Handle suspend in qemu.

index 66a5faa..dd9100a 100644
@@ -53,6 +53,8 @@ typedef struct PIIX4PMState {
     qemu_irq irq;
 } PIIX4PMState;
 
+#define RSM_STS (1 << 15)
+#define PWRBTN_STS (1 << 8)
 #define RTC_EN (1 << 10)
 #define PWRBTN_EN (1 << 8)
 #define GBL_EN (1 << 5)

@@ -151,6 +153,14 @@ static void pm_ioport_writew(void *opaque, uint32_t addr, uint32_t val)
                 case 0: /* soft power off */
                     qemu_system_shutdown_request();
                     break;
+                case 1:
+                    /* RSM_STS should be set on resume. Pretend that resume
+                       was caused by power button */
+                    s->pmsts |= (RSM_STS | PWRBTN_STS);
+                    qemu_system_reset_request();
+#if defined(TARGET_I386)
+                    cmos_set_s3_resume();
+#endif
                 default:
                     break;
                 }

@@ -471,6 +481,17 @@ static int pm_load(QEMUFile* f,void* opaque,int version_id)
     return 0;
 }
 
+static void piix4_reset(void *opaque)
+{
+	PIIX4PMState *s = opaque;
+	uint8_t *pci_conf = s->dev.config;
+
+	pci_conf[0x58] = 0;
+	pci_conf[0x59] = 0;
+	pci_conf[0x5a] = 0;
+	pci_conf[0x5b] = 0;
+}
+
 i2c_bus *piix4_pm_init(PCIBus *bus, int devfn, uint32_t smb_io_base,
                        qemu_irq sci_irq)
 {

@@ -527,6 +548,8 @@ i2c_bus *piix4_pm_init(PCIBus *bus, int devfn, uint32_t smb_io_base,
 
     s->smbus = i2c_init_bus();
     s->irq = sci_irq;
+    qemu_register_reset(piix4_reset, s);
+
     return s->smbus;
 }
 

index 20827f2..bcacf3a 100644
@@ -1136,6 +1136,14 @@ static void pc_init_isa(ram_addr_t ram_size, int vga_ram_size,
              initrd_filename, 0, cpu_model);
 }
 
+/* set CMOS shutdown status register (index 0xF) as S3_resume(0xFE)
+   BIOS will read it and start S3 resume at POST Entry */
+void cmos_set_s3_resume(void)
+{
+    if (rtc_state)
+        rtc_set_memory(rtc_state, 0xF, 0xFE);
+}
+
 QEMUMachine pc_machine = {
     .name = "pc",
     .desc = "Standard PC",

index 39b220f..b0b8970 100644
@@ -82,6 +82,7 @@ RTCState *rtc_init(int base, qemu_irq irq);
 RTCState *rtc_mm_init(target_phys_addr_t base, int it_shift, qemu_irq irq);
 void rtc_set_memory(RTCState *s, int addr, int val);
 void rtc_set_date(RTCState *s, const struct tm *tm);
+void cmos_set_s3_resume(void);
 
 /* pc.c */
 extern int fd_bootchk;