| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
| 38 | static void ps_tq_int( void *data); |
| 39 | |
| 40 | static void (* ps_continuation)(void); |
| 41 | static int (* ps_ready)(void); |
| 42 | static unsigned long ps_timeout; |
| 43 | static int ps_tq_active = 0; |
| 44 | static int ps_nice = 0; |
| 45 | |
| 46 | static DEFINE_SPINLOCK(ps_spinlock __attribute__((unused))); |
| 47 | |
| 48 | static DECLARE_WORK(ps_tq, ps_tq_int, NULL); |
| 49 | |
| 50 | static 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_work(&ps_tq); |
| 67 | else |
| 68 | schedule_delayed_work(&ps_tq, ps_nice-1); |
| 69 | } |
| 70 | spin_unlock_irqrestore(&ps_spinlock,flags); |
| 71 | } |
| 72 | |
| 73 | static void ps_tq_int(void *data) |
| 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_work(&ps_tq); |
| 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 | |