kernel-ark/drivers/parport/share.c
David Howells 7d12e780e0 IRQ: Maintain regs pointer globally rather than passing to IRQ handlers
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.

The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around.  On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).

Where appropriate, an arch may override the generic storage facility and do
something different with the variable.  On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.

Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions.  Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller.  A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.

I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.

This will affect all archs.  Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:

	struct pt_regs *old_regs = set_irq_regs(regs);

And put the old one back at the end:

	set_irq_regs(old_regs);

Don't pass regs through to generic_handle_irq() or __do_IRQ().

In timer_interrupt(), this sort of change will be necessary:

	-	update_process_times(user_mode(regs));
	-	profile_tick(CPU_PROFILING, regs);
	+	update_process_times(user_mode(get_irq_regs()));
	+	profile_tick(CPU_PROFILING);

I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().

Some notes on the interrupt handling in the drivers:

 (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
     the input_dev struct.

 (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
     something different depending on whether it's been supplied with a regs
     pointer or not.

 (*) Various IRQ handler function pointers have been moved to type
     irq_handler_t.

Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 15:10:12 +01:00

1011 lines
29 KiB
C

/* $Id: parport_share.c,v 1.15 1998/01/11 12:06:17 philip Exp $
* Parallel-port resource manager code.
*
* Authors: David Campbell <campbell@tirian.che.curtin.edu.au>
* Tim Waugh <tim@cyberelk.demon.co.uk>
* Jose Renau <renau@acm.org>
* Philip Blundell <philb@gnu.org>
* Andrea Arcangeli
*
* based on work by Grant Guenther <grant@torque.net>
* and Philip Blundell
*
* Any part of this program may be used in documents licensed under
* the GNU Free Documentation License, Version 1.1 or any later version
* published by the Free Software Foundation.
*/
#undef PARPORT_DEBUG_SHARING /* undef for production */
#include <linux/module.h>
#include <linux/string.h>
#include <linux/threads.h>
#include <linux/parport.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <asm/irq.h>
#undef PARPORT_PARANOID
#define PARPORT_DEFAULT_TIMESLICE (HZ/5)
unsigned long parport_default_timeslice = PARPORT_DEFAULT_TIMESLICE;
int parport_default_spintime = DEFAULT_SPIN_TIME;
static LIST_HEAD(portlist);
static DEFINE_SPINLOCK(parportlist_lock);
/* list of all allocated ports, sorted by ->number */
static LIST_HEAD(all_ports);
static DEFINE_SPINLOCK(full_list_lock);
static LIST_HEAD(drivers);
static DEFINE_MUTEX(registration_lock);
/* What you can do to a port that's gone away.. */
static void dead_write_lines (struct parport *p, unsigned char b){}
static unsigned char dead_read_lines (struct parport *p) { return 0; }
static unsigned char dead_frob_lines (struct parport *p, unsigned char b,
unsigned char c) { return 0; }
static void dead_onearg (struct parport *p){}
static void dead_initstate (struct pardevice *d, struct parport_state *s) { }
static void dead_state (struct parport *p, struct parport_state *s) { }
static size_t dead_write (struct parport *p, const void *b, size_t l, int f)
{ return 0; }
static size_t dead_read (struct parport *p, void *b, size_t l, int f)
{ return 0; }
static struct parport_operations dead_ops = {
.write_data = dead_write_lines, /* data */
