From 5b729322afbd03ca9ea16ebb6f59058d2baf8906 Mon Sep 17 00:00:00 2001
From: Daniel Schaefer <dhs@frame.work>
Date: Mon, 18 Nov 2024 14:16:27 +0800
Subject: [PATCH] Add rp2040 reset interface

This is the same one implemented in the rp-pico SDK.

See [definition](https://github.com/raspberrypi/pico-sdk/blob/2.0.0/src/rp2_common/pico_stdio_usb/stdio_usb_descriptors.c#L109)
and [usage](https://github.com/raspberrypi/pico-sdk/blob/2.0.0/src/rp2_common/pico_stdio_usb/reset_interface.c).

Since QMK does not use the USB descriptors from the SDK, we can't just
use `#define FOO PICO_STDIO_USB_ENABLE_RESET_VIA_VENDOR_INTERFACE` and
have to implement it ourselves.

Picotool writes a control transfer that arrives in `usb_request_hook_cb`
in `usbp->setup` as bytes `21 01 00 00 03 00 00 00`.

FWUPD also implements this same reset protocol
https://github.com/fwupd/fwupd/tree/main/plugins/rp-pico
Using this reset mechanism allows a standard reset into bootloader mode
from where UF2 update is easy.

The qmk commandline could also implement it to make debugging more
seamless.

Signed-off-by: Daniel Schaefer <dhs@frame.work>
---
 tmk_core/protocol/chibios/usb_main.c | 16 ++++++++++++++++
 tmk_core/protocol/usb_descriptor.c   | 13 +++++++++++++
 tmk_core/protocol/usb_descriptor.h   |  4 ++++
 3 files changed, 33 insertions(+)

diff --git a/tmk_core/protocol/chibios/usb_main.c b/tmk_core/protocol/chibios/usb_main.c
index 674f4c313e07..b3dab1f4a8c8 100644
--- a/tmk_core/protocol/chibios/usb_main.c
+++ b/tmk_core/protocol/chibios/usb_main.c
@@ -43,6 +43,7 @@
 #include "usb_device_state.h"
 #include "usb_descriptor.h"
 #include "usb_driver.h"
+#include "platforms/bootloader.h"
 
 #ifdef NKRO_ENABLE
 #    include "keycode_config.h"
@@ -651,6 +652,21 @@ static bool usb_request_hook_cb(USBDriver *usbp) {
      *  4,5: (LSB,MSB) wIndex
      *  6,7: (LSB,MSB) wLength (number of bytes to transfer if there is a data phase) */
 
+    if (((usbp->setup[0] & USB_RTYPE_TYPE_MASK) == USB_RTYPE_TYPE_CLASS) && ((usbp->setup[0] & USB_RTYPE_RECIPIENT_MASK) == USB_RTYPE_RECIPIENT_INTERFACE)) {
+        dprint("  TYPE_CLASS, RECIPIENT_INTERFACE\n");
+        if ((usbp->setup[0] & USB_RTYPE_DIR_MASK) == USB_RTYPE_DIR_HOST2DEV) {
+            if (usbp->setup[4] == RP2040_RESET_INTERFACE) {
+                switch (usbp->setup[1]) { /* bRequest */
+                    case 0x01: // RESET_REQUEST_BOOTSEL
+                    case 0x02: // RESET_REQUEST_FLASH
+                        dprint("  Reset interface\n");
+                        bootloader_jump();
+                    break;
+                }
+            }
+        }
+    }
+
     /* Handle HID class specific requests */
     if (((usbp->setup[0] & USB_RTYPE_TYPE_MASK) == USB_RTYPE_TYPE_CLASS) && ((usbp->setup[0] & USB_RTYPE_RECIPIENT_MASK) == USB_RTYPE_RECIPIENT_INTERFACE)) {
         switch (usbp->setup[0] & USB_RTYPE_DIR_MASK) {
diff --git a/tmk_core/protocol/usb_descriptor.c b/tmk_core/protocol/usb_descriptor.c
index 51f5f228fdb6..e6a1a71107ad 100644
--- a/tmk_core/protocol/usb_descriptor.c
+++ b/tmk_core/protocol/usb_descriptor.c
@@ -738,6 +738,19 @@ const USB_Descriptor_Configuration_t PROGMEM ConfigurationDescriptor = {
         .PollingIntervalMS      = USB_POLLING_INTERVAL_MS
     },
 #endif
+    .Rp2040_Reset_Interface = {
+        .Header = {
+            .Size               = sizeof(USB_Descriptor_Interface_t),
+            .Type               = DTYPE_Interface
+        },
+        .InterfaceNumber        = RP2040_RESET_INTERFACE,
+        .AlternateSetting       = 0x00,
+        .TotalEndpoints         = 2,
+        .Class                  = 0xFF,
+        .SubClass               = 0x00, // RESET_INTERFACE_SUBCLASS
+        .Protocol               = 0x01, // RESET_INTERFACE_PROTOCOL
+        .InterfaceStrIndex      = NO_DESCRIPTOR
+    },
 
 #ifdef CONSOLE_ENABLE
     /*
diff --git a/tmk_core/protocol/usb_descriptor.h b/tmk_core/protocol/usb_descriptor.h
index ddc2774e2d64..b6dd69d63357 100644
--- a/tmk_core/protocol/usb_descriptor.h
+++ b/tmk_core/protocol/usb_descriptor.h
@@ -92,6 +92,8 @@ typedef struct {
     USB_Descriptor_Endpoint_t  Shared_INEndpoint;
 #endif
 
+    USB_Descriptor_Interface_t Rp2040_Reset_Interface;
+
 #ifdef CONSOLE_ENABLE
     // Console HID Interface
     USB_Descriptor_Interface_t Console_Interface;
@@ -173,6 +175,8 @@ enum usb_interfaces {
     SHARED_INTERFACE,
 #endif
 
+    RP2040_RESET_INTERFACE,
+
 #ifdef CONSOLE_ENABLE
     CONSOLE_INTERFACE,
 #endif