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acrn-kernel/arch/arm/plat-omap/timer32k.c

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/*
* linux/arch/arm/plat-omap/timer32k.c
*
* OMAP 32K Timer
*
* Copyright (C) 2004 - 2005 Nokia Corporation
* Partial timer rewrite and additional dynamic tick timer support by
* Tony Lindgen <tony@atomide.com> and
* Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
* OMAP Dual-mode timer framework support by Timo Teras
*
* MPU timer code based on the older MPU timer code for OMAP
* Copyright (C) 2000 RidgeRun, Inc.
* Author: Greg Lonnon <glonnon@ridgerun.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.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
* NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* 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.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <asm/system.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/leds.h>
#include <asm/irq.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
#include <asm/arch/dmtimer.h>
struct sys_timer omap_timer;
/*
* ---------------------------------------------------------------------------
* 32KHz OS timer
*
* This currently works only on 16xx, as 1510 does not have the continuous
* 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
* of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
* on 1510 would be possible, but the timer would not be as accurate as
* with the 32KHz synchronized timer.
* ---------------------------------------------------------------------------
*/
#if defined(CONFIG_ARCH_OMAP16XX)
#define TIMER_32K_SYNCHRONIZED 0xfffbc410
#elif defined(CONFIG_ARCH_OMAP24XX)
#define TIMER_32K_SYNCHRONIZED 0x48004010
#else
#error OMAP 32KHz timer does not currently work on 15XX!
#endif
/* 16xx specific defines */
#define OMAP1_32K_TIMER_BASE 0xfffb9000
#define OMAP1_32K_TIMER_CR 0x08
#define OMAP1_32K_TIMER_TVR 0x00
#define OMAP1_32K_TIMER_TCR 0x04
#define OMAP_32K_TICKS_PER_HZ (32768 / HZ)
/*
* TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
* so with HZ = 128, TVR = 255.
*/
#define OMAP_32K_TIMER_TICK_PERIOD ((32768 / HZ) - 1)
#define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate) \
(((nr_jiffies) * (clock_rate)) / HZ)
#if defined(CONFIG_ARCH_OMAP1)
static inline void omap_32k_timer_write(int val, int reg)
{
omap_writew(val, OMAP1_32K_TIMER_BASE + reg);
}
static inline unsigned long omap_32k_timer_read(int reg)
{
return omap_readl(OMAP1_32K_TIMER_BASE + reg) & 0xffffff;
}
static inline void omap_32k_timer_start(unsigned long load_val)
{
if (!load_val)
load_val = 1;
omap_32k_timer_write(load_val, OMAP1_32K_TIMER_TVR);
omap_32k_timer_write(0x0f, OMAP1_32K_TIMER_CR);
}
static inline void omap_32k_timer_stop(void)
{
omap_32k_timer_write(0x0, OMAP1_32K_TIMER_CR);
}
#define omap_32k_timer_ack_irq()
#elif defined(CONFIG_ARCH_OMAP2)
static struct omap_dm_timer *gptimer;
static inline void omap_32k_timer_start(unsigned long load_val)
{
omap_dm_timer_set_load(gptimer, 1, 0xffffffff - load_val);
omap_dm_timer_set_int_enable(gptimer, OMAP_TIMER_INT_OVERFLOW);
omap_dm_timer_start(gptimer);
}
static inline void omap_32k_timer_stop(void)
{
omap_dm_timer_stop(gptimer);
}
static inline void omap_32k_timer_ack_irq(void)
{
u32 status = omap_dm_timer_read_status(gptimer);
omap_dm_timer_write_status(gptimer, status);
}
#endif
/*
* The 32KHz synchronized timer is an additional timer on 16xx.
* It is always running.
*/
static inline unsigned long omap_32k_sync_timer_read(void)
{
return omap_readl(TIMER_32K_SYNCHRONIZED);
}
/*
* Rounds down to nearest usec. Note that this will overflow for larger values.
*/
static inline unsigned long omap_32k_ticks_to_usecs(unsigned long ticks_32k)
{
return (ticks_32k * 5*5*5*5*5*5) >> 9;
}
/*
* Rounds down to nearest nsec.
*/
static inline unsigned long long
omap_32k_ticks_to_nsecs(unsigned long ticks_32k)
{
return (unsigned long long) ticks_32k * 1000 * 5*5*5*5*5*5 >> 9;
}
static unsigned long omap_32k_last_tick = 0;
/*
* Returns elapsed usecs since last 32k timer interrupt
*/
static unsigned long omap_32k_timer_gettimeoffset(void)
{
unsigned long now = omap_32k_sync_timer_read();
return omap_32k_ticks_to_usecs(now - omap_32k_last_tick);
}
/*
* Returns current time from boot in nsecs. It's OK for this to wrap
* around for now, as it's just a relative time stamp.
