xref: /openbmc/linux/drivers/parport/share.c (revision 7c0bf4da)
1 /*
2  * Parallel-port resource manager code.
3  *
4  * Authors: David Campbell <campbell@tirian.che.curtin.edu.au>
5  *          Tim Waugh <tim@cyberelk.demon.co.uk>
6  *          Jose Renau <renau@acm.org>
7  *          Philip Blundell <philb@gnu.org>
8  *	    Andrea Arcangeli
9  *
10  * based on work by Grant Guenther <grant@torque.net>
11  *          and Philip Blundell
12  *
13  * Any part of this program may be used in documents licensed under
14  * the GNU Free Documentation License, Version 1.1 or any later version
15  * published by the Free Software Foundation.
16  */
17 
18 #undef PARPORT_DEBUG_SHARING		/* undef for production */
19 
20 #include <linux/module.h>
21 #include <linux/string.h>
22 #include <linux/threads.h>
23 #include <linux/parport.h>
24 #include <linux/delay.h>
25 #include <linux/errno.h>
26 #include <linux/interrupt.h>
27 #include <linux/ioport.h>
28 #include <linux/kernel.h>
29 #include <linux/slab.h>
30 #include <linux/sched/signal.h>
31 #include <linux/kmod.h>
32 #include <linux/device.h>
33 
34 #include <linux/spinlock.h>
35 #include <linux/mutex.h>
36 #include <asm/irq.h>
37 
38 #undef PARPORT_PARANOID
39 
40 #define PARPORT_DEFAULT_TIMESLICE	(HZ/5)
41 
42 unsigned long parport_default_timeslice = PARPORT_DEFAULT_TIMESLICE;
43 int parport_default_spintime =  DEFAULT_SPIN_TIME;
44 
45 static LIST_HEAD(portlist);
46 static DEFINE_SPINLOCK(parportlist_lock);
47 
48 /* list of all allocated ports, sorted by ->number */
49 static LIST_HEAD(all_ports);
50 static DEFINE_SPINLOCK(full_list_lock);
51 
52 static LIST_HEAD(drivers);
53 
54 static DEFINE_MUTEX(registration_lock);
55 
56 /* What you can do to a port that's gone away.. */
dead_write_lines(struct parport * p,unsigned char b)57 static void dead_write_lines(struct parport *p, unsigned char b){}
dead_read_lines(struct parport * p)58 static unsigned char dead_read_lines(struct parport *p) { return 0; }
dead_frob_lines(struct parport * p,unsigned char b,unsigned char c)59 static unsigned char dead_frob_lines(struct parport *p, unsigned char b,
60 			     unsigned char c) { return 0; }
dead_onearg(struct parport * p)61 static void dead_onearg(struct parport *p){}
dead_initstate(struct pardevice * d,struct parport_state * s)62 static void dead_initstate(struct pardevice *d, struct parport_state *s) { }
dead_state(struct parport * p,struct parport_state * s)63 static void dead_state(struct parport *p, struct parport_state *s) { }
dead_write(struct parport * p,const void * b,size_t l,int f)64 static size_t dead_write(struct parport *p, const void *b, size_t l, int f)
65 { return 0; }
dead_read(struct parport * p,void * b,size_t l,int f)66 static size_t dead_read(struct parport *p, void *b, size_t l, int f)
67 { return 0; }
68 static struct parport_operations dead_ops = {
69 	.write_data	= dead_write_lines,	/* data */
70 	.read_data	= dead_read_lines,
71 
72 	.write_control	= dead_write_lines,	/* control */
73 	.read_control	= dead_read_lines,
74 	.frob_control	= dead_frob_lines,
75 
76 	.read_status	= dead_read_lines,	/* status */
77 
78 	.enable_irq	= dead_onearg,		/* enable_irq */
79 	.disable_irq	= dead_onearg,		/* disable_irq */
80 
81 	.data_forward	= dead_onearg,		/* data_forward */
82 	.data_reverse	= dead_onearg,		/* data_reverse */
83 
84 	.init_state	= dead_initstate,	/* init_state */
85 	.save_state	= dead_state,
86 	.restore_state	= dead_state,
87 
88 	.epp_write_data	= dead_write,		/* epp */
89 	.epp_read_data	= dead_read,
90 	.epp_write_addr	= dead_write,
91 	.epp_read_addr	= dead_read,
92 
93 	.ecp_write_data	= dead_write,		/* ecp */
94 	.ecp_read_data	= dead_read,
95 	.ecp_write_addr	= dead_write,
96 
97 	.compat_write_data	= dead_write,	/* compat */
98 	.nibble_read_data	= dead_read,	/* nibble */
99 	.byte_read_data		= dead_read,	/* byte */
100 
101 	.owner		= NULL,
102 };
103 
104 static struct device_type parport_device_type = {
105 	.name = "parport",
106 };
107 
is_parport(struct device * dev)108 static int is_parport(struct device *dev)
109 {
110 	return dev->type == &parport_device_type;
111 }
112 
parport_probe(struct device * dev)113 static int parport_probe(struct device *dev)
114 {
115 	struct parport_driver *drv;
116 
117 	if (is_parport(dev))
118 		return -ENODEV;
119 
120 	drv = to_parport_driver(dev->driver);
121 	if (!drv->probe) {
122 		/* if driver has not defined a custom probe */
123 		struct pardevice *par_dev = to_pardevice(dev);
124 
125 		if (strcmp(par_dev->name, drv->name))
126 			return -ENODEV;
127 		return 0;
128 	}
129 	/* if driver defined its own probe */
130 	return drv->probe(to_pardevice(dev));
131 }
132 
133 static struct bus_type parport_bus_type = {
134 	.name = "parport",
135 	.probe = parport_probe,
136 };
137 
parport_bus_init(void)138 int parport_bus_init(void)
139 {
140 	return bus_register(&parport_bus_type);
141 }
142 
parport_bus_exit(void)143 void parport_bus_exit(void)
144 {
145 	bus_unregister(&parport_bus_type);
146 }
147 
148 /*
149  * iterates through all the drivers registered with the bus and sends the port
150  * details to the match_port callback of the driver, so that the driver can
151  * know about the new port that just registered with the bus and decide if it
152  * wants to use this new port.
