share.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,016 行 · 第 1/2 页

/* $Id: parport_share.c,v 1.15 1998/01/11 12:06:17 philip Exp $
 * Parallel-port resource manager code.
 * 
 * Authors: David Campbell <[e-mail]>
 *          Tim Waugh <[e-mail]>
 *          Jose Renau <[e-mail]>
 *          Philip Blundell <[e-mail]>
 *	    Andrea Arcangeli
 *
 * based on work by Grant Guenther <[e-mail]>
 *          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/config.h>
#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 <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 spinlock_t parportlist_lock = SPIN_LOCK_UNLOCKED;

/* list of all allocated ports, sorted by ->number */
static LIST_HEAD(all_ports);
static spinlock_t full_list_lock = SPIN_LOCK_UNLOCKED;

static LIST_HEAD(drivers);

static DECLARE_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 ();

	down(&registration_lock);
	list_for_each_entry(port, &portlist, list)
		drv->attach(port);
	list_add(&drv->list, &drivers);
	up(&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;

	down(&registration_lock);
	list_del_init(&drv->list);
	list_for_each_entry(port, &portlist, list)
		drv->detach(port);
	up(&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++) {
		if (port->probe_info[d].class_name)
			kfree (port->probe_info[d].class_name);
		if (port->probe_info[d].mfr)
			kfree (port->probe_info[d].mfr);
		if (port->probe_info[d].model)
			kfree (port->probe_info[d].model);
		if (port->probe_info[d].cmdset)
			kfree (port->probe_info[d].cmdset);
		if (port->probe_info[d].description)
			kfree (port->probe_info[d].description);
	}

	kfree(port->name);
	kfree(port);
}

/**
 *	parport_get_port - increment a port's reference count
 *	@port: the port
 *
 *	This ensure's 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));
	tmp->cad_lock = RW_LOCK_UNLOCKED;
	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);
	down(&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);
	}
	up(&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;

	down(&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);

	up(&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