sparc32, sun4d: Implemented SMP IPIs support for SUN4D machines

The sun4d does not seem to have a distingstion between soft and hard
IRQs. When generating IPIs the generated IRQ looks like a hard IRQ,
this patch adds a "IPI check" in the sun4d irq trap handler at a
predefined IRQ number (SUN4D_IPI_IRQ). Before generating an IPI
a per-cpu memory structure is modified for the "IPI check" to
successfully detect a IPI request to a specific processor, the check
clears the IPI work requested.

All three IPIs (resched, single and cpu-mask) use the same IRQ
number.

The IPI IRQ should preferrably be on a separate IRQ and definitly
not shared with IRQ handlers requesting IRQ with IRQF_SHARED.

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

3 files changed, 94 insertions, 0 deletions

diff --git a/arch/sparc/kernel/irq.h b/arch/sparc/kernel/irq.h
index a189c273f638..100b9c204e78 100644
--- a/arch/sparc/kernel/irq.h
+++ b/arch/sparc/kernel/irq.h
@@ -86,4 +86,10 @@ BTFIXUPDEF_CALL(void, set_irq_udt, int)
 #define set_cpu_int(cpu,level) BTFIXUP_CALL(set_cpu_int)(cpu,level)
 #define clear_cpu_int(cpu,level) BTFIXUP_CALL(clear_cpu_int)(cpu,level)
 #define set_irq_udt(cpu) BTFIXUP_CALL(set_irq_udt)(cpu)
+
+/* All SUN4D IPIs are sent on this IRQ, may be shared with hard IRQs */
+#define SUN4D_IPI_IRQ 14
+
+extern void sun4d_ipi_interrupt(void);
+
 #endif
diff --git a/arch/sparc/kernel/sun4d_irq.c b/arch/sparc/kernel/sun4d_irq.c
index b830914e32d3..a9ea60eb2c10 100644
--- a/arch/sparc/kernel/sun4d_irq.c
+++ b/arch/sparc/kernel/sun4d_irq.c
@@ -156,6 +156,15 @@ void sun4d_handler_irq(int pil, struct pt_regs *regs)
 
         cc_set_iclr(1 << pil);
 
+#ifdef CONFIG_SMP
+        /*
+         * Check IPI data structures after IRQ has been cleared. Hard and Soft
+         * IRQ can happen at the same time, so both cases are always handled.
+         */
+        if (pil == SUN4D_IPI_IRQ)
+                sun4d_ipi_interrupt();
+#endif
+
         old_regs = set_irq_regs(regs);
         irq_enter();
         if (sbusl == 0) {
diff --git a/arch/sparc/kernel/sun4d_smp.c b/arch/sparc/kernel/sun4d_smp.c
index 38423a05ae41..30ca6245692f 100644
--- a/arch/sparc/kernel/sun4d_smp.c
+++ b/arch/sparc/kernel/sun4d_smp.c
@@ -32,6 +32,7 @@ static inline unsigned long sun4d_swap(volatile unsigned long *ptr, unsigned lon
         return val;
 }
 
+static void smp4d_ipi_init(void);
 static void smp_setup_percpu_timer(void);
 
 static unsigned char cpu_leds[32];
@@ -118,6 +119,7 @@ void __cpuinit smp4d_callin(void)
  */
 void __init smp4d_boot_cpus(void)
 {
+        smp4d_ipi_init();
         if (boot_cpu_id)
                 current_set[0] = NULL;
         smp_setup_percpu_timer();
@@ -189,6 +191,80 @@ void __init smp4d_smp_done(void)
         sun4d_distribute_irqs();
 }
 
+/* Memory structure giving interrupt handler information about IPI generated */
+struct sun4d_ipi_work {
+        int single;
+        int msk;
+        int resched;
+};
+
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct sun4d_ipi_work, sun4d_ipi_work);
+
+/* Initialize IPIs on the SUN4D SMP machine */
+static void __init smp4d_ipi_init(void)
+{
+        int cpu;
+        struct sun4d_ipi_work *work;
+
+        printk(KERN_INFO "smp4d: setup IPI at IRQ %d\n", SUN4D_IPI_IRQ);
+
+        for_each_possible_cpu(cpu) {
+                work = &per_cpu(sun4d_ipi_work, cpu);
+                work->single = work->msk = work->resched = 0;
+        }
+}
+
+void sun4d_ipi_interrupt(void)
+{
+        struct sun4d_ipi_work *work = &__get_cpu_var(sun4d_ipi_work);
+
+        if (work->single) {
+                work->single = 0;
+                smp_call_function_single_interrupt();
+        }
+        if (work->msk) {
+                work->msk = 0;
+                smp_call_function_interrupt();
+        }
+        if (work->resched) {
+                work->resched = 0;
+                smp_resched_interrupt();
+        }
+}
+
+static void smp4d_ipi_single(int cpu)
+{
+        struct sun4d_ipi_work *work = &per_cpu(sun4d_ipi_work, cpu);
+
+        /* Mark work */
+        work->single = 1;
+
+        /* Generate IRQ on the CPU */
+        sun4d_send_ipi(cpu, SUN4D_IPI_IRQ);
+}
+
+static void smp4d_ipi_mask_one(int cpu)
+{
+        struct sun4d_ipi_work *work = &per_cpu(sun4d_ipi_work, cpu);
+
+        /* Mark work */
+        work->msk = 1;
+
+        /* Generate IRQ on the CPU */
+        sun4d_send_ipi(cpu, SUN4D_IPI_IRQ);
+}
+
+static void smp4d_ipi_resched(int cpu)
+{
+        struct sun4d_ipi_work *work = &per_cpu(sun4d_ipi_work, cpu);
+
+        /* Mark work */
+        work->resched = 1;
+
+        /* Generate IRQ on the CPU (any IRQ will cause resched) */
+        sun4d_send_ipi(cpu, SUN4D_IPI_IRQ);
+}
+
 static struct smp_funcall {
         smpfunc_t func;
         unsigned long arg1;
@@ -354,6 +430,9 @@ void __init sun4d_init_smp(void)
         BTFIXUPSET_BLACKBOX(load_current, smp4d_blackbox_current);
         BTFIXUPSET_CALL(smp_cross_call, smp4d_cross_call, BTFIXUPCALL_NORM);
         BTFIXUPSET_CALL(__hard_smp_processor_id, __smp4d_processor_id, BTFIXUPCALL_NORM);
+        BTFIXUPSET_CALL(smp_ipi_resched, smp4d_ipi_resched, BTFIXUPCALL_NORM);
+        BTFIXUPSET_CALL(smp_ipi_single, smp4d_ipi_single, BTFIXUPCALL_NORM);
+        BTFIXUPSET_CALL(smp_ipi_mask_one, smp4d_ipi_mask_one, BTFIXUPCALL_NORM);
 
         for (i = 0; i < NR_CPUS; i++) {
                 ccall_info.processors_in[i] = 1;