1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
/*
* linux/arch/arm/mach-imx/time.c
*
* Copyright (C) 2000-2001 Deep Blue Solutions
* Copyright (C) 2002 Shane Nay (shane@minirl.com)
* Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/time.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <mach/hardware.h>
#include <asm/leds.h>
#include <asm/irq.h>
#include <asm/mach/time.h>
/* Use timer 1 as system timer */
#define TIMER_BASE IMX_TIM1_BASE
static struct clock_event_device clockevent_imx;
static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
/*
* IRQ handler for the timer
*/
static irqreturn_t
imx_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &clockevent_imx;
uint32_t tstat;
irqreturn_t ret = IRQ_NONE;
/* clear the interrupt */
tstat = IMX_TSTAT(TIMER_BASE);
IMX_TSTAT(TIMER_BASE) = 0;
if (tstat & TSTAT_COMP) {
evt->event_handler(evt);
ret = IRQ_HANDLED;
}
return ret;
}
static struct irqaction imx_timer_irq = {
.name = "i.MX Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = imx_timer_interrupt,
};
/*
* Set up timer hardware into expected mode and state.
*/
static void __init imx_timer_hardware_init(void)
{
/*
* Initialise to a known state (all timers off, and timing reset)
*/
IMX_TCTL(TIMER_BASE) = 0;
IMX_TPRER(TIMER_BASE) = 0;
IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_TEN;
}
cycle_t imx_get_cycles(struct clocksource *cs)
{
return IMX_TCN(TIMER_BASE);
}
static struct clocksource clocksource_imx = {
.name = "imx_timer1",
.rating = 200,
.read = imx_get_cycles,
.mask = 0xFFFFFFFF,
.shift = 20,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static int __init imx_clocksource_init(unsigned long rate)
{
clocksource_imx.mult =
clocksource_hz2mult(rate, clocksource_imx.shift);
clocksource_register(&clocksource_imx);
return 0;
}
static int imx_set_next_event(unsigned long evt,
struct clock_event_device *unused)
{
unsigned long tcmp;
tcmp = IMX_TCN(TIMER_BASE) + evt;
IMX_TCMP(TIMER_BASE) = tcmp;
return (int32_t)(tcmp - IMX_TCN(TIMER_BASE)) < 0 ? -ETIME : 0;
}
#ifdef DEBUG
static const char *clock_event_mode_label[]={
[CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC",
[CLOCK_EVT_MODE_ONESHOT] = "CLOCK_EVT_MODE_ONESHOT",
[CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN",
[CLOCK_EVT_MODE_UNUSED] = "CLOCK_EVT_MODE_UNUSED"
};
#endif /*DEBUG*/
static void imx_set_mode(enum clock_event_mode mode, struct clock_event_device *evt)
{
unsigned long flags;
/*
* The timer interrupt generation is disabled at least
* for enough time to call imx_set_next_event()
*/
local_irq_save(flags);
/* Disable interrupt in GPT module */
IMX_TCTL(TIMER_BASE) &= ~TCTL_IRQEN;
if (mode != clockevent_mode) {
/* Set event time into far-far future */
IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) - 3;
/* Clear pending interrupt */
IMX_TSTAT(TIMER_BASE) &= ~TSTAT_COMP;
}
#ifdef DEBUG
printk(KERN_INFO "imx_set_mode: changing mode from %s to %s\n",
clock_event_mode_label[clockevent_mode], clock_event_mode_label[mode]);
#endif /*DEBUG*/
/* Remember timer mode */
clockevent_mode = mode;
local_irq_restore(flags);
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
printk(KERN_ERR "imx_set_mode: Periodic mode is not supported for i.MX\n");
break;
case CLOCK_EVT_MODE_ONESHOT:
/*
* Do not put overhead of interrupt enable/disable into
* imx_set_next_event(), the core has about 4 minutes
* to call imx_set_next_event() or shutdown clock after
* mode switching
*/
local_irq_save(flags);
IMX_TCTL(TIMER_BASE) |= TCTL_IRQEN;
local_irq_restore(flags);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_RESUME:
/* Left event sources disabled, no more interrupts appears */
break;
}
}
static struct clock_event_device clockevent_imx = {
.name = "imx_timer1",
.features = CLOCK_EVT_FEAT_ONESHOT,
.shift = 32,
.set_mode = imx_set_mode,
.set_next_event = imx_set_next_event,
.rating = 200,
};
static int __init imx_clockevent_init(unsigned long rate)
{
clockevent_imx.mult = div_sc(rate, NSEC_PER_SEC,
clockevent_imx.shift);
clockevent_imx.max_delta_ns =
clockevent_delta2ns(0xfffffffe, &clockevent_imx);
clockevent_imx.min_delta_ns =
clockevent_delta2ns(0xf, &clockevent_imx);
clockevent_imx.cpumask = cpumask_of(0);
clockevents_register_device(&clockevent_imx);
return 0;
}
extern int imx_clocks_init(void);
static void __init imx_timer_init(void)
{
struct clk *clk;
unsigned long rate;
imx_clocks_init();
clk = clk_get(NULL, "perclk1");
clk_enable(clk);
rate = clk_get_rate(clk);
imx_timer_hardware_init();
imx_clocksource_init(rate);
imx_clockevent_init(rate);
/*
* Make irqs happen for the system timer
*/
setup_irq(TIM1_INT, &imx_timer_irq);
}
struct sys_timer imx_timer = {
.init = imx_timer_init,
};
|
