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
221
222
223
224
225
|
/*
* linux/arch/arm/plat-mxc/epit.c
*
* Copyright (C) 2010 Sascha Hauer <s.hauer@pengutronix.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#define EPITCR 0x00
#define EPITSR 0x04
#define EPITLR 0x08
#define EPITCMPR 0x0c
#define EPITCNR 0x10
#define EPITCR_EN (1 << 0)
#define EPITCR_ENMOD (1 << 1)
#define EPITCR_OCIEN (1 << 2)
#define EPITCR_RLD (1 << 3)
#define EPITCR_PRESC(x) (((x) & 0xfff) << 4)
#define EPITCR_SWR (1 << 16)
#define EPITCR_IOVW (1 << 17)
#define EPITCR_DBGEN (1 << 18)
#define EPITCR_WAITEN (1 << 19)
#define EPITCR_RES (1 << 20)
#define EPITCR_STOPEN (1 << 21)
#define EPITCR_OM_DISCON (0 << 22)
#define EPITCR_OM_TOGGLE (1 << 22)
#define EPITCR_OM_CLEAR (2 << 22)
#define EPITCR_OM_SET (3 << 22)
#define EPITCR_CLKSRC_OFF (0 << 24)
#define EPITCR_CLKSRC_PERIPHERAL (1 << 24)
#define EPITCR_CLKSRC_REF_HIGH (1 << 24)
#define EPITCR_CLKSRC_REF_LOW (3 << 24)
#define EPITSR_OCIF (1 << 0)
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/clockchips.h>
#include <linux/clk.h>
#include <mach/hardware.h>
#include <asm/mach/time.h>
#include <mach/common.h>
static struct clock_event_device clockevent_epit;
static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
static void __iomem *timer_base;
static inline void epit_irq_disable(void)
{
u32 val;
val = __raw_readl(timer_base + EPITCR);
val &= ~EPITCR_OCIEN;
__raw_writel(val, timer_base + EPITCR);
}
static inline void epit_irq_enable(void)
{
u32 val;
val = __raw_readl(timer_base + EPITCR);
val |= EPITCR_OCIEN;
__raw_writel(val, timer_base + EPITCR);
}
static void epit_irq_acknowledge(void)
{
__raw_writel(EPITSR_OCIF, timer_base + EPITSR);
}
static int __init epit_clocksource_init(struct clk *timer_clk)
{
unsigned int c = clk_get_rate(timer_clk);
return clocksource_mmio_init(timer_base + EPITCNR, "epit", c, 200, 32,
clocksource_mmio_readl_down);
}
/* clock event */
static int epit_set_next_event(unsigned long evt,
struct clock_event_device *unused)
{
unsigned long tcmp;
tcmp = __raw_readl(timer_base + EPITCNR);
__raw_writel(tcmp - evt, timer_base + EPITCMPR);
return 0;
}
static void epit_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 epit_set_next_event()
*/
local_irq_save(flags);
/* Disable interrupt in GPT module */
epit_irq_disable();
if (mode != clockevent_mode) {
/* Set event time into far-far future */
/* Clear pending interrupt */
epit_irq_acknowledge();
}
/* Remember timer mode */
clockevent_mode = mode;
local_irq_restore(flags);
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
printk(KERN_ERR "epit_set_mode: Periodic mode is not "
"supported for i.MX EPIT\n");
break;
case CLOCK_EVT_MODE_ONESHOT:
/*
* Do not put overhead of interrupt enable/disable into
* epit_set_next_event(), the core has about 4 minutes
* to call epit_set_next_event() or shutdown clock after
* mode switching
*/
local_irq_save(flags);
epit_irq_enable();
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 appear */
break;
}
}
/*
* IRQ handler for the timer
*/
static irqreturn_t epit_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &clockevent_epit;
epit_irq_acknowledge();
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction epit_timer_irq = {
.name = "i.MX EPIT Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = epit_timer_interrupt,
};
static struct clock_event_device clockevent_epit = {
.name = "epit",
.features = CLOCK_EVT_FEAT_ONESHOT,
.shift = 32,
.set_mode = epit_set_mode,
.set_next_event = epit_set_next_event,
.rating = 200,
};
static int __init epit_clockevent_init(struct clk *timer_clk)
{
unsigned int c = clk_get_rate(timer_clk);
clockevent_epit.mult = div_sc(c, NSEC_PER_SEC,
clockevent_epit.shift);
clockevent_epit.max_delta_ns =
clockevent_delta2ns(0xfffffffe, &clockevent_epit);
clockevent_epit.min_delta_ns =
clockevent_delta2ns(0x800, &clockevent_epit);
clockevent_epit.cpumask = cpumask_of(0);
clockevents_register_device(&clockevent_epit);
return 0;
}
void __init epit_timer_init(struct clk *timer_clk, void __iomem *base, int irq)
{
clk_prepare_enable(timer_clk);
timer_base = base;
/*
* Initialise to a known state (all timers off, and timing reset)
*/
__raw_writel(0x0, timer_base + EPITCR);
__raw_writel(0xffffffff, timer_base + EPITLR);
__raw_writel(EPITCR_EN | EPITCR_CLKSRC_REF_HIGH | EPITCR_WAITEN,
timer_base + EPITCR);
/* init and register the timer to the framework */
epit_clocksource_init(timer_clk);
epit_clockevent_init(timer_clk);
/* Make irqs happen */
setup_irq(irq, &epit_timer_irq);
}
|
