Re: [PATCH 08/13] reset: Add a reset controller driver for the Lantiq XWAY based SoCs

[Hauke Mehrtens <hauke@xxxxxxxxxx>]

On 04/20/2017 04:54 PM, Rob Herring wrote:
> On Mon, Apr 17, 2017 at 09:29:37PM +0200, Hauke Mehrtens wrote:
>> From: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
>>
>> The reset controllers (on xRX200 and newer SoCs have two of them) are
>> provided by the RCU module. This was initially implemented as a simple
>> reset controller. However, the RCU module provides more functionality
>> (ethernet GPHYs, USB PHY, etc.), which makes it a MFD device.
>> The old reset controller driver implementation from
>> arch/mips/lantiq/xway/reset.c did not honor this fact.
>>
>> For some devices the request and the status bits are different.
>>
>> Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
>> ---
>>  .../devicetree/bindings/reset/lantiq,rcu-reset.txt |  43 ++++
>>  arch/mips/lantiq/xway/reset.c                      |  68 ------
>>  drivers/reset/Kconfig                              |   6 +
>>  drivers/reset/Makefile                             |   1 +
>>  drivers/reset/reset-lantiq-rcu.c                   | 231 +++++++++++++++++++++
>>  5 files changed, 281 insertions(+), 68 deletions(-)
>>  create mode 100644 Documentation/devicetree/bindings/reset/lantiq,rcu-reset.txt
>>  create mode 100644 drivers/reset/reset-lantiq-rcu.c
>>
>> diff --git a/Documentation/devicetree/bindings/reset/lantiq,rcu-reset.txt b/Documentation/devicetree/bindings/reset/lantiq,rcu-reset.txt
>> new file mode 100644
>> index 000000000000..7f097d16bbb7
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/reset/lantiq,rcu-reset.txt
>> @@ -0,0 +1,43 @@
>> +Lantiq XWAY SoC RCU reset controller binding
>> +============================================
>> +
>> +This binding describes a reset-controller found on the RCU module on Lantiq
>> +XWAY SoCs.
>> +
>> +
>> +-------------------------------------------------------------------------------
>> +Required properties (controller (parent) node):
>> +- compatible		: Should be "lantiq,rcu-reset"
>> +- lantiq,rcu-syscon	: A phandle to the RCU syscon, the reset register
>> +			  offset and the status register offset.
>> +- #reset-cells		: Specifies the number of cells needed to encode the
>> +			  reset line, should be 1.
>> +
>> +Optional properties:
>> +- reset-status		: The request status bit. For some bits the request bit
>> +			  and the status bit are different. This is depending
>> +			  on the SoC. If the reset-status bit does not match
>> +			  the reset-request bit, put the reset number into the
>> +			  reset-request property and the status bit at the same
>> +			  index into the reset-status property. If no
>> +			  reset-request bit is given here, the driver assume
>> +			  status and request bit are the same.
>> +- reset-request		: The reset request bit, to map it to the reset-status
>> +			  bit.
> 
> These should either be implied by SoC specific compatible or be made 
> part of the reset cells. In the latter case, you still need the SoC 
> specific compatible.

Currently the reset framework only supports a single reset cell to my
knowledge, but I haven't looked into the details, I could extend it to
make it support two.

The SoC which needs this has two reset control register sets and the
bits are specific for each register set. Would a specific compatible
string for each register set ok?

> 
>> +-------------------------------------------------------------------------------
>> +Example for the reset-controllers on the xRX200 SoCs:
>> +	rcu_reset0: rcu_reset {
>> +		compatible = "lantiq,rcu-reset";
>> +		lantiq,rcu-syscon = <&rcu0 0x10 0x14>;
>> +		#reset-cells = <1>;
>> +		reset-request = <31>, <29>, <21>, <19>, <16>, <12>;
>> +		reset-status  = <30>, <28>, <16>, <25>, <5>,  <24>;
>> +	};
>> +
>> +	rcu_reset1: rcu_reset {
>> +		compatible = "lantiq,rcu-reset";
> 
> These 2 blocks are identical? Given different registers sizes, I'd say 
> not. So they should have different compatible strings.

I will remove the second one.

> 
>> +		lantiq,rcu-syscon = <&rcu0 0x48 0x24>;
>> +		#reset-cells = <1>;
>> +	};
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