x86/pic: new pic_setup_disabled function

This function is meant to initialize the legacy PIC in a disabled state,
for use in APIC systems where legacy hardware is still present.

2 files changed, 28 insertions, 4 deletions

diff --git a/arch/x86/machine/pic.c b/arch/x86/machine/pic.c
index 52f9461a..ab30ac20 100644
--- a/arch/x86/machine/pic.c
+++ b/arch/x86/machine/pic.c
@@ -16,6 +16,7 @@
  */
 
 #include <assert.h>
+#include <stdbool.h>
 #include <stdint.h>
 
 #include <kern/error.h>
@@ -198,8 +199,8 @@ pic_spurious_intr(void *arg)
     return 0;
 }
 
-void __init
-pic_setup(void)
+static void __init
+pic_setup_common(bool register_ctl)
 {
     int error;
 
@@ -227,7 +228,7 @@ pic_setup(void)
     io_write_byte(PIC_MASTER_IMR, pic_master_mask);
     io_write_byte(PIC_SLAVE_IMR, pic_slave_mask);
 
-    if (lapic_unused()) {
+    if (register_ctl) {
         pic_register();
     }
 
@@ -241,3 +242,15 @@ pic_setup(void)
                           &pic_slave_spurious_intr);
     error_check(error, __func__);
 }
+
+void __init
+pic_setup(void)
+{
+    pic_setup_common(true);
+}
+
+void __init
+pic_setup_disabled(void)
+{
+    pic_setup_common(false);
+}
diff --git a/arch/x86/machine/pic.h b/arch/x86/machine/pic.h
index 9da75b74..e49d336e 100644
--- a/arch/x86/machine/pic.h
+++ b/arch/x86/machine/pic.h
@@ -21,8 +21,19 @@
 #include <machine/trap.h>
 
 /*
- * Set up the pic module.
+ * Initialize the pic module.
  */
 void pic_setup(void);
 
+/*
+ * Initialize the pic module in an APIC system.
+ *
+ * This function is called by the acpi module if ACPI reports the presence
+ * of legacy interrupt controllers.
+ *
+ * Since it doesn't register the legacy PIC as an interrupt controller, the
+ * acpi module must have registered I/O APICs before calling this function.
+ */
+void pic_setup_disabled(void);
+
 #endif /* _X86_PIC_H */