153  */
driver_check(struct device_driver * dev_drv,void * _port)154 static int driver_check(struct device_driver *dev_drv, void *_port)
155 {
156 	struct parport *port = _port;
157 	struct parport_driver *drv = to_parport_driver(dev_drv);
158 
159 	if (drv->match_port)
160 		drv->match_port(port);
161 	return 0;
162 }
163 
164 /* Call attach(port) for each registered driver. */
attach_driver_chain(struct parport * port)165 static void attach_driver_chain(struct parport *port)
166 {
167 	/* caller has exclusive registration_lock */
168 	struct parport_driver *drv;
169 
170 	list_for_each_entry(drv, &drivers, list)
171 		drv->attach(port);
172 
173 	/*
174 	 * call the driver_check function of the drivers registered in
175 	 * new device model
176 	 */
177 
178 	bus_for_each_drv(&parport_bus_type, NULL, port, driver_check);
179 }
180 
driver_detach(struct device_driver * _drv,void * _port)181 static int driver_detach(struct device_driver *_drv, void *_port)
182 {
183 	struct parport *port = _port;
184 	struct parport_driver *drv = to_parport_driver(_drv);
185 
186 	if (drv->detach)
187 		drv->detach(port);
188 	return 0;
189 }
190 
191 /* Call detach(port) for each registered driver. */
detach_driver_chain(struct parport * port)192 static void detach_driver_chain(struct parport *port)
193 {
194 	struct parport_driver *drv;
195 	/* caller has exclusive registration_lock */
196 	list_for_each_entry(drv, &drivers, list)
197 		drv->detach(port);
198 
199 	/*
200 	 * call the detach function of the drivers registered in
201 	 * new device model
202 	 */
203 
204 	bus_for_each_drv(&parport_bus_type, NULL, port, driver_detach);
205 }
206 
207 /* Ask kmod for some lowlevel drivers. */
get_lowlevel_driver(void)208 static void get_lowlevel_driver(void)
209 {
210 	/*
211 	 * There is no actual module called this: you should set
212 	 * up an alias for modutils.
213 	 */
214 	request_module("parport_lowlevel");
215 }
216 
217 /*
218  * iterates through all the devices connected to the bus and sends the device
219  * details to the match_port callback of the driver, so that the driver can
220  * know what are all the ports that are connected to the bus and choose the
221  * port to which it wants to register its device.
222  */
port_check(struct device * dev,void * dev_drv)223 static int port_check(struct device *dev, void *dev_drv)
224 {
225 	struct parport_driver *drv = dev_drv;
226 
227 	/* only send ports, do not send other devices connected to bus */
228 	if (is_parport(dev))
229 		drv->match_port(to_parport_dev(dev));
230 	return 0;
231 }
232 
233 /*
234  * Iterates through all the devices connected to the bus and return 1
235  * if the device is a parallel port.
236  */
237 
port_detect(struct device * dev,void * dev_drv)238 static int port_detect(struct device *dev, void *dev_drv)
239 {
240 	if (is_parport(dev))
241 		return 1;
242 	return 0;
243 }
244 
245 /**
246  *	__parport_register_driver - register a parallel port device driver
247  *	@drv: structure describing the driver
248  *	@owner: owner module of drv
249  *	@mod_name: module name string
250  *
251  *	This can be called by a parallel port device driver in order
252  *	to receive notifications about ports being found in the
253  *	system, as well as ports no longer available.
254  *
255  *	If devmodel is true then the new device model is used
256  *	for registration.
257  *
258  *	The @drv structure is allocated by the caller and must not be
259  *	deallocated until after calling parport_unregister_driver().
260  *
261  *	If using the non device model:
262  *	The driver's attach() function may block.  The port that
263  *	attach() is given will be valid for the duration of the
264  *	callback, but if the driver wants to take a copy of the
265  *	pointer it must call parport_get_port() to do so.  Calling
266  *	parport_register_device() on that port will do this for you.
267  *
268  *	The driver's detach() function may block.  The port that
269  *	detach() is given will be valid for the duration of the
270  *	callback, but if the driver wants to take a copy of the
271  *	pointer it must call parport_get_port() to do so.
272  *
273  *
274  *	Returns 0 on success. The non device model will always succeeds.
275  *	but the new device model can fail and will return the error code.
276  **/
277 
__parport_register_driver(struct parport_driver * drv,struct module * owner,const char * mod_name)278 int __parport_register_driver(struct parport_driver *drv, struct module *owner,
279 			      const char *mod_name)
280 {
281 	/* using device model */
282 	int ret;
283 
284 	/* initialize common driver fields */
285 	drv->driver.name = drv->name;
286 	drv->driver.bus = &parport_bus_type;
287 	drv->driver.owner = owner;
288 	drv->driver.mod_name = mod_name;
289 	ret = driver_register(&drv->driver);
290 	if (ret)
291 		return ret;
292 
293 	/*
294 	 * check if bus has any parallel port registered, if
295 	 * none is found then load the lowlevel driver.
