.version == "h7" {
-                    singletons.push("MCO1".to_string());
-                    singletons.push("MCO2".to_string());
+                // No singleton for these, the HAL handles them specially.
+                "exti" => {}
+
+                // We *shouldn't* have singletons for these, but the HAL currently requires
+                // singletons, for using with RccPeripheral to enable/disable clocks to them.
+                "rcc" => {
+                    if r.version == "h7" {
+                        singletons.push("MCO1".to_string());
+                        singletons.push("MCO2".to_string());
+                    }
+                    singletons.push(p.name.to_string());
                 }
-                singletons.push(p.name.clone());
+                //"dbgmcu" => {}
+                //"syscfg" => {}
+                //"dma" => {}
+                //"bdma" => {}
+                //"dmamux" => {}
+
+                // For other peripherals, one singleton per peri
+                _ => singletons.push(p.name.to_string()),
             }
-            //"dbgmcu" => {}
-            //"syscfg" => {}
-            //"dma" => {}
-            //"bdma" => {}
-            //"dmamux" => {}
-
-            // For other peripherals, one singleton per peri
-            _ => singletons.push(p.name.clone()),
         }
     }
 
@@ -88,60 +73,161 @@ fn main() {
     }
 
     // One singleton per DMA channel
-    stm32_metapac::dma_channels! {
-        ($channel_peri:ident, $dma_peri:ident, $version:ident, $channel_num:expr, $ignore:tt) => {
-            singletons.push(stringify!($channel_peri).to_string());
-        };
+    for c in METADATA.dma_channels {
+        singletons.push(c.name.to_string());
+    }
+
+    let mut g = TokenStream::new();
+
+    let singleton_tokens: Vec<_> = singletons.iter().map(|s| format_ident!("{}", s)).collect();
+    g.extend(quote! {
+        embassy_hal_common::peripherals!(#(#singleton_tokens),*);
+    });
+
+    // ========
+    // Generate interrupt declarations
+
+    let mut irqs = Vec::new();
+    for irq in METADATA.interrupts {
+        irqs.push(format_ident!("{}", irq.name));
     }
 
-    let mut generated = String::new();
-    write!(
-        &mut generated,
-        "embassy_hal_common::peripherals!({});\n",
-        singletons.join(",")
-    )
-    .unwrap();
+    g.extend(quote! {
+        pub mod interrupt {
+            use crate::pac::Interrupt as InterruptEnum;
+            #(
+                embassy::interrupt::declare!(#irqs);
+            )*
+        }
+    });
 
     // ========
     // Generate DMA IRQs.
-    // This can't be done with macrotables alone because in many chips, one irq is shared between many
-    // channels, so we have to deduplicate them.
-
-    #[allow(unused_mut)]
-    let mut dma_irqs: Vec<String> = Vec::new();
-    #[allow(unused_mut)]
-    let mut bdma_irqs: Vec<String> = Vec::new();
-
-    stm32_metapac::interrupts! {
-        ($peri:ident, dma, $block:ident, $signal_name:ident, $irq:ident) => {
-            dma_irqs.push(stringify!($irq).to_string());
-        };
-        ($peri:ident, bdma, $block:ident, $signal_name:ident, $irq:ident) => {
-            bdma_irqs.push(stringify!($irq).to_string());
-        };
+
+    let mut dma_irqs: HashSet<&str> = HashSet::new();
+    let mut bdma_irqs: HashSet<&str> = HashSet::new();
+
+    for p in METADATA.peripherals {
+        if let Some(r) = &p.registers {
+            match r.kind {
+                "dma" => {
+                    for irq in p.interrupts {
+                        dma_irqs.insert(irq.interrupt);
+                    }
+                }
+                "bdma" => {
+                    for irq in p.interrupts {
+                        bdma_irqs.insert(irq.interrupt);
+                    }
+                }
+                _ => {}
+            }
+        }
     }
 
