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/*
* Copyright (c) 2014 Zhang, Keguang <keguang.zhang@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.
*/
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <asm/time.h>
#include <loongson1.h>
#include <platform.h>
#ifdef CONFIG_CEVT_CSRC_LS1X
#if defined(CONFIG_TIMER_USE_PWM1)
#define LS1X_TIMER_BASE LS1X_PWM1_BASE
#define LS1X_TIMER_IRQ LS1X_PWM1_IRQ
#elif defined(CONFIG_TIMER_USE_PWM2)
#define LS1X_TIMER_BASE LS1X_PWM2_BASE
#define LS1X_TIMER_IRQ LS1X_PWM2_IRQ
#elif defined(CONFIG_TIMER_USE_PWM3)
#define LS1X_TIMER_BASE LS1X_PWM3_BASE
#define LS1X_TIMER_IRQ LS1X_PWM3_IRQ
#else
#define LS1X_TIMER_BASE LS1X_PWM0_BASE
#define LS1X_TIMER_IRQ LS1X_PWM0_IRQ
#endif
DEFINE_RAW_SPINLOCK(ls1x_timer_lock);
static void __iomem *timer_base;
static uint32_t ls1x_jiffies_per_tick;
static inline void ls1x_pwmtimer_set_period(uint32_t period)
{
__raw_writel(period, timer_base + PWM_HRC);
__raw_writel(period, timer_base + PWM_LRC);
}
static inline void ls1x_pwmtimer_restart(void)
{
__raw_writel(0x0, timer_base + PWM_CNT);
__raw_writel(INT_EN | CNT_EN, timer_base + PWM_CTRL);
}
void __init ls1x_pwmtimer_init(void)
{
timer_base = ioremap(LS1X_TIMER_BASE, 0xf);
if (!timer_base)
panic("Failed to remap timer registers");
ls1x_jiffies_per_tick = DIV_ROUND_CLOSEST(mips_hpt_frequency, HZ);
ls1x_pwmtimer_set_period(ls1x_jiffies_per_tick);
ls1x_pwmtimer_restart();
}
static cycle_t ls1x_clocksource_read(struct clocksource *cs)
{
unsigned long flags;
int count;
u32 jifs;
static int old_count;
static u32 old_jifs;
raw_spin_lock_irqsave(&ls1x_timer_lock, flags);
/*
* Although our caller may have the read side of xtime_lock,
* this is now a seqlock, and we are cheating in this routine
* by having side effects on state that we cannot undo if
* there is a collision on the seqlock and our caller has to
* retry. (Namely, old_jifs and old_count.) So we must treat
* jiffies as volatile despite the lock. We read jiffies
* before latching the timer count to guarantee that although
* the jiffies value might be older than the count (that is,
* the counter may underflow between the last point where
* jiffies was incremented and the point where we latch the
* count), it cannot be newer.
*/
jifs = jiffies;
/* read the count */
count = __raw_readl(timer_base + PWM_CNT);
/*
* It's possible for count to appear to go the wrong way for this
* reason:
*
* The timer counter underflows, but we haven't handled the resulting
* interrupt and incremented jiffies yet.
*
* Previous attempts to handle these cases intelligently were buggy, so
* we just do the simple thing now.
