coreboot-kgpe-d16/payloads/libpayload/drivers/timer/cygnus.c

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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2015 Google Electronics
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <libpayload.h>
struct cygnus_timer {
u32 gtim_glob_low;
u32 gtim_glob_hi;
u32 gtim_glob_ctrl;
};
static struct cygnus_timer * const timer_ptr =
(void *)CONFIG_LP_IPROC_PERIPH_GLB_TIM_REG_BASE;
uint64_t timer_hz(void)
{
/*
* this is set up by coreboot as follows:
*
* PERIPH_CLOCK /
* (((TIMER_GLB_TIM_CTRL_PRESC & TIMER_GLB_TIM_CTRL_PRESC_MASK)>>8) + 1)
*
* where PERIPH_CLOCK is typically 500000000.
*/
return 500000000;
}
uint64_t timer_raw_value(void)
{
uint64_t cur_tick;
uint32_t count_h;
uint32_t count_l;
do {
count_h = readl(&timer_ptr->gtim_glob_hi);
count_l = readl(&timer_ptr->gtim_glob_low);
cur_tick = readl(&timer_ptr->gtim_glob_hi);
} while (cur_tick != count_h);
return (cur_tick << 32) + count_l;
}