adafruit · tannewt · Oct 18, 2021 · Oct 3, 2021 · Oct 7, 2021 · Oct 7, 2021
diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
@@ -551,6 +551,10 @@ msgstr ""
 msgid "Bit depth must be multiple of 8."
 msgstr ""
 
+#: supervisor/shared/safe_mode.c
+msgid "Boot device must be first device (interface #0)."
+msgstr ""
+
 #: ports/mimxrt10xx/common-hal/busio/UART.c
 msgid "Both RX and TX required for flow control"
 msgstr ""

diff --git a/shared-bindings/usb_hid/Device.c b/shared-bindings/usb_hid/Device.c
@@ -50,7 +50,8 @@
 //|           Use a size of ``0`` for a report that is not an OUT report.
 //|         
8000
  "OUT" is with respect to the host.
 //|
-//|         ``report_ids``, ``in_report_lengths``, and ``out_report_lengths`` must all be the same length.
+//|         ``report_ids``, ``in_report_lengths``, and ``out_report_lengths`` must all have the
+//|         same number of elements.
 //|
 //|         Here is an example of a `Device` with a descriptor that specifies two report IDs, 3 and 4.
 //|         Report ID 3 sends an IN report of length 5, and receives an OUT report of length 6.
@@ -192,7 +193,7 @@ STATIC mp_obj_t usb_hid_device_send_report(size_t n_args, const mp_obj_t *pos_ar
 MP_DEFINE_CONST_FUN_OBJ_KW(usb_hid_device_send_report_obj, 1, usb_hid_device_send_report);
 
 //|     def get_last_received_report(self, report_id: Optional[int] = None) -> bytes:
-//|         """Get the last received HID OUT report for the given report ID.
+//|         """Get the last received HID OUT or feature report for the given report ID.
 //|         The report ID may be omitted if there is no report ID, or only one report ID.
 //|         Return `None` if nothing received.
 //|         """

diff --git a/shared-bindings/usb_hid/__init__.c b/shared-bindings/usb_hid/__init__.c
@@ -40,6 +40,11 @@
 //| """Tuple of all active HID device interfaces.
 //| The default set of devices is ``Device.KEYBOARD, Device.MOUSE, Device.CONSUMER_CONTROL``,
 //| On boards where `usb_hid` is disabled by default, `devices` is an empty tuple.
+//|
+//| If a boot device is enabled by `usb_hid.enable()`, *and* the host has requested a boot device,
+//| the `devices` tuple is **replaced** when ``code.py`` starts with a single-element tuple
+//| containing a `Device` that describes the boot device chosen (keyboard or mouse).
+//| The request for a boot device overrides any other HID devices.
 //| """
 //|
 
@@ -60,23 +65,61 @@ STATIC mp_obj_t usb_hid_disable(void) {
 }
 MP_DEFINE_CONST_FUN_OBJ_0(usb_hid_disable_obj, usb_hid_disable);
 
