On Mon, 18 Apr 2016, Rafael J. Wysocki wrote: > On Thu, Apr 7, 2016 at 2:03 PM, Shannon Zhao <zhaoshenglong@xxxxxxxxxx> 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. > > > > CC: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> (supporter:ACPI) > > CC: Len Brown <lenb@xxxxxxxxxx> (supporter:ACPI) > > CC: linux-acpi@xxxxxxxxxxxxxxx (open list:ACPI) > > Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx> > > Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> I am going to commit it to the xentip tree, if you prefer to take it in your tree please let me know. > > --- > > drivers/acpi/scan.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 74 insertions(+) > > > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > > index 5f28cf7..cfc73fe 100644 > > --- a/drivers/acpi/scan.c > > +++ b/drivers/acpi/scan.c > > @@ -46,6 +46,13 @@ DEFINE_MUTEX(acpi_device_lock); > > LIST_HEAD(acpi_wakeup_device_list); > > static DEFINE_MUTEX(acpi_hp_context_lock); > > > > +/* > > + * The UART device described by the SPCR table is the only object which needs > > + * special-casing. Everything else is covered by ACPI namespace paths in STAO > > + * table. > > + */ > > +static u64 spcr_uart_addr; > > + > > struct acpi_dep_data { > > struct list_head node; > > acpi_handle master; > > @@ -1453,6 +1460,41 @@ static int acpi_add_single_object(struct acpi_device **child, > > return 0; > > } > > > > +static acpi_status acpi_get_resource_memory(struct acpi_resource *ares, > > + void *context) > > +{ > > + struct resource *res = context; > > + > > + if (acpi_dev_resource_memory(ares, res)) > > + return AE_CTRL_TERMINATE; > > + > > + return AE_OK; > > +} > > + > > +static bool acpi_device_should_be_hidden(acpi_handle handle) > > +{ > > + acpi_status status; > > + struct resource res; > > + > > + /* Check if it should ignore the UART device */ > > + if (!(spcr_uart_addr && acpi_has_method(handle, METHOD_NAME__CRS))) > > + return false; > > + > > + /* > > + * The UART device described in SPCR table is assumed to have only one > > + * memory resource present. So we only look for the first one here. > > + */ > > + status = acpi_walk_resources(handle, METHOD_NAME__CRS, > > + acpi_get_resource_memory, &res); > > + if (ACPI_FAILURE(status) || res.start != spcr_uart_addr) > > + return false; > > + > > + acpi_handle_info(handle, "The UART device @%pa in SPCR table will be hidden\n", > > + &res.start); > > + > > + return true; > > +} > > + > > static int acpi_bus_type_and_status(acpi_handle handle, int *type, > > unsigned long long *sta) > > { > > @@ -1466,6 +1508,9 @@ static int acpi_bus_type_and_status(acpi_handle handle, int *type, > > switch (acpi_type) { > > case ACPI_TYPE_ANY: /* for ACPI_ROOT_OBJECT */ > > case ACPI_TYPE_DEVICE: > > + if (acpi_device_should_be_hidden(handle)) > > + return -ENODEV; > > + > > *type = ACPI_BUS_TYPE_DEVICE; > > status = acpi_bus_get_status_handle(handle, sta); > > if (ACPI_FAILURE(status)) > > @@ -1916,9 +1961,24 @@ static int acpi_bus_scan_fixed(void) > > return result < 0 ? result : 0; > > } > > > > +static void __init acpi_get_spcr_uart_addr(void) > > +{ > > + acpi_status status; > > + struct acpi_table_spcr *spcr_ptr; > > + > > + status = acpi_get_table(ACPI_SIG_SPCR, 0, > > + (struct acpi_table_header **)&spcr_ptr); > > + if (ACPI_SUCCESS(status)) > > + spcr_uart_addr = spcr_ptr->serial_port.address; > > + else > > + printk(KERN_WARNING PREFIX "STAO table present, but SPCR is missing\n"); > > +} > > + > > int __init acpi_scan_init(void) > > { > > int result; > > + acpi_status status; > > + struct acpi_table_stao *stao_ptr; > > > > acpi_pci_root_init(); > > acpi_pci_link_init(); > > @@ -1934,6 +1994,20 @@ int __init acpi_scan_init(void) > > > > acpi_scan_add_handler(&generic_device_handler); > > > > + /* > > + * If there is STAO table, check whether it needs to ignore the UART > > + * device in SPCR table. > > + */ > > + status = acpi_get_table(ACPI_SIG_STAO, 0, > > + (struct acpi_table_header **)&stao_ptr); > > + if (ACPI_SUCCESS(status)) { > > + if (stao_ptr->header.length > sizeof(struct acpi_table_stao)) > > + printk(KERN_INFO PREFIX "STAO Name List not yet supported."); > > + > > + if (stao_ptr->ignore_uart) > > + acpi_get_spcr_uart_addr(); > > + } > > + > > mutex_lock(&acpi_scan_lock); > > /* > > * Enumerate devices in the ACPI namespace. > > -- > > 2.0.4 > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html