LXR linux/drivers/block/paride/pseudo.h

   1/* 
   2        pseudo.h    (c) 1997-8  Grant R. Guenther <grant@torque.net>
   3                                Under the terms of the GNU General Public License.
   4
   5        This is the "pseudo-interrupt" logic for parallel port drivers.
   6
   7        This module is #included into each driver.  It makes one
   8        function available:
   9
  10                ps_set_intr( void (*continuation)(void),
  11                             int  (*ready)(void),
  12                             int timeout,
  13                             int nice )
  14
  15        Which will arrange for ready() to be evaluated frequently and
  16        when either it returns true, or timeout jiffies have passed,
  17        continuation() will be invoked.
  18
  19        If nice is 1, the test will done approximately once a
  20        jiffy.  If nice is 0, the test will also be done whenever
  21        the scheduler runs (by adding it to a task queue).  If
  22        nice is greater than 1, the test will be done once every
  23        (nice-1) jiffies. 
  24
  25*/
  26
  27/* Changes:
  28
  29        1.01    1998.05.03      Switched from cli()/sti() to spinlocks
  30        1.02    1998.12.14      Added support for nice > 1
  31*/
  32        
  33#define PS_VERSION      "1.02"
  34
  35#include <linux/sched.h>
  36#include <linux/workqueue.h>
  37
  38static void ps_tq_int(struct work_struct *work);
  39
  40static void (* ps_continuation)(void);
  41static int (* ps_ready)(void);
  42static unsigned long ps_timeout;
  43static int ps_tq_active = 0;
  44static int ps_nice = 0;
  45
  46static DEFINE_SPINLOCK(ps_spinlock __attribute__((unused)));
  47
  48static DECLARE_DELAYED_WORK(ps_tq, ps_tq_int);
  49
  50static void ps_set_intr(void (*continuation)(void), 
  51                        int (*ready)(void),
  52                        int timeout, int nice)
  53{
  54        unsigned long   flags;
  55
  56        spin_lock_irqsave(&ps_spinlock,flags);
  57
  58        ps_continuation = continuation;
  59        ps_ready = ready;
  60        ps_timeout = jiffies + timeout;
  61        ps_nice = nice;
  62
  63        if (!ps_tq_active) {
  64                ps_tq_active = 1;
  65                if (!ps_nice)
  66                        schedule_delayed_work(&ps_tq, 0);
  67                else
  68                        schedule_delayed_work(&ps_tq, ps_nice-1);
  69        }
  70        spin_unlock_irqrestore(&ps_spinlock,flags);
  71}
  72
  73static void ps_tq_int(struct work_struct *work)
  74{
  75        void (*con)(void);
  76        unsigned long flags;
  77
  78        spin_lock_irqsave(&ps_spinlock,flags);
  79
  80        con = ps_continuation;
  81        ps_tq_active = 0;
  82
  83        if (!con) {
  84                spin_unlock_irqrestore(&ps_spinlock,flags);
  85                return;
  86        }
  87        if (!ps_ready || ps_ready() || time_after_eq(jiffies, ps_timeout)) {
  88                ps_continuation = NULL;
  89                spin_unlock_irqrestore(&ps_spinlock,flags);
  90                con();
  91                return;
  92        }
  93        ps_tq_active = 1;
  94        if (!ps_nice)
  95                schedule_delayed_work(&ps_tq, 0);
  96        else
  97                schedule_delayed_work(&ps_tq, ps_nice-1);
  98        spin_unlock_irqrestore(&ps_spinlock,flags);
  99}
 100
 101/* end of pseudo.h */
 102
 103