diff options
Diffstat (limited to 'arch/arc/kernel/mcip.c')
| -rw-r--r-- | arch/arc/kernel/mcip.c | 55 |
1 files changed, 19 insertions, 36 deletions
diff --git a/arch/arc/kernel/mcip.c b/arch/arc/kernel/mcip.c index 30d806ce0..c41c364b9 100644 --- a/arch/arc/kernel/mcip.c +++ b/arch/arc/kernel/mcip.c @@ -15,6 +15,7 @@ #include <asm/mcip.h> #include <asm/setup.h> +#define IPI_IRQ 19 #define SOFTIRQ_IRQ 21 static char smp_cpuinfo_buf[128]; @@ -39,39 +40,26 @@ static void mcip_ipi_send(int cpu) return; } + raw_spin_lock_irqsave(&mcip_lock, flags); + /* - * NOTE: We must spin here if the other cpu hasn't yet - * serviced a previous message. This can burn lots - * of time, but we MUST follows this protocol or - * ipi messages can be lost!!! - * Also, we must release the lock in this loop because - * the other side may get to this same loop and not - * be able to ack -- thus causing deadlock. + * If receiver already has a pending interrupt, elide sending this one. + * Linux cross core calling works well with concurrent IPIs + * coalesced into one + * see arch/arc/kernel/smp.c: ipi_send_msg_one() */ + __mcip_cmd(CMD_INTRPT_READ_STATUS, cpu); + ipi_was_pending = read_aux_reg(ARC_REG_MCIP_READBACK); + if (!ipi_was_pending) + __mcip_cmd(CMD_INTRPT_GENERATE_IRQ, cpu); - do { - raw_spin_lock_irqsave(&mcip_lock, flags); - __mcip_cmd(CMD_INTRPT_READ_STATUS, cpu); - ipi_was_pending = read_aux_reg(ARC_REG_MCIP_READBACK); - if (ipi_was_pending == 0) - break; /* break out but keep lock */ - raw_spin_unlock_irqrestore(&mcip_lock, flags); - } while (1); - - __mcip_cmd(CMD_INTRPT_GENERATE_IRQ, cpu); raw_spin_unlock_irqrestore(&mcip_lock, flags); - -#ifdef CONFIG_ARC_IPI_DBG - if (ipi_was_pending) - pr_info("IPI ACK delayed from cpu %d\n", cpu); -#endif } static void mcip_ipi_clear(int irq) { unsigned int cpu, c; unsigned long flags; - unsigned int __maybe_unused copy; if (unlikely(irq == SOFTIRQ_IRQ)) { arc_softirq_clear(irq); @@ -83,7 +71,7 @@ static void mcip_ipi_clear(int irq) /* Who sent the IPI */ __mcip_cmd(CMD_INTRPT_CHECK_SOURCE, 0); - copy = cpu = read_aux_reg(ARC_REG_MCIP_READBACK); /* 1,2,4,8... */ + cpu = read_aux_reg(ARC_REG_MCIP_READBACK); /* 1,2,4,8... */ /* * In rare case, multiple concurrent IPIs sent to same target can @@ -97,12 +85,6 @@ static void mcip_ipi_clear(int irq) } while (cpu); raw_spin_unlock_irqrestore(&mcip_lock, flags); - -#ifdef CONFIG_ARC_IPI_DBG - if (c != __ffs(copy)) - pr_info("IPIs from %x coalesced to %x\n", - copy, raw_smp_processor_id()); -#endif } static void mcip_probe_n_setup(void) @@ -111,13 +93,13 @@ static void mcip_probe_n_setup(void) #ifdef CONFIG_CPU_BIG_ENDIAN unsigned int pad3:8, idu:1, llm:1, num_cores:6, - iocoh:1, grtc:1, dbg:1, pad2:1, + iocoh:1, gfrc:1, dbg:1, pad2:1, msg:1, sem:1, ipi:1, pad:1, ver:8; #else unsigned int ver:8, pad:1, ipi:1, sem:1, msg:1, - pad2:1, dbg:1, grtc:1, iocoh:1, + pad2:1, dbg:1, gfrc:1, iocoh:1, num_cores:6, llm:1, idu:1, pad3:8; #endif @@ -126,12 +108,13 @@ static void mcip_probe_n_setup(void) READ_BCR(ARC_REG_MCIP_BCR, mp); sprintf(smp_cpuinfo_buf, - "Extn [SMP]\t: ARConnect (v%d): %d cores with %s%s%s%s\n", + "Extn [SMP]\t: ARConnect (v%d): %d cores with %s%s%s%s%s\n", mp.ver, mp.num_cores, IS_AVAIL1(mp.ipi, "IPI "), IS_AVAIL1(mp.idu, "IDU "), + IS_AVAIL1(mp.llm, "LLM "), IS_AVAIL1(mp.dbg, "DEBUG "), - IS_AVAIL1(mp.grtc, "GRTC")); + IS_AVAIL1(mp.gfrc, "GFRC")); idu_detected = mp.idu; @@ -140,8 +123,8 @@ static void mcip_probe_n_setup(void) __mcip_cmd_data(CMD_DEBUG_SET_MASK, 0xf, 0xf); } - if (IS_ENABLED(CONFIG_ARC_HAS_GRTC) && !mp.grtc) - panic("kernel trying to use non-existent GRTC\n"); + if (IS_ENABLED(CONFIG_ARC_HAS_GFRC) && !mp.gfrc) + panic("kernel trying to use non-existent GFRC\n"); } struct plat_smp_ops plat_smp_ops = { |