[PATCH v2 2/4] iop: clockevent support
Mikael Pettersson
mikpe at it.uu.se
Sat Sep 26 15:50:54 EDT 2009
This updates the IOP platform to expose the interrupting
timer 0 as a clockevent object. The timer interrupt handler
is changed to call the clockevent ->event_handler() instead
of timer_tick(), and ->set_next_event() and ->set_mode()
operations are added to allow the mode of the timer to be
updated (required for ONESHOT/NOHZ mode).
Timer 0 must now be properly initialised, which requires
a new write_tcr0() function from the mach-specific code.
The mode of timer 0 must be read at the start of ->set_mode(),
which requires a new read_tmr0() function from the mach-
specific code.
Initial setup of timer 0 is also rewritten to be more robust.
Tested on n2100, compile-tested for all plat-iop machines.
Signed-off-by: Mikael Pettersson <mikpe at it.uu.se>
---
Changes v1 -> v2:
* rebased on 2.6.31 and v2 of the iop clocksource patch
* replaced static guess for the clockevent .shift value
with code to compute it at runtime, based on similar
code used in the mips kernel
* instead of computing &iop_clockevent in iop_timer_interrupt(),
use the iop_timer_irq.dev_id field to pass &iop_clockevent to
iop_timer_interrupt() via its dev_id parameter
* add read_tmr0() function to the mach-specific code, use it
to make iop_set_mode() do a read-modify-write of TMR0 for
every state change instead of making assumptions about TMR0
* minor cleanup in iop_set_next_event()
arch/arm/Kconfig | 1
arch/arm/include/asm/hardware/iop3xx.h | 12 +++
arch/arm/mach-iop13xx/include/mach/time.h | 12 +++
arch/arm/plat-iop/time.c | 101 ++++++++++++++++++++++++++----
4 files changed, 115 insertions(+), 11 deletions(-)
diff -rupN linux-2.6.31.arm-iop-1-clocksource-v2/arch/arm/Kconfig linux-2.6.31.arm-iop-2-clockevents-v2/arch/arm/Kconfig
--- linux-2.6.31.arm-iop-1-clocksource-v2/arch/arm/Kconfig 2009-09-10 13:41:49.000000000 +0200
+++ linux-2.6.31.arm-iop-2-clockevents-v2/arch/arm/Kconfig 2009-09-21 10:27:20.000000000 +0200
@@ -736,6 +736,7 @@ config ARCH_ACORN
config PLAT_IOP
bool
+ select GENERIC_CLOCKEVENTS
config PLAT_ORION
bool
diff -rupN linux-2.6.31.arm-iop-1-clocksource-v2/arch/arm/include/asm/hardware/iop3xx.h linux-2.6.31.arm-iop-2-clockevents-v2/arch/arm/include/asm/hardware/iop3xx.h
--- linux-2.6.31.arm-iop-1-clocksource-v2/arch/arm/include/asm/hardware/iop3xx.h 2009-09-21 10:26:06.000000000 +0200
+++ linux-2.6.31.arm-iop-2-clockevents-v2/arch/arm/include/asm/hardware/iop3xx.h 2009-09-21 10:27:20.000000000 +0200
@@ -235,6 +235,13 @@ void iop_init_cp6_handler(void);
void iop_init_time(unsigned long tickrate);
unsigned long iop_gettimeoffset(void);
+static inline u32 read_tmr0(void)
+{
+ u32 val;
+ asm volatile("mrc p6, 0, %0, c0, c1, 0" : "=r" (val));
+ return val;
+}
+
static inline void write_tmr0(u32 val)
{
asm volatile("mcr p6, 0, %0, c0, c1, 0" : : "r" (val));
@@ -252,6 +259,11 @@ static inline u32 read_tcr0(void)
return val;
}
+static inline void write_tcr0(u32 val)
+{
+ asm volatile("mcr p6, 0, %0, c2, c1, 0" : : "r" (val));
+}
+
static inline u32 read_tcr1(void)
{
u32 val;
diff -rupN linux-2.6.31.arm-iop-1-clocksource-v2/arch/arm/mach-iop13xx/include/mach/time.h linux-2.6.31.arm-iop-2-clockevents-v2/arch/arm/mach-iop13xx/include/mach/time.h
--- linux-2.6.31.arm-iop-1-clocksource-v2/arch/arm/mach-iop13xx/include/mach/time.h 2009-09-21 10:26:06.000000000 +0200
+++ linux-2.6.31.arm-iop-2-clockevents-v2/arch/arm/mach-iop13xx/include/mach/time.h 2009-09-21 10:27:20.000000000 +0200
@@ -66,6 +66,13 @@ static inline unsigned long iop13xx_xsi_
return 2;
}
+static inline u32 read_tmr0(void)
+{
+ u32 val;
+ asm volatile("mrc p6, 0, %0, c0, c9, 0" : "=r" (val));
+ return val;
+}
+
static inline void write_tmr0(u32 val)
{
asm volatile("mcr p6, 0, %0, c0, c9, 0" : : "r" (val));
@@ -83,6 +90,11 @@ static inline u32 read_tcr0(void)
return val;
}
+static inline void write_tcr0(u32 val)
+{
+ asm volatile("mcr p6, 0, %0, c2, c9, 0" : : "r" (val));
+}
+
static inline u32 read_tcr1(void)
{
u32 val;
diff -rupN linux-2.6.31.arm-iop-1-clocksource-v2/arch/arm/plat-iop/time.c linux-2.6.31.arm-iop-2-clockevents-v2/arch/arm/plat-iop/time.c
--- linux-2.6.31.arm-iop-1-clocksource-v2/arch/arm/plat-iop/time.c 2009-09-21 10:26:06.000000000 +0200
+++ linux-2.6.31.arm-iop-2-clockevents-v2/arch/arm/plat-iop/time.c 2009-09-21 10:27:20.000000000 +0200
@@ -20,6 +20,7 @@
#include <linux/timex.h>
#include <linux/io.h>
#include <linux/clocksource.h>
+#include <linux/clockchips.h>
#include <mach/hardware.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
@@ -64,7 +65,81 @@ static void __init iop_clocksource_set_h
cs->name, cs->shift, cs->mult);
}
+/*
+ * IOP clockevents (interrupting timer 0).
