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/*
* arch/arm/mach-vt8500/timer.c
*
* Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/delay.h>
#include <asm/mach/time.h>
#include "devices.h"
#define VT8500_TIMER_OFFSET 0x0100
#define TIMER_MATCH_VAL 0x0000
#define TIMER_COUNT_VAL 0x0010
#define TIMER_STATUS_VAL 0x0014
#define TIMER_IER_VAL 0x001c /* interrupt enable */
#define TIMER_CTRL_VAL 0x0020
#define TIMER_AS_VAL 0x0024 /* access status */
#define TIMER_COUNT_R_ACTIVE (1 << 5) /* not ready for read */
#define TIMER_COUNT_W_ACTIVE (1 << 4) /* not ready for write */
#define TIMER_MATCH_W_ACTIVE (1 << 0) /* not ready for write */
#define VT8500_TIMER_HZ 3000000
#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
static void __iomem *regbase;
static cycle_t vt8500_timer_read(struct clocksource *cs)
{
int loops = msecs_to_loops(10);
writel(3, regbase + TIMER_CTRL_VAL);
while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE)
&& --loops)
cpu_relax();
return readl(regbase + TIMER_COUNT_VAL);
}
struct clocksource clocksource = {
.name = "vt8500_timer",
.rating = 200,
.read = vt8500_timer_read,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static int vt8500_timer_set_next_event(unsigned long cycles,
struct clock_event_device *evt)
{
int loops = msecs_to_loops(10);
cycle_t alarm = clocksource.read(&clocksource) + cycles;
while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE)
&& --loops)
cpu_relax();
writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL);
if ((signed)(alarm - clocksource.read(&clocksource)) <= 16)
return -ETIME;
writel(1, regbase + TIMER_IER_VAL);
return 0;
}
static void vt8500_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
switch (mode) {
case CLOCK_EVT_MODE_RESUME:
case CLOCK_EVT_MODE_PERIODIC:
break;
case CLOCK_EVT_MODE_ONESHOT:
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
writel(readl(regbase + TIMER_CTRL_VAL) | 1,
regbase + TIMER_CTRL_VAL);
writel(0, regbase + TIMER_IER_VAL);
break;
}
}
struct clock_event_device clockevent = {
.name = "vt8500_timer",
.features = CLOCK_EVT_FEAT_ONESHOT,
.rating = 200,
.set_next_event = vt8500_timer_set_next_event,
.set_mode = vt8500_timer_set_mode,
};
static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
writel(0xf, regbase + TIMER_STATUS_VAL);
evt->event_handler(evt);
return IRQ_HANDLED;
}
struct irqaction irq = {
.name = "vt8500_timer",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = vt8500_timer_interrupt,
.dev_id = &clockevent,
};
static void __init vt8500_timer_init(void)
{
regbase = ioremap(wmt_pmc_base + VT8500_TIMER_OFFSET, 0x28);
if (!regbase)
printk(KERN_ERR "vt8500_timer_init: failed to map MMIO registers\n");
writel(1, regbase + TIMER_CTRL_VAL);
writel(0xf, regbase + TIMER_STATUS_VAL);
writel(~0, regbase + TIMER_MATCH_VAL);
if (clocksource_register_hz(&clocksource, VT8500_TIMER_HZ))
printk(KERN_ERR "vt8500_timer_init: clocksource_register failed for %s\n",
clocksource.name);
clockevents_calc_mult_shift(&clockevent, VT8500_TIMER_HZ, 4);
/* copy-pasted from mach-msm; no idea */
clockevent.max_delta_ns =
clockevent_delta2ns(0xf0000000, &clockevent);
clockevent.min_delta_ns = clockevent_delta2ns(4, &clockevent);
clockevent.cpumask = cpumask_of(0);
if (setup_irq(wmt_timer_irq, &irq))
printk(KERN_ERR "vt8500_timer_init: setup_irq failed for %s\n",
clockevent.name);
clockevents_register_device(&clockevent);
}
struct sys_timer vt8500_timer = {
.init = vt8500_timer_init
};
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