pios_usb_cdc.c

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/*
 * 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/>
 */

/* Project Includes */
#include "pios.h"

#if defined(PIOS_INCLUDE_USB_CDC)

#include "pios_usb.h"
#include "pios_usb_cdc_priv.h"
#include "pios_usb_board_data.h" /* PIOS_BOARD_*_DATA_LENGTH */

/* STM32 USB Library Definitions */
#include "usb_lib.h"

static void PIOS_USB_CDC_RegisterTxCallback(uintptr_t usbcdc_id, pios_com_callback tx_out_cb, uintptr_t context);
static void PIOS_USB_CDC_RegisterRxCallback(uintptr_t usbcdc_id, pios_com_callback rx_in_cb, uintptr_t context);
static void PIOS_USB_CDC_TxStart(uintptr_t usbcdc_id, uint16_t tx_bytes_avail);
static void PIOS_USB_CDC_RxStart(uintptr_t usbcdc_id, uint16_t rx_bytes_avail);
static bool PIOS_USB_CDC_Available (uintptr_t usbcdc_id);

const struct pios_com_driver pios_usb_cdc_com_driver = {
        .tx_start    = PIOS_USB_CDC_TxStart,
        .rx_start    = PIOS_USB_CDC_RxStart,
        .bind_tx_cb  = PIOS_USB_CDC_RegisterTxCallback,
        .bind_rx_cb  = PIOS_USB_CDC_RegisterRxCallback,
        .available   = PIOS_USB_CDC_Available,
};

enum pios_usb_cdc_dev_magic {
        PIOS_USB_CDC_DEV_MAGIC = 0xAABBCCDD,
};

struct pios_usb_cdc_dev {
        enum pios_usb_cdc_dev_magic     magic;
        const struct pios_usb_cdc_cfg * cfg;

        uintptr_t lower_id;

        pios_com_callback rx_in_cb;
        uintptr_t rx_in_context;
        pios_com_callback tx_out_cb;
        uintptr_t tx_out_context;

        uint8_t rx_packet_buffer[PIOS_USB_BOARD_CDC_DATA_LENGTH];
        /*
         * NOTE: This is -1 as somewhat of a hack.  It ensures that we always send packets
         * that are strictly < maxPacketSize for this interface which means we never have
         * to bother with zero length packets (ZLP).
         */
        uint8_t tx_packet_buffer[PIOS_USB_BOARD_CDC_DATA_LENGTH - 1];

        uint32_t rx_dropped;
        uint32_t rx_oversize;
};

static bool PIOS_USB_CDC_validate(struct pios_usb_cdc_dev * usb_cdc_dev)
{
        return (usb_cdc_dev->magic == PIOS_USB_CDC_DEV_MAGIC);
}

static struct pios_usb_cdc_dev * PIOS_USB_CDC_alloc(void)
{
        struct pios_usb_cdc_dev * usb_cdc_dev;

        usb_cdc_dev = (struct pios_usb_cdc_dev *)PIOS_malloc(sizeof(*usb_cdc_dev));
        if (!usb_cdc_dev) return(NULL);

        memset(usb_cdc_dev, 0, sizeof(*usb_cdc_dev));
        usb_cdc_dev->magic = PIOS_USB_CDC_DEV_MAGIC;
        return(usb_cdc_dev);
}

static void PIOS_USB_CDC_DATA_EP_IN_Callback(void);
static void PIOS_USB_CDC_DATA_EP_OUT_Callback(void);
static void PIOS_USB_CDC_CTRL_EP_IN_Callback(void);

static uintptr_t pios_usb_cdc_id;

/* Need a better way to pull these in */
extern void (*pEpInt_IN[7])(void);
extern void (*pEpInt_OUT[7])(void);

int32_t PIOS_USB_CDC_Init(uintptr_t * usbcdc_id, const struct pios_usb_cdc_cfg * cfg, uintptr_t lower_id)
{
        PIOS_Assert(usbcdc_id);
        PIOS_Assert(cfg);

        struct pios_usb_cdc_dev * usb_cdc_dev;

        usb_cdc_dev = (struct pios_usb_cdc_dev *) PIOS_USB_CDC_alloc();
        if (!usb_cdc_dev) goto out_fail;

        /* Bind the configuration to the device instance */
        usb_cdc_dev->cfg = cfg;
        usb_cdc_dev->lower_id = lower_id;

        pios_usb_cdc_id = (uintptr_t) usb_cdc_dev;

