Fixed MTP to work with TWRP

arch/powerpc/kernel/dbell.c

@@ -0,0 +1,57 @@
+/*
+ * Author: Kumar Gala <galak@kernel.crashing.org>
+ *
+ * Copyright 2009 Freescale Semiconductor Inc.
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/threads.h>
+#include <linux/hardirq.h>
+
+#include <asm/dbell.h>
+#include <asm/irq_regs.h>
+
+#ifdef CONFIG_SMP
+void doorbell_setup_this_cpu(void)
+{
+	unsigned long tag = mfspr(SPRN_DOORBELL_CPUTAG) & PPC_DBELL_TAG_MASK;
+
+	smp_muxed_ipi_set_data(smp_processor_id(), tag);
+}
+
+void doorbell_cause_ipi(int cpu, unsigned long data)
+{
+	/* Order previous accesses vs. msgsnd, which is treated as a store */
+	mb();
+	ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, data);
+}
+
+void doorbell_exception(struct pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	irq_enter();
+
+	may_hard_irq_enable();
+
+	__get_cpu_var(irq_stat).doorbell_irqs++;
+
+	smp_ipi_demux();
+
+	irq_exit();
+	set_irq_regs(old_regs);
+}
+#else /* CONFIG_SMP */
+void doorbell_exception(struct pt_regs *regs)
+{
+	printk(KERN_WARNING "Received doorbell on non-smp system\n");
+}
+#endif /* CONFIG_SMP */
+