1 /* 1
2 * This file is subject to the terms and condi
3 * License. See the file "COPYING" in the mai
4 * for more details.
5 *
6 * Time operations for IP22 machines. Original
7 * Ralf Baechle or David S. Miller (sorry guys
8 *
9 * Copyright (C) 2001 by Ladislav Michl
10 * Copyright (C) 2003, 06 Ralf Baechle (ralf@l
11 */
12 #include <linux/bcd.h>
13 #include <linux/i8253.h>
14 #include <linux/init.h>
15 #include <linux/irq.h>
16 #include <linux/kernel.h>
17 #include <linux/interrupt.h>
18 #include <linux/kernel_stat.h>
19 #include <linux/time.h>
20 #include <linux/ftrace.h>
21
22 #include <asm/cpu.h>
23 #include <asm/mipsregs.h>
24 #include <asm/io.h>
25 #include <asm/irq.h>
26 #include <asm/time.h>
27 #include <asm/sgialib.h>
28 #include <asm/sgi/ioc.h>
29 #include <asm/sgi/hpc3.h>
30 #include <asm/sgi/ip22.h>
31
32 static unsigned long dosample(void)
33 {
34 u32 ct0, ct1;
35 u8 msb;
36
37 /* Start the counter. */
38 sgint->tcword = (SGINT_TCWORD_CNT2 | S
39 SGINT_TCWORD_MRGEN);
40 sgint->tcnt2 = SGINT_TCSAMP_COUNTER &
41 sgint->tcnt2 = SGINT_TCSAMP_COUNTER >>
42
43 /* Get initial counter invariant */
44 ct0 = read_c0_count();
45
46 /* Latch and spin until top byte of co
47 do {
48 writeb(SGINT_TCWORD_CNT2 | SGI
49 (void) readb(&sgint->tcnt2);
50 msb = readb(&sgint->tcnt2);
51 ct1 = read_c0_count();
52 } while (msb);
53
54 /* Stop the counter. */
55 writeb(SGINT_TCWORD_CNT2 | SGINT_TCWOR
56 &sgint->tcword);
57 /*
58 * Return the difference, this is how
59 * for every 1/HZ seconds. We round of
60 * clock (= 1000000 / HZ / 2).
61 */
62
63 return (ct1 - ct0) / (500000/HZ) * (50
64 }
65
66 /*
67 * Here we need to calibrate the cycle counter
68 */
69 __init void plat_time_init(void)
70 {
71 unsigned long r4k_ticks[3];
72 unsigned long r4k_tick;
73
74 /*
75 * Figure out the r4k offset, the algo
76 * _all_ cases as long as the 8254 cou
77 * an interrupt driving timer it does
78 * we are using the onchip r4k counter
79 * purpose, but for r4k_offset calcula
80 * There are other very complicated wa
81 * but this one works just fine so I a
82 */
83 printk(KERN_INFO "Calibrating system t
84 dosample(); /* Prime cache. */
85 dosample(); /* Prime cache. */
86 /* Zero is NOT an option. */
87 do {
88 r4k_ticks[0] = dosample();
89 } while (!r4k_ticks[0]);
90 do {
91 r4k_ticks[1] = dosample();
92 } while (!r4k_ticks[1]);
93
94 if (r4k_ticks[0] != r4k_ticks[1]) {
95 printk("warning: timer counts
96 r4k_ticks[2] = dosample();
97 if (r4k_ticks[2] == r4k_ticks[
98 || r4k_ticks[2] == r4k_tic
99 r4k_tick = r4k_ticks[2
100 else {
101 printk("disagreement,
102 r4k_tick = (r4k_ticks[
103 + r4k_ticks
104 }
105 } else
106 r4k_tick = r4k_ticks[0];
107
108 printk("%d [%d.%04d MHz CPU]\n", (int)
109 (int) (r4k_tick / (500000 / HZ
110 (int) (r4k_tick % (500000 / HZ
111
112 mips_hpt_frequency = r4k_tick * HZ;
113
114 if (ip22_is_fullhouse())
115 setup_pit_timer();
116 }
117
118 /* Generic SGI handler for (spurious) 8254 int
119 void __irq_entry indy_8254timer_irq(void)
120 {
121 int irq = SGI_8254_0_IRQ;
122 ULONG cnt;
123 char c;
124
125 irq_enter();
126 kstat_incr_irq_this_cpu(irq);
127 printk(KERN_ALERT "Oops, got 8254 inte
128 ArcRead(0, &c, 1, &cnt);
129 ArcEnterInteractiveMode();
130 irq_exit();
131 }
132
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