On Monday, March 03, 2014 03:19:36 PM Lv Zheng wrote:
>
> The information contained in _DDN (Dos Device Name) might be useful
> for userspace utilities, this patch thus exports such information
> using "ddn" attribute.
> Note that the "ddn" attribute will be created as long as the _DDN
> identifying object exists, whatever its evaluation succeeds or not.
>
> This patch must modify the code which is using "struct acpi_buffer"
> as the buffer.length must be reset to ACPI_ALLOCATE_BUFFER before
> reusing it to invoke acpi_evaluate_object() again.
>
> Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
> Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
> ---
>
> Documentation/ABI/testing/sysfs-bus-acpi | 7 +++++
> drivers/acpi/scan.c | 47
> +++++++++++++++++++++++++++++- include/acpi/acpi_bus.h |
> 1 +
> 3 files changed, 54 insertions(+), 1 deletion(-)
>
> Patch
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-acpi
> b/Documentation/ABI/testing/sysfs-bus-acpi index 7fa9cbc..db376b8 100644
> --- a/Documentation/ABI/testing/sysfs-bus-acpi
> +++ b/Documentation/ABI/testing/sysfs-bus-acpi
>
> @@ -49,6 +49,13 @@ Description:
> This attribute contains the output of the device object's
> _UID control method, if present.
>
> +What: /sys/bus/acpi/devices/.../ddn
> +Date: February 2014
> +Contact: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
> +Description:
> + This attribute contains the output of the device object's
> + _DDN control method, if present.
> +
>
> What: /sys/bus/acpi/devices/.../eject
> Date: December 2006
> Contact: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 4789c9b..5f039a6 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -662,6 +662,18 @@ static ssize_t description_show(struct device *dev,
>
> }
> static DEVICE_ATTR(description, 0444, description_show, NULL);
>
> +/* sysfs file that shows DOS device name text from the ACPI _DDN method */
> +static ssize_t ddn_show(struct device *dev, struct device_attribute *attr,
> + char *buf) {
> + struct acpi_device *acpi_dev = to_acpi_device(dev);
> +
> + if (acpi_dev->pnp.ddn == NULL)
Please use "if (!acpi_dev->pnp.ddn)"
Also, you can do
return acpi_dev->pnp.ddn ? snprintf(buf, PAGE_SIZE, "%s\n", acpi_dev->pnp.ddn) : 0;
> + return 0;
> +
> + return snprintf(buf, PAGE_SIZE, "%s\n", acpi_dev->pnp.ddn);
> +}
> +static DEVICE_ATTR(ddn, 0444, ddn_show, NULL);
> +
>
> static ssize_t
> acpi_device_sun_show(struct device *dev, struct device_attribute *attr,
>
> char *buf) {
>
> @@ -687,10 +699,11 @@ static DEVICE_ATTR_RO(status);
>
> static int acpi_device_setup_files(struct acpi_device *dev)
> {
>
> - struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
> + struct acpi_buffer buffer;
>
> acpi_status status;
> unsigned long long sun;
> int result = 0;
>
> + union acpi_object *object;
>
> /*
>
> * Devices gotten from FADT don't have a "path" attribute
>
> @@ -715,6 +728,8 @@ static int acpi_device_setup_files(struct acpi_device
> *dev)>
> * If device has _STR, 'description' file is created
> */
>
> if (acpi_has_method(dev->handle, "_STR")) {
>
> + buffer.length = ACPI_ALLOCATE_BUFFER;
> + buffer.pointer = NULL;
>
> status = acpi_evaluate_object(dev->handle, "_STR",
>
> NULL, &buffer);
>
> if (ACPI_FAILURE(status))
>
> @@ -725,6 +740,29 @@ static int acpi_device_setup_files(struct acpi_device
> *dev)>
> goto end;
>
> }
>
> + /*
> + * If device has _DDN, 'ddn' file is created
> + */
> + if (acpi_has_method(dev->handle, "_DDN")) {
> + buffer.length = ACPI_ALLOCATE_BUFFER;
> + buffer.pointer = NULL;
> + status = acpi_evaluate_object_typed(dev->handle, "_DDN",
> + NULL, &buffer,
> + ACPI_TYPE_STRING);
> + if (ACPI_FAILURE(status))
> + buffer.pointer = NULL;
> + object = buffer.pointer;
> + if (object) {
> + dev->pnp.ddn = kstrndup(object->string.pointer,
> + object->string.length,
> + GFP_KERNEL);
Is the string guaranteed to be null-terminated after that?
> + kfree(object);
> + }
> + result = device_create_file(&dev->dev, &dev_attr_ddn);
> + if (result)
> + goto end;
> + }
> +
>
> if (dev->pnp.type.bus_address)
>
> result = device_create_file(&dev->dev, &dev_attr_adr);
>
> if (dev->pnp.unique_id)
>
> @@ -787,6 +825,13 @@ static void acpi_device_remove_files(struct
> acpi_device *dev)>
> device_remove_file(&dev->dev, &dev_attr_description);
>
> }
> /*
>
> + * If device has _DDN, remove 'ddn' file
> + */
> + if (acpi_has_method(dev->handle, "_DDN")) {
> + device_remove_file(&dev->dev, &dev_attr_ddn);
> + kfree(dev->pnp.ddn);
> + }
> + /*
>
> * If device has _EJ0, remove 'eject' file.
> */
>
> if (acpi_has_method(dev->handle, "_EJ0"))
>
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 9d82482..92cab35 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -244,6 +244,7 @@ struct acpi_device_pnp {
>
> acpi_device_name device_name; /* Driver-determined */
> acpi_device_class device_class; /* " */
> union acpi_object *str_obj; /* unicode string for _STR method */
>
> + char *ddn; /* _DDN */
>
> unsigned long sun; /* _SUN */
>
> };
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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