drivers/usb/misc/usblcd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*****************************************************************************
   3  *                          USBLCD Kernel Driver                             *
   4  *                            Version 1.05                                   *
   5  *             (C) 2005 Georges Toth <g.toth@e-biz.lu>                       *
   6  *                                                                           *
   7  *     This file is licensed under the GPL. See COPYING in the package.      *
   8  * Based on usb-skeleton.c 2.0 by Greg Kroah-Hartman (greg@kroah.com)        *
   9  *                                                                           *
  10  *                                                                           *
  11  * 28.02.05 Complete rewrite of the original usblcd.c driver,                *
  12  *          based on usb_skeleton.c.                                         *
  13  *          This new driver allows more than one USB-LCD to be connected     *
  14  *          and controlled, at once                                          *
  15  *****************************************************************************/
  16 #include <linux/module.h>
  17 #include <linux/kernel.h>
  18 #include <linux/slab.h>
  19 #include <linux/errno.h>
  20 #include <linux/mutex.h>
  21 #include <linux/rwsem.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/usb.h>
  24
  25 #define DRIVER_VERSION "USBLCD Driver Version 1.05"
  26
  27 #define USBLCD_MINOR            144
  28
  29 #define IOCTL_GET_HARD_VERSION  1
  30 #define IOCTL_GET_DRV_VERSION   2
  31
  32
  33 static const struct usb_device_id id_table[] = {
  34         { .idVendor = 0x10D2, .match_flags = USB_DEVICE_ID_MATCH_VENDOR, },
  35         { },
  36 };
  37 MODULE_DEVICE_TABLE(usb, id_table);
  38
  39 struct usb_lcd {
  40         struct usb_device       *udev;                  /* init: probe_lcd */
  41         struct usb_interface    *interface;             /* the interface for
  42                                                            this device */
  43         unsigned char           *bulk_in_buffer;        /* the buffer to receive
  44                                                            data */
  45         size_t                  bulk_in_size;           /* the size of the
  46                                                            receive buffer */
  47         __u8                    bulk_in_endpointAddr;   /* the address of the
  48                                                            bulk in endpoint */
  49         __u8                    bulk_out_endpointAddr;  /* the address of the
  50                                                            bulk out endpoint */
  51         struct kref             kref;
  52         struct semaphore        limit_sem;              /* to stop writes at
  53                                                            full throttle from
  54                                                            using up all RAM */
  55         struct usb_anchor       submitted;              /* URBs to wait for
  56                                                            before suspend */
  57         struct rw_semaphore     io_rwsem;
  58         unsigned long           disconnected:1;
  59 };
  60 #define to_lcd_dev(d) container_of(d, struct usb_lcd, kref)
  61
  62 #define USB_LCD_CONCURRENT_WRITES       5
  63
  64 static struct usb_driver lcd_driver;
  65
  66
  67 static void lcd_delete(struct kref *kref)
  68 {
  69         struct usb_lcd *dev = to_lcd_dev(kref);
  70
  71         usb_put_dev(dev->udev);
  72         kfree(dev->bulk_in_buffer);
  73         kfree(dev);
  74 }
  75
  76
  77 static int lcd_open(struct inode *inode, struct file *file)
  78 {
  79         struct usb_lcd *dev;
  80         struct usb_interface *interface;
  81         int subminor, r;
  82
  83         subminor = iminor(inode);
  84
  85         interface = usb_find_interface(&lcd_driver, subminor);
  86         if (!interface) {
  87                 pr_err("USBLCD: %s - error, can't find device for minor %d\n",