296 	 */
297 	ret = bus_for_each_dev(&parport_bus_type, NULL, NULL,
298 			       port_detect);
299 	if (!ret)
300 		get_lowlevel_driver();
301 
302 	mutex_lock(&registration_lock);
303 	if (drv->match_port)
304 		bus_for_each_dev(&parport_bus_type, NULL, drv,
305 				 port_check);
306 	mutex_unlock(&registration_lock);
307 
308 	return 0;
309 }
310 EXPORT_SYMBOL(__parport_register_driver);
311 
port_detach(struct device * dev,void * _drv)312 static int port_detach(struct device *dev, void *_drv)
313 {
314 	struct parport_driver *drv = _drv;
315 
316 	if (is_parport(dev) && drv->detach)
317 		drv->detach(to_parport_dev(dev));
318 
319 	return 0;
320 }
321 
322 /**
323  *	parport_unregister_driver - deregister a parallel port device driver
324  *	@drv: structure describing the driver that was given to
325  *	      parport_register_driver()
326  *
327  *	This should be called by a parallel port device driver that
328  *	has registered itself using parport_register_driver() when it
329  *	is about to be unloaded.
330  *
331  *	When it returns, the driver's attach() routine will no longer
332  *	be called, and for each port that attach() was called for, the
333  *	detach() routine will have been called.
334  *
335  *	All the driver's attach() and detach() calls are guaranteed to have
336  *	finished by the time this function returns.
337  **/
338 
parport_unregister_driver(struct parport_driver * drv)339 void parport_unregister_driver(struct parport_driver *drv)
340 {
341 	mutex_lock(&registration_lock);
342 	bus_for_each_dev(&parport_bus_type, NULL, drv, port_detach);
343 	driver_unregister(&drv->driver);
344 	mutex_unlock(&registration_lock);
345 }
346 EXPORT_SYMBOL(parport_unregister_driver);
347 
free_port(struct device * dev)348 static void free_port(struct device *dev)
349 {
350 	int d;
351 	struct parport *port = to_parport_dev(dev);
352 
353 	spin_lock(&full_list_lock);
354 	list_del(&port->full_list);
355 	spin_unlock(&full_list_lock);
356 	for (d = 0; d < 5; d++) {
357 		kfree(port->probe_info[d].class_name);
358 		kfree(port->probe_info[d].mfr);
359 		kfree(port->probe_info[d].model);
360 		kfree(port->probe_info[d].cmdset);
361 		kfree(port->probe_info[d].description);
362 	}
363 
364 	kfree(port->name);
365 	kfree(port);
366 }
367 
368 /**
369  *	parport_get_port - increment a port's reference count
370  *	@port: the port
371  *
372  *	This ensures that a struct parport pointer remains valid
373  *	until the matching parport_put_port() call.
374  **/
375 
parport_get_port(struct parport * port)376 struct parport *parport_get_port(struct parport *port)
377 {
378 	struct device *dev = get_device(&port->bus_dev);
379 
380 	return to_parport_dev(dev);
381 }
382 EXPORT_SYMBOL(parport_get_port);
383 
parport_del_port(struct parport * port)384 void parport_del_port(struct parport *port)
385 {
386 	device_unregister(&port->bus_dev);
387 }
388 EXPORT_SYMBOL(parport_del_port);
389 
390 /**
391  *	parport_put_port - decrement a port's reference count
392  *	@port: the port
393  *
394  *	This should be called once for each call to parport_get_port(),
395  *	once the port is no longer needed. When the reference count reaches
396  *	zero (port is no longer used), free_port is called.
397  **/
398 
parport_put_port(struct parport * port)399 void parport_put_port(struct parport *port)
400 {
401 	put_device(&port->bus_dev);
402 }
403 EXPORT_SYMBOL(parport_put_port);
404 
405 /**
406  *	parport_register_port - register a parallel port
407  *	@base: base I/O address
408  *	@irq: IRQ line
409  *	@dma: DMA channel
410  *	@ops: pointer to the port driver's port operations structure
411  *
412  *	When a parallel port (lowlevel) driver finds a port that
413  *	should be made available to parallel port device drivers, it
414  *	should call parport_register_port().  The @base, @irq, and
415  *	@dma parameters are for the convenience of port drivers, and
416  *	for ports where they aren't meaningful needn't be set to
417  *	anything special.  They can be altered afterwards by adjusting
418  *	the relevant members of the parport structure that is returned
419  *	and represents the port.  They should not be tampered with
420  *	after calling parport_announce_port, however.
421  *
422  *	If there are parallel port device drivers in the system that
423  *	have registered themselves using parport_register_driver(),
424  *	they are not told about the port at this time; that is done by
425  *	parport_announce_port().
426  *
427  *	The @ops structure is allocated by the caller, and must not be
428  *	deallocated before calling parport_remove_port().
429  *
430  *	If there is no memory to allocate a new parport structure,
431  *	this function will return %NULL.
432  **/
433 
parport_register_port(unsigned long base,int irq,int dma,struct parport_operations * ops)434 struct parport *parport_register_port(unsigned long base, int irq, int dma,
435 				      struct parport_operations *ops)
436 {
437 	struct list_head *l;
438 	struct parport *tmp;
439 	int num;
440 	int device;
441 	char *name;
442 	int ret;
443 
444 	tmp = kzalloc(sizeof(struct parport), GFP_KERNEL);
445 	if (!tmp)
446 		return NULL;
447 
448 	/* Init our structure */
449 	tmp->base = base;
450 	tmp->irq = irq;
451 	tmp->dma = dma;
452 	tmp->muxport = tmp->daisy = tmp->muxsel = -1;
453 	tmp->modes = 0;
454 	INIT_LIST_HEAD(&tmp->list);
455 	tmp->devices = tmp->cad = NULL;
456 	tmp->flags = 0;
457 	tmp->ops = ops;
458 	tmp->physport = tmp;
459 	memset(tmp->probe_info, 0, 5 * sizeof(struct parport_device_info));
460 	rwlock_init(&tmp->cad_lock);
461 	spin_lock_init(&tmp->waitlist_lock);
462 	spin_lock_init(&tmp->pardevice_lock);
463 	tmp->ieee1284.mode = IEEE1284_MODE_COMPAT;
464 	tmp->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
465 	sema_init(&tmp->ieee1284.irq, 0);
466 	tmp->spintime = parport_default_spintime;
467 	atomic_set(&tmp->ref_count, 1);
468 	INIT_LIST_HEAD(&tmp->full_list);
469 
470 	name = kmalloc(PARPORT_NAME_MAX_LEN, GFP_KERNEL);
471 	if (!name) {
472 		kfree(tmp);
473 		return NULL;
474 	}
475 	/* Search for the lowest free parport number. */
476 
477 	spin_lock(&full_list_lock);
478 	for (l = all_ports.next, num = 0; l != &all_ports; l = l->next, num++) {
479 		struct parport *p = list_entry(l, struct parport, full_list);
480 		if (p->number != num)
481 			break;
482 	}
483 	tmp->portnum = tmp->number = num;
484 	list_add_tail(&tmp->full_list, l);
485 	spin_unlock(&full_list_lock);
486 
487 	/*
488 	 * Now that the portnum is known finish doing the Init.