-//| def enable(devices: Optional[Sequence[Device]]) -> None:
+//| def enable(devices: Optional[Sequence[Device]], boot_device: int = 0) -> None:
 //|     """Specify which USB HID devices that will be available.
 //|     Can be called in ``boot.py``, before USB is connected.
 //|
 //|     :param Sequence devices: `Device` objects.
 //|       If `devices` is empty, HID is disabled. The order of the ``Devices``
 //|       may matter to the host. For instance, for MacOS, put the mouse device
 //|       before any Gamepad or Digitizer HID device or else it will not work.
+//|     :param int boot_device: If non-zero, inform the host that support for a
+//|       a boot HID device is available.
+//|       If ``boot_device=1``, a boot keyboard is available.
+//|       If ``boot_device=2``, a boot mouse is available. No other values are allowed.
+//|       See below.
 //|
 //|     If you enable too many devices at once, you will run out of USB endpoints.
 //|     The number of available endpoints varies by microcontroller.
 //|     CircuitPython will go into safe mode after running ``boot.py`` to inform you if
 //|     not enough endpoints are available.
+//|
+//|     **Boot Devices**
+//|
+//|     Boot devices implement a fixed, predefined report descriptor, defined in
+//|     https://www.usb.org/sites/default/files/hid1_12.pdf, Appendix B. A USB host
+//|     can request to use the boot device if the USB device says it is available.
+//|     Usually only a BIOS or other kind of limited-functionality
+//|     host needs boot keyboard support.
+//|
+//|     For example, to make a boot keyboard available, you can use this code::
+//|
+//|       usb_hid.enable((Device.KEYBOARD), boot_device=1)  # 1 for a keyboard
+//|
+//|     If the host requests the boot keyboard, the report descriptor provided by `Device.KEYBOARD`
+//|     will be ignored, and the predefined report descriptor will be used.
+//|     But if the host does not request the boot keyboard,
+//|     the descriptor provided by `Device.KEYBOARD` will be used.
+//|
+//|     The HID boot device must usually be the first or only device presented by CircuitPython.
+//|     The HID device will be USB interface number 0.
+//|     To make sure it is the first device, disable other USB devices, including CDC and MSC (CIRCUITPY).
+//|     If you specify a non-zero ``boot_device``, and it is not the first device, CircuitPython
+//|     will enter safe mode to report this error.
 //|     """
 //|     ...
 //|
-STATIC mp_obj_t usb_hid_enable(mp_obj_t devices) {
+STATIC mp_obj_t usb_hid_enable(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_devices, ARG_boot_device };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_devices, MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_boot_device, MP_ARG_INT, {.u_int = 0} },
+    };
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    mp_obj_t devices = args[ARG_devices].u_obj;
     const mp_int_t len = mp_obj_get_int(mp_obj_len(devices));
     for (mp_int_t i = 0; i < len; i++) {
         mp_obj_t item = mp_obj_subscr(devices, MP_OBJ_NEW_SMALL_INT(i), MP_OBJ_SENTINEL);
@@ -85,21 +128,44 @@ STATIC mp_obj_t usb_hid_enable(mp_obj_t devices) {
         }
     }
 
-    if (!common_hal_usb_hid_enable(devices)) {
+    uint8_t boot_device =
+        (uint8_t)mp_arg_validate_int_range(args[ARG_boot_device].u_int, 0, 2, MP_QSTR_boot_device);
+
+    if (!common_hal_usb_hid_enable(devices, boot_device)) {
         mp_raise_RuntimeError(translate("Cannot change USB devices now"));
     }
 
     return mp_const_none;
 }
-MP_DEFINE_CONST_FUN_OBJ_1(usb_hid_enable_obj, usb_hid_enable);
+MP_DEFINE_CONST_FUN_OBJ_KW(usb_hid_enable_obj, 1, usb_hid_enable);
+
+//| def get_boot_device() -> int:
+//|     """
+//|     :return: the boot device requested by the host, if any.
+//|       Returns 0 if the host did not request a boot device, or if `usb_hid.enable()`
+//|       was called with ``boot_device=0``, the default, which disables boot device support.
+//|       If the host did request a boot device,
+//|       returns the value of ``boot_device`` set in `usb_hid.enable()`:
+//|       ``1`` for a boot keyboard, or ``2`` for boot mouse.
+//|       However, the standard devices provided by CircuitPython, `Device.KEYBOARD` and `Device.MOUSE`,
+//|       describe reports that match the boot device reports, so you don't need to check this
+//|       if you are using those devices.
+//|     :rtype int:
+//|     """
+//|
+STATIC mp_obj_t usb_hid_get_boot_device(void) {
+    return MP_OBJ_NEW_SMALL_INT(common_hal_usb_hid_get_boot_device());
+}
+MP_DEFINE_CONST_FUN_OBJ_0(usb_hid_get_boot_device_obj, usb_hid_get_boot_device);
 
 // usb_hid.devices is set once the usb devices are determined, after boot.py runs.
 STATIC mp_map_elem_t usb_hid_module_globals_table[] = {
-    { MP_ROM_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_usb_hid) },
-    { MP_ROM_QSTR(MP_QSTR_Device),   MP_OBJ_FROM_PTR(&usb_hid_device_type) },
-    { MP_ROM_QSTR(MP_QSTR_devices),  mp_const_none },
-    { MP_ROM_QSTR(MP_QSTR_disable),  MP_OBJ_FROM_PTR(&usb_hid_disable_obj) },
-    { MP_ROM_QSTR(MP_QSTR_enable),   MP_OBJ_FROM_PTR(&usb_hid_enable_obj) },
+    { MP_ROM_QSTR(MP_QSTR___name__),        MP_OBJ_NEW_QSTR(MP_QSTR_usb_hid) },
+    { MP_ROM_QSTR(MP_QSTR_Device),          MP_OBJ_FROM_PTR(&usb_hid_device_type) },
+    { MP_ROM_QSTR(MP_QSTR_devices),         mp_const_none },
+    { MP_ROM_QSTR(MP_QSTR_disable),         MP_OBJ_FROM_PTR(&usb_hid_disable_obj) },
+    { MP_ROM_QSTR(MP_QSTR_enable),          MP_OBJ_FROM_PTR(&usb_hid_enable_obj) },
+    { MP_ROM_QSTR(MP_QSTR_get_boot_device), MP_OBJ_FROM_PTR(&usb_hid_get_boot_device_obj) },
 };
 
