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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/drivers/block/paride/pseudo.h
15112 views
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/* 

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        pseudo.h    (c) 1997-8  Grant R. Guenther <[email protected]>

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                                Under the terms of the GNU General Public License.

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	This is the "pseudo-interrupt" logic for parallel port drivers.

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        This module is #included into each driver.  It makes one

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        function available:

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		ps_set_intr( void (*continuation)(void),

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			     int  (*ready)(void),

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			     int timeout,

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			     int nice )

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	Which will arrange for ready() to be evaluated frequently and

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	when either it returns true, or timeout jiffies have passed,

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	continuation() will be invoked.

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	If nice is 1, the test will done approximately once a

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	jiffy.  If nice is 0, the test will also be done whenever

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	the scheduler runs (by adding it to a task queue).  If

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	nice is greater than 1, the test will be done once every

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	(nice-1) jiffies. 

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*/

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/* Changes:

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	1.01	1998.05.03	Switched from cli()/sti() to spinlocks

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	1.02    1998.12.14      Added support for nice > 1

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*/

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#define PS_VERSION	"1.02"

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#include <linux/sched.h>

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#include <linux/workqueue.h>

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static void ps_tq_int(struct work_struct *work);

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static void (* ps_continuation)(void);

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static int (* ps_ready)(void);

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static unsigned long ps_timeout;

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static int ps_tq_active = 0;

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static int ps_nice = 0;

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static DEFINE_SPINLOCK(ps_spinlock __attribute__((unused)));

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static DECLARE_DELAYED_WORK(ps_tq, ps_tq_int);

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static void ps_set_intr(void (*continuation)(void), 

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			int (*ready)(void),

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			int timeout, int nice)

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{

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	unsigned long	flags;

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	spin_lock_irqsave(&ps_spinlock,flags);

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	ps_continuation = continuation;

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	ps_ready = ready;

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	ps_timeout = jiffies + timeout;

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	ps_nice = nice;

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	if (!ps_tq_active) {

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		ps_tq_active = 1;

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		if (!ps_nice)

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			schedule_delayed_work(&ps_tq, 0);

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		else

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			schedule_delayed_work(&ps_tq, ps_nice-1);

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	}

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	spin_unlock_irqrestore(&ps_spinlock,flags);

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}

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static void ps_tq_int(struct work_struct *work)

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{

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	void (*con)(void);

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	unsigned long flags;

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	spin_lock_irqsave(&ps_spinlock,flags);

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	con = ps_continuation;

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	ps_tq_active = 0;

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	if (!con) {

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		spin_unlock_irqrestore(&ps_spinlock,flags);

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		return;

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	}

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	if (!ps_ready || ps_ready() || time_after_eq(jiffies, ps_timeout)) {

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		ps_continuation = NULL;

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		spin_unlock_irqrestore(&ps_spinlock,flags);

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		con();

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		return;

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	}

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	ps_tq_active = 1;

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	if (!ps_nice)

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		schedule_delayed_work(&ps_tq, 0);

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	else

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		schedule_delayed_work(&ps_tq, ps_nice-1);

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	spin_unlock_irqrestore(&ps_spinlock,flags);

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}

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/* end of pseudo.h */

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