drivers/usb/serial/sam-ba.c

   1 /*
   2  * Atmel SAM Boot Assistant (SAM-BA) driver
   3  *
   4  * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License version
   8  *      2 as published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/tty.h>
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/usb.h>
  16 #include <linux/usb/serial.h>
  17
  18
  19 #define DRIVER_VERSION  "v1.0"
  20 #define DRIVER_AUTHOR   "Johan Hovold <jhovold@gmail.com>"
  21 #define DRIVER_DESC     "Atmel SAM Boot Assistant (SAM-BA) driver"
  22
  23 #define SAMBA_VENDOR_ID         0x3eb
  24 #define SAMBA_PRODUCT_ID        0x6124
  25
  26
  27 static int debug;
  28
  29 static const struct usb_device_id id_table[] = {
  30         /*
  31          * NOTE: Only match the CDC Data interface.
  32          */
  33         { USB_DEVICE_AND_INTERFACE_INFO(SAMBA_VENDOR_ID, SAMBA_PRODUCT_ID,
  34                                         USB_CLASS_CDC_DATA, 0, 0) },
  35         { }
  36 };
  37 MODULE_DEVICE_TABLE(usb, id_table);
  38
  39 static struct usb_driver samba_driver = {
  40         .name           = "sam-ba",
  41         .probe          = usb_serial_probe,
  42         .disconnect     = usb_serial_disconnect,
  43         .id_table       = id_table,
  44         .no_dynamic_id  = 1,
  45 };
  46
  47
  48 /*
  49  * NOTE: The SAM-BA firmware cannot handle merged write requests so we cannot
  50  *       use the generic write implementation (which uses the port write fifo).
  51  */
  52 static int samba_write(struct tty_struct *tty, struct usb_serial_port *port,
  53                                         const unsigned char *buf, int count)
  54 {
  55         struct urb *urb;
  56         unsigned long flags;
  57         int result;
  58         int i;
  59
  60         if (!count)
  61                 return 0;
  62
  63         count = min_t(int, count, port->bulk_out_size);
  64
  65         spin_lock_irqsave(&port->lock, flags);
  66         if (!port->write_urbs_free) {
  67                 spin_unlock_irqrestore(&port->lock, flags);
  68                 return 0;
  69         }
  70         i = find_first_bit(&port->write_urbs_free,
  71                                                 ARRAY_SIZE(port->write_urbs));
  72         __clear_bit(i, &port->write_urbs_free);
  73         port->tx_bytes += count;
  74         spin_unlock_irqrestore(&port->lock, flags);
  75
  76         urb = port->write_urbs[i];
  77         memcpy(urb->transfer_buffer, buf, count);
  78         urb->transfer_buffer_length = count;
  79         usb_serial_debug_data(debug, &port->dev, __func__, count,
  80                                                 urb->transfer_buffer);
  81         result = usb_submit_urb(urb, GFP_ATOMIC);
  82         if (result) {
  83                 dev_err(&port->dev, "%s - error submitting urb: %d\n",
  84                                                 __func__, result);
  85                 spin_lock_irqsave(&port->lock, flags);
  86                 __set_bit(i, &port->write_urbs_free);
  87                 port->tx_bytes -= count;
  88                 spin_unlock_irqrestore(&port->lock, flags);
  89
  90                 return result;
  91         }
  92
  93         return count;
  94 }
  95
  96 static int samba_write_room(struct tty_struct *tty)
  97 {
  98         struct usb_serial_port *port = tty->driver_data;
  99         unsigned long flags;
 100         unsigned long free;
 101         int count;
 102         int room;
 103
 104         spin_lock_irqsave(&port->lock, flags);
 105         free = port->write_urbs_free;
 106         spin_unlock_irqrestore(&port->lock, flags);
 107
 108         count = hweight_long(free);
 109         room = count * port->bulk_out_size;
 110
 111         dbg("%s - returns %d", __func__, room);
 112
 113         return room;
 114 }
 115
 116 static int samba_chars_in_buffer(struct tty_struct *tty)
 117 {
 118         struct usb_serial_port *port = tty->driver_data;
 119         unsigned long flags;
 120         int chars;
 121
 122         spin_lock_irqsave(&port->lock, flags);
 123         chars = port->tx_bytes;
 124         spin_unlock_irqrestore(&port->lock, flags);
 125
 126         dbg("%s - returns %d", __func__, chars);
 127
 128         return chars;
 129 }
 130
 131 static void samba_write_bulk_callback(struct urb *urb)
 132 {
 133         struct usb_serial_port *port = urb->context;
 134         unsigned long flags;
 135         int i;
 136
 137         dbg("%s - port %d", __func__, port->number);
 138
 139         for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) {
 140                 if (port->write_urbs[i] == urb)
 141                         break;
 142         }
 143         spin_lock_irqsave(&port->lock, flags);
 144         __set_bit(i, &port->write_urbs_free);
 145         port->tx_bytes -= urb->transfer_buffer_length;
 146         spin_unlock_irqrestore(&port->lock, flags);
 147
 148         if (urb->status)
 149                 dbg("%s - non-zero urb status: %d", __func__, urb->status);
 150
 151         usb_serial_port_softint(port);
 152 }
 153
 154 static struct usb_serial_driver samba_device = {
 155         .driver = {
 156                 .owner          = THIS_MODULE,
 157                 .name           = "sam-ba",
 158         },
 159         .usb_driver             = &samba_driver,
 160         .id_table               = id_table,
 161         .num_ports              = 1,
 162         .bulk_in_size           = 512,
 163         .bulk_out_size          = 2048,
 164         .write                  = samba_write,
 165         .write_room             = samba_write_room,
 166         .chars_in_buffer        = samba_chars_in_buffer,
 167         .write_bulk_callback    = samba_write_bulk_callback,
 168         .throttle               = usb_serial_generic_throttle,
 169         .unthrottle             = usb_serial_generic_unthrottle,
 170 };
 171
 172 static int __init samba_init(void)
 173 {
 174         int retval;
 175
 176         retval = usb_serial_register(&samba_device);
 177         if (retval)
 178                 return retval;
 179
 180         retval = usb_register(&samba_driver);
 181         if (retval) {
 182                 usb_serial_deregister(&samba_device);
 183                 return retval;
 184         }
 185
 186         printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ": "
 187                                                         DRIVER_DESC "\n");
 188         return 0;
 189 }
 190
 191 static void __exit samba_exit(void)
 192 {
 193         usb_deregister(&samba_driver);
 194         usb_serial_deregister(&samba_device);
 195 }
 196
 197 module_init(samba_init);
 198 module_exit(samba_exit);
 199
 200 MODULE_AUTHOR(DRIVER_AUTHOR);
 201 MODULE_DESCRIPTION(DRIVER_DESC);
 202 MODULE_VERSION(DRIVER_VERSION);
 203 MODULE_LICENSE("GPL");
 204
 205 module_param(debug, bool, S_IRUGO | S_IWUSR);
 206 MODULE_PARM_DESC(debug, "Enable verbose debugging messages");