489 	 */
490 	sprintf(name, "parport%d", tmp->portnum = tmp->number);
491 	tmp->name = name;
492 	tmp->bus_dev.bus = &parport_bus_type;
493 	tmp->bus_dev.release = free_port;
494 	dev_set_name(&tmp->bus_dev, name);
495 	tmp->bus_dev.type = &parport_device_type;
496 
497 	for (device = 0; device < 5; device++)
498 		/* assume the worst */
499 		tmp->probe_info[device].class = PARPORT_CLASS_LEGACY;
500 
501 	tmp->waithead = tmp->waittail = NULL;
502 
503 	ret = device_register(&tmp->bus_dev);
504 	if (ret) {
505 		put_device(&tmp->bus_dev);
506 		return NULL;
507 	}
508 
509 	return tmp;
510 }
511 EXPORT_SYMBOL(parport_register_port);
512 
513 /**
514  *	parport_announce_port - tell device drivers about a parallel port
515  *	@port: parallel port to announce
516  *
517  *	After a port driver has registered a parallel port with
518  *	parport_register_port, and performed any necessary
519  *	initialisation or adjustments, it should call
520  *	parport_announce_port() in order to notify all device drivers
521  *	that have called parport_register_driver().  Their attach()
522  *	functions will be called, with @port as the parameter.
523  **/
524 
parport_announce_port(struct parport * port)525 void parport_announce_port(struct parport *port)
526 {
527 	int i;
528 
529 #ifdef CONFIG_PARPORT_1284
530 	/* Analyse the IEEE1284.3 topology of the port. */
531 	parport_daisy_init(port);
532 #endif
533 
534 	if (!port->dev)
535 		pr_warn("%s: fix this legacy no-device port driver!\n",
536 			port->name);
537 
538 	parport_proc_register(port);
539 	mutex_lock(&registration_lock);
540 	spin_lock_irq(&parportlist_lock);
541 	list_add_tail(&port->list, &portlist);
542 	for (i = 1; i < 3; i++) {
543 		struct parport *slave = port->slaves[i-1];
544 		if (slave)
545 			list_add_tail(&slave->list, &portlist);
546 	}
547 	spin_unlock_irq(&parportlist_lock);
548 
549 	/* Let drivers know that new port(s) has arrived. */
550 	attach_driver_chain(port);
551 	for (i = 1; i < 3; i++) {
552 		struct parport *slave = port->slaves[i-1];
553 		if (slave)
554 			attach_driver_chain(slave);
555 	}
556 	mutex_unlock(&registration_lock);
557 }
558 EXPORT_SYMBOL(parport_announce_port);
559 
560 /**
561  *	parport_remove_port - deregister a parallel port
562  *	@port: parallel port to deregister
563  *
564  *	When a parallel port driver is forcibly unloaded, or a
565  *	parallel port becomes inaccessible, the port driver must call
566  *	this function in order to deal with device drivers that still
567  *	want to use it.
568  *
569  *	The parport structure associated with the port has its
570  *	operations structure replaced with one containing 'null'
571  *	operations that return errors or just don't do anything.
572  *
573  *	Any drivers that have registered themselves using
574  *	parport_register_driver() are notified that the port is no
575  *	longer accessible by having their detach() routines called
576  *	with @port as the parameter.
577  **/
578 
parport_remove_port(struct parport * port)579 void parport_remove_port(struct parport *port)
580 {
581 	int i;
582 
583 	mutex_lock(&registration_lock);
584 
585 	/* Spread the word. */
586 	detach_driver_chain(port);
587 
588 #ifdef CONFIG_PARPORT_1284
589 	/* Forget the IEEE1284.3 topology of the port. */
590 	parport_daisy_fini(port);
591 	for (i = 1; i < 3; i++) {
592 		struct parport *slave = port->slaves[i-1];
593 		if (!slave)
594 			continue;
595 		detach_driver_chain(slave);
596 		parport_daisy_fini(slave);
597 	}
598 #endif
599 
600 	port->ops = &dead_ops;
601 	spin_lock(&parportlist_lock);
602 	list_del_init(&port->list);
603 	for (i = 1; i < 3; i++) {
604 		struct parport *slave = port->slaves[i-1];
605 		if (slave)
606 			list_del_init(&slave->list);
607 	}
608 	spin_unlock(&parportlist_lock);
609 
610 	mutex_unlock(&registration_lock);
611 
612 	parport_proc_unregister(port);
613 
614 	for (i = 1; i < 3; i++) {
615 		struct parport *slave = port->slaves[i-1];
616 		if (slave)
617 			parport_put_port(slave);
618 	}
619 }
620 EXPORT_SYMBOL(parport_remove_port);
621 
free_pardevice(struct device * dev)622 static void free_pardevice(struct device *dev)
623 {
624 	struct pardevice *par_dev = to_pardevice(dev);
625 
626 	kfree(par_dev->name);
627 	kfree(par_dev);
628 }
629 
630 /**
631  *	parport_register_dev_model - register a device on a parallel port
632  *	@port: port to which the device is attached
633  *	@name: a name to refer to the device
634  *	@par_dev_cb: struct containing callbacks
635  *	@id: device number to be given to the device
636  *
637  *	This function, called by parallel port device drivers,
638  *	declares that a device is connected to a port, and tells the
639  *	system all it needs to know.
