104 lines
2.7 KiB
C
104 lines
2.7 KiB
C
/*
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* Copyright (c) 2008 Travis Geiselbrecht
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files
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* (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <err.h>
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#include <debug.h>
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#include <sys/types.h>
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#include <kernel/thread.h>
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#include <platform/timer.h>
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#include <platform/interrupts.h>
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#include <platform/debug.h>
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#include <platform/at91sam7.h>
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#define FIXED_1KHZ_TIMER 0
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static platform_timer_callback timer_func;
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static volatile time_t ticks = 0;
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#if FIXED_1KHZ_TIMER
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static volatile int timer_interval;
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static volatile int timer_downcount;
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#else
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static int timer_ms_per_tick;
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#endif
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time_t current_time(void)
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{
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return ticks;
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}
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static enum handler_return pit_irq_handler(void *arg)
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{
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AT91PIT *pit = AT91PIT_ADDR;
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unsigned n = PIT_PICNT(pit->PIVR);
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#if FIXED_1KHZ_TIMER
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ticks += n;
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timer_downcount -= n;
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if(timer_downcount <= 0) {
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timer_downcount = timer_interval;
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return timer_func(0, ticks);
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} else {
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return INT_NO_RESCHEDULE;
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}
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#else
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ticks += (n * timer_ms_per_tick);
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return timer_func(0, ticks);
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#endif
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}
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status_t platform_set_periodic_timer(platform_timer_callback callback,
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void *arg, time_t interval)
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{
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unsigned n;
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AT91PIT *pit = AT91PIT_ADDR;
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n = AT91_MCK_MHZ / 16 / 1000;
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dprintf(INFO, "timer: MCK=%dKHz, n=%d\n", AT91_MCK_MHZ / 1000, n);
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enter_critical_section();
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timer_func = callback;
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#if FIXED_1KHZ_TIMER
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timer_interval = interval;
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timer_downcount = interval;
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#else
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timer_ms_per_tick = interval;
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n *= interval;
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#endif
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pit->MR = PIT_PITEN | PIT_PITIEN | (n & 0xfffff);
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register_int_handler(PID_SYSIRQ, pit_irq_handler, 0);
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unmask_interrupt(PID_SYSIRQ);
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exit_critical_section();
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return NO_ERROR;
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}
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