1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License.  See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 2012 MIPS Technologies, Inc.  All rights reserved.
7 */
8#include <linux/init.h>
9#include <linux/irqchip/mips-gic.h>
10
11#include <asm/cpu.h>
12#include <asm/setup.h>
13#include <asm/time.h>
14#include <asm/irq.h>
15#include <asm/mips-boards/generic.h>
16
17static void __iomem *status_reg = (void __iomem *)0xbf000410;
18
19/*
20 * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect.
21 */
22static unsigned int __init estimate_cpu_frequency(void)
23{
24	unsigned int prid = read_c0_prid() & (PRID_COMP_MASK | PRID_IMP_MASK);
25	unsigned int tick = 0;
26	unsigned int freq;
27	unsigned int orig;
28	unsigned long flags;
29
30	local_irq_save(flags);
31
32	orig = readl(status_reg) & 0x2;		      /* get original sample */
33	/* wait for transition */
34	while ((readl(status_reg) & 0x2) == orig)
35		;
36	orig = orig ^ 0x2;			      /* flip the bit */
37
38	write_c0_count(0);
39
40	/* wait 1 second (the sampling clock transitions every 10ms) */
41	while (tick < 100) {
42		/* wait for transition */
43		while ((readl(status_reg) & 0x2) == orig)
44			;
45		orig = orig ^ 0x2;			      /* flip the bit */
46		tick++;
47	}
48
49	freq = read_c0_count();
50
51	local_irq_restore(flags);
52
53	mips_hpt_frequency = freq;
54
55	/* Adjust for processor */
56	if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
57		(prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
58		freq *= 2;
59
60	freq += 5000;	     /* rounding */
61	freq -= freq%10000;
62
63	return freq ;
64}
65
66void read_persistent_clock(struct timespec *ts)
67{
68	ts->tv_sec = 0;
69	ts->tv_nsec = 0;
70}
71
72int get_c0_perfcount_int(void)
73{
74	if (gic_present)
75		return gic_get_c0_perfcount_int();
76	if (cp0_perfcount_irq >= 0)
77		return MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
78	return -1;
79}
80EXPORT_SYMBOL_GPL(get_c0_perfcount_int);
81
82unsigned int get_c0_compare_int(void)
83{
84	if (gic_present)
85		return gic_get_c0_compare_int();
86	return MIPS_CPU_IRQ_BASE + cp0_compare_irq;
87}
88
89void __init plat_time_init(void)
90{
91	unsigned int est_freq;
92
93	est_freq = estimate_cpu_frequency();
94
95	pr_debug("CPU frequency %d.%02d MHz\n", (est_freq / 1000000),
96		(est_freq % 1000000) * 100 / 1000000);
97
98	mips_scroll_message();
99}
100