/*
* linux/arch/arm/mach-nomadik/timer.c
*
* Copyright (C) 2008 STMicroelectronics
* Copyright (C) 2009 Alessandro Rubini, somewhat based on at91sam926x
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2, as
* published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/clockchips.h>
#include <linux/jiffies.h>
#include <asm/mach/time.h>
#include <mach/mtu.h>
#define TIMER_CTRL 0x80 /* No divisor */
#define TIMER_PERIODIC 0x40
#define TIMER_SZ32BIT 0x02
/* Initial value for SRC control register: all timers use MXTAL/8 source */
#define SRC_CR_INIT_MASK 0x00007fff
#define SRC_CR_INIT_VAL 0x2aaa8000
static u32 nmdk_count; /* accumulated count */
static u32 nmdk_cycle; /* write-once */
static __iomem void *mtu_base;
/*
* clocksource: the MTU device is a decrementing counters, so we negate
* the value being read.
*/
static cycle_t nmdk_read_timer(struct clocksource *cs)
{
u32 count = readl(mtu_base + MTU_VAL(0));
return nmdk_count + nmdk_cycle - count;
}
static struct clocksource nmdk_clksrc = {
.name = "mtu_0",
.rating = 120,
.read = nmdk_read_timer,
.shift = 20,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/*
* Clockevent device: currently only periodic mode is supported
*/
static void nmdk_clkevt_mode(enum clock_event_mode mode,
struct clock_event_device *dev)
{
unsigned long flags;
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
/* enable interrupts -- and count current value? */
raw_local_irq_save(flags);
writel(readl(mtu_base + MTU_IMSC) | 1, mtu_base + MTU_IMSC);
raw_local_irq_restore(flags);
break;
case CLOCK_EVT_MODE_ONESHOT:
BUG(); /* Not supported, yet */
/* FALLTHROUGH */
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
/* disable irq */
raw_local_irq_save(flags);
writel(readl(mtu_base + MTU_IMSC) & ~1, mtu_base + MTU_IMSC);
raw_local_irq_restore(flags);
break;
case CLOCK_EVT_MODE_RESUME:
break;
}
}
static struct clock_event_device nmdk_clkevt = {
.name = "mtu_0",
.features = CLOCK_EVT_FEAT_PERIODIC,
.shift = 32,
.rating = 100,
.set_mode = nmdk_clkevt_mode,
};
/*
* IRQ Handler for the timer 0 of the MTU block. The irq is not shared
* as we are the only users of mtu0 by now.
*/
static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id)
{
/* ack: "interrupt clear register" */
writel( 1 << 0, mtu_base + MTU_ICR);
/* we can't count lost ticks, unfortunately */
nmdk_count += nmdk_cycle;
nmdk_clkevt.event_handler(&nmdk_clkevt);
return IRQ_HANDLED;
}
/*
* Set up timer interrupt, and return the current time in seconds.
*/
static struct irqaction nmdk_timer_irq = {
.name = "Nomadik Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = nmdk_timer_interrupt,
};
static void nmdk_timer_reset(void)
{
u32 cr;
writel(0, mtu_base + MTU_CR(0)); /* off */
/* configure load and background-load, and fire it up */
writel(nmdk_cycle, mtu_base + MTU_LR(0));
writel(nmdk_cycle, mtu_base + MTU_BGLR(0));
cr = MTU_CRn_PERIODIC | MTU_CRn_PRESCALE_1 | MTU_CRn_32BITS;
writel(cr, mtu_base + MTU_CR(0));
writel(cr | MTU_CRn_ENA, mtu_base + MTU_CR(0));
}
static void __init nmdk_timer_init(void)
{
u32 src_cr;
unsigned long rate;
int bits;
rate = CLOCK_TICK_RATE; /* 2.4MHz */
nmdk_cycle = (rate + HZ/2) / HZ;
/* Configure timer sources in "system reset controller" ctrl reg */
src_cr = readl(io_p2v(NOMADIK_SRC_BASE));
src_cr &= SRC_CR_INIT_MASK;
src_cr |= SRC_CR_INIT_VAL;
writel(src_cr, io_p2v(NOMADIK_SRC_BASE));
/* Save global pointer to mtu, used by functions above */
mtu_base = io_p2v(NOMADIK_MTU0_BASE);
/* Init the timer and register clocksource */
nmdk_timer_reset();
nmdk_clksrc.mult = clocksource_hz2mult(rate, nmdk_clksrc.shift);
bits = 8*sizeof(nmdk_count);
nmdk_clksrc.mask = CLOCKSOURCE_MASK(bits);
clocksource_register(&nmdk_clksrc);
/* Register irq and clockevents */
setup_irq(IRQ_MTU0, &nmdk_timer_irq);
nmdk_clkevt.mult = div_sc(rate, NSEC_PER_SEC, nmdk_clkevt.shift);
nmdk_clkevt.cpumask = cpumask_of(0);
clockevents_register_device(&nmdk_clkevt);
}
struct sys_timer nomadik_timer = {
.init = nmdk_timer_init,
};
