// SPDX-License-Identifier: GPL-2.0
/*
 * Opticon USB barcode to serial driver
 *
 * Copyright (C) 2011 - 2012 Johan Hovold <jhovold@gmail.com>
 * Copyright (C) 2011 Martin Jansen <martin.jansen@opticon.com>
 * Copyright (C) 2008 - 2009 Greg Kroah-Hartman <gregkh@suse.de>
 * Copyright (C) 2008 - 2009 Novell Inc.
 */

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

#define CONTROL_RTS                     0x02
#define RESEND_CTS_STATE        0x03

/* max number of write urbs in flight */
#define URB_UPPER_LIMIT 8

/* This driver works for the Opticon 1D barcode reader
 * an examples of 1D barcode types are EAN, UPC, Code39, IATA etc.. */
#define DRIVER_DESC     "Opticon USB barcode to serial driver (1D)"

static const struct usb_device_id id_table[] = {
        { USB_DEVICE(0x065a, 0x0009) },
        { },
};
MODULE_DEVICE_TABLE(usb, id_table);

/* This structure holds all of the individual device information */
struct opticon_private {
        spinlock_t lock;        /* protects the following flags */
        bool rts;
        bool cts;
        int outstanding_urbs;
        int outstanding_bytes;

        struct usb_anchor anchor;
};


static void opticon_process_data_packet(struct usb_serial_port *port,
                                        const unsigned char *buf, size_t len)
{
        tty_insert_flip_string(&port->port, buf, len);
        tty_flip_buffer_push(&port->port);
}

static void opticon_process_status_packet(struct usb_serial_port *port,
                                        const unsigned char *buf, size_t len)
{
        struct opticon_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);
        if (buf[0] == 0x00)
                priv->cts = false;
        else
                priv->cts = true;
        spin_unlock_irqrestore(&priv->lock, flags);
}

static void opticon_process_read_urb(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        const unsigned char *hdr = urb->transfer_buffer;
        const unsigned char *data = hdr + 2;
        size_t data_len = urb->actual_length - 2;

        if (urb->actual_length <= 2) {
                dev_dbg(&port->dev, "malformed packet received: %d bytes\n",
                                                        urb->actual_length);
                return;
        }
        /*
         * Data from the device comes with a 2 byte header:
         *
         * <0x00><0x00>data...
         *      This is real data to be sent to the tty layer
         * <0x00><0x01>level
         *      This is a CTS level change, the third byte is the CTS
         *      value (0 for low, 1 for high).
         */
        if ((hdr[0] == 0x00) && (hdr[1] == 0x00)) {
                opticon_process_data_packet(port, data, data_len);
        } else if ((hdr[0] == 0x00) && (hdr[1] == 0x01)) {
                opticon_process_status_packet(port, data, data_len);
        } else {
                dev_dbg(&port->dev, "unknown packet received: %02x %02x\n",
                                                        hdr[0], hdr[1]);
        }
}

static int send_control_msg(struct usb_serial_port *port, u8 requesttype,
                                u8 val)
{
        struct usb_serial *serial = port->serial;
        int retval;
        u8 *buffer;

        buffer = kzalloc(1, GFP_KERNEL);
        if (!buffer)
                return -ENOMEM;

        buffer[0] = val;
        /* Send the message to the vendor control endpoint
         * of the connected device */
        retval = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                                requesttype,
                                USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
                                0, 0, buffer, 1, USB_CTRL_SET_TIMEOUT);
        kfree(buffer);

        if (retval < 0)
                return retval;

        return 0;
}

static int opticon_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct opticon_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        int res;

        spin_lock_irqsave(&priv->lock, flags);
        priv->rts = false;
        spin_unlock_irqrestore(&priv->lock, flags);

        /* Clear RTS line */
        send_control_msg(port, CONTROL_RTS, 0);

        /* clear the halt status of the endpoint */
        usb_clear_halt(port->serial->dev, port->read_urb->pipe);

        res = usb_serial_generic_open(tty, port);
        if (res)
                return res;

        /* Request CTS line state, sometimes during opening the current
         * CTS state can be missed. */
        send_control_msg(port, RESEND_CTS_STATE, 1);

        return res;
}

static void opticon_close(struct usb_serial_port *port)
{
        struct opticon_private *priv = usb_get_serial_port_data(port);

        usb_kill_anchored_urbs(&priv->anchor);

        usb_serial_generic_close(port);
}

static void opticon_write_control_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct opticon_private *priv = usb_get_serial_port_data(port);
        int status = urb->status;
        unsigned long flags;

        /* free up the transfer buffer, as usb_free_urb() does not do this */
        kfree(urb->transfer_buffer);

        /* setup packet may be set if we're using it for writing */
        kfree(urb->setup_packet);

        if (status)
                dev_dbg(&port->dev,
                        "%s - non-zero urb status received: %d\n",
                        __func__, status);

        spin_lock_irqsave(&priv->lock, flags);
        --priv->outstanding_urbs;
        priv->outstanding_bytes -= urb->transfer_buffer_length;
        spin_unlock_irqrestore(&priv->lock, flags);

        usb_serial_port_softint(port);
}

static int opticon_write(struct tty_struct *tty, struct usb_serial_port *port,
                         const unsigned char *buf, int count)
{
        struct opticon_private *priv = usb_get_serial_port_data(port);
        struct usb_serial *serial = port->serial;
        struct urb *urb;
        unsigned char *buffer;
        unsigned long flags;
        struct usb_ctrlrequest *dr;
        int ret = -ENOMEM;

        spin_lock_irqsave(&priv->lock, flags);
        if (priv->outstanding_urbs > URB_UPPER_LIMIT) {
                spin_unlock_irqrestore(&priv->lock, flags);
                dev_dbg(&port->dev, "%s - write limit hit\n", __func__);
                return 0;
        }
        priv->outstanding_urbs++;
        priv->outstanding_bytes += count;
        spin_unlock_irqrestore(&priv->lock, flags);

        buffer = kmalloc(count, GFP_ATOMIC);
        if (!buffer)
                goto error_no_buffer;

        urb = usb_alloc_urb(0, GFP_ATOMIC);
        if (!urb)
                goto error_no_urb;

        memcpy(buffer, buf, count);

        usb_serial_debug_data(&port->dev, __func__, count, buffer);

