Restructure interrupt/timer logic

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3362 42af7a65-404d-4744-a932-0658087f49c3

6 files changed, 383 insertions, 78 deletions

diff --git a/nuttx/arch/x86/include/i486/arch.h b/nuttx/arch/x86/include/i486/arch.h
index 5910f08a1..c5e4adad5 100755
--- a/nuttx/arch/x86/include/i486/arch.h
+++ b/nuttx/arch/x86/include/i486/arch.h
@@ -55,31 +55,249 @@
 
 /* FLAGS bits */
 
-#define X86_FLAGS_CF         (1 << 0)  /* Bit 0:  Carry Flag */
-                                       /* Bit 1:  Reserved */
-#define X86_FLAGS_PF         (1 << 2)  /* Bit 2:  Parity Flag */
-                                       /* Bit 3:  Reserved */
-#define X86_FLAGS_AF         (1 << 4)  /* Bit 4:  Auxillary carry Flag */
-                                       /* Bit 5:  Reserved */
-#define X86_FLAGS_ZF         (1 << 6)  /* Bit 6:  Zero Flag */
-#define X86_FLAGS_SF         (1 << 7)  /* Bit 7:  Sign Flag */
-#define X86_FLAGS_TF         (1 << 8)  /* Bit 8:  Trap Flag */
-#define X86_FLAGS_IF         (1 << 9)  /* Bit 9:  Interrupt Flag */
-#define X86_FLAGS_DF         (1 << 10) /* Bit 10: Direction Flag */
-#define X86_FLAGS_OF         (1 << 11) /* Bit 11: Overflow Flag */
-#define X86_FLAGS_IOPL_SHIFT (12)      /* Bits 12-13: IOPL mask (286+ only)*/
-#define X86_FLAGS_IOPL_MASK  (3 << X86_FLAGS_IOPL_SHIFT)
-#define X86_FLAGS_NT         (1 << 14) /* Bit 14: Nested Task */
-                                       /* Bit 15: Reserved */
+#define X86_FLAGS_CF             (1 << 0)  /* Bit 0:  Carry Flag */
+                                           /* Bit 1:  Reserved */
+#define X86_FLAGS_PF             (1 << 2)  /* Bit 2:  Parity Flag */
+                                           /* Bit 3:  Reserved */
+#define X86_FLAGS_AF             (1 << 4)  /* Bit 4:  Auxillary carry Flag */
+                                           /* Bit 5:  Reserved */
+#define X86_FLAGS_ZF             (1 << 6)  /* Bit 6:  Zero Flag */
+#define X86_FLAGS_SF             (1 << 7)  /* Bit 7:  Sign Flag */
+#define X86_FLAGS_TF             (1 << 8)  /* Bit 8:  Trap Flag */
+#define X86_FLAGS_IF             (1 << 9)  /* Bit 9:  Interrupt Flag */
+#define X86_FLAGS_DF             (1 << 10) /* Bit 10: Direction Flag */
+#define X86_FLAGS_OF             (1 << 11) /* Bit 11: Overflow Flag */
+#define X86_FLAGS_IOPL_SHIFT     (12)      /* Bits 12-13: IOPL mask (286+ only)*/
+#define X86_FLAGS_IOPL_MASK      (3 << X86_FLAGS_IOPL_SHIFT)
+#define X86_FLAGS_NT             (1 << 14) /* Bit 14: Nested Task */
+                                           /* Bit 15: Reserved */
 
