Hi Rafael, On 13/4/20 22:41, Rafael J. Wysocki wrote: > On Mon, Apr 13, 2020 at 3:46 PM Enric Balletbo i Serra > <enric.balletbo@xxxxxxxxxxxxx> wrote: >> >> This driver attaches to the ChromeOS ACPI device and then exports the values >> reported by the ACPI in a sysfs directory. These values are not exported >> via the standard ACPI tables, hence a specific driver is needed to do >> it. > > So how exactly are they exported? > They are exported through sysfs. >> The ACPI values are presented in the string form (numbers as decimal >> values) or binary blobs, and can be accessed as the contents of the >> appropriate read only files in the standard ACPI devices sysfs directory tree. > > My understanding based on a cursory look at the patch is that there is > an ACPI device with _HID equal to "GGL0001" and one or more special > methods under it that return values which you want to export over > sysfs as binary attributes. They appear to be read-only. > Exactly, there is an ACPI device equal to "GGL0001" and one special method called MLST that returns a list of the other control methods supported by the Chrome OS hardware device. The driver calls the special MLST method and goes through the list. > I guess that these data are to be consubed by user space? > Yes, this is used by user space, to be more specific ChromeOS userspace uses it.