 STATIC MP_DEFINE_MUTABLE_DICT(usb_hid_module_globals, usb_hid_module_globals_table);

diff --git a/shared-bindings/usb_hid/__init__.h b/shared-bindings/usb_hid/__init__.h
@@ -36,6 +36,7 @@ extern mp_obj_tuple_t common_hal_usb_hid_devices;
 void usb_hid_set_devices(mp_obj_t devices);
 
 bool common_hal_usb_hid_disable(void);
-bool common_hal_usb_hid_enable(const mp_obj_t devices_seq);
+bool common_hal_usb_hid_enable(const mp_obj_t devices_seq, uint8_t boot_device);
+uint8_t common_hal_usb_hid_get_boot_device(void);
 
 #endif // SHARED_BINDINGS_USB_HID_H
diff --git a/shared-module/usb_hid/Device.c b/shared-module/usb_hid/Device.c
@@ -244,7 +244,7 @@ void common_hal_usb_hid_device_send_report(usb_hid_device_obj_t *self, uint8_t *
 }
 
 mp_obj_t common_hal_usb_hid_device_get_last_received_report(usb_hid_device_obj_t *self, uint8_t report_id) {
-    // report_id has already been validated for this deveice.
+    // report_id has already been validated for this device.
     size_t id_idx = get_report_id_idx(self, report_id);
     return mp_obj_new_bytes(self->out_report_buffers[id_idx], self->out_report_lengths[id_idx]);
 }
@@ -266,11 +266,11 @@ void usb_hid_device_create_report_buffers(usb_hid_device_obj_t *self) {
 }
 
 
-// 
9E81
Callbacks invoked when we received Get_Report request through control endpoint
+// Callback invoked when we receive Get_Report request through control endpoint
 uint16_t tud_hid_get_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t report_type, uint8_t *buffer, uint16_t reqlen) {
     (void)itf;
-    // only support Input Report
-    if (report_type != HID_REPORT_TYPE_INPUT) {
+    // Support Input Report and Feature Report
+    if (report_type != HID_REPORT_TYPE_INPUT && report_type != HID_REPORT_TYPE_FEATURE) {
         return 0;
     }
 
@@ -289,14 +289,14 @@ uint16_t tud_hid_get_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t
     return 0;
 }
 
-// Callbacks invoked when we received Set_Report request through control endpoint
+// Callback invoked when we receive Set_Report request through control endpoint
 void tud_hid_set_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t report_type, uint8_t const *buffer, uint16_t bufsize) {
     (void)itf;
     if (report_type == HID_REPORT_TYPE_INVALID) {
         report_id = buffer[0];
         buffer++;
         bufsize--;
-    } else if (report_type != HID_REPORT_TYPE_OUTPUT) {
+    } else if (report_type != HID_REPORT_TYPE_OUTPUT && report_type != HID_REPORT_TYPE_FEATURE) {
         return;
     }
 

diff --git a/shared-module/usb_hid/__init__.c b/shared-module/usb_hid/__init__.c
@@ -31,7 +31,7 @@
 #include "py/gc.h"
 #include "py/runtime.h"
 #include "shared-bindings/usb_hid/__init__.h"
-#include "shared-module/usb_hid/Device.h"
+#include "shared-bindings/usb_hid/Device.h"
 #include "supervisor/memory.h"
 #include "supervisor/usb.h"
 
@@ -44,7 +44,9 @@ static const uint8_t usb_hid_descriptor_template[] = {
     0x02,        //  4 bNumEndpoints 2
     0x03,        //  5 bInterfaceClass: HID
     0x00,        //  6 bInterfaceSubClass: NOBOOT
+#define HID_DESCRIPTOR_SUBCLASS_INDEX (6)
     0x00,        //  7 bInterfaceProtocol: NONE
+#define HID_DESCRIPTOR_INTERFACE_PROTOCOL_INDEX (7)
     0xFF,        //  8 iInterface (String Index)  [SET AT RUNTIME]
 #define HID_DESCRIPTOR_INTERFACE_STRING_INDEX (8)
 
