1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2012-2015 Masahiro Yamada <yamada.masahiro@socionext.com>
4  */
5 
6 #include <common.h>
7 #include <linux/io.h>
8 
9 #include "arm-mpcore.h"
10 
11 #define PERIPHCLK (50 * 1000 * 1000) /* 50 MHz */
12 #define PRESCALER ((PERIPHCLK) / (CONFIG_SYS_TIMER_RATE) - 1)
13 
14 static void *get_global_timer_base(void)
15 {
16 	void *val;
17 
18 	asm("mrc p15, 4, %0, c15, c0, 0" : "=r" (val) : : "memory");
19 
20 	return val + GLOBAL_TIMER_OFFSET;
21 }
22 
23 unsigned long timer_read_counter(void)
24 {
25 	/*
26 	 * ARM 64bit Global Timer is too much for our purpose.
27 	 * We use only lower 32 bit of the timer counter.
28 	 */
29 	return readl(get_global_timer_base() + GTIMER_CNT_L);
30 }
31 
32 int timer_init(void)
33 {
34 	/* enable timer */
35 	writel(PRESCALER << 8 | 1, get_global_timer_base() + GTIMER_CTRL);
36 
37 	return 0;
38 }
39