// SPDX-License-Identifier: GPL-2.0+
/*
 * KLSI KL5KUSB105 chip RS232 converter driver
 *
 *   Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
 *   Copyright (C) 2001 Utz-Uwe Haus <haus@uuhaus.de>
 *
 * All information about the device was acquired using SniffUSB ans snoopUSB
 * on Windows98.
 * It was written out of frustration with the PalmConnect USB Serial adapter
 * sold by Palm Inc.
 * Neither Palm, nor their contractor (MCCI) or their supplier (KLSI) provided
 * information that was not already available.
 *
 * It seems that KLSI bought some silicon-design information from ScanLogic,
 * whose SL11R processor is at the core of the KL5KUSB chipset from KLSI.
 * KLSI has firmware available for their devices; it is probable that the
 * firmware differs from that used by KLSI in their products. If you have an
 * original KLSI device and can provide some information on it, I would be
 * most interested in adding support for it here. If you have any information
 * on the protocol used (or find errors in my reverse-engineered stuff), please
 * let me know.
 *
 * The code was only tested with a PalmConnect USB adapter; if you
 * are adventurous, try it with any KLSI-based device and let me know how it
 * breaks so that I can fix it!
 */

/* TODO:
 *      check modem line signals
 *      implement handshaking or decide that we do not support it
 */

#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/uaccess.h>
#include <asm/unaligned.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include "kl5kusb105.h"

#define DRIVER_AUTHOR "Utz-Uwe Haus <haus@uuhaus.de>, Johan Hovold <jhovold@gmail.com>"
#define DRIVER_DESC "KLSI KL5KUSB105 chipset USB->Serial Converter driver"


/*
 * Function prototypes
 */
static int klsi_105_port_probe(struct usb_serial_port *port);
static int klsi_105_port_remove(struct usb_serial_port *port);
static int  klsi_105_open(struct tty_struct *tty, struct usb_serial_port *port);
static void klsi_105_close(struct usb_serial_port *port);
static void klsi_105_set_termios(struct tty_struct *tty,
                        struct usb_serial_port *port, struct ktermios *old);
static int  klsi_105_tiocmget(struct tty_struct *tty);
static void klsi_105_process_read_urb(struct urb *urb);
static int klsi_105_prepare_write_buffer(struct usb_serial_port *port,
                                                void *dest, size_t size);

/*
 * All of the device info needed for the KLSI converters.
 */
static const struct usb_device_id id_table[] = {
        { USB_DEVICE(PALMCONNECT_VID, PALMCONNECT_PID) },
        { }             /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, id_table);

static struct usb_serial_driver kl5kusb105d_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "kl5kusb105d",
        },
        .description =          "KL5KUSB105D / PalmConnect",
        .id_table =             id_table,
        .num_ports =            1,
        .bulk_out_size =        64,
        .open =                 klsi_105_open,
        .close =                klsi_105_close,
        .set_termios =          klsi_105_set_termios,
        .tiocmget =             klsi_105_tiocmget,
        .port_probe =           klsi_105_port_probe,
        .port_remove =          klsi_105_port_remove,
        .throttle =             usb_serial_generic_throttle,
        .unthrottle =           usb_serial_generic_unthrottle,
        .process_read_urb =     klsi_105_process_read_urb,
        .prepare_write_buffer = klsi_105_prepare_write_buffer,
};

static struct usb_serial_driver * const serial_drivers[] = {
        &kl5kusb105d_device, NULL
};

struct klsi_105_port_settings {
        u8      pktlen;         /* always 5, it seems */
        u8      baudrate;
        u8      databits;
        u8      unknown1;
        u8      unknown2;
};

struct klsi_105_private {
        struct klsi_105_port_settings   cfg;
        unsigned long                   line_state; /* modem line settings */
        spinlock_t                      lock;
};


