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malta-time.c
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1 /*
2  * Carsten Langgaard, [email protected]
3  * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved.
4  *
5  * This program is free software; you can distribute it and/or modify it
6  * under the terms of the GNU General Public License (Version 2) as
7  * published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12  * for more details.
13  *
14  * You should have received a copy of the GNU General Public License along
15  * with this program; if not, write to the Free Software Foundation, Inc.,
16  * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
17  *
18  * Setting up the clock on the MIPS boards.
19  */
20 
21 #include <linux/types.h>
22 #include <linux/i8253.h>
23 #include <linux/init.h>
24 #include <linux/kernel_stat.h>
25 #include <linux/sched.h>
26 #include <linux/spinlock.h>
27 #include <linux/interrupt.h>
28 #include <linux/time.h>
29 #include <linux/timex.h>
30 #include <linux/mc146818rtc.h>
31 
32 #include <asm/mipsregs.h>
33 #include <asm/mipsmtregs.h>
34 #include <asm/hardirq.h>
35 #include <asm/irq.h>
36 #include <asm/div64.h>
37 #include <asm/cpu.h>
38 #include <asm/setup.h>
39 #include <asm/time.h>
40 #include <asm/mc146818-time.h>
41 #include <asm/msc01_ic.h>
42 
44 #include <asm/mips-boards/prom.h>
45 
47 
48 unsigned long cpu_khz;
49 
50 static int mips_cpu_timer_irq;
51 static int mips_cpu_perf_irq;
52 extern int cp0_perfcount_irq;
53 
54 static void mips_timer_dispatch(void)
55 {
56  do_IRQ(mips_cpu_timer_irq);
57 }
58 
59 static void mips_perf_dispatch(void)
60 {
61  do_IRQ(mips_cpu_perf_irq);
62 }
63 
64 /*
65  * Estimate CPU frequency. Sets mips_hpt_frequency as a side-effect
66  */
67 static unsigned int __init estimate_cpu_frequency(void)
68 {
69  unsigned int prid = read_c0_prid() & 0xffff00;
70  unsigned int count;
71 
72  unsigned long flags;
73  unsigned int start;
74 
75  local_irq_save(flags);
76 
77  /* Start counter exactly on falling edge of update flag */
78  while (CMOS_READ(RTC_REG_A) & RTC_UIP);
79  while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
80 
81  /* Start r4k counter. */
82  start = read_c0_count();
83 
84  /* Read counter exactly on falling edge of update flag */
85  while (CMOS_READ(RTC_REG_A) & RTC_UIP);
86  while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
87 
88  count = read_c0_count() - start;
89 
90  /* restore interrupts */
91  local_irq_restore(flags);
92 
94  if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
95  (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
96  count *= 2;
97 
98  count += 5000; /* round */
99  count -= count%10000;
100 
101  return count;
102 }
103 
105 {
106  ts->tv_sec = mc146818_get_cmos_time();
107  ts->tv_nsec = 0;
108 }
109 
110 static void __init plat_perf_setup(void)
111 {
112 #ifdef MSC01E_INT_BASE
113  if (cpu_has_veic) {
114  set_vi_handler(MSC01E_INT_PERFCTR, mips_perf_dispatch);
115  mips_cpu_perf_irq = MSC01E_INT_BASE + MSC01E_INT_PERFCTR;
116  } else
117 #endif
118  if (cp0_perfcount_irq >= 0) {
119  if (cpu_has_vint)
120  set_vi_handler(cp0_perfcount_irq, mips_perf_dispatch);
121  mips_cpu_perf_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
122 #ifdef CONFIG_SMP
123  irq_set_handler(mips_cpu_perf_irq, handle_percpu_irq);
124 #endif
125  }
126 }
127 
128 unsigned int __cpuinit get_c0_compare_int(void)
129 {
130 #ifdef MSC01E_INT_BASE
131  if (cpu_has_veic) {
132  set_vi_handler(MSC01E_INT_CPUCTR, mips_timer_dispatch);
133  mips_cpu_timer_irq = MSC01E_INT_BASE + MSC01E_INT_CPUCTR;
134  } else
135 #endif
136  {
137  if (cpu_has_vint)
138  set_vi_handler(cp0_compare_irq, mips_timer_dispatch);
139  mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
140  }
141 
142  return mips_cpu_timer_irq;
143 }
144 
146 {
147  unsigned int est_freq;
148 
149  /* Set Data mode - binary. */
151 
152  est_freq = estimate_cpu_frequency();
153 
154  printk("CPU frequency %d.%02d MHz\n", est_freq/1000000,
155  (est_freq%1000000)*100/1000000);
156 
157  cpu_khz = est_freq / 1000;
158 
160 #ifdef CONFIG_I8253 /* Only Malta has a PIT */
161  setup_pit_timer();
162 #endif
163 
164  plat_perf_setup();
165 }