On Fri, 15 Jan 2016, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>
> ACPI 6.0 introduces a new table STAO to list the devices which are used
> by Xen and can't be used by Dom0. On Xen virtual platforms, the physical
> UART is used by Xen. So here it hides UART from Dom0.
>
> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> ---
> CC: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> (supporter:ACPI)
> CC: Len Brown <lenb@xxxxxxxxxx> (supporter:ACPI)
> CC: linux-acpi@xxxxxxxxxxxxxxx (open list:ACPI)
> ---
> drivers/acpi/bus.c | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index a212cef..d7a559f 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 spcr_uart_addr;
>
> #ifdef CONFIG_X86
> #ifdef CONFIG_ACPI_CUSTOM_DSDT
> @@ -93,6 +94,17 @@ acpi_status acpi_bus_get_status_handle(acpi_handle handle,
> {
> acpi_status status;
>
> + if (spcr_uart_addr != 0xffffffffffffffff) {
Please #define something like EFI_INVALID_TABLE_ADDR and use it here
instead of 0xffffffffffffffff for readability. Also spcr_uart_addr could
be initialized where it is defined.
Maybe it could be better to move this check into a separate function and
only call acpi_set_device_status if spcr_uart_addr != addr?
> + u64 addr;
> +
> + status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL,
> + &addr);
> + if (ACPI_SUCCESS(status) && (addr == spcr_uart_addr)) {
> + *sta = 0;
> + return AE_OK;
> + }
> + }
> +
> status = acpi_evaluate_integer(handle, "_STA", NULL, sta);
> if (ACPI_SUCCESS(status))
> return AE_OK;
> @@ -1069,6 +1081,8 @@ EXPORT_SYMBOL_GPL(acpi_kobj);
> static int __init acpi_init(void)
> {
> int result;
> + acpi_status status;
> + struct acpi_table_stao *stao_ptr;
>
> if (acpi_disabled) {
> printk(KERN_INFO PREFIX "Interpreter disabled.\n");
> @@ -1081,6 +1095,22 @@ static int __init acpi_init(void)
> acpi_kobj = NULL;
> }
>
> + /* If there is STAO table, check whether it needs to ignore the UART
> + * device in SPCR table.
> + */
> + spcr_uart_addr = 0xffffffffffffffff;
> + status = acpi_get_table(ACPI_SIG_STAO, 0,
> + (struct acpi_table_header **)&stao_ptr);
> + if (ACPI_SUCCESS(status)) {
> + if (stao_ptr->ignore_uart) {
if (ACPI_SUCCESS(status) && stao_ptr->ignore_uart) {
> + struct acpi_table_spcr *spcr_ptr;
> +
> + acpi_get_table(ACPI_SIG_SPCR, 0,
> + (struct acpi_table_header **)&spcr_ptr);
Maybe we should check that acpi_get_table succeeded, even though it
should at this point.
> + spcr_uart_addr = spcr_ptr->serial_port.address;
> + }
> + }
> +
> init_acpi_device_notify();
> result = acpi_bus_init();
> if (result) {
--
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