[MIPS] Add smp_call_function_single()

In the other archs, there is more factoring of smp call code, and more care
in the use of get_cpu(). That can be a follow-up MIPS patch.

Signed-off-by: Peter Watkins <pwatkins@sicortex.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 04bbbd8d91a..73b0dab0266 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -194,6 +194,61 @@ void smp_call_function_interrupt(void)
         }
 }
 
+int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
+                             int retry, int wait)
+{
+        struct call_data_struct data;
+        int me;
+
+        /*
+         * Can die spectacularly if this CPU isn't yet marked online
+         */
+        if (!cpu_online(cpu))
+                return 0;
+
+        me = get_cpu();
+        BUG_ON(!cpu_online(me));
+
+        if (cpu == me) {
+                local_irq_disable();
+                func(info);
+                local_irq_enable();
+                put_cpu();
+                return 0;
+        }
+
+        /* Can deadlock when called with interrupts disabled */
+        WARN_ON(irqs_disabled());
+
+        data.func = func;
+        data.info = info;
+        atomic_set(&data.started, 0);
+        data.wait = wait;
+        if (wait)
+                atomic_set(&data.finished, 0);
+
+        spin_lock(&smp_call_lock);
+        call_data = &data;
+        smp_mb();
+
+        /* Send a message to the other CPU */
+        core_send_ipi(cpu, SMP_CALL_FUNCTION);
+
+        /* Wait for response */
+        /* FIXME: lock-up detection, backtrace on lock-up */
+        while (atomic_read(&data.started) != 1)
+                barrier();
+
+        if (wait)
+                while (atomic_read(&data.finished) != 1)
+                        barrier();
+        call_data = NULL;
+        spin_unlock(&smp_call_lock);
+
+        put_cpu();
+        return 0;
+}
+
 static void stop_this_cpu(void *dummy)
 {
         /*