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authorJeff Ohlstein <johlstei@codeaurora.org>2010-12-02 12:11:27 -0800
committerDavid Brown <davidb@codeaurora.org>2011-01-07 15:54:44 -0800
commit9f1890a5de2a5fcf4fd9ffa3115047eed834349c (patch)
tree8f7f7931a22399409057824f1f912fd6f8a86112 /arch/arm/mach-msm/hotplug.c
parent94790ec25fdd51dc4126cc176f2e104f80f87fcb (diff)
msm: hotplug: support cpu hotplug on msm
Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org> Signed-off-by: David Brown <davidb@codeaurora.org>
Diffstat (limited to 'arch/arm/mach-msm/hotplug.c')
-rw-r--r--arch/arm/mach-msm/hotplug.c91
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 000000000000..5a31f70dfb8e
--- /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;
+}