xref: /openbmc/linux/drivers/usb/serial/ssu100.c (revision 95e9fd10)
1 /*
2  * usb-serial driver for Quatech SSU-100
3  *
4  * based on ftdi_sio.c and the original serqt_usb.c from Quatech
5  *
6  */
7 
8 #include <linux/errno.h>
9 #include <linux/init.h>
10 #include <linux/slab.h>
11 #include <linux/tty.h>
12 #include <linux/tty_driver.h>
13 #include <linux/tty_flip.h>
14 #include <linux/module.h>
15 #include <linux/serial.h>
16 #include <linux/usb.h>
17 #include <linux/usb/serial.h>
18 #include <linux/serial_reg.h>
19 #include <linux/uaccess.h>
20 
21 #define QT_OPEN_CLOSE_CHANNEL       0xca
22 #define QT_SET_GET_DEVICE           0xc2
23 #define QT_SET_GET_REGISTER         0xc0
24 #define QT_GET_SET_PREBUF_TRIG_LVL  0xcc
25 #define QT_SET_ATF                  0xcd
26 #define QT_GET_SET_UART             0xc1
27 #define QT_TRANSFER_IN              0xc0
28 #define QT_HW_FLOW_CONTROL_MASK     0xc5
29 #define QT_SW_FLOW_CONTROL_MASK     0xc6
30 
31 #define  SERIAL_MSR_MASK            0xf0
32 
33 #define  SERIAL_CRTSCTS ((UART_MCR_RTS << 8) | UART_MSR_CTS)
34 
35 #define  SERIAL_EVEN_PARITY         (UART_LCR_PARITY | UART_LCR_EPAR)
36 
37 #define  MAX_BAUD_RATE              460800
38 
39 #define ATC_DISABLED                0x00
40 #define DUPMODE_BITS        0xc0
41 #define RR_BITS             0x03
42 #define LOOPMODE_BITS       0x41
43 #define RS232_MODE          0x00
44 #define RTSCTS_TO_CONNECTOR 0x40
45 #define CLKS_X4             0x02
46 #define FULLPWRBIT          0x00000080
47 #define NEXT_BOARD_POWER_BIT        0x00000004
48 
49 static bool debug;
50 
51 /* Version Information */
52 #define DRIVER_VERSION "v0.1"
53 #define DRIVER_DESC "Quatech SSU-100 USB to Serial Driver"
54 
55 #define	USB_VENDOR_ID_QUATECH	0x061d	/* Quatech VID */
56 #define QUATECH_SSU100	0xC020	/* SSU100 */
57 
58 static const struct usb_device_id id_table[] = {
59 	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_SSU100)},
60 	{}			/* Terminating entry */
61 };
62 MODULE_DEVICE_TABLE(usb, id_table);
63 
64 struct ssu100_port_private {
65 	spinlock_t status_lock;
66 	u8 shadowLSR;
67 	u8 shadowMSR;
68 	wait_queue_head_t delta_msr_wait; /* Used for TIOCMIWAIT */
69 	struct async_icount icount;
70 };
71 
72 static void ssu100_release(struct usb_serial *serial)
73 {
74 	struct ssu100_port_private *priv = usb_get_serial_port_data(*serial->port);
75 
76 	kfree(priv);
77 }
78 
79 static inline int ssu100_control_msg(struct usb_device *dev,
80 				     u8 request, u16 data, u16 index)
81 {
82 	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
83 			       request, 0x40, data, index,
84 			       NULL, 0, 300);
85 }
86 
87 static inline int ssu100_setdevice(struct usb_device *dev, u8 *data)
88 {
89 	u16 x = ((u16)(data[1] << 8) | (u16)(data[0]));
90 
91 	return ssu100_control_msg(dev, QT_SET_GET_DEVICE, x, 0);
92 }
93 
94 
95 static inline int ssu100_getdevice(struct usb_device *dev, u8 *data)
96 {
97 	return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
98 			       QT_SET_GET_DEVICE, 0xc0, 0, 0,
99 			       data, 3, 300);
100 }
101 
102 static inline int ssu100_getregister(struct usb_device *dev,
103 				     unsigned short uart,
