RP2350A-A2 USB BOOT activity LED workaround

src/rp2350/pico_platform/include/pico/platform.h

@@ -189,7 +189,7 @@ __force_inline static bool pico_processor_state_is_nonsecure(void) {
 
 /*! \brief Returns the RP2350 chip revision number
  *  \ingroup pico_platform
- * @return the RP2350 chip revision number (1 for B0/B1, 2 for B2)
+ * @return the RP2350 chip revision number (2 for A2, 3 for A3/A4)
  */
 uint8_t rp2350_chip_version(void);
 
@@ -201,11 +201,11 @@ static inline uint8_t rp2040_chip_version(void) {
     return 2;
 }
 
-/*! \brief Returns the RP2040 rom version number
+/*! \brief Returns the RP2350 rom version number
  *  \ingroup pico_platform
- * @return the RP2040 rom version number (1 for RP2040-B0, 2 for RP2040-B1, 3 for RP2040-B2)
+ * @return the RP2350 rom version number (2 for RP2350-A2, 3 for RP2350-A3, 4 for RP2350-A4)
  */
-static inline uint8_t rp2040_rom_version(void) {
+static inline uint8_t rp2350_rom_version(void) {
     GCC_Pragma("GCC diagnostic push")
     GCC_Pragma("GCC diagnostic ignored \"-Warray-bounds\"")
     return *(uint8_t*)0x13;

src/rp2_common/pico_bootrom/bootrom.c

@@ -31,6 +31,19 @@ bool rom_funcs_lookup(uint32_t *table, unsigned int count) {
     return ok;
 }
 
+// The activity LED on RP2350 A2 QFN60 chips doesn't work in Arm mode, so boot into RISC-V if the user
+// really, really wants the activity LED
+#if PICO_RP2350_A2_SUPPORTED && PICO_RP2350A && !PICO_RISCV && PICO_BOOTROM_WORKAROUND_RP2350_A2_ACTIVITY_LED_BUG
+#define rom_reboot_workaround(flags, delay_ms, p0, p1) ({ \
+    if (((p0) & BOOTSEL_FLAG_GPIO_PIN_SPECIFIED) && rp2350_rom_version() == 2) \
+        rom_reboot((flags) | REBOOT2_FLAG_REBOOT_TO_RISCV, delay_ms, p0, p1); \
+    else \
+        rom_reboot(flags, delay_ms, p0, p1); \
+})
+#else
+#define rom_reboot_workaround(flags, delay_ms, p0, p1) rom_reboot(flags, delay_ms, p0, p1)
+#endif
+
 
 void __attribute__((noreturn)) rom_reset_usb_boot(uint32_t usb_activity_gpio_pin_mask, uint32_t disable_interface_mask) {
 #ifdef ROM_FUNC_RESET_USB_BOOT
@@ -43,7 +56,7 @@ void __attribute__((noreturn)) rom_reset_usb_boot(uint32_t usb_activity_gpio_pin
         // the parameter is actually the gpio number, but we only care if BOOTSEL_FLAG_GPIO_PIN_SPECIFIED
         usb_activity_gpio_pin_mask = (uint32_t)__builtin_ctz(usb_activity_gpio_pin_mask);
     }
-    rom_reboot(REBOOT2_FLAG_REBOOT_TYPE_BOOTSEL | REBOOT2_FLAG_NO_RETURN_ON_SUCCESS, 10, flags, usb_activity_gpio_pin_mask);
+    rom_reboot_workaround(REBOOT2_FLAG_REBOOT_TYPE_BOOTSEL | REBOOT2_FLAG_NO_RETURN_ON_SUCCESS, 10, flags, usb_activity_gpio_pin_mask);
     __builtin_unreachable();
 #else
     panic_unsupported();
@@ -63,7 +76,7 @@ void __attribute__((noreturn)) rom_reset_usb_boot_extra(int usb_activity_gpio_pi
             flags |= BOOTSEL_FLAG_GPIO_PIN_ACTIVE_LOW;
         }
     }
-    rom_reboot(REBOOT2_FLAG_REBOOT_TYPE_BOOTSEL | REBOOT2_FLAG_NO_RETURN_ON_SUCCESS, 10, flags, (uint)usb_activity_gpio_pin);
+    rom_reboot_workaround(REBOOT2_FLAG_REBOOT_TYPE_BOOTSEL | REBOOT2_FLAG_NO_RETURN_ON_SUCCESS, 10, flags, (uint)usb_activity_gpio_pin);
     __builtin_unreachable();
 #else
     panic_unsupported();

