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Alexey Charkov21f47fb2010-12-23 13:11:21 +01001/*
Tony Prisk83cc7692012-10-06 19:55:42 +13002 * arch/arm/mach-vt8500/timer.c
Alexey Charkov21f47fb2010-12-23 13:11:21 +01003 *
Tony Priske9a91de2012-08-03 21:00:06 +12004 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
Alexey Charkov21f47fb2010-12-23 13:11:21 +01005 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21
Tony Priske9a91de2012-08-03 21:00:06 +120022/*
23 * This file is copied and modified from the original timer.c provided by
24 * Alexey Charkov. Minor changes have been made for Device Tree Support.
25 */
26
Alexey Charkov21f47fb2010-12-23 13:11:21 +010027#include <linux/io.h>
28#include <linux/irq.h>
29#include <linux/interrupt.h>
30#include <linux/clocksource.h>
31#include <linux/clockchips.h>
32#include <linux/delay.h>
Alexey Charkov21f47fb2010-12-23 13:11:21 +010033
Tony Priske9a91de2012-08-03 21:00:06 +120034#include <linux/of.h>
35#include <linux/of_address.h>
36#include <linux/of_irq.h>
Alexey Charkov21f47fb2010-12-23 13:11:21 +010037
38#define VT8500_TIMER_OFFSET 0x0100
Tony Priske9a91de2012-08-03 21:00:06 +120039#define VT8500_TIMER_HZ 3000000
Alexey Charkov21f47fb2010-12-23 13:11:21 +010040#define TIMER_MATCH_VAL 0x0000
41#define TIMER_COUNT_VAL 0x0010
42#define TIMER_STATUS_VAL 0x0014
43#define TIMER_IER_VAL 0x001c /* interrupt enable */
44#define TIMER_CTRL_VAL 0x0020
45#define TIMER_AS_VAL 0x0024 /* access status */
46#define TIMER_COUNT_R_ACTIVE (1 << 5) /* not ready for read */
47#define TIMER_COUNT_W_ACTIVE (1 << 4) /* not ready for write */
48#define TIMER_MATCH_W_ACTIVE (1 << 0) /* not ready for write */
Alexey Charkov21f47fb2010-12-23 13:11:21 +010049
50#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
51
Roman Volkovf9eccf22016-01-01 16:24:41 +030052#define MIN_OSCR_DELTA 16
53
Alexey Charkov21f47fb2010-12-23 13:11:21 +010054static void __iomem *regbase;
55
56static cycle_t vt8500_timer_read(struct clocksource *cs)
57{
58 int loops = msecs_to_loops(10);
59 writel(3, regbase + TIMER_CTRL_VAL);
60 while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE)
61 && --loops)
62 cpu_relax();
63 return readl(regbase + TIMER_COUNT_VAL);
64}
65
Tony Priske9a91de2012-08-03 21:00:06 +120066static struct clocksource clocksource = {
Alexey Charkov21f47fb2010-12-23 13:11:21 +010067 .name = "vt8500_timer",
68 .rating = 200,
69 .read = vt8500_timer_read,
70 .mask = CLOCKSOURCE_MASK(32),
71 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
72};
73
74static int vt8500_timer_set_next_event(unsigned long cycles,
75 struct clock_event_device *evt)
76{
77 int loops = msecs_to_loops(10);
78 cycle_t alarm = clocksource.read(&clocksource) + cycles;
79 while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE)
80 && --loops)
81 cpu_relax();
82 writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL);
83
Roman Volkovf9eccf22016-01-01 16:24:41 +030084 if ((signed)(alarm - clocksource.read(&clocksource)) <= MIN_OSCR_DELTA)
Alexey Charkov21f47fb2010-12-23 13:11:21 +010085 return -ETIME;
86
87 writel(1, regbase + TIMER_IER_VAL);