-    dma_irqs.sort();
-    dma_irqs.dedup();
-    bdma_irqs.sort();
-    bdma_irqs.dedup();
-
-    for irq in dma_irqs {
-        write!(
-            &mut generated,
-            "#[crate::interrupt] unsafe fn {} () {{ crate::dma::dma::on_irq(); }}\n",
-            irq
-        )
-        .unwrap();
+    let tokens: Vec<_> = dma_irqs.iter().map(|s| format_ident!("{}", s)).collect();
+    g.extend(quote! {
+        #(
+            #[crate::interrupt]
+            unsafe fn #tokens () {
+                crate::dma::dma::on_irq();
+            }
+        )*
+    });
+
+    let tokens: Vec<_> = bdma_irqs.iter().map(|s| format_ident!("{}", s)).collect();
+    g.extend(quote! {
+        #(
+            #[crate::interrupt]
+            unsafe fn #tokens () {
+                crate::dma::bdma::on_irq();
+            }
+        )*
+    });
+
+    // ========
+    // Generate RccPeripheral impls
+
+    for p in METADATA.peripherals {
+        if !singletons.contains(&p.name.to_string()) {
+            continue;
+        }
+
+        if let Some(rcc) = &p.rcc {
+            let en = rcc.enable.as_ref().unwrap();
+
+            let rst = match &rcc.reset {
+                Some(rst) => {
+                    let rst_reg = format_ident!("{}", rst.register.to_ascii_lowercase());
+                    let set_rst_field = format_ident!("set_{}", rst.field.to_ascii_lowercase());
+                    quote! {
+                        critical_section::with(|_| unsafe {
+                            crate::pac::RCC.#rst_reg().modify(|w| w.#set_rst_field(true));
+                            crate::pac::RCC.#rst_reg().modify(|w| w.#set_rst_field(false));
+                        });
+                    }
+                }
+                None => TokenStream::new(),
+            };
+
+            let pname = format_ident!("{}", p.name);
+            let clk = format_ident!("{}", rcc.clock.to_ascii_lowercase());
+            let en_reg = format_ident!("{}", en.register.to_ascii_lowercase());
+            let set_en_field = format_ident!("set_{}", en.field.to_ascii_lowercase());
+
+            g.extend(quote! {
+                impl crate::rcc::sealed::RccPeripheral for peripherals::#pname {
+                    fn frequency() -> crate::time::Hertz {
+                        critical_section::with(|_| unsafe {
+                            crate::rcc::get_freqs().#clk
+                        })
+                    }
+                    fn enable() {
+                        critical_section::with(|_| unsafe {
+                            crate::pac::RCC.#en_reg().modify(|w| w.#set_en_field(true))
+                        })
+                    }
+                    fn disable() {
+                        critical_section::with(|_| unsafe {
+                            crate::pac::RCC.#en_reg().modify(|w| w.#set_en_field(false));
+                        })
+                    }
+                    fn reset() {
+                        #rst
+                    }
+                }
+
+                impl crate::rcc::RccPeripheral for peripherals::#pname {}
+            });
+        }
     }
 
-    for irq in bdma_irqs {
-        write!(
-            &mut generated,
-            "#[crate::interrupt] unsafe fn {} () {{ crate::dma::bdma::on_irq(); }}\n",
-            irq
-        )
-        .unwrap();
+    // ========
+    // Generate fns to enable GPIO, DMA in RCC
+
+    for kind in ["dma", "bdma", "dmamux", "gpio"] {
+        let mut gg = TokenStream::new();
+
+        for p in METADATA.peripherals {
+            if p.registers.is_some() && p.registers.as_ref().unwrap().kind == kind {
+                if let Some(rcc) = &p.rcc {
+                    let en = rcc.enable.as_ref().unwrap();
+                    let en_reg = format_ident!("{}", en.register.to_ascii_lowercase());
+                    let set_en_field = format_ident!("set_{}", en.field.to_ascii_lowercase());
+
+                    gg.extend(quote! {
+                        crate::pac::RCC.#en_reg().modify(|w| w.#set_en_field(true));
+                    })
+                }
+            }
+        }
+
+        let fname = format_ident!("init_{}", kind);
+        g.extend(quote! {
+            pub unsafe fn #fname(){
+                #gg
+            }
+        })
     }
 
     // ========
@@ -149,7 +235,7 @@ fn main() {
 
     let out_dir = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
     let out_file = out_dir.join("generated.rs").to_string_lossy().to_string();
-    fs::write(out_file, &generated).unwrap();
+    fs::write(out_file, g.to_string()).unwrap();
 
