alpha: Switch to GENERIC_CLOCKEVENTS

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.

Signed-off-by: Richard Henderson <rth@twiddle.net>

5 files changed, 53 insertions, 109 deletions

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 5d863d171b94..d39dc9b95a2c 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 28e4429596f3..6990ddc0fbaf 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 3b250fa5f2c1..bc806893afe0 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 9dbbcb3b9146..99ac36d5de4e 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);
@@ -498,35 +500,6 @@ 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 0d72e2df4b0e..08ff3f502a76 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
@@ -96,49 +78,64 @@ static inline __u32 rpcc(void)
         return __builtin_alpha_rpcc();
 }
 
+
+
 /*
- * 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)
 {
@@ -372,22 +369,9 @@ time_init(void)
                 clocksource_register_hz(&clocksource_rpcc, cycle_freq);
 #endif
 
-        /* From John Bowman <bowman@math.ualberta.ca>: 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();
 }