From b9f1cd71dbf21a91fb7e2336a1d1ff18b97771e5 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Fri, 9 Jul 2010 15:29:53 +1000 Subject: powerpc/book3e: More doorbell cleanups. Sample the PIR register The doorbells use the content of the PIR register to match messages from other CPUs. This may or may not be the same as our linux CPU number, so using that as the "target" is no right. Instead, we sample the PIR register at boot on every processor and use that value subsequently when sending IPIs. We also use a per-cpu message mask rather than a global array which should limit cache line contention. Note: We could use the CPU number in the device-tree instead of the PIR register, as they are supposed to be equivalent. This might prove useful if doorbells are to be used to kick CPUs out of FW at boot time, thus before we can sample the PIR. This is however not the case now and using the PIR just works. Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/dbell.h | 7 +++--- arch/powerpc/kernel/dbell.c | 47 ++++++++++++++++++++++++++++----------- arch/powerpc/platforms/85xx/smp.c | 4 +++- 3 files changed, 40 insertions(+), 18 deletions(-) diff --git a/arch/powerpc/include/asm/dbell.h b/arch/powerpc/include/asm/dbell.h index 501189a543d1..ced7e487ca27 100644 --- a/arch/powerpc/include/asm/dbell.h +++ b/arch/powerpc/include/asm/dbell.h @@ -27,10 +27,9 @@ enum ppc_dbell { 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 +extern void doorbell_message_pass(int target, int msg); +extern void doorbell_exception(struct pt_regs *regs); +extern void doorbell_setup_this_cpu(void); static inline void ppc_msgsnd(enum ppc_dbell type, u32 flags, u32 tag) { diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/dbell.c index e3a717704fd6..1c7a94580c3f 100644 --- a/arch/powerpc/kernel/dbell.c +++ b/arch/powerpc/kernel/dbell.c @@ -13,45 +13,66 @@ #include #include #include +#include #include #ifdef CONFIG_SMP -unsigned long dbell_smp_message[NR_CPUS]; +struct doorbell_cpu_info { + unsigned long messages; /* current messages bits */ + unsigned int tag; /* tag value */ +}; -void smp_dbell_message_pass(int target, int msg) +static DEFINE_PER_CPU(struct doorbell_cpu_info, doorbell_cpu_info); + +void doorbell_setup_this_cpu(void) +{ + struct doorbell_cpu_info *info = &__get_cpu_var(doorbell_cpu_info); + + info->messages = 0; + info->tag = mfspr(SPRN_PIR) & 0x3fff; +} + +void doorbell_message_pass(int target, int msg) { + struct doorbell_cpu_info *info; int i; - if(target < NR_CPUS) { - set_bit(msg, &dbell_smp_message[target]); - ppc_msgsnd(PPC_DBELL, 0, target); + if (target < NR_CPUS) { + info = &per_cpu(doorbell_cpu_info, target); + set_bit(msg, &info->messages); + ppc_msgsnd(PPC_DBELL, 0, info->tag); } - else if(target == MSG_ALL_BUT_SELF) { + 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); + info = &per_cpu(doorbell_cpu_info, i); + set_bit(msg, &info->messages); + ppc_msgsnd(PPC_DBELL, 0, info->tag); } } else { /* target == MSG_ALL */ - for_each_online_cpu(i) - set_bit(msg, &dbell_smp_message[i]); + for_each_online_cpu(i) { + info = &per_cpu(doorbell_cpu_info, i); + set_bit(msg, &info->messages); + } ppc_msgsnd(PPC_DBELL, PPC_DBELL_MSG_BRDCAST, 0); } } void doorbell_exception(struct pt_regs *regs) { - int cpu = smp_processor_id(); + struct doorbell_cpu_info *info = &__get_cpu_var(doorbell_cpu_info); int msg; - if (num_online_cpus() < 2) + /* Warning: regs can be NULL when called from irq enable */ + + if (!info->messages || (num_online_cpus() < 2)) return; for (msg = 0; msg < 4; msg++) - if (test_and_clear_bit(msg, &dbell_smp_message[cpu])) + if (test_and_clear_bit(msg, &info->messages)) smp_message_recv(msg); } diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c index a15f582300d8..4c3cde911c71 100644 --- a/arch/powerpc/platforms/85xx/smp.c +++ b/arch/powerpc/platforms/85xx/smp.c @@ -99,6 +99,8 @@ static void __init smp_85xx_setup_cpu(int cpu_nr) { mpic_setup_this_cpu(); + if (cpu_has_feature(CPU_FTR_DBELL)) + doorbell_setup_this_cpu(); } struct smp_ops_t smp_85xx_ops = { @@ -117,7 +119,7 @@ void __init mpc85xx_smp_init(void) } if (cpu_has_feature(CPU_FTR_DBELL)) - smp_85xx_ops.message_pass = smp_dbell_message_pass; + smp_85xx_ops.message_pass = doorbell_message_pass; BUG_ON(!smp_85xx_ops.message_pass); -- cgit v1.2.3