104 				     unsigned short reg,
105 				     u8 *data)
106 {
107 	return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
108 			       QT_SET_GET_REGISTER, 0xc0, reg,
109 			       uart, data, sizeof(*data), 300);
110 
111 }
112 
113 
114 static inline int ssu100_setregister(struct usb_device *dev,
115 				     unsigned short uart,
116 				     unsigned short reg,
117 				     u16 data)
118 {
119 	u16 value = (data << 8) | reg;
120 
121 	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
122 			       QT_SET_GET_REGISTER, 0x40, value, uart,
123 			       NULL, 0, 300);
124 
125 }
126 
127 #define set_mctrl(dev, set)		update_mctrl((dev), (set), 0)
128 #define clear_mctrl(dev, clear)	update_mctrl((dev), 0, (clear))
129 
130 /* these do not deal with device that have more than 1 port */
131 static inline int update_mctrl(struct usb_device *dev, unsigned int set,
132 			       unsigned int clear)
133 {
134 	unsigned urb_value;
135 	int result;
136 
137 	if (((set | clear) & (TIOCM_DTR | TIOCM_RTS)) == 0) {
138 		dbg("%s - DTR|RTS not being set|cleared", __func__);
139 		return 0;	/* no change */
140 	}
141 
142 	clear &= ~set;	/* 'set' takes precedence over 'clear' */
143 	urb_value = 0;
144 	if (set & TIOCM_DTR)
145 		urb_value |= UART_MCR_DTR;
146 	if (set & TIOCM_RTS)
147 		urb_value |= UART_MCR_RTS;
148 
149 	result = ssu100_setregister(dev, 0, UART_MCR, urb_value);
150 	if (result < 0)
151 		dbg("%s Error from MODEM_CTRL urb", __func__);
152 
153 	return result;
154 }
155 
156 static int ssu100_initdevice(struct usb_device *dev)
157 {
158 	u8 *data;
159 	int result = 0;
160 
161 	data = kzalloc(3, GFP_KERNEL);
162 	if (!data)
163 		return -ENOMEM;
164 
165 	result = ssu100_getdevice(dev, data);
166 	if (result < 0) {
167 		dbg("%s - get_device failed %i", __func__, result);
168 		goto out;
169 	}
170 
171 	data[1] &= ~FULLPWRBIT;
172 
173 	result = ssu100_setdevice(dev, data);
174 	if (result < 0) {
175 		dbg("%s - setdevice failed %i", __func__, result);
176 		goto out;
177 	}
178 
179 	result = ssu100_control_msg(dev, QT_GET_SET_PREBUF_TRIG_LVL, 128, 0);
180 	if (result < 0) {
181 		dbg("%s - set prebuffer level failed %i", __func__, result);
182 		goto out;
183 	}
184 
185 	result = ssu100_control_msg(dev, QT_SET_ATF, ATC_DISABLED, 0);
186 	if (result < 0) {
187 		dbg("%s - set ATFprebuffer level failed %i", __func__, result);
188 		goto out;
189 	}
190 
191 	result = ssu100_getdevice(dev, data);
192 	if (result < 0) {
193 		dbg("%s - get_device failed %i", __func__, result);
194 		goto out;
195 	}
196 
197 	data[0] &= ~(RR_BITS | DUPMODE_BITS);
198 	data[0] |= CLKS_X4;
199 	data[1] &= ~(LOOPMODE_BITS);
200 	data[1] |= RS232_MODE;
201 
202 	result = ssu100_setdevice(dev, data);
203 	if (result < 0) {
204 		dbg("%s - setdevice failed %i", __func__, result);
205 		goto out;
206 	}
207 
208 out:	kfree(data);
209 	return result;
210 
211 }
212 
213 
214 static void ssu100_set_termios(struct tty_struct *tty,
215 			       struct usb_serial_port *port,
216 			       struct ktermios *old_termios)
217 {
218 	struct usb_device *dev = port->serial->dev;
219 	struct ktermios *termios = tty->termios;
220 	u16 baud, divisor, remainder;
