1 /* 2 * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 #include <arch_helpers.h> 8 #include <assert.h> 9 #include <bl_common.h> 10 #include <debug.h> 11 #include <delay_timer.h> 12 #include <generic_delay_timer.h> 13 #include <platform.h> 14 15 /* Ticks elapsed in one second by a signal of 1 MHz */ 16 #define MHZ_TICKS_PER_SEC 1000000 17 18 static timer_ops_t ops; 19 20 static uint32_t get_timer_value(void) 21 { 22 /* 23 * Generic delay timer implementation expects the timer to be a down 24 * counter. We apply bitwise NOT operator to the tick values returned 25 * by read_cntpct_el0() to simulate the down counter. The value is 26 * clipped from 64 to 32 bits. 27 */ 28 return (uint32_t)(~read_cntpct_el0()); 29 } 30 31 void generic_delay_timer_init_args(uint32_t mult, uint32_t div) 32 { 33 ops.get_timer_value = get_timer_value; 34 ops.clk_mult = mult; 35 ops.clk_div = div; 36 37 timer_init(&ops); 38 39 VERBOSE("Generic delay timer configured with mult=%u and div=%u\n", 40 mult, div); 41 } 42 43 void generic_delay_timer_init(void) 44 { 45 /* Value in ticks */ 46 unsigned int mult = MHZ_TICKS_PER_SEC; 47 48 /* Value in ticks per second (Hz) */ 49 unsigned int div = plat_get_syscnt_freq2(); 50 51 /* Reduce multiplier and divider by dividing them repeatedly by 10 */ 52 while ((mult % 10 == 0) && (div % 10 == 0)) { 53 mult /= 10; 54 div /= 10; 55 } 56 57 generic_delay_timer_init_args(mult, div); 58 } 59 60