640  *
641  *	The struct pardev_cb contains pointer to callbacks. preemption
642  *	callback function, @preempt, is called when this device driver
643  *	has claimed access to the port but another device driver wants
644  *	to use it.  It is given, @private, as its parameter, and should
645  *	return zero if it is willing for the system to release the port
646  *	to another driver on its behalf. If it wants to keep control of
647  *	the port it should return non-zero, and no action will be taken.
648  *	It is good manners for the driver to try to release the port at
649  *	the earliest opportunity after its preemption callback rejects a
650  *	preemption attempt. Note that if a preemption callback is happy
651  *	for preemption to go ahead, there is no need to release the
652  *	port; it is done automatically. This function may not block, as
653  *	it may be called from interrupt context. If the device driver
654  *	does not support preemption, @preempt can be %NULL.
655  *
656  *	The wake-up ("kick") callback function, @wakeup, is called when
657  *	the port is available to be claimed for exclusive access; that
658  *	is, parport_claim() is guaranteed to succeed when called from
659  *	inside the wake-up callback function.  If the driver wants to
660  *	claim the port it should do so; otherwise, it need not take
661  *	any action.  This function may not block, as it may be called
662  *	from interrupt context.  If the device driver does not want to
663  *	be explicitly invited to claim the port in this way, @wakeup can
664  *	be %NULL.
665  *
666  *	The interrupt handler, @irq_func, is called when an interrupt
667  *	arrives from the parallel port.  Note that if a device driver
668  *	wants to use interrupts it should use parport_enable_irq(),
669  *	and can also check the irq member of the parport structure
670  *	representing the port.
671  *
672  *	The parallel port (lowlevel) driver is the one that has called
673  *	request_irq() and whose interrupt handler is called first.
674  *	This handler does whatever needs to be done to the hardware to
675  *	acknowledge the interrupt (for PC-style ports there is nothing
676  *	special to be done).  It then tells the IEEE 1284 code about
677  *	the interrupt, which may involve reacting to an IEEE 1284
678  *	event depending on the current IEEE 1284 phase.  After this,
679  *	it calls @irq_func.  Needless to say, @irq_func will be called
680  *	from interrupt context, and may not block.
681  *
682  *	The %PARPORT_DEV_EXCL flag is for preventing port sharing, and
683  *	so should only be used when sharing the port with other device
684  *	drivers is impossible and would lead to incorrect behaviour.
685  *	Use it sparingly!  Normally, @flags will be zero.
686  *
687  *	This function returns a pointer to a structure that represents
688  *	the device on the port, or %NULL if there is not enough memory
689  *	to allocate space for that structure.
690  **/
691 
692 struct pardevice *
parport_register_dev_model(struct parport * port,const char * name,const struct pardev_cb * par_dev_cb,int id)693 parport_register_dev_model(struct parport *port, const char *name,
694 			   const struct pardev_cb *par_dev_cb, int id)
695 {
696 	struct pardevice *par_dev;
697 	int ret;
698 	char *devname;
699 
700 	if (port->physport->flags & PARPORT_FLAG_EXCL) {
701 		/* An exclusive device is registered. */
702 		pr_err("%s: no more devices allowed\n", port->name);
703 		return NULL;
704 	}
705 
706 	if (par_dev_cb->flags & PARPORT_DEV_LURK) {
707 		if (!par_dev_cb->preempt || !par_dev_cb->wakeup) {
708 			pr_info("%s: refused to register lurking device (%s) without callbacks\n",
709 				port->name, name);
710 			return NULL;
711 		}
712 	}
713 
714 	if (par_dev_cb->flags & PARPORT_DEV_EXCL) {
715 		if (port->physport->devices) {
716 			/*
717 			 * If a device is already registered and this new
718 			 * device wants exclusive access, then no need to
719 			 * continue as we can not grant exclusive access to
720 			 * this device.
