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Sascha Hauerf2b89012010-08-19 14:08:04 +02001/*
2 * linux/arch/arm/plat-mxc/epit.c
3 *
4 * Copyright (C) 2010 Sascha Hauer <s.hauer@pengutronix.de>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version 2
9 * of the License, or (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
18 * MA 02110-1301, USA.
19 */
20
21#define EPITCR 0x00
22#define EPITSR 0x04
23#define EPITLR 0x08
24#define EPITCMPR 0x0c
25#define EPITCNR 0x10
26
27#define EPITCR_EN (1 << 0)
28#define EPITCR_ENMOD (1 << 1)
29#define EPITCR_OCIEN (1 << 2)
30#define EPITCR_RLD (1 << 3)
31#define EPITCR_PRESC(x) (((x) & 0xfff) << 4)
32#define EPITCR_SWR (1 << 16)
33#define EPITCR_IOVW (1 << 17)
34#define EPITCR_DBGEN (1 << 18)
35#define EPITCR_WAITEN (1 << 19)
36#define EPITCR_RES (1 << 20)
37#define EPITCR_STOPEN (1 << 21)
38#define EPITCR_OM_DISCON (0 << 22)
39#define EPITCR_OM_TOGGLE (1 << 22)
40#define EPITCR_OM_CLEAR (2 << 22)
41#define EPITCR_OM_SET (3 << 22)
42#define EPITCR_CLKSRC_OFF (0 << 24)
43#define EPITCR_CLKSRC_PERIPHERAL (1 << 24)
44#define EPITCR_CLKSRC_REF_HIGH (1 << 24)
45#define EPITCR_CLKSRC_REF_LOW (3 << 24)
46
47#define EPITSR_OCIF (1 << 0)
48
49#include <linux/interrupt.h>
50#include <linux/irq.h>
51#include <linux/clockchips.h>
52#include <linux/clk.h>
Sascha Hauer2cfb4512012-05-16 12:29:53 +020053#include <linux/err.h>
Sascha Hauerf2b89012010-08-19 14:08:04 +020054#include <asm/mach/time.h>
Shawn Guoe3372472012-09-13 21:01:00 +080055
56#include "common.h"
Shawn Guo50f2de62012-09-14 14:14:45 +080057#include "hardware.h"
Sascha Hauerf2b89012010-08-19 14:08:04 +020058
59static struct clock_event_device clockevent_epit;
60static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
61
62static void __iomem *timer_base;
63
64static inline void epit_irq_disable(void)
65{
66 u32 val;
67
68 val = __raw_readl(timer_base + EPITCR);
69 val &= ~EPITCR_OCIEN;
70 __raw_writel(val, timer_base + EPITCR);
71}
72
73static inline void epit_irq_enable(void)
74{
75 u32 val;
76
77 val = __raw_readl(timer_base + EPITCR);
78 val |= EPITCR_OCIEN;
79 __raw_writel(val, timer_base + EPITCR);
80}
81
82static void epit_irq_acknowledge(void)
83{
84 __raw_writel(EPITSR_OCIF, timer_base + EPITSR);
85}
86
Sascha Hauerf2b89012010-08-19 14:08:04 +020087static int __init epit_clocksource_init(struct clk *timer_clk)
88{
89 unsigned int c = clk_get_rate(timer_clk);
90
Russell Kingbfe45e02011-05-08 15:33:30 +010091 return clocksource_mmio_init(timer_base + EPITCNR, "epit", c, 200, 32,
92 clocksource_mmio_readl_down);
Sascha Hauerf2b89012010-08-19 14:08:04 +020093}
94
95/* clock event */
96
97static int epit_set_next_event(unsigned long evt,
98 struct clock_event_device *unused)
99{
100 unsigned long tcmp;
101
102 tcmp = __raw_readl(timer_base + EPITCNR);
103
104 __raw_writel(tcmp - evt, timer_base + EPITCMPR);
105
106 return 0;
107}
108
109static void epit_set_mode(enum clock_event_mode mode,
110 struct clock_event_device *evt)
111{
112 unsigned long flags;
113
114 /*
115 * The timer interrupt generation is disabled at least
116 * for enough time to call epit_set_next_event()
117 */
