diff options
Diffstat (limited to 'Documentation/ABI/stable')
| -rw-r--r-- | Documentation/ABI/stable/sysfs-class-backlight | 20 | ||||
| -rw-r--r-- | Documentation/ABI/stable/sysfs-firmware-efi-vars | 75 |
2 files changed, 95 insertions, 0 deletions
diff --git a/Documentation/ABI/stable/sysfs-class-backlight b/Documentation/ABI/stable/sysfs-class-backlight index 4d637e1c4ff..70302f370e7 100644 --- a/Documentation/ABI/stable/sysfs-class-backlight +++ b/Documentation/ABI/stable/sysfs-class-backlight @@ -34,3 +34,23 @@ Contact: Richard Purdie <rpurdie@rpsys.net> Description: Maximum brightness for <backlight>. Users: HAL + +What: /sys/class/backlight/<backlight>/type +Date: September 2010 +KernelVersion: 2.6.37 +Contact: Matthew Garrett <mjg@redhat.com> +Description: + The type of interface controlled by <backlight>. + "firmware": The driver uses a standard firmware interface + "platform": The driver uses a platform-specific interface + "raw": The driver controls hardware registers directly + + In the general case, when multiple backlight + interfaces are available for a single device, firmware + control should be preferred to platform control should + be preferred to raw control. Using a firmware + interface reduces the probability of confusion with + the hardware and the OS independently updating the + backlight state. Platform interfaces are mostly a + holdover from pre-standardisation of firmware + interfaces. diff --git a/Documentation/ABI/stable/sysfs-firmware-efi-vars b/Documentation/ABI/stable/sysfs-firmware-efi-vars new file mode 100644 index 00000000000..5def20b9019 --- /dev/null +++ b/Documentation/ABI/stable/sysfs-firmware-efi-vars @@ -0,0 +1,75 @@ +What: /sys/firmware/efi/vars +Date: April 2004 +Contact: Matt Domsch <Matt_Domsch@dell.com> +Description: + This directory exposes interfaces for interactive with + EFI variables. For more information on EFI variables, + see 'Variable Services' in the UEFI specification + (section 7.2 in specification version 2.3 Errata D). + + In summary, EFI variables are named, and are classified + into separate namespaces through the use of a vendor + GUID. They also have an arbitrary binary value + associated with them. + + The efivars module enumerates these variables and + creates a separate directory for each one found. Each + directory has a name of the form "<key>-<vendor guid>" + and contains the following files: + + attributes: A read-only text file enumerating the + EFI variable flags. Potential values + include: + + EFI_VARIABLE_NON_VOLATILE + EFI_VARIABLE_BOOTSERVICE_ACCESS + EFI_VARIABLE_RUNTIME_ACCESS + EFI_VARIABLE_HARDWARE_ERROR_RECORD + EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS + + See the EFI documentation for an + explanation of each of these variables. + + data: A read-only binary file that can be read + to attain the value of the EFI variable + + guid: The vendor GUID of the variable. This + should always match the GUID in the + variable's name. + + raw_var: A binary file that can be read to obtain + a structure that contains everything + there is to know about the variable. + For structure definition see "struct + efi_variable" in the kernel sources. + + This file can also be written to in + order to update the value of a variable. + For this to work however, all fields of + the "struct efi_variable" passed must + match byte for byte with the structure + read out of the file, save for the value + portion. + + **Note** the efi_variable structure + read/written with this file contains a + 'long' type that may change widths + depending on your underlying + architecture. + + size: As ASCII representation of the size of + the variable's value. + + + In addition, two other magic binary files are provided + in the top-level directory and are used for adding and + removing variables: + + new_var: Takes a "struct efi_variable" and + instructs the EFI firmware to create a + new variable. + + del_var: Takes a "struct efi_variable" and + instructs the EFI firmware to remove any + variable that has a matching vendor GUID + and variable key name. |