trezor-firmware/embed/trezorhal/usb_webusb-impl.h

/*
 * This file is part of the TREZOR project, https://trezor.io/
 *
 * Copyright (c) SatoshiLabs
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#define USB_CLASS_WEBUSB                0xFF

/* usb_webusb_add adds and configures new USB WebUSB interface according to
 * configuration options passed in `info`. */
secbool usb_webusb_add(const usb_webusb_info_t *info) {

    usb_iface_t *iface = usb_get_iface(info->iface_num);

    if (iface == NULL) {
        return secfalse; // Invalid interface number
    }
    if (iface->type != USB_IFACE_TYPE_DISABLED) {
        return secfalse; // Interface is already enabled
    }

    usb_webusb_descriptor_block_t *d = usb_desc_alloc_iface(sizeof(usb_webusb_descriptor_block_t));

    if (d == NULL) {
        return secfalse; // Not enough space in the configuration descriptor
    }

    if ((info->ep_in & USB_EP_DIR_MASK) != USB_EP_DIR_IN) {
        return secfalse; // IN EP is invalid
    }
    if ((info->ep_out & USB_EP_DIR_MASK) != USB_EP_DIR_OUT) {
        return secfalse; // OUT EP is invalid
    }
    if (info->rx_buffer == NULL) {
        return secfalse;
    }

    // Interface descriptor
    d->iface.bLength            = sizeof(usb_interface_descriptor_t);
    d->iface.bDescriptorType    = USB_DESC_TYPE_INTERFACE;
    d->iface.bInterfaceNumber   = info->iface_num;
    d->iface.bAlternateSetting  = 0;
    d->iface.bNumEndpoints      = 2;
    d->iface.bInterfaceClass    = USB_CLASS_WEBUSB;
    d->iface.bInterfaceSubClass = info->subclass;
    d->iface.bInterfaceProtocol = info->protocol;
    d->iface.iInterface         = USBD_IDX_INTERFACE_STR;

    // IN endpoint (sending)
    d->ep_in.bLength          = sizeof(usb_endpoint_descriptor_t);
    d->ep_in.bDescriptorType  = USB_DESC_TYPE_ENDPOINT;
    d->ep_in.bEndpointAddress = info->ep_in;
    d->ep_in.bmAttributes     = USBD_EP_TYPE_INTR;
    d->ep_in.wMaxPacketSize   = info->max_packet_len;
    d->ep_in.bInterval        = info->polling_interval;

    // OUT endpoint (receiving)
    d->ep_out.bLength          = sizeof(usb_endpoint_descriptor_t);
    d->ep_out.bDescriptorType  = USB_DESC_TYPE_ENDPOINT;
    d->ep_out.bEndpointAddress = info->ep_out;
    d->ep_out.bmAttributes     = USBD_EP_TYPE_INTR;
    d->ep_out.wMaxPacketSize   = info->max_packet_len;
    d->ep_out.bInterval        = info->polling_interval;

    // Config descriptor
    usb_desc_add_iface(sizeof(usb_webusb_descriptor_block_t));

    // Interface state
    iface->type = USB_IFACE_TYPE_WEBUSB;
    iface->webusb.desc_block      = d;
    iface->webusb.rx_buffer       = info->rx_buffer;
    iface->webusb.ep_in           = info->ep_in;
    iface->webusb.ep_out          = info->ep_out;
    iface->webusb.max_packet_len  = info->max_packet_len;
    iface->webusb.alt_setting     = 0;
    iface->webusb.last_read_len   = 0;
    iface->webusb.ep_in_is_idle   = 1;

    return sectrue;
}

secbool usb_webusb_can_read(uint8_t iface_num) {
    usb_iface_t *iface = usb_get_iface(iface_num);
    if (iface == NULL) {
        return secfalse; // Invalid interface number
    }
    if (iface->type != USB_IFACE_TYPE_WEBUSB) {
        return secfalse; // Invalid interface type
    }
    if (iface->webusb.last_read_len == 0) {
        return secfalse; // Nothing in the receiving buffer
    }
    if (usb_dev_handle.dev_state != USBD_STATE_CONFIGURED) {
        return secfalse; // Device is not configured
    }
    return sectrue;
}

secbool usb_webusb_can_write(uint8_t iface_num) {
    usb_iface_t *iface = usb_get_iface(iface_num);
    if (iface == NULL) {
        return secfalse; // Invalid interface number
    }
    if (iface->type != USB_IFACE_TYPE_WEBUSB) {
        return secfalse; // Invalid interface type
    }
    if (iface->webusb.ep_in_is_idle == 0) {
        return secfalse; // Last transmission is not over yet
    }
    if (usb_dev_handle.dev_state != USBD_STATE_CONFIGURED) {
        return secfalse; // Device is not configured
    }
    return sectrue;
}

int usb_webusb_read(uint8_t iface_num, uint8_t *buf, uint32_t len) {
    usb_iface_t *iface = usb_get_iface(iface_num);
    if (iface == NULL) {
        return -1; // Invalid interface number
    }
    if (iface->type != USB_IFACE_TYPE_WEBUSB) {
        return -2; // Invalid interface type
    }
    usb_webusb_state_t *state = &iface->webusb;

