drivers/usb/serial/symbolserial.c

   1 /*
   2  * Symbol USB barcode to serial driver
   3  *
   4  * Copyright (C) 2013 Johan Hovold <jhovold@gmail.com>
   5  * Copyright (C) 2009 Greg Kroah-Hartman <gregkh@suse.de>
   6  * Copyright (C) 2009 Novell Inc.
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of the GNU General Public License version
  10  *      2 as published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/tty.h>
  15 #include <linux/slab.h>
  16 #include <linux/tty_driver.h>
  17 #include <linux/tty_flip.h>
  18 #include <linux/module.h>
  19 #include <linux/usb.h>
  20 #include <linux/usb/serial.h>
  21 #include <linux/uaccess.h>
  22
  23 static const struct usb_device_id id_table[] = {
  24         { USB_DEVICE(0x05e0, 0x0600) },
  25         { },
  26 };
  27 MODULE_DEVICE_TABLE(usb, id_table);
  28
  29 struct symbol_private {
  30         spinlock_t lock;        /* protects the following flags */
  31         bool throttled;
  32         bool actually_throttled;
  33 };
  34
  35 static void symbol_int_callback(struct urb *urb)
  36 {
  37         struct usb_serial_port *port = urb->context;
  38         struct symbol_private *priv = usb_get_serial_port_data(port);
  39         unsigned char *data = urb->transfer_buffer;
  40         int status = urb->status;
  41         int result;
  42         int data_length;
  43
  44         switch (status) {
  45         case 0:
  46                 /* success */
  47                 break;
  48         case -ECONNRESET:
  49         case -ENOENT:
  50         case -ESHUTDOWN:
  51                 /* this urb is terminated, clean up */
  52                 dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n",
  53                         __func__, status);
  54                 return;
  55         default:
  56                 dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n",
  57                         __func__, status);
  58                 goto exit;
  59         }
  60
  61         usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
  62
  63         if (urb->actual_length > 1) {
  64                 data_length = urb->actual_length - 1;
  65
  66                 /*
  67                  * Data from the device comes with a 1 byte header:
  68                  *
  69                  * <size of data>data...
  70                  *      This is real data to be sent to the tty layer
  71                  * we pretty much just ignore the size and send everything
  72                  * else to the tty layer.
  73                  */
  74                 tty_insert_flip_string(&port->port, &data[1], data_length);
  75                 tty_flip_buffer_push(&port->port);
  76         } else {
  77                 dev_dbg(&port->dev,
  78                         "Improper amount of data received from the device, "
  79                         "%d bytes", urb->actual_length);
  80         }
  81
  82 exit:
  83         spin_lock(&priv->lock);
  84
  85         /* Continue trying to always read if we should */
  86         if (!priv->throttled) {
  87                 result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
  88                 if (result)
  89                         dev_err(&port->dev,
  90                             "%s - failed resubmitting read urb, error %d\n",
  91                                                         __func__, result);
  92         } else
  93                 priv->actually_throttled = true;
  94         spin_unlock(&priv->lock);
  95 }
  96
  97 static int symbol_open(struct tty_struct *tty, struct usb_serial_port *port)
  98 {
  99         struct symbol_private *priv = usb_get_serial_data(port->serial);
 100         unsigned long flags;
 101         int result = 0;
 102
 103         spin_lock_irqsave(&priv->lock, flags);
 104         priv->throttled = false;
 105         priv->actually_throttled = false;
 106         spin_unlock_irqrestore(&priv->lock, flags);
 107
 108         /* Start reading from the device */
 109         result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 110         if (result)
 111                 dev_err(&port->dev,
 112                         "%s - failed resubmitting read urb, error %d\n",
 113                         __func__, result);
 114         return result;
 115 }
 116
 117 static void symbol_close(struct usb_serial_port *port)
 118 {
 119         usb_kill_urb(port->interrupt_in_urb);
 120 }
 121
 122 static void symbol_throttle(struct tty_struct *tty)
 123 {
 124         struct usb_serial_port *port = tty->driver_data;
 125         struct symbol_private *priv = usb_get_serial_data(port->serial);
 126
 127         spin_lock_irq(&priv->lock);
 128         priv->throttled = true;
 129         spin_unlock_irq(&priv->lock);
 130 }
 131
 132 static void symbol_unthrottle(struct tty_struct *tty)
 133 {
 134         struct usb_serial_port *port = tty->driver_data;
 135         struct symbol_private *priv = usb_get_serial_data(port->serial);
 136         int result;
 137         bool was_throttled;
 138
 139         spin_lock_irq(&priv->lock);
 140         priv->throttled = false;
 141         was_throttled = priv->actually_throttled;
 142         priv->actually_throttled = false;
 143         spin_unlock_irq(&priv->lock);
 144
 145         if (was_throttled) {
 146                 result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 147                 if (result)
 148                         dev_err(&port->dev,
 149                                 "%s - failed submitting read urb, error %d\n",
 150                                                         __func__, result);
 151         }
 152 }
 153
 154 static int symbol_startup(struct usb_serial *serial)
 155 {
 156         if (!serial->num_interrupt_in) {
 157                 dev_err(&serial->dev->dev, "no interrupt-in endpoint\n");
 158                 return -ENODEV;
 159         }
 160
 161         return 0;
 162 }
 163
 164 static int symbol_port_probe(struct usb_serial_port *port)
 165 {
 166         struct symbol_private *priv;
 167
 168         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 169         if (!priv)
 170                 return -ENOMEM;
 171
 172         spin_lock_init(&priv->lock);
 173
 174         usb_set_serial_port_data(port, priv);
 175
 176         return 0;
 177 }
 178
 179 static int symbol_port_remove(struct usb_serial_port *port)
 180 {
 181         struct symbol_private *priv = usb_get_serial_port_data(port);
 182
 183         kfree(priv);
 184
 185         return 0;
 186 }
 187
 188 static struct usb_serial_driver symbol_device = {
 189         .driver = {
 190                 .owner =        THIS_MODULE,
 191                 .name =         "symbol",
 192         },
 193         .id_table =             id_table,
 194         .num_ports =            1,
 195         .attach =               symbol_startup,
 196         .port_probe =           symbol_port_probe,
 197         .port_remove =          symbol_port_remove,
 198         .open =                 symbol_open,
 199         .close =                symbol_close,
 200         .throttle =             symbol_throttle,
 201         .unthrottle =           symbol_unthrottle,
 202         .read_int_callback =    symbol_int_callback,
 203 };
 204
 205 static struct usb_serial_driver * const serial_drivers[] = {
 206         &symbol_device, NULL
 207 };
 208
 209 module_usb_serial_driver(serial_drivers, id_table);
 210
 211 MODULE_LICENSE("GPL");