.read_data = dead_read_lines,
.write_control = dead_write_lines, /* control */
.read_control = dead_read_lines,
.frob_control = dead_frob_lines,
.read_status = dead_read_lines, /* status */
.enable_irq = dead_onearg, /* enable_irq */
.disable_irq = dead_onearg, /* disable_irq */
.data_forward = dead_onearg, /* data_forward */
.data_reverse = dead_onearg, /* data_reverse */
.init_state = dead_initstate, /* init_state */
.save_state = dead_state,
.restore_state = dead_state,
.epp_write_data = dead_write, /* epp */
.epp_read_data = dead_read,
.epp_write_addr = dead_write,
.epp_read_addr = dead_read,
.ecp_write_data = dead_write, /* ecp */
.ecp_read_data = dead_read,
.ecp_write_addr = dead_write,
.compat_write_data = dead_write, /* compat */
.nibble_read_data = dead_read, /* nibble */
.byte_read_data = dead_read, /* byte */
.owner = NULL,
};
/* Call attach(port) for each registered driver. */
static void attach_driver_chain(struct parport *port)
{
/* caller has exclusive registration_lock */
struct parport_driver *drv;
list_for_each_entry(drv, &drivers, list)
drv->attach(port);
}
/* Call detach(port) for each registered driver. */
static void detach_driver_chain(struct parport *port)
{
struct parport_driver *drv;
/* caller has exclusive registration_lock */
list_for_each_entry(drv, &drivers, list)
drv->detach (port);
}
/* Ask kmod for some lowlevel drivers. */
static void get_lowlevel_driver (void)
{
/* There is no actual module called this: you should set
* up an alias for modutils. */
request_module ("parport_lowlevel");
}
/**
* parport_register_driver - register a parallel port device driver
* @drv: structure describing the driver
*
* This can be called by a parallel port device driver in order
* to receive notifications about ports being found in the
* system, as well as ports no longer available.
*
* The @drv structure is allocated by the caller and must not be
* deallocated until after calling parport_unregister_driver().
*
* The driver's attach() function may block. The port that
* attach() is given will be valid for the duration of the
* callback, but if the driver wants to take a copy of the
* pointer it must call parport_get_port() to do so. Calling
* parport_register_device() on that port will do this for you.
*
* The driver's detach() function may block. The port that
* detach() is given will be valid for the duration of the
* callback, but if the driver wants to take a copy of the
* pointer it must call parport_get_port() to do so.
*
* Returns 0 on success. Currently it always succeeds.
**/
int parport_register_driver (struct parport_driver *drv)
{
struct parport *port;
if (list_empty(&portlist))
get_lowlevel_driver ();
mutex_lock(&registration_lock);
list_for_each_entry(port, &portlist, list)
drv->attach(port);
list_add(&drv->list, &drivers);
mutex_unlock(&registration_lock);
return 0;
}
/**
* parport_unregister_driver - deregister a parallel port device driver
* @drv: structure describing the driver that was given to
* parport_register_driver()
*
* This should be called by a parallel port device driver that
* has registered itself using parport_register_driver() when it
* is about to be unloaded.
*
* When it returns, the driver's attach() routine will no longer
* be called, and for each port that attach() was called for, the
* detach() routine will have been called.
*
* All the driver's attach() and detach() calls are guaranteed to have
* finished by the time this function returns.
**/
void parport_unregister_driver (struct parport_driver *drv)
{
struct parport *port;
mutex_lock(&registration_lock);
list_del_init(&drv->list);
list_for_each_entry(port, &portlist, list)
drv->detach(port);