221 	unsigned int cflag = termios->c_cflag;
222 	u16 urb_value = 0; /* will hold the new flags */
223 	int result;
224 
225 	if (cflag & PARENB) {
226 		if (cflag & PARODD)
227 			urb_value |= UART_LCR_PARITY;
228 		else
229 			urb_value |= SERIAL_EVEN_PARITY;
230 	}
231 
232 	switch (cflag & CSIZE) {
233 	case CS5:
234 		urb_value |= UART_LCR_WLEN5;
235 		break;
236 	case CS6:
237 		urb_value |= UART_LCR_WLEN6;
238 		break;
239 	case CS7:
240 		urb_value |= UART_LCR_WLEN7;
241 		break;
242 	default:
243 	case CS8:
244 		urb_value |= UART_LCR_WLEN8;
245 		break;
246 	}
247 
248 	baud = tty_get_baud_rate(tty);
249 	if (!baud)
250 		baud = 9600;
251 
252 	dbg("%s - got baud = %d\n", __func__, baud);
253 
254 
255 	divisor = MAX_BAUD_RATE / baud;
256 	remainder = MAX_BAUD_RATE % baud;
257 	if (((remainder * 2) >= baud) && (baud != 110))
258 		divisor++;
259 
260 	urb_value = urb_value << 8;
261 
262 	result = ssu100_control_msg(dev, QT_GET_SET_UART, divisor, urb_value);
263 	if (result < 0)
264 		dbg("%s - set uart failed", __func__);
265 
266 	if (cflag & CRTSCTS)
267 		result = ssu100_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
268 					    SERIAL_CRTSCTS, 0);
269 	else
270 		result = ssu100_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
271 					    0, 0);
272 	if (result < 0)
273 		dbg("%s - set HW flow control failed", __func__);
274 
275 	if (I_IXOFF(tty) || I_IXON(tty)) {
276 		u16 x = ((u16)(START_CHAR(tty) << 8) | (u16)(STOP_CHAR(tty)));
277 
278 		result = ssu100_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
279 					    x, 0);
280 	} else
281 		result = ssu100_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
282 					    0, 0);
283 
284 	if (result < 0)
285 		dbg("%s - set SW flow control failed", __func__);
286 
287 }
288 
289 
290 static int ssu100_open(struct tty_struct *tty, struct usb_serial_port *port)
291 {
292 	struct usb_device *dev = port->serial->dev;
293 	struct ssu100_port_private *priv = usb_get_serial_port_data(port);
294 	u8 *data;
295 	int result;
296 	unsigned long flags;
297 
298 	data = kzalloc(2, GFP_KERNEL);
299 	if (!data)
300 		return -ENOMEM;
301 
302 	result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
303 				 QT_OPEN_CLOSE_CHANNEL,
304 				 QT_TRANSFER_IN, 0x01,
305 				 0, data, 2, 300);
306 	if (result < 0) {
307 		dbg("%s - open failed %i", __func__, result);
308 		kfree(data);
309 		return result;
310 	}
311 
312 	spin_lock_irqsave(&priv->status_lock, flags);
313 	priv->shadowLSR = data[0];
314 	priv->shadowMSR = data[1];
315 	spin_unlock_irqrestore(&priv->status_lock, flags);
316 
317 	kfree(data);
318 
319 /* set to 9600 */
320 	result = ssu100_control_msg(dev, QT_GET_SET_UART, 0x30, 0x0300);
321 	if (result < 0)
322 		dbg("%s - set uart failed", __func__);
323 
324 	if (tty)
325 		ssu100_set_termios(tty, port, tty->termios);
326 
327 	return usb_serial_generic_open(tty, port);
328 }
329 
330 static void ssu100_close(struct usb_serial_port *port)
331 {
332 	usb_serial_generic_close(port);
333 }
334 
335 static int get_serial_info(struct usb_serial_port *port,
336 			   struct serial_struct __user *retinfo)
337 {
338 	struct serial_struct tmp;
339 
