/*
* Copyright (C) 2008 Manuel Lauss <mano@roarinelk.homelinux.net>
*
* Previous incarnations were:
* Copyright (C) 2001, 2006, 2008 MontaVista Software, <source@mvista.com>
* Copied and modified Carsten Langgaard's time.c
*
* Carsten Langgaard, carstenl@mips.com
* Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved.
*
* ########################################################################
*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope 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.,
* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
*
* ########################################################################
*
* Clocksource/event using the 32.768kHz-clocked Counter1 ('RTC' in the
* databooks). Firmware/Board init code must enable the counters in the
* counter control register, otherwise the CP0 counter clocksource/event
* will be installed instead (and use of 'wait' instruction is prohibited).
*/
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <asm/processor.h>
#include <asm/time.h>
#include <asm/mach-au1x00/au1000.h>
/* 32kHz clock enabled and detected */
#define CNTR_OK (SYS_CNTRL_E0 | SYS_CNTRL_32S)
static cycle_t au1x_counter1_read(struct clocksource *cs)
{
return au_readl(SYS_RTCREAD);
}
static struct clocksource au1x_counter1_clocksource = {
.name = "alchemy-counter1",
.read = au1x_counter1_read,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.rating = 100,
};
static int au1x_rtcmatch2_set_next_event(unsigned long delta,
struct clock_event_device *cd)
{
delta += au_readl(SYS_RTCREAD);
/* wait for register access */
while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_M21)
;
au_writel(delta, SYS_RTCMATCH2);
au_sync();
return 0;
}
static void au1x_rtcmatch2_set_mode(enum clock_event_mode mode,
struct clock_event_device *cd)
{
}
static irqreturn_t au1x_rtcmatch2_irq(int irq, void *dev_id)
{
struct clock_event_device *cd = dev_id;
cd->event_handler(cd);
return IRQ_HANDLED;
}
static struct clock_event_device au1x_rtcmatch2_clockdev = {
.name = "rtcmatch2",
.features = CLOCK_EVT_FEAT_ONESHOT,
.rating = 100,
.irq = AU1000_RTC_MATCH2_INT,
.set_next_event = au1x_rtcmatch2_set_next_event,
.set_mode = au1x_rtcmatch2_set_mode,
.cpumask = cpu_all_mask,
};
static struct irqaction au1x_rtcmatch2_irqaction = {
.handler = au1x_rtcmatch2_irq,
.flags = IRQF_DISABLED | IRQF_TIMER,
.name = "timer",
.dev_id = &au1x_rtcmatch2_clockdev,
};
void __init plat_time_init(void)
{
struct clock_event_device *cd = &au1x_rtcmatch2_clockdev;
unsigned long t;
/* Check if firmware (YAMON, ...) has enabled 32kHz and clock
* has been detected. If so install the rtcmatch2 clocksource,
* otherwise don't bother. Note that both bits being set is by
* no means a definite guarantee that the counters actually work
* (the 32S bit seems to be stuck set to 1 once a single clock-
* edge is detected, hence the timeouts).
*/
if (CNTR_OK != (au_readl(SYS_COUNTER_CNTRL) & CNTR_OK))
goto cntr_err;
/*
* setup counter 1 (RTC) to tick at full speed
*/
t = 0xffffff;
while ((au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T1S) && --t)
asm volatile ("nop");
if (!t)
goto cntr_err;
au_writel(0, SYS_RTCTRIM); /* 32.768 kHz */
au_sync();
t = 0xffffff;
while ((au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S) && --t)
asm volatile ("nop");
if (!t)
goto cntr_err;
au_writel(0, SYS_RTCWRITE);
au_sync();
t = 0xffffff;
while ((au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S) && --t)
asm volatile ("nop");
if (!t)
goto cntr_err;
/* register counter1 clocksource and event device */
clocksource_set_clock(&au1x_counter1_clocksource, 32768);
clocksource_register(&au1x_counter1_clocksource);
cd->shift = 32;
cd->mult = div_sc(32768, NSEC_PER_SEC, cd->shift);
cd->max_delta_ns = clockevent_delta2ns(0xffffffff, cd);
cd->min_delta_ns = clockevent_delta2ns(8, cd); /* ~0.25ms */
clockevents_register_device(cd);
setup_irq(AU1000_RTC_MATCH2_INT, &au1x_rtcmatch2_irqaction);
printk(KERN_INFO "Alchemy clocksource installed\n");
return;
cntr_err:
/*
* MIPS kernel assigns 'au1k_wait' to 'cpu_wait' before this
* function is called. Because the Alchemy counters are unusable
* the C0 timekeeping code is installed and use of the 'wait'
* instruction must be prohibited, which is done most easily by
* assigning NULL to cpu_wait.
*/
cpu_wait = NULL;
r4k_clockevent_init();
init_r4k_clocksource();
}
