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iop: clocksource support 

This updates the IOP platform to expose the free-running
timer 1 as a clocksource object. This timer is now also
properly initialised, which requires a new write_tcr1()
function from the mach-specific code. Apart from the
explicit initialisation, there is no functional change
in how timer 1 is programmed.

Tested on n2100, compile-tested for all plat-iop machines.

Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Mikael Pettersson 2009-10-29 11:46:54 -07:00 committed by Dan Williams
parent 012abeea66
commit a91549a8f2
3 changed files with 55 additions and 0 deletions
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5
arch/arm/include/asm/hardware/iop3xx.h
View File

@ -260,6 +260,11 @@ static inline u32 read_tcr1(void)
return val;
}
static inline void write_tcr1(u32 val)
{
asm volatile("mcr p6, 0, %0, c3, c1, 0" : : "r" (val));
}
static inline void write_trr0(u32 val)
{
asm volatile("mcr p6, 0, %0, c4, c1, 0" : : "r" (val));

5
arch/arm/mach-iop13xx/include/mach/time.h
View File

@ -90,6 +90,11 @@ static inline u32 read_tcr1(void)
return val;
}
static inline void write_tcr1(u32 val)
{
asm volatile("mcr p6, 0, %0, c3, c9, 0" : : "r" (val));
}
static inline void write_trr0(u32 val)
{
asm volatile("mcr p6, 0, %0, c4, c9, 0" : : "r" (val));

45
arch/arm/plat-iop/time.c
View File

@ -19,6 +19,7 @@
#include <linux/init.h>
#include <linux/timex.h>
#include <linux/io.h>
#include <linux/clocksource.h>
#include <mach/hardware.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
@ -26,6 +27,43 @@
#include <asm/mach/time.h>
#include <mach/time.h>
/*
* IOP clocksource (free-running timer 1).
*/
static cycle_t iop_clocksource_read(struct clocksource *unused)
{
return 0xffffffffu - read_tcr1();
}
static struct clocksource iop_clocksource = {
.name = "iop_timer1",
.rating = 300,
.read = iop_clocksource_read,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static void __init iop_clocksource_set_hz(struct clocksource *cs, unsigned int hz)
{
u64 temp;
u32 shift;
/* Find shift and mult values for hz. */
shift = 32;
do {
temp = (u64) NSEC_PER_SEC << shift;
do_div(temp, hz);
if ((temp >> 32) == 0)
break;
} while (--shift != 0);
cs->shift = shift;
cs->mult = (u32) temp;
printk(KERN_INFO "clocksource: %s uses shift %u mult %#x\n",
cs->name, cs->shift, cs->mult);
}
static unsigned long ticks_per_jiffy;
static unsigned long ticks_per_usec;
static unsigned long next_jiffy_time;
@ -99,8 +137,15 @@ void __init iop_init_time(unsigned long tick_rate)
*/
write_trr0(ticks_per_jiffy - 1);
write_tmr0(timer_ctl);
/*
* Set up free-running clocksource timer 1.
*/
write_trr1(0xffffffff);
write_tcr1(0xffffffff);
write_tmr1(timer_ctl);
iop_clocksource_set_hz(&iop_clocksource, tick_rate);
clocksource_register(&iop_clocksource);
setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq);
}