+ */
+static int iop_set_next_event(unsigned long delta,
+ struct clock_event_device *unused)
+{
+ u32 tmr = IOP_TMR_PRIVILEGED | IOP_TMR_RATIO_1_1;
+
+ BUG_ON(delta == 0);
+ write_tmr0(tmr & ~(IOP_TMR_EN | IOP_TMR_RELOAD));
+ write_tcr0(delta);
+ write_tmr0((tmr & ~IOP_TMR_RELOAD) | IOP_TMR_EN);
+
+ return 0;
+}
+
static unsigned long ticks_per_jiffy;
+
+static void iop_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *unused)
+{
+ u32 tmr = read_tmr0();
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ write_tmr0(tmr & ~IOP_TMR_EN);
+ write_tcr0(ticks_per_jiffy - 1);
+ tmr |= (IOP_TMR_RELOAD | IOP_TMR_EN);
+ break;
+ case CLOCK_EVT_MODE_ONESHOT:
+ /* ->set_next_event sets period and enables timer */
+ tmr &= ~(IOP_TMR_RELOAD | IOP_TMR_EN);
+ break;
+ case CLOCK_EVT_MODE_RESUME:
+ tmr |= IOP_TMR_EN;
+ break;
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ case CLOCK_EVT_MODE_UNUSED:
+ default:
+ tmr &= ~IOP_TMR_EN;
+ break;
+ }
+
+ write_tmr0(tmr);
+}
+
+static struct clock_event_device iop_clockevent = {
+ .name = "iop_timer0",
+ .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+ .rating = 300,
+ .set_next_event = iop_set_next_event,
+ .set_mode = iop_set_mode,
+};
+
+static void __init iop_clockevent_set_hz(struct clock_event_device *ce, unsigned int hz)
+{
+ u64 temp;
+ u32 shift;
+
+ /* Find shift and mult values for hz. */
+ shift = 32;
+ do {
+ temp = (u64) hz << shift;
+ do_div(temp, NSEC_PER_SEC);
+ if ((temp >> 32) == 0)
+ break;
+ } while (--shift != 0);
+
+ ce->shift = shift;
+ ce->mult = (u32) temp;
+
+ printk(KERN_INFO "clockevent: %s uses shift %u mult %#lx\n",
+ ce->name, ce->shift, ce->mult);
+}
+
static unsigned long ticks_per_usec;
static unsigned long next_jiffy_time;
@@ -95,14 +170,10 @@ unsigned long iop_gettimeoffset(void)
static irqreturn_t
iop_timer_interrupt(int irq, void *dev_id)
{
- write_tisr(1);
-
- while ((signed long)(next_jiffy_time - read_tcr1())
- >= ticks_per_jiffy) {
- timer_tick();
- next_jiffy_time -= ticks_per_jiffy;
- }
+ struct clock_event_device *evt = dev_id;
+ write_tisr(1);
+ evt->event_handler(evt);
return IRQ_HANDLED;
}
@@ -110,6 +181,7 @@ static struct irqaction iop_timer_irq =
.name = "IOP Timer Tick",
.handler = iop_timer_interrupt,
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+ .dev_id = &iop_clockevent,
};
static unsigned long iop_tick_rate;
@@ -132,10 +204,19 @@ void __init iop_init_time(unsigned long
IOP_TMR_RELOAD | IOP_TMR_RATIO_1_1;
/*
- * We use timer 0 for our timer interrupt, and timer 1 as
- * monotonic counter for tracking missed jiffies.
+ * Set up interrupting clockevent timer 0.
*/
+ write_tmr0(timer_ctl & ~IOP_TMR_EN);
+ setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq);
+ iop_clockevent_set_hz(&iop_clockevent, tick_rate);
+ iop_clockevent.max_delta_ns =
+ clockevent_delta2ns(0xfffffffe, &iop_clockevent);
+ iop_clockevent.min_delta_ns =
+ clockevent_delta2ns(0xf, &iop_clockevent);
+ iop_clockevent.cpumask = cpumask_of(0);
+ clockevents_register_device(&iop_clockevent);
write_trr0(ticks_per_jiffy - 1);
+ write_tcr0(ticks_per_jiffy - 1);
write_tmr0(timer_ctl);
/*
@@ -146,6 +227,4 @@ void __init iop_init_time(unsigned long
write_tmr1(timer_ctl);
iop_clocksource_set_hz(&iop_clocksource, tick_rate);
clocksource_register(&iop_clocksource);
-
- setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq);
}
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