340 	if (!retinfo)
341 		return -EFAULT;
342 
343 	memset(&tmp, 0, sizeof(tmp));
344 	tmp.line		= port->serial->minor;
345 	tmp.port		= 0;
346 	tmp.irq			= 0;
347 	tmp.flags		= ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ;
348 	tmp.xmit_fifo_size	= port->bulk_out_size;
349 	tmp.baud_base		= 9600;
350 	tmp.close_delay		= 5*HZ;
351 	tmp.closing_wait	= 30*HZ;
352 
353 	if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
354 		return -EFAULT;
355 	return 0;
356 }
357 
358 static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
359 {
360 	struct ssu100_port_private *priv = usb_get_serial_port_data(port);
361 	struct async_icount prev, cur;
362 	unsigned long flags;
363 
364 	spin_lock_irqsave(&priv->status_lock, flags);
365 	prev = priv->icount;
366 	spin_unlock_irqrestore(&priv->status_lock, flags);
367 
368 	while (1) {
369 		wait_event_interruptible(priv->delta_msr_wait,
370 					 ((priv->icount.rng != prev.rng) ||
371 					  (priv->icount.dsr != prev.dsr) ||
372 					  (priv->icount.dcd != prev.dcd) ||
373 					  (priv->icount.cts != prev.cts)));
374 
375 		if (signal_pending(current))
376 			return -ERESTARTSYS;
377 
378 		spin_lock_irqsave(&priv->status_lock, flags);
379 		cur = priv->icount;
380 		spin_unlock_irqrestore(&priv->status_lock, flags);
381 
382 		if ((prev.rng == cur.rng) &&
383 		    (prev.dsr == cur.dsr) &&
384 		    (prev.dcd == cur.dcd) &&
385 		    (prev.cts == cur.cts))
386 			return -EIO;
387 
388 		if ((arg & TIOCM_RNG && (prev.rng != cur.rng)) ||
389 		    (arg & TIOCM_DSR && (prev.dsr != cur.dsr)) ||
390 		    (arg & TIOCM_CD  && (prev.dcd != cur.dcd)) ||
391 		    (arg & TIOCM_CTS && (prev.cts != cur.cts)))
392 			return 0;
393 	}
394 	return 0;
395 }
396 
397 static int ssu100_get_icount(struct tty_struct *tty,
398 			struct serial_icounter_struct *icount)
399 {
400 	struct usb_serial_port *port = tty->driver_data;
401 	struct ssu100_port_private *priv = usb_get_serial_port_data(port);
402 	struct async_icount cnow = priv->icount;
403 
404 	icount->cts = cnow.cts;
405 	icount->dsr = cnow.dsr;
406 	icount->rng = cnow.rng;
407 	icount->dcd = cnow.dcd;
408 	icount->rx = cnow.rx;
409 	icount->tx = cnow.tx;
410 	icount->frame = cnow.frame;
411 	icount->overrun = cnow.overrun;
412 	icount->parity = cnow.parity;
413 	icount->brk = cnow.brk;
414 	icount->buf_overrun = cnow.buf_overrun;
415 
416 	return 0;
417 }
418 
419 
420 
421 static int ssu100_ioctl(struct tty_struct *tty,
422 		    unsigned int cmd, unsigned long arg)
423 {
424 	struct usb_serial_port *port = tty->driver_data;
425 
426 	dbg("%s cmd 0x%04x", __func__, cmd);
427 
428 	switch (cmd) {
429 	case TIOCGSERIAL:
430 		return get_serial_info(port,
431 				       (struct serial_struct __user *) arg);
432 
433 	case TIOCMIWAIT:
434 		return wait_modem_info(port, arg);
435 
436 	default:
437 		break;
438 	}
439 
440 	dbg("%s arg not supported", __func__);
441 
442 	return -ENOIOCTLCMD;
443 }
444 
445 static int ssu100_attach(struct usb_serial *serial)
446 {
447 	struct ssu100_port_private *priv;
448 	struct usb_serial_port *port = *serial->port;
449 
450 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
451 	if (!priv) {
