1 /*
2  * This program is free software; you can redistribute it and/or modify
3  * it under the terms of the GNU General Public License version 2 as
4  * published by the Free Software Foundation.
5  *
6  * This program is distributed in the hope that it will be useful,
7  * but WITHOUT ANY WARRANTY; without even the implied warranty of
8  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
9  * GNU General Public License for more details.
10  *
11  * Copyright (C) 2014 ARM Limited
12  */
13 
14 #include <linux/clocksource.h>
15 #include <linux/io.h>
16 #include <linux/of_address.h>
17 #include <linux/sched_clock.h>
18 
19 #define SYS_24MHZ 0x05c
20 
21 static void __iomem *versatile_sys_24mhz;
22 
23 static u64 notrace versatile_sys_24mhz_read(void)
24 {
25 	return readl(versatile_sys_24mhz);
26 }
27 
28 static int __init versatile_sched_clock_init(struct device_node *node)
29 {
30 	void __iomem *base = of_iomap(node, 0);
31 
32 	if (!base)
33 		return -ENXIO;
34 
35 	versatile_sys_24mhz = base + SYS_24MHZ;
36 
37 	sched_clock_register(versatile_sys_24mhz_read, 32, 24000000);
38 
39 	return 0;
40 }
41 TIMER_OF_DECLARE(vexpress, "arm,vexpress-sysreg",
42 		       versatile_sched_clock_init);
43 TIMER_OF_DECLARE(versatile, "arm,versatile-sysreg",
44 		       versatile_sched_clock_init);
45