Re: [PATCH v2 3/6] dt/bindings: Add bindings for Tegra GMI controller

[Mirza Krak <mirza.krak@gmail.com>]

2016-08-30 17:02 GMT+02:00 Marcel Ziswiler <marcel.ziswiler@toradex.com>:
> On Wed, 2016-08-24 at 15:37 +0200, Mirza Krak wrote:
>> From: Mirza Krak <mirza.krak@gmail.com>
>>
>> Document the devicetree bindings for the Generic Memory Interface
>> (GMI)
>> bus driver found on Tegra SOCs.
>>
>> Signed-off-by: Mirza Krak <mirza.krak@gmail.com>
>> ---
>> Changes in v2:
>> - Updated examples and some information based on comments from Jon
>> Hunter.
>>
>>  .../devicetree/bindings/bus/nvidia,tegra20-gmi.txt | 132
>> +++++++++++++++++++++
>>  1 file changed, 132 insertions(+)
>>  create mode 100644
>> Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt
>>
>> diff --git a/Documentation/devicetree/bindings/bus/nvidia,tegra20-
>> gmi.txt b/Documentation/devicetree/bindings/bus/nvidia,tegra20-
>> gmi.txt
>> new file mode 100644
>> index 0000000..8c1e15f
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt
>> @@ -0,0 +1,132 @@
>> +Device tree bindings for NVIDIA Tegra Generic Memory Interface bus
>> +
>> +The Generic Memory Interface bus enables memory transfers between
>> internal and
>> +external memory. Can be used to attach various high speed devices
>> such as
>> +synchronous/asynchronous NOR, FPGA, UARTS and more.
>> +
>> +The actual devices are instantiated from the child nodes of a GMI
>> node.
>> +
>> +Required properties:
>> + - compatible : Should contain one of the following:
>> +        For Tegra20 must contain "nvidia,tegra20-gmi".
>> +        For Tegra30 must contain "nvidia,tegra30-gmi".
>> + - reg: Should contain GMI controller registers location and length.
>> + - clocks: Must contain an entry for each entry in clock-names.
>> + - clock-names: Must include the following entries: "gmi"
>> + - resets : Must contain an entry for each entry in reset-names.
>> + - reset-names : Must include the following entries: "gmi"
>> + - #address-cells: The number of cells used to represent physical
>> base
>> +   addresses in the GMI address space. Should be 1.
>> + - #size-cells: The number of cells used to represent the size of an
>> address
>> +   range in the GMI address space. Should be 1.
>> + - ranges: Must be set up to reflect the memory layout with three
>> integer values
>> +   for each chip-select line in use (only one entry is supported,
>> see below
>> +   comments):
>> +   <cs-number> <physical address of mapping> <size>
>> +
>> +Note that the GMI controller does not have any internal chip-select
>> address
>> +decoding, because of that chip-selects either need to be managed via
>> software
>> +or by employing external chip-select decoding logic.
>> +
>> +If external chip-select logic is used to support multiple devices it
>> is assumed
>> +that the devices use the same timing and so are probably the same
>> type. It also
>> +assumes that they can fit in the 256MB address range. In this case
>> only one
>> +child device is supported which represents the active chip-select
>> line, see
>> +examples for more insight.
>> +
>> +Required child cs node properties:
>> + - reg: First entry should contain the active chip-select number
>> +
>> +Optional child cs node properties:
>> +
>> + - nvidia,snor-data-width-32bit: Use 32bit data-bus, default is
>> 16bit.
>> + - nvidia,snor-mux-mode: Enable address/data MUX mode.
>> + - nvidia,snor-rdy-active-before-data: Assert RDY signal one cycle
>> before data.
>> +   If omitted it will be asserted with data.
>> + - nvidia,snor-rdy-inv: RDY signal is active high
>> + - nvidia,snor-adv-inv: ADV signal is active high
>> + - nvidia,snor-oe-inv: WE/OE signal is active high
>> + - nvidia,snor-cs-inv: CS signal is active high
>> +
>> +  Note that there is some special handling for the timing values.
>> +  From Tegra TRM:
>> +  Programming 0 means 1 clock cycle: actual cycle = programmed cycle
>> + 1
>> +
>> + - nvidia,snor-muxed-width: Number of cycles MUX address/data
>> asserted on the
>> +   bus. Valid values are 0-15, default is 1
>> + - nvidia,snor-hold-width: Number of cycles CE stays asserted after
>> the
>> +   de-assertion of WR_N (in case of SLAVE/MASTER Request) or OE_N
>> +   (in case of MASTER Request). Valid values are 0-15, default is 1
>> + - nvidia,snor-adv-width: Number of cycles during which ADV stays
>> asserted.
>> +   Valid values are 0-15, default is 1.
>> + - nvidia,snor-ce-width: Number of cycles before CE is asserted.
>> +   Valid values are 0-15, default is 4
>> + - nvidia,snor-we-width: Number of cycles during which WE stays
>> asserted.
>> +   Valid values are 0-15, default is 1
>> + - nvidia,snor-oe-width: Number of cycles during which OE stays
>> asserted.
>> +   Valid values are 0-255, default is 1
>> + - nvidia,snor-wait-width: Number of cycles before READY is
>> asserted.
>> +   Valid values are 0-255, default is 3
>> +
>> +Example with two SJA1000 CAN controllers connected to the GMI bus.
>> We wrap the
>> +controllers with a simple-bus node since they are all connected to
>> the same
>> +chip-select (CS4), in this example external address decoding is
>> provided:
>> +
>> +gmi@70090000 {
>
> It's actually 70009000.

I actually noticed this all ready, so should be fixed in the upcoming V3.

Thank you for your review.

Best Regards
Mirza