Can a sysfs attribute take a non numeric value in Linux Device Driver? [closed]

Question

I am developing a Linux device driver where I have to pass a string of characters to it using sysfs interface. Can the sysfs attributes accept the data in a string form (something like echo "somedata" > sysfs_interface )?

I have implemented it above, and it seems to be working fine, but I would like to make certain that this is valid (acceptable in the kernel community).

Answer 1

Can the sysfs attributes accepts the data in a string form ...

Yes.
Actually that is what sysfs accepts when you use echo. When you use echo 0 the output is two bytes, 0x30 (the ASCII code for digit zero) and 0x0A (a newline).

For example the GPIO LED interface uses keywords to report and select the trigger.

# cat /sys/class/leds/d8/trigger
none nand-disk mmc0 timer [heartbeat] gpio

(The bracketed keyword indicates the current selection, the heartbeat timer.)

# echo none > /sys/class/leds/d8/trigger
# cat /sys/class/leds/d8/trigger
[none] nand-disk mmc0 timer heartbeat gpio

... (something like echo "somedata" > sysfs_interface )

You don't even need to use the quote marks.
See the above example of setting the LED trigger to none.

---

ADDENDUM

these are the custom interfaces ...

No, this is in mainline .

... but what about the one provided by the subsystem?

The authoritative answer is from Linux Documentation/filesystems/sysfs.txt:

Attributes should be ASCII text files, preferably with only one value
per file.