@@ -81,6 +83,14 @@ static usb_hid_device_obj_t hid_devices[MAX_HID_DEVICES];
 // If 0, USB HID is disabled.
 static mp_int_t num_hid_devices;
 
+// Which boot device is available? 0: no boot devices, 1: boot keyboard, 2: boot mouse.
+// This value is set by usb_hid.enable(), and used to build the HID interface descriptor.
+// The value is remembered here from boot.py to code.py.
+static uint8_t hid_boot_device;
+
+// Whether a boot device was requested by a SET_PROTOCOL request from the host.
+static bool hid_boot_device_requested;
+
 // This tuple is store in usb_hid.devices.
 static mp_obj_tuple_t *hid_devices_tuple;
 
@@ -96,13 +106,56 @@ static mp_obj_tuple_t default_hid_devices_tuple = {
     },
 };
 
+// These describe the standard descriptors used for boot keyboard and mouse, which don't use report IDs.
+// When the host requests a boot device, replace whatever HID devices were enabled with a tuple
+// containing just one of these, since the host is uninterested in other devices.
+// The driver code will then use the proper report length and send_report() will not send a report ID.
+static const usb_hid_device_obj_t boot_keyboard_obj = {
+    .base = {
+        .type = &usb_hid_device_type,
+    },
+    .report_descriptor = NULL,
+    .report_descriptor_length = 0,
+    .usage_page = 0x01,
+    .usage = 0x06,
+    .num_report_ids = 1,
+    .report_ids = { 0, },
+    .in_report_lengths = { 8, },
+    .out_report_lengths = { 1, },
+};
+
+static const usb_hid_device_obj_t boot_mouse_obj = {
+    .base = {
+        .type = &usb_hid_device_type,
+    },
+    .report_descriptor = NULL,
+    .report_descriptor_length = 0,
+    .usage_page = 0x01,
+    .usage = 0x02,
+    .num_report_ids = 1,
+    .report_ids = { 0, },
+    .in_report_lengths = { 4, },
+    .out_report_lengths = { 0, },
+};
+
 bool usb_hid_enabled(void) {
     return num_hid_devices > 0;
 }
 
+uint8_t usb_hid_boot_device(void) {
+    return hid_boot_device;
+}
+
+// Returns 1 or 2 if host requested a boot device and boot protocol was enabled in the interface descriptor.
+uint8_t common_hal_usb_hid_get_boot_device(void) {
+    return hid_boot_device_requested ? hid_boot_device : 0;
+}
+
 void usb_hid_set_defaults(void) {
+    hid_boot_device = 0;
+    hid_boot_device_requested = false;
     common_hal_usb_hid_enable(
-        CIRCUITPY_USB_HID_ENABLED_DEFAULT ? &default_hid_devices_tuple : mp_const_empty_tuple);
+        CIRCUITPY_USB_HID_ENABLED_DEFAULT ? &default_hid_devices_tuple : mp_const_empty_tuple, 0);
 }
 
 // This is the interface descriptor, not the report descriptor.
@@ -113,12 +166,17 @@ size_t usb_hid_descriptor_length(void) {
 static const char usb_hid_interface_name[] = USB_INTERFACE_NAME " HID";
 
 // This is the interface descriptor, not the report descriptor.
-size_t usb_hid_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *descriptor_counts, uint8_t *current_interface_string, uint16_t report_descriptor_length) {
+size_t usb_hid_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *descriptor_counts, uint8_t *current_interface_string, uint16_t report_descriptor_length, uint8_t boot_device) {
     memcpy(descriptor_buf, usb_hid_descriptor_template, sizeof(usb_hid_descriptor_template));
 
     descriptor_buf[HID_DESCRIPTOR_INTERFACE_INDEX] = descriptor_counts->current_interface;
     descriptor_counts->current_interface++;
 
