1/*
 2 *  linux/arch/arm/plat-versatile/sched-clock.c
 3 *
 4 *  Copyright (C) 1999 - 2003 ARM Limited
 5 *  Copyright (C) 2000 Deep Blue Solutions Ltd
 6 *
 7 * This program is free software; you can redistribute it and/or modify
 8 * it under the terms of the GNU General Public License as published by
 9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20 */
21#include <linux/io.h>
22#include <linux/sched.h>
23
24#include <asm/sched_clock.h>
25#include <plat/sched_clock.h>
26
27static DEFINE_CLOCK_DATA(cd);
28static void __iomem *ctr;
29
30/*
31 * Constants generated by clocks_calc_mult_shift(m, s, 24MHz, NSEC_PER_SEC, 60).
32 * This gives a resolution of about 41ns and a wrap period of about 178s.
33 */
34#define SC_MULT		2796202667u
35#define SC_SHIFT	26
36
37unsigned long long notrace sched_clock(void)
38{
39	if (ctr) {
40		u32 cyc = readl(ctr);
41		return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0,
42						SC_MULT, SC_SHIFT);
43	} else
44		return 0;
45}
46
47static void notrace versatile_update_sched_clock(void)
48{
49	u32 cyc = readl(ctr);
50	update_sched_clock(&cd, cyc, (u32)~0);
51}
52
53void __init versatile_sched_clock_init(void __iomem *reg, unsigned long rate)
54{
55	ctr = reg;
56	init_fixed_sched_clock(&cd, versatile_update_sched_clock,
57			       32, rate, SC_MULT, SC_SHIFT);
58}