 /* EFLAGS bits (Extend the basic FLAGS bit definitions) */
 
-#define X86_EFLAGS_RF        (1 << 16) /* Bit 16: Resume Flag (386+ only) */
-#define X86_EFLAGS_VM        (1 << 17) /* Bit 17: Virtual Mode (386+ only) */
-#define X86_EFLAGS_AC        (1 << 18) /* Bit 18: Alignment Check (486SX+ only) */
-#define X86_EFLAGS_VIF       (1 << 19) /* Bit 19: Virtual Interrupt Flag (Pentium+) */
-#define X86_EFLAGS_VIP       (1 << 20) /* Bit 20: Virtual Interrupt Pending (Pentium+) */
-#define X86_EFLAGS_ID        (1 << 21) /* Bit 21: CPUID detection flag (Pentium+) */
+#define X86_EFLAGS_RF            (1 << 16) /* Bit 16: Resume Flag (386+ only) */
+#define X86_EFLAGS_VM            (1 << 17) /* Bit 17: Virtual Mode (386+ only) */
+#define X86_EFLAGS_AC            (1 << 18) /* Bit 18: Alignment Check (486SX+ only) */
+#define X86_EFLAGS_VIF           (1 << 19) /* Bit 19: Virtual Interrupt Flag (Pentium+) */
+#define X86_EFLAGS_VIP           (1 << 20) /* Bit 20: Virtual Interrupt Pending (Pentium+) */
+#define X86_EFLAGS_ID            (1 << 21) /* Bit 21: CPUID detection flag (Pentium+) */
+
+/* Programmable Interrupt Controller (PIC) */
+
+/* Operational Control Words
+ *
+ * The first instruction the Operation Control Word 1 (OCW1) to set which
+ * IRQ's to mask and which IRQ's not to.
+ */
+
+#define PIC1_OCW1               0x20
+#define PIC2_OCW1               0xa0
+
+#  define PIC1_OCW1_IRQ0         (1 << 0) /* IRQ0  System Timer */
+#  define PIC1_OCW1_IRQ1         (1 << 1) /* IRQ1  Keyboard */
+#  define PIC1_OCW1_IRQ2         (1 << 2) /* IRQ2  PIC2 */
+#  define PIC1_OCW1_IRQ3         (1 << 3) /* IRQ3  Serial Port */
+#  define PIC1_OCW1_IRQ4         (1 << 4) /* IRQ4  Serial Port */
+#  define PIC1_OCW1_IRQ5         (1 << 5) /* IRQ5  Reserved/Sound Card */
+#  define PIC1_OCW1_IRQ6         (1 << 6) /* IRQ6  Floppy Disk Controller */
+#  define PIC1_OCW1_IRQ7         (1 << 7) /* IRQ7  Parallel Port */
+#  define PIC1_OCW1_ALL
+
+#  define PIC2_OCW1_IRQ8         (1 << 0) /* IRQ8  Real Time Clock */
+#  define PIC2_OCW1_IRQ9         (1 << 1) /* IRQ9  Redirected IRQ2 */
+#  define PIC2_OCW1_IRQ10        (1 << 2) /* IRQ10 Reserved */
+#  define PIC2_OCW1_IRQ11        (1 << 3) /* IRQ11 Reserved */
+#  define PIC2_OCW1_IRQ12        (1 << 4) /* IRQ12 PS/2 Mouse */
+#  define PIC2_OCW1_IRQ13        (1 << 5) /* IRQ13 Maths Co-Processor */
+#  define PIC2_OCW1_IRQ14        (1 << 6) /* IRQ14 Hard Disk Drive */
+#  define PIC2_OCW1_IRQ15        (1 << 7) /* IRQ15 Reserved */
+#  define PIC2_OCW1_ALL
+
+/* Operation Control Word 2 selects how the End of Interrupt (EOI) procedure
+ * works. The only thing of interest to us in this register is the non-
+ * specific EOI command, which we must send at the end of our ISR's.
+ */
+
+#define PIC1_OCW2                0x20
+#define PIC2_OCW2                0xa0
+
+#  define PIC_OCW2_ACT_SHIFT     (0)
+#  define PIC_OCW2_ACT_SHIFT     (7 << PIC_OCW2_ACT_SHIFT)
+#    define PIC1_OCW2_ACT_IRQ0   (0 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 0 */
+#    define PIC1_OCW2_ACT_IRQ1   (1 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 1 */
+#    define PIC1_OCW2_ACT_IRQ2   (2 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 2 */
