From d78b60f868f40cefe3ac958800ac828f2eafc81c Mon Sep 17 00:00:00 2001
From: Steven Le Rouzic <steven.lerouzic@gmail.com>
Date: Tue, 4 Jun 2024 23:32:33 +0200
Subject: Supervisor trap & claim MSI

---
 kernel/start.c | 77 ++++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 53 insertions(+), 24 deletions(-)

(limited to 'kernel/start.c')

diff --git a/kernel/start.c b/kernel/start.c
index 859ae5d..ddd31c2 100644
--- a/kernel/start.c
+++ b/kernel/start.c
@@ -11,29 +11,56 @@ extern uint32_t _bss_start;
 extern uint32_t _bss_end;
 extern uint32_t _ram_end;
 
-void kstrap()
+#define UART_MSI 1
+
+extern uint32_t strap;
+
+void ktrap(uint32_t cause)
 {
-    uint32_t scause;
-    __asm__ volatile("csrr %0, scause" : "=r"(scause));
-    switch (scause)
+    if ((cause & 0x8000'0000) == 0)
+    {
+        switch (cause)
+        {
+            case 0:  panic("kstrap: Instruction address misaligned");
+            case 1:  panic("kstrap: Instruction access fault");
+            case 2:  panic("kstrap: Illegal instruction");
+            case 3:  panic("kstrap: Breakpoint");
+            case 4:  panic("kstrap: Load address misaligned");
+            case 5:  panic("kstrap: Load access fault");
+            case 6:  panic("kstrap: Store/AMO address misaligned");
+            case 7:  panic("kstrap: Store/AMO access fault");
+            case 8:  panic("kstrap: Environment call from U-mode");
+            case 9:  panic("kstrap: Environment call from S-mode");
+            case 12: panic("kstrap: Instruction page fault");
+            case 13: panic("kstrap: Load page fault");
+            case 14: panic("kstrap: Reserved");
+            case 15: panic("kstrap: Store/AMO page fault");
+            case 18: panic("kstrap: Software check");
+            case 19: panic("kstrap: Hardware error");
+            default: panic("kstrap: Unknown");
+        }
+    }
+    else
     {
-        case 0: panic("kstrap: Instruction address misaligned");
-        case 1: panic("kstrap: Instruction access fault");
-        case 2: panic("kstrap: Illegal instruction");
-        case 3: panic("kstrap: Breakpoint");
-        case 4: panic("kstrap: Load address misaligned");
-        case 5: panic("kstrap: Load access fault");
-        case 6: panic("kstrap: Store/AMO address misaligned");
-        case 7: panic("kstrap: Store/AMO access fault");
-        case 8: panic("kstrap: Environment call from U-mode");
-        case 9: panic("kstrap: Environment call from S-mode");
-        case 12: panic("kstrap: Instruction page fault");
-        case 13: panic("kstrap: Load page fault");
-        case 14: panic("kstrap: Reserved");
-        case 15: panic("kstrap: Store/AMO page fault");
-        case 18: panic("kstrap: Software check");
-        case 19: panic("kstrap: Hardware error");
-        default: panic("kstrap: Unknown");
+        cause = cause & 0x7fff'ffff;
+        if (cause == 9)
+        {
+            uint32_t msi = aplic_claim_msi_s();
+            switch (msi)
+            {
+                case UART_MSI:
+                {
+                    volatile char* UART_BASE = (volatile char*)0x1000'0000;
+                    *UART_BASE = *UART_BASE;
+                    break;
+                }
+                default: panic("Unknown MSI");
+            }
+        }
+        else
+        {
+            panic("Interrupt");
+        }
     }
 }
 
@@ -57,9 +84,8 @@ void kstart()
     
     kalloc_init();
     kvm_init();
-    aplic_init();
    
-    panic("kstart: end");
+    panic("kstart: end\n");
 }
 
 void kinit()
@@ -80,7 +106,10 @@ void kinit()
     w_sstatus(SSTATUS_SPIE | SSTATUS_SPP_S);
     w_sie(SIE_SEIE);
     w_sepc(&kstart);
-    w_stvec(&kstrap);
+    w_stvec(&strap);
+    
+    aplic_init();
+    aplic_enable_intr_s(10, UART_MSI);
 
     w_pmpcfg0(PMPCFG_RW | PMPCFG_X | PMPCFG_TOR);
     w_pmpaddr0(((uint32_t)&_ram_end) >> PMPADDR_SHIFT);
-- 
cgit