452 		dev_err(&port->dev, "%s- kmalloc(%Zd) failed.\n", __func__,
453 			sizeof(*priv));
454 		return -ENOMEM;
455 	}
456 
457 	spin_lock_init(&priv->status_lock);
458 	init_waitqueue_head(&priv->delta_msr_wait);
459 	usb_set_serial_port_data(port, priv);
460 
461 	return ssu100_initdevice(serial->dev);
462 }
463 
464 static int ssu100_tiocmget(struct tty_struct *tty)
465 {
466 	struct usb_serial_port *port = tty->driver_data;
467 	struct usb_device *dev = port->serial->dev;
468 	u8 *d;
469 	int r;
470 
471 	d = kzalloc(2, GFP_KERNEL);
472 	if (!d)
473 		return -ENOMEM;
474 
475 	r = ssu100_getregister(dev, 0, UART_MCR, d);
476 	if (r < 0)
477 		goto mget_out;
478 
479 	r = ssu100_getregister(dev, 0, UART_MSR, d+1);
480 	if (r < 0)
481 		goto mget_out;
482 
483 	r = (d[0] & UART_MCR_DTR ? TIOCM_DTR : 0) |
484 		(d[0] & UART_MCR_RTS ? TIOCM_RTS : 0) |
485 		(d[1] & UART_MSR_CTS ? TIOCM_CTS : 0) |
486 		(d[1] & UART_MSR_DCD ? TIOCM_CAR : 0) |
487 		(d[1] & UART_MSR_RI ? TIOCM_RI : 0) |
488 		(d[1] & UART_MSR_DSR ? TIOCM_DSR : 0);
489 
490 mget_out:
491 	kfree(d);
492 	return r;
493 }
494 
495 static int ssu100_tiocmset(struct tty_struct *tty,
496 			   unsigned int set, unsigned int clear)
497 {
498 	struct usb_serial_port *port = tty->driver_data;
499 	struct usb_device *dev = port->serial->dev;
500 
501 	return update_mctrl(dev, set, clear);
502 }
503 
504 static void ssu100_dtr_rts(struct usb_serial_port *port, int on)
505 {
506 	struct usb_device *dev = port->serial->dev;
507 
508 	mutex_lock(&port->serial->disc_mutex);
509 	if (!port->serial->disconnected) {
510 		/* Disable flow control */
511 		if (!on &&
512 		    ssu100_setregister(dev, 0, UART_MCR, 0) < 0)
513 			dev_err(&port->dev, "error from flowcontrol urb\n");
514 		/* drop RTS and DTR */
515 		if (on)
516 			set_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
517 		else
518 			clear_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
519 	}
520 	mutex_unlock(&port->serial->disc_mutex);
521 }
522 
523 static void ssu100_update_msr(struct usb_serial_port *port, u8 msr)
524 {
525 	struct ssu100_port_private *priv = usb_get_serial_port_data(port);
526 	unsigned long flags;
527 
528 	spin_lock_irqsave(&priv->status_lock, flags);
529 	priv->shadowMSR = msr;
530 	spin_unlock_irqrestore(&priv->status_lock, flags);
531 
532 	if (msr & UART_MSR_ANY_DELTA) {
533 		/* update input line counters */
534 		if (msr & UART_MSR_DCTS)
535 			priv->icount.cts++;
536 		if (msr & UART_MSR_DDSR)
537 			priv->icount.dsr++;
538 		if (msr & UART_MSR_DDCD)
539 			priv->icount.dcd++;
540 		if (msr & UART_MSR_TERI)
541 			priv->icount.rng++;
542 		wake_up_interruptible(&priv->delta_msr_wait);
543 	}
544 }
545 
546 static void ssu100_update_lsr(struct usb_serial_port *port, u8 lsr,
547 			      char *tty_flag)
548 {
549 	struct ssu100_port_private *priv = usb_get_serial_port_data(port);
550 	unsigned long flags;
551 
552 	spin_lock_irqsave(&priv->status_lock, flags);
553 	priv->shadowLSR = lsr;
554 	spin_unlock_irqrestore(&priv->status_lock, flags);
555 
556 	*tty_flag = TTY_NORMAL;
557 	if (lsr & UART_LSR_BRK_ERROR_BITS) {
558 		/* we always want to update icount, but we only want to
