Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752012AbcCXPIe (ORCPT ); Thu, 24 Mar 2016 11:08:34 -0400 Received: from mail-lb0-f196.google.com ([209.85.217.196]:33565 "EHLO mail-lb0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750772AbcCXPI0 (ORCPT ); Thu, 24 Mar 2016 11:08:26 -0400 MIME-Version: 1.0 In-Reply-To: <1458830676-27075-2-git-send-email-shannon.zhao@linaro.org> References: <1458830676-27075-1-git-send-email-shannon.zhao@linaro.org> <1458830676-27075-2-git-send-email-shannon.zhao@linaro.org> Date: Thu, 24 Mar 2016 16:08:23 +0100 X-Google-Sender-Auth: 5isDvKxITB7Ooo5iJQZv-9YGQR4 Message-ID: Subject: Re: [PATCH v7 01/17] Xen: ACPI: Hide UART used by Xen From: "Rafael J. Wysocki" To: Shannon Zhao Cc: "linux-arm-kernel@lists.infradead.org" , stefano.stabellini@citrix.com, david.vrabel@citrix.com, "devicetree@vger.kernel.org" , linux-efi@vger.kernel.org, Linux Kernel Mailing List , Catalin Marinas , Will Deacon , julien.grall@arm.com, peter.huangpeng@huawei.com, xen-devel@lists.xen.org, Shannon Zhao , "Rafael J. Wysocki" , Len Brown , "open list:ACPI" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4656 Lines: 131 On Thu, Mar 24, 2016 at 3:44 PM, Shannon Zhao wrote: > 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" (supporter:ACPI) > CC: Len Brown (supporter:ACPI) > CC: linux-acpi@vger.kernel.org (open list:ACPI) > Signed-off-by: Shannon Zhao > --- > drivers/acpi/scan.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 68 insertions(+) > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index 5f28cf7..e96a058 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -45,6 +45,7 @@ static LIST_HEAD(acpi_scan_handlers_list); > DEFINE_MUTEX(acpi_device_lock); > LIST_HEAD(acpi_wakeup_device_list); > static DEFINE_MUTEX(acpi_hp_context_lock); > +static u64 spcr_uart_addr; > > struct acpi_dep_data { > struct list_head node; > @@ -1453,6 +1454,41 @@ 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 != 0) { > + if (!acpi_has_method(handle, METHOD_NAME__CRS)) > + return false; > + > + status = acpi_walk_resources(handle, METHOD_NAME__CRS, > + acpi_get_resource_memory, &res); > + if (ACPI_FAILURE(status)) > + return false; > + > + if (res.start == spcr_uart_addr) { > + printk(KERN_INFO PREFIX "The UART device in SPCR table will be hidden\n"); > + return true; > + } > + } > + > + return false; > +} > + > static int acpi_bus_type_and_status(acpi_handle handle, int *type, > unsigned long long *sta) > { > @@ -1466,6 +1502,9 @@ 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 +1955,24 @@ static int acpi_bus_scan_fixed(void) > return result < 0 ? result : 0; > } > > +static void acpi_get_spcr_uart_addr(void) static void __init acpi_get_spcr_uart_addr(void) I suppose? Apart from this it looks fine. > +{ > + 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 +1988,20 @@ 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. > --