/*
 * Handle vendor specific USB requests
 */


#define KLSI_TIMEOUT     5000 /* default urb timeout */

static int klsi_105_chg_port_settings(struct usb_serial_port *port,
                                      struct klsi_105_port_settings *settings)
{
        int rc;

        rc = usb_control_msg(port->serial->dev,
                        usb_sndctrlpipe(port->serial->dev, 0),
                        KL5KUSB105A_SIO_SET_DATA,
                        USB_TYPE_VENDOR | USB_DIR_OUT | USB_RECIP_INTERFACE,
                        0, /* value */
                        0, /* index */
                        settings,
                        sizeof(struct klsi_105_port_settings),
                        KLSI_TIMEOUT);
        if (rc < 0)
                dev_err(&port->dev,
                        "Change port settings failed (error = %d)\n", rc);

        dev_dbg(&port->dev,
                "pktlen %u, baudrate 0x%02x, databits %u, u1 %u, u2 %u\n",
                settings->pktlen, settings->baudrate, settings->databits,
                settings->unknown1, settings->unknown2);

        return rc;
}

/* translate a 16-bit status value from the device to linux's TIO bits */
static unsigned long klsi_105_status2linestate(const __u16 status)
{
        unsigned long res = 0;

        res =   ((status & KL5KUSB105A_DSR) ? TIOCM_DSR : 0)
              | ((status & KL5KUSB105A_CTS) ? TIOCM_CTS : 0)
              ;

        return res;
}

/*
 * Read line control via vendor command and return result through
 * *line_state_p
 */
/* It seems that the status buffer has always only 2 bytes length */
#define KLSI_STATUSBUF_LEN      2
static int klsi_105_get_line_state(struct usb_serial_port *port,
                                   unsigned long *line_state_p)
{
        int rc;
        u8 *status_buf;
        __u16 status;

        status_buf = kmalloc(KLSI_STATUSBUF_LEN, GFP_KERNEL);
        if (!status_buf)
                return -ENOMEM;

        status_buf[0] = 0xff;
        status_buf[1] = 0xff;
        rc = usb_control_msg(port->serial->dev,
                             usb_rcvctrlpipe(port->serial->dev, 0),
                             KL5KUSB105A_SIO_POLL,
                             USB_TYPE_VENDOR | USB_DIR_IN,
                             0, /* value */
                             0, /* index */
                             status_buf, KLSI_STATUSBUF_LEN,
                             10000
                             );
        if (rc != KLSI_STATUSBUF_LEN) {
                dev_err(&port->dev, "reading line status failed: %d\n", rc);
                if (rc >= 0)
                        rc = -EIO;
        } else {
                status = get_unaligned_le16(status_buf);

                dev_dbg(&port->dev, "read status %02x %02x\n",
                        status_buf[0], status_buf[1]);

                *line_state_p = klsi_105_status2linestate(status);
        }

        kfree(status_buf);
        return rc;
}


/*
 * Driver's tty interface functions
 */

static int klsi_105_port_probe(struct usb_serial_port *port)
{
        struct klsi_105_private *priv;

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

        /* set initial values for control structures */
        priv->cfg.pktlen    = 5;
        priv->cfg.baudrate  = kl5kusb105a_sio_b9600;
        priv->cfg.databits  = kl5kusb105a_dtb_8;
        priv->cfg.unknown1  = 0;
        priv->cfg.unknown2  = 1;

        priv->line_state    = 0;

        spin_lock_init(&priv->lock);

        usb_set_serial_port_data(port, priv);

        return 0;
}

static int klsi_105_port_remove(struct usb_serial_port *port)
{
        struct klsi_105_private *priv;

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

        return 0;
}

static int  klsi_105_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct klsi_105_private *priv = usb_get_serial_port_data(port);
        int retval = 0;
        int rc;
        unsigned long line_state;
        struct klsi_105_port_settings *cfg;
        unsigned long flags;

        /* Do a defined restart:
         * Set up sane default baud rate and send the 'READ_ON'
         * vendor command.
         * FIXME: set modem line control (how?)
         * Then read the modem line control and store values in
         * priv->line_state.
         */
        cfg = kmalloc(sizeof(*cfg), GFP_KERNEL);
        if (!cfg)
                return -ENOMEM;

        cfg->pktlen   = 5;
        cfg->baudrate = kl5kusb105a_sio_b9600;
        cfg->databits = kl5kusb105a_dtb_8;
        cfg->unknown1 = 0;
        cfg->unknown2 = 1;
        klsi_105_chg_port_settings(port, cfg);

        spin_lock_irqsave(&priv->lock, flags);
        priv->cfg.pktlen   = cfg->pktlen;
        priv->cfg.baudrate = cfg->baudrate;
        priv->cfg.databits = cfg->databits;
        priv->cfg.unknown1 = cfg->unknown1;
        priv->cfg.unknown2 = cfg->unknown2;
        spin_unlock_irqrestore(&priv->lock, flags);

