msm: hotplug: support cpu hotplug on msm
Jeff Ohlstein [Thu, 2 Dec 2010 20:11:27 +0000 (12:11 -0800)]
Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>

arch/arm/mach-msm/Makefile
arch/arm/mach-msm/hotplug.c [new file with mode: 0644]

index 5765ef1..c673e5f 100644 (file)
@@ -20,6 +20,8 @@ obj-$(CONFIG_MSM_SMD) += smd.o smd_debug.o
 obj-$(CONFIG_MSM_SMD) += last_radio_log.o
 obj-$(CONFIG_MSM_SCM) += scm.o scm-boot.o
 
+obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
+
 obj-$(CONFIG_MACH_TROUT) += board-trout.o board-trout-gpio.o board-trout-mmc.o devices-msm7x00.o
 obj-$(CONFIG_MACH_TROUT) += board-trout.o board-trout-gpio.o board-trout-mmc.o board-trout-panel.o devices-msm7x00.o
 obj-$(CONFIG_MACH_HALIBUT) += board-halibut.o devices-msm7x00.o
diff --git a/arch/arm/mach-msm/hotplug.c b/arch/arm/mach-msm/hotplug.c
new file mode 100644 (file)
index 0000000..5a31f70
--- /dev/null
@@ -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;
+}