118 local_irq_save(flags);
119
120 /* Disable interrupt in GPT module */
121 epit_irq_disable();
122
123 if (mode != clockevent_mode) {
124 /* Set event time into far-far future */
125
126 /* Clear pending interrupt */
127 epit_irq_acknowledge();
128 }
129
130 /* Remember timer mode */
131 clockevent_mode = mode;
132 local_irq_restore(flags);
133
134 switch (mode) {
135 case CLOCK_EVT_MODE_PERIODIC:
136 printk(KERN_ERR "epit_set_mode: Periodic mode is not "
137 "supported for i.MX EPIT\n");
138 break;
139 case CLOCK_EVT_MODE_ONESHOT:
140 /*
141 * Do not put overhead of interrupt enable/disable into
142 * epit_set_next_event(), the core has about 4 minutes
143 * to call epit_set_next_event() or shutdown clock after
144 * mode switching
145 */
146 local_irq_save(flags);
147 epit_irq_enable();
148 local_irq_restore(flags);
149 break;
150 case CLOCK_EVT_MODE_SHUTDOWN:
151 case CLOCK_EVT_MODE_UNUSED:
152 case CLOCK_EVT_MODE_RESUME:
153 /* Left event sources disabled, no more interrupts appear */
154 break;
155 }
156}
157
158/*
159 * IRQ handler for the timer
160 */
161static irqreturn_t epit_timer_interrupt(int irq, void *dev_id)
162{
163 struct clock_event_device *evt = &clockevent_epit;
164
165 epit_irq_acknowledge();
166
167 evt->event_handler(evt);
168
169 return IRQ_HANDLED;
170}
171
172static struct irqaction epit_timer_irq = {
173 .name = "i.MX EPIT Timer Tick",
174 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
175 .handler = epit_timer_interrupt,
176};
177
178static struct clock_event_device clockevent_epit = {
179 .name = "epit",
180 .features = CLOCK_EVT_FEAT_ONESHOT,
Sascha Hauerf2b89012010-08-19 14:08:04 +0200181 .set_mode = epit_set_mode,
182 .set_next_event = epit_set_next_event,
183 .rating = 200,
184};
185
186static int __init epit_clockevent_init(struct clk *timer_clk)
187{
Sascha Hauerf2b89012010-08-19 14:08:04 +0200188 clockevent_epit.cpumask = cpumask_of(0);
Shawn Guo838a2ae2013-01-12 11:50:05 +0000189 clockevents_config_and_register(&clockevent_epit,
190 clk_get_rate(timer_clk),
191 0x800, 0xfffffffe);
Sascha Hauerf2b89012010-08-19 14:08:04 +0200192
193 return 0;
194}
195
Sascha Hauer2cfb4512012-05-16 12:29:53 +0200196void __init epit_timer_init(void __iomem *base, int irq)
Sascha Hauerf2b89012010-08-19 14:08:04 +0200197{
Sascha Hauer2cfb4512012-05-16 12:29:53 +0200198 struct clk *timer_clk;
199
200 timer_clk = clk_get_sys("imx-epit.0", NULL);
201 if (IS_ERR(timer_clk)) {
202 pr_err("i.MX epit: unable to get clk\n");
203 return;
204 }
205
Richard Zhao8f33eed2011-11-15 14:48:00 +0800206 clk_prepare_enable(timer_clk);
Sascha Hauerf2b89012010-08-19 14:08:04 +0200207
208 timer_base = base;
209
210 /*
211 * Initialise to a known state (all timers off, and timing reset)
212 */
213 __raw_writel(0x0, timer_base + EPITCR);
214
215 __raw_writel(0xffffffff, timer_base + EPITLR);
216 __raw_writel(EPITCR_EN | EPITCR_CLKSRC_REF_HIGH | EPITCR_WAITEN,
217 timer_base + EPITCR);
218
219 /* init and register the timer to the framework */
220 epit_clocksource_init(timer_clk);
221 epit_clockevent_init(timer_clk);
222
223 /* Make irqs happen */
224 setup_irq(irq, &epit_timer_irq);
225}