Re: [RFC] Adding MTD to device tree

Hello.

Milton Miller wrote:

quoted

quoted

+   h) MTD nodes
+
+   Memory Technology Devices are flash, ROM, and similar chips, often used
+   for solid state file systems on embedded devices.
+
+   Required properties:
+
+    - device_type : has to be "mtd"
+    - compatible : Should be the name of the MTD driver. Currently, this is
+      most likely to be "physmap".
+    - reg : Offset and length of the register set for the device.

quoted

I would prefer to call them something different in the device tree.
The name 'mtd' is very specific to Linux, but the device tree
is a more generic concept.

    "Memory type devices" are specific to Linux? Doubt it. :-)
    In fact, device type "flash" sounds too restrictive.

quoted

I understand that the booting-without-of.txt file is by definition
Linux specific as well, but we should be prepared for making parts
of it a OS independent binding at the point where we put the same
device nodes into actual OF implementations that able to boot
different operating systems.

quoted

I would prefer a naming that has 

quoted

  Required properties:
   - device_type : one of "nand-flash", "nor-flash", or "rom".
   - model : an identifier for the actual controller chip used.
   - compatible : Should be the name of the MTD driver. For
     type "rom", this is most likely "physmap".

I'm with your suggestion for device_type and model, but not 
compatable.   "physmap"?  What kind of device is that?  A 

    Directly mapped NOR flash or ROM I think.

command set name, maybe with a width, would be 

    That'd be pretty useless if you don't let Linux know which MTD *map* 
driver to use. And I have specified the "bank-width" prop.

appropriate.   Physmap is the name of another linux driver.   

    And the role of the "compatible" prop is exactly to help OS in selecting 
the driver.

Something like direct or linear might be appropriate for a rom, 
where just address and length appear.

    I agree that "linear" or "direct" may be better variants.

 Even rom would be better than physmap.

    Doubt it since the ROM is the only one thing (and even the least probable) 
that we're going to support.

milton

WBR, Sergei