acpi: parallel: don't use _STA method

The _STA method dates back to the days where we had a static DSDT.  The
device is listed in the DSDT table unconditionally and the _STA method
checks a bit in the isa bridge pci config space to figure whenever a
given is isa device is present or not, then evaluates to 0x0f (present)
or 0x00 (absent).

These days the DSDT is generated by qemu anyway, so if a device is not
present we can simply drop it from the DSDT instead.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200515150421.25479-7-kraxel@redhat.com>

hw/i386/acpi-build.c

@@ -1173,39 +1173,26 @@ static Aml *build_mouse_device_aml(void)
     return dev;
 }
 
-static Aml *build_lpt_device_aml(void)
+static void build_lpt_device_aml(Aml *scope)
 {
     Aml *dev;
     Aml *crs;
-    Aml *method;
-    Aml *if_ctx;
-    Aml *else_ctx;
-    Aml *zero = aml_int(0);
-    Aml *is_present = aml_local(0);
+
+    if (!memory_region_present(get_system_io(), 0x0378)) {
+        return;
+    }
 
     dev = aml_device("LPT");
     aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0400")));
 
-    method = aml_method("_STA", 0, AML_NOTSERIALIZED);
-    aml_append(method, aml_store(aml_name("LPEN"), is_present));
-    if_ctx = aml_if(aml_equal(is_present, zero));
-    {
-        aml_append(if_ctx, aml_return(aml_int(0x00)));
-    }
-    aml_append(method, if_ctx);
-    else_ctx = aml_else();
-    {
-        aml_append(else_ctx, aml_return(aml_int(0x0f)));
-    }
-    aml_append(method, else_ctx);
-    aml_append(dev, method);
+    aml_append(dev, aml_name_decl("_STA", aml_int(0xf)));
 
     crs = aml_resource_template();
     aml_append(crs, aml_io(AML_DECODE16, 0x0378, 0x0378, 0x08, 0x08));
     aml_append(crs, aml_irq_no_flags(7));
     aml_append(dev, aml_name_decl("_CRS", crs));
 
-    return dev;
+    aml_append(scope, dev);
 }
 
 static void build_isa_devices_aml(Aml *table)
@@ -1221,7 +1208,7 @@ static void build_isa_devices_aml(Aml *table)
     if (fdc) {
         aml_append(scope, build_fdc_device_aml(fdc));
     }
-    aml_append(scope, build_lpt_device_aml());
+    build_lpt_device_aml(scope);
 
     if (ambiguous) {
         error_report("Multiple ISA busses, unable to define IPMI ACPI data");