[RFC PATCH 09/10] alpha: Switch to GENERIC_CLOCKEVENTS
From: Richard Henderson
Date: Tue Jul 16 2013 - 13:35:56 EST
This allows us to get rid of some hacky code for SMP. Get rid of
some cycle counter hackery that's now handled by generic code via
clocksource + clock_event_device objects.
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Richard Henderson <rth@xxxxxxxxxxx>
---
arch/alpha/Kconfig | 1 +
arch/alpha/kernel/irq_alpha.c | 14 ------
arch/alpha/kernel/proto.h | 2 +-
arch/alpha/kernel/smp.c | 33 ++-----------
arch/alpha/kernel/time.c | 111 ++++++++++++++++++------------------------
5 files changed, 52 insertions(+), 109 deletions(-)
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 7e268cf..5b57618 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -16,6 +16,7 @@ config ALPHA
select ARCH_WANT_IPC_PARSE_VERSION
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
+ select GENERIC_CLOCKEVENTS
select GENERIC_SMP_IDLE_THREAD
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
diff --git a/arch/alpha/kernel/irq_alpha.c b/arch/alpha/kernel/irq_alpha.c
index f433fc1..49d50e2 100644
--- a/arch/alpha/kernel/irq_alpha.c
+++ b/arch/alpha/kernel/irq_alpha.c
@@ -66,21 +66,7 @@ do_entInt(unsigned long type, unsigned long vector,
break;
case 1:
old_regs = set_irq_regs(regs);
-#ifdef CONFIG_SMP
- {
- long cpu;
-
- smp_percpu_timer_interrupt(regs);
- cpu = smp_processor_id();
- if (cpu != boot_cpuid) {
- kstat_incr_irqs_this_cpu(RTC_IRQ, irq_to_desc(RTC_IRQ));
- } else {
- handle_irq(RTC_IRQ);
- }
- }
-#else
handle_irq(RTC_IRQ);
-#endif
set_irq_regs(old_regs);
return;
case 2:
diff --git a/arch/alpha/kernel/proto.h b/arch/alpha/kernel/proto.h
index b0c8498..175f7a4 100644
--- a/arch/alpha/kernel/proto.h
+++ b/arch/alpha/kernel/proto.h
@@ -135,13 +135,13 @@ extern void unregister_srm_console(void);
/* smp.c */
extern void setup_smp(void);
extern void handle_ipi(struct pt_regs *);
-extern void smp_percpu_timer_interrupt(struct pt_regs *);
/* bios32.c */
/* extern void reset_for_srm(void); */
/* time.c */
extern irqreturn_t timer_interrupt(int irq, void *dev);
+extern void init_clockevent(void);
extern void common_init_rtc(void);
extern unsigned long est_cycle_freq;
diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 7b60834..1a8a10e 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -138,9 +138,11 @@ smp_callin(void)
/* Get our local ticker going. */
smp_setup_percpu_timer(cpuid);
+ init_clockevent();
/* Call platform-specific callin, if specified */
- if (alpha_mv.smp_callin) alpha_mv.smp_callin();
+ if (alpha_mv.smp_callin)
+ alpha_mv.smp_callin();
/* All kernel threads share the same mm context. */
atomic_inc(&init_mm.mm_count);
@@ -497,35 +499,6 @@ smp_cpus_done(unsigned int max_cpus)
((bogosum + 2500) / (5000/HZ)) % 100);
}
-
-void
-smp_percpu_timer_interrupt(struct pt_regs *regs)
-{
- struct pt_regs *old_regs;
- int cpu = smp_processor_id();
- unsigned long user = user_mode(regs);
- struct cpuinfo_alpha *data = &cpu_data[cpu];
-
- old_regs = set_irq_regs(regs);
-
- /* Record kernel PC. */
- profile_tick(CPU_PROFILING);
-
- if (!--data->prof_counter) {
- /* We need to make like a normal interrupt -- otherwise
- timer interrupts ignore the global interrupt lock,
- which would be a Bad Thing. */
- irq_enter();
-
- update_process_times(user);
-
- data->prof_counter = data->prof_multiplier;
-
- irq_exit();
- }
- set_irq_regs(old_regs);
-}
-
int
setup_profiling_timer(unsigned int multiplier)
{
diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c
index cadb82b..ec45001 100644
--- a/arch/alpha/kernel/time.c
+++ b/arch/alpha/kernel/time.c
@@ -42,6 +42,7 @@
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/clocksource.h>
+#include <linux/clockchips.h>
#include "proto.h"
#include "irq_impl.h"
@@ -49,25 +50,6 @@
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);
-#define TICK_SIZE (tick_nsec / 1000)
-
-/*
- * Shift amount by which scaled_ticks_per_cycle is scaled. Shifting
- * by 48 gives us 16 bits for HZ while keeping the accuracy good even
- * for large CPU clock rates.