     // ========
     // Multicore
diff --git a/embassy-stm32/src/dma/bdma.rs b/embassy-stm32/src/dma/bdma.rs
index ebb0467dc..a37de2d63 100644
--- a/embassy-stm32/src/dma/bdma.rs
+++ b/embassy-stm32/src/dma/bdma.rs
@@ -9,7 +9,6 @@ use embassy::waitqueue::AtomicWaker;
 use crate::dma::Request;
 use crate::pac;
 use crate::pac::bdma::vals;
-use crate::rcc::sealed::RccPeripheral;
 
 use super::{Word, WordSize};
 
@@ -77,11 +76,7 @@ pub(crate) unsafe fn init() {
             crate::interrupt::$irq::steal().enable();
         };
     }
-    pac::peripherals! {
-        (bdma, $peri:ident) => {
-            crate::peripherals::$peri::enable();
-        };
-    }
+    crate::generated::init_bdma();
 }
 
 pac::dma_channels! {
diff --git a/embassy-stm32/src/dma/dma.rs b/embassy-stm32/src/dma/dma.rs
index 21623b90c..c885452b0 100644
--- a/embassy-stm32/src/dma/dma.rs
+++ b/embassy-stm32/src/dma/dma.rs
@@ -7,7 +7,6 @@ use embassy::waitqueue::AtomicWaker;
 use crate::interrupt;
 use crate::pac;
 use crate::pac::dma::{regs, vals};
-use crate::rcc::sealed::RccPeripheral;
 
 use super::{Request, Word, WordSize};
 
@@ -74,11 +73,7 @@ pub(crate) unsafe fn init() {
             interrupt::$irq::steal().enable();
         };
     }
-    pac::peripherals! {
-        (dma, $peri:ident) => {
-            crate::peripherals::$peri::enable();
-        };
-    }
+    crate::generated::init_dma();
 }
 
 pac::dma_channels! {
diff --git a/embassy-stm32/src/dma/dmamux.rs b/embassy-stm32/src/dma/dmamux.rs
index 83dcff4e8..fd076581b 100644
--- a/embassy-stm32/src/dma/dmamux.rs
+++ b/embassy-stm32/src/dma/dmamux.rs
@@ -49,11 +49,5 @@ pac::dma_channels! {
 
 /// safety: must be called only once
 pub(crate) unsafe fn init() {
-    crate::pac::peripheral_rcc! {
-        ($name:ident, dmamux, DMAMUX, $clock:ident, ($reg:ident, $field:ident, $set_field:ident), $rst:tt) => {
-            crate::pac::RCC.$reg().modify(|reg| {
-                reg.$set_field(true);
-            });
-        };
-    }
+    crate::generated::init_dmamux();
 }
diff --git a/embassy-stm32/src/gpio.rs b/embassy-stm32/src/gpio.rs
index d4606716c..f154a66c4 100644
--- a/embassy-stm32/src/gpio.rs
+++ b/embassy-stm32/src/gpio.rs
@@ -608,13 +608,7 @@ crate::pac::pins!(
 );
 
 pub(crate) unsafe fn init() {
-    crate::pac::peripheral_rcc! {
-        ($name:ident, gpio, GPIO, $clock:ident, ($reg:ident, $field:ident, $set_field:ident), $rst:tt) => {
-            crate::pac::RCC.$reg().modify(|reg| {
-                reg.$set_field(true);
-            });
-        };
-    }
+    crate::generated::init_gpio();
 }
 
 mod eh02 {
diff --git a/embassy-stm32/src/interrupt.rs b/embassy-stm32/src/interrupt.rs
index 27e441644..c757b790c 100644
--- a/embassy-stm32/src/interrupt.rs
+++ b/embassy-stm32/src/interrupt.rs
@@ -3,11 +3,4 @@ pub use critical_section::CriticalSection;
 pub use embassy::interrupt::{take, Interrupt};
 pub use embassy_hal_common::interrupt::Priority4 as Priority;
 
-use crate::pac::Interrupt as InterruptEnum;
-use embassy::interrupt::declare;
-
-crate::pac::interrupts!(
-    ($name:ident) => {
-        declare!($name);
-    };
-);
+pub use crate::generated::interrupt::*;
diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index 4bc044047..a910f6950 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -65,8 +65,6 @@ mod generated {
     #![allow(unused_imports)]
     #![allow(non_snake_case)]
 
