Add a basic blocking QSPI interface

This module implements the QuadSPI interface which allows high speed
communication with external flash memory.

Limitations
    - Interrupts are not supported.
    - Status polling mode is not supported.

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 
  - Extended 64-bit monotonic timer [#640]
+ - Basic blocking QSPI interface [#645]
 
 ### Fixed
 
@@ -26,6 +27,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 [#635]: https://github.com/stm32-rs/stm32f4xx-hal/pull/635
 [#636]: https://github.com/stm32-rs/stm32f4xx-hal/pull/636
 [#640]: https://github.com/stm32-rs/stm32f4xx-hal/pull/640
+[#645]: https://github.com/stm32-rs/stm32f4xx-hal/pull/645
 
 ## [v0.16.0] - 2023-05-07
 

src/gpio/alt.rs

@@ -368,11 +368,11 @@ pub trait QuadSpiBanks {
 }
 #[cfg(feature = "quadspi")]
 pub trait QuadSpiBank {
-    type Io0;
-    type Io1;
-    type Io2;
-    type Io3;
-    type Ncs;
+    type Io0: crate::gpio::PinSpeed;
+    type Io1: crate::gpio::PinSpeed;
+    type Io2: crate::gpio::PinSpeed;
+    type Io3: crate::gpio::PinSpeed;
+    type Ncs: crate::gpio::PinSpeed;
 }
 
 // SAI pins

src/lib.rs

@@ -153,6 +153,8 @@ pub mod fsmc_lcd;
 pub mod prelude;
 #[cfg(feature = "device-selected")]
 pub mod qei;
+#[cfg(feature = "quadspi")]
+pub mod qspi;
 #[cfg(feature = "device-selected")]
 pub mod rcc;
 #[cfg(feature = "device-selected")]