summaryrefslogtreecommitdiffstats
path: root/arch/arc/kernel/mcip.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arc/kernel/mcip.c')
-rw-r--r--arch/arc/kernel/mcip.c60
1 files changed, 29 insertions, 31 deletions
diff --git a/arch/arc/kernel/mcip.c b/arch/arc/kernel/mcip.c
index bc771f5..c41c364 100644
--- a/arch/arc/kernel/mcip.c
+++ b/arch/arc/kernel/mcip.c
@@ -11,9 +11,13 @@
#include <linux/smp.h>
#include <linux/irq.h>
#include <linux/spinlock.h>
+#include <asm/irqflags-arcv2.h>
#include <asm/mcip.h>
#include <asm/setup.h>
+#define IPI_IRQ 19
+#define SOFTIRQ_IRQ 21
+
static char smp_cpuinfo_buf[128];
static int idu_detected;
@@ -22,6 +26,7 @@ static DEFINE_RAW_SPINLOCK(mcip_lock);
static void mcip_setup_per_cpu(int cpu)
{
smp_ipi_irq_setup(cpu, IPI_IRQ);
+ smp_ipi_irq_setup(cpu, SOFTIRQ_IRQ);
}
static void mcip_ipi_send(int cpu)
@@ -29,46 +34,44 @@ static void mcip_ipi_send(int cpu)
unsigned long flags;
int ipi_was_pending;
+ /* ARConnect can only send IPI to others */
+ if (unlikely(cpu == raw_smp_processor_id())) {
+ arc_softirq_trigger(SOFTIRQ_IRQ);
+ 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);
+ return;
+ }
raw_spin_lock_irqsave(&mcip_lock, flags);
/* 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
@@ -82,12 +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)
@@ -111,10 +108,11 @@ 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.gfrc, "GFRC"));
OpenPOWER on IntegriCloud