721 			 */
722 			pr_err("%s: cannot grant exclusive access for device %s\n",
723 			       port->name, name);
724 			return NULL;
725 		}
726 	}
727 
728 	if (!try_module_get(port->ops->owner))
729 		return NULL;
730 
731 	parport_get_port(port);
732 
733 	par_dev = kzalloc(sizeof(*par_dev), GFP_KERNEL);
734 	if (!par_dev)
735 		goto err_put_port;
736 
737 	par_dev->state = kzalloc(sizeof(*par_dev->state), GFP_KERNEL);
738 	if (!par_dev->state)
739 		goto err_put_par_dev;
740 
741 	devname = kstrdup(name, GFP_KERNEL);
742 	if (!devname)
743 		goto err_free_par_dev;
744 
745 	par_dev->name = devname;
746 	par_dev->port = port;
747 	par_dev->daisy = -1;
748 	par_dev->preempt = par_dev_cb->preempt;
749 	par_dev->wakeup = par_dev_cb->wakeup;
750 	par_dev->private = par_dev_cb->private;
751 	par_dev->flags = par_dev_cb->flags;
752 	par_dev->irq_func = par_dev_cb->irq_func;
753 	par_dev->waiting = 0;
754 	par_dev->timeout = 5 * HZ;
755 
756 	par_dev->dev.parent = &port->bus_dev;
757 	par_dev->dev.bus = &parport_bus_type;
758 	ret = dev_set_name(&par_dev->dev, "%s.%d", devname, id);
759 	if (ret)
760 		goto err_free_devname;
761 	par_dev->dev.release = free_pardevice;
762 	par_dev->devmodel = true;
763 	ret = device_register(&par_dev->dev);
764 	if (ret) {
765 		kfree(par_dev->state);
766 		put_device(&par_dev->dev);
767 		goto err_put_port;
768 	}
769 
770 	/* Chain this onto the list */
771 	par_dev->prev = NULL;
772 	/*
773 	 * This function must not run from an irq handler so we don' t need
774 	 * to clear irq on the local CPU. -arca
775 	 */
776 	spin_lock(&port->physport->pardevice_lock);
777 
778 	if (par_dev_cb->flags & PARPORT_DEV_EXCL) {
779 		if (port->physport->devices) {
780 			spin_unlock(&port->physport->pardevice_lock);
781 			pr_debug("%s: cannot grant exclusive access for device %s\n",
782 				 port->name, name);
783 			kfree(par_dev->state);
784 			device_unregister(&par_dev->dev);
785 			goto err_put_port;
786 		}
787 		port->flags |= PARPORT_FLAG_EXCL;
788 	}
789 
790 	par_dev->next = port->physport->devices;
791 	wmb();	/*
792 		 * Make sure that tmp->next is written before it's
793 		 * added to the list; see comments marked 'no locking
794 		 * required'
795 		 */
796 	if (port->physport->devices)
797 		port->physport->devices->prev = par_dev;
798 	port->physport->devices = par_dev;
799 	spin_unlock(&port->physport->pardevice_lock);
800 
801 	init_waitqueue_head(&par_dev->wait_q);
802 	par_dev->timeslice = parport_default_timeslice;
803 	par_dev->waitnext = NULL;
804 	par_dev->waitprev = NULL;
805 
806 	/*
807 	 * This has to be run as last thing since init_state may need other
808 	 * pardevice fields. -arca
809 	 */
810 	port->ops->init_state(par_dev, par_dev->state);
811 	if (!test_and_set_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags)) {
812 		port->proc_device = par_dev;
813 		parport_device_proc_register(par_dev);
814 	}
815 
816 	return par_dev;
817 
818 err_free_devname:
819 	kfree(devname);
820 err_free_par_dev:
821 	kfree(par_dev->state);
822 err_put_par_dev:
823 	if (!par_dev->devmodel)
824 		kfree(par_dev);
825 err_put_port:
826 	parport_put_port(port);
827 	module_put(port->ops->owner);
828 
829 	return NULL;
830 }
831 EXPORT_SYMBOL(parport_register_dev_model);
832 
833 /**
834  *	parport_unregister_device - deregister a device on a parallel port
835  *	@dev: pointer to structure representing device
836  *
837  *	This undoes the effect of parport_register_device().
838  **/
839 
parport_unregister_device(struct pardevice * dev)840 void parport_unregister_device(struct pardevice *dev)
841 {
842 	struct parport *port;
843 
844 #ifdef PARPORT_PARANOID
845 	if (!dev) {
846 		pr_err("%s: passed NULL\n", __func__);
847 		return;
848 	}
849 #endif
850 
851 	port = dev->port->physport;
852 
853 	if (port->proc_device == dev) {
854 		port->proc_device = NULL;
855 		clear_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags);
856 		parport_device_proc_unregister(dev);
857 	}
858 
859 	if (port->cad == dev) {
860 		printk(KERN_DEBUG "%s: %s forgot to release port\n",
861 		       port->name, dev->name);
862 		parport_release(dev);
863 	}
864 
865 	spin_lock(&port->pardevice_lock);
866 	if (dev->next)
867 		dev->next->prev = dev->prev;
868 	if (dev->prev)
869 		dev->prev->next = dev->next;
870 	else
871 		port->devices = dev->next;
872 
873 	if (dev->flags & PARPORT_DEV_EXCL)
874 		port->flags &= ~PARPORT_FLAG_EXCL;
875 
876 	spin_unlock(&port->pardevice_lock);
877 
878 	/*
879 	 * Make sure we haven't left any pointers around in the wait
880 	 * list.
881 	 */
882 	spin_lock_irq(&port->waitlist_lock);
883 	if (dev->waitprev || dev->waitnext || port->waithead == dev) {
884 		if (dev->waitprev)
885 			dev->waitprev->waitnext = dev->waitnext;
886 		else
887 			port->waithead = dev->waitnext;
888 		if (dev->waitnext)
889 			dev->waitnext->waitprev = dev->waitprev;
890 		else
891 			port->waittail = dev->waitprev;
892 	}
893 	spin_unlock_irq(&port->waitlist_lock);
894 
895 	kfree(dev->state);
896 	device_unregister(&dev->dev);
897 
898 	module_put(port->ops->owner);
899 	parport_put_port(port);
900 }
901 EXPORT_SYMBOL(parport_unregister_device);
902 
903 /**
904  *	parport_find_number - find a parallel port by number
905  *	@number: parallel port number
906  *
907  *	This returns the parallel port with the specified number, or
908  *	%NULL if there is none.
909  *
910  *	There is an implicit parport_get_port() done already; to throw
911  *	away the reference to the port that parport_find_number()
912  *	gives you, use parport_put_port().
913  */
914 
parport_find_number(int number)915 struct parport *parport_find_number(int number)
916 {
917 	struct parport *port, *result = NULL;
918 
919 	if (list_empty(&portlist))
920 		get_lowlevel_driver();
921 
922 	spin_lock(&parportlist_lock);
923 	list_for_each_entry(port, &portlist, list) {
924 		if (port->number == number) {
925 			result = parport_get_port(port);
926 			break;
927 		}
928 	}
929 	spin_unlock(&parportlist_lock);
930 	return result;
931 }
932 EXPORT_SYMBOL(parport_find_number);
933 
934 /**
935  *	parport_find_base - find a parallel port by base address
936  *	@base: base I/O address
937  *
938  *	This returns the parallel port with the specified base
939  *	address, or %NULL if there is none.
