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https://github.com/brain-hackers/u-boot-brain
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04ff9ab158
The current implementation has the timer being started before the interrupt handler is installed. It the interrupt occurs before the handler is installed, the timer interrupt is never reset and the timer stops Signed-off-by: Graeme Russ <graeme.russ@gmail.com>
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
/*
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* (C) Copyright 2002
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* Daniel Engström, Omicron Ceti AB <daniel@omicron.se>.
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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/* stuff specific for the sc520, but independent of implementation */
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#include <common.h>
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#include <asm/interrupt.h>
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#include <asm/ic/sc520.h>
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void sc520_timer_isr(void)
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{
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/* Ack the GP Timer Interrupt */
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write_mmcr_byte (SC520_GPTMRSTA, 0x02);
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}
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int timer_init(void)
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{
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/* Map GP Timer 1 to Master PIC IR0 */
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write_mmcr_byte (SC520_GPTMR1MAP, 0x01);
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/* Disable GP Timers 1 & 2 - Allow configuration writes */
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write_mmcr_word (SC520_GPTMR1CTL, 0x4000);
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write_mmcr_word (SC520_GPTMR2CTL, 0x4000);
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/* Reset GP Timers 1 & 2 */
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write_mmcr_word (SC520_GPTMR1CNT, 0x0000);
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write_mmcr_word (SC520_GPTMR2CNT, 0x0000);
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/* Setup GP Timer 2 as a 100kHz (10us) prescaler */
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write_mmcr_word (SC520_GPTMR2MAXCMPA, 83);
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write_mmcr_word (SC520_GPTMR2CTL, 0xc001);
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/* Setup GP Timer 1 as a 1000 Hz (1ms) interrupt generator */
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write_mmcr_word (SC520_GPTMR1MAXCMPA, 100);
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write_mmcr_word (SC520_GPTMR1CTL, 0xe009);
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/* Register the SC520 specific timer interrupt handler */
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register_timer_isr (sc520_timer_isr);
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/* Install interrupt handler for GP Timer 1 */
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irq_install_handler (0, timer_isr, NULL);
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unmask_irq (0);
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/* Clear the GP Timer 1 status register to get the show rolling*/
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write_mmcr_byte (SC520_GPTMRSTA, 0x02);
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return 0;
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}
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void udelay(unsigned long usec)
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{
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int m = 0;
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long u;
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read_mmcr_word (SC520_SWTMRMILLI);
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read_mmcr_word (SC520_SWTMRMICRO);
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do {
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m += read_mmcr_word (SC520_SWTMRMILLI);
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u = read_mmcr_word (SC520_SWTMRMICRO) + (m * 1000);
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} while (u < usec);
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}
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