[PATCH] powerpc: Add support for using doorbells for SMP IPI
Benjamin Herrenschmidt
benh at kernel.crashing.org
Mon Feb 23 13:43:51 EST 2009
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 ?
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 ? :-)
Cheers,
Ben.
> 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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