From 2c10c1dc2befc3d82d74507cc767e58cf11db173 Mon Sep 17 00:00:00 2001
From: Patrick Williams <iawillia@us.ibm.com>
Date: Thu, 3 Jun 2010 18:45:38 -0500
Subject: Add stub for decrementer interrupt.

---
 src/kernel/cpumgr.C  |  5 +++++
 src/kernel/start.S   | 30 ++++++++++++++++++++++++++----
 src/kernel/syscall.C | 10 ++++++++++
 src/kernel/taskmgr.C |  1 -
 4 files changed, 41 insertions(+), 5 deletions(-)

(limited to 'src')

diff --git a/src/kernel/cpumgr.C b/src/kernel/cpumgr.C
index f20139dd1..6855bfc1e 100644
--- a/src/kernel/cpumgr.C
+++ b/src/kernel/cpumgr.C
@@ -61,6 +61,11 @@ void CpuManager::startCPU(ssize_t i)
     {
 	register task_t* idle_task = iv_cpus[i]->scheduler->getIdleTask();
 	asm volatile("mtsprg3 %0" :: "r" (idle_task));
+
+	// TODO: Set up decrementer properly.
+	register uint64_t decrementer = 0x0f000000;
+	asm volatile("mtdec %0" :: "r"(decrementer));
+
     }
     else
     {
diff --git a/src/kernel/start.S b/src/kernel/start.S
index 8cb885c39..192b38685 100644
--- a/src/kernel/start.S
+++ b/src/kernel/start.S
@@ -105,11 +105,33 @@ intvect_fp_unavail:
 
 .org _start + 0x900
 intvect_decrementer:
-    b intvect_decrementer;
+    mtsprg1 r1 	;// Save GPR1
+	
+	;// Retrieve processing address for interrupt.
+    lis r1,intvect_decrementer_finish_save@h
+    ori r1,r1,intvect_decrementer_finish_save@l
+	;// Save interrupt address in SPRG0
+    mtsprg0 r1
+    
+    mfsprg1 r1 			;// Restore GPR1
+    b kernel_save_task 		;// Save current task.
+
+intvect_decrementer_finish_save:
+	;// Get TOC entry for kernel_execute_systemcall
+    lis r2, kernel_execute_decrementer@h
+    ori r2, r2, kernel_execute_decrementer@l
+    ld r0,0(r2)	;// Load call addr.
+    mtlr r0
+    ld r2,8(r2)	;// Load TOC base.
+
+    blrl			;// Call kernel_execute_systemcall
+    nop
+    b kernel_dispatch_task	;// Return to task.
+
 
 .org _start + 0x980
 intvect_hype_decrementer:
-    b intvect_hype_decrementer;
+    b intvect_decrementer;
 
 .org _start + 0xC00
 intvect_system_call:
@@ -132,7 +154,7 @@ intvect_system_call_finish_save:
     mtlr r0
     ld r2,8(r2)	;// Load TOC base.
 
-    blr				;// Call kernel_execute_systemcall
+    blrl			;// Call kernel_execute_systemcall
     nop
     b kernel_dispatch_task	;// Return to task.
 
@@ -270,7 +292,7 @@ kernel_dispatch_task:
     mtxer r23		;// Restore XER
     
     mfmsr r2		;// Get current MSR
-			;// TODO: Modify MSR to user-space.
+    ori r2,r2, 0xC000	;// Enable MSR[EE,PR].
     mtsrr1 r2		;// Set task MSR (SRR1)
 
     ld r2, TASK_NIP(r1)	;// Load NIP from context.
diff --git a/src/kernel/syscall.C b/src/kernel/syscall.C
index 250c18ae2..d59ea1a03 100644
--- a/src/kernel/syscall.C
+++ b/src/kernel/syscall.C
@@ -1,5 +1,15 @@
 #include <kernel/console.H>
 
+extern "C"
+void kernel_execute_decrementer()
+{
+    //printk("Decrementer.\n");
+    
+    // Resync decrementer.
+    register uint64_t decrementer = 0x0f000000;
+    asm volatile("mtdec %0" :: "r"(decrementer));
+}
+
 extern "C"
 void kernel_execute_systemcall()
 {
diff --git a/src/kernel/taskmgr.C b/src/kernel/taskmgr.C
index e5085655b..a3dcdf5f3 100644
--- a/src/kernel/taskmgr.C
+++ b/src/kernel/taskmgr.C
@@ -7,7 +7,6 @@ void TaskManager::idleTaskLoop()
 {
     while(1)
     {
-	asm volatile("sc");
     }
 }
 
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