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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2013 by John Crispin <john@phrozen.org>
*/
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/interrupt.h>
#include <linux/reset.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <asm/mach-ralink/ralink_regs.h>
#define SYSTICK_FREQ (50 * 1000)
#define SYSTICK_CONFIG 0x00
#define SYSTICK_COMPARE 0x04
#define SYSTICK_COUNT 0x08
/* route systick irq to mips irq 7 instead of the r4k-timer */
#define CFG_EXT_STK_EN 0x2
/* enable the counter */
#define CFG_CNT_EN 0x1
struct systick_device {
void __iomem *membase;
struct clock_event_device dev;
int irq_requested;
int freq_scale;
};
static int systick_set_oneshot(struct clock_event_device *evt);
static int systick_shutdown(struct clock_event_device *evt);
static int systick_next_event(unsigned long delta,
struct clock_event_device *evt)
{
struct systick_device *sdev;
u32 count;
sdev = container_of(evt, struct systick_device, dev);
count = ioread32(sdev->membase + SYSTICK_COUNT);
count = (count + delta) % SYSTICK_FREQ;
iowrite32(count, sdev->membase + SYSTICK_COMPARE);
return 0;
}
static void systick_event_handler(struct clock_event_device *dev)
{
/* noting to do here */
}
static irqreturn_t systick_interrupt(int irq, void *dev_id)
{
struct clock_event_device *dev = (struct clock_event_device *) dev_id;
dev->event_handler(dev);
return IRQ_HANDLED;
}
static struct systick_device systick = {
.dev = {
/*
* cevt-r4k uses 300, make sure systick
* gets used if available
*/
.rating = 310,
.features = CLOCK_EVT_FEAT_ONESHOT,
.set_next_event = systick_next_event,
.set_state_shutdown = systick_shutdown,
.set_state_oneshot = systick_set_oneshot,
.event_handler = systick_event_handler,
},
};
static struct irqaction systick_irqaction = {
.handler = systick_interrupt,
.flags = IRQF_PERCPU | IRQF_TIMER,
.dev_id = &systick.dev,
};
static int systick_shutdown(struct clock_event_device *evt)
{
struct systick_device *sdev;
sdev = container_of(evt, struct systick_device, dev);
if (sdev->irq_requested)
free_irq(systick.dev.irq, &systick_irqaction);
sdev->irq_requested = 0;
iowrite32(0, systick.membase + SYSTICK_CONFIG);
return 0;
}
static int systick_set_oneshot(struct clock_event_device *evt)
{
struct systick_device *sdev;
sdev = container_of(evt, struct systick_device, dev);
if (!sdev->irq_requested)
setup_irq(systick.dev.irq, &systick_irqaction);
sdev->irq_requested = 1;
iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
systick.membase + SYSTICK_CONFIG);
return 0;
}
static int __init ralink_systick_init(struct device_node *np)
{
int ret;
systick.membase = of_iomap(np, 0);
if (!systick.membase)
return -ENXIO;
systick_irqaction.name = np->name;
systick.dev.name = np->name;
clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev);
systick.dev.max_delta_ticks = 0x7fff;
systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
systick.dev.min_delta_ticks = 0x3;
systick.dev.irq = irq_of_parse_and_map(np, 0);
if (!systick.dev.irq) {
pr_err("%s: request_irq failed", np->name);
return -EINVAL;
}
ret = clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
SYSTICK_FREQ, 301, 16,
clocksource_mmio_readl_up);
if (ret)
return ret;
clockevents_register_device(&systick.dev);
pr_info("%s: running - mult: %d, shift: %d\n",
np->name, systick.dev.mult, systick.dev.shift);
return 0;
}
TIMER_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);
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