mutex_unlock(&registration_lock);
}
static void free_port (struct parport *port)
{
int d;
spin_lock(&full_list_lock);
list_del(&port->full_list);
spin_unlock(&full_list_lock);
for (d = 0; d < 5; d++) {
kfree(port->probe_info[d].class_name);
kfree(port->probe_info[d].mfr);
kfree(port->probe_info[d].model);
kfree(port->probe_info[d].cmdset);
kfree(port->probe_info[d].description);
}
kfree(port->name);
kfree(port);
}
/**
* parport_get_port - increment a port's reference count
* @port: the port
*
* This ensures that a struct parport pointer remains valid
* until the matching parport_put_port() call.
**/
struct parport *parport_get_port (struct parport *port)
{
atomic_inc (&port->ref_count);
return port;
}
/**
* parport_put_port - decrement a port's reference count
* @port: the port
*
* This should be called once for each call to parport_get_port(),
* once the port is no longer needed.
**/
void parport_put_port (struct parport *port)
{
if (atomic_dec_and_test (&port->ref_count))
/* Can destroy it now. */
free_port (port);
return;
}
/**
* parport_register_port - register a parallel port
* @base: base I/O address
* @irq: IRQ line
* @dma: DMA channel
* @ops: pointer to the port driver's port operations structure
*
* When a parallel port (lowlevel) driver finds a port that
* should be made available to parallel port device drivers, it
* should call parport_register_port(). The @base, @irq, and
* @dma parameters are for the convenience of port drivers, and
* for ports where they aren't meaningful needn't be set to
* anything special. They can be altered afterwards by adjusting
* the relevant members of the parport structure that is returned
* and represents the port. They should not be tampered with
* after calling parport_announce_port, however.
*
* If there are parallel port device drivers in the system that
* have registered themselves using parport_register_driver(),
* they are not told about the port at this time; that is done by
* parport_announce_port().
*
* The @ops structure is allocated by the caller, and must not be
* deallocated before calling parport_remove_port().
*
* If there is no memory to allocate a new parport structure,
* this function will return %NULL.
**/
struct parport *parport_register_port(unsigned long base, int irq, int dma,
struct parport_operations *ops)
{
struct list_head *l;
struct parport *tmp;
int num;
int device;
char *name;
tmp = kmalloc(sizeof(struct parport), GFP_KERNEL);
if (!tmp) {
printk(KERN_WARNING "parport: memory squeeze\n");
return NULL;
}
/* Init our structure */
memset(tmp, 0, sizeof(struct parport));
tmp->base = base;
tmp->irq = irq;
tmp->dma = dma;
tmp->muxport = tmp->daisy = tmp->muxsel = -1;
tmp->modes = 0;
INIT_LIST_HEAD(&tmp->list);
tmp->devices = tmp->cad = NULL;
tmp->flags = 0;
tmp->ops = ops;
tmp->physport = tmp;
memset (tmp->probe_info, 0, 5 * sizeof (struct parport_device_info));
rwlock_init(&tmp->cad_lock);
spin_lock_init(&tmp->waitlist_lock);
spin_lock_init(&tmp->pardevice_lock);
tmp->ieee1284.mode = IEEE1284_MODE_COMPAT;
tmp->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
init_MUTEX_LOCKED (&tmp->ieee1284.irq); /* actually a semaphore at 0 */
tmp->spintime = parport_default_spintime;
atomic_set (&tmp->ref_count, 1);
INIT_LIST_HEAD(&tmp->full_list);
name = kmalloc(15, GFP_KERNEL);
if (!name) {
printk(KERN_ERR "parport: memory squeeze\n");
kfree(tmp);
return NULL;
}
/* Search for the lowest free parport number. */
spin_lock(&full_list_lock);
for (l = all_ports.next, num = 0; l != &all_ports; l = l->next, num++) {
struct parport *p = list_entry(l, struct parport, full_list);
if (p->number != num)
break;
}
tmp->portnum = tmp->number = num;
list_add_tail(&tmp->full_list, l);
