| 1 | /* PM watchdog timer management. These functions in this file provide
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| 2 | * a convenient interface to the timers library that manages a list of
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| 3 | * watchdog timers. All details of scheduling an alarm at the CLOCK task
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| 4 | * are hidden behind this interface.
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| 5 | * Only system processes are allowed to set an alarm timer at the kernel.
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| 6 | * Therefore, the PM maintains a local list of timers for user processes
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| 7 | * that requested an alarm signal.
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| 8 | *
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| 9 | * The entry points into this file are:
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| 10 | * pm_set_timer: reset and existing or set a new watchdog timer
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| 11 | * pm_expire_timers: check for expired timers and run watchdog functions
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| 12 | * pm_cancel_timer: remove a time from the list of timers
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| 13 | *
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| 14 | */
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| 15 |
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| 16 | #include "pm.h"
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| 17 |
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| 18 | #include <timers.h>
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| 19 | #include <minix/syslib.h>
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| 20 | #include <minix/com.h>
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| 21 |
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| 22 | PRIVATE timer_t *pm_timers = NULL;
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| 23 |
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| 24 | /*===========================================================================*
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| 25 | * pm_set_timer *
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| 26 | *===========================================================================*/
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| 27 | PUBLIC void pm_set_timer(timer_t *tp, int ticks, tmr_func_t watchdog, int arg)
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| 28 | {
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| 29 | int r;
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| 30 | clock_t now, prev_time = 0, next_time;
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| 31 |
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| 32 | if ((r = getuptime(&now)) != OK)
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| 33 | panic(__FILE__, "PM couldn't get uptime", NO_NUM);
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| 34 |
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| 35 | /* Set timer argument and add timer to the list. */
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| 36 | tmr_arg(tp)->ta_int = arg;
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| 37 | prev_time = tmrs_settimer(&pm_timers,tp,now+ticks,watchdog,&next_time);
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| 38 |
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| 39 | /* Reschedule our synchronous alarm if necessary. */
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| 40 | if (! prev_time || prev_time > next_time) {
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| 41 | if (sys_setalarm(next_time, 1) != OK)
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| 42 | panic(__FILE__, "PM set timer couldn't set alarm.", NO_NUM);
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| 43 | }
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| 44 |
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| 45 | return;
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| 46 | }
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| 47 |
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| 48 | /*===========================================================================*
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| 49 | * pm_expire_timers *
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| 50 | *===========================================================================*/
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| 51 | PUBLIC void pm_expire_timers(clock_t now)
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| 52 | {
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| 53 | clock_t next_time;
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| 54 |
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| 55 | /* Check for expired timers and possibly reschedule an alarm. */
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| 56 | tmrs_exptimers(&pm_timers, now, &next_time);
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| 57 | if (next_time > 0) {
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| 58 | if (sys_setalarm(next_time, 1) != OK)
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| 59 | panic(__FILE__, "PM expire timer couldn't set alarm.", NO_NUM);
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| 60 | }
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| 61 | }
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| 62 |
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| 63 | /*===========================================================================*
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| 64 | * pm_cancel_timer *
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| 65 | *===========================================================================*/
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| 66 | PUBLIC void pm_cancel_timer(timer_t *tp)
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| 67 | {
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| 68 | clock_t next_time, prev_time;
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| 69 | prev_time = tmrs_clrtimer(&pm_timers, tp, &next_time);
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| 70 |
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| 71 | /* If the earliest timer has been removed, we have to set the alarm to
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| 72 | * the next timer, or cancel the alarm altogether if the last timer has
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| 73 | * been cancelled (next_time will be 0 then).
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| 74 | */
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| 75 | if (prev_time < next_time || ! next_time) {
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| 76 | if (sys_setalarm(next_time, 1) != OK)
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| 77 | panic(__FILE__, "PM expire timer couldn't set alarm.", NO_NUM);
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| 78 | }
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| 79 | }
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