+    if (boot_device > 0) {
+        descriptor_buf[HID_DESCRIPTOR_SUBCLASS_INDEX] = 1; // BOOT protocol (device) available.
+        descriptor_buf[HID_DESCRIPTOR_INTERFACE_PROTOCOL_INDEX] = boot_device; // 1: keyboard, 2: mouse
+    }
+
     usb_add_interface_string(*current_interface_string, usb_hid_interface_name);
     descriptor_buf[HID_DESCRIPTOR_INTERFACE_STRING_INDEX] = *current_interface_string;
     (*current_interface_string)++;
@@ -151,10 +209,10 @@ static void usb_hid_set_devices_from_hid_devices(void) {
 }
 
 bool common_hal_usb_hid_disable(void) {
-    return common_hal_usb_hid_enable(mp_const_empty_tuple);
+    return common_hal_usb_hid_enable(mp_const_empty_tuple, 0);
 }
 
-bool common_hal_usb_hid_enable(const mp_obj_t devices) {
+bool common_hal_usb_hid_enable(const mp_obj_t devices, uint8_t boot_device) {
     // We can't change the devices once we're connected.
     if (tud_connected()) {
         return false;
@@ -167,6 +225,8 @@ bool common_hal_usb_hid_enable(const mp_obj_t devices) {
 
     num_hid_devices = num_devices;
 
+    hid_boot_device = boot_device;
+
     // Remember the devices in static storage so they live across VMs.
     for (mp_int_t i = 0; i < num_hid_devices; i++) {
         // devices has already been validated to contain only usb_hid_device_obj_t objects.
@@ -182,6 +242,17 @@ bool common_hal_usb_hid_enable(const mp_obj_t devices) {
 
 // Called when HID devices are ready to be used, when code.py or the REPL starts running.
 void usb_hid_setup_devices(void) {
+
+    // If the host requested a boot device, replace the current list of devices
+    // with a single-element tuple containing the proper boot device.
+    if (hid_boot_device_requested) {
+        memcpy(&hid_devices[0],
+            // Will be 1 (keyboard) or 2 (mouse).
+            hid_boot_device == 1 ? &boot_keyboard_obj : &boot_mouse_obj,
+            sizeof(usb_hid_device_obj_t));
+        num_hid_devices = 1;
+    }
+
     usb_hid_set_devices_from_hid_devices();
 
     // Create report buffers on the heap.
@@ -272,9 +343,15 @@ bool usb_hid_get_device_with_report_id(uint8_t report_id, usb_hid_device_obj_t *
     return false;
 }
 
-// Invoked when GET HID REPORT DESCRIPTOR is received.
-// Application return pointer to descriptor
+// Callback invoked when we receive a GET HID REPORT DESCRIPTOR
+// Application returns pointer to descriptor
 // Descriptor contents must exist long enough for transfer to complete
 uint8_t const *tud_hid_descriptor_report_cb(uint8_t itf) {
     return (uint8_t *)hid_report_descriptor_allocation->ptr;
 }
+
+// Callback invoked when we receive a SET_PROTOCOL request.
+// Protocol is either HID_PROTOCOL_BOOT (0) or HID_PROTOCOL_REPORT (1)
+void tud_hid_set_protocol_cb(uint8_t instance, uint8_t protocol) {
+    hid_boot_device_requested = (protocol == HID_PROTOCOL_BOOT);
+}
diff --git a/shared-module/usb_hid/__init__.h b/shared-module/usb_hid/__init__.h
@@ -33,9 +33,10 @@
 extern usb_hid_device_obj_t usb_hid_devices[];
 
 bool usb_hid_enabled(void);
+uint8_t usb_hid_boot_device(void);
 void usb_hid_set_defaults(void);
 
-size_t usb_hid_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *descriptor_counts, uint8_t *current_interface_string, uint16_t report_descriptor_length);
+size_t usb_hid_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *descriptor_counts, uint8_t *current_interface_string, uint16_t report_descriptor_length, uint8_t boot_device);
 size_t usb_hid_descriptor_length(void);
 size_t usb_hid_report_descriptor_length(void);
 

diff --git a/supervisor/shared/safe_mode.c b/supervisor/shared/safe_mode.c
@@ -169,6 +169,9 @@ void print_safe_mode_message(safe_mode_t reason) {
         case USB_TOO_MANY_INTERFACE_NAMES:
             message = translate("USB devices specify too many interface names.");
             break;
+        case USB_BOOT_DEVICE_NOT_INTERFACE_ZERO:
+            message = translate("Boot device must be first device (interface #0).");
+            break;
         case WATCHDOG_RESET:
             message = translate("Watchdog timer expired.");
             break;