spin_unlock(&full_list_lock);
/*
* Now that the portnum is known finish doing the Init.
*/
sprintf(name, "parport%d", tmp->portnum = tmp->number);
tmp->name = name;
for (device = 0; device < 5; device++)
/* assume the worst */
tmp->probe_info[device].class = PARPORT_CLASS_LEGACY;
tmp->waithead = tmp->waittail = NULL;
return tmp;
}
/**
* parport_announce_port - tell device drivers about a parallel port
* @port: parallel port to announce
*
* After a port driver has registered a parallel port with
* parport_register_port, and performed any necessary
* initialisation or adjustments, it should call
* parport_announce_port() in order to notify all device drivers
* that have called parport_register_driver(). Their attach()
* functions will be called, with @port as the parameter.
**/
void parport_announce_port (struct parport *port)
{
int i;
#ifdef CONFIG_PARPORT_1284
/* Analyse the IEEE1284.3 topology of the port. */
parport_daisy_init(port);
#endif
parport_proc_register(port);
mutex_lock(&registration_lock);
spin_lock_irq(&parportlist_lock);
list_add_tail(&port->list, &portlist);
for (i = 1; i < 3; i++) {
struct parport *slave = port->slaves[i-1];
if (slave)
list_add_tail(&slave->list, &portlist);
}
spin_unlock_irq(&parportlist_lock);
/* Let drivers know that new port(s) has arrived. */
attach_driver_chain (port);
for (i = 1; i < 3; i++) {
struct parport *slave = port->slaves[i-1];
if (slave)
attach_driver_chain(slave);
}
mutex_unlock(&registration_lock);
}
/**
* parport_remove_port - deregister a parallel port
* @port: parallel port to deregister
*
* When a parallel port driver is forcibly unloaded, or a
* parallel port becomes inaccessible, the port driver must call
* this function in order to deal with device drivers that still
* want to use it.
*
* The parport structure associated with the port has its
* operations structure replaced with one containing 'null'
* operations that return errors or just don't do anything.
*
* Any drivers that have registered themselves using
* parport_register_driver() are notified that the port is no
* longer accessible by having their detach() routines called
* with @port as the parameter.
**/
void parport_remove_port(struct parport *port)
{
int i;
mutex_lock(&registration_lock);
/* Spread the word. */
detach_driver_chain (port);
#ifdef CONFIG_PARPORT_1284
/* Forget the IEEE1284.3 topology of the port. */
parport_daisy_fini(port);
for (i = 1; i < 3; i++) {
struct parport *slave = port->slaves[i-1];
if (!slave)
continue;
detach_driver_chain(slave);
parport_daisy_fini(slave);
}
#endif
port->ops = &dead_ops;
spin_lock(&parportlist_lock);
list_del_init(&port->list);
for (i = 1; i < 3; i++) {
struct parport *slave = port->slaves[i-1];
if (slave)
list_del_init(&slave->list);
}
spin_unlock(&parportlist_lock);
mutex_unlock(&registration_lock);
parport_proc_unregister(port);
for (i = 1; i < 3; i++) {
struct parport *slave = port->slaves[i-1];
if (slave)
parport_put_port(slave);
}
}
/**
* parport_register_device - register a device on a parallel port
* @port: port to which the device is attached
* @name: a name to refer to the device
* @pf: preemption callback
* @kf: kick callback (wake-up)
* @irq_func: interrupt handler
* @flags: registration flags
* @handle: data for callback functions
*
* This function, called by parallel port device drivers,
* declares that a device is connected to a port, and tells the
* system all it needs to know.
*
* The @name is allocated by the caller and must not be
* deallocated until the caller calls @parport_unregister_device
* for that device.
*
* The preemption callback function, @pf, is called when this
* device driver has claimed access to the port but another