-    use crate::interrupt;
-
     include!(concat!(env!("OUT_DIR"), "/generated.rs"));
 }
 pub use embassy_macros::interrupt;
diff --git a/embassy-stm32/src/rcc/mod.rs b/embassy-stm32/src/rcc/mod.rs
index 541d9c148..3aab01afd 100644
--- a/embassy-stm32/src/rcc/mod.rs
+++ b/embassy-stm32/src/rcc/mod.rs
@@ -1,6 +1,5 @@
 #![macro_use]
 
-use crate::peripherals;
 use crate::time::Hertz;
 use core::mem::MaybeUninit;
 
@@ -104,66 +103,3 @@ pub(crate) mod sealed {
 }
 
 pub trait RccPeripheral: sealed::RccPeripheral + 'static {}
-
-crate::pac::peripheral_rcc!(
-    ($inst:ident, gpio, GPIO, $clk:ident, $en:tt, $rst:tt) => {};
-    ($inst:ident, $module:ident, $block:ident, $clk:ident, ($en_reg:ident, $en_field:ident, $en_set_field:ident), ($rst_reg:ident, $rst_field:ident, $rst_set_field:ident)) => {
-        impl sealed::RccPeripheral for peripherals::$inst {
-            fn frequency() -> crate::time::Hertz {
-                critical_section::with(|_| {
-                    unsafe { get_freqs().$clk }
-                })
-            }
-            fn enable() {
-                critical_section::with(|_| {
-                    unsafe {
-                        crate::pac::RCC.$en_reg().modify(|w| w.$en_set_field(true));
-                    }
-                })
-            }
-            fn disable() {
-                critical_section::with(|_| {
-                    unsafe {
-                        crate::pac::RCC.$en_reg().modify(|w| w.$en_set_field(false));
-                    }
-                })
-            }
-            fn reset() {
-                critical_section::with(|_| {
-                    unsafe {
-                        crate::pac::RCC.$rst_reg().modify(|w| w.$rst_set_field(true));
-                        crate::pac::RCC.$rst_reg().modify(|w| w.$rst_set_field(false));
-                    }
-                })
-            }
-        }
-
-        impl RccPeripheral for peripherals::$inst {}
-    };
-    ($inst:ident, $module:ident, $block:ident, $clk:ident, ($en_reg:ident, $en_field:ident, $en_set_field:ident), _) => {
-        impl sealed::RccPeripheral for peripherals::$inst {
-            fn frequency() -> crate::time::Hertz {
-                critical_section::with(|_| {
-                    unsafe { get_freqs().$clk }
-                })
-            }
-            fn enable() {
-                critical_section::with(|_| {
-                    unsafe {
-                        crate::pac::RCC.$en_reg().modify(|w| w.$en_set_field(true));
-                    }
-                })
-            }
-            fn disable() {
-                critical_section::with(|_| {
-                    unsafe {
-                        crate::pac::RCC.$en_reg().modify(|w| w.$en_set_field(false));
-                    }
-                })
-            }
-            fn reset() {}
-        }
-
-        impl RccPeripheral for peripherals::$inst {}
-    };
-);
diff --git a/stm32-metapac-gen/src/assets/metadata.rs b/stm32-metapac-gen/src/assets/metadata.rs
new file mode 100644
index 000000000..7fe49ceba
--- /dev/null
+++ b/stm32-metapac-gen/src/assets/metadata.rs
@@ -0,0 +1,97 @@
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct Metadata {
+    pub name: &'static str,
+    pub family: &'static str,
+    pub line: &'static str,
+    pub memory: &'static [MemoryRegion],
+    pub peripherals: &'static [Peripheral],
+    pub interrupts: &'static [Interrupt],
+    pub dma_channels: &'static [DmaChannel],
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct MemoryRegion {
+    pub name: &'static str,
+    pub kind: MemoryRegionKind,
+    pub address: u32,
+    pub size: u32,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub enum MemoryRegionKind {
+    Flash,
+    Ram,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct Interrupt {
+    pub name: &'static str,
+    pub number: u32,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct Package {
+    pub name: &'static str,
+    pub package: &'static str,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct Peripheral {
+    pub name: &'static str,
+    pub address: u64,
+    pub registers: Option<PeripheralRegisters>,
+    pub rcc: Option<PeripheralRcc>,
+    pub pins: &'static [PeripheralPin],
+    pub dma_channels: &'static [PeripheralDmaChannel],
+    pub interrupts: &'static [PeripheralInterrupt],
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct PeripheralRegisters {
+    pub kind: &'static str,
+    pub version: &'static str,
+    pub block: &'static str,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct PeripheralInterrupt {
+    pub signal: &'static str,
+    pub interrupt: &'static str,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct PeripheralRcc {
+    pub clock: &'static str,
+    pub enable: Option<PeripheralRccRegister>,
+    pub reset: Option<PeripheralRccRegister>,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct PeripheralRccRegister {
+    pub register: &'static str,
+    pub field: &'static str,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct PeripheralPin {
+    pub pin: &'static str,
+    pub signal: &'static str,
+    pub af: Option<&'static str>,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct DmaChannel {
+    pub name: &'static str,
+    pub dma: &'static str,
+    pub channel: u32,
+    pub dmamux: Option<&'static str>,
+    pub dmamux_channel: Option<u32>,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct PeripheralDmaChannel {
+    pub signal: &'static str,
+    pub channel: Option<&'static str>,
+    pub dmamux: Option<&'static str>,
+    pub request: Option<u32>,
+}
diff --git a/stm32-metapac-gen/src/lib.rs b/stm32-metapac-gen/src/lib.rs
index fd8da8a6f..10d67869a 100644
--- a/stm32-metapac-gen/src/lib.rs
+++ b/stm32-metapac-gen/src/lib.rs
@@ -16,6 +16,17 @@ use chiptool::{generate, ir, transform};
 mod data;
 use data::*;
 
