[PATCH] powerpc: Add support for using doorbells for SMP IPI
Kumar Gala
galak at kernel.crashing.org
Tue Feb 24 03:23:40 EST 2009
On Feb 22, 2009, at 8:43 PM, Benjamin Herrenschmidt wrote:
> On Thu, 2009-02-12 at 17:54 -0600, Kumar Gala wrote:
>> 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.
>
> Any reason why you don't use the tag ? I'm not too familiar with the
> doorbell stuff just yet but can't you use that instead of doing those
> atomics ?
tag just conveys the type of doorbell (normal, critical, etc.). So
for the 4 IPI msgs we support we need software to keep track.
> On thing we also need to look at is change our low level msg send to
> take a CPU mask.
>
> This will be better generically and we need a good cpu mask based IPI
> for the TLB stuff anyway. Volunteer ? :-)
yeah.. It something on the list :)
- k
>> Signed-off-by: Kumar Gala <galak at kernel.crashing.org>
>> ---
>> arch/powerpc/include/asm/cputable.h | 4 ++-
>> arch/powerpc/include/asm/dbell.h | 43 ++++++++++++++++++++++++
>> +++++++++
>> arch/powerpc/kernel/Makefile | 2 +-
>> arch/powerpc/kernel/dbell.c | 44 ++++++++++++++++++++++++
>> ++++++++++
>> arch/powerpc/kernel/head_fsl_booke.S | 6 ++++-
>> arch/powerpc/kernel/traps.c | 21 ++++++++++++++++
>> 6 files changed, 117 insertions(+), 3 deletions(-)
>> create mode 100644 arch/powerpc/include/asm/dbell.h
>> create mode 100644 arch/powerpc/kernel/dbell.c
>>
>> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/
>> include/asm/cputable.h
>> index 4911104..fca1611 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 0000000..501189a
>> --- /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 d159921..f420844 100644
>> --- a/arch/powerpc/kernel/Makefile
>> +++ b/arch/powerpc/kernel/Makefile
>> @@ -61,7 +61,7 @@ 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 0000000..1493734
>> --- /dev/null
>> +++ b/arch/powerpc/kernel/dbell.c
>> @@ -0,0 +1,44 @@
>> +/*
>> + * Author: Kumar Gala <galak at 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 4ea6e1a..4c22620 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 at l
>> mtspr SPRN_IVOR36,r3
>> + li r3,CriticalDoorbell at l
>> + mtspr SPRN_IVOR37,r3
>> sync
>> blr
>>
>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/
>> traps.c
>> index 970d66e..678fbff 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)
>> {
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