*/
unsigned long long sched_clock(void)
{
return omap_32k_ticks_to_nsecs(omap_32k_sync_timer_read());
}
/*
* Timer interrupt for 32KHz timer. When dynamic tick is enabled, this
* function is also called from other interrupts to remove latency
* issues with dynamic tick. In the dynamic tick case, we need to lock
* with irqsave.
*/
static inline irqreturn_t _omap_32k_timer_interrupt(int irq, void *dev_id)
{
unsigned long now;
omap_32k_timer_ack_irq();
now = omap_32k_sync_timer_read();
while ((signed long)(now - omap_32k_last_tick)
>= OMAP_32K_TICKS_PER_HZ) {
omap_32k_last_tick += OMAP_32K_TICKS_PER_HZ;
timer_tick();
}
/* Restart timer so we don't drift off due to modulo or dynamic tick.
* By default we program the next timer to be continuous to avoid
* latencies during high system load. During dynamic tick operation the
* continuous timer can be overridden from pm_idle to be longer.
*/
omap_32k_timer_start(omap_32k_last_tick + OMAP_32K_TICKS_PER_HZ - now);
return IRQ_HANDLED;
}
static irqreturn_t omap_32k_timer_handler(int irq, void *dev_id)
{
return _omap_32k_timer_interrupt(irq, dev_id);
}
static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
{
unsigned long flags;
write_seqlock_irqsave(&xtime_lock, flags);
_omap_32k_timer_interrupt(irq, dev_id);
write_sequnlock_irqrestore(&xtime_lock, flags);
return IRQ_HANDLED;
}
#ifdef CONFIG_NO_IDLE_HZ
/*
* Programs the next timer interrupt needed. Called when dynamic tick is
* enabled, and to reprogram the ticks to skip from pm_idle. Note that
* we can keep the timer continuous, and don't need to set it to run in
* one-shot mode. This is because the timer will get reprogrammed again
* after next interrupt.
*/
void omap_32k_timer_reprogram(unsigned long next_tick)
{
unsigned long ticks = JIFFIES_TO_HW_TICKS(next_tick, 32768) + 1;
unsigned long now = omap_32k_sync_timer_read();
unsigned long idled = now - omap_32k_last_tick;
if (idled + 1 < ticks)
ticks -= idled;
else
ticks = 1;
omap_32k_timer_start(ticks);
}
static struct irqaction omap_32k_timer_irq;
extern struct timer_update_handler timer_update;
static int omap_32k_timer_enable_dyn_tick(void)
{
/* No need to reprogram timer, just use the next interrupt */
return 0;
}
static int omap_32k_timer_disable_dyn_tick(void)
{
omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
return 0;
}
static struct dyn_tick_timer omap_dyn_tick_timer = {
.enable = omap_32k_timer_enable_dyn_tick,
.disable = omap_32k_timer_disable_dyn_tick,
.reprogram = omap_32k_timer_reprogram,
.handler = omap_32k_timer_handler,
};
#endif /* CONFIG_NO_IDLE_HZ */
static struct irqaction omap_32k_timer_irq = {
.name = "32KHz timer",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = omap_32k_timer_interrupt,
};
static __init void omap_init_32k_timer(void)
{
#ifdef CONFIG_NO_IDLE_HZ
omap_timer.dyn_tick = &omap_dyn_tick_timer;
#endif
if (cpu_class_is_omap1())
setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);
omap_timer.offset = omap_32k_timer_gettimeoffset;
omap_32k_last_tick = omap_32k_sync_timer_read();
#ifdef CONFIG_ARCH_OMAP2
/* REVISIT: Check 24xx TIOCP_CFG settings after idle works */
if (cpu_is_omap24xx()) {
gptimer = omap_dm_timer_request_specific(1);
BUG_ON(gptimer == NULL);
omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_32_KHZ);
setup_irq(omap_dm_timer_get_irq(gptimer), &omap_32k_timer_irq);
omap_dm_timer_set_int_enable(gptimer,
OMAP_TIMER_INT_CAPTURE | OMAP_TIMER_INT_OVERFLOW |
OMAP_TIMER_INT_MATCH);
}
#endif
omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
}
/*
* ---------------------------------------------------------------------------
* Timer initialization
* ---------------------------------------------------------------------------
*/
static void __init omap_timer_init(void)
{
#ifdef CONFIG_OMAP_DM_TIMER
omap_dm_timer_init();
#endif
omap_init_32k_timer();
}
struct sys_timer omap_timer = {
.init = omap_timer_init,
.offset = NULL, /* Initialized later */
};
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