Merge branch 'main' into 17-add-support-for-boot-protocol

2 files changed, 35 insertions, 11 deletions

diff --git a/embassy-rp/src/lib.rs b/embassy-rp/src/lib.rs
index 6fb680b34..d03ba1fef 100644
--- a/embassy-rp/src/lib.rs
+++ b/embassy-rp/src/lib.rs
@@ -565,18 +565,10 @@ unsafe fn install_stack_guard(stack_bottom: *mut usize) -> Result<(), ()> {
 #[cfg(all(feature = "_rp235x", not(feature = "_test")))]
 #[inline(always)]
 unsafe fn install_stack_guard(stack_bottom: *mut usize) -> Result<(), ()> {
-    let core = unsafe { cortex_m::Peripherals::steal() };
+    // The RP2350 arm cores are cortex-m33 and can use the MSPLIM register to guard the end of stack.
+    // We'll need to do something else for the riscv cores.
+    cortex_m::register::msplim::write(stack_bottom.addr() as u32);
 
-    // Fail if MPU is already configured
-    if core.MPU.ctrl.read() != 0 {
-        return Err(());
-    }
-
-    unsafe {
-        core.MPU.ctrl.write(5); // enable mpu with background default map
-        core.MPU.rbar.write(stack_bottom as u32 & !0xff); // set address
-        core.MPU.rlar.write(((stack_bottom as usize + 255) as u32) | 1);
-    }
     Ok(())
 }
 
diff --git a/embassy-rp/src/rom_data/rp235x.rs b/embassy-rp/src/rom_data/rp235x.rs
index b16fee8f7..c0a1ed6fb 100644
--- a/embassy-rp/src/rom_data/rp235x.rs
+++ b/embassy-rp/src/rom_data/rp235x.rs
@@ -750,3 +750,35 @@ pub fn is_secure_mode() -> bool {
 pub fn is_secure_mode() -> bool {
     false
 }
+
+// These and the reset_to_usb_boot function are found from https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2_common/pico_bootrom/bootrom.c#L35-L51
+// The following has just been translated to rust from the original c++
+const BOOTSEL_FLAG_GPIO_PIN_SPECIFIED: u32 = 0x20;
+const REBOOT2_FLAG_REBOOT_TYPE_BOOTSEL: u32 = 0x2;
+const REBOOT2_FLAG_NO_RETURN_ON_SUCCESS: u32 = 0x100;
+
+/// Resets the RP235x and uses the watchdog facility to re-start in BOOTSEL mode:
+///   * gpio_activity_pin_mask is provided to enable an 'activity light' via GPIO attached LED
+///     for the USB Mass Storage Device:
+///     * 0 No pins are used as per cold boot.
+///     * Otherwise a single bit set indicating which GPIO pin should be set to output and
+///       raised whenever there is mass storage activity from the host.
+///  * disable_interface_mask may be used to control the exposed USB interfaces:
+///    * 0 To enable both interfaces (as per cold boot).
+///    * 1 To disable the USB Mass Storage Interface.
+///    * 2 to Disable the USB PICOBOOT Interface.
+pub fn reset_to_usb_boot(mut usb_activity_gpio_pin_mask: u32, disable_interface_mask: u32) {
+    let mut flags = disable_interface_mask;
+
+    if usb_activity_gpio_pin_mask != 0 {
+        flags = flags | BOOTSEL_FLAG_GPIO_PIN_SPECIFIED;
+        usb_activity_gpio_pin_mask = usb_activity_gpio_pin_mask.trailing_zeros()
+    }
+
+    reboot(
+        REBOOT2_FLAG_REBOOT_TYPE_BOOTSEL | REBOOT2_FLAG_NO_RETURN_ON_SUCCESS,
+        10,
+        flags,
+        usb_activity_gpio_pin_mask,
+    );
+}