88
89 return 0;
90}
91
Viresh Kumar214bc752015-06-18 16:24:54 +053092static int vt8500_shutdown(struct clock_event_device *evt)
Alexey Charkov21f47fb2010-12-23 13:11:21 +010093{
Viresh Kumar214bc752015-06-18 16:24:54 +053094 writel(readl(regbase + TIMER_CTRL_VAL) | 1, regbase + TIMER_CTRL_VAL);
95 writel(0, regbase + TIMER_IER_VAL);
96 return 0;
Alexey Charkov21f47fb2010-12-23 13:11:21 +010097}
98
Tony Priske9a91de2012-08-03 21:00:06 +120099static struct clock_event_device clockevent = {
Viresh Kumar214bc752015-06-18 16:24:54 +0530100 .name = "vt8500_timer",
101 .features = CLOCK_EVT_FEAT_ONESHOT,
102 .rating = 200,
103 .set_next_event = vt8500_timer_set_next_event,
104 .set_state_shutdown = vt8500_shutdown,
105 .set_state_oneshot = vt8500_shutdown,
Alexey Charkov21f47fb2010-12-23 13:11:21 +0100106};
107
108static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)
109{
110 struct clock_event_device *evt = dev_id;
111 writel(0xf, regbase + TIMER_STATUS_VAL);
112 evt->event_handler(evt);
113
114 return IRQ_HANDLED;
115}
116
Tony Priske9a91de2012-08-03 21:00:06 +1200117static struct irqaction irq = {
Alexey Charkov21f47fb2010-12-23 13:11:21 +0100118 .name = "vt8500_timer",
Michael Opdenacker39039eb2013-12-09 10:38:50 +0100119 .flags = IRQF_TIMER | IRQF_IRQPOLL,
Alexey Charkov21f47fb2010-12-23 13:11:21 +0100120 .handler = vt8500_timer_interrupt,
121 .dev_id = &clockevent,
122};
123
Rob Herringeffbfdd2013-02-06 14:40:22 -0600124static void __init vt8500_timer_init(struct device_node *np)
Alexey Charkov21f47fb2010-12-23 13:11:21 +0100125{
Tony Priske9a91de2012-08-03 21:00:06 +1200126 int timer_irq;
127
Tony Priske9a91de2012-08-03 21:00:06 +1200128 regbase = of_iomap(np, 0);
129 if (!regbase) {
130 pr_err("%s: Missing iobase description in Device Tree\n",
131 __func__);
Tony Priske9a91de2012-08-03 21:00:06 +1200132 return;
133 }
134 timer_irq = irq_of_parse_and_map(np, 0);
135 if (!timer_irq) {
136 pr_err("%s: Missing irq description in Device Tree\n",
137 __func__);
Tony Priske9a91de2012-08-03 21:00:06 +1200138 return;
139 }
Alexey Charkov21f47fb2010-12-23 13:11:21 +0100140
141 writel(1, regbase + TIMER_CTRL_VAL);
142 writel(0xf, regbase + TIMER_STATUS_VAL);
143 writel(~0, regbase + TIMER_MATCH_VAL);
144
145 if (clocksource_register_hz(&clocksource, VT8500_TIMER_HZ))
Tony Priske9a91de2012-08-03 21:00:06 +1200146 pr_err("%s: vt8500_timer_init: clocksource_register failed for %s\n",
147 __func__, clocksource.name);
Alexey Charkov21f47fb2010-12-23 13:11:21 +0100148
Alexey Charkov21f47fb2010-12-23 13:11:21 +0100149 clockevent.cpumask = cpumask_of(0);
150
Tony Priske9a91de2012-08-03 21:00:06 +1200151 if (setup_irq(timer_irq, &irq))
152 pr_err("%s: setup_irq failed for %s\n", __func__,
153 clockevent.name);
Shawn Guo838a2ae2013-01-12 11:50:05 +0000154 clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ,
Roman Volkovf9eccf22016-01-01 16:24:41 +0300155 MIN_OSCR_DELTA * 2, 0xf0000000);
Alexey Charkov21f47fb2010-12-23 13:11:21 +0100156}
157
Arnd Bergmann3d5a9652013-03-19 15:38:50 +0100158CLOCKSOURCE_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init);