1 /*
2 * arch/arm/plat-iop/time.c
3 *
4 * Timer code for IOP32x and IOP33x based systems
5 *
6 * Author: Deepak Saxena <dsaxena@mvista.com>
7 *
8 * Copyright 2002-2003 MontaVista Software Inc.
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
14 */
15
16 #include <linux/kernel.h>
17 #include <linux/interrupt.h>
18 #include <linux/time.h>
19 #include <linux/init.h>
20 #include <linux/timex.h>
21 #include <linux/io.h>
22 #include <mach/hardware.h>
23 #include <asm/irq.h>
24 #include <asm/uaccess.h>
25 #include <asm/mach/irq.h>
26 #include <asm/mach/time.h>
27 #include <mach/time.h>
28
29 static unsigned long ticks_per_jiffy;
30 static unsigned long ticks_per_usec;
31 static unsigned long next_jiffy_time;
32
iop_gettimeoffset(void)33 unsigned long iop_gettimeoffset(void)
34 {
35 unsigned long offset, temp;
36
37 /* enable cp6, if necessary, to avoid taking the overhead of an
38 * undefined instruction trap
39 */
40 asm volatile (
41 "mrc p15, 0, %0, c15, c1, 0\n\t"
42 "tst %0, #(1 << 6)\n\t"
43 "orreq %0, %0, #(1 << 6)\n\t"
44 "mcreq p15, 0, %0, c15, c1, 0\n\t"
45 #ifdef CONFIG_CPU_XSCALE
46 "mrceq p15, 0, %0, c15, c1, 0\n\t"
47 "moveq %0, %0\n\t"
48 "subeq pc, pc, #4\n\t"
49 #endif
50 : "=r"(temp) : : "cc");
51
52 offset = next_jiffy_time - read_tcr1();
53
54 return offset / ticks_per_usec;
55 }
56
57 static irqreturn_t
iop_timer_interrupt(int irq,void * dev_id)58 iop_timer_interrupt(int irq, void *dev_id)
59 {
60 write_tisr(1);
61
62 while ((signed long)(next_jiffy_time - read_tcr1())
63 >= ticks_per_jiffy) {
64 timer_tick();
65 next_jiffy_time -= ticks_per_jiffy;
66 }
67
68 return IRQ_HANDLED;
69 }
70
71 static struct irqaction iop_timer_irq = {
72 .name = "IOP Timer Tick",
73 .handler = iop_timer_interrupt,
74 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
75 };
76
77 static unsigned long iop_tick_rate;
get_iop_tick_rate(void)78 unsigned long get_iop_tick_rate(void)
79 {
80 return iop_tick_rate;
81 }
82 EXPORT_SYMBOL(get_iop_tick_rate);
83
iop_init_time(unsigned long tick_rate)84 void __init iop_init_time(unsigned long tick_rate)
85 {
86 u32 timer_ctl;
87
88 ticks_per_jiffy = (tick_rate + HZ/2) / HZ;
89 ticks_per_usec = tick_rate / 1000000;
90 next_jiffy_time = 0xffffffff;
91 iop_tick_rate = tick_rate;
92
93 timer_ctl = IOP_TMR_EN | IOP_TMR_PRIVILEGED |
94 IOP_TMR_RELOAD | IOP_TMR_RATIO_1_1;
95
96 /*
97 * We use timer 0 for our timer interrupt, and timer 1 as
98 * monotonic counter for tracking missed jiffies.
99 */
100 write_trr0(ticks_per_jiffy - 1);
101 write_tmr0(timer_ctl);
102 write_trr1(0xffffffff);
103 write_tmr1(timer_ctl);
104
105 setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq);
106 }
107