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29a24134c1
The Generic Timer is an optional extension to an ARMv7-A implementation. The generic delay timer can be used from any architecture supported by the Trusted Firmware. In ARMv7 it is needed to check that this feature is present. In ARMv8 it is always present. Change-Id: Ib7e8ec13ffbb2f64445d4ee48ed00f26e34b79b7 Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
63 lines
1.5 KiB
C
63 lines
1.5 KiB
C
/*
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* Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <assert.h>
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#include <arch_features.h>
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#include <arch_helpers.h>
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#include <common/bl_common.h>
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#include <common/debug.h>
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#include <drivers/delay_timer.h>
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#include <drivers/generic_delay_timer.h>
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#include <plat/common/platform.h>
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/* Ticks elapsed in one second by a signal of 1 MHz */
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#define MHZ_TICKS_PER_SEC 1000000
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static timer_ops_t ops;
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static uint32_t get_timer_value(void)
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{
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/*
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* Generic delay timer implementation expects the timer to be a down
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* counter. We apply bitwise NOT operator to the tick values returned
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* by read_cntpct_el0() to simulate the down counter. The value is
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* clipped from 64 to 32 bits.
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*/
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return (uint32_t)(~read_cntpct_el0());
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}
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void generic_delay_timer_init_args(uint32_t mult, uint32_t div)
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{
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ops.get_timer_value = get_timer_value;
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ops.clk_mult = mult;
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ops.clk_div = div;
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timer_init(&ops);
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VERBOSE("Generic delay timer configured with mult=%u and div=%u\n",
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mult, div);
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}
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void generic_delay_timer_init(void)
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{
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assert(is_armv7_gentimer_present());
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/* Value in ticks */
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unsigned int mult = MHZ_TICKS_PER_SEC;
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/* Value in ticks per second (Hz) */
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unsigned int div = plat_get_syscnt_freq2();
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/* Reduce multiplier and divider by dividing them repeatedly by 10 */
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while (((mult % 10U) == 0U) && ((div % 10U) == 0U)) {
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mult /= 10U;
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div /= 10U;
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}
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generic_delay_timer_init_args(mult, div);
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}
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