[Xen-devel] [PATCH 01/13] Xen : Hide UART used by Xen

[shannon.zhao@xxxxxxxxxx]

From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>

According to the STAO table, hide UART used by Xen from Dom0.

Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
---
 drivers/acpi/bus.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index a212cef..e93806b 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -46,6 +46,7 @@ ACPI_MODULE_NAME("bus");
 struct acpi_device *acpi_root;
 struct proc_dir_entry *acpi_root_dir;
 EXPORT_SYMBOL(acpi_root_dir);
+static u64 uart_addr;
 
 #ifdef CONFIG_X86
 #ifdef CONFIG_ACPI_CUSTOM_DSDT
@@ -93,6 +94,16 @@ acpi_status acpi_bus_get_status_handle(acpi_handle handle,
 {
        acpi_status status;
 
+       if (uart_addr) {
+               u64 addr;
+               status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL,
+                                              &addr);
+               if (ACPI_SUCCESS(status) && (addr == uart_addr)) {
+                       *sta = 0;
+                       return AE_OK;
+               }
+       }
+
        status = acpi_evaluate_integer(handle, "_STA", NULL, sta);
        if (ACPI_SUCCESS(status))
                return AE_OK;
@@ -1069,6 +1080,7 @@ EXPORT_SYMBOL_GPL(acpi_kobj);
 static int __init acpi_init(void)
 {
        int result;
+       struct acpi_table_stao *stao_ptr;
 
        if (acpi_disabled) {
                printk(KERN_INFO PREFIX "Interpreter disabled.\n");
@@ -1081,6 +1093,16 @@ static int __init acpi_init(void)
                acpi_kobj = NULL;
        }
 
+       acpi_get_table(ACPI_SIG_STAO, 1,
+                      (struct acpi_table_header **)&stao_ptr);
+       if(stao_ptr->ignore_uart)
+       {
+               struct acpi_table_spcr *spcr_ptr;
+               acpi_get_table(ACPI_SIG_SPCR, 1,
+                              (struct acpi_table_header **)&spcr_ptr);
+               uart_addr = spcr_ptr->serial_port.address;
+       }
+
        init_acpi_device_notify();
        result = acpi_bus_init();
        if (result) {
-- 
2.1.0


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