1 /*
2 * linux/arch/arm/mach-imx/time.c
3 *
4 * Copyright (C) 2000-2001 Deep Blue Solutions
5 * Copyright (C) 2002 Shane Nay (shane@minirl.com)
6 * Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com)
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12 #include <linux/kernel.h>
13 #include <linux/sched.h>
14 #include <linux/init.h>
15 #include <linux/interrupt.h>
16 #include <linux/irq.h>
17 #include <linux/time.h>
18 #include <linux/clocksource.h>
19 #include <linux/clockchips.h>
20
21 #include <asm/hardware.h>
22 #include <asm/io.h>
23 #include <asm/leds.h>
24 #include <asm/irq.h>
25 #include <asm/mach/time.h>
26
27 /* Use timer 1 as system timer */
28 #define TIMER_BASE IMX_TIM1_BASE
29
30 static struct clock_event_device clockevent_imx;
31 static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
32
33 /*
34 * IRQ handler for the timer
35 */
36 static irqreturn_t
37 imx_timer_interrupt(int irq, void *dev_id)
38 {
39 struct clock_event_device *evt = &clockevent_imx;
40 uint32_t tstat;
41 irqreturn_t ret = IRQ_NONE;
42
43 /* clear the interrupt */
44 tstat = IMX_TSTAT(TIMER_BASE);
45 IMX_TSTAT(TIMER_BASE) = 0;
46
47 if (tstat & TSTAT_COMP) {
48 evt->event_handler(evt);
49 ret = IRQ_HANDLED;
50 }
51
52 return ret;
53 }
54
55 static struct irqaction imx_timer_irq = {
56 .name = "i.MX Timer Tick",
57 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
58 .handler = imx_timer_interrupt,
59 };
60
61 /*
62 * Set up timer hardware into expected mode and state.
63 */
64 static void __init imx_timer_hardware_init(void)
65 {
66 /*
67 * Initialise to a known state (all timers off, and timing reset)
68 */
69 IMX_TCTL(TIMER_BASE) = 0;
70 IMX_TPRER(TIMER_BASE) = 0;
71
72 IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_TEN;
73 }
74
75 cycle_t imx_get_cycles(void)
76 {
77 return IMX_TCN(TIMER_BASE);
78 }
79
80 static struct clocksource clocksource_imx = {
81 .name = "imx_timer1",
82 .rating = 200,
83 .read = imx_get_cycles,
84 .mask = 0xFFFFFFFF,
85 .shift = 20,
86 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
87 };
88
89 static int __init imx_clocksource_init(void)
90 {
91 clocksource_imx.mult =
92 clocksource_hz2mult(imx_get_perclk1(), clocksource_imx.shift);
93 clocksource_register(&clocksource_imx);
94
95 return 0;
96 }
97
98 static int imx_set_next_event(unsigned long evt,
99 struct clock_event_device *unused)
100 {
101 unsigned long tcmp;
102
103 tcmp = IMX_TCN(TIMER_BASE) + evt;
104 IMX_TCMP(TIMER_BASE) = tcmp;
105
106 return (int32_t)(tcmp - IMX_TCN(TIMER_BASE)) < 0 ? -ETIME : 0;
107 }
108
109 #ifdef DEBUG
110 static const char *clock_event_mode_label[]={
111 [CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC",
112 [CLOCK_EVT_MODE_ONESHOT] = "CLOCK_EVT_MODE_ONESHOT",
113 [CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN",
114 [CLOCK_EVT_MODE_UNUSED] = "CLOCK_EVT_MODE_UNUSED"
115 };
116 #endif /*DEBUG*/
117
118 static void imx_set_mode(enum clock_event_mode mode, struct clock_event_device *evt)
119 {
120 unsigned long flags;
121
122 /*
123 * The timer interrupt generation is disabled at least
124 * for enough time to call imx_set_next_event()
125 */
126 local_irq_save(flags);
127 /* Disable interrupt in GPT module */
128 IMX_TCTL(TIMER_BASE) &= ~TCTL_IRQEN;
129 if (mode != clockevent_mode) {
130 /* Set event time into far-far future */
131 IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) - 3;
132 /* Clear pending interrupt */
133 IMX_TSTAT(TIMER_BASE) &= ~TSTAT_COMP;
134 }
135
136 #ifdef DEBUG
137 printk(KERN_INFO "imx_set_mode: changing mode from %s to %s\n",
138 clock_event_mode_label[clockevent_mode], clock_event_mode_label[mode]);
139 #endif /*DEBUG*/
140
141 /* Remember timer mode */
142 clockevent_mode = mode;
143 local_irq_restore(flags);
144
145 switch (mode) {
146 case CLOCK_EVT_MODE_PERIODIC:
147 printk(KERN_ERR "imx_set_mode: Periodic mode is not supported for i.MX\n");
148 break;
149 case CLOCK_EVT_MODE_ONESHOT:
150 /*
151 * Do not put overhead of interrupt enable/disable into
152 * imx_set_next_event(), the core has about 4 minutes
153 * to call imx_set_next_event() or shutdown clock after
154 * mode switching
155 */
156 local_irq_save(flags);
157 IMX_TCTL(TIMER_BASE) |= TCTL_IRQEN;
158 local_irq_restore(flags);
159 break;
160 case CLOCK_EVT_MODE_SHUTDOWN:
161 case CLOCK_EVT_MODE_UNUSED:
162 case CLOCK_EVT_MODE_RESUME:
163 /* Left event sources disabled, no more interrupts appears */
164 break;
165 }
166 }
167
168 static struct clock_event_device clockevent_imx = {
169 .name = "imx_timer1",
170 .features = CLOCK_EVT_FEAT_ONESHOT,
171 .shift = 32,
172 .set_mode = imx_set_mode,
173 .set_next_event = imx_set_next_event,
174 .rating = 200,
175 };
176
177 static int __init imx_clockevent_init(void)
178 {
179 clockevent_imx.mult = div_sc(imx_get_perclk1(), NSEC_PER_SEC,
180 clockevent_imx.shift);
181 clockevent_imx.max_delta_ns =
182 clockevent_delta2ns(0xfffffffe, &clockevent_imx);
183 clockevent_imx.min_delta_ns =
184 clockevent_delta2ns(0xf, &clockevent_imx);
185
186 clockevent_imx.cpumask = cpumask_of_cpu(0);
187
188 clockevents_register_device(&clockevent_imx);
189
190 return 0;
191 }
192
193
194 static void __init imx_timer_init(void)
195 {
196 imx_timer_hardware_init();
197 imx_clocksource_init();
198
199 imx_clockevent_init();
200
201 /*
202 * Make irqs happen for the system timer
203 */
204 setup_irq(TIM1_INT, &imx_timer_irq);
205 }
206
207 struct sys_timer imx_timer = {
208 .init = imx_timer_init,
209 };
210
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