1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 * Copyright (C) 2014 ARM Limited
5 */
6
7#include <linux/clocksource.h>
8#include <linux/io.h>
9#include <linux/of.h>
10#include <linux/of_address.h>
11#include <linux/sched_clock.h>
12
13#define SYS_24MHZ 0x05c
14
15static void __iomem *versatile_sys_24mhz;
16
17static u64 notrace versatile_sys_24mhz_read(void)
18{
19 return readl(addr: versatile_sys_24mhz);
20}
21
22static int __init versatile_sched_clock_init(struct device_node *node)
23{
24 void __iomem *base = of_iomap(node, index: 0);
25
26 of_node_clear_flag(n: node, OF_POPULATED);
27
28 if (!base)
29 return -ENXIO;
30
31 versatile_sys_24mhz = base + SYS_24MHZ;
32
33 sched_clock_register(read: versatile_sys_24mhz_read, bits: 32, rate: 24000000);
34
35 return 0;
36}
37TIMER_OF_DECLARE(vexpress, "arm,vexpress-sysreg",
38 versatile_sched_clock_init);
39TIMER_OF_DECLARE(versatile, "arm,versatile-sysreg",
40 versatile_sched_clock_init);
41

source code of linux/drivers/clocksource/timer-versatile.c