Commit f2b8901d authored by Sascha Hauer's avatar Sascha Hauer Committed by Uwe Kleine-König
Browse files

ARM: imx: Add EPIT support



The Enhanced Periodic Interrupt Timer (EPIT) is found on newer
i.MX SoCs and can be used as an alternative system timer.
Signed-off-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: default avatarMichael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
parent ab3d8b58
......@@ -92,6 +92,18 @@ config MXC_DEBUG_BOARD
data/address de-multiplexing and decode, signal level shift,
interrupt control and various board functions.
config HAVE_EPIT
bool
config MXC_USE_EPIT
bool "Use EPIT instead of GPT"
depends on HAVE_EPIT
help
Use EPIT as the system timer on systems that have it. Normally you
don't have a reason to do so as the EPIT has the same features and
uses the same clocks as the GPT. Anyway, on some systems the GPT
may be in use for other purposes.
config MXC_ULPI
bool
......
......@@ -13,6 +13,7 @@ obj-$(CONFIG_ARCH_MXC_IOMUX_V3) += iomux-v3.o
obj-$(CONFIG_MXC_PWM) += pwm.o
obj-$(CONFIG_USB_EHCI_MXC) += ehci.o
obj-$(CONFIG_MXC_ULPI) += ulpi.o
obj-$(CONFIG_MXC_USE_EPIT) += epit.o
obj-$(CONFIG_ARCH_MXC_AUDMUX_V1) += audmux-v1.o
obj-$(CONFIG_ARCH_MXC_AUDMUX_V2) += audmux-v2.o
obj-$(CONFIG_MXC_DEBUG_BOARD) += 3ds_debugboard.o
......
/*
* 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 cycle_t epit_read(struct clocksource *cs)
{
return 0 - __raw_readl(timer_base + EPITCNR);
}
static struct clocksource clocksource_epit = {
.name = "epit",
.rating = 200,
.read = epit_read,
.mask = CLOCKSOURCE_MASK(32),
.shift = 20,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static int __init epit_clocksource_init(struct clk *timer_clk)
{
unsigned int c = clk_get_rate(timer_clk);
clocksource_epit.mult = clocksource_hz2mult(c,
clocksource_epit.shift);
clocksource_register(&clocksource_epit);
return 0;
}
/* 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);
}
......@@ -32,6 +32,7 @@ extern void mx31_init_irq(void);
extern void mx35_init_irq(void);
extern void mx51_init_irq(void);
extern void mxc91231_init_irq(void);
extern void epit_timer_init(struct clk *timer_clk, void __iomem *base, int irq);
extern void mxc_timer_init(struct clk *timer_clk, void __iomem *, int);
extern int mx1_clocks_init(unsigned long fref);
extern int mx21_clocks_init(unsigned long lref, unsigned long fref);
......
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