940  *
941  *	There is an implicit parport_get_port() done already; to throw
942  *	away the reference to the port that parport_find_base()
943  *	gives you, use parport_put_port().
944  */
945 
parport_find_base(unsigned long base)946 struct parport *parport_find_base(unsigned long base)
947 {
948 	struct parport *port, *result = NULL;
949 
950 	if (list_empty(&portlist))
951 		get_lowlevel_driver();
952 
953 	spin_lock(&parportlist_lock);
954 	list_for_each_entry(port, &portlist, list) {
955 		if (port->base == base) {
956 			result = parport_get_port(port);
957 			break;
958 		}
959 	}
960 	spin_unlock(&parportlist_lock);
961 	return result;
962 }
963 EXPORT_SYMBOL(parport_find_base);
964 
965 /**
966  *	parport_claim - claim access to a parallel port device
967  *	@dev: pointer to structure representing a device on the port
968  *
969  *	This function will not block and so can be used from interrupt
970  *	context.  If parport_claim() succeeds in claiming access to
971  *	the port it returns zero and the port is available to use.  It
972  *	may fail (returning non-zero) if the port is in use by another
973  *	driver and that driver is not willing to relinquish control of
974  *	the port.
975  **/
976 
parport_claim(struct pardevice * dev)977 int parport_claim(struct pardevice *dev)
978 {
979 	struct pardevice *oldcad;
980 	struct parport *port = dev->port->physport;
981 	unsigned long flags;
982 
983 	if (port->cad == dev) {
984 		pr_info("%s: %s already owner\n", dev->port->name, dev->name);
985 		return 0;
986 	}
987 
988 	/* Preempt any current device */
989 	write_lock_irqsave(&port->cad_lock, flags);
990 	oldcad = port->cad;
991 	if (oldcad) {
992 		if (oldcad->preempt) {
993 			if (oldcad->preempt(oldcad->private))
994 				goto blocked;
995 			port->ops->save_state(port, dev->state);
996 		} else
997 			goto blocked;
998 
999 		if (port->cad != oldcad) {
1000 			/*
1001 			 * I think we'll actually deadlock rather than
1002 			 * get here, but just in case..
1003 			 */
1004 			pr_warn("%s: %s released port when preempted!\n",
1005 				port->name, oldcad->name);
1006 			if (port->cad)
1007 				goto blocked;
1008 		}
1009 	}
1010 
1011 	/* Can't fail from now on, so mark ourselves as no longer waiting.  */
1012 	if (dev->waiting & 1) {
1013 		dev->waiting = 0;
1014 
1015 		/* Take ourselves out of the wait list again.  */
1016 		spin_lock_irq(&port->waitlist_lock);
1017 		if (dev->waitprev)
1018 			dev->waitprev->waitnext = dev->waitnext;
1019 		else
1020 			port->waithead = dev->waitnext;
1021 		if (dev->waitnext)
1022 			dev->waitnext->waitprev = dev->waitprev;
1023 		else
1024 			port->waittail = dev->waitprev;
1025 		spin_unlock_irq(&port->waitlist_lock);
1026 		dev->waitprev = dev->waitnext = NULL;
1027 	}
1028 
1029 	/* Now we do the change of devices */
1030 	port->cad = dev;
1031 
1032 #ifdef CONFIG_PARPORT_1284
1033 	/* If it's a mux port, select it. */
1034 	if (dev->port->muxport >= 0) {
1035 		/* FIXME */
1036 		port->muxsel = dev->port->muxport;
1037 	}
1038 
1039 	/* If it's a daisy chain device, select it. */
1040 	if (dev->daisy >= 0) {
1041 		/* This could be lazier. */
1042 		if (!parport_daisy_select(port, dev->daisy,
1043 					   IEEE1284_MODE_COMPAT))
1044 			port->daisy = dev->daisy;
1045 	}
1046 #endif /* IEEE1284.3 support */
1047 
1048 	/* Restore control registers */
1049 	port->ops->restore_state(port, dev->state);
1050 	write_unlock_irqrestore(&port->cad_lock, flags);
1051 	dev->time = jiffies;
1052 	return 0;
1053 
1054 blocked:
1055 	/*
1056 	 * If this is the first time we tried to claim the port, register an
1057 	 * interest.  This is only allowed for devices sleeping in
1058 	 * parport_claim_or_block(), or those with a wakeup function.
1059 	 */
1060 
1061 	/* The cad_lock is still held for writing here */
1062 	if (dev->waiting & 2 || dev->wakeup) {
1063 		spin_lock(&port->waitlist_lock);
1064 		if (test_and_set_bit(0, &dev->waiting) == 0) {
1065 			/* First add ourselves to the end of the wait list. */
1066 			dev->waitnext = NULL;
1067 			dev->waitprev = port->waittail;
1068 			if (port->waittail) {
1069 				port->waittail->waitnext = dev;
1070 				port->waittail = dev;
1071 			} else
1072 				port->waithead = port->waittail = dev;
1073 		}
1074 		spin_unlock(&port->waitlist_lock);
1075 	}
1076 	write_unlock_irqrestore(&port->cad_lock, flags);
1077 	return -EAGAIN;
1078 }
1079 EXPORT_SYMBOL(parport_claim);
1080 
1081 /**
1082  *	parport_claim_or_block - claim access to a parallel port device
1083  *	@dev: pointer to structure representing a device on the port
1084  *
1085  *	This behaves like parport_claim(), but will block if necessary
1086  *	to wait for the port to be free.  A return value of 1
1087  *	indicates that it slept; 0 means that it succeeded without
1088  *	needing to sleep.  A negative error code indicates failure.
