circuitpython/ports/stm32/usbd_cdc_interface.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * Taken from ST Cube library and heavily modified.  See below for original
 * copyright header.
 */

/**
  ******************************************************************************
  * @file    USB_Device/CDC_Standalone/Src/usbd_cdc_interface.c
  * @author  MCD Application Team
  * @version V1.0.1
  * @date    26-February-2014
  * @brief   Source file for USBD CDC interface
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT(c) 2014 STMicroelectronics</center></h2>
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
  */

/* Includes ------------------------------------------------------------------*/

#include <stdbool.h>
#include <stdint.h>

#include "usbd_cdc_msc_hid.h"
#include "usbd_cdc_interface.h"
#include "pendsv.h"

#include "py/obj.h"
#include "lib/utils/interrupt_char.h"
#include "irq.h"

// CDC control commands
#define CDC_SEND_ENCAPSULATED_COMMAND               0x00
#define CDC_GET_ENCAPSULATED_RESPONSE               0x01
#define CDC_SET_COMM_FEATURE                        0x02
#define CDC_GET_COMM_FEATURE                        0x03
#define CDC_CLEAR_COMM_FEATURE                      0x04
#define CDC_SET_LINE_CODING                         0x20
#define CDC_GET_LINE_CODING                         0x21
#define CDC_SET_CONTROL_LINE_STATE                  0x22
#define CDC_SEND_BREAK                              0x23

uint8_t *usbd_cdc_init(usbd_cdc_itf_t *cdc, usbd_cdc_msc_hid_state_t *usbd) {
    // Link the parent state
    cdc->usbd = usbd;

    // Reset all the CDC state
    // Note: we don't reset tx_buf_ptr_in in order to allow the output buffer to
    // be filled (by usbd_cdc_tx_always) before the USB device is connected.
    cdc->rx_buf_put = 0;
    cdc->rx_buf_get = 0;
    cdc->tx_buf_ptr_out = 0;
    cdc->tx_buf_ptr_out_shadow = 0;
    cdc->tx_buf_ptr_wait_count = 0;
    cdc->tx_need_empty_packet = 0;
    cdc->dev_is_connected = 0;

    // Return the buffer to place the first USB OUT packet
    return cdc->rx_packet_buf;
}

// Manage the CDC class requests
// cmd: command code
// pbuf: buffer containing command data (request parameters)
// length: number of data to be sent (in bytes)
// Returns USBD_OK if all operations are OK else USBD_FAIL
int8_t usbd_cdc_control(usbd_cdc_itf_t *cdc, uint8_t cmd, uint8_t* pbuf, uint16_t length) {
    switch (cmd) {
        case CDC_SEND_ENCAPSULATED_COMMAND:
            /* Add your code here */
            break;

        case CDC_GET_ENCAPSULATED_RESPONSE:
            /* Add your code here */
            break;

        case CDC_SET_COMM_FEATURE:
            /* Add your code here */
            break;

        case CDC_GET_COMM_FEATURE:
            /* Add your code here */
            break;

        case CDC_CLEAR_COMM_FEATURE:
            /* Add your code here */
            break;

        case CDC_SET_LINE_CODING:
            #if 0
            LineCoding.bitrate    = (uint32_t)(pbuf[0] | (pbuf[1] << 8) |\
                                    (pbuf[2] << 16) | (pbuf[3] << 24));
            LineCoding.format     = pbuf[4];
            LineCoding.paritytype = pbuf[5];
            LineCoding.datatype   = pbuf[6];
            /* Set the new configuration */
            #endif
            break;

        case CDC_GET_LINE_CODING:
            /* Add your code here */
            pbuf[0] = (uint8_t)(115200);
            pbuf[1] = (uint8_t)(115200 >> 8);
            pbuf[2] = (uint8_t)(115200 >> 16);
            pbuf[3] = (uint8_t)(115200 >> 24);
            pbuf[4] = 0; // stop bits (1)
            pbuf[5] = 0; // parity (none)
            pbuf[6] = 8; // number of bits (8)
            break;

        case CDC_SET_CONTROL_LINE_STATE:
            cdc->dev_is_connected = length & 1; // wValue is passed in Len (bit of a hack)
            break;

        case CDC_SEND_BREAK:
            /* Add your code here */
            break;

        default:
            break;
    }

    return USBD_OK;
}

// This function is called to process outgoing data.  We hook directly into the
// SOF (start of frame) callback so that it is called exactly at the time it is
// needed (reducing latency), and often enough (increasing bandwidth).
void HAL_PCD_SOFCallback(PCD_HandleTypeDef *hpcd) {
    usbd_cdc_msc_hid_state_t *usbd = ((USBD_HandleTypeDef*)hpcd->pData)->pClassData;
    usbd_cdc_itf_t *cdc = usbd->cdc;

    if (cdc == NULL || !cdc->dev_is_connected) {
        // CDC device is not connected to a host, so we are unable to send any data
        return;
    }