  88                        __func__, subminor);
  89                 return -ENODEV;
  90         }
  91
  92         dev = usb_get_intfdata(interface);
  93
  94         /* increment our usage count for the device */
  95         kref_get(&dev->kref);
  96
  97         /* grab a power reference */
  98         r = usb_autopm_get_interface(interface);
  99         if (r < 0) {
 100                 kref_put(&dev->kref, lcd_delete);
 101                 return r;
 102         }
 103
 104         /* save our object in the file's private structure */
 105         file->private_data = dev;
 106
 107         return 0;
 108 }
 109
 110 static int lcd_release(struct inode *inode, struct file *file)
 111 {
 112         struct usb_lcd *dev;
 113
 114         dev = file->private_data;
 115         if (dev == NULL)
 116                 return -ENODEV;
 117
 118         /* decrement the count on our device */
 119         usb_autopm_put_interface(dev->interface);
 120         kref_put(&dev->kref, lcd_delete);
 121         return 0;
 122 }
 123
 124 static ssize_t lcd_read(struct file *file, char __user * buffer,
 125                         size_t count, loff_t *ppos)
 126 {
 127         struct usb_lcd *dev;
 128         int retval = 0;
 129         int bytes_read;
 130
 131         dev = file->private_data;
 132
 133         down_read(&dev->io_rwsem);
 134
 135         if (dev->disconnected) {
 136                 retval = -ENODEV;
 137                 goto out_up_io;
 138         }
 139
 140         /* do a blocking bulk read to get data from the device */
 141         retval = usb_bulk_msg(dev->udev,
 142                               usb_rcvbulkpipe(dev->udev,
 143                                               dev->bulk_in_endpointAddr),
 144                               dev->bulk_in_buffer,
 145                               min(dev->bulk_in_size, count),
 146                               &bytes_read, 10000);
 147
 148         /* if the read was successful, copy the data to userspace */
 149         if (!retval) {
 150                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 151                         retval = -EFAULT;
 152                 else
 153                         retval = bytes_read;
 154         }
 155
 156 out_up_io:
 157         up_read(&dev->io_rwsem);
 158
 159         return retval;
 160 }
 161
 162 static long lcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 163 {
 164         struct usb_lcd *dev;
 165         u16 bcdDevice;
 166         char buf[30];
 167
 168         dev = file->private_data;
 169         if (dev == NULL)
 170                 return -ENODEV;
 171
 172         switch (cmd) {
 173         case IOCTL_GET_HARD_VERSION:
 174                 bcdDevice = le16_to_cpu((dev->udev)->descriptor.bcdDevice);
 175                 sprintf(buf, "%1d%1d.%1d%1d",
 176                         (bcdDevice & 0xF000)>>12,
 177                         (bcdDevice & 0xF00)>>8,
 178                         (bcdDevice & 0xF0)>>4,
 179                         (bcdDevice & 0xF));
 180                 if (copy_to_user((void __user *)arg, buf, strlen(buf)) != 0)
 181                         return -EFAULT;
 182                 break;
 183         case IOCTL_GET_DRV_VERSION:
 184                 sprintf(buf, DRIVER_VERSION);
 185                 if (copy_to_user((void __user *)arg, buf, strlen(buf)) != 0)
 186                         return -EFAULT;
 187                 break;
 188         default:
 189                 return -ENOTTY;
 190         }
 191
 192         return 0;
 193 }
 194
 195 static void lcd_write_bulk_callback(struct urb *urb)
 196 {
 197         struct usb_lcd *dev;
 198         int status = urb->status;
 199
 200         dev = urb->context;
 201
 202         /* sync/async unlink faults aren't errors */
 203         if (status &&
 204             !(status == -ENOENT ||
 205               status == -ECONNRESET ||
 206               status == -ESHUTDOWN)) {
 207                 dev_dbg(&dev->interface->dev,
 208                         "nonzero write bulk status received: %d\n", status);
 209         }
 210
 211         /* free up our allocated buffer */
 212         usb_free_coherent(urb->dev, urb->transfer_buffer_length,