+#    define PIC1_OCW2_ACT_IRQ3   (3 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 3 */
+#    define PIC1_OCW2_ACT_IRQ4   (4 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 4 */
+#    define PIC1_OCW2_ACT_IRQ5   (5 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 5 */
+#    define PIC1_OCW2_ACT_IRQ6   (6 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 6 */
+#    define PIC1_OCW2_ACT_IRQ7   (7 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 7 */
+
+#    define PIC2_OCW2_ACT_IRQ8   (0 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 8 */
+#    define PIC2_OCW2_ACT_IRQ9   (1 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 9 */
+#    define PIC2_OCW2_ACT_IRQ10  (2 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 10 */
+#    define PIC2_OCW2_ACT_IRQ11  (3 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 11 */
+#    define PIC2_OCW2_ACT_IRQ12  (4 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 12 */
+#    define PIC2_OCW2_ACT_IRQ13  (5 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 13 */
+#    define PIC2_OCW2_ACT_IRQ14  (6 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 14 */
+#    define PIC2_OCW2_ACT_IRQ15  (7 << PIC_OCW2_ACT_SHIFT) /* Act on IRQ 15 */
+
+#  define PIC_OCW2_EOI_SHIFT     (5)
+#  define PIC_OCW2_EOI_SHIFT     (7 << PIC_OCW2_EOI_SHIFT)
+#    define PIC_OCW2_EOI_AUTO    (0 << PIC_OCW2_EOI_SHIFT) /* Rotate in Auto EOI Mode (Clear) */
+#    define PIC_OCW2_EOI_NONSPEC (1 << PIC_OCW2_EOI_SHIFT) /* Non Specific EOI */
+#    define PIC_OCW2_EOI_SPEC    (3 << PIC_OCW2_EOI_SHIFT) /* Specific EOI */
+#    define PIC_OCW2_EOI_RAUTO   (4 << PIC_OCW2_EOI_SHIFT) /* Rotate in Auto EOI Mode (Set) */
+#    define PIC_OCW2_EOI_RNSPEC  (5 << PIC_OCW2_EOI_SHIFT) /* Rotate on Non-Specific EOI */
+#    define PIC_OCW2_EOI_PRIO    (6 << PIC_OCW2_EOI_SHIFT) /* Set Priority Command (Use Bits 2:0) */
+#    define PIC_OCW2_EOI_RSPEC   (7 << PIC_OCW2_EOI_SHIFT) /* Rotate on Specific EOI (Use Bits 2:0) */
+
+/* Operation Control Word 3.  Bits 0 and 1 bitsenable us to read the status
+ * of the Interrupt Request Register (IRR) and the In-Service Register (ISR).
+ * This is done by setting the appropriate bits correctly and reading the
+ * register at the Base Address.
+ *
+ * For example if we wanted to read the In-Service Register (ISR), then we
+ * would set both bits 1 and 0 to 1. The next read to the base register,
+ * (0x20 for PIC1 or 0xa0 for PIC2) will return the status of the In-Service
+ * Register. 
+ */
+
+#define PIC1_OCW3                0x20
+#define PIC2_OCW3                0xa0
+
+#  define PIC_OCW3_PCMD_SHIFT    (0)      /* Poll command */
+#  define PIC_OCW3_PCMD_MASK     (3 << PIC_OCW3_PCMD_SHIFT)
+#    define PIC_OCW3_PCMD_IRR    (2 << PIC_OCW3_PCMD_SHIFT) /* Next Read Returns Interrupt Request Register */
+#    define PIC_OCW3_PCMD_ISR    (3 << PIC_OCW3_PCMD_SHIFT) /* Next Read Returns In-Service Register */
+#  define PIC_OCW3_POLLCMD       (1 << 2) /* Poll command */
+#  define PIC_OCW3_ONE           (1 << 3) /* Must be set to 1 */
+#  define PIC_OCW3_SM_SHIFT      (5)
+#  define PIC_OCW3_SM_SHIFT      (3 << PIC_OCW3_SM_SHIFT)
+#    define PIC_OCW3_RSM         (2 << PIC_OCW3_SM_SHIFT) /* Reset Special Mask */
