Re: [PATCH v3 06/11] memory: atmel-ebi: add DT bindings documentation

[Boris Brezillon]

On Wed, 3 Dec 2014 15:56:54 +0100
Nicolas Ferre <nicolas.ferre@xxxxxxxxx> wrote:

> Le 01/12/2014 11:27, Boris Brezillon a Ãcrit :
> > The EBI (External Bus Interface) is used to access external peripherals
> > (NOR, SRAM, NAND, and other specific devices like ethernet controllers).
> > Each device is assigned a CS line and an address range and can have its
> > own configuration (timings, access mode, bus width, ...).
> > This driver provides a generic DT binding to configure a device according
> > to its requirements.
> > For specific device controllers (like the NAND one) the SMC timings
> > should be configured by the controller driver through the matrix and smc
> > syscon regmaps.
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> > ---
> >  .../bindings/memory-controllers/atmel-ebi.txt      | 155 +++++++++++++++++++++
> >  1 file changed, 155 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/memory-controllers/atmel-ebi.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/memory-controllers/atmel-ebi.txt b/Documentation/devicetree/bindings/memory-controllers/atmel-ebi.txt
> > new file mode 100644
> > index 0000000..3749ea1
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/memory-controllers/atmel-ebi.txt
> > @@ -0,0 +1,155 @@
> > +* Device tree bindings for Atmel EBI
> > +
> > +The External Bus Interface (EBI) controller is a bus where you can connect
> > +asynchronous (NAND, NOR, SRAM, ....) and synchronous memories (SDR/DDR SDRAMs).
> > +The EBI provides a glue-less interface to asynchronous memories though the SMC
> > +(Static Memory Controller).
> > +Synchronous memories (and some asynchronous memories like NANDs) can be
> > +attached to specialized controllers which are responsible for configuring the
> > +bus appropriately according to the connected device.
> > +In the other hand, the bus interface can be automated for simple asynchronous
> > +devices.
> > +
> > +Required properties:
> > +
> > +- compatible:		"atmel,at91sam9260-ebi"
> > +			"atmel,at91sam9261-ebi"
> > +			"atmel,at91sam9263-ebi0"
> > +			"atmel,at91sam9263-ebi1"
> 
> Ditto: 9263 twice.

Actually that's not a duplicated compatible (see the ebi0/ebi1 at the
end): sam9263 embeds 2 EBIs, and they have different numbers of chip
selects, hence the different compatible string.

I'll add an "atmel,at91sam9rl-ebi" string.

> 
> > +			"atmel,at91sam9g45-ebi"
> > +			"atmel,at91sam9x5-ebi"
> > +			"atmel,sama5d3-ebi"
> > +
> > +- reg:			Contains offset/length value for EBI memory mapping.
> > +			This property might contain several entries if the EBI
> > +			memory range is not contiguous
> > +
> > +- #address-cells:	Must be 2.
> > +			The first cell encodes the CS.
> > +			The second cell encode the offset into the CS memory
> > +			range.
> > +
> > +- #size-cells:		Must be set to 1.
> > +
> > +- ranges:		Encodes CS to memory region association.
> > +
> > +- clocks:		Clock feeding the EBI controller.
> > +			See clock-bindings.txt
> > +
> > +Child chip-select (cs) nodes contain the memory devices nodes connected to
> > +such as NOR (e.g. cfi-flash) and NAND.
> > +There might be board specific devices like FPGAs.
> > +You'll define you device requirements in these child nodes.
> > +
> > +Required child cs node properties:
> > +
> > +- #address-cells:	Must be 2.
> > +
> > +- #size-cells:		Must be 1.
> > +
> > +- ranges:		Empty property indicating that child nodes can inherit
> > +			memory layout.
> > +
> > +Optional child cs node properties:
> > +- atmel,generic-dev		boolean property specifying if the device is
> > +				a generic device.
> > +				The following properties are only parsed if
> > +				this property is present.
> > +				Specialized devices are attached to specialized
> > +				controllers which are responsible for
> > +				configuring the bus appropriately.
> > +				Here are some examples of specialized
> > +				controllers: NAND, CompactFlash, SDR-SDRAM.
> > +
> > +- atmel,bus-width:		width of the asynchronous device's data bus
> > +				8, 16 or 32.
> > +				8 if not present.
> > +
> > +- atmel,byte-access-type	"write" or "select" (see Atmel datasheet).
> > +				"select" if not present.
> > +
> > +- atmel,read-mode		"nrd" or "ncs".
> > +				"ncs" is not present.
> > +
> > +- atmel,write-mode		"nwe" or "ncs".
> > +				"ncs" is not present.
> > +
> > +- atmel,exnw-mode		"disabled", "frozen" or "ready".
> > +				"disabled" if not present.
> > +
> > +- atmel,page-mode		enable page mode if present. The provided value
> > +				defines the page size (supported values: 4, 8,
> > +				16 and 32).
> > +
> > +Optional device timings expressed in nanoseconds (if the property is not
> > +present 0 is assumed):
> > +
> > +- atmel,ncs-rd-setup-ns
> > +- atmel,nrd-setup-ns
> > +- atmel,ncs-wr-setup-ns
> > +- atmel,nwe-setup-ns
> > +- atmel,ncs-rd-pulse-ns
> > +- atmel,nrd-pulse-ns
> > +- atmel,ncs-wr-pulse-ns
> > +- atmel,nwe-pulse-ns
> > +- atmel,nwe-cycle-ns
> > +- atmel,nrd-cycle-ns
> > +- atmel,tdf-ns
> > +
> > +- atmel,tdf-optimized		data float optimized mode. If present the data
> > +				float time is optimized depending on the next
> > +				device being accessed (next device setup
> > +				time is substracted to the current devive data
> 
> Typo: subtract, device

Yep, I'll those typos.




-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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