[POWERPC] ps3: cleanup interrupt bmp routines

Change the PS3 interrupt bitmask routines to be lockless.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 38 insertions, 47 deletions

diff --git a/arch/powerpc/platforms/ps3/interrupt.c b/arch/powerpc/platforms/ps3/interrupt.c
index 7a4ca056dd3a..d3c97fbff7ef 100644
--- a/arch/powerpc/platforms/ps3/interrupt.c
+++ b/arch/powerpc/platforms/ps3/interrupt.c
@@ -380,34 +380,50 @@ static void dump_bmp(struct ps3_private* pd) {};
 
 static void ps3_chip_mask(unsigned int virq)
 {
-        unsigned long flags;
         struct ps3_private *pd = get_irq_chip_data(virq);
+        unsigned long bit = 0x8000000000000000UL >> virq;
+        unsigned long *p = &pd->bmp.mask;
+        unsigned long old;
+        unsigned long flags;
 
         pr_debug("%s:%d: cpu %u, virq %d\n", __func__, __LINE__, pd->cpu, virq);
 
-        BUG_ON(virq < NUM_ISA_INTERRUPTS);
-        BUG_ON(virq > PS3_PLUG_MAX);
+        local_irq_save(flags);
+        asm volatile(
+                     "1:        ldarx %0,0,%3\n"
+                     "andc      %0,%0,%2\n"
+                     "stdcx.    %0,0,%3\n"
+                     "bne-      1b"
+                     : "=&r" (old), "+m" (*p)
+                     : "r" (bit), "r" (p)
+                     : "cc" );
 
-        spin_lock_irqsave(&pd->bmp.lock, flags);
-        pd->bmp.mask &= ~(0x8000000000000000UL >> virq);
         lv1_did_update_interrupt_mask(pd->node, pd->cpu);
-        spin_unlock_irqrestore(&pd->bmp.lock, flags);
+        local_irq_restore(flags);
 }
 
 static void ps3_chip_unmask(unsigned int virq)
 {
-        unsigned long flags;
         struct ps3_private *pd = get_irq_chip_data(virq);
+        unsigned long bit = 0x8000000000000000UL >> virq;
+        unsigned long *p = &pd->bmp.mask;
+        unsigned long old;
+        unsigned long flags;
 
         pr_debug("%s:%d: cpu %u, virq %d\n", __func__, __LINE__, pd->cpu, virq);
 
-        BUG_ON(virq < NUM_ISA_INTERRUPTS);
-        BUG_ON(virq > PS3_PLUG_MAX);
+        local_irq_save(flags);
+        asm volatile(
+                     "1:        ldarx %0,0,%3\n"
+                     "or        %0,%0,%2\n"
+                     "stdcx.    %0,0,%3\n"
+                     "bne-      1b"
+                     : "=&r" (old), "+m" (*p)
+                     : "r" (bit), "r" (p)
+                     : "cc" );
 
-        spin_lock_irqsave(&pd->bmp.lock, flags);
-        pd->bmp.mask |= (0x8000000000000000UL >> virq);
         lv1_did_update_interrupt_mask(pd->node, pd->cpu);
-        spin_unlock_irqrestore(&pd->bmp.lock, flags);
+        local_irq_restore(flags);
 }
 
 static void ps3_chip_eoi(unsigned int virq)
@@ -481,46 +497,21 @@ void __init ps3_register_ipi_debug_brk(unsigned int cpu, unsigned int virq)
                 cpu, virq, pd->bmp.ipi_debug_brk_mask);
 }
 
-static int bmp_get_and_clear_status_bit(struct ps3_bmp *m)
+unsigned int ps3_get_irq(void)
 {
-        unsigned long flags;
-        unsigned int bit;
-        unsigned long x;
-
-        spin_lock_irqsave(&m->lock, flags);
+        struct ps3_private *pd = &__get_cpu_var(ps3_private);
+        unsigned long x = (pd->bmp.status & pd->bmp.mask);
+        unsigned int plug;
 
         /* check for ipi break first to stop this cpu ASAP */
 
-        if (m->status & m->ipi_debug_brk_mask) {
-                m->status &= ~m->ipi_debug_brk_mask;
-                spin_unlock_irqrestore(&m->lock, flags);
-                return __ilog2(m->ipi_debug_brk_mask);
-        }
-
-        x = (m->status & m->mask);
-
-        for (bit = NUM_ISA_INTERRUPTS, x <<= bit; x; bit++, x <<= 1)
-                if (x & 0x8000000000000000UL) {
-                        m->status &= ~(0x8000000000000000UL >> bit);
-                        spin_unlock_irqrestore(&m->lock, flags);
-                        return bit;
-                }
-
-        spin_unlock_irqrestore(&m->lock, flags);
-
-        pr_debug("%s:%d: not found\n", __func__, __LINE__);
-        return -1;
-}
-
-unsigned int ps3_get_irq(void)
-{
-        int plug;
-
-        struct ps3_private *pd = &__get_cpu_var(ps3_private);
+        if (x & pd->bmp.ipi_debug_brk_mask)
+                x &= pd->bmp.ipi_debug_brk_mask;
 
-        plug = bmp_get_and_clear_status_bit(&pd->bmp);
+        asm volatile("cntlzd %0,%1" : "=r" (plug) : "r" (x));
+        plug &= 0x3f;
 
-        if (plug < 1) {
+        if (unlikely(plug) == NO_IRQ) {
                 pr_debug("%s:%d: no plug found: cpu %u\n", __func__, __LINE__,
                         pd->cpu);
                 dump_bmp(&per_cpu(ps3_private, 0));
@@ -529,7 +520,7 @@ unsigned int ps3_get_irq(void)
         }
 
 #if defined(DEBUG)
-        if (plug < NUM_ISA_INTERRUPTS || plug > PS3_PLUG_MAX) {
+        if (unlikely(plug < NUM_ISA_INTERRUPTS || plug > PS3_PLUG_MAX)) {
                 dump_bmp(&per_cpu(ps3_private, 0));
                 dump_bmp(&per_cpu(ps3_private, 1));
                 BUG();