// SPDX-License-Identifier: GPL-2.0+
/*
 *  REINER SCT cyberJack pinpad/e-com USB Chipcard Reader Driver
 *
 *  Copyright (C) 2001  REINER SCT
 *  Author: Matthias Bruestle
 *
 *  Contact: support@reiner-sct.com (see MAINTAINERS)
 *
 *  This program is largely derived from work by the linux-usb group
 *  and associated source files.  Please see the usb/serial files for
 *  individual credits and copyrights.
 *
 *  Thanks to Greg Kroah-Hartman (greg@kroah.com) for his help and
 *  patience.
 *
 *  In case of problems, please write to the contact e-mail address
 *  mentioned above.
 *
 *  Please note that later models of the cyberjack reader family are
 *  supported by a libusb-based userspace device driver.
 *
 *  Homepage: http://www.reiner-sct.de/support/treiber_cyberjack.php#linux
 */


#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>

#define CYBERJACK_LOCAL_BUF_SIZE 32

#define DRIVER_AUTHOR "Matthias Bruestle"
#define DRIVER_DESC "REINER SCT cyberJack pinpad/e-com USB Chipcard Reader Driver"


#define CYBERJACK_VENDOR_ID     0x0C4B
#define CYBERJACK_PRODUCT_ID    0x0100

/* Function prototypes */
static int cyberjack_port_probe(struct usb_serial_port *port);
static int cyberjack_port_remove(struct usb_serial_port *port);
static int  cyberjack_open(struct tty_struct *tty,
        struct usb_serial_port *port);
static void cyberjack_close(struct usb_serial_port *port);
static int cyberjack_write(struct tty_struct *tty,
        struct usb_serial_port *port, const unsigned char *buf, int count);
static int cyberjack_write_room(struct tty_struct *tty);
static void cyberjack_read_int_callback(struct urb *urb);
static void cyberjack_read_bulk_callback(struct urb *urb);
static void cyberjack_write_bulk_callback(struct urb *urb);

static const struct usb_device_id id_table[] = {
        { USB_DEVICE(CYBERJACK_VENDOR_ID, CYBERJACK_PRODUCT_ID) },
        { }                     /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, id_table);

static struct usb_serial_driver cyberjack_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "cyberjack",
        },
        .description =          "Reiner SCT Cyberjack USB card reader",
        .id_table =             id_table,
        .num_ports =            1,
        .num_bulk_out =         1,
        .port_probe =           cyberjack_port_probe,
        .port_remove =          cyberjack_port_remove,
        .open =                 cyberjack_open,
        .close =                cyberjack_close,
        .write =                cyberjack_write,
        .write_room =           cyberjack_write_room,
        .read_int_callback =    cyberjack_read_int_callback,
        .read_bulk_callback =   cyberjack_read_bulk_callback,
        .write_bulk_callback =  cyberjack_write_bulk_callback,
};

static struct usb_serial_driver * const serial_drivers[] = {
        &cyberjack_device, NULL
};

struct cyberjack_private {
        spinlock_t      lock;           /* Lock for SMP */
        short           rdtodo;         /* Bytes still to read */
        unsigned char   wrbuf[5*64];    /* Buffer for collecting data to write */
        short           wrfilled;       /* Overall data size we already got */
        short           wrsent;         /* Data already sent */
};

static int cyberjack_port_probe(struct usb_serial_port *port)
{
        struct cyberjack_private *priv;
        int result;

        priv = kmalloc(sizeof(struct cyberjack_private), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        spin_lock_init(&priv->lock);
        priv->rdtodo = 0;
        priv->wrfilled = 0;
        priv->wrsent = 0;

        usb_set_serial_port_data(port, priv);

        result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
        if (result)
                dev_err(&port->dev, "usb_submit_urb(read int) failed\n");

        return 0;
}

static int cyberjack_port_remove(struct usb_serial_port *port)
{
        struct cyberjack_private *priv;

        usb_kill_urb(port->interrupt_in_urb);

        priv = usb_get_serial_port_data(port);
        kfree(priv);

        return 0;
}

static int  cyberjack_open(struct tty_struct *tty,
                                        struct usb_serial_port *port)
{
        struct cyberjack_private *priv;
        unsigned long flags;

        dev_dbg(&port->dev, "%s - usb_clear_halt\n", __func__);
        usb_clear_halt(port->serial->dev, port->write_urb->pipe);

