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-rw-r--r--arch/openrisc/include/asm/time.h8
-rw-r--r--arch/openrisc/kernel/Makefile2
-rw-r--r--arch/openrisc/kernel/smp.c3
-rw-r--r--arch/openrisc/kernel/sync-timer.c120
-rw-r--r--arch/openrisc/kernel/time.c15
5 files changed, 145 insertions, 3 deletions
diff --git a/arch/openrisc/include/asm/time.h b/arch/openrisc/include/asm/time.h
index fe83a34a7d68..313ee975774b 100644
--- a/arch/openrisc/include/asm/time.h
+++ b/arch/openrisc/include/asm/time.h
@@ -12,4 +12,12 @@
extern void openrisc_clockevent_init(void);
+extern void openrisc_timer_set(unsigned long count);
+extern void openrisc_timer_set_next(unsigned long delta);
+
+#ifdef CONFIG_SMP
+extern void synchronise_count_master(int cpu);
+extern void synchronise_count_slave(int cpu);
+#endif
+
#endif /* __ASM_OR1K_TIME_H */
diff --git a/arch/openrisc/kernel/Makefile b/arch/openrisc/kernel/Makefile
index b4b51a07016a..9028e5a1fdd7 100644
--- a/arch/openrisc/kernel/Makefile
+++ b/arch/openrisc/kernel/Makefile
@@ -8,7 +8,7 @@ obj-y := setup.o or32_ksyms.o process.o dma.o \
traps.o time.o irq.o entry.o ptrace.o signal.o \
sys_call_table.o unwinder.o
-obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_SMP) += smp.o sync-timer.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_OF) += prom.o
diff --git a/arch/openrisc/kernel/smp.c b/arch/openrisc/kernel/smp.c
index 4763b8b9161e..4d80ce6fa045 100644
--- a/arch/openrisc/kernel/smp.c
+++ b/arch/openrisc/kernel/smp.c
@@ -100,6 +100,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
pr_crit("CPU%u: failed to start\n", cpu);
return -EIO;
}
+ synchronise_count_master(cpu);
return 0;
}
@@ -129,6 +130,8 @@ asmlinkage __init void secondary_start_kernel(void)
set_cpu_online(cpu, true);
complete(&cpu_running);
+ synchronise_count_slave(cpu);
+
local_irq_enable();
preempt_disable();
diff --git a/arch/openrisc/kernel/sync-timer.c b/arch/openrisc/kernel/sync-timer.c
new file mode 100644
index 000000000000..ed8d835caca1
--- /dev/null
+++ b/arch/openrisc/kernel/sync-timer.c
@@ -0,0 +1,120 @@
+/*
+ * OR1K timer synchronisation
+ *
+ * Based on work from MIPS implementation.
+ *
+ * All CPUs will have their count registers synchronised to the CPU0 next time
+ * value. This can cause a small timewarp for CPU0. All other CPU's should
+ * not have done anything significant (but they may have had interrupts
+ * enabled briefly - prom_smp_finish() should not be responsible for enabling
+ * interrupts...)
+ */
+
+#include <linux/kernel.h>
+#include <linux/irqflags.h>
+#include <linux/cpumask.h>
+
+#include <asm/time.h>
+#include <asm/timex.h>
+#include <linux/atomic.h>
+#include <asm/barrier.h>
+
+#include <asm/spr.h>
+
+static unsigned int initcount;
+static atomic_t count_count_start = ATOMIC_INIT(0);
+static atomic_t count_count_stop = ATOMIC_INIT(0);
+
+#define COUNTON 100
+#define NR_LOOPS 3
+
+void synchronise_count_master(int cpu)
+{
+ int i;
+ unsigned long flags;
+
+ pr_info("Synchronize counters for CPU %u: ", cpu);
+
+ local_irq_save(flags);
+
+ /*
+ * We loop a few times to get a primed instruction cache,
+ * then the last pass is more or less synchronised and
+ * the master and slaves each set their cycle counters to a known
+ * value all at once. This reduces the chance of having random offsets
+ * between the processors, and guarantees that the maximum
+ * delay between the cycle counters is never bigger than
+ * the latency of information-passing (cachelines) between
+ * two CPUs.
+ */
+
+ for (i = 0; i < NR_LOOPS; i++) {
+ /* slaves loop on '!= 2' */
+ while (atomic_read(&count_count_start) != 1)
+ mb();
+ atomic_set(&count_count_stop, 0);
+ smp_wmb();
+
+ /* Let the slave writes its count register */
+ atomic_inc(&count_count_start);
+
+ /* Count will be initialised to current timer */
+ if (i == 1)
+ initcount = get_cycles();
+
+ /*
+ * Everyone initialises count in the last loop:
+ */
+ if (i == NR_LOOPS-1)
+ openrisc_timer_set(initcount);
+
+ /*
+ * Wait for slave to leave the synchronization point:
+ */
+ while (atomic_read(&count_count_stop) != 1)
+ mb();
+ atomic_set(&count_count_start, 0);
+ smp_wmb();
+ atomic_inc(&count_count_stop);
+ }
+ /* Arrange for an interrupt in a short while */
+ openrisc_timer_set_next(COUNTON);
+
+ local_irq_restore(flags);
+
+ /*
+ * i386 code reported the skew here, but the
+ * count registers were almost certainly out of sync
+ * so no point in alarming people
+ */
+ pr_cont("done.\n");
+}
+
+void synchronise_count_slave(int cpu)
+{
+ int i;
+
+ /*
+ * Not every cpu is online at the time this gets called,
+ * so we first wait for the master to say everyone is ready
+ */
+
+ for (i = 0; i < NR_LOOPS; i++) {
+ atomic_inc(&count_count_start);
+ while (atomic_read(&count_count_start) != 2)
+ mb();
+
+ /*
+ * Everyone initialises count in the last loop:
+ */
+ if (i == NR_LOOPS-1)
+ openrisc_timer_set(initcount);
+
+ atomic_inc(&count_count_stop);
+ while (atomic_read(&count_count_stop) != 2)
+ mb();
+ }
+ /* Arrange for an interrupt in a short while */
+ openrisc_timer_set_next(COUNTON);
+}
+#undef NR_LOOPS
diff --git a/arch/openrisc/kernel/time.c b/arch/openrisc/kernel/time.c
index ab04eaedbf8d..6baecea27080 100644
--- a/arch/openrisc/kernel/time.c
+++ b/arch/openrisc/kernel/time.c
@@ -27,8 +27,14 @@
#include <asm/cpuinfo.h>
-static int openrisc_timer_set_next_event(unsigned long delta,
- struct clock_event_device *dev)
+/* Test the timer ticks to count, used in sync routine */
+inline void openrisc_timer_set(unsigned long count)
+{
+ mtspr(SPR_TTCR, count);
+}
+
+/* Set the timer to trigger in delta cycles */
+inline void openrisc_timer_set_next(unsigned long delta)
{
u32 c;
@@ -44,7 +50,12 @@ static int openrisc_timer_set_next_event(unsigned long delta,
* Keep timer in continuous mode always.
*/
mtspr(SPR_TTMR, SPR_TTMR_CR | SPR_TTMR_IE | c);
+}
+static int openrisc_timer_set_next_event(unsigned long delta,
+ struct clock_event_device *dev)
+{
+ openrisc_timer_set_next(delta);
return 0;
}