    if (cdc->tx_buf_ptr_out == cdc->tx_buf_ptr_in && !cdc->tx_need_empty_packet) {
        // No outstanding data to send
        return;
    }

    if (cdc->tx_buf_ptr_out != cdc->tx_buf_ptr_out_shadow) {
        // We have sent data and are waiting for the low-level USB driver to
        // finish sending it over the USB in-endpoint.
        // SOF occurs every 1ms, so we have a 500 * 1ms = 500ms timeout
        // We have a relatively large timeout because the USB host may be busy
        // doing other things and we must give it a chance to read our data.
        if (cdc->tx_buf_ptr_wait_count < 500) {
            USB_OTG_GlobalTypeDef *USBx = hpcd->Instance;
            if (USBx_INEP(CDC_IN_EP & 0x7f)->DIEPTSIZ & USB_OTG_DIEPTSIZ_XFRSIZ) {
                // USB in-endpoint is still reading the data
                cdc->tx_buf_ptr_wait_count++;
                return;
            }
        }
        cdc->tx_buf_ptr_out = cdc->tx_buf_ptr_out_shadow;
    }

    if (cdc->tx_buf_ptr_out_shadow != cdc->tx_buf_ptr_in || cdc->tx_need_empty_packet) {
        uint32_t buffptr;
        uint32_t buffsize;

        if (cdc->tx_buf_ptr_out_shadow > cdc->tx_buf_ptr_in) { // rollback
            buffsize = USBD_CDC_TX_DATA_SIZE - cdc->tx_buf_ptr_out_shadow;
        } else {
            buffsize = cdc->tx_buf_ptr_in - cdc->tx_buf_ptr_out_shadow;
        }

        buffptr = cdc->tx_buf_ptr_out_shadow;

        if (USBD_CDC_TransmitPacket(cdc->usbd, buffsize, &cdc->tx_buf[buffptr]) == USBD_OK) {
            cdc->tx_buf_ptr_out_shadow += buffsize;
            if (cdc->tx_buf_ptr_out_shadow == USBD_CDC_TX_DATA_SIZE) {
                cdc->tx_buf_ptr_out_shadow = 0;
            }
            cdc->tx_buf_ptr_wait_count = 0;

            // According to the USB specification, a packet size of 64 bytes (CDC_DATA_FS_MAX_PACKET_SIZE)
            // gets held at the USB host until the next packet is sent.  This is because a
            // packet of maximum size is considered to be part of a longer chunk of data, and
            // the host waits for all data to arrive (ie, waits for a packet < max packet size).
            // To flush a packet of exactly max packet size, we need to send a zero-size packet.
            // See eg http://www.cypress.com/?id=4&rID=92719
            cdc->tx_need_empty_packet = (buffsize > 0 && buffsize % usbd_cdc_max_packet(usbd->pdev) == 0 && cdc->tx_buf_ptr_out_shadow == cdc->tx_buf_ptr_in);
        }
    }
}

// Data received over USB OUT endpoint is processed here.
// len: number of bytes received into the buffer we passed to USBD_CDC_ReceivePacket
// Returns USBD_OK if all operations are OK else USBD_FAIL
int8_t usbd_cdc_receive(usbd_cdc_itf_t *cdc, size_t len) {
    // copy the incoming data into the circular buffer
    for (const uint8_t *src = cdc->rx_packet_buf, *top = cdc->rx_packet_buf + len; src < top; ++src) {
        if (mp_interrupt_char != -1 && *src == mp_interrupt_char) {
            pendsv_kbd_intr();
        } else {
            uint16_t next_put = (cdc->rx_buf_put + 1) & (USBD_CDC_RX_DATA_SIZE - 1);
            if (next_put == cdc->rx_buf_get) {
                // overflow, we just discard the rest of the chars
                break;
            }
            cdc->rx_user_buf[cdc->rx_buf_put] = *src;
            cdc->rx_buf_put = next_put;
        }
    }

    // initiate next USB packet transfer
    USBD_CDC_ReceivePacket(cdc->usbd, cdc->rx_packet_buf);

    return USBD_OK;
}

int usbd_cdc_tx_half_empty(usbd_cdc_itf_t *cdc) {
    int32_t tx_waiting = (int32_t)cdc->tx_buf_ptr_in - (int32_t)cdc->tx_buf_ptr_out;
    if (tx_waiting < 0) {
        tx_waiting += USBD_CDC_TX_DATA_SIZE;
    }
    return tx_waiting <= USBD_CDC_TX_DATA_SIZE / 2;
}

// timout in milliseconds.
// Returns number of bytes written to the device.
int usbd_cdc_tx(usbd_cdc_itf_t *cdc, const uint8_t *buf, uint32_t len, uint32_t timeout) {
    for (uint32_t i = 0; i < len; i++) {
        // Wait until the device is connected and the buffer has space, with a given timeout
        uint32_t start = HAL_GetTick();
        while (!cdc->dev_is_connected || ((cdc->tx_buf_ptr_in + 1) & (USBD_CDC_TX_DATA_SIZE - 1)) == cdc->tx_buf_ptr_out) {
            // Wraparound of tick is taken care of by 2's complement arithmetic.
            if (HAL_GetTick() - start >= timeout) {
                // timeout
                return i;
            }
            if (query_irq() == IRQ_STATE_DISABLED) {
                // IRQs disabled so buffer will never be drained; return immediately
                return i;
            }
            __WFI(); // enter sleep mode, waiting for interrupt
        }

