1 /*
2 * arch/arm/mach-vt8500/timer.c
3 *
4 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21 #include <linux/io.h>
22 #include <linux/irq.h>
23 #include <linux/interrupt.h>
24 #include <linux/clocksource.h>
25 #include <linux/clockchips.h>
26 #include <linux/delay.h>
27
28 #include <asm/mach/time.h>
29
30 #include "devices.h"
31
32 #define VT8500_TIMER_OFFSET 0x0100
33 #define TIMER_MATCH_VAL 0x0000
34 #define TIMER_COUNT_VAL 0x0010
35 #define TIMER_STATUS_VAL 0x0014
36 #define TIMER_IER_VAL 0x001c /* interrupt enable */
37 #define TIMER_CTRL_VAL 0x0020
38 #define TIMER_AS_VAL 0x0024 /* access status */
39 #define TIMER_COUNT_R_ACTIVE (1 << 5) /* not ready for read */
40 #define TIMER_COUNT_W_ACTIVE (1 << 4) /* not ready for write */
41 #define TIMER_MATCH_W_ACTIVE (1 << 0) /* not ready for write */
42 #define VT8500_TIMER_HZ 3000000
43
44 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
45
46 static void __iomem *regbase;
47
vt8500_timer_read(struct clocksource * cs)48 static cycle_t vt8500_timer_read(struct clocksource *cs)
49 {
50 int loops = msecs_to_loops(10);
51 writel(3, regbase + TIMER_CTRL_VAL);
52 while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE)
53 && --loops)
54 cpu_relax();
55 return readl(regbase + TIMER_COUNT_VAL);
56 }
57
58 struct clocksource clocksource = {
59 .name = "vt8500_timer",
60 .rating = 200,
61 .read = vt8500_timer_read,
62 .mask = CLOCKSOURCE_MASK(32),
63 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
64 };
65
vt8500_timer_set_next_event(unsigned long cycles,struct clock_event_device * evt)66 static int vt8500_timer_set_next_event(unsigned long cycles,
67 struct clock_event_device *evt)
68 {
69 int loops = msecs_to_loops(10);
70 cycle_t alarm = clocksource.read(&clocksource) + cycles;
71 while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE)
72 && --loops)
73 cpu_relax();
74 writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL);
75
76 if ((signed)(alarm - clocksource.read(&clocksource)) <= 16)
77 return -ETIME;
78
79 writel(1, regbase + TIMER_IER_VAL);
80
81 return 0;
82 }
83
vt8500_timer_set_mode(enum clock_event_mode mode,struct clock_event_device * evt)84 static void vt8500_timer_set_mode(enum clock_event_mode mode,
85 struct clock_event_device *evt)
86 {
87 switch (mode) {
88 case CLOCK_EVT_MODE_RESUME:
89 case CLOCK_EVT_MODE_PERIODIC:
90 break;
91 case CLOCK_EVT_MODE_ONESHOT:
92 case CLOCK_EVT_MODE_UNUSED:
93 case CLOCK_EVT_MODE_SHUTDOWN:
94 writel(readl(regbase + TIMER_CTRL_VAL) | 1,
95 regbase + TIMER_CTRL_VAL);
96 writel(0, regbase + TIMER_IER_VAL);
97 break;
98 }
99 }
100
101 struct clock_event_device clockevent = {
102 .name = "vt8500_timer",
103 .features = CLOCK_EVT_FEAT_ONESHOT,
104 .rating = 200,
105 .set_next_event = vt8500_timer_set_next_event,
106 .set_mode = vt8500_timer_set_mode,
107 };
108
vt8500_timer_interrupt(int irq,void * dev_id)109 static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)
110 {
111 struct clock_event_device *evt = dev_id;
112 writel(0xf, regbase + TIMER_STATUS_VAL);
113 evt->event_handler(evt);
114
115 return IRQ_HANDLED;
116 }
117
118 struct irqaction irq = {
119 .name = "vt8500_timer",
120 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
121 .handler = vt8500_timer_interrupt,
122 .dev_id = &clockevent,
123 };
124
vt8500_timer_init(void)125 static void __init vt8500_timer_init(void)
126 {
127 regbase = ioremap(wmt_pmc_base + VT8500_TIMER_OFFSET, 0x28);
128 if (!regbase)
129 printk(KERN_ERR "vt8500_timer_init: failed to map MMIO registers\n");
130
131 writel(1, regbase + TIMER_CTRL_VAL);
132 writel(0xf, regbase + TIMER_STATUS_VAL);
133 writel(~0, regbase + TIMER_MATCH_VAL);
134
135 if (clocksource_register_hz(&clocksource, VT8500_TIMER_HZ))
136 printk(KERN_ERR "vt8500_timer_init: clocksource_register failed for %s\n",
137 clocksource.name);
138
139 clockevents_calc_mult_shift(&clockevent, VT8500_TIMER_HZ, 4);
140
141 /* copy-pasted from mach-msm; no idea */
142 clockevent.max_delta_ns =
143 clockevent_delta2ns(0xf0000000, &clockevent);
144 clockevent.min_delta_ns = clockevent_delta2ns(4, &clockevent);
145 clockevent.cpumask = cpumask_of(0);
146
147 if (setup_irq(wmt_timer_irq, &irq))
148 printk(KERN_ERR "vt8500_timer_init: setup_irq failed for %s\n",
149 clockevent.name);
150 clockevents_register_device(&clockevent);
151 }
152
153 struct sys_timer vt8500_timer = {
154 .init = vt8500_timer_init
155 };
156