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Message-ID: <50595BF0.2010002@jp.fujitsu.com>
Date: Wed, 19 Sep 2012 14:45:20 +0900
From: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To: Lance Ortiz <lance.ortiz@...com>
CC: <rob@...dley.net>, <lenb@...nel.org>, <linux-doc@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH] ACPI: Add new sysfs interface to export device description
Hi Lance,
2012/09/08 1:28, Lance Ortiz wrote:
> Add support to export the device description obtained from the ACPI _STR
> method, if one exists for a device, to user-space via a sysfs interface.
> This new interface provides a standard and platform neutral way for users
> to obtain the description text stored in the ACPI _STR method. If no
> _STR method exists for the device, no sysfs 'description' file will be
> created. The 'description' file will be located in the /sys/devices/
> directory using the device's path.
>
> /sys/device/<bus>/<bridge path>/<device path>.../firmware_node/description
>
> Example:
>
> /sys/devices/pci0000:00/0000:00.07.0/0000:0e:00.0/firmware_node/description
>
> It can also be located using the ACPI device path, for example:
>
> /sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/PNP0A08:00/device:13/device:15/description
> /sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/ACPI0004:01/ACPI0007:02/description
>
> Execute the 'cat' command on the 'description' file to obtain the
> description string for that device.
>
> This patch also includes documentation describing how the new sysfs
> interface works
>
> Signed-off-by: Lance Ortiz <lance.ortiz@...com>
> ---
Tested-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
There is a comment as follows.
> .../ABI/testing/sysfs-devices-firmware_node | 17 ++++++
> drivers/acpi/scan.c | 58 +++++++++++++++++++-
> include/acpi/acpi_bus.h | 1 +
> 3 files changed, 74 insertions(+), 2 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-devices-firmware_node
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-firmware_node b/Documentation/ABI/testing/sysfs-devices-firmware_node
> new file mode 100644
> index 0000000..46badc9
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-firmware_node
> @@ -0,0 +1,17 @@
> +What: /sys/devices/.../firmware_node/
> +Date: September 2012
> +Contact: <>
> +Description:
> + The /sys/devices/.../firmware_node directory contains attributes
> + allowing the user space to check and modify some firmware
> + related properties of given device.
> +
> +What: /sys/devices/.../firmware_node/description
> +Date: September 2012
> +Contact: Lance Ortiz <lance.ortiz@...com>
> +Description:
> + The /sys/devices/.../firmware/description attribute contains a string
> + that describes the device as provided by the _STR method in the ACPI
> + namespace. This attribute is read-only. If the device does not have
> + an _STR method associated with it in the ACPI namespace, this
> + attribute is not present.
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index c8a1f3b..c9c91e1 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -10,6 +10,7 @@
> #include <linux/signal.h>
> #include <linux/kthread.h>
> #include <linux/dmi.h>
> +#include <linux/nls.h>
>
> #include <acpi/acpi_drivers.h>
>
> @@ -192,8 +193,38 @@ end:
> }
> static DEVICE_ATTR(path, 0444, acpi_device_path_show, NULL);
>
> +/* sysfs file that shows description text from the ACPI _STR method */
> +static ssize_t description_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf) {
> + struct acpi_device *acpi_dev = to_acpi_device(dev);
> + int result;
> +
> + if (acpi_dev->pnp.str_obj == NULL) {
> + result = sprintf(buf, "No Description\n");
> + goto end;
> + }
> +
> + /*
> + * The _STR object contains a Unicode identifier for a device.
> + * We need to convert to utf-8 so it can be displayed.
> + */
> + result = utf16s_to_utf8s(
> + (wchar_t *)acpi_dev->pnp.str_obj->buffer.pointer,
> + acpi_dev->pnp.str_obj->buffer.length,
> + UTF16_LITTLE_ENDIAN, buf,
> + PAGE_SIZE);
> +
> + buf[result++] = '\n';
> +
> +end:
> + return result;
> +}
> +static DEVICE_ATTR(description, 0444, description_show, NULL);
> +
> static int acpi_device_setup_files(struct acpi_device *dev)
> {
> + struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
> acpi_status status;
> acpi_handle temp;
> int result = 0;
> @@ -217,6 +248,21 @@ static int acpi_device_setup_files(struct acpi_device *dev)
> goto end;
> }
>
> + /*
> + * If device has _STR, 'description' file is created
> + */
> + status = acpi_get_handle(dev->handle, "_STR", &temp);
> + if (ACPI_SUCCESS(status)) {
> + status = acpi_evaluate_object(dev->handle, "_STR",
> + NULL, &buffer);
> + if (ACPI_FAILURE(status))
> + buffer.pointer = NULL;
> + dev->pnp.str_obj = buffer.pointer;
> + result = device_create_file(&dev->dev, &dev_attr_description);
A description sysfs is created even if "acpi_evaluate_object()" fails.
Why do you create it in this case?
Thanks,
Yasuaki Ishimatsu
> + if (result)
> + goto end;
> + }
> +
> /*
> * If device has _EJ0, 'eject' file is created that is used to trigger
> * hot-removal function from userland.
> @@ -234,8 +280,16 @@ static void acpi_device_remove_files(struct acpi_device *dev)
> acpi_handle temp;
>
> /*
> - * If device has _EJ0, 'eject' file is created that is used to trigger
> - * hot-removal function from userland.
> + * If device has _STR, remove 'description' file
> + */
> + status = acpi_get_handle(dev->handle, "_STR", &temp);
> + if (ACPI_SUCCESS(status)) {
> + if (dev->pnp.str_obj != NULL)
> + kfree(dev->pnp.str_obj);
> + device_remove_file(&dev->dev, &dev_attr_description);
> + }
> + /*
> + * If device has _EJ0, remove 'eject' file.
> */
> status = acpi_get_handle(dev->handle, "_EJ0", &temp);
> if (ACPI_SUCCESS(status))
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 9e6e1c6..12172d5 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -209,6 +209,7 @@ struct acpi_device_pnp {
> struct list_head ids; /* _HID and _CIDs */
> acpi_device_name device_name; /* Driver-determined */
> acpi_device_class device_class; /* " */
> + union acpi_object *str_obj; /* unicode string for _STR method */
> };
>
> #define acpi_device_bid(d) ((d)->pnp.bus_id)
>
--
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