linux-kernel - Re: [PATCH 1/2] hwspinlock/omap: add support for dt nodes

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Date:	Wed, 4 Sep 2013 09:46:19 -0500
From:	Kumar Gala <galak@...eaurora.org>
To:	Suman Anna <s-anna@...com>
Cc:	Ohad Ben-Cohen <ohad@...ery.com>, Tony Lindgren <tony@...mide.com>,
	Benoit Cousson <bcousson@...libre.com>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/2] hwspinlock/omap: add support for dt nodes


On Sep 3, 2013, at 5:34 PM, Suman Anna wrote:

> Kumar,
> 
>>> 
>>> On 09/03/2013 01:50 PM, Kumar Gala wrote:
>>>> 
>>>> On Sep 3, 2013, at 12:52 PM, Suman Anna wrote:
>>>> 
>>>>> HwSpinlock IP is present only on OMAP4 and other newer SoCs,
>>>>> which are all device-tree boot only. This patch adds the
>>>>> base support for parsing the DT nodes, and removes the code
>>>>> dealing with the traditional platform device instantiation.
>>>>> 
>>>>> Signed-off-by: Suman Anna <s-anna@...com>
>>>>> ---
>>>>> .../devicetree/bindings/hwlock/omap-hwspinlock.txt | 28 ++++++++++
>>>>> arch/arm/mach-omap2/Makefile                       |  3 --
>>>>> arch/arm/mach-omap2/hwspinlock.c                   | 60 ----------------------
>>>>> drivers/hwspinlock/omap_hwspinlock.c               | 21 ++++++--
>>>>> 4 files changed, 45 insertions(+), 67 deletions(-)
>>>>> create mode 100644 Documentation/devicetree/bindings/hwlock/omap-hwspinlock.txt
>>>>> delete mode 100644 arch/arm/mach-omap2/hwspinlock.c
>>>>> 
>>>>> diff --git a/Documentation/devicetree/bindings/hwlock/omap-hwspinlock.txt b/Documentation/devicetree/bindings/hwlock/omap-hwspinlock.txt
>>>>> new file mode 100644
>>>>> index 0000000..adfb8ad
>>>>> --- /dev/null
>>>>> +++ b/Documentation/devicetree/bindings/hwlock/omap-hwspinlock.txt
>>>>> @@ -0,0 +1,28 @@
>>>>> +OMAP4+ HwSpinlock Driver
>>>>> +
>>>>> +Required properties:
>>>>> +- compatible:		Currently supports only "ti,omap4-hwspinlock" for
>>>>> +				OMAP44xx, OMAP54xx, AM33xx, AM43xx, DRA7xx SoCs
>>>>> +- reg:			Contains the hwspinlock register address range (base
>>>>> +			address and length)
>>>>> +- ti,hwmods:		Name of the hwmod associated with the hwspinlock device
>>>>> +
>>>>> +Optional properties:
>>>>> +- base_id:		Base Id for the locks for a particular hwspinlock
>>>>> +			device. If not mentioned, a default value of 0 is used.
>>>>> +			This property is mandatory ONLY if a SoC has several
>>>>> +			hwspinlock devices. There are currently no such OMAP
>>>>> +			SoCs.
>>>> 
>>>> Should this be ti,base_id ? [ I know its kinda generic in its intent for any SoC w/multiple blocks ]
>>> 
>>> I didn't add the "ti," prefix exactly for the same reason - it is
>>> generic w.r.t the hwspinlock core irrespective of the SoC family, and
>>> there is nothing ti or OMAP specific about it. I have added it to keep
>>> the DT node definition in sync with the driver code. If it is too
>>> generic a name, it can always be renamed as hwlock_base_id. This will be
>>> SoC agnostic property for the hwspinlock driver. What do you think?
>> 
>> I'm wondering if we should use cell-index for this purpose.
> 
> I didn't get you completely. Do you intend to compute the base_id using
> cell-index and number of locks (which may be a separate field altogether
> if this information cannot be read from the h/w)? My understanding is
> that cell-index is primarily used for identifying the h/w instance number.

I was suggesting using cell-index instead of base_id.  What we should probably due is have a devicetree/bindings/hwlock/hwlock.txt that would describe generic properties like this and just reference that in the omap binding spec.

I'm thinking if we dont use cell-index, that it should probably be hwlock-base-id

- k

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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