Linux Kernel  3.7.1
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time.c
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1 /*
2  * Copyright (C) 2001-2006 Storlink, Corp.
3  * Copyright (C) 2008-2009 Paulius Zaleckas <[email protected]>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
9  */
10 #include <linux/interrupt.h>
11 #include <linux/irq.h>
12 #include <linux/io.h>
13 #include <mach/hardware.h>
14 #include <mach/global_reg.h>
15 #include <asm/mach/time.h>
16 
17 /*
18  * Register definitions for the timers
19  */
20 #define TIMER_COUNT(BASE_ADDR) (BASE_ADDR + 0x00)
21 #define TIMER_LOAD(BASE_ADDR) (BASE_ADDR + 0x04)
22 #define TIMER_MATCH1(BASE_ADDR) (BASE_ADDR + 0x08)
23 #define TIMER_MATCH2(BASE_ADDR) (BASE_ADDR + 0x0C)
24 #define TIMER_CR(BASE_ADDR) (BASE_ADDR + 0x30)
25 
26 #define TIMER_1_CR_ENABLE (1 << 0)
27 #define TIMER_1_CR_CLOCK (1 << 1)
28 #define TIMER_1_CR_INT (1 << 2)
29 #define TIMER_2_CR_ENABLE (1 << 3)
30 #define TIMER_2_CR_CLOCK (1 << 4)
31 #define TIMER_2_CR_INT (1 << 5)
32 #define TIMER_3_CR_ENABLE (1 << 6)
33 #define TIMER_3_CR_CLOCK (1 << 7)
34 #define TIMER_3_CR_INT (1 << 8)
35 
36 /*
37  * IRQ handler for the timer
38  */
39 static irqreturn_t gemini_timer_interrupt(int irq, void *dev_id)
40 {
41  timer_tick();
42 
43  return IRQ_HANDLED;
44 }
45 
46 static struct irqaction gemini_timer_irq = {
47  .name = "Gemini Timer Tick",
48  .flags = IRQF_DISABLED | IRQF_TIMER,
49  .handler = gemini_timer_interrupt,
50 };
51 
52 /*
53  * Set up timer interrupt, and return the current time in seconds.
54  */
56 {
57  unsigned int tick_rate, reg_v;
58 
60  tick_rate = REG_TO_AHB_SPEED(reg_v) * 1000000;
61 
62  printk(KERN_INFO "Bus: %dMHz", tick_rate / 1000000);
63 
64  tick_rate /= 6; /* APB bus run AHB*(1/6) */
65 
66  switch(reg_v & CPU_AHB_RATIO_MASK) {
67  case CPU_AHB_1_1:
68  printk(KERN_CONT "(1/1)\n");
69  break;
70  case CPU_AHB_3_2:
71  printk(KERN_CONT "(3/2)\n");
72  break;
73  case CPU_AHB_24_13:
74  printk(KERN_CONT "(24/13)\n");
75  break;
76  case CPU_AHB_2_1:
77  printk(KERN_CONT "(2/1)\n");
78  break;
79  }
80 
81  /*
82  * Make irqs happen for the system timer
83  */
84  setup_irq(IRQ_TIMER2, &gemini_timer_irq);
85  /* Start the timer */
89 }