1089  **/
1090 
parport_claim_or_block(struct pardevice * dev)1091 int parport_claim_or_block(struct pardevice *dev)
1092 {
1093 	int r;
1094 
1095 	/*
1096 	 * Signal to parport_claim() that we can wait even without a
1097 	 * wakeup function.
1098 	 */
1099 	dev->waiting = 2;
1100 
1101 	/* Try to claim the port.  If this fails, we need to sleep.  */
1102 	r = parport_claim(dev);
1103 	if (r == -EAGAIN) {
1104 #ifdef PARPORT_DEBUG_SHARING
1105 		printk(KERN_DEBUG "%s: parport_claim() returned -EAGAIN\n",
1106 		       dev->name);
1107 #endif
1108 		/*
1109 		 * FIXME!!! Use the proper locking for dev->waiting,
1110 		 * and make this use the "wait_event_interruptible()"
1111 		 * interfaces. The cli/sti that used to be here
1112 		 * did nothing.
1113 		 *
1114 		 * See also parport_release()
1115 		 */
1116 
1117 		/*
1118 		 * If dev->waiting is clear now, an interrupt
1119 		 * gave us the port and we would deadlock if we slept.
1120 		 */
1121 		if (dev->waiting) {
1122 			wait_event_interruptible(dev->wait_q,
1123 						 !dev->waiting);
1124 			if (signal_pending(current))
1125 				return -EINTR;
1126 			r = 1;
1127 		} else {
1128 			r = 0;
1129 #ifdef PARPORT_DEBUG_SHARING
1130 			printk(KERN_DEBUG "%s: didn't sleep in parport_claim_or_block()\n",
1131 			       dev->name);
1132 #endif
1133 		}
1134 
1135 #ifdef PARPORT_DEBUG_SHARING
1136 		if (dev->port->physport->cad != dev)
1137 			printk(KERN_DEBUG "%s: exiting parport_claim_or_block but %s owns port!\n",
1138 			       dev->name, dev->port->physport->cad ?
1139 			       dev->port->physport->cad->name : "nobody");
1140 #endif
1141 	}
1142 	dev->waiting = 0;
1143 	return r;
1144 }
1145 EXPORT_SYMBOL(parport_claim_or_block);
1146 
1147 /**
1148  *	parport_release - give up access to a parallel port device
1149  *	@dev: pointer to structure representing parallel port device
1150  *
1151  *	This function cannot fail, but it should not be called without
1152  *	the port claimed.  Similarly, if the port is already claimed
1153  *	you should not try claiming it again.
1154  **/
1155 
parport_release(struct pardevice * dev)1156 void parport_release(struct pardevice *dev)
1157 {
1158 	struct parport *port = dev->port->physport;
1159 	struct pardevice *pd;
1160 	unsigned long flags;
1161 
1162 	/* Make sure that dev is the current device */
1163 	write_lock_irqsave(&port->cad_lock, flags);
1164 	if (port->cad != dev) {
1165 		write_unlock_irqrestore(&port->cad_lock, flags);
1166 		pr_warn("%s: %s tried to release parport when not owner\n",
1167 			port->name, dev->name);
1168 		return;
1169 	}
1170 
1171 #ifdef CONFIG_PARPORT_1284
1172 	/* If this is on a mux port, deselect it. */
1173 	if (dev->port->muxport >= 0) {
1174 		/* FIXME */
1175 		port->muxsel = -1;
1176 	}
1177 
1178 	/* If this is a daisy device, deselect it. */
1179 	if (dev->daisy >= 0) {
1180 		parport_daisy_deselect_all(port);
1181 		port->daisy = -1;
1182 	}
1183 #endif
1184 
1185 	port->cad = NULL;
1186 	write_unlock_irqrestore(&port->cad_lock, flags);
1187 
1188 	/* Save control registers */
1189 	port->ops->save_state(port, dev->state);
1190 
1191 	/*
1192 	 * If anybody is waiting, find out who's been there longest and
1193 	 * then wake them up. (Note: no locking required)
1194 	 */
1195 	/* !!! LOCKING IS NEEDED HERE */
1196 	for (pd = port->waithead; pd; pd = pd->waitnext) {
1197 		if (pd->waiting & 2) { /* sleeping in claim_or_block */
1198 			parport_claim(pd);
1199 			if (waitqueue_active(&pd->wait_q))
1200 				wake_up_interruptible(&pd->wait_q);
1201 			return;
1202 		} else if (pd->wakeup) {
1203 			pd->wakeup(pd->private);
1204 			if (dev->port->cad) /* racy but no matter */
1205 				return;
1206 		} else {
1207 			pr_err("%s: don't know how to wake %s\n",
1208 			       port->name, pd->name);
1209 		}
1210 	}
1211 
1212 	/*
1213 	 * Nobody was waiting, so walk the list to see if anyone is
1214 	 * interested in being woken up. (Note: no locking required)
1215 	 */
1216 	/* !!! LOCKING IS NEEDED HERE */
1217 	for (pd = port->devices; !port->cad && pd; pd = pd->next) {
1218 		if (pd->wakeup && pd != dev)
1219 			pd->wakeup(pd->private);
1220 	}
1221 }
1222 EXPORT_SYMBOL(parport_release);
1223 
parport_irq_handler(int irq,void * dev_id)1224 irqreturn_t parport_irq_handler(int irq, void *dev_id)
1225 {
1226 	struct parport *port = dev_id;
1227 
1228 	parport_generic_irq(port);
1229 
1230 	return IRQ_HANDLED;
1231 }
1232 EXPORT_SYMBOL(parport_irq_handler);
1233 
1234 MODULE_LICENSE("GPL");
1235