Messages in this thread | | | From | Bill Richardson <> | Date | Thu, 20 Nov 2014 10:16:03 -0800 | Subject | Re: [PATCH 2/3] mfd: cros_ec: Create sysfs attributes for the ChromeOS EC. |
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On Thu, Nov 20, 2014 at 3:58 AM, Javier Martinez Canillas <javier.martinez@collabora.co.uk> wrote: > > I don't really know why there are two interfaces for this but I guess > that different user-space utilities use one or another. Maybe the > ChromiumOS folks can comment on this.
The /dev/cros_ec interface responds to ioctls and is the primary means by which userspace applications talk to the EC (replacing three really awkward bus-specific libraries). It emits a simplified version string when read so that humans can tell if the EC is alive and speaking the same protocol that the userspace app expects.
The /sys/class/chromeos/cros_ec/* tree was originally envisioned as a way to provide additional human-readable interfaces to a subset of the EC commands, but except for the lightbar it's not often used. The version component here shows all the version-related info that the EC can provide.
I apologize for the poor kernel conventions used here. In my ignorance, I apparently chose the worst code possible to use as a template, and then invented some new stupidness of my own.
Bill -- Art for Art's Sake Engineering for Money
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