* device driver wants to use it. It is given @handle as its
* parameter, and should return zero if it is willing for the
* system to release the port to another driver on its behalf.
* If it wants to keep control of the port it should return
* non-zero, and no action will be taken. It is good manners for
* the driver to try to release the port at the earliest
* opportunity after its preemption callback rejects a preemption
* attempt. Note that if a preemption callback is happy for
* preemption to go ahead, there is no need to release the port;
* it is done automatically. This function may not block, as it
* may be called from interrupt context. If the device driver
* does not support preemption, @pf can be %NULL.
*
* The wake-up ("kick") callback function, @kf, is called when
* the port is available to be claimed for exclusive access; that
* is, parport_claim() is guaranteed to succeed when called from
* inside the wake-up callback function. If the driver wants to
* claim the port it should do so; otherwise, it need not take
* any action. This function may not block, as it may be called
* from interrupt context. If the device driver does not want to
* be explicitly invited to claim the port in this way, @kf can
* be %NULL.
*
* The interrupt handler, @irq_func, is called when an interrupt
* arrives from the parallel port. Note that if a device driver
* wants to use interrupts it should use parport_enable_irq(),
* and can also check the irq member of the parport structure
* representing the port.
*
* The parallel port (lowlevel) driver is the one that has called
* request_irq() and whose interrupt handler is called first.
* This handler does whatever needs to be done to the hardware to
* acknowledge the interrupt (for PC-style ports there is nothing
* special to be done). It then tells the IEEE 1284 code about
* the interrupt, which may involve reacting to an IEEE 1284
* event depending on the current IEEE 1284 phase. After this,
* it calls @irq_func. Needless to say, @irq_func will be called
* from interrupt context, and may not block.
*
* The %PARPORT_DEV_EXCL flag is for preventing port sharing, and
* so should only be used when sharing the port with other device
* drivers is impossible and would lead to incorrect behaviour.
* Use it sparingly! Normally, @flags will be zero.
*
* This function returns a pointer to a structure that represents
* the device on the port, or %NULL if there is not enough memory
* to allocate space for that structure.
**/
struct pardevice *
parport_register_device(struct parport *port, const char *name,
int (*pf)(void *), void (*kf)(void *),
void (*irq_func)(int, void *),
int flags, void *handle)
{
struct pardevice *tmp;
if (port->physport->flags & PARPORT_FLAG_EXCL) {
/* An exclusive device is registered. */
printk (KERN_DEBUG "%s: no more devices allowed\n",
port->name);
return NULL;
}
if (flags & PARPORT_DEV_LURK) {
if (!pf || !kf) {
printk(KERN_INFO "%s: refused to register lurking device (%s) without callbacks\n", port->name, name);
return NULL;
}
}
/* We up our own module reference count, and that of the port
on which a device is to be registered, to ensure that
neither of us gets unloaded while we sleep in (e.g.)
kmalloc.
*/
if (!try_module_get(port->ops->owner)) {
return NULL;
}
parport_get_port (port);
tmp = kmalloc(sizeof(struct pardevice), GFP_KERNEL);
if (tmp == NULL) {
printk(KERN_WARNING "%s: memory squeeze, couldn't register %s.\n", port->name, name);
goto out;
}
tmp->state = kmalloc(sizeof(struct parport_state), GFP_KERNEL);
if (tmp->state == NULL) {
printk(KERN_WARNING "%s: memory squeeze, couldn't register %s.\n", port->name, name);
goto out_free_pardevice;
}
tmp->name = name;
tmp->port = port;
tmp->daisy = -1;
