powerpc: Add support for using doorbells for SMP IPI

The e500mc supports the new msgsnd/doorbell mechanisms that were added in
the Power ISA 2.05 architecture.  We use the normal level doorbell for
doing SMP IPIs at this point.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

6 files changed, 117 insertions, 3 deletions

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4911104791c3..fca161190db4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -145,6 +145,7 @@ extern const char *powerpc_base_platform;
 #define CPU_FTR_USE_TB                  ASM_CONST(0x0000000000000040)
 #define CPU_FTR_L2CSR                   ASM_CONST(0x0000000000000080)
 #define CPU_FTR_601                     ASM_CONST(0x0000000000000100)
+#define CPU_FTR_DBELL                   ASM_CONST(0x0000000000000200)
 #define CPU_FTR_CAN_NAP                 ASM_CONST(0x0000000000000400)
 #define CPU_FTR_L3CR                    ASM_CONST(0x0000000000000800)
 #define CPU_FTR_L3_DISABLE_NAP          ASM_CONST(0x0000000000001000)
@@ -373,7 +374,8 @@ extern const char *powerpc_base_platform;
             CPU_FTR_NODSISRALIGN | CPU_FTR_NOEXECUTE)
 #define CPU_FTRS_E500MC (CPU_FTR_MAYBE_CAN_DOZE | CPU_FTR_USE_TB | \
             CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_NODSISRALIGN | \
-            CPU_FTR_L2CSR | CPU_FTR_LWSYNC | CPU_FTR_NOEXECUTE)
+            CPU_FTR_L2CSR | CPU_FTR_LWSYNC | CPU_FTR_NOEXECUTE | \
+            CPU_FTR_DBELL)
 #define CPU_FTRS_GENERIC_32     (CPU_FTR_COMMON | CPU_FTR_NODSISRALIGN)
 
 /* 64-bit CPUs */
diff --git a/arch/powerpc/include/asm/dbell.h b/arch/powerpc/include/asm/dbell.h
new file mode 100644
index 000000000000..501189a543d1
--- /dev/null
+++ b/arch/powerpc/include/asm/dbell.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2009 Freescale Semicondutor, 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.
+ *
+ * provides masks and opcode images for use by code generation, emulation
+ * and for instructions that older assemblers might not know about
+ */
+#ifndef _ASM_POWERPC_DBELL_H
+#define _ASM_POWERPC_DBELL_H
+
+#include <linux/smp.h>
+#include <linux/threads.h>
+
+#include <asm/ppc-opcode.h>
+
+#define PPC_DBELL_MSG_BRDCAST   (0x04000000)
+#define PPC_DBELL_TYPE(x)       (((x) & 0xf) << 28)
+enum ppc_dbell {
+        PPC_DBELL = 0,          /* doorbell */
+        PPC_DBELL_CRIT = 1,     /* critical doorbell */
+        PPC_G_DBELL = 2,        /* guest doorbell */
+        PPC_G_DBELL_CRIT = 3,   /* guest critical doorbell */
+        PPC_G_DBELL_MC = 4,     /* guest mcheck doorbell */
+};
+
+#ifdef CONFIG_SMP
+extern unsigned long dbell_smp_message[NR_CPUS];
+extern void smp_dbell_message_pass(int target, int msg);
+#endif
+
+static inline void ppc_msgsnd(enum ppc_dbell type, u32 flags, u32 tag)
+{
+        u32 msg = PPC_DBELL_TYPE(type) | (flags & PPC_DBELL_MSG_BRDCAST) |
+                        (tag & 0x07ffffff);
+
+        __asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
+}
+
+#endif /* _ASM_POWERPC_DBELL_H */
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 583ba6493a62..dfec3d2790b2 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -59,7 +59,7 @@ obj-$(CONFIG_HIBERNATION)	+= swsusp.o suspend.o \
 obj64-$(CONFIG_HIBERNATION)     += swsusp_asm64.o
 obj-$(CONFIG_MODULES)           += module.o module_$(CONFIG_WORD_SIZE).o
 obj-$(CONFIG_44x)               += cpu_setup_44x.o
-obj-$(CONFIG_FSL_BOOKE)         += cpu_setup_fsl_booke.o
+obj-$(CONFIG_FSL_BOOKE)         += cpu_setup_fsl_booke.o dbell.o
 
