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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Shannon Zhao <zhaoshenglong@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	linux-efi@vger.kernel.org, Ian Campbell <ian.campbell@citrix.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	xen-devel@lists.xen.org,
	"open list:ACPI" <linux-acpi@vger.kernel.org>,
	julien.grall@arm.com, stefano.stabellini@citrix.com,
	david.vrabel@citrix.com, peter.huangpeng@huawei.com,
	Len Brown <lenb@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	Shannon Zhao <shannon.zhao@linaro.org>
Subject: Re: [PATCH v6 01/17] Xen: ACPI: Hide UART used by Xen
Date: Thu, 17 Mar 2016 13:59:44 +0100	[thread overview]
Message-ID: <CAJZ5v0jw=R4n7qMk4ibZAeC=tkat6O-cgWiQnRb4o02Hy6ehpA__5840.30880495465$1458219670$gmane$org@mail.gmail.com> (raw)
In-Reply-To: <1458208636-12960-2-git-send-email-zhaoshenglong@huawei.com>

On Thu, Mar 17, 2016 at 10:57 AM, Shannon Zhao <zhaoshenglong@huawei.com> wrote:
> From: Shannon Zhao <shannon.zhao@linaro.org>
>
> 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@linaro.org>
> ---
> CC: "Rafael J. Wysocki" <rjw@rjwysocki.net> (supporter:ACPI)
> CC: Len Brown <lenb@kernel.org> (supporter:ACPI)
> CC: linux-acpi@vger.kernel.org (open list:ACPI)
> ---
>  drivers/acpi/scan.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 63 insertions(+)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 5f28cf7..55ceb69 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))
> @@ -1919,6 +1958,8 @@ static int acpi_bus_scan_fixed(void)
>  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 +1975,28 @@ 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) {
> +                       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");
> +               }
> +       }

I'd put the above part into a separate function and call that from
here.  You'd be able to reduce the indentation level then slightly
without using gotos.

Apart from this minor point the patch is fine by me.

> +
>         mutex_lock(&acpi_scan_lock);
>         /*
>          * Enumerate devices in the ACPI namespace.
> --

Thanks,
Rafael

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  parent reply	other threads:[~2016-03-17 12:59 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-17  9:56 [PATCH v6 00/17] Add ACPI support for Xen Dom0 on ARM64 Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 01/17] Xen: ACPI: Hide UART used by Xen Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 02/17] xen/grant-table: Move xlated_setup_gnttab_pages to common place Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 03/17] Xen: xlate: Use page_to_xen_pfn instead of page_to_pfn Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 04/17] arm/xen: Use xen_xlate_map_ballooned_pages to setup grant table Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 05/17] xen: memory : Add new XENMAPSPACE type XENMAPSPACE_dev_mmio Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 06/17] Xen: ARM: Add support for mapping platform device mmio Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 07/17] Xen: ARM: Add support for mapping AMBA " Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 08/17] Xen: public/hvm: sync changes of HVM_PARAM_CALLBACK_VIA ABI from Xen Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 09/17] xen/hvm/params: Add a new delivery type for event-channel in HVM_PARAM_CALLBACK_IRQ Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 10/17] arm/xen: Get event-channel irq through HVM_PARAM when booting with ACPI Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 11/17] ARM: XEN: Move xen_early_init() before efi_init() Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 12/17] ARM64: ACPI: Check if it runs on Xen to enable or disable ACPI Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 13/17] ARM: Xen: Document UEFI support on Xen ARM virtual platforms Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 14/17] XEN: EFI: Move x86 specific codes to architecture directory Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 15/17] ARM64: XEN: Add a function to initialize Xen specific UEFI runtime services Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 16/17] FDT: Add a helper to get the subnode by given name Shannon Zhao
2016-03-17  9:57 ` [PATCH v6 17/17] Xen: EFI: Parse DT parameters for Xen specific UEFI Shannon Zhao
     [not found] ` <1458208636-12960-2-git-send-email-zhaoshenglong@huawei.com>
2016-03-17 12:59   ` Rafael J. Wysocki [this message]
2016-03-24 12:21 ` [PATCH v6 00/17] Add ACPI support for Xen Dom0 on ARM64 Stefano Stabellini

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