*/
if (count < old_count && jifs == old_jifs)
count = old_count;
old_count = count;
old_jifs = jifs;
raw_spin_unlock_irqrestore(&ls1x_timer_lock, flags);
return (cycle_t) (jifs * ls1x_jiffies_per_tick) + count;
}
static struct clocksource ls1x_clocksource = {
.name = "ls1x-pwmtimer",
.read = ls1x_clocksource_read,
.mask = CLOCKSOURCE_MASK(24),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static irqreturn_t ls1x_clockevent_isr(int irq, void *devid)
{
struct clock_event_device *cd = devid;
ls1x_pwmtimer_restart();
cd->event_handler(cd);
return IRQ_HANDLED;
}
static int ls1x_clockevent_set_state_periodic(struct clock_event_device *cd)
{
raw_spin_lock(&ls1x_timer_lock);
ls1x_pwmtimer_set_period(ls1x_jiffies_per_tick);
ls1x_pwmtimer_restart();
__raw_writel(INT_EN | CNT_EN, timer_base + PWM_CTRL);
raw_spin_unlock(&ls1x_timer_lock);
return 0;
}
static int ls1x_clockevent_tick_resume(struct clock_event_device *cd)
{
raw_spin_lock(&ls1x_timer_lock);
__raw_writel(INT_EN | CNT_EN, timer_base + PWM_CTRL);
raw_spin_unlock(&ls1x_timer_lock);
return 0;
}
static int ls1x_clockevent_set_state_shutdown(struct clock_event_device *cd)
{
raw_spin_lock(&ls1x_timer_lock);
__raw_writel(__raw_readl(timer_base + PWM_CTRL) & ~CNT_EN,
timer_base + PWM_CTRL);
raw_spin_unlock(&ls1x_timer_lock);
return 0;
}
static int ls1x_clockevent_set_next(unsigned long evt,
struct clock_event_device *cd)
{
raw_spin_lock(&ls1x_timer_lock);
ls1x_pwmtimer_set_period(evt);
ls1x_pwmtimer_restart();
raw_spin_unlock(&ls1x_timer_lock);
return 0;
}
static struct clock_event_device ls1x_clockevent = {
.name = "ls1x-pwmtimer",
.features = CLOCK_EVT_FEAT_PERIODIC,
.rating = 300,
.irq = LS1X_TIMER_IRQ,
.set_next_event = ls1x_clockevent_set_next,
.set_state_shutdown = ls1x_clockevent_set_state_shutdown,
.set_state_periodic = ls1x_clockevent_set_state_periodic,
.set_state_oneshot = ls1x_clockevent_set_state_shutdown,
.tick_resume = ls1x_clockevent_tick_resume,
};
static struct irqaction ls1x_pwmtimer_irqaction = {
.name = "ls1x-pwmtimer",
.handler = ls1x_clockevent_isr,
.dev_id = &ls1x_clockevent,
.flags = IRQF_PERCPU | IRQF_TIMER,
};
static void __init ls1x_time_init(void)
{
struct clock_event_device *cd = &ls1x_clockevent;
int ret;
if (!mips_hpt_frequency)
panic("Invalid timer clock rate");
ls1x_pwmtimer_init();
clockevent_set_clock(cd, mips_hpt_frequency);
cd->max_delta_ns = clockevent_delta2ns(0xffffff, cd);
cd->min_delta_ns = clockevent_delta2ns(0x000300, cd);
cd->cpumask = cpumask_of(smp_processor_id());
clockevents_register_device(cd);
ls1x_clocksource.rating = 200 + mips_hpt_frequency / 10000000;
ret = clocksource_register_hz(&ls1x_clocksource, mips_hpt_frequency);
if (ret)
panic(KERN_ERR "Failed to register clocksource: %d\n", ret);
setup_irq(LS1X_TIMER_IRQ, &ls1x_pwmtimer_irqaction);
}
#endif /* CONFIG_CEVT_CSRC_LS1X */
void __init plat_time_init(void)
{
struct clk *clk = NULL;
/* initialize LS1X clocks */
ls1x_clk_init();
#ifdef CONFIG_CEVT_CSRC_LS1X
/* setup LS1X PWM timer */
clk = clk_get(NULL, "ls1x_pwmtimer");
if (IS_ERR(clk))
panic("unable to get timer clock, err=%ld", PTR_ERR(clk));
mips_hpt_frequency = clk_get_rate(clk);
ls1x_time_init();
#else
/* setup mips r4k timer */
clk = clk_get(NULL, "cpu_clk");
if (IS_ERR(clk))
panic("unable to get cpu clock, err=%ld", PTR_ERR(clk));
mips_hpt_frequency = clk_get_rate(clk) / 2;
#endif /* CONFIG_CEVT_CSRC_LS1X */
}
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