tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#include <linux/types.h>
2#include <linux/init.h>
3#include <linux/kernel_stat.h>
4#include <linux/sched.h>
5#include <linux/spinlock.h>
6#include <linux/interrupt.h>
7#include <linux/mc146818rtc.h>
8#include <linux/smp.h>
9#include <linux/timex.h>
10
11#include <asm/hardirq.h>
12#include <asm/div64.h>
13#include <asm/cpu.h>
14#include <asm/setup.h>
15#include <asm/time.h>
16#include <asm/irq.h>
17#include <asm/mc146818-time.h>
18#include <asm/msc01_ic.h>
19
20#include <asm/mips-boards/generic.h>
21#include <asm/mips-boards/prom.h>
22#include <asm/mips-boards/simint.h>
23
24
25unsigned long cpu_khz;
26
27/*
28 * Estimate CPU frequency. Sets mips_hpt_frequency as a side-effect
29 */
30static unsigned int __init estimate_cpu_frequency(void)
31{
32 unsigned int prid = read_c0_prid() & 0xffff00;
33 unsigned int count;
34
35#if 1
36 /*
37 * hardwire the board frequency to 12MHz.
38 */
39
40 if ((prid == (PRID_COMP_MIPS | PRID_IMP_20KC)) ||
41 (prid == (PRID_COMP_MIPS | PRID_IMP_25KF)))
42 count = 12000000;
43 else
44 count = 6000000;
45#else
46 unsigned int flags;
47
48 local_irq_save(flags);
49
50 /* Start counter exactly on falling edge of update flag */
51 while (CMOS_READ(RTC_REG_A) & RTC_UIP);
52 while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
53
54 /* Start r4k counter. */
55 write_c0_count(0);
56
57 /* Read counter exactly on falling edge of update flag */
58 while (CMOS_READ(RTC_REG_A) & RTC_UIP);
59 while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
60
61 count = read_c0_count();
62
63 /* restore interrupts */
64 local_irq_restore(flags);
65#endif
66
67 mips_hpt_frequency = count;
68
69 if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
70 (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
71 count *= 2;
72
73 count += 5000; /* round */
74 count -= count%10000;
75
76 return count;
77}
78
79static int mips_cpu_timer_irq;
80
81static void mips_timer_dispatch(void)
82{
83 do_IRQ(mips_cpu_timer_irq);
84}
85
86
87unsigned __cpuinit get_c0_compare_int(void)
88{
89#ifdef MSC01E_INT_BASE
90 if (cpu_has_veic) {
91 set_vi_handler(MSC01E_INT_CPUCTR, mips_timer_dispatch);
92 mips_cpu_timer_irq = MSC01E_INT_BASE + MSC01E_INT_CPUCTR;
93
94 return mips_cpu_timer_irq;
95 }
96#endif
97 if (cpu_has_vint)
98 set_vi_handler(cp0_compare_irq, mips_timer_dispatch);
99 mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
100
101 return mips_cpu_timer_irq;
102}
103
104void __init plat_time_init(void)
105{
106 unsigned int est_freq;
107
108 /* Set Data mode - binary. */
109 CMOS_WRITE(CMOS_READ(RTC_CONTROL) | RTC_DM_BINARY, RTC_CONTROL);
110
111 est_freq = estimate_cpu_frequency();
112
113 printk(KERN_INFO "CPU frequency %d.%02d MHz\n", est_freq / 1000000,
114 (est_freq % 1000000) * 100 / 1000000);
115
116 cpu_khz = est_freq / 1000;
117}