tmp->preempt = pf;
tmp->wakeup = kf;
tmp->private = handle;
tmp->flags = flags;
tmp->irq_func = irq_func;
tmp->waiting = 0;
tmp->timeout = 5 * HZ;
/* Chain this onto the list */
tmp->prev = NULL;
/*
* This function must not run from an irq handler so we don' t need
* to clear irq on the local CPU. -arca
*/
spin_lock(&port->physport->pardevice_lock);
if (flags & PARPORT_DEV_EXCL) {
if (port->physport->devices) {
spin_unlock (&port->physport->pardevice_lock);
printk (KERN_DEBUG
"%s: cannot grant exclusive access for "
"device %s\n", port->name, name);
goto out_free_all;
}
port->flags |= PARPORT_FLAG_EXCL;
}
tmp->next = port->physport->devices;
wmb(); /* Make sure that tmp->next is written before it's
added to the list; see comments marked 'no locking
required' */
if (port->physport->devices)
port->physport->devices->prev = tmp;
port->physport->devices = tmp;
spin_unlock(&port->physport->pardevice_lock);
init_waitqueue_head(&tmp->wait_q);
tmp->timeslice = parport_default_timeslice;
tmp->waitnext = tmp->waitprev = NULL;
/*
* This has to be run as last thing since init_state may need other
* pardevice fields. -arca
*/
port->ops->init_state(tmp, tmp->state);
parport_device_proc_register(tmp);
return tmp;
out_free_all:
kfree(tmp->state);
out_free_pardevice:
kfree(tmp);
out:
parport_put_port (port);
module_put(port->ops->owner);
return NULL;
}
/**
* parport_unregister_device - deregister a device on a parallel port
* @dev: pointer to structure representing device
*
* This undoes the effect of parport_register_device().
**/
void parport_unregister_device(struct pardevice *dev)
{
struct parport *port;
#ifdef PARPORT_PARANOID
if (dev == NULL) {
printk(KERN_ERR "parport_unregister_device: passed NULL\n");
return;
}
#endif
parport_device_proc_unregister(dev);
port = dev->port->physport;
if (port->cad == dev) {
printk(KERN_DEBUG "%s: %s forgot to release port\n",
port->name, dev->name);
parport_release (dev);
}
spin_lock(&port->pardevice_lock);
if (dev->next)
dev->next->prev = dev->prev;
if (dev->prev)
dev->prev->next = dev->next;
else
port->devices = dev->next;
if (dev->flags & PARPORT_DEV_EXCL)
port->flags &= ~PARPORT_FLAG_EXCL;
spin_unlock(&port->pardevice_lock);
/* Make sure we haven't left any pointers around in the wait
* list. */
spin_lock (&port->waitlist_lock);
if (dev->waitprev || dev->waitnext || port->waithead == dev) {
if (dev->waitprev)
dev->waitprev->waitnext = dev->waitnext;
else
port->waithead = dev->waitnext;
if (dev->waitnext)
dev->waitnext->waitprev = dev->waitprev;
else
port->waittail = dev->waitprev;
}
spin_unlock (&port->waitlist_lock);
kfree(dev->state);
kfree(dev);
module_put(port->ops->owner);
parport_put_port (port);
}
/**
* parport_find_number - find a parallel port by number
* @number: parallel port number
*
* This returns the parallel port with the specified number, or
* %NULL if there is none.
*
* There is an implicit parport_get_port() done already; to throw
* away the reference to the port that parport_find_number()
* gives you, use parport_put_port().
*/
struct parport *parport_find_number (int number)
{
struct parport *port, *result = NULL;
if (list_empty(&portlist))
get_lowlevel_driver ();
spin_lock (&parportlist_lock);
list_for_each_entry(port, &portlist, list) {
if (port->number == number) {
result = parport_get_port (port);
break;
}
}
spin_unlock (&parportlist_lock);
return result;
}
/**
* parport_find_base - find a parallel port by base address
* @base: base I/O address
*
* This returns the parallel port with the specified base
* address, or %NULL if there is none.
*
* There is an implicit parport_get_port() done already; to throw
* away the reference to the port that parport_find_base()