 213                           urb->transfer_buffer, urb->transfer_dma);
 214         up(&dev->limit_sem);
 215 }
 216
 217 static ssize_t lcd_write(struct file *file, const char __user * user_buffer,
 218                          size_t count, loff_t *ppos)
 219 {
 220         struct usb_lcd *dev;
 221         int retval = 0, r;
 222         struct urb *urb = NULL;
 223         char *buf = NULL;
 224
 225         dev = file->private_data;
 226
 227         /* verify that we actually have some data to write */
 228         if (count == 0)
 229                 goto exit;
 230
 231         r = down_interruptible(&dev->limit_sem);
 232         if (r < 0)
 233                 return -EINTR;
 234
 235         down_read(&dev->io_rwsem);
 236
 237         if (dev->disconnected) {
 238                 retval = -ENODEV;
 239                 goto err_up_io;
 240         }
 241
 242         /* create a urb, and a buffer for it, and copy the data to the urb */
 243         urb = usb_alloc_urb(0, GFP_KERNEL);
 244         if (!urb) {
 245                 retval = -ENOMEM;
 246                 goto err_up_io;
 247         }
 248
 249         buf = usb_alloc_coherent(dev->udev, count, GFP_KERNEL,
 250                                  &urb->transfer_dma);
 251         if (!buf) {
 252                 retval = -ENOMEM;
 253                 goto error;
 254         }
 255
 256         if (copy_from_user(buf, user_buffer, count)) {
 257                 retval = -EFAULT;
 258                 goto error;
 259         }
 260
 261         /* initialize the urb properly */
 262         usb_fill_bulk_urb(urb, dev->udev,
 263                           usb_sndbulkpipe(dev->udev,
 264                           dev->bulk_out_endpointAddr),
 265                           buf, count, lcd_write_bulk_callback, dev);
 266         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 267
 268         usb_anchor_urb(urb, &dev->submitted);
 269
 270         /* send the data out the bulk port */
 271         retval = usb_submit_urb(urb, GFP_KERNEL);
 272         if (retval) {
 273                 dev_err(&dev->udev->dev,
 274                         "%s - failed submitting write urb, error %d\n",
 275                         __func__, retval);
 276                 goto error_unanchor;
 277         }
 278
 279         /* release our reference to this urb,
 280            the USB core will eventually free it entirely */
 281         usb_free_urb(urb);
 282
 283         up_read(&dev->io_rwsem);
 284 exit:
 285         return count;
 286 error_unanchor:
 287         usb_unanchor_urb(urb);
 288 error:
 289         usb_free_coherent(dev->udev, count, buf, urb->transfer_dma);
 290         usb_free_urb(urb);
 291 err_up_io:
 292         up_read(&dev->io_rwsem);
 293         up(&dev->limit_sem);
 294         return retval;
 295 }
 296
 297 static const struct file_operations lcd_fops = {
 298         .owner =        THIS_MODULE,
 299         .read =         lcd_read,
 300         .write =        lcd_write,
 301         .open =         lcd_open,
 302         .unlocked_ioctl = lcd_ioctl,
 303         .release =      lcd_release,
 304         .llseek =        noop_llseek,
 305 };
 306
 307 /*
 308  * usb class driver info in order to get a minor number from the usb core,
 309  * and to have the device registered with the driver core
 310  */
 311 static struct usb_class_driver lcd_class = {
 312         .name =         "lcd%d",
 313         .fops =         &lcd_fops,
 314         .minor_base =   USBLCD_MINOR,
 315 };
 316
 317 static int lcd_probe(struct usb_interface *interface,
 318                      const struct usb_device_id *id)
 319 {
 320         struct usb_lcd *dev = NULL;
 321         struct usb_endpoint_descriptor *bulk_in, *bulk_out;
 322         int i;
 323         int retval;
 324
 325         /* allocate memory for our device state and initialize it */
 326         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 327         if (!dev)
 328                 return -ENOMEM;
 329
 330         kref_init(&dev->kref);
 331         sema_init(&dev->limit_sem, USB_LCD_CONCURRENT_WRITES);
 332         init_rwsem(&dev->io_rwsem);
