1 /*
2  * Copyright (C) 2012-2015 Masahiro Yamada <yamada.masahiro@socionext.com>
3  *
4  * SPDX-License-Identifier:	GPL-2.0+
5  */
6 
7 #include <common.h>
8 #include <linux/io.h>
9 
10 #include "arm-mpcore.h"
11 
12 #define PERIPHCLK (50 * 1000 * 1000) /* 50 MHz */
13 #define PRESCALER ((PERIPHCLK) / (CONFIG_SYS_TIMER_RATE) - 1)
14 
15 static void *get_global_timer_base(void)
16 {
17 	void *val;
18 
19 	asm("mrc p15, 4, %0, c15, c0, 0" : "=r" (val) : : "memory");
20 
21 	return val + GLOBAL_TIMER_OFFSET;
22 }
23 
24 unsigned long timer_read_counter(void)
25 {
26 	/*
27 	 * ARM 64bit Global Timer is too much for our purpose.
28 	 * We use only lower 32 bit of the timer counter.
29 	 */
30 	return readl(get_global_timer_base() + GTIMER_CNT_L);
31 }
32 
33 int timer_init(void)
34 {
35 	/* enable timer */
36 	writel(PRESCALER << 8 | 1, get_global_timer_base() + GTIMER_CTRL);
37 
38 	return 0;
39 }
40