- */
-#define FIX_SHIFT 48
-
-/* lump static variables together for more efficient access: */
-static struct {
- /* cycle counter last time it got invoked */
- __u32 last_time;
- /* ticks/cycle * 2^48 */
- unsigned long scaled_ticks_per_cycle;
- /* partial unused tick */
- unsigned long partial_tick;
-} state;
-
unsigned long est_cycle_freq;
#ifdef CONFIG_IRQ_WORK
@@ -98,49 +80,63 @@ static inline __u32 rpcc(void)
return result;
}
+
+
/*
- * timer_interrupt() needs to keep up the real-time clock,
- * as well as call the "xtime_update()" routine every clocktick
+ * The RTC as a clock_event_device primitive.
*/
-irqreturn_t timer_interrupt(int irq, void *dev)
-{
- unsigned long delta;
- __u32 now;
- long nticks;
-#ifndef CONFIG_SMP
- /* Not SMP, do kernel PC profiling here. */
- profile_tick(CPU_PROFILING);
-#endif
+static DEFINE_PER_CPU(struct clock_event_device, cpu_ce);
- /*
- * Calculate how many ticks have passed since the last update,
- * including any previous partial leftover. Save any resulting
- * fraction for the next pass.
- */
- now = rpcc();
- delta = now - state.last_time;
- state.last_time = now;
- delta = delta * state.scaled_ticks_per_cycle + state.partial_tick;
- state.partial_tick = delta & ((1UL << FIX_SHIFT) - 1);
- nticks = delta >> FIX_SHIFT;
+irqreturn_t
+timer_interrupt(int irq, void *dev)
+{
+ int cpu = smp_processor_id();
+ struct clock_event_device *ce = &per_cpu(cpu_ce, cpu);
- if (nticks)
- xtime_update(nticks);
+ /* Don't run the hook for UNUSED or SHUTDOWN. */
+ if (likely(ce->mode == CLOCK_EVT_MODE_PERIODIC))
+ ce->event_handler(ce);
if (test_irq_work_pending()) {
clear_irq_work_pending();
irq_work_run();
}
-#ifndef CONFIG_SMP
- while (nticks--)
- update_process_times(user_mode(get_irq_regs()));
-#endif
-
return IRQ_HANDLED;
}
+static void
+rtc_ce_set_mode(enum clock_event_mode mode, struct clock_event_device *ce)
+{
+ /* The mode member of CE is updated in generic code.
+ Since we only support periodic events, nothing to do. */
+}
+static int
+rtc_ce_set_next_event(unsigned long evt, struct clock_event_device *ce)
+{
+ /* This hook is for oneshot mode, which we don't support. */
+ return -EINVAL;
+}
+
+void __init
+init_clockevent(void)
+{
+ int cpu = smp_processor_id();
+ struct clock_event_device *ce = &per_cpu(cpu_ce, cpu);
+
+ *ce = (struct clock_event_device){
+ .name = "rtc",
+ .features = CLOCK_EVT_FEAT_PERIODIC,
+ .rating = 100,
+ .cpumask = cpumask_of(cpu),
+ .set_mode = rtc_ce_set_mode,
+ .set_next_event = rtc_ce_set_next_event,
+ };
+
+ clockevents_config_and_register(ce, CONFIG_HZ, 0, 0);
+}
+
void __init
common_init_rtc(void)
{
@@ -365,22 +361,9 @@ time_init(void)
if (hwrpb->nr_processors == 1)
clocksource_register_hz(&clocksource_rpcc, cycle_freq);
- /* From John Bowman <bowman@xxxxxxxxxxxxxxxx>: allow the values
- to settle, as the Update-In-Progress bit going low isn't good
- enough on some hardware. 2ms is our guess; we haven't found
- bogomips yet, but this is close on a 500Mhz box. */
- __delay(1000000);
-
- if (HZ > (1<<16)) {
- extern void __you_loose (void);
- __you_loose();
- }
-
- state.last_time = cc1;
- state.scaled_ticks_per_cycle
- = ((unsigned long) HZ << FIX_SHIFT) / cycle_freq;
- state.partial_tick = 0L;
-
/* Startup the timer source. */
alpha_mv.init_rtc();
+
+ /* Start up the clock event device. */
+ init_clockevent();
}
--
1.8.1.4
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