On 11/20/2017 10:56 AM, Sudeep Holla wrote: (trimming)
* case there's no explicit cache node or the cache node itself in the * device tree + * @firmware_node: Shared with of_node. When not using DT, this may contain + * pointers to other firmware based values. Particularly ACPI/PPTT + * unique values. * @disable_sysfs: indicates whether this node is visible to the user via * sysfs or not * @priv: pointer to any private data structure specific to particular @@ -64,8 +67,10 @@ struct cacheinfo { #define CACHE_ALLOCATE_POLICY_MASK \ (CACHE_READ_ALLOCATE | CACHE_WRITE_ALLOCATE) #define CACHE_ID BIT(4) - - struct device_node *of_node; + union { + struct device_node *of_node; + void *firmware_node; + };I would prefer struct device_node *of_node; changed to struct fwnode_handle *fwnode; You can then have struct pptt_fwnode { <.....> /*below fwnode allocated using acpi_alloc_fwnode_static */ struct fwnode_handle *fwnode; }; This gives a good starting point to abstract DT and ACPI. If not now, we can later implement fwnode.ops=pptt_cache_ops and then use get property for both DT and ACPI.
I'm obviously confused why this keeps coming up. On the surface it sounds like a good idea. But then, given that I've actually implemented a portion of it, what becomes clear is that the PPTT isn't a good match. Converting the OF routines to use the fwnode is fairly straightforward, but that doesn't help the ACPI situation other than to create a lot of misleading code (and the possibility of creating nonstandard DSDT entries). The fact that this hasn't been done for other tables MADT/SLIT/SRAT/etc makes me wonder why we should do it for the PPTT?
Particularly, when one considers fwnode is more a DSDT<->DT abstraction and thus has a lot of API surface that simply doesn't make any sense given the PPTT binary tree structure. Given that most of the fwnode routines are translating string properties (for example fwnode_property_read_string()) it might be possible to build a translator of some form which takes DT style properties and attempts to map them to the ACPI PPTT tree. What this adds I can't fathom, beyond the fact that suddenly the fwnode interface is a partial/brittle implementation where a large subset of the fwnode_operations will tend to be degenerate cases. The result likely will be a poorly implemented translator which breaks or is meaningless over a large part of the fwnode API surface.
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