+#[derive(Debug, Eq, PartialEq, Clone)]
+struct Metadata<'a> {
+    name: &'a str,
+    family: &'a str,
+    line: &'a str,
+    memory: &'a [MemoryRegion],
+    peripherals: &'a [Peripheral],
+    interrupts: &'a [Interrupt],
+    dma_channels: &'a [DmaChannel],
+}
+
 fn make_peripheral_counts(out: &mut String, data: &BTreeMap<String, u8>) {
     write!(
         out,
@@ -115,7 +126,6 @@ pub fn gen_chip(
     let mut interrupt_table: Vec<Vec<String>> = Vec::new();
     let mut peripherals_table: Vec<Vec<String>> = Vec::new();
     let mut peripheral_pins_table: Vec<Vec<String>> = Vec::new();
-    let mut peripheral_rcc_table: Vec<Vec<String>> = Vec::new();
     let mut dma_channels_table: Vec<Vec<String>> = Vec::new();
     let mut peripheral_dma_channels_table: Vec<Vec<String>> = Vec::new();
     let mut peripheral_counts: BTreeMap<String, u8> = BTreeMap::new();
@@ -253,34 +263,6 @@ pub fn gen_chip(
                 }
                 _ => {}
             }
-
-            if let Some(rcc) = &p.rcc {
-                let mut clock = rcc.clock.to_ascii_lowercase();
-                if p.name.starts_with("TIM") {
-                    clock = format!("{}_tim", clock)
-                }
-
-                let mut row = Vec::new();
-                row.push(p.name.clone());
-                row.push(bi.kind.clone());
-                row.push(bi.block.clone());
-                row.push(clock);
-
-                for reg in [&rcc.enable, &rcc.reset] {
-                    if let Some(reg) = reg {
-                        row.push(format!(
-                            "({}, {}, set_{})",
-                            reg.register.to_ascii_lowercase(),
-                            reg.field.to_ascii_lowercase(),
-                            reg.field.to_ascii_lowercase()
-                        ));
-                    } else {
-                        row.push("_".to_string())
-                    }
-                }
-
-                peripheral_rcc_table.push(row);
-            }
         }
 
         dev.peripherals.push(ir_peri);
@@ -384,12 +366,7 @@ pub fn gen_chip(
     let mut device_x = String::new();
 
     for irq in &core.interrupts {
-        write!(
-            &mut device_x,
-            "PROVIDE({} = DefaultHandler);\n",
-            irq.name.to_ascii_uppercase()
-        )
-        .unwrap();
+        write!(&mut device_x, "PROVIDE({} = DefaultHandler);\n", irq.name).unwrap();
     }
 