        /* Bind lower level callbacks into the USB infrastructure */
        pEpInt_OUT[cfg->ctrl_tx_ep - 1] = PIOS_USB_CDC_CTRL_EP_IN_Callback;
        pEpInt_IN[cfg->data_tx_ep - 1] = PIOS_USB_CDC_DATA_EP_IN_Callback;
        pEpInt_OUT[cfg->data_rx_ep - 1] = PIOS_USB_CDC_DATA_EP_OUT_Callback;

        *usbcdc_id = (uintptr_t) usb_cdc_dev;

        return 0;

out_fail:
        return -1;
}



static void PIOS_USB_CDC_RegisterRxCallback(uintptr_t usbcdc_id, pios_com_callback rx_in_cb, uintptr_t context)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)usbcdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        PIOS_Assert(valid);

        /* 
         * Order is important in these assignments since ISR uses _cb
         * field to determine if it's ok to dereference _cb and _context
         */
        usb_cdc_dev->rx_in_context = context;
        usb_cdc_dev->rx_in_cb = rx_in_cb;
}

static void PIOS_USB_CDC_RegisterTxCallback(uintptr_t usbcdc_id, pios_com_callback tx_out_cb, uintptr_t context)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)usbcdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        PIOS_Assert(valid);

        /* 
         * Order is important in these assignments since ISR uses _cb
         * field to determine if it's ok to dereference _cb and _context
         */
        usb_cdc_dev->tx_out_context = context;
        usb_cdc_dev->tx_out_cb = tx_out_cb;
}

static void PIOS_USB_CDC_RxStart(uintptr_t usbcdc_id, uint16_t rx_bytes_avail) {
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)usbcdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        PIOS_Assert(valid);

        if (!PIOS_USB_CheckAvailable(usb_cdc_dev->lower_id)) {
                return;
        }

        // If endpoint was stalled and there is now space make it valid
        PIOS_IRQ_Disable();
        if ((GetEPRxStatus(usb_cdc_dev->cfg->data_rx_ep) != EP_RX_VALID) && 
                (rx_bytes_avail >= sizeof(usb_cdc_dev->rx_packet_buffer))) {
                SetEPRxStatus(usb_cdc_dev->cfg->data_rx_ep, EP_RX_VALID);
        }
        PIOS_IRQ_Enable();
}

static void PIOS_USB_CDC_SendData(struct pios_usb_cdc_dev * usb_cdc_dev)
{
        uint16_t bytes_to_tx;

        if (!usb_cdc_dev->tx_out_cb) {
                return;
        }

        bool need_yield = false;
        bytes_to_tx = (usb_cdc_dev->tx_out_cb)(usb_cdc_dev->tx_out_context,
                                               usb_cdc_dev->tx_packet_buffer,
                                               sizeof(usb_cdc_dev->tx_packet_buffer),
                                               NULL,
                                               &need_yield);
        if (bytes_to_tx == 0) {
                return;
        }

        UserToPMABufferCopy(usb_cdc_dev->tx_packet_buffer,
                        GetEPTxAddr(usb_cdc_dev->cfg->data_tx_ep),
                        bytes_to_tx);
        SetEPTxCount(usb_cdc_dev->cfg->data_tx_ep, bytes_to_tx);
        SetEPTxValid(usb_cdc_dev->cfg->data_tx_ep);
}

static void PIOS_USB_CDC_TxStart(uintptr_t usbcdc_id, uint16_t tx_bytes_avail)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)usbcdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        PIOS_Assert(valid);

        if (!PIOS_USB_CheckAvailable(usb_cdc_dev->lower_id)) {
                return;
        }

        if (GetEPTxStatus(usb_cdc_dev->cfg->data_tx_ep) == EP_TX_VALID) {
                /* Endpoint is already transmitting */
                return;
        }

        PIOS_USB_CDC_SendData(usb_cdc_dev);
}

static void PIOS_USB_CDC_DATA_EP_IN_Callback(void)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)pios_usb_cdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        PIOS_Assert(valid);

        PIOS_USB_CDC_SendData(usb_cdc_dev);
}

static void PIOS_USB_CDC_DATA_EP_OUT_Callback(void)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)pios_usb_cdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        PIOS_Assert(valid);

        uint32_t DataLength;

        /* Get the number of received data on the selected Endpoint */
        DataLength = GetEPRxCount(usb_cdc_dev->cfg->data_rx_ep);
        if (DataLength > sizeof(usb_cdc_dev->rx_packet_buffer)) {
                usb_cdc_dev->rx_oversize++;
                DataLength = sizeof(usb_cdc_dev->rx_packet_buffer);
        }