+#    define PIC_OCW3_SSM         (3 << PIC_OCW3_SM_SHIFT) /* Set Special Mask */
+
+/* If the PIC has been reset, it must be initialized with 2 to 4 Initialization
+ * Command Words (ICW) before it will accept and process Interrupt Requests. The
+ * following outlines the four possible Initialization Command Words. 
+ */
+
+#define PIC1_ICW1                0x20
+#define PIC2_ICW1                0xa0
+
+#  define PIC_ICW1_ICW4          (1 << 0) /* Will be Sending ICW4 (no ICW4) */
+#  define PIC_ICW1_SINGLE        (1 << 1) /* Single PIC (vs. Cascaded pics) */
+#  define PIC_ICW1_INTERVAL      (1 << 2) /* Call Address Interval of 4 (vs 8) */
+#  define PIC_ICW1_LEVEL         (1 << 3) /* Level Triggered Interrupts (vs Edge) */
+#  define PIC_ICW1_ICW1          (1 << 4) /* Must be set to 1 for ICW1 */
+#  define PIC_ICW1_VEC_SHIFT     (5)      /* Interrupt Vector Addresses for MCS-80/85 Mode */
+#  define PIC_ICW1_VEC_MASK      (7 << PIC_ICW1_VEC_SHIFT)
+
+/* Initialization Command Word 2 (ICW2) selects which vector information is
+ * released onto the bus, during the 2nd INTA Pulse. Using the 8086 mode,
+ * only bits 7:3 need to be used. This will be 00001000 (0x08) for PIC1 and
+ * 01110000 (0x70) for PIC2. If you wish to relocate the IRQ Vector Table,
+ * then you can use this register. 
+ */
+
+#define PIC1_ICW2                0x21
+#define PIC2_ICW2                0xa1
+
+/* There are two different Initialization Command Word 3's. One is used, if
+ * the PIC is a master, while the other is used for slaves.
+ */
+
+#define PIC1_ICW3                0x21
+#define PIC2_ICW3                0xa1
+
+/* Master ICW3 */
+
+#  define PIC1_ICW3_IRQ0         (1 << 0) /* IRQ0  is connected to a Slave */
+#  define PIC1_ICW3_IRQ1         (1 << 1) /* IRQ1  is connected to a Slave */
+#  define PIC1_ICW3_IRQ2         (1 << 2) /* IRQ2  is connected to a Slave */
+#  define PIC1_ICW3_IRQ3         (1 << 3) /* IRQ3  is connected to a Slave */
+#  define PIC1_ICW3_IRQ4         (1 << 4) /* IRQ4  is connected to a Slave */
+#  define PIC1_ICW3_IRQ5         (1 << 5) /* IRQ5  is connected to a Slave */
+#  define PIC1_ICW3_IRQ6         (1 << 6) /* IRQ6  is connected to a Slave */
+#  define PIC1_ICW3_IRQ7         (1 << 7) /* IRQ7  is connected to a Slave */
+
+/* And for the slave device, the ICW3 below is used. */
+
+#  define PIC_ICW3_SID_MASK      (0)      /* Slave ID */
+#  define PIC_ICW3_SID_SHIFT     (7 << PIC_ICW3_SID_MASK)
+#    define PIC_ICW3_SID0        (0 << PIC_ICW3_SID_MASK) /* Slave 0 */
+#    define PIC_ICW3_SID1        (1 << PIC_ICW3_SID_MASK) /* Slave 1 */
+#    define PIC_ICW3_SID2        (2 << PIC_ICW3_SID_MASK) /* Slave 2 */
+#    define PIC_ICW3_SID3        (3 << PIC_ICW3_SID_MASK) /* Slave 3 */
+#    define PIC_ICW3_SID4        (4 << PIC_ICW3_SID_MASK) /* Slave 4 */
+#    define PIC_ICW3_SID5        (5 << PIC_ICW3_SID_MASK) /* Slave 5 */
+#    define PIC_ICW3_SID6        (6 << PIC_ICW3_SID_MASK) /* Slave 6 */
+#    define PIC_ICW3_SID7        (7 << PIC_ICW3_SID_MASK) /* Slave 7 */
+
+#define PIC1_ICW4                0x21
+#define PIC2_ICW4                0xa1
+
+#  define PIC_ICW4_FNM           (1 << 4) /* Special Fully Nested Mode */
+#  define PIC_ICW4_BMODE_SHIFT   (2)      /* Bufferd mode */