     // ==============================
@@ -397,6 +374,7 @@ pub fn gen_chip(
 
     let mut data = String::new();
 
+    write!(&mut data, "#[cfg(feature=\"metadata\")] pub mod metadata;").unwrap();
     write!(&mut data, "#[cfg(feature=\"pac\")] mod pac;").unwrap();
     write!(&mut data, "#[cfg(feature=\"pac\")] pub use pac::*; ").unwrap();
 
@@ -415,7 +393,6 @@ pub fn gen_chip(
         "peripheral_dma_channels",
         &peripheral_dma_channels_table,
     );
-    make_table(&mut data, "peripheral_rcc", &peripheral_rcc_table);
     make_table(&mut data, "dma_channels", &dma_channels_table);
     make_table(&mut data, "dbgmcu", &dbgmcu_table);
     make_peripheral_counts(&mut data, &peripheral_counts);
@@ -425,6 +402,38 @@ pub fn gen_chip(
     file.write_all(data.as_bytes()).unwrap();
 
     // ==============================
+    // generate metadata.rs
+
+    let metadata = Metadata {
+        name: &chip.name,
+        family: &chip.family,
+        line: &chip.line,
+        memory: &chip.memory,
+        peripherals: &core.peripherals,
+        interrupts: &core.interrupts,
+        dma_channels: &core.dma_channels,
+    };
+    let metadata = format!("{:#?}", metadata);
+    let metadata = metadata.replace("[\n", "&[\n");
+    let metadata = metadata.replace("[],\n", "&[],\n");
+
+    let mut data = String::new();
+
+    write!(
+        &mut data,
+        "
+            include!(\"../../metadata.rs\");
+            use MemoryRegionKind::*;
+            pub const METADATA: Metadata = {};    
+        ",
+        metadata
+    )
+    .unwrap();
+
+    let mut file = File::create(chip_dir.join("metadata.rs")).unwrap();
+    file.write_all(data.as_bytes()).unwrap();
+
+    // ==============================
     // generate device.x
 
     File::create(chip_dir.join("device.x"))
@@ -462,7 +471,21 @@ pub fn gen(options: Options) {
     for chip_name in &options.chips {
         println!("Generating {}...", chip_name);
 
-        let chip = load_chip(&options, chip_name);
+        let mut chip = load_chip(&options, chip_name);
+
+        // Cleanup
+        for core in &mut chip.cores {
+            for irq in &mut core.interrupts {
+                irq.name = irq.name.to_ascii_uppercase();
+            }
+            for p in &mut core.peripherals {
+                for irq in &mut p.interrupts {
+                    irq.interrupt = irq.interrupt.to_ascii_uppercase();
+                }
+            }
+        }
+
+        // Generate
         for (core_index, core) in chip.cores.iter().enumerate() {
             let chip_core_name = match chip.cores.len() {
                 1 => chip_name.clone(),
@@ -557,6 +580,13 @@ pub fn gen(options: Options) {
     )
     .unwrap();
 
+    // Generate src/metadata.rs
+    fs::write(
+        options.out_dir.join("src").join("metadata.rs"),
+        include_bytes!("assets/metadata.rs"),
+    )
+    .unwrap();
+
     // Generate Cargo.toml
     const BUILDDEP_BEGIN: &[u8] = b"# BEGIN BUILD DEPENDENCIES";
     const BUILDDEP_END: &[u8] = b"# END BUILD DEPENDENCIES";
diff --git a/stm32-metapac/Cargo.toml b/stm32-metapac/Cargo.toml
index 4115da349..5642af46e 100644
--- a/stm32-metapac/Cargo.toml
+++ b/stm32-metapac/Cargo.toml
@@ -19,10 +19,14 @@ regex = "1.5.4"
 default = ["pac"]
 
 # Build the actual PAC. Set by default.
-# If not set, only the macrotables will be generated. You may want to not set it
-# if you're using stm32-metapac from a build.rs script to use the macros.
+# If you just want the metadata, unset it with `default-features = false`. 
 pac = []
 
+# Build the chip metadata.
+# If set, a const `stm32_metapac::METADATA` will be exported, containing all the 
+# metadata for the currently selected chip.
+metadata = []
+
 rt = ["cortex-m-rt/device"]
 memory-x = []