        /* The connected devices do not have a bulk write endpoint,
         * to transmit data to de barcode device the control endpoint is used */
        dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
        if (!dr)
                goto error_no_dr;

        dr->bRequestType = USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_OUT;
        dr->bRequest = 0x01;
        dr->wValue = 0;
        dr->wIndex = 0;
        dr->wLength = cpu_to_le16(count);

        usb_fill_control_urb(urb, serial->dev,
                usb_sndctrlpipe(serial->dev, 0),
                (unsigned char *)dr, buffer, count,
                opticon_write_control_callback, port);

        usb_anchor_urb(urb, &priv->anchor);

        /* send it down the pipe */
        ret = usb_submit_urb(urb, GFP_ATOMIC);
        if (ret) {
                dev_err(&port->dev, "failed to submit write urb: %d\n", ret);
                usb_unanchor_urb(urb);
                goto error;
        }

        /* we are done with this urb, so let the host driver
         * really free it when it is finished with it */
        usb_free_urb(urb);

        return count;
error:
        kfree(dr);
error_no_dr:
        usb_free_urb(urb);
error_no_urb:
        kfree(buffer);
error_no_buffer:
        spin_lock_irqsave(&priv->lock, flags);
        --priv->outstanding_urbs;
        priv->outstanding_bytes -= count;
        spin_unlock_irqrestore(&priv->lock, flags);

        return ret;
}

static unsigned int opticon_write_room(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct opticon_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;

        /*
         * We really can take almost anything the user throws at us
         * but let's pick a nice big number to tell the tty
         * layer that we have lots of free space, unless we don't.
         */
        spin_lock_irqsave(&priv->lock, flags);
        if (priv->outstanding_urbs > URB_UPPER_LIMIT * 2 / 3) {
                spin_unlock_irqrestore(&priv->lock, flags);
                dev_dbg(&port->dev, "%s - write limit hit\n", __func__);
                return 0;
        }
        spin_unlock_irqrestore(&priv->lock, flags);

        return 2048;
}

static unsigned int opticon_chars_in_buffer(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct opticon_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        unsigned int count;

        spin_lock_irqsave(&priv->lock, flags);
        count = priv->outstanding_bytes;
        spin_unlock_irqrestore(&priv->lock, flags);

        return count;
}

static int opticon_tiocmget(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct opticon_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        int result = 0;

        spin_lock_irqsave(&priv->lock, flags);
        if (priv->rts)
                result |= TIOCM_RTS;
        if (priv->cts)
                result |= TIOCM_CTS;
        spin_unlock_irqrestore(&priv->lock, flags);

        dev_dbg(&port->dev, "%s - %x\n", __func__, result);
        return result;
}

static int opticon_tiocmset(struct tty_struct *tty,
                           unsigned int set, unsigned int clear)
{
        struct usb_serial_port *port = tty->driver_data;
        struct opticon_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        bool rts;
        bool changed = false;
        int ret;

        /* We only support RTS so we only handle that */
        spin_lock_irqsave(&priv->lock, flags);

        rts = priv->rts;
        if (set & TIOCM_RTS)
                priv->rts = true;
        if (clear & TIOCM_RTS)
                priv->rts = false;
        changed = rts ^ priv->rts;
        spin_unlock_irqrestore(&priv->lock, flags);

        if (!changed)
                return 0;

        ret = send_control_msg(port, CONTROL_RTS, !rts);
        if (ret)
                return usb_translate_errors(ret);

        return 0;
}

static int opticon_port_probe(struct usb_serial_port *port)
{
        struct opticon_private *priv;

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        spin_lock_init(&priv->lock);
        init_usb_anchor(&priv->anchor);

        usb_set_serial_port_data(port, priv);

        return 0;
}

static void opticon_port_remove(struct usb_serial_port *port)
{
        struct opticon_private *priv = usb_get_serial_port_data(port);

        kfree(priv);
}

static struct usb_serial_driver opticon_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "opticon",
        },
        .id_table =             id_table,
        .num_ports =            1,
        .num_bulk_in =          1,
        .bulk_in_size =         256,
        .port_probe =           opticon_port_probe,
        .port_remove =          opticon_port_remove,
        .open =                 opticon_open,
        .close =                opticon_close,
        .write =                opticon_write,
        .write_room =           opticon_write_room,
        .chars_in_buffer =      opticon_chars_in_buffer,
        .throttle =             usb_serial_generic_throttle,
        .unthrottle =           usb_serial_generic_unthrottle,
        .tiocmget =             opticon_tiocmget,
        .tiocmset =             opticon_tiocmset,
        .process_read_urb =     opticon_process_read_urb,
};

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

module_usb_serial_driver(serial_drivers, id_table);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL v2");