 333         init_usb_anchor(&dev->submitted);
 334
 335         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 336         dev->interface = interface;
 337
 338         if (le16_to_cpu(dev->udev->descriptor.idProduct) != 0x0001) {
 339                 dev_warn(&interface->dev, "USBLCD model not supported.\n");
 340                 retval = -ENODEV;
 341                 goto error;
 342         }
 343
 344         /* set up the endpoint information */
 345         /* use only the first bulk-in and bulk-out endpoints */
 346         retval = usb_find_common_endpoints(interface->cur_altsetting,
 347                         &bulk_in, &bulk_out, NULL, NULL);
 348         if (retval) {
 349                 dev_err(&interface->dev,
 350                         "Could not find both bulk-in and bulk-out endpoints\n");
 351                 goto error;
 352         }
 353
 354         dev->bulk_in_size = usb_endpoint_maxp(bulk_in);
 355         dev->bulk_in_endpointAddr = bulk_in->bEndpointAddress;
 356         dev->bulk_in_buffer = kmalloc(dev->bulk_in_size, GFP_KERNEL);
 357         if (!dev->bulk_in_buffer) {
 358                 retval = -ENOMEM;
 359                 goto error;
 360         }
 361
 362         dev->bulk_out_endpointAddr = bulk_out->bEndpointAddress;
 363
 364         /* save our data pointer in this interface device */
 365         usb_set_intfdata(interface, dev);
 366
 367         /* we can register the device now, as it is ready */
 368         retval = usb_register_dev(interface, &lcd_class);
 369         if (retval) {
 370                 /* something prevented us from registering this driver */
 371                 dev_err(&interface->dev,
 372                         "Not able to get a minor for this device.\n");
 373                 goto error;
 374         }
 375
 376         i = le16_to_cpu(dev->udev->descriptor.bcdDevice);
 377
 378         dev_info(&interface->dev, "USBLCD Version %1d%1d.%1d%1d found "
 379                  "at address %d\n", (i & 0xF000)>>12, (i & 0xF00)>>8,
 380                  (i & 0xF0)>>4, (i & 0xF), dev->udev->devnum);
 381
 382         /* let the user know what node this device is now attached to */
 383         dev_info(&interface->dev, "USB LCD device now attached to USBLCD-%d\n",
 384                  interface->minor);
 385         return 0;
 386
 387 error:
 388         kref_put(&dev->kref, lcd_delete);
 389         return retval;
 390 }
 391
 392 static void lcd_draw_down(struct usb_lcd *dev)
 393 {
 394         int time;
 395
 396         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
 397         if (!time)
 398                 usb_kill_anchored_urbs(&dev->submitted);
 399 }
 400
 401 static int lcd_suspend(struct usb_interface *intf, pm_message_t message)
 402 {
 403         struct usb_lcd *dev = usb_get_intfdata(intf);
 404
 405         if (!dev)
 406                 return 0;
 407         lcd_draw_down(dev);
 408         return 0;
 409 }
 410
 411 static int lcd_resume(struct usb_interface *intf)
 412 {
 413         return 0;
 414 }
 415
 416 static void lcd_disconnect(struct usb_interface *interface)
 417 {
 418         struct usb_lcd *dev = usb_get_intfdata(interface);
 419         int minor = interface->minor;
 420
 421         /* give back our minor */
 422         usb_deregister_dev(interface, &lcd_class);
 423
 424         down_write(&dev->io_rwsem);
 425         dev->disconnected = 1;
 426         up_write(&dev->io_rwsem);
 427
 428         usb_kill_anchored_urbs(&dev->submitted);
 429
 430         /* decrement our usage count */
 431         kref_put(&dev->kref, lcd_delete);
 432
 433         dev_info(&interface->dev, "USB LCD #%d now disconnected\n", minor);
 434 }
 435
 436 static struct usb_driver lcd_driver = {
 437         .name =         "usblcd",
 438         .probe =        lcd_probe,
 439         .disconnect =   lcd_disconnect,
 440         .suspend =      lcd_suspend,
 441         .resume =       lcd_resume,
 442         .id_table =     id_table,
 443         .supports_autosuspend = 1,
 444 };
 445
 446 module_usb_driver(lcd_driver);
 447
 448 MODULE_AUTHOR("Georges Toth <g.toth@e-biz.lu>");
 449 MODULE_DESCRIPTION(DRIVER_VERSION);
 450 MODULE_LICENSE("GPL");