msm: hotplug: support cpu hotplug on msm

Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>

1 files changed, 91 insertions, 0 deletions

diff --git a/arch/arm/mach-msm/hotplug.c b/arch/arm/mach-msm/hotplug.c
new file mode 100644
index 00000000000..5a31f70dfb8
--- /dev/null
+++ b/arch/arm/mach-msm/hotplug.c
@@ -0,0 +1,91 @@
+/*
+ *  Copyright (C) 2002 ARM Ltd.
+ *  All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/smp.h>
+
+#include <asm/cacheflush.h>
+
+extern volatile int pen_release;
+
+static inline void cpu_enter_lowpower(void)
+{
+	/* Just flush the cache. Changing the coherency is not yet
+	 * available on msm. */
+	flush_cache_all();
+}
+
+static inline void cpu_leave_lowpower(void)
+{
+}
+
+static inline void platform_do_lowpower(unsigned int cpu)
+{
+	/* Just enter wfi for now. TODO: Properly shut off the cpu. */
+	for (;;) {
+		/*
+		 * here's the WFI
+		 */
+		asm("wfi"
+		    :
+		    :
+		    : "memory", "cc");
+
+		if (pen_release == cpu) {
+			/*
+			 * OK, proper wakeup, we're done
+			 */
+			break;
+		}
+
+		/*
+		 * getting here, means that we have come out of WFI without
+		 * having been woken up - this shouldn't happen
+		 *
+		 * The trouble is, letting people know about this is not really
+		 * possible, since we are currently running incoherently, and
+		 * therefore cannot safely call printk() or anything else
+		 */
+		pr_debug("CPU%u: spurious wakeup call\n", cpu);
+	}
+}
+
+int platform_cpu_kill(unsigned int cpu)
+{
+	return 1;
+}
+
+/*
+ * platform-specific code to shutdown a CPU
+ *
+ * Called with IRQs disabled
+ */
+void platform_cpu_die(unsigned int cpu)
+{
+	/*
+	 * we're ready for shutdown now, so do it
+	 */
+	cpu_enter_lowpower();
+	platform_do_lowpower(cpu);
+
+	/*
+	 * bring this CPU back into the world of cache
+	 * coherency, and then restore interrupts
+	 */
+	cpu_leave_lowpower();
+}
+
+int platform_cpu_disable(unsigned int cpu)
+{
+	/*
+	 * we don't allow CPU 0 to be shutdown (it is still too special
+	 * e.g. clock tick interrupts)
+	 */
+	return cpu == 0 ? -EPERM : 0;
+}