    // Copy maximum possible amount of data and truncate the buffer length
    if (len < state->last_read_len) {
        return 0; // Not enough data in the read buffer
    }
    len = state->last_read_len;
    state->last_read_len = 0;
    memcpy(buf, state->rx_buffer, len);

    // Clear NAK to indicate we are ready to read more data
    usb_ep_clear_nak(&usb_dev_handle, state->ep_out);

    return len;
}

int usb_webusb_write(uint8_t iface_num, const uint8_t *buf, uint32_t len) {
    usb_iface_t *iface = usb_get_iface(iface_num);
    if (iface == NULL) {
        return -1; // Invalid interface number
    }
    if (iface->type != USB_IFACE_TYPE_WEBUSB) {
        return -2; // Invalid interface type
    }
    usb_webusb_state_t *state = &iface->webusb;

    state->ep_in_is_idle = 0;
    USBD_LL_Transmit(&usb_dev_handle, state->ep_in, UNCONST(buf), (uint16_t)len);

    return len;
}

int usb_webusb_read_select(uint32_t timeout) {
    const uint32_t start = HAL_GetTick();
    for (;;) {
        for (int i = 0; i < USBD_MAX_NUM_INTERFACES; i++) {
            if (sectrue == usb_webusb_can_read(i)) {
                return i;
            }
        }
        if (HAL_GetTick() - start >= timeout) {
            break;
        }
        __WFI(); // Enter sleep mode, waiting for interrupt
    }
    return -1; // Timeout
}

int usb_webusb_read_blocking(uint8_t iface_num, uint8_t *buf, uint32_t len, int timeout) {
    const uint32_t start = HAL_GetTick();
    while (sectrue != usb_webusb_can_read(iface_num)) {
        if (timeout >= 0 && HAL_GetTick() - start >= timeout) {
            return 0; // Timeout
        }
        __WFI(); // Enter sleep mode, waiting for interrupt
    }
    return usb_webusb_read(iface_num, buf, len);
}

int usb_webusb_write_blocking(uint8_t iface_num, const uint8_t *buf, uint32_t len, int timeout) {
    const uint32_t start = HAL_GetTick();
    while (sectrue != usb_webusb_can_write(iface_num)) {
        if (timeout >= 0 && HAL_GetTick() - start >= timeout) {
            return 0; // Timeout
        }
        __WFI(); // Enter sleep mode, waiting for interrupt
    }
    return usb_webusb_write(iface_num, buf, len);
}

static void usb_webusb_class_init(USBD_HandleTypeDef *dev, usb_webusb_state_t *state, uint8_t cfg_idx) {
    // Open endpoints
    USBD_LL_OpenEP(dev, state->ep_in, USBD_EP_TYPE_INTR, state->max_packet_len);
    USBD_LL_OpenEP(dev, state->ep_out, USBD_EP_TYPE_INTR, state->max_packet_len);

    // Reset the state
    state->alt_setting = 0;
    state->last_read_len = 0;
    state->ep_in_is_idle = 1;

    // Prepare the OUT EP to receive next packet
    USBD_LL_PrepareReceive(dev, state->ep_out, state->rx_buffer, state->max_packet_len);
}

static void usb_webusb_class_deinit(USBD_HandleTypeDef *dev, usb_webusb_state_t *state, uint8_t cfg_idx) {
    // Flush endpoints
    USBD_LL_FlushEP(dev, state->ep_in);
    USBD_LL_FlushEP(dev, state->ep_out);
    // Close endpoints
    USBD_LL_CloseEP(dev, state->ep_in);
    USBD_LL_CloseEP(dev, state->ep_out);
}

static int usb_webusb_class_setup(USBD_HandleTypeDef *dev, usb_webusb_state_t *state, USBD_SetupReqTypedef *req) {

    if ((req->bmRequest & USB_REQ_TYPE_MASK) != USB_REQ_TYPE_STANDARD) {
        return USBD_OK;
    }

    switch (req->bRequest) {

        case USB_REQ_SET_INTERFACE:
            state->alt_setting = req->wValue;
            USBD_CtlSendStatus(dev);
            return USBD_OK;

        case USB_REQ_GET_INTERFACE:
            USBD_CtlSendData(dev, &state->alt_setting, sizeof(state->alt_setting));
            return USBD_OK;

        default:
            USBD_CtlError(dev, req);
            return USBD_FAIL;
    }
}

static void usb_webusb_class_data_in(USBD_HandleTypeDef *dev, usb_webusb_state_t *state, uint8_t ep_num) {
    if ((ep_num | USB_EP_DIR_IN) == state->ep_in) {
        state->ep_in_is_idle = 1;
    }
}

static void usb_webusb_class_data_out(USBD_HandleTypeDef *dev, usb_webusb_state_t *state, uint8_t ep_num) {
    if (ep_num == state->ep_out) {
        state->last_read_len = USBD_LL_GetRxDataSize(dev, ep_num);

        // Prepare the OUT EP to receive next packet
        // User should provide state->rx_buffer that is big enough for state->max_packet_len bytes
        USBD_LL_PrepareReceive(dev, ep_num, state->rx_buffer, state->max_packet_len);

        if (state->last_read_len > 0) {
            // Block the OUT EP until we process received data
            usb_ep_set_nak(dev, ep_num);
        }
    }
}