powerpc: Consolidate ipi message mux and demux

Consolidate the mux and demux of ipi messages into smp.c and call
a new smp_ops callback to actually trigger the ipi.

The powerpc architecture code is optimised for having 4 distinct
ipi triggers, which are mapped to 4 distinct messages (ipi many, ipi
single, scheduler ipi, and enter debugger).  However, several interrupt
controllers only provide a single software triggered interrupt that
can be delivered to each cpu.  To resolve this limitation, each smp_ops
implementation created a per-cpu variable that is manipulated with atomic
bitops.  Since these lines will be contended they are optimialy marked as
shared_aligned and take a full cache line for each cpu.  Distro kernels
may have 2 or 3 of these in their config, each taking per-cpu space
even though at most one will be in use.

This consolidation removes smp_message_recv and replaces the single call
actions cases with direct calls from the common message recognition loop.
The complicated debugger ipi case with its muxed crash handling code is
moved to debug_ipi_action which is now called from the demux code (instead
of the multi-message action calling smp_message_recv).

I put a call to reschedule_action to increase the likelyhood of correctly
merging the anticipated scheduler_ipi() hook coming from the scheduler
tree; that single required call can be inlined later.

The actual message decode is a copy of the old pseries xics code with its
memory barriers and cache line spacing, augmented with a per-cpu unsigned
long based on the book-e doorbell code.  The optional data is set via a
callback from the implementation and is passed to the new cause-ipi hook
along with the logical cpu number.  While currently only the doorbell
implemntation uses this data it should be almost zero cost to retrieve and
pass it -- it adds a single register load for the argument from the same
cache line to which we just completed a store and the register is dead
on return from the call.  I extended the data element from unsigned int
to unsigned long in case some other code wanted to associate a pointer.

The doorbell check_self is replaced by a call to smp_muxed_ipi_resend,
conditioned on the CPU_DBELL feature.  The ifdef guard could be relaxed
to CONFIG_SMP but I left it with BOOKE for now.

Also, the doorbell interrupt vector for book-e was not calling irq_enter
and irq_exit, which throws off cpu accounting and causes code to not
realize it is running in interrupt context.  Add the missing calls.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

8 files changed, 32 insertions, 55 deletions

diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c
index fe3f6a3a5307..d6a93a10c0f5 100644
--- a/arch/powerpc/platforms/85xx/smp.c
+++ b/arch/powerpc/platforms/85xx/smp.c
@@ -235,8 +235,10 @@ void __init mpc85xx_smp_init(void)
 		smp_85xx_ops.message_pass = smp_mpic_message_pass;
 	}
 
-	if (cpu_has_feature(CPU_FTR_DBELL))
-		smp_85xx_ops.message_pass = doorbell_message_pass;
+	if (cpu_has_feature(CPU_FTR_DBELL)) {
+		smp_85xx_ops.message_pass = smp_muxed_ipi_message_pass;
+		smp_85xx_ops.cause_ipi = doorbell_cause_ipi;
+	}
 
 	BUG_ON(!smp_85xx_ops.message_pass);
 
diff --git a/arch/powerpc/platforms/cell/interrupt.c b/arch/powerpc/platforms/cell/interrupt.c
index 44cfd1bef89b..6a58744d66c3 100644
--- a/arch/powerpc/platforms/cell/interrupt.c
+++ b/arch/powerpc/platforms/cell/interrupt.c
@@ -196,8 +196,20 @@ static irqreturn_t iic_ipi_action(int irq, void *dev_id)
 {
 	int ipi = (int)(long)dev_id;
 
-	smp_message_recv(ipi);
-
+	switch(ipi) {
+	case PPC_MSG_CALL_FUNCTION:
+		generic_smp_call_function_interrupt();
+		break;
+	case PPC_MSG_RESCHEDULE:
+		/* Upcoming sched hook */
+		break;
+	case PPC_MSG_CALL_FUNC_SINGLE:
+		generic_smp_call_function_single_interrupt();
+		break;
+	case PPC_MSG_DEBUGGER_BREAK:
+		debug_ipi_action(0, NULL);
+		break;
+	}
 	return IRQ_HANDLED;
 }
 static void iic_request_ipi(int ipi, const char *name)
diff --git a/arch/powerpc/platforms/iseries/irq.c b/arch/powerpc/platforms/iseries/irq.c
index 375c21ca6602..b2103453eb01 100644
--- a/arch/powerpc/platforms/iseries/irq.c
+++ b/arch/powerpc/platforms/iseries/irq.c
@@ -42,7 +42,6 @@
 #include "irq.h"
 #include "pci.h"
 #include "call_pci.h"
-#include "smp.h"
 
 #ifdef CONFIG_PCI
 
@@ -316,7 +315,7 @@ unsigned int iSeries_get_irq(void)
 #ifdef CONFIG_SMP
 	if (get_lppaca()->int_dword.fields.ipi_cnt) {
 		get_lppaca()->int_dword.fields.ipi_cnt = 0;
-		iSeries_smp_message_recv();
+		smp_ipi_demux();
 	}
 #endif /* CONFIG_SMP */
 	if (hvlpevent_is_pending())
diff --git a/arch/powerpc/platforms/iseries/smp.c b/arch/powerpc/platforms/iseries/smp.c
index dcdbc5dc5aad..e3265adde5d3 100644
--- a/arch/powerpc/platforms/iseries/smp.c
+++ b/arch/powerpc/platforms/iseries/smp.c
@@ -42,26 +42,8 @@
 #include <asm/cputable.h>
 #include <asm/system.h>
 