        /* READ_ON and urb submission */
        rc = usb_serial_generic_open(tty, port);
        if (rc) {
                retval = rc;
                goto err_free_cfg;
        }

        rc = usb_control_msg(port->serial->dev,
                             usb_sndctrlpipe(port->serial->dev, 0),
                             KL5KUSB105A_SIO_CONFIGURE,
                             USB_TYPE_VENDOR|USB_DIR_OUT|USB_RECIP_INTERFACE,
                             KL5KUSB105A_SIO_CONFIGURE_READ_ON,
                             0, /* index */
                             NULL,
                             0,
                             KLSI_TIMEOUT);
        if (rc < 0) {
                dev_err(&port->dev, "Enabling read failed (error = %d)\n", rc);
                retval = rc;
                goto err_generic_close;
        } else
                dev_dbg(&port->dev, "%s - enabled reading\n", __func__);

        rc = klsi_105_get_line_state(port, &line_state);
        if (rc < 0) {
                retval = rc;
                goto err_disable_read;
        }

        spin_lock_irqsave(&priv->lock, flags);
        priv->line_state = line_state;
        spin_unlock_irqrestore(&priv->lock, flags);
        dev_dbg(&port->dev, "%s - read line state 0x%lx\n", __func__,
                        line_state);

        return 0;

err_disable_read:
        usb_control_msg(port->serial->dev,
                             usb_sndctrlpipe(port->serial->dev, 0),
                             KL5KUSB105A_SIO_CONFIGURE,
                             USB_TYPE_VENDOR | USB_DIR_OUT,
                             KL5KUSB105A_SIO_CONFIGURE_READ_OFF,
                             0, /* index */
                             NULL, 0,
                             KLSI_TIMEOUT);
err_generic_close:
        usb_serial_generic_close(port);
err_free_cfg:
        kfree(cfg);

        return retval;
}

static void klsi_105_close(struct usb_serial_port *port)
{
        int rc;

        /* send READ_OFF */
        rc = usb_control_msg(port->serial->dev,
                             usb_sndctrlpipe(port->serial->dev, 0),
                             KL5KUSB105A_SIO_CONFIGURE,
                             USB_TYPE_VENDOR | USB_DIR_OUT,
                             KL5KUSB105A_SIO_CONFIGURE_READ_OFF,
                             0, /* index */
                             NULL, 0,
                             KLSI_TIMEOUT);
        if (rc < 0)
                dev_err(&port->dev, "failed to disable read: %d\n", rc);

        /* shutdown our bulk reads and writes */
        usb_serial_generic_close(port);
}

/* We need to write a complete 64-byte data block and encode the
 * number actually sent in the first double-byte, LSB-order. That
 * leaves at most 62 bytes of payload.
 */
#define KLSI_HDR_LEN            2
static int klsi_105_prepare_write_buffer(struct usb_serial_port *port,
                                                void *dest, size_t size)
{
        unsigned char *buf = dest;
        int count;

        count = kfifo_out_locked(&port->write_fifo, buf + KLSI_HDR_LEN, size,
                                                                &port->lock);
        put_unaligned_le16(count, buf);

        return count + KLSI_HDR_LEN;
}

/* The data received is preceded by a length double-byte in LSB-first order.
 */
static void klsi_105_process_read_urb(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        unsigned char *data = urb->transfer_buffer;
        unsigned len;

        /* empty urbs seem to happen, we ignore them */
        if (!urb->actual_length)
                return;

        if (urb->actual_length <= KLSI_HDR_LEN) {
                dev_dbg(&port->dev, "%s - malformed packet\n", __func__);
                return;
        }

        len = get_unaligned_le16(data);
        if (len > urb->actual_length - KLSI_HDR_LEN) {
                dev_dbg(&port->dev, "%s - packet length mismatch\n", __func__);
                len = urb->actual_length - KLSI_HDR_LEN;
        }

        tty_insert_flip_string(&port->port, data + KLSI_HDR_LEN, len);
        tty_flip_buffer_push(&port->port);
}

static void klsi_105_set_termios(struct tty_struct *tty,
                                 struct usb_serial_port *port,
                                 struct ktermios *old_termios)
{
        struct klsi_105_private *priv = usb_get_serial_port_data(port);
        struct device *dev = &port->dev;
        unsigned int iflag = tty->termios.c_iflag;
        unsigned int old_iflag = old_termios->c_iflag;
        unsigned int cflag = tty->termios.c_cflag;
        unsigned int old_cflag = old_termios->c_cflag;
        struct klsi_105_port_settings *cfg;
        unsigned long flags;
        speed_t baud;

        cfg = kmalloc(sizeof(*cfg), GFP_KERNEL);
        if (!cfg)
                return;

