sparc32, sun4m: Implemented SMP IPIs support for SUN4M machines

Implement the three IPIs (resched, single and cpu-mask) generation
and interrupt handler catch. The sun4m has 15 soft-IRQs and three
of them is used with this patch, the three IPIs was previously
implemented with the cross-call IRQ15 which does not work with
locking routines such as spinlocks because IRQ15 is NMI, it may
cause deadlock.

The IRQ trap handler code assumes (in the same spritit as the old
it seems) that hard interrupts will be generated until handled
(level), when a IRQ happens the IRQ pending register is checked
for pending soft-IRQs. When both hard and soft IRQ happens at the
same time only soft-IRQs are handled.

The old code implemented a soft-IRQ traphandler at IRQ14 which
called smp_reschedule_irq which in turn called set_need_resched.
It seems to be an old relic and is replaced with the interrupt
traphander exit code RESTORE_ALL, it calls schedule() when
appropriate.

Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 29 insertions, 0 deletions

diff --git a/arch/sparc/kernel/sun4m_smp.c b/arch/sparc/kernel/sun4m_smp.c
index 5545d10d50c..e2e687312e2 100644
--- a/arch/sparc/kernel/sun4m_smp.c
+++ b/arch/sparc/kernel/sun4m_smp.c
@@ -15,6 +15,9 @@
 #include "irq.h"
 #include "kernel.h"
 
+#define IRQ_IPI_SINGLE		12
+#define IRQ_IPI_MASK		13
+#define IRQ_IPI_RESCHED		14
 #define IRQ_CROSS_CALL		15
 
 static inline unsigned long
@@ -26,6 +29,7 @@ swap_ulong(volatile unsigned long *ptr, unsigned long val)
 	return val;
 }
 
+static void smp4m_ipi_init(void);
 static void smp_setup_percpu_timer(void);
 
 void __cpuinit smp4m_callin(void)
@@ -81,6 +85,7 @@ void __cpuinit smp4m_callin(void)
  */
 void __init smp4m_boot_cpus(void)
 {
+	smp4m_ipi_init();
 	smp_setup_percpu_timer();
 	local_flush_cache_all();
 }
@@ -148,6 +153,27 @@ void __init smp4m_smp_done(void)
 	/* Ok, they are spinning and ready to go. */
 }
 
+
+/* Initialize IPIs on the SUN4M SMP machine */
+static void __init smp4m_ipi_init(void)
+{
+}
+
+static void smp4m_ipi_resched(int cpu)
+{
+	set_cpu_int(cpu, IRQ_IPI_RESCHED);
+}
+
+static void smp4m_ipi_single(int cpu)
+{
+	set_cpu_int(cpu, IRQ_IPI_SINGLE);
+}
+
+static void smp4m_ipi_mask_one(int cpu)
+{
+	set_cpu_int(cpu, IRQ_IPI_MASK);
+}
+
 static struct smp_funcall {
 	smpfunc_t func;
 	unsigned long arg1;
@@ -290,4 +316,7 @@ void __init sun4m_init_smp(void)
 	BTFIXUPSET_BLACKBOX(load_current, smp4m_blackbox_current);
 	BTFIXUPSET_CALL(smp_cross_call, smp4m_cross_call, BTFIXUPCALL_NORM);
 	BTFIXUPSET_CALL(__hard_smp_processor_id, __smp4m_processor_id, BTFIXUPCALL_NORM);
+	BTFIXUPSET_CALL(smp_ipi_resched, smp4m_ipi_resched, BTFIXUPCALL_NORM);
+	BTFIXUPSET_CALL(smp_ipi_single, smp4m_ipi_single, BTFIXUPCALL_NORM);
+	BTFIXUPSET_CALL(smp_ipi_mask_one, smp4m_ipi_mask_one, BTFIXUPCALL_NORM);
 }