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 
15 static void __iomem *versatile_sys_24mhz;
16 
17 static u64 notrace versatile_sys_24mhz_read(void)
18 {
19 	return readl(versatile_sys_24mhz);
20 }
21 
22 static int __init versatile_sched_clock_init(struct device_node *node)
23 {
24 	void __iomem *base = of_iomap(node, 0);
25 
26 	of_node_clear_flag(node, OF_POPULATED);
27 
28 	if (!base)
29 		return -ENXIO;
30 
31 	versatile_sys_24mhz = base + SYS_24MHZ;
32 
33 	sched_clock_register(versatile_sys_24mhz_read, 32, 24000000);
34 
35 	return 0;
36 }
37 TIMER_OF_DECLARE(vexpress, "arm,vexpress-sysreg",
38 		       versatile_sched_clock_init);
39 TIMER_OF_DECLARE(versatile, "arm,versatile-sysreg",
40 		       versatile_sched_clock_init);
41