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/*
* linux/arch/arm/plat-mxc/epit.c
*
* Copyright (C) 2010 Sascha Hauer <s.hauer@pengutronix.de>
*
* 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., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#define EPITCR 0x00
#define EPITSR 0x04
#define EPITLR 0x08
#define EPITCMPR 0x0c
#define EPITCNR 0x10
#define EPITCR_EN (1 << 0)
#define EPITCR_ENMOD (1 << 1)
#define EPITCR_OCIEN (1 << 2)
#define EPITCR_RLD (1 << 3)
#define EPITCR_PRESC(x) (((x) & 0xfff) << 4)
#define EPITCR_SWR (1 << 16)
#define EPITCR_IOVW (1 << 17)
#define EPITCR_DBGEN (1 << 18)
#define EPITCR_WAITEN (1 << 19)
#define EPITCR_RES (1 << 20)
#define EPITCR_STOPEN (1 << 21)
#define EPITCR_OM_DISCON (0 << 22)
#define EPITCR_OM_TOGGLE (1 << 22)
#define EPITCR_OM_CLEAR (2 << 22)
#define EPITCR_OM_SET (3 << 22)
#define EPITCR_CLKSRC_OFF (0 << 24)
#define EPITCR_CLKSRC_PERIPHERAL (1 << 24)
#define EPITCR_CLKSRC_REF_HIGH (1 << 24)
#define EPITCR_CLKSRC_REF_LOW (3 << 24)
#define EPITSR_OCIF (1 << 0)
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/clockchips.h>
#include <linux/clk.h>
#include <mach/hardware.h>
#include <asm/mach/time.h>
#include <mach/common.h>
static struct clock_event_device clockevent_epit;
static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
static void __iomem *timer_base;
static inline void epit_irq_disable(void)
{
u32 val;
val = __raw_readl(timer_base + EPITCR);
val &= ~EPITCR_OCIEN;
__raw_writel(val, timer_base + EPITCR);
}
static inline void epit_irq_enable(void)
{
u32 val;
val = __raw_readl(timer_base + EPITCR);
val |= EPITCR_OCIEN;
__raw_writel(val, timer_base + EPITCR);
}
static void epit_irq_acknowledge(void)
{
__raw_writel(EPITSR_OCIF, timer_base + EPITSR);
}
static int __init epit_clocksource_init(struct clk *timer_clk)
{
unsigned int c = clk_get_rate(timer_clk);
return clocksource_mmio_init(timer_base + EPITCNR, "epit", c, 200, 32,
clocksource_mmio_readl_down);
}
/* clock event */
static int epit_set_next_event(unsigned long evt,
struct clock_event_device *unused)
{
unsigned long tcmp;
tcmp = __raw_readl(timer_base + EPITCNR);
__raw_writel(tcmp - evt, timer_base + EPITCMPR);
return 0;
}
static void epit_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
unsigned long flags;
/*
* The timer interrupt generation is disabled at least
* for enough time to call epit_set_next_event()
*/
local_irq_save(flags);
/* Disable interrupt in GPT module */
epit_irq_disable();
if (mode != clockevent_mode) {
/* Set event time into far-far future */
/* Clear pending interrupt */
epit_irq_acknowledge();
}
/* Remember timer mode */
clockevent_mode = mode;
local_irq_restore(flags);
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
printk(KERN_ERR "epit_set_mode: Periodic mode is not "
"supported for i.MX EPIT\n");
break;
case CLOCK_EVT_MODE_ONESHOT:
/*
* Do not put overhead of interrupt enable/disable into
* epit_set_next_event(), the core has about 4 minutes
* to call epit_set_next_event() or shutdown clock after
* mode switching
*/
local_irq_save(flags);
epit_irq_enable();
local_irq_restore(flags);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_RESUME:
/* Left event sources disabled, no more interrupts appear */
break;
}
}
/*
* IRQ handler for the timer
*/
static irqreturn_t epit_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &clockevent_epit;
epit_irq_acknowledge();
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction epit_timer_irq = {
.name = "i.MX EPIT Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = epit_timer_interrupt,
};
static struct clock_event_device clockevent_epit = {
.name = "epit",
.features = CLOCK_EVT_FEAT_ONESHOT,
.shift = 32,
.set_mode = epit_set_mode,
.set_next_event = epit_set_next_event,
.rating = 200,
};
static int __init epit_clockevent_init(struct clk *timer_clk)
{
unsigned int c = clk_get_rate(timer_clk);
clockevent_epit.mult = div_sc(c, NSEC_PER_SEC,
clockevent_epit.shift);
clockevent_epit.max_delta_ns =
clockevent_delta2ns(0xfffffffe, &clockevent_epit);
clockevent_epit.min_delta_ns =
clockevent_delta2ns(0x800, &clockevent_epit);
clockevent_epit.cpumask = cpumask_of(0);
clockevents_register_device(&clockevent_epit);
return 0;
}
void __init epit_timer_init(struct clk *timer_clk, void __iomem *base, int irq)
{
clk_enable(timer_clk);
timer_base = base;
/*
* Initialise to a known state (all timers off, and timing reset)
*/
__raw_writel(0x0, timer_base + EPITCR);
__raw_writel(0xffffffff, timer_base + EPITLR);
__raw_writel(EPITCR_EN | EPITCR_CLKSRC_REF_HIGH | EPITCR_WAITEN,
timer_base + EPITCR);
/* init and register the timer to the framework */
epit_clocksource_init(timer_clk);
epit_clockevent_init(timer_clk);
/* Make irqs happen */
setup_irq(irq, &epit_timer_irq);
}
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