1 /*
2 * linux/include/asm-arm/arch-mx1ads/time.h
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17 *
18 * Copyright (C) 2002 Shane Nay (shane@minirl.com)
19 */
20 #include <asm/system.h>
21
22 /*
23 * Where is the timer (VA)?
24 */
25 #define TIMER0_VA_BASE (IO_ADDRESS(MX1ADS_TIM1_BASE)+0x00000000)
26 #define TIMER1_VA_BASE (IO_ADDRESS(MX1ADS_TIM2_BASE)+0x00000000)
27
28 /*
29 * How long is the timer interval?
30 *
31 * Note-
32 * Clocking is not accurate enough. Need to change the input
33 * to CLKOUT, and fix what those values are. However,
34 * first need to evaluate what a reasonable value is
35 * as several other things depend upon that clock.
36 *
37 */
38
39 #define TIMER_RELOAD (328)
40
41 #define TICKS2USECS(x) ((x) * 30)
42
43 #define TIM_32KHZ 0x08
44 #define TIM_INTEN 0x10
45 #define TIM_ENAB 0x01
46
47 /*
48 * What does it look like?
49 */
50 typedef struct TimerStruct {
51 unsigned long TimerControl;
52 unsigned long TimerPrescaler;
53 unsigned long TimerCompare;
54 unsigned long TimerCapture;
55 unsigned long TimerCounter;
56 unsigned long TimerClear; /* Clear Status */
57 } TimerStruct_t;
58
59 extern unsigned long (*gettimeoffset) (void);
60
61 /*
62 * Returns number of ms since last clock interrupt. Note that interrupts
63 * will have been disabled by do_gettimeoffset()
64 */
65 static unsigned long
mx1ads_gettimeoffset(void)66 mx1ads_gettimeoffset(void)
67 {
68 volatile TimerStruct_t *timer1 = (TimerStruct_t *) TIMER1_VA_BASE;
69 unsigned long ticks, status;
70
71 /*
72 * Get the current number of ticks. Note that there is a race
73 * condition between us reading the timer and checking for
74 * an interrupt. We get around this by ensuring that the
75 * counter has not reloaded between our two reads.
76 */
77 ticks = timer1->TimerCounter;
78
79 /*
80 * Interrupt pending? If so, we've reloaded once already.
81 */
82 if (timer1->TimerClear & 1)
83 ticks += TIMER_RELOAD;
84
85 /*
86 * Convert the ticks to usecs
87 */
88 return TICKS2USECS(ticks);
89 }
90
91 /*
92 * IRQ handler for the timer
93 */
94 static void
mx1ads_timer_interrupt(int irq,void * dev_id,struct pt_regs * regs)95 mx1ads_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
96 {
97 volatile TimerStruct_t *timer1 =
98 (volatile TimerStruct_t *) TIMER1_VA_BASE;
99 // ...clear the interrupt
100 if (timer1->TimerClear) {
101 timer1->TimerClear = 0x0;
102 }
103
104 do_timer(regs);
105 do_profile(regs);
106 }
107
108 /*
109 * Set up timer interrupt, and return the current time in seconds.
110 */
111 static inline void
setup_timer(void)112 setup_timer(void)
113 {
114 volatile TimerStruct_t *timer0 =
115 (volatile TimerStruct_t *) TIMER0_VA_BASE;
116 volatile TimerStruct_t *timer1 =
117 (volatile TimerStruct_t *) TIMER1_VA_BASE;
118
119
120 timer_irq.handler = mx1ads_timer_interrupt;
121
122 /*
123 * Initialise to a known state (all timers off, and timing reset)
124 */
125 timer0->TimerControl = 0;
126 timer1->TimerControl = 0;
127 timer0->TimerPrescaler = 0;
128 timer1->TimerPrescaler = 0;
129
130 timer1->TimerCompare = 328;
131 timer1->TimerControl = (TIM_32KHZ | TIM_INTEN | TIM_ENAB);
132
133 /*
134 * Make irqs happen for the system timer
135 */
136 setup_arm_irq(TIM2_INT, &timer_irq);
137 gettimeoffset = mx1ads_gettimeoffset;
138 }
139