* gives you, use parport_put_port().
*/
struct parport *parport_find_base (unsigned long base)
{
struct parport *port, *result = NULL;
if (list_empty(&portlist))
get_lowlevel_driver ();
spin_lock (&parportlist_lock);
list_for_each_entry(port, &portlist, list) {
if (port->base == base) {
result = parport_get_port (port);
break;
}
}
spin_unlock (&parportlist_lock);
return result;
}
/**
* parport_claim - claim access to a parallel port device
* @dev: pointer to structure representing a device on the port
*
* This function will not block and so can be used from interrupt
* context. If parport_claim() succeeds in claiming access to
* the port it returns zero and the port is available to use. It
* may fail (returning non-zero) if the port is in use by another
* driver and that driver is not willing to relinquish control of
* the port.
**/
int parport_claim(struct pardevice *dev)
{
struct pardevice *oldcad;
struct parport *port = dev->port->physport;
unsigned long flags;
if (port->cad == dev) {
printk(KERN_INFO "%s: %s already owner\n",
dev->port->name,dev->name);
return 0;
}
/* Preempt any current device */
write_lock_irqsave (&port->cad_lock, flags);
if ((oldcad = port->cad) != NULL) {
if (oldcad->preempt) {
if (oldcad->preempt(oldcad->private))
goto blocked;
port->ops->save_state(port, dev->state);
} else
goto blocked;
if (port->cad != oldcad) {
/* I think we'll actually deadlock rather than
get here, but just in case.. */
printk(KERN_WARNING
"%s: %s released port when preempted!\n",
port->name, oldcad->name);
if (port->cad)
goto blocked;
}
}
/* Can't fail from now on, so mark ourselves as no longer waiting. */
if (dev->waiting & 1) {
dev->waiting = 0;
/* Take ourselves out of the wait list again. */
spin_lock_irq (&port->waitlist_lock);
if (dev->waitprev)
dev->waitprev->waitnext = dev->waitnext;
else
port->waithead = dev->waitnext;
if (dev->waitnext)
dev->waitnext->waitprev = dev->waitprev;
else
port->waittail = dev->waitprev;
spin_unlock_irq (&port->waitlist_lock);
dev->waitprev = dev->waitnext = NULL;
}
/* Now we do the change of devices */
port->cad = dev;
#ifdef CONFIG_PARPORT_1284
/* If it's a mux port, select it. */
if (dev->port->muxport >= 0) {
/* FIXME */
port->muxsel = dev->port->muxport;
}
/* If it's a daisy chain device, select it. */
if (dev->daisy >= 0) {
/* This could be lazier. */
if (!parport_daisy_select (port, dev->daisy,
IEEE1284_MODE_COMPAT))
port->daisy = dev->daisy;
}
#endif /* IEEE1284.3 support */
/* Restore control registers */
port->ops->restore_state(port, dev->state);
write_unlock_irqrestore(&port->cad_lock, flags);
dev->time = jiffies;
return 0;
blocked:
/* If this is the first time we tried to claim the port, register an
interest. This is only allowed for devices sleeping in
parport_claim_or_block(), or those with a wakeup function. */
/* The cad_lock is still held for writing here */
if (dev->waiting & 2 || dev->wakeup) {
spin_lock (&port->waitlist_lock);
if (test_and_set_bit(0, &dev->waiting) == 0) {
/* First add ourselves to the end of the wait list. */
dev->waitnext = NULL;
dev->waitprev = port->waittail;
if (port->waittail) {
port->waittail->waitnext = dev;
port->waittail = dev;
} else
port->waithead = port->waittail = dev;
}
spin_unlock (&port->waitlist_lock);
}
write_unlock_irqrestore (&port->cad_lock, flags);
return -EAGAIN;
}
/**
* parport_claim_or_block - claim access to a parallel port device
* @dev: pointer to structure representing a device on the port
*
* This behaves like parport_claim(), but will block if necessary
* to wait for the port to be free. A return value of 1
* indicates that it slept; 0 means that it succeeded without
* needing to sleep. A negative error code indicates failure.
