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/*
* Moschip MCS814x timer routines
*
* Copyright (C) 2012, Florian Fainelli <florian@openwrt.org>
*
* Licensed under GPLv2
*/
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/irq.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <asm/mach/time.h>
#include <mach/mcs814x.h>
/* Timer block registers */
#define TIMER_VAL 0x00
#define TIMER_CTL 0x04
#define TIMER_CTL_EN 0x01
#define TIMER_CTL_DBG 0x02
static u32 last_reload;
static u32 timer_correct;
static u32 clock_rate;
static u32 timer_reload_value;
static void __iomem *mcs814x_timer_base;
static inline unsigned long ticks2usecs(u32 x)
{
return x / (clock_rate / 1000000);
}
/*
* Returns number of ms since last clock interrupt. Note that interrupts
* will have been disabled by do_gettimeoffset()
*/
static unsigned long mcs814x_gettimeoffset(void)
{
u32 ticks = readl_relaxed(mcs814x_timer_base + TIMER_VAL);
if (ticks < last_reload)
return ticks2usecs(ticks + (u32)(0xffffffff - last_reload));
else
return ticks2usecs(ticks - last_reload);
}
static irqreturn_t mcs814x_timer_interrupt(int irq, void *dev_id)
{
u32 count = readl_relaxed(mcs814x_timer_base + TIMER_VAL);
/* take into account delay up to this moment */
last_reload = count + timer_correct + timer_reload_value;
if (last_reload < timer_reload_value) {
last_reload = timer_reload_value;
} else {
if (timer_correct == 0)
timer_correct = readl_relaxed(mcs814x_timer_base + TIMER_VAL) - count;
}
writel_relaxed(last_reload, mcs814x_timer_base + TIMER_VAL);
timer_tick();
return IRQ_HANDLED;
}
static struct irqaction mcs814x_timer_irq = {
.name = "mcs814x-timer",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = mcs814x_timer_interrupt,
};
static struct of_device_id mcs814x_timer_ids[] = {
{ .compatible = "moschip,mcs814x-timer" },
{ /* sentinel */ },
};
static void __init mcs814x_of_timer_init(void)
{
struct device_node *np;
const unsigned int *intspec;
np = of_find_matching_node(NULL, mcs814x_timer_ids);
if (!np)
panic("unable to find compatible timer node in dtb");
mcs814x_timer_base = of_iomap(np, 0);
if (!mcs814x_timer_base)
panic("unable to remap timer cpu registers");
intspec = of_get_property(np, "interrupts", NULL);
if (!intspec)
panic("no interrupts property for timer");
mcs814x_timer_irq.irq = be32_to_cpup(intspec);
}
static void __init mcs814x_timer_init(void)
{
struct clk *clk;
clk = clk_get_sys("timer0", NULL);
if (IS_ERR_OR_NULL(clk))
panic("unable to get timer0 clock");
clock_rate = clk_get_rate(clk);
clk_put(clk);
mcs814x_of_timer_init();
pr_info("Timer frequency: %d (kHz)\n", clock_rate / 1000);
timer_reload_value = 0xffffffff - (clock_rate / HZ);
/* disable timer */
writel_relaxed(~TIMER_CTL_EN, mcs814x_timer_base + TIMER_CTL);
writel_relaxed(timer_reload_value, mcs814x_timer_base + TIMER_VAL);
last_reload = timer_reload_value;
setup_irq(mcs814x_timer_irq.irq, &mcs814x_timer_irq);
/* enable timer, stop timer in debug mode */
writel_relaxed(TIMER_CTL_EN | TIMER_CTL_DBG,
mcs814x_timer_base + TIMER_CTL);
}
struct sys_timer mcs814x_timer = {
.init = mcs814x_timer_init,
.offset = mcs814x_gettimeoffset,
};
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