 extra-$(CONFIG_PPC_STD_MMU)     := head_32.o
 extra-$(CONFIG_PPC64)           := head_64.o
diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/dbell.c
new file mode 100644
index 000000000000..1493734cd871
--- /dev/null
+++ b/arch/powerpc/kernel/dbell.c
@@ -0,0 +1,44 @@
+/*
+ * 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 <asm/dbell.h>
+
+#ifdef CONFIG_SMP
+unsigned long dbell_smp_message[NR_CPUS];
+
+void smp_dbell_message_pass(int target, int msg)
+{
+        int i;
+
+        if(target < NR_CPUS) {
+                set_bit(msg, &dbell_smp_message[target]);
+                ppc_msgsnd(PPC_DBELL, 0, target);
+        }
+        else if(target == MSG_ALL_BUT_SELF) {
+                for_each_online_cpu(i) {
+                        if (i == smp_processor_id())
+                                continue;
+                        set_bit(msg, &dbell_smp_message[i]);
+                        ppc_msgsnd(PPC_DBELL, 0, i);
+                }
+        }
+        else { /* target == MSG_ALL */
+                for_each_online_cpu(i)
+                        set_bit(msg, &dbell_smp_message[i]);
+                ppc_msgsnd(PPC_DBELL, PPC_DBELL_MSG_BRDCAST, 0);
+        }
+}
+#endif
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index 4ea6e1a7e4b9..4c22620d009b 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -698,7 +698,9 @@ interrupt_base:
         /* Performance Monitor */
         EXCEPTION(0x2060, PerformanceMonitor, performance_monitor_exception, EXC_XFER_STD)
 
-        EXCEPTION(0x2070, Doorbell, unknown_exception, EXC_XFER_STD)
+        EXCEPTION(0x2070, Doorbell, doorbell_exception, EXC_XFER_STD)
+
+        CRITICAL_EXCEPTION(0x2080, CriticalDoorbell, unknown_exception)
 
         /* Debug Interrupt */
         DEBUG_DEBUG_EXCEPTION
@@ -921,6 +923,8 @@ _GLOBAL(__setup_e500mc_ivors)
         mtspr   SPRN_IVOR35,r3
         li      r3,Doorbell@l
         mtspr   SPRN_IVOR36,r3
+        li      r3,CriticalDoorbell@l
+        mtspr   SPRN_IVOR37,r3
         sync
         blr
 
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 970d66ec4657..678fbff0d206 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -53,6 +53,9 @@
 #endif
 #include <asm/kexec.h>
 #include <asm/ppc-opcode.h>
+#ifdef CONFIG_FSL_BOOKE
+#include <asm/dbell.h>
+#endif
 
 #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
 int (*__debugger)(struct pt_regs *regs);
@@ -1122,6 +1125,24 @@ void vsx_assist_exception(struct pt_regs *regs)
 #endif /* CONFIG_VSX */
 
 #ifdef CONFIG_FSL_BOOKE
+
+void doorbell_exception(struct pt_regs *regs)
+{
+#ifdef CONFIG_SMP
+        int cpu = smp_processor_id();
+        int msg;
+
+        if (num_online_cpus() < 2)
+                return;
+
+        for (msg = 0; msg < 4; msg++)
+                if (test_and_clear_bit(msg, &dbell_smp_message[cpu]))
+                        smp_message_recv(msg);
+#else
+        printk(KERN_WARNING "Received doorbell on non-smp system\n");
+#endif
+}
+
 void CacheLockingException(struct pt_regs *regs, unsigned long address,
                            unsigned long error_code)
 {