edmfd_firmware/src/usb_descriptors.cc

#include "bsp/board_api.h"
#include "tusb.h"
#include "usb_descriptors.hh"

/* A combination of interfaces must have a unique product id, since PC will save device driver after the first plug.
 * Same VID/PID with different interface e.g MSC (first), then CDC (later) will possibly cause system error on PC.
 *
 * Auto ProductID layout's Bitmap:
 *   [MSB]         HID | MSC | CDC          [LSB]
 */
#define _PID_MAP(itf, n)  ( (CFG_TUD_##itf) << (n) )
#define USB_PID           (0x0000 | _PID_MAP(CDC, 0) | _PID_MAP(MSC, 1) | _PID_MAP(HID, 2) | \
                           _PID_MAP(MIDI, 3) | _PID_MAP(VENDOR, 4) )

#define USB_VID   0x4a33 // J3 in ascii
#define USB_BCD   0x0200

extern "C" {
    // TinyUSB callbacks
    uint8_t const * tud_descriptor_device_cb();
    uint8_t const * tud_hid_descriptor_report_cb(uint8_t);
    uint8_t const * tud_descriptor_configuration_cb(uint8_t);
    uint16_t const * tud_descriptor_string_cb(uint8_t, uint16_t);
}

//--------------------------------------------------------------------+
// Device Descriptors
//--------------------------------------------------------------------+
tusb_desc_device_t const desc_device = {
    .bLength            = sizeof(tusb_desc_device_t),
    .bDescriptorType    = TUSB_DESC_DEVICE,
    .bcdUSB             = USB_BCD,
    .bDeviceClass       = TUSB_CLASS_MISC,
    .bDeviceSubClass    = MISC_SUBCLASS_COMMON,
    .bDeviceProtocol    = MISC_PROTOCOL_IAD,
    .bMaxPacketSize0    = CFG_TUD_ENDPOINT0_SIZE,

    .idVendor           = USB_VID,
    .idProduct          = USB_PID,
    .bcdDevice          = 0x0100,

    .iManufacturer      = 0x01,
    .iProduct           = 0x02,
    .iSerialNumber      = 0x03,

    .bNumConfigurations = 0x01
};

// Invoked when received GET DEVICE DESCRIPTOR
// Application return pointer to descriptor
uint8_t const * tud_descriptor_device_cb(void) {
    return (uint8_t const *) &desc_device;
}

//--------------------------------------------------------------------+
// HID Report Descriptor
//--------------------------------------------------------------------+

uint8_t const desc_hid_report[] = {
    TUD_HID_REPORT_DESC_GAMEPAD ( HID_REPORT_ID(static_cast<uint8_t>(descriptor::gamepad)) )
};

// Invoked when received GET HID REPORT DESCRIPTOR
// Application return pointer to descriptor
// Descriptor contents must exist long enough for transfer to complete
uint8_t const * tud_hid_descriptor_report_cb(uint8_t) {
    return desc_hid_report;
}

//--------------------------------------------------------------------+
// String Descriptors
//--------------------------------------------------------------------+

enum class strings : uint8_t {
    language_id,
    manufacturer,
    product,
    serial,
    interface,
    _count
};

// array of pointer to string descriptors
char16_t const *string_desc_arr[size_t(strings::_count)] = {
    u"\u0409",          // 0: is supported language is English (0x0409)
    u"j3gaming",        // 1: Manufacturer
    u"EDMFD",           // 2: Product
    nullptr,            // 3: Serials will use unique ID if possible
    u"screen control",  // 4: screen interface
};

static constexpr size_t desc_len = 32;
static uint16_t desc_str[desc_len + 1];

// Invoked when received GET STRING DESCRIPTOR request
// Application return pointer to descriptor, whose contents must exist long enough for transfer to complete
uint16_t const *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
    (void) langid;
    size_t chr_count = 0;
    strings string_id = static_cast<strings>(index);

    switch (string_id) {
    case strings::serial:
        chr_count = board_usb_get_serial(desc_str + 1, desc_len);
        break;

    default:
        if (string_id >= strings::_count) return nullptr;
        uint16_t const *src = reinterpret_cast<uint16_t const*>(string_desc_arr[index]);
        uint16_t *dest = desc_str + 1;
        while (*src) {
            *dest++ = *src++;
            ++chr_count;
        }
        break;
    }

    // first byte is length (including header), second byte is string type
    desc_str[0] = (uint16_t) ((TUSB_DESC_STRING << 8) | (2 * chr_count + 2));
    return desc_str;
}

//--------------------------------------------------------------------+
// Configuration Descriptor
//--------------------------------------------------------------------+

static constexpr size_t config_total_len = TUD_CONFIG_DESC_LEN + TUD_HID_DESC_LEN + TUD_VENDOR_DESC_LEN;
enum class interface : uint8_t { HID, vendor, _count };
enum class endpoint : uint8_t { HID = 0x81, vendor_out = 0x02, vendor_in = 0x82 };

uint8_t const desc_configuration[config_total_len] = {
    // Config number, interface count, string index, total length, attribute, power in mA
    TUD_CONFIG_DESCRIPTOR(1, uint8_t(interface::_count), 0, config_total_len, TUSB_DESC_CONFIG_ATT_REMOTE_WAKEUP, 100),

    // Interface number, string index, protocol, report descriptor len, EP In address, size & polling interval
    TUD_HID_DESCRIPTOR(uint8_t(interface::HID), 0, HID_ITF_PROTOCOL_NONE, sizeof(desc_hid_report), uint8_t(endpoint::HID), CFG_TUD_HID_EP_BUFSIZE, 5),

    // Interface number, string index, EP Out & IN address, EP size
    TUD_VENDOR_DESCRIPTOR(uint8_t(interface::vendor), uint8_t(strings::interface), uint8_t(endpoint::vendor_out), uint8_t(endpoint::vendor_in), 64)

    // CDC: Interface number, string index, EP notification address and size, EP data address (out, in) and size.
    //TUD_CDC_DESCRIPTOR(uint8_t(interface::CDC), 4, uint8_t(endpoint::CDCnotify), 8, uint8_t(endpoint::CDCout), uint8_t(endpoint::CDCin), 64)
};


// Invoked when received GET CONFIGURATION DESCRIPTOR
// Application return pointer to descriptor
// Descriptor contents must exist long enough for transfer to complete
uint8_t const * tud_descriptor_configuration_cb(uint8_t index) {
    (void) index; // for multiple configurations

    // This example use the same configuration for both high and full speed mode
    return desc_configuration;
}