src/rp2_common/pico_bootrom/include/pico/bootrom.h

@@ -241,6 +241,13 @@ static __force_inline void *rom_data_lookup_inline(uint32_t code) {
 }
 #pragma GCC diagnostic pop
 
+#if PICO_RP2350
+// PICO_CONFIG: PICO_BOOTROM_WORKAROUND_RP2350_A2_ACTIVITY_LED_BUG, Workaround RP2350A-A2 (QFN60) bug not displaying USB boot activity LED under Arm by making rom_reset_usb_boot functions reboot to RISC-V when the activity LED is specified, type=bool, default=1, group=pico_bootrom
+#ifndef PICO_BOOTROM_WORKAROUND_RP2350_A2_ACTIVITY_LED_BUG
+#define PICO_BOOTROM_WORKAROUND_RP2350_A2_ACTIVITY_LED_BUG 1
+#endif
+#endif
+
 /*!
  * \brief Reboot the device into BOOTSEL mode
  * \ingroup pico_bootrom
@@ -250,7 +257,13 @@ static __force_inline void *rom_data_lookup_inline(uint32_t code) {
  * Facilities are provided to enable an "activity light" via GPIO attached LED for the USB Mass Storage Device,
  * and to limit the USB interfaces exposed.
  *
- * \param usb_activity_gpio_pin_mask 0 No pins are used as per a cold boot. Otherwise a single bit set indicating which
+ * \if rp2350_specific
+ * \note On RP2350A-A2 chips, errata RP2350-E3 prevents the activity LED working under Arm.
+ *       PICO_BOOTROM_WORKAROUND_RP2350_A2_ACTIVITY_LED_BUG=1 is defined by default to have this method reboot to
+ *       RISC-V USB boot to display the activity LED correctly.
+ * \endif
+ *
+ * \param usb_activity_gpio_pin_mask 0 No pins are used as per a 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.
  * \param disable_interface_mask value to control exposed interfaces
@@ -272,13 +285,19 @@ static inline void __attribute__((noreturn)) reset_usb_boot(uint32_t usb_activit
  * Facilities are provided to enable an "activity light" via GPIO attached LED for the USB Mass Storage Device,
  * and to limit the USB interfaces exposed.
  *
+ * \if rp2350_specific
+ * \note On RP2350A-A2 chips, errata RP2350-E3 prevents the activity LED working under Arm.
+ *       PICO_BOOTROM_WORKAROUND_RP2350_A2_ACTIVITY_LED_BUG=1 is defined by default to have this method reboot to
+ *       RISC-V USB boot to display the activity LED correctly.
+ * \endif
+ *
  * \param usb_activity_gpio_pin  GPIO pin to be used as an activitiy pin, or -1 for none
- *                               from the host.
  * \param disable_interface_mask value to control exposed interfaces
  *  - 0 To enable both interfaces (as per a cold boot)
  *  - 1 To disable the USB Mass Storage Interface
  *  - 2 To disable the USB PICOBOOT Interface
- * \param usb_activity_gpio_pin_active_low Activity GPIO is active low (ignored on RP2040)
+ * \param usb_activity_gpio_pin_active_low Activity GPIO is active low (ignored on RP2040). A bug in the bootrom of RP2350
+ *                                         A4 chips means this parameter has no effect on that version of the RP2350.
  */
 void __attribute__((noreturn)) rom_reset_usb_boot_extra(int usb_activity_gpio_pin, uint32_t disable_interface_mask, bool usb_activity_gpio_pin_active_low);