-#include "smp.h"
-
-static unsigned long iSeries_smp_message[NR_CPUS];
-
-void iSeries_smp_message_recv(void)
-{
-	int cpu = smp_processor_id();
-	int msg;
-
-	if (num_online_cpus() < 2)
-		return;
-
-	for (msg = 0; msg < 4; msg++)
-		if (test_and_clear_bit(msg, &iSeries_smp_message[cpu]))
-			smp_message_recv(msg);
-}
-
-static void smp_iSeries_message_pass(int cpu, int msg)
+static void smp_iSeries_cause_ipi(int cpu, unsigned long data)
 {
-	set_bit(msg, &iSeries_smp_message[cpu]);
 	HvCall_sendIPI(&(paca[cpu]));
 }
 
@@ -93,7 +75,8 @@ static void __devinit smp_iSeries_setup_cpu(int nr)
 }
 
 static struct smp_ops_t iSeries_smp_ops = {
-	.message_pass = smp_iSeries_message_pass,
+	.message_pass = smp_muxed_ipi_message_pass,
+	.cause_ipi    = smp_iSeries_cause_ipi,
 	.probe        = smp_iSeries_probe,
 	.kick_cpu     = smp_iSeries_kick_cpu,
 	.setup_cpu    = smp_iSeries_setup_cpu,
diff --git a/arch/powerpc/platforms/iseries/smp.h b/arch/powerpc/platforms/iseries/smp.h
deleted file mode 100644
index d501f7de01e7..000000000000
--- a/arch/powerpc/platforms/iseries/smp.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef _PLATFORMS_ISERIES_SMP_H
-#define _PLATFORMS_ISERIES_SMP_H
-
-extern void iSeries_smp_message_recv(void);
-
-#endif	/* _PLATFORMS_ISERIES_SMP_H */
diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index c49e71926a54..a3401071abfb 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -156,28 +156,13 @@ static inline void psurge_clr_ipi(int cpu)
 /*
  * On powersurge (old SMP powermac architecture) we don't have
  * separate IPIs for separate messages like openpic does.  Instead
- * we have a bitmap for each processor, where a 1 bit means that
- * the corresponding message is pending for that processor.
- * Ideally each cpu's entry would be in a different cache line.
+ * use the generic demux helpers
  *  -- paulus.
  */
-static unsigned long psurge_smp_message[NR_CPUS];
-
 void psurge_smp_message_recv(void)
 {
-	int cpu = smp_processor_id();
-	int msg;
-
-	/* clear interrupt */
-	psurge_clr_ipi(cpu);
-
-	if (num_online_cpus() < 2)
-		return;
-
-	/* make sure there is a message there */
-	for (msg = 0; msg < 4; msg++)
-		if (test_and_clear_bit(msg, &psurge_smp_message[cpu]))
-			smp_message_recv(msg);
+	psurge_clr_ipi(smp_processor_id());
+	smp_ipi_demux();
 }
 
 irqreturn_t psurge_primary_intr(int irq, void *d)
@@ -186,9 +171,8 @@ irqreturn_t psurge_primary_intr(int irq, void *d)
 	return IRQ_HANDLED;
 }
 
-static void smp_psurge_message_pass(int cpu, int msg)
+static void smp_psurge_cause_ipi(int cpu, unsigned long data)
 {
-	set_bit(msg, &psurge_smp_message[cpu]);
 	psurge_set_ipi(cpu);
 }
 
@@ -428,7 +412,8 @@ void __init smp_psurge_give_timebase(void)
 
 /* PowerSurge-style Macs */
 struct smp_ops_t psurge_smp_ops = {
-	.message_pass	= smp_psurge_message_pass,
+	.message_pass	= smp_muxed_ipi_message_pass,
+	.cause_ipi	= smp_psurge_cause_ipi,
 	.probe		= smp_psurge_probe,
 	.kick_cpu	= smp_psurge_kick_cpu,
 	.setup_cpu	= smp_psurge_setup_cpu,
diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c
index 95f578158ff0..fbffd7e47ab8 100644
--- a/arch/powerpc/platforms/pseries/smp.c
+++ b/arch/powerpc/platforms/pseries/smp.c
@@ -207,7 +207,8 @@ static struct smp_ops_t pSeries_mpic_smp_ops = {
 };
 
 static struct smp_ops_t pSeries_xics_smp_ops = {
-	.message_pass	= NULL,	/* Filled at runtime by xics_smp_probe() */
+	.message_pass	= smp_muxed_ipi_message_pass,
+	.cause_ipi	= NULL,	/* Filled at runtime by xics_smp_probe() */
 	.probe		= xics_smp_probe,
 	.kick_cpu	= smp_pSeries_kick_cpu,
 	.setup_cpu	= smp_xics_setup_cpu,
diff --git a/arch/powerpc/platforms/wsp/smp.c b/arch/powerpc/platforms/wsp/smp.c
index c7b8db9ed9b3..9d20fa9d3710 100644
--- a/arch/powerpc/platforms/wsp/smp.c
+++ b/arch/powerpc/platforms/wsp/smp.c
@@ -75,7 +75,8 @@ static int __init smp_a2_probe(void)
 }
 
 static struct smp_ops_t a2_smp_ops = {
-	.message_pass	= doorbell_message_pass,
+	.message_pass	= smp_muxed_ipi_message_pass,
+	.cause_ipi	= doorbell_cause_ipi,
 	.probe		= smp_a2_probe,
 	.kick_cpu	= smp_a2_kick_cpu,
 	.setup_cpu	= smp_a2_setup_cpu,