+#  define PIC_ICW4_BMODE_MASK    (3 << PIC_ICW4_BMODE_SHIFT)
+#    define PIC_ICW4_BMODE_NON   (0 << PIC_ICW4_BMODE_SHIFT) /* Non - Buffered Mode */
+#    define PIC_ICW4_BMODE_SLAVE (2 << PIC_ICW4_BMODE_SHIFT) /* Buffered Mode - Slave */
+#    define PIC_ICW4_BMODE_MSTR  (3 << PIC_ICW4_BMODE_SHIFT) /* Buffered Mode - Master */
+#  define PIC_ICW4_AEOI          (1 << 1) /* Auto EOI  */
+#  define PIC_ICW4_808xMODE      (1 << 0) /* 8086/8080 Mode (vs MCS-80/85) */
+
+/* Interrupt Mask Register */
+
+#define PIC1_IMR                 0x21
+#define PIC2_IMR                 0xa1
+
+#  define PIC1_IMR_IRQ0         (1 << 0) /* IRQ0  System Timer */
+#  define PIC1_IMR_IRQ1         (1 << 1) /* IRQ1  Keyboard */
+#  define PIC1_IMR_IRQ2         (1 << 2) /* IRQ2  PIC2 */
+#  define PIC1_IMR_IRQ3         (1 << 3) /* IRQ3  Serial Port */
+#  define PIC1_IMR_IRQ4         (1 << 4) /* IRQ4  Serial Port */
+#  define PIC1_IMR_IRQ5         (1 << 5) /* IRQ5  Reserved/Sound Card */
+#  define PIC1_IMR_IRQ6         (1 << 6) /* IRQ6  Floppy Disk Controller */
+#  define PIC1_IMR_IRQ7         (1 << 7) /* IRQ7  Parallel Port */
+#  define PIC1_IMR_ALL          0xff
+
+#  define PIC2_IMR_IRQ8         (1 << 0) /* IRQ8  Real Time Clock */
+#  define PIC2_IMR_IRQ9         (1 << 1) /* IRQ9  Redirected IRQ2 */
+#  define PIC2_IMR_IRQ10        (1 << 2) /* IRQ10 Reserved */
+#  define PIC2_IMR_IRQ11        (1 << 3) /* IRQ11 Reserved */
+#  define PIC2_IMR_IRQ12        (1 << 4) /* IRQ12 PS/2 Mouse */
+#  define PIC2_IMR_IRQ13        (1 << 5) /* IRQ13 Maths Co-Processor */
+#  define PIC2_IMR_IRQ14        (1 << 6) /* IRQ14 Hard Disk Drive */
+#  define PIC2_IMR_IRQ15        (1 << 7) /* IRQ15 Reserved */
+#  define PIC2_IMR_ALL          0xff
+
+/* Programmable Interrupt Timer Definitions */
+
+#define PIT_REG_COUNTER0        0x40
+#define PIT_REG_COUNTER1        0x41
+#define PIT_REG_COUNTER2        0x42
+#define PIT_REG_COMMAND         0x43
+
+/* PIT command bit defintions */
+
+#  define PIT_OCW_BINCOUNT_BCD  (1 << 0) /* vs binary */
+#  define PIT_OCW_MODE_SHIFT    (1)
+#  define PIT_OCW_MODE_MASK     (7 << PIT_OCW_MODE_SHIFT)
+#    define PIT_OCW_MODE_TMCNT  (0 << PIT_OCW_MODE_SHIFT)  /* Terminal count */
+#    define PIT_OCW_MODE_ONESHOT (1 << PIT_OCW_MODE_SHIFT) /* One shot */
+#    define PIT_OCW_MODE_RATEGEN (2 << PIT_OCW_MODE_SHIFT) /* Rate gen */
+#    define PIT_OCW_MODE_SQUARE (3 << PIT_OCW_MODE_SHIFT)  /* Square wave generation */
+#    define PIT_OCW_MODE_SWTRIG (4 << PIT_OCW_MODE_SHIFT)  /* Software trigger */
+#    define PIT_OCW_MODE_HWTRIG (5 << PIT_OCW_MODE_SHIFT)  /* Hardware trigger */
+#  define PIT_OCW_RL_SHIFT      (4)
+#  define PIT_OCW_RL_MASK       (3 << PIT_OCW_RL_SHIFT)
+#    define PIT_OCW_RL_LATCH    (0 << PIT_OCW_RL_SHIFT)
+#    define PIT_OCW_RL_LSBONLY  (1 << PIT_OCW_RL_SHIFT)
+#    define PIT_OCW_RL_MSBONLY  (2 << PIT_OCW_RL_SHIFT)
+#    define PIT_OCW_RL_DATA     (3 << PIT_OCW_RL_SHIFT)
+#  define PIT_OCW_COUNTER_SHIFT (6)
+#  define PIT_OCW_COUNTER_MASK  (3 << PIT_OCW_COUNTER_SHIFT)
+#    define PIT_OCW_COUNTER_0   (0 << PIT_OCW_COUNTER_SHIFT)
+#    define PIT_OCW_COUNTER_1   (1 << PIT_OCW_COUNTER_SHIFT)
+#    define PIT_OCW_COUNTER_2   (2 << PIT_OCW_COUNTER_SHIFT)
 
