chore(core/rust): Add IO module and polling function

core/embed/rust/src/io.rs

@@ -0,0 +1,89 @@
+use crate::{
+    error::Error,
+    time::{Duration, Instant},
+    trezorhal::usb::{usb_is_ready_to_read, usb_is_ready_to_write, IfaceTicket},
+    util::wait_in_busy_loop,
+};
+
+mod ffi {
+    extern "C" {
+        #[cfg(feature = "model_t1")]
+        pub fn button_read() -> u32;
+        #[cfg(feature = "model_tt")]
+        pub fn touch_read() -> u32;
+    }
+}
+
+#[cfg(feature = "model_t1")]
+pub fn button_read() -> u32 {
+    unsafe { ffi::button_read() }
+}
+
+#[cfg(feature = "model_tt")]
+pub fn touch_read() -> u32 {
+    unsafe { ffi::touch_read() }
+}
+
+pub enum Resource {
+    #[cfg(feature = "model_t1")]
+    Button,
+    #[cfg(feature = "model_tt")]
+    Touch,
+    UsbRead(IfaceTicket),
+    UsbWrite(IfaceTicket),
+}
+
+pub enum Event {
+    #[cfg(feature = "model_t1")]
+    Button(u32), // TODO: We should somehow use `ButtonEvent` from UI here.
+    #[cfg(feature = "model_tt")]
+    Touch(u32), // TODO: We should somehow use `TouchEvent` from UI here.
+    UsbRead(IfaceTicket),
+    UsbWrite(IfaceTicket),
+    TimedOut,
+}
+
+pub fn poll_io(resources: &[Resource], timeout: Duration) -> Result<Event, Error> {
+    let deadline = Instant::now()
+        .checked_add(timeout)
+        .ok_or(Error::OutOfRange)?;
+
+    loop {
+        // Poll all resources, return if ready.
+        for &resource in resources {
+            match resource {
+                #[cfg(feature = "model_t1")]
+                Resource::Button => {
+                    let event = button_read();
+                    if event != 0 {
+                        return Ok(Event::Button(event));
+                    }
+                }
+                #[cfg(feature = "model_tt")]
+                Resource::Touch => {
+                    let event = touch_read();
+                    if event != 0 {
+                        return Ok(Event::Touch(event));
+                    }
+                }
+                Resource::UsbRead(ticket) => {
+                    if usb_is_ready_to_read(ticket) {
+                        return Ok(Event::UsbRead(ticket));
+                    }
+                }
+                Resource::UsbWrite(ticket) => {
+                    if usb_is_ready_to_write(ticket) {
+                        return Ok(Event::UsbWrite(ticket));
+                    }
+                }
+            }
+        }
+
+        // No resource is ready yet, wait or exit on timeout.
+        if Instant::now() < deadline {
+            wait_in_busy_loop();
+        } else {
+            return Ok(Event::TimedOut);
+        }
+    }
+}

core/embed/rust/src/lib.rs

@@ -16,6 +16,7 @@ mod trezorhal;
 #[cfg(feature = "ui")]
 #[macro_use]
 mod ui;
+mod io;
 mod util;
 
 #[cfg(not(feature = "test"))]

core/embed/rust/src/trezorhal/usb.rs

@@ -13,20 +13,6 @@ pub enum UsbError {
     InterfaceNotFound,
 }
 
-pub enum Interest {
-    /// Caller is interested to read bytes/messages.
-    Read,
-    /// Caller is interested to write bytes/messages.
-    Write,
-}
-
-pub enum Event {
-    /// Resource is ready to perform on selected `Interest`.
-    Ready,
-    /// Resource is not yet ready. No side-effect was performed.
-    Pending,
-}
-
 /// Initialize the USB stack with information from `config`, register all
 /// present USB interfaces, and start the communication.
 ///
@@ -60,24 +46,23 @@ pub fn usb_open(mut config: UsbConfig) -> Result<(), UsbError> {
     Ok(())
 }
 
-/// Check if interface `ticket` is ready to perform on selected `interest`.
+/// Check if interface `ticket` is ready to read a report.
 ///
 /// Returns immediately, does not block. Useful for constructing event loops.
-pub fn usb_poll(ticket: IfaceTicket, interest: Interest) -> Event {
-    let ready = match ticket {
-        IfaceTicket::Hid(iface_num) => match interest {
-            Interest::Read => HidConfig::ready_to_read(iface_num),
-            Interest::Write => HidConfig::ready_to_write(iface_num),
-        },
-        IfaceTicket::WebUsb(iface_num) => match interest {
-            Interest::Read => WebUsbConfig::ready_to_read(iface_num),
-            Interest::Write => WebUsbConfig::ready_to_write(iface_num),
-        },
-    };
-    if ready {
-        Event::Ready
-    } else {
-        Event::Pending
+pub fn usb_is_ready_to_read(ticket: IfaceTicket) -> bool {
+    match ticket {
+        IfaceTicket::Hid(iface_num) => HidConfig::ready_to_read(iface_num),
+        IfaceTicket::WebUsb(iface_num) => WebUsbConfig::ready_to_read(iface_num),
+    }
+}
+
+/// Check if interface `ticket` is ready to write a report.
+///
+/// Returns immediately, does not block. Useful for constructing event loops.
+pub fn usb_is_ready_to_write(ticket: IfaceTicket) -> bool {
+    match ticket {
+        IfaceTicket::Hid(iface_num) => HidConfig::ready_to_write(iface_num),
+        IfaceTicket::WebUsb(iface_num) => WebUsbConfig::ready_to_write(iface_num),
     }
 }
 

core/embed/rust/src/util.rs

@@ -1,5 +1,7 @@
 use core::slice;
 
+use crate::micropython::time;
+use crate::time::Duration;
 use crate::{
     error::Error,
     micropython::{
@@ -9,6 +11,22 @@ use crate::{
     },
 };
 
+/// Wait an unspecified short amount of time. To be used in busy loops.
+pub fn wait_in_busy_loop() {
+    match () {
+        #[cfg(cortex_m)]
+        () => {
+            // In device context, run the WFI instruction.
+            unsafe { asm!("wfi" :::: "volatile") }
+        }
+        #[cfg(not(cortex_m))]
+        () => {
+            // In desktop context, we sleep for 1ms.
+            time::sleep(Duration::from_millis(1))
+        }
+    }
+}
+
 /// Perform a call and convert errors into a raised MicroPython exception.
 /// Should only called when returning from Rust to C. See `raise_exception` for
 /// details.