        priv = usb_get_serial_port_data(port);
        spin_lock_irqsave(&priv->lock, flags);
        priv->rdtodo = 0;
        priv->wrfilled = 0;
        priv->wrsent = 0;
        spin_unlock_irqrestore(&priv->lock, flags);

        return 0;
}

static void cyberjack_close(struct usb_serial_port *port)
{
        usb_kill_urb(port->write_urb);
        usb_kill_urb(port->read_urb);
}

static int cyberjack_write(struct tty_struct *tty,
        struct usb_serial_port *port, const unsigned char *buf, int count)
{
        struct device *dev = &port->dev;
        struct cyberjack_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        int result;
        int wrexpected;

        if (count == 0) {
                dev_dbg(dev, "%s - write request of 0 bytes\n", __func__);
                return 0;
        }

        if (!test_and_clear_bit(0, &port->write_urbs_free)) {
                dev_dbg(dev, "%s - already writing\n", __func__);
                return 0;
        }

        spin_lock_irqsave(&priv->lock, flags);

        if (count+priv->wrfilled > sizeof(priv->wrbuf)) {
                /* To much data for buffer. Reset buffer. */
                priv->wrfilled = 0;
                spin_unlock_irqrestore(&priv->lock, flags);
                set_bit(0, &port->write_urbs_free);
                return 0;
        }

        /* Copy data */
        memcpy(priv->wrbuf + priv->wrfilled, buf, count);

        usb_serial_debug_data(dev, __func__, count, priv->wrbuf + priv->wrfilled);
        priv->wrfilled += count;

        if (priv->wrfilled >= 3) {
                wrexpected = ((int)priv->wrbuf[2]<<8)+priv->wrbuf[1]+3;
                dev_dbg(dev, "%s - expected data: %d\n", __func__, wrexpected);
        } else
                wrexpected = sizeof(priv->wrbuf);

        if (priv->wrfilled >= wrexpected) {
                /* We have enough data to begin transmission */
                int length;

                dev_dbg(dev, "%s - transmitting data (frame 1)\n", __func__);
                length = (wrexpected > port->bulk_out_size) ?
                                        port->bulk_out_size : wrexpected;

                memcpy(port->write_urb->transfer_buffer, priv->wrbuf, length);
                priv->wrsent = length;

                /* set up our urb */
                port->write_urb->transfer_buffer_length = length;

                /* send the data out the bulk port */
                result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
                if (result) {
                        dev_err(&port->dev,
                                "%s - failed submitting write urb, error %d\n",
                                __func__, result);
                        /* Throw away data. No better idea what to do with it. */
                        priv->wrfilled = 0;
                        priv->wrsent = 0;
                        spin_unlock_irqrestore(&priv->lock, flags);
                        set_bit(0, &port->write_urbs_free);
                        return 0;
                }

                dev_dbg(dev, "%s - priv->wrsent=%d\n", __func__, priv->wrsent);
                dev_dbg(dev, "%s - priv->wrfilled=%d\n", __func__, priv->wrfilled);

                if (priv->wrsent >= priv->wrfilled) {
                        dev_dbg(dev, "%s - buffer cleaned\n", __func__);
                        memset(priv->wrbuf, 0, sizeof(priv->wrbuf));
                        priv->wrfilled = 0;
                        priv->wrsent = 0;
                }
        }

        spin_unlock_irqrestore(&priv->lock, flags);

        return count;
}

static int cyberjack_write_room(struct tty_struct *tty)
{
        /* FIXME: .... */
        return CYBERJACK_LOCAL_BUF_SIZE;
}

static void cyberjack_read_int_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct cyberjack_private *priv = usb_get_serial_port_data(port);
        struct device *dev = &port->dev;
        unsigned char *data = urb->transfer_buffer;
        int status = urb->status;
        unsigned long flags;
        int result;

        /* the urb might have been killed. */
        if (status)
                return;

        usb_serial_debug_data(dev, __func__, urb->actual_length, data);

        /* React only to interrupts signaling a bulk_in transfer */
        if (urb->actual_length == 4 && data[0] == 0x01) {
                short old_rdtodo;

                /* This is a announcement of coming bulk_ins. */
                unsigned short size = ((unsigned short)data[3]<<8)+data[2]+3;

                spin_lock_irqsave(&priv->lock, flags);

                old_rdtodo = priv->rdtodo;

                if (old_rdtodo > SHRT_MAX - size) {
                        dev_dbg(dev, "To many bulk_in urbs to do.\n");
                        spin_unlock_irqrestore(&priv->lock, flags);
                        goto resubmit;
                }