 /****************************************************************************
  * Public Types
diff --git a/nuttx/arch/x86/src/qemu/qemu_irq.c b/nuttx/arch/x86/src/i486/up_irq.c
index b92db7882..33a9130d5 100755
--- a/nuttx/arch/x86/src/qemu/qemu_irq.c
+++ b/nuttx/arch/x86/src/i486/up_irq.c
@@ -1,6 +1,6 @@
 /****************************************************************************
- * arch/x86/src/qemu/qemu_irq.c
- * arch/x86/src/chip/qemu_irq.c
+ * arch/x86/src/i486/up_irq.c
+ * arch/x86/src/chip/up_irq.c
  *
  *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
@@ -113,27 +113,31 @@ static void up_remappic(void)
 {
   /* Mask interrupts from PIC */
 
-  idt_outb(0xff, 0x21);
-  idt_outb(0xff, 0xA1);
+  idt_outb(PIC1_IMR_ALL, PIC1_IMR);
+  idt_outb(PIC2_IMR_ALL, PIC2_IMR);
 
-  /* Remap the irq table for primary */
+  /* If the PIC has been reset, it must be initialized with 2 to 4 Initialization
+   * Command Words (ICW) before it will accept and process Interrupt Requests. The
+   * following outlines the four possible Initialization Command Words. 
+   */
 
-  idt_outb(0x11, 0x20);
-  idt_outb(0x20, 0x21);
-  idt_outb(0x04, 0x21);
-  idt_outb(0x01, 0x21);
-  
-  /* Remap irq for slave */
+  /* Remap the irq table for primary:
+   *
+   * ICW1 - We will be sending ICW4
+   * ICW2 - Address
+   * ICW3    */
 
-  idt_outb(0x11, 0xA0);
-  idt_outb(0x28, 0xA1);
-  idt_outb(0x02, 0xA1);
-  idt_outb(0x01, 0xA1);    
+  idt_outb(PIC_ICW1_ICW4|PIC_ICW1_ICW1, PIC1_ICW1);
+  idt_outb(0x20,                        PIC1_ICW2);
+  idt_outb(PIC1_ICW3_IRQ2,              PIC1_ICW3);
+  idt_outb(PIC_ICW4_808xMODE,           PIC1_ICW4);
 
-  /* Enable IRQ0 on the master with the mask */
+  /* Remap irq for slave */
 
-  idt_outb( 0xff, 0xA1);
-  idt_outb( 0xfe, 0x21);
+  idt_outb(PIC_ICW1_ICW4|PIC_ICW1_ICW1, PIC2_ICW1);
+  idt_outb(0x28,                        PIC2_ICW2);
+  idt_outb(PIC_ICW3_SID2,               PIC2_ICW3);
+  idt_outb(PIC_ICW4_808xMODE,           PIC2_ICW4);
 }
 
 /****************************************************************************
@@ -147,8 +151,8 @@ static void up_remappic(void)
 static void up_idtentry(struct idt_entry_s *entry, uint32_t base,
                         uint16_t sel, uint8_t flags)
 {
-  entry->lobase = base & 0xFFFF;
-  entry->hibase = (base >> 16) & 0xFFFF;
+  entry->lobase = base & 0xffff;
+  entry->hibase = (base >> 16) & 0xffff;
 
