ARM: virt: Don't generate RTC ACPI device when using UEFI

When booting the VM with UEFI, UEFI takes ownership of the RTC hardware.
While UEFI can use libfdt to disable the RTC device node in the DTB that
it passes to the OS, it cannot modify AML. Therefore, we won't generate
the RTC ACPI device at all when using UEFI.

Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Message-id: 1452867091-4023-1-git-send-email-shannon.zhao@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 0caf5ce..0d5c635 100644 (file)
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -94,23 +94,6 @@ static void acpi_dsdt_add_uart(Aml *scope, const MemMapEntry *uart_memmap,
     aml_append(scope, dev);
 }
 
-static void acpi_dsdt_add_rtc(Aml *scope, const MemMapEntry *rtc_memmap,
-                                          uint32_t rtc_irq)
-{
-    Aml *dev = aml_device("RTC0");
-    aml_append(dev, aml_name_decl("_HID", aml_string("LNRO0013")));
-    aml_append(dev, aml_name_decl("_UID", aml_int(0)));
-
-    Aml *crs = aml_resource_template();
-    aml_append(crs, aml_memory32_fixed(rtc_memmap->base,
-                                       rtc_memmap->size, AML_READ_WRITE));
-    aml_append(crs,
-               aml_interrupt(AML_CONSUMER, AML_LEVEL, AML_ACTIVE_HIGH,
-                             AML_EXCLUSIVE, &rtc_irq, 1));
-    aml_append(dev, aml_name_decl("_CRS", crs));
-    aml_append(scope, dev);
-}
-
 static void acpi_dsdt_add_flash(Aml *scope, const MemMapEntry *flash_memmap)
 {
     Aml *dev, *crs;
@@ -571,12 +554,15 @@ build_dsdt(GArray *table_data, GArray *linker, VirtGuestInfo *guest_info)
     /* Reserve space for header */
     acpi_data_push(dsdt->buf, sizeof(AcpiTableHeader));
 
+    /* When booting the VM with UEFI, UEFI takes ownership of the RTC hardware.
+     * While UEFI can use libfdt to disable the RTC device node in the DTB that
+     * it passes to the OS, it cannot modify AML. Therefore, we won't generate
+     * the RTC ACPI device at all when using UEFI.
+     */
     scope = aml_scope("\\_SB");
     acpi_dsdt_add_cpus(scope, guest_info->smp_cpus);
     acpi_dsdt_add_uart(scope, &memmap[VIRT_UART],
                        (irqmap[VIRT_UART] + ARM_SPI_BASE));
-    acpi_dsdt_add_rtc(scope, &memmap[VIRT_RTC],
-                      (irqmap[VIRT_RTC] + ARM_SPI_BASE));
     acpi_dsdt_add_flash(scope, &memmap[VIRT_FLASH]);
     acpi_dsdt_add_virtio(scope, &memmap[VIRT_MMIO],
                     (irqmap[VIRT_MMIO] + ARM_SPI_BASE), NUM_VIRTIO_TRANSPORTS);