        // Write data to device buffer
        cdc->tx_buf[cdc->tx_buf_ptr_in] = buf[i];
        cdc->tx_buf_ptr_in = (cdc->tx_buf_ptr_in + 1) & (USBD_CDC_TX_DATA_SIZE - 1);
    }

    // Success, return number of bytes read
    return len;
}

// Always write all of the data to the device tx buffer, even if the
// device is not connected, or if the buffer is full.  Has a small timeout
// to wait for the buffer to be drained, in the case the device is connected.
void usbd_cdc_tx_always(usbd_cdc_itf_t *cdc, const uint8_t *buf, uint32_t len) {
    for (int i = 0; i < len; i++) {
        // If the CDC device is not connected to the host then we don't have anyone to receive our data.
        // The device may become connected in the future, so we should at least try to fill the buffer
        // and hope that it doesn't overflow by the time the device connects.
        // If the device is not connected then we should go ahead and fill the buffer straight away,
        // ignoring overflow.  Otherwise, we should make sure that we have enough room in the buffer.
        if (cdc->dev_is_connected) {
            // If the buffer is full, wait until it gets drained, with a timeout of 500ms
            // (wraparound of tick is taken care of by 2's complement arithmetic).
            uint32_t start = HAL_GetTick();
            while (((cdc->tx_buf_ptr_in + 1) & (USBD_CDC_TX_DATA_SIZE - 1)) == cdc->tx_buf_ptr_out && HAL_GetTick() - start <= 500) {
                if (query_irq() == IRQ_STATE_DISABLED) {
                    // IRQs disabled so buffer will never be drained; exit loop
                    break;
                }
                __WFI(); // enter sleep mode, waiting for interrupt
            }

            // Some unused code that makes sure the low-level USB buffer is drained.
            // Waiting for low-level is handled in HAL_PCD_SOFCallback.
            /*
            start = HAL_GetTick();
            PCD_HandleTypeDef *hpcd = hUSBDDevice.pData;
            if (hpcd->IN_ep[0x83 & 0x7f].is_in) {
                //volatile uint32_t *xfer_count = &hpcd->IN_ep[0x83 & 0x7f].xfer_count;
                //volatile uint32_t *xfer_len = &hpcd->IN_ep[0x83 & 0x7f].xfer_len;
                USB_OTG_GlobalTypeDef *USBx = hpcd->Instance;
                while (
                    // *xfer_count < *xfer_len // using this works
                    // (USBx_INEP(3)->DIEPTSIZ & USB_OTG_DIEPTSIZ_XFRSIZ) // using this works
                    && HAL_GetTick() - start <= 2000) {
                    __WFI(); // enter sleep mode, waiting for interrupt
                }
            }
            */
        }

        cdc->tx_buf[cdc->tx_buf_ptr_in] = buf[i];
        cdc->tx_buf_ptr_in = (cdc->tx_buf_ptr_in + 1) & (USBD_CDC_TX_DATA_SIZE - 1);
    }
}

// Returns number of bytes in the rx buffer.
int usbd_cdc_rx_num(usbd_cdc_itf_t *cdc) {
    int32_t rx_waiting = (int32_t)cdc->rx_buf_put - (int32_t)cdc->rx_buf_get;
    if (rx_waiting < 0) {
        rx_waiting += USBD_CDC_RX_DATA_SIZE;
    }
    return rx_waiting;
}

// timout in milliseconds.
// Returns number of bytes read from the device.
int usbd_cdc_rx(usbd_cdc_itf_t *cdc, uint8_t *buf, uint32_t len, uint32_t timeout) {
    // loop to read bytes
    for (uint32_t i = 0; i < len; i++) {
        // Wait until we have at least 1 byte to read
        uint32_t start = HAL_GetTick();
        while (cdc->rx_buf_put == cdc->rx_buf_get) {
            // Wraparound of tick is taken care of by 2's complement arithmetic.
            if (HAL_GetTick() - start >= timeout) {
                // timeout
                return i;
            }
            if (query_irq() == IRQ_STATE_DISABLED) {
                // IRQs disabled so buffer will never be filled; return immediately
                return i;
            }
            __WFI(); // enter sleep mode, waiting for interrupt
        }

        // Copy byte from device to user buffer
        buf[i] = cdc->rx_user_buf[cdc->rx_buf_get];
        cdc->rx_buf_get = (cdc->rx_buf_get + 1) & (USBD_CDC_RX_DATA_SIZE - 1);
    }

    // Success, return number of bytes read
    return len;
}