   entry->sel    = sel;
   entry->zero   = 0;
@@ -214,16 +218,16 @@ static inline void up_idtinit(void)
   up_idtentry(&idt_entries[29], (uint32_t)vector_isr29, 0x08, 0x8e);
   up_idtentry(&idt_entries[30], (uint32_t)vector_isr30, 0x08, 0x8e);
   up_idtentry(&idt_entries[31], (uint32_t)vector_isr31, 0x08, 0x8e);
-  up_idtentry(&idt_entries[32], (uint32_t)vector_irq0, 0x08, 0x8e);
-  up_idtentry(&idt_entries[33], (uint32_t)vector_irq1, 0x08, 0x8e);
-  up_idtentry(&idt_entries[34], (uint32_t)vector_irq2, 0x08, 0x8e);
-  up_idtentry(&idt_entries[35], (uint32_t)vector_irq3, 0x08, 0x8e);
-  up_idtentry(&idt_entries[36], (uint32_t)vector_irq4, 0x08, 0x8e);
-  up_idtentry(&idt_entries[37], (uint32_t)vector_irq5, 0x08, 0x8e);
-  up_idtentry(&idt_entries[38], (uint32_t)vector_irq6, 0x08, 0x8e);
-  up_idtentry(&idt_entries[39], (uint32_t)vector_irq7, 0x08, 0x8e);
-  up_idtentry(&idt_entries[40], (uint32_t)vector_irq8, 0x08, 0x8e);
-  up_idtentry(&idt_entries[41], (uint32_t)vector_irq9, 0x08, 0x8e);
+  up_idtentry(&idt_entries[32], (uint32_t)vector_irq0,  0x08, 0x8e);
+  up_idtentry(&idt_entries[33], (uint32_t)vector_irq1,  0x08, 0x8e);
+  up_idtentry(&idt_entries[34], (uint32_t)vector_irq2,  0x08, 0x8e);
+  up_idtentry(&idt_entries[35], (uint32_t)vector_irq3,  0x08, 0x8e);
+  up_idtentry(&idt_entries[36], (uint32_t)vector_irq4,  0x08, 0x8e);
+  up_idtentry(&idt_entries[37], (uint32_t)vector_irq5,  0x08, 0x8e);
+  up_idtentry(&idt_entries[38], (uint32_t)vector_irq6,  0x08, 0x8e);
+  up_idtentry(&idt_entries[39], (uint32_t)vector_irq7,  0x08, 0x8e);
+  up_idtentry(&idt_entries[40], (uint32_t)vector_irq8,  0x08, 0x8e);
+  up_idtentry(&idt_entries[41], (uint32_t)vector_irq9,  0x08, 0x8e);
   up_idtentry(&idt_entries[42], (uint32_t)vector_irq10, 0x08, 0x8e);
   up_idtentry(&idt_entries[43], (uint32_t)vector_irq11, 0x08, 0x8e);
   up_idtentry(&idt_entries[44], (uint32_t)vector_irq12, 0x08, 0x8e);
@@ -258,3 +262,98 @@ void up_irqinitialize(void)
   irqrestore(X86_FLAGS_IF);
 #endif
 }
+
+/****************************************************************************
+ * Name: up_disable_irq
+ *
+ * Description:
+ *   Disable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_disable_irq(int irq)
+{
+  unsigned int regaddr;
+  uint8_t      regbit;
+ 
+  if ((unsigned)irq >= IRQ0)
+    {
+      /* Map the IRQ IMR regiser to a PIC and a bit number */
+
+      if ((unsigned)irq <= IRQ7)
+        {
+          regaddr = PIC1_IMR;
+          regbit  = (1 << (irq - IRQ0));
+        }
+      else if ((unsigned)irq <= IRQ15)
+        {
+          regaddr = PIC2_IMR;
+          regbit  = (1 << (irq - IRQ8));
+        }
+      else
+        {
+          return;
+        }
+
+      /* Disable the interrupt */
+
+      modifyreg8(regaddr, regbit, 0);
+    }
+}
+
+/****************************************************************************
+ * Name: up_enable_irq
+ *
+ * Description:
+ *   Enable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_enable_irq(int irq)
+{
+  unsigned int regaddr;
+  uint8_t      regbit;
+ 
+  if ((unsigned)irq >= IRQ0)
+    {
+      /* Map the IRQ IMR regiser to a PIC and a bit number */
+
+      if ((unsigned)irq <= IRQ7)
+        {
+          regaddr = PIC1_IMR;
+          regbit  = (1 << (irq - IRQ0));
+        }
+      else if ((unsigned)irq <= IRQ15)
+        {
+          regaddr = PIC2_IMR;
+          regbit  = (1 << (irq - IRQ8));
+        }
+      else
+        {
+          return;
+        }
+
+      /* Enable the interrupt */
+
+      modifyreg8(regaddr, 0, regbit);
+    }
+}
+
+/****************************************************************************
+ * Name: up_prioritize_irq
+ *
+ * Description:
+ *   Set the priority of an IRQ.
+ *
+ *   Since this API is not supported on all architectures, it should be
+ *   avoided in common implementations where possible.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_IRQPRIO
+int up_prioritize_irq(int irq, int priority)
+{
+#warning "Missing Logic"
+  return OK;
+}
+#endif
diff --git a/nuttx/arch/x86/src/qemu/Make.defs b/nuttx/arch/x86/src/qemu/Make.defs
index 4c3a83380..3177f3db4 100755
--- a/nuttx/arch/x86/src/qemu/Make.defs
+++ b/nuttx/arch/x86/src/qemu/Make.defs
@@ -42,7 +42,7 @@ HEAD_ASRC	= qemu_head.S
 CMN_ASRCS	= i486_utils.S
 CMN_CSRCS	= up_allocateheap.c up_assert.c up_blocktask.c up_copystate.c \
 			  up_createstack.c up_mdelay.c up_udelay.c up_exit.c\
-			  up_initialize.c up_initialstate.c up_interruptcontext.c \
+			  up_initialize.c up_initialstate.c up_interruptcontext.c up_irq.c \
 			  up_modifyreg8.c up_modifyreg16.c up_modifyreg32.c up_regdump.c \
 			  up_releasepending.c up_releasestack.c up_reprioritizertr.c \
 			  up_sigdeliver.c up_schedulesigaction.c up_unblocktask.c \
@@ -51,7 +51,7 @@ CMN_CSRCS	= up_allocateheap.c up_assert.c up_blocktask.c up_copystate.c \
 # Required QEMU files
 
 CHIP_ASRCS	= qemu_saveusercontext.S qemu_fullcontextrestore.S qemu_vectors.S
-CHIP_CSRCS	= qemu_handlers.c qemu_idle.c qemu_irq.c qemu_lowputc.c \
-			  qemu_lowsetup.c qemu_serial.c qemu_timerisr.c
+CHIP_CSRCS	= qemu_handlers.c qemu_idle.c qemu_lowputc.c qemu_lowsetup.c \
+			  qemu_serial.c qemu_timerisr.c
 