**/
int parport_claim_or_block(struct pardevice *dev)
{
int r;
/* Signal to parport_claim() that we can wait even without a
wakeup function. */
dev->waiting = 2;
/* Try to claim the port. If this fails, we need to sleep. */
r = parport_claim(dev);
if (r == -EAGAIN) {
#ifdef PARPORT_DEBUG_SHARING
printk(KERN_DEBUG "%s: parport_claim() returned -EAGAIN\n", dev->name);
#endif
/*
* FIXME!!! Use the proper locking for dev->waiting,
* and make this use the "wait_event_interruptible()"
* interfaces. The cli/sti that used to be here
* did nothing.
*
* See also parport_release()
*/
/* If dev->waiting is clear now, an interrupt
gave us the port and we would deadlock if we slept. */
if (dev->waiting) {
interruptible_sleep_on (&dev->wait_q);
if (signal_pending (current)) {
return -EINTR;
}
r = 1;
} else {
r = 0;
#ifdef PARPORT_DEBUG_SHARING
printk(KERN_DEBUG "%s: didn't sleep in parport_claim_or_block()\n",
dev->name);
#endif
}
#ifdef PARPORT_DEBUG_SHARING
if (dev->port->physport->cad != dev)
printk(KERN_DEBUG "%s: exiting parport_claim_or_block "
"but %s owns port!\n", dev->name,
dev->port->physport->cad ?
dev->port->physport->cad->name:"nobody");
#endif
}
dev->waiting = 0;
return r;
}
/**
* parport_release - give up access to a parallel port device
* @dev: pointer to structure representing parallel port device
*
* This function cannot fail, but it should not be called without
* the port claimed. Similarly, if the port is already claimed
* you should not try claiming it again.
**/
void parport_release(struct pardevice *dev)
{
struct parport *port = dev->port->physport;
struct pardevice *pd;
unsigned long flags;
/* Make sure that dev is the current device */
write_lock_irqsave(&port->cad_lock, flags);
if (port->cad != dev) {
write_unlock_irqrestore (&port->cad_lock, flags);
printk(KERN_WARNING "%s: %s tried to release parport "
"when not owner\n", port->name, dev->name);
return;
}
#ifdef CONFIG_PARPORT_1284
/* If this is on a mux port, deselect it. */
if (dev->port->muxport >= 0) {
/* FIXME */
port->muxsel = -1;
}
/* If this is a daisy device, deselect it. */
if (dev->daisy >= 0) {
parport_daisy_deselect_all (port);
port->daisy = -1;
}
#endif
port->cad = NULL;
write_unlock_irqrestore(&port->cad_lock, flags);
/* Save control registers */
port->ops->save_state(port, dev->state);
/* If anybody is waiting, find out who's been there longest and
then wake them up. (Note: no locking required) */
/* !!! LOCKING IS NEEDED HERE */
for (pd = port->waithead; pd; pd = pd->waitnext) {
if (pd->waiting & 2) { /* sleeping in claim_or_block */
parport_claim(pd);
if (waitqueue_active(&pd->wait_q))
wake_up_interruptible(&pd->wait_q);
return;
} else if (pd->wakeup) {
pd->wakeup(pd->private);
if (dev->port->cad) /* racy but no matter */
return;
} else {
printk(KERN_ERR "%s: don't know how to wake %s\n", port->name, pd->name);
}
}
/* Nobody was waiting, so walk the list to see if anyone is
interested in being woken up. (Note: no locking required) */
/* !!! LOCKING IS NEEDED HERE */
for (pd = port->devices; (port->cad == NULL) && pd; pd = pd->next) {
if (pd->wakeup && pd != dev)
pd->wakeup(pd->private);
}
}
/* Exported symbols for modules. */
EXPORT_SYMBOL(parport_claim);
EXPORT_SYMBOL(parport_claim_or_block);
EXPORT_SYMBOL(parport_release);
EXPORT_SYMBOL(parport_register_port);
EXPORT_SYMBOL(parport_announce_port);
EXPORT_SYMBOL(parport_remove_port);
EXPORT_SYMBOL(parport_register_driver);
EXPORT_SYMBOL(parport_unregister_driver);
EXPORT_SYMBOL(parport_register_device);
EXPORT_SYMBOL(parport_unregister_device);
EXPORT_SYMBOL(parport_get_port);
EXPORT_SYMBOL(parport_put_port);
EXPORT_SYMBOL(parport_find_number);
EXPORT_SYMBOL(parport_find_base);
MODULE_LICENSE("GPL");