        /* Use the memory interface function to read from the selected endpoint */
        PMAToUserBufferCopy((uint8_t *) usb_cdc_dev->rx_packet_buffer,
                        GetEPRxAddr(usb_cdc_dev->cfg->data_rx_ep),
                        DataLength);

        if (!usb_cdc_dev->rx_in_cb) {
                /* No Rx call back registered, disable the receiver */
                SetEPRxStatus(usb_cdc_dev->cfg->data_rx_ep, EP_RX_NAK);
                return;
        }

        uint16_t headroom;
        bool need_yield = false;
        uint16_t rc;
        rc = (usb_cdc_dev->rx_in_cb)(usb_cdc_dev->rx_in_context,
                                usb_cdc_dev->rx_packet_buffer,
                                DataLength,
                                &headroom,
                                &need_yield);

        if (rc < DataLength) {
                /* Lost bytes on rx */
                usb_cdc_dev->rx_dropped += (DataLength - rc);
        }

        if (headroom >= sizeof(usb_cdc_dev->rx_packet_buffer)) {
                /* We have room for a maximum length message */
                SetEPRxStatus(usb_cdc_dev->cfg->data_rx_ep, EP_RX_VALID);
        } else {
                /* Not enough room left for a message, apply backpressure */
                SetEPRxStatus(usb_cdc_dev->cfg->data_rx_ep, EP_RX_NAK);
        }
}

static uint16_t control_line_state;
RESULT PIOS_USB_CDC_SetControlLineState(void)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)pios_usb_cdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        if (!valid) {
                /* No CDC interface is configured */
                return USB_UNSUPPORT;
        }

        uint8_t wValue0 = pInformation->USBwValue0;
        uint8_t wValue1 = pInformation->USBwValue1;

        control_line_state = wValue1 << 8 | wValue0;

        return USB_SUCCESS;
}

static bool PIOS_USB_CDC_Available (uintptr_t usbcdc_id)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)usbcdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        PIOS_Assert(valid);

        return PIOS_USB_CheckAvailable(usb_cdc_dev->lower_id);
}

static struct usb_cdc_line_coding line_coding = {
        .dwDTERate   = htousbl(57600),
        .bCharFormat = USB_CDC_LINE_CODING_STOP_1,
        .bParityType = USB_CDC_LINE_CODING_PARITY_NONE,
        .bDataBits   = 8,
};

uint8_t *PIOS_USB_CDC_SetLineCoding(uint16_t Length)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)pios_usb_cdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        if (!valid) {
                /* No CDC interface is configured */
                return NULL;
        }

        if (Length == 0) {
                /* Report the number of bytes we're prepared to consume */
                pInformation->Ctrl_Info.Usb_wLength = sizeof(line_coding);
                pInformation->Ctrl_Info.Usb_rLength = sizeof(line_coding);
                return NULL;
        } else {
                /* Give out a pointer to the data struct */
                return ((uint8_t *) &line_coding);
        }
}

const uint8_t *PIOS_USB_CDC_GetLineCoding(uint16_t Length)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)pios_usb_cdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        if (!valid) {
                /* No CDC interface is configured */
                return NULL;
        }

        if (Length == 0) {
                pInformation->Ctrl_Info.Usb_wLength = sizeof(line_coding);
                return NULL;
        } else {
                return ((uint8_t *) &line_coding);
        }
}

const struct usb_cdc_serial_state_report uart_state = {
        .bmRequestType = 0xA1,
        .bNotification = USB_CDC_NOTIFICATION_SERIAL_STATE,
        .wValue        = 0,
        .wIndex        = htousbs(1),
        .wLength       = htousbs(2),
        .bmUartState   = htousbs(2 /* DSR */ | 1 /* DCD */),
};
        
static void PIOS_USB_CDC_CTRL_EP_IN_Callback(void)
{
        struct pios_usb_cdc_dev * usb_cdc_dev = (struct pios_usb_cdc_dev *)pios_usb_cdc_id;

        bool valid = PIOS_USB_CDC_validate(usb_cdc_dev);
        PIOS_Assert(valid);

        UserToPMABufferCopy((const uint8_t *) &uart_state,
                        GetEPTxAddr(usb_cdc_dev->cfg->ctrl_tx_ep),
                        sizeof(uart_state));

        SetEPTxCount(usb_cdc_dev->cfg->ctrl_tx_ep, PIOS_USB_BOARD_CDC_MGMT_LENGTH);
        SetEPTxValid(usb_cdc_dev->cfg->ctrl_tx_ep);
}

#endif  /* PIOS_INCLUDE_USB_CDC */