Greg Kroah-Hartman
598cf27219
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Brett A C Sheffield <bacs@librecast.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Luna Jernberg <droidbittin@gmail.com> Tested-by: Ronald Warsow <rwarsow@gmx.de> Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
91 lines
3.0 KiB
Plaintext
91 lines
3.0 KiB
Plaintext
What: /sys/.../message
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Date: October 2021
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KernelVersion: 5.16
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Description:
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Controls the text message displayed on character line displays.
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Reading returns the current message with a trailing newline.
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Writing updates the displayed message. Messages longer than the
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display width will automatically scroll. Trailing newlines in
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input are automatically trimmed.
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Writing an empty string clears the display.
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Example:
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echo "Hello World" > message
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cat message # Returns "Hello World\n"
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What: /sys/.../num_chars
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Date: November 2025
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KernelVersion: 6.18
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Contact: Jean-François Lessard <jefflessard3@gmail.com>
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Description:
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Read-only attribute showing the character width capacity of
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the line display device. Messages longer than this will scroll.
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Example:
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cat num_chars # Returns "16\n" for 16-char display
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What: /sys/.../scroll_step_ms
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Date: October 2021
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KernelVersion: 5.16
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Description:
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Controls the scrolling speed for messages longer than the display
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width, specified in milliseconds per scroll step.
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Setting to 0 disables scrolling. Default is 500ms.
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Example:
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echo "250" > scroll_step_ms # 4Hz scrolling
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cat scroll_step_ms # Returns "250\n"
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What: /sys/.../map_seg7
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Date: January 2024
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KernelVersion: 6.9
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Description:
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Read/write binary blob representing the ASCII-to-7-segment
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display conversion table used by the linedisp driver, as defined
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by struct seg7_conversion_map in <linux/map_to_7segment.h>.
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Only visible on displays with 7-segment capability.
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This attribute is not human-readable. Writes must match the
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struct size exactly, else -EINVAL is returned; reads return the
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entire mapping as a binary blob.
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This interface and its implementation match existing conventions
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used in segment-mapped display drivers since 2005.
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ABI note: This style of binary sysfs attribute *is an exception*
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to current "one value per file, text only" sysfs rules, for
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historical compatibility and driver uniformity. New drivers are
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discouraged from introducing additional binary sysfs ABIs.
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Reference interface guidance:
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- include/uapi/linux/map_to_7segment.h
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What: /sys/.../map_seg14
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Date: January 2024
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KernelVersion: 6.9
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Description:
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Read/write binary blob representing the ASCII-to-14-segment
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display conversion table used by the linedisp driver, as defined
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by struct seg14_conversion_map in <linux/map_to_14segment.h>.
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Only visible on displays with 14-segment capability.
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This attribute is not human-readable. Writes must match the
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struct size exactly, else -EINVAL is returned; reads return the
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entire mapping as a binary blob.
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This interface and its implementation match existing conventions
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used by segment-mapped display drivers since 2005.
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ABI note: This style of binary sysfs attribute *is an exception*
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to current "one value per file, text only" sysfs rules, for
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historical compatibility and driver uniformity. New drivers are
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discouraged from introducing additional binary sysfs ABIs.
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Reference interface guidance:
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- include/uapi/linux/map_to_14segment.h
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