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 
lcd_delete(struct kref * kref)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 
lcd_open(struct inode * inode,struct file * file)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 
lcd_release(struct inode * inode,struct file * file)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 
lcd_read(struct file * file,char __user * buffer,size_t count,loff_t * ppos)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 
lcd_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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 
lcd_write_bulk_callback(struct urb * urb)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 
lcd_write(struct file * file,const char __user * user_buffer,size_t count,loff_t * ppos)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 
lcd_probe(struct usb_interface * interface,const struct usb_device_id * id)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 
lcd_draw_down(struct usb_lcd * dev)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 
lcd_suspend(struct usb_interface * intf,pm_message_t message)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 
lcd_resume(struct usb_interface * intf)411 static int lcd_resume(struct usb_interface *intf)
412 {
413 	return 0;
414 }
415 
lcd_disconnect(struct usb_interface * interface)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");
451