        /* lock while we are modifying the settings */
        spin_lock_irqsave(&priv->lock, flags);

        /*
         * Update baud rate
         */
        baud = tty_get_baud_rate(tty);

        switch (baud) {
        case 0: /* handled below */
                break;
        case 1200:
                priv->cfg.baudrate = kl5kusb105a_sio_b1200;
                break;
        case 2400:
                priv->cfg.baudrate = kl5kusb105a_sio_b2400;
                break;
        case 4800:
                priv->cfg.baudrate = kl5kusb105a_sio_b4800;
                break;
        case 9600:
                priv->cfg.baudrate = kl5kusb105a_sio_b9600;
                break;
        case 19200:
                priv->cfg.baudrate = kl5kusb105a_sio_b19200;
                break;
        case 38400:
                priv->cfg.baudrate = kl5kusb105a_sio_b38400;
                break;
        case 57600:
                priv->cfg.baudrate = kl5kusb105a_sio_b57600;
                break;
        case 115200:
                priv->cfg.baudrate = kl5kusb105a_sio_b115200;
                break;
        default:
                dev_dbg(dev, "unsupported baudrate, using 9600\n");
                priv->cfg.baudrate = kl5kusb105a_sio_b9600;
                baud = 9600;
                break;
        }

        /*
         * FIXME: implement B0 handling
         *
         * Maybe this should be simulated by sending read disable and read
         * enable messages?
         */

        tty_encode_baud_rate(tty, baud, baud);

        if ((cflag & CSIZE) != (old_cflag & CSIZE)) {
                /* set the number of data bits */
                switch (cflag & CSIZE) {
                case CS5:
                        dev_dbg(dev, "%s - 5 bits/byte not supported\n", __func__);
                        spin_unlock_irqrestore(&priv->lock, flags);
                        goto err;
                case CS6:
                        dev_dbg(dev, "%s - 6 bits/byte not supported\n", __func__);
                        spin_unlock_irqrestore(&priv->lock, flags);
                        goto err;
                case CS7:
                        priv->cfg.databits = kl5kusb105a_dtb_7;
                        break;
                case CS8:
                        priv->cfg.databits = kl5kusb105a_dtb_8;
                        break;
                default:
                        dev_err(dev, "CSIZE was not CS5-CS8, using default of 8\n");
                        priv->cfg.databits = kl5kusb105a_dtb_8;
                        break;
                }
        }

        /*
         * Update line control register (LCR)
         */
        if ((cflag & (PARENB|PARODD)) != (old_cflag & (PARENB|PARODD))
            || (cflag & CSTOPB) != (old_cflag & CSTOPB)) {
                /* Not currently supported */
                tty->termios.c_cflag &= ~(PARENB|PARODD|CSTOPB);
        }
        /*
         * Set flow control: well, I do not really now how to handle DTR/RTS.
         * Just do what we have seen with SniffUSB on Win98.
         */
        if ((iflag & IXOFF) != (old_iflag & IXOFF)
            || (iflag & IXON) != (old_iflag & IXON)
            ||  (cflag & CRTSCTS) != (old_cflag & CRTSCTS)) {
                /* Not currently supported */
                tty->termios.c_cflag &= ~CRTSCTS;
        }
        memcpy(cfg, &priv->cfg, sizeof(*cfg));
        spin_unlock_irqrestore(&priv->lock, flags);

        /* now commit changes to device */
        klsi_105_chg_port_settings(port, cfg);
err:
        kfree(cfg);
}

static int klsi_105_tiocmget(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct klsi_105_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        int rc;
        unsigned long line_state;

        rc = klsi_105_get_line_state(port, &line_state);
        if (rc < 0) {
                dev_err(&port->dev,
                        "Reading line control failed (error = %d)\n", rc);
                /* better return value? EAGAIN? */
                return rc;
        }

        spin_lock_irqsave(&priv->lock, flags);
        priv->line_state = line_state;
        spin_unlock_irqrestore(&priv->lock, flags);
        dev_dbg(&port->dev, "%s - read line state 0x%lx\n", __func__, line_state);
        return (int)line_state;
}

module_usb_serial_driver(serial_drivers, id_table);

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