                /* "+=" is probably more fault tolerant than "=" */
                priv->rdtodo += size;

                dev_dbg(dev, "%s - rdtodo: %d\n", __func__, priv->rdtodo);

                spin_unlock_irqrestore(&priv->lock, flags);

                if (!old_rdtodo) {
                        result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
                        if (result)
                                dev_err(dev, "%s - failed resubmitting read urb, error %d\n",
                                        __func__, result);
                        dev_dbg(dev, "%s - usb_submit_urb(read urb)\n", __func__);
                }
        }

resubmit:
        result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
        if (result)
                dev_err(&port->dev, "usb_submit_urb(read int) failed\n");
        dev_dbg(dev, "%s - usb_submit_urb(int urb)\n", __func__);
}

static void cyberjack_read_bulk_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct cyberjack_private *priv = usb_get_serial_port_data(port);
        struct device *dev = &port->dev;
        unsigned char *data = urb->transfer_buffer;
        unsigned long flags;
        short todo;
        int result;
        int status = urb->status;

        usb_serial_debug_data(dev, __func__, urb->actual_length, data);
        if (status) {
                dev_dbg(dev, "%s - nonzero read bulk status received: %d\n",
                        __func__, status);
                return;
        }

        if (urb->actual_length) {
                tty_insert_flip_string(&port->port, data, urb->actual_length);
                tty_flip_buffer_push(&port->port);
        }

        spin_lock_irqsave(&priv->lock, flags);

        /* Reduce urbs to do by one. */
        priv->rdtodo -= urb->actual_length;
        /* Just to be sure */
        if (priv->rdtodo < 0)
                priv->rdtodo = 0;
        todo = priv->rdtodo;

        spin_unlock_irqrestore(&priv->lock, flags);

        dev_dbg(dev, "%s - rdtodo: %d\n", __func__, todo);

        /* Continue to read if we have still urbs to do. */
        if (todo /* || (urb->actual_length==port->bulk_in_endpointAddress)*/) {
                result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
                if (result)
                        dev_err(dev, "%s - failed resubmitting read urb, error %d\n",
                                __func__, result);
                dev_dbg(dev, "%s - usb_submit_urb(read urb)\n", __func__);
        }
}

static void cyberjack_write_bulk_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct cyberjack_private *priv = usb_get_serial_port_data(port);
        struct device *dev = &port->dev;
        int status = urb->status;
        unsigned long flags;

        set_bit(0, &port->write_urbs_free);
        if (status) {
                dev_dbg(dev, "%s - nonzero write bulk status received: %d\n",
                        __func__, status);
                return;
        }

        spin_lock_irqsave(&priv->lock, flags);

        /* only do something if we have more data to send */
        if (priv->wrfilled) {
                int length, blksize, result;

                dev_dbg(dev, "%s - transmitting data (frame n)\n", __func__);

                length = ((priv->wrfilled - priv->wrsent) > port->bulk_out_size) ?
                        port->bulk_out_size : (priv->wrfilled - priv->wrsent);

                memcpy(port->write_urb->transfer_buffer,
                                        priv->wrbuf + priv->wrsent, length);
                priv->wrsent += length;

                /* set up our urb */
                port->write_urb->transfer_buffer_length = length;

                /* send the data out the bulk port */
                result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
                if (result) {
                        dev_err(dev, "%s - failed submitting write urb, error %d\n",
                                __func__, result);
                        /* Throw away data. No better idea what to do with it. */
                        priv->wrfilled = 0;
                        priv->wrsent = 0;
                        goto exit;
                }

                dev_dbg(dev, "%s - priv->wrsent=%d\n", __func__, priv->wrsent);
                dev_dbg(dev, "%s - priv->wrfilled=%d\n", __func__, priv->wrfilled);

                blksize = ((int)priv->wrbuf[2]<<8)+priv->wrbuf[1]+3;

                if (priv->wrsent >= priv->wrfilled ||
                                        priv->wrsent >= blksize) {
                        dev_dbg(dev, "%s - buffer cleaned\n", __func__);
                        memset(priv->wrbuf, 0, sizeof(priv->wrbuf));
                        priv->wrfilled = 0;
                        priv->wrsent = 0;
                }
        }

exit:
        spin_unlock_irqrestore(&priv->lock, flags);
        usb_serial_port_softint(port);
}

module_usb_serial_driver(serial_drivers, id_table);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");