 # Configuration-dependent QEMU files
diff --git a/nuttx/arch/x86/src/qemu/qemu_timerisr.c b/nuttx/arch/x86/src/qemu/qemu_timerisr.c
index ddc4a5e74..ca51816af 100755
--- a/nuttx/arch/x86/src/qemu/qemu_timerisr.c
+++ b/nuttx/arch/x86/src/qemu/qemu_timerisr.c
@@ -79,9 +79,6 @@
 
 #define PIT_DIVISOR  ((uint32_t)PIT_CLOCK/(uint32_t)CLK_TCK)
 
-#define PIT_MODE     0x43
-#define PIT_CH0      0x40
-
 /****************************************************************************
  * Private Types
  ****************************************************************************/
@@ -90,7 +87,7 @@
  * Private Function Prototypes
  ****************************************************************************/
 
-static void pit_outb(uint8_t val, uint16_t addr) __attribute__((noinline));
+static void outb(uint8_t val, uint16_t addr) __attribute__((noinline));
 static int up_timerisr(int irq, uint32_t *regs);
 
 /****************************************************************************
@@ -98,19 +95,6 @@ static int up_timerisr(int irq, uint32_t *regs);
  ****************************************************************************/
 
 /****************************************************************************
- * Name pit_outb
- *
- * Description:
- *   A slightly slower version of outb
- *
- ****************************************************************************/
-
-static void pit_outb(uint8_t val, uint16_t addr)
-{
-  outb(val, addr);
-}
-
-/****************************************************************************
  * Function:  up_timerisr
  *
  * Description:
@@ -151,12 +135,16 @@ void up_timerinit(void)
 
   (void)irq_attach(IRQ0, (xcpt_t)up_timerisr);
 
-  /* Send the command byte */
+  /* Send the command byte to configure counter 0 */
 
-  pit_outb(0x36, PIT_MODE);
+  outb(PIT_OCW_MODE_SQUARE|PIT_OCW_RL_DATA|PIT_OCW_COUNTER_0, PIT_REG_COMMAND);
 
   /* Set the PIT input frequency divisor */
 
-  pit_outb((uint8_t)(divisor & 0xff),  PIT_CH0);
-  pit_outb((uint8_t)((divisor >> 8) & 0xff), PIT_CH0);
+  outb((uint8_t)(divisor & 0xff),  PIT_REG_COUNTER0);
+  outb((uint8_t)((divisor >> 8) & 0xff), PIT_REG_COUNTER0);
+
+  /* And enable IRQ0 */
+
+  up_enable_irq(IRQ0);
 }
diff --git a/nuttx/configs/qemu-i486/nsh/defconfig b/nuttx/configs/qemu-i486/nsh/defconfig
index 8244e35bc..3cec37a3b 100644
--- a/nuttx/configs/qemu-i486/nsh/defconfig
+++ b/nuttx/configs/qemu-i486/nsh/defconfig
@@ -80,7 +80,7 @@ CONFIG_BOARD_LOOPSPERMSEC=999
 CONFIG_DRAM_SIZE=0x00100000
 CONFIG_DRAM_START=0x00100000
 CONFIG_DRAM_END=(CONFIG_DRAM_START+CONFIG_DRAM_SIZE)
-CONFIG_ARCH_NOINTC=y
+CONFIG_ARCH_NOINTC=n
 CONFIG_ARCH_STACKDUMP=y
 CONFIG_ARCH_LEDS=n
 CONFIG_ARCH_BUTTONS=n
diff --git a/nuttx/configs/qemu-i486/ostest/defconfig b/nuttx/configs/qemu-i486/ostest/defconfig
index 8b17c30b8..c84f50822 100644
--- a/nuttx/configs/qemu-i486/ostest/defconfig
+++ b/nuttx/configs/qemu-i486/ostest/defconfig
@@ -80,7 +80,7 @@ CONFIG_BOARD_LOOPSPERMSEC=999
 CONFIG_DRAM_SIZE=0x00100000
 CONFIG_DRAM_START=0x00100000
 CONFIG_DRAM_END=(CONFIG_DRAM_START+CONFIG_DRAM_SIZE)
-CONFIG_ARCH_NOINTC=y
+CONFIG_ARCH_NOINTC=n
 CONFIG_ARCH_STACKDUMP=y
 CONFIG_ARCH_LEDS=n
 CONFIG_ARCH_BUTTONS=n