559 		 * update tty_flag for one case */
560 		if (lsr & UART_LSR_BI) {
561 			priv->icount.brk++;
562 			*tty_flag = TTY_BREAK;
563 			usb_serial_handle_break(port);
564 		}
565 		if (lsr & UART_LSR_PE) {
566 			priv->icount.parity++;
567 			if (*tty_flag == TTY_NORMAL)
568 				*tty_flag = TTY_PARITY;
569 		}
570 		if (lsr & UART_LSR_FE) {
571 			priv->icount.frame++;
572 			if (*tty_flag == TTY_NORMAL)
573 				*tty_flag = TTY_FRAME;
574 		}
575 		if (lsr & UART_LSR_OE){
576 			priv->icount.overrun++;
577 			if (*tty_flag == TTY_NORMAL)
578 				*tty_flag = TTY_OVERRUN;
579 		}
580 	}
581 
582 }
583 
584 static int ssu100_process_packet(struct urb *urb,
585 				 struct tty_struct *tty)
586 {
587 	struct usb_serial_port *port = urb->context;
588 	char *packet = (char *)urb->transfer_buffer;
589 	char flag = TTY_NORMAL;
590 	u32 len = urb->actual_length;
591 	int i;
592 	char *ch;
593 
594 	if ((len >= 4) &&
595 	    (packet[0] == 0x1b) && (packet[1] == 0x1b) &&
596 	    ((packet[2] == 0x00) || (packet[2] == 0x01))) {
597 		if (packet[2] == 0x00) {
598 			ssu100_update_lsr(port, packet[3], &flag);
599 			if (flag == TTY_OVERRUN)
600 				tty_insert_flip_char(tty, 0, TTY_OVERRUN);
601 		}
602 		if (packet[2] == 0x01)
603 			ssu100_update_msr(port, packet[3]);
604 
605 		len -= 4;
606 		ch = packet + 4;
607 	} else
608 		ch = packet;
609 
610 	if (!len)
611 		return 0;	/* status only */
612 
613 	if (port->port.console && port->sysrq) {
614 		for (i = 0; i < len; i++, ch++) {
615 			if (!usb_serial_handle_sysrq_char(port, *ch))
616 				tty_insert_flip_char(tty, *ch, flag);
617 		}
618 	} else
619 		tty_insert_flip_string_fixed_flag(tty, ch, flag, len);
620 
621 	return len;
622 }
623 
624 static void ssu100_process_read_urb(struct urb *urb)
625 {
626 	struct usb_serial_port *port = urb->context;
627 	struct tty_struct *tty;
628 	int count;
629 
630 	tty = tty_port_tty_get(&port->port);
631 	if (!tty)
632 		return;
633 
634 	count = ssu100_process_packet(urb, tty);
635 
636 	if (count)
637 		tty_flip_buffer_push(tty);
638 	tty_kref_put(tty);
639 }
640 
641 static struct usb_serial_driver ssu100_device = {
642 	.driver = {
643 		.owner = THIS_MODULE,
644 		.name = "ssu100",
645 	},
646 	.description	     = DRIVER_DESC,
647 	.id_table	     = id_table,
648 	.num_ports	     = 1,
649 	.open		     = ssu100_open,
650 	.close		     = ssu100_close,
651 	.attach              = ssu100_attach,
652 	.release             = ssu100_release,
653 	.dtr_rts             = ssu100_dtr_rts,
654 	.process_read_urb    = ssu100_process_read_urb,
655 	.tiocmget            = ssu100_tiocmget,
656 	.tiocmset            = ssu100_tiocmset,
657 	.get_icount	     = ssu100_get_icount,
658 	.ioctl               = ssu100_ioctl,
659 	.set_termios         = ssu100_set_termios,
660 	.disconnect          = usb_serial_generic_disconnect,
661 };
662 
663 static struct usb_serial_driver * const serial_drivers[] = {
664 	&ssu100_device, NULL
665 };
666 
667 module_usb_serial_driver(serial_drivers, id_table);
668 
669 MODULE_DESCRIPTION(DRIVER_DESC);
670 MODULE_LICENSE("GPL");
671 
672 module_param(debug, bool, S_IRUGO | S_IWUSR);
673 MODULE_PARM_DESC(debug, "Debug enabled or not");
674