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