From 779d4af3e995344742ec6a090c149ac9d6a48856 Mon Sep 17 00:00:00 2001
From: Stuart Ianna <stuart.ianna@motec.com.au>
Date: Thu, 12 Sep 2024 04:32:03 +0000
Subject: [PATCH] arch/risc-v/src/litex: Claim all pending PLIC interrupts.

Attempt to service all interrupts pending in the PLIC's claim register. Ideally, this is more efficient than switching context for each interrupt received.
---
 arch/risc-v/src/litex/litex_irq_dispatch.c | 46 +++++++++-------------
 1 file changed, 18 insertions(+), 28 deletions(-)

diff --git a/arch/risc-v/src/litex/litex_irq_dispatch.c b/arch/risc-v/src/litex/litex_irq_dispatch.c
index 0f2d3d72b4..3fabb1a3d6 100644
--- a/arch/risc-v/src/litex/litex_irq_dispatch.c
+++ b/arch/risc-v/src/litex/litex_irq_dispatch.c
@@ -47,48 +47,38 @@
  * riscv_dispatch_irq
  ****************************************************************************/
 
+#ifdef CONFIG_LITEX_CORE_VEXRISCV_SMP
 void *riscv_dispatch_irq(uintptr_t vector, uintreg_t *regs)
 {
-#ifdef CONFIG_LITEX_CORE_VEXRISCV_SMP
   int irq = (vector & 0x3f);
+  DEBUGASSERT(irq <= RISCV_IRQ_EXT);
 
   if ((vector & RISCV_IRQ_BIT) != 0)
     {
        irq += RISCV_IRQ_ASYNC;
     }
 
-  /* Firstly, check if the irq is machine external interrupt */
-
-  if (irq == RISCV_IRQ_EXT)
+  if (irq < RISCV_IRQ_EXT)
     {
-      uint32_t ext = getreg32(LITEX_PLIC_CLAIM);
-
-      /* Add the value to nuttx irq which is offset to the ext */
-
-      irq = RISCV_IRQ_EXT + ext;
-    }
-
-  /* Acknowledge the interrupt */
-
-  riscv_ack_irq(irq);
-
-  /* EXT means no interrupt */
-
-  if (irq != RISCV_IRQ_EXT)
-    {
-      /* Deliver the IRQ */
-
       regs = riscv_doirq(irq, regs);
     }
-
-  if (irq > RISCV_IRQ_EXT)
+  else
     {
-      /* Then write PLIC_CLAIM to clear pending in PLIC */
-
-      putreg32(irq - RISCV_IRQ_EXT, LITEX_PLIC_CLAIM);
+      uint32_t ext = getreg32(LITEX_PLIC_CLAIM);
+      do
+        {
+          regs = riscv_doirq(RISCV_IRQ_EXT + ext, regs);
+          putreg32(ext, LITEX_PLIC_CLAIM);
+          ext = getreg32(LITEX_PLIC_CLAIM);
+        }
+      while (ext);
     }
 
-#else 
+  return regs;
+}
+#else
+void *riscv_dispatch_irq(uintptr_t vector, uintreg_t *regs)
+{
   int i;
   int irq = (vector >> RV_IRQ_MASK) | (vector & 0xf);
 
@@ -127,6 +117,6 @@ void *riscv_dispatch_irq(uintptr_t vector, uintreg_t *regs)
 
   regs = riscv_doirq(irq, regs);
 
-#endif /* CONFIG_LITEX_CORE_VEXRISCV_SMP */
   return regs;
 }
+#endif