Add the acpi table to the loongson rtc hardware so that the virtual machine
kernel can use the loongson RTC-related drivers.

Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
---
Cc: Song Gao <gaosong@loongson.cn> 
Cc: Bibo Mao <maobibo@loongson.cn> 
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com> 
Cc: "Huacai Chen"<zltjiangshi@gmail.com>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com> 

 hw/loongarch/virt-acpi-build.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/hw/loongarch/virt-acpi-build.c b/hw/loongarch/virt-acpi-build.c
index 3e34bedcd6..42820001d7 100644
--- a/hw/loongarch/virt-acpi-build.c
+++ b/hw/loongarch/virt-acpi-build.c
@@ -460,6 +460,30 @@ static void acpi_dsdt_add_tpm(Aml *scope, LoongArchVirtMachineState *vms)
 }
 #endif
 
+static void acpi_dsdt_add_rtc(Aml *scope)
+{
+    Aml *dev = aml_device("RTC");
+
+    aml_append(dev, aml_name_decl("_HID", aml_string("LOON0001")));
+    aml_append(dev, aml_name_decl("_UID", aml_int(0)));
+
+    Aml *crs = aml_resource_template();
+    aml_append(crs,
+        aml_qword_memory(AML_POS_DECODE, AML_MIN_FIXED, AML_MAX_FIXED,
+                         AML_NON_CACHEABLE, AML_READ_WRITE,
+                         0, VIRT_RTC_REG_BASE,
+                         VIRT_RTC_REG_BASE + VIRT_RTC_LEN - 1,
+                         0, VIRT_RTC_LEN));
+    /*
+     * The virtual machine model does not support suspend and wake-up,
+     * and rtc is no longer the wake-up source. Therefore, the current
+     * rtc table no longer provides the rtc alarm interrupt number to
+     * avoid the software initializing alarm.
+     */
+    aml_append(dev, aml_name_decl("_CRS", crs));
+    aml_append(scope, dev);
+}
+
 /* build DSDT */
 static void
 build_dsdt(GArray *table_data, BIOSLinker *linker, MachineState *machine)
@@ -475,6 +499,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, MachineState *machine)
     for (i = 0; i < VIRT_UART_COUNT; i++) {
         build_uart_device_aml(dsdt, i);
     }
+    acpi_dsdt_add_rtc(dsdt);
     build_pci_device_aml(dsdt, lvms);
     build_la_ged_aml(dsdt, machine);
     build_flash_aml(dsdt, lvms);
-- 
2.39.1