msm: hotplug: support cpu hotplug on msm

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

2 files changed, 93 insertions, 0 deletions

diff --git a/arch/arm/mach-msm/Makefile b/arch/arm/mach-msm/Makefile
index 5765ef1e60fc..c673e5fdabf9 100644
--- a/arch/arm/mach-msm/Makefile
+++ b/arch/arm/mach-msm/Makefile
@@ -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
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;
+}