linux-kernel - Re: [RFC PATCH 2/6] DRIVERS: IRQCHIP: CROSSBAR: Add support for Crossbar IP

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Message-Id: <202C69F5-3DEB-4735-9CE3-13B38126BD68@codeaurora.org>
Date:	Thu, 24 Oct 2013 06:00:02 -0500
From:	Kumar Gala <galak@...eaurora.org>
To:	Sricharan R <r.sricharan@...com>
Cc:	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-doc@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-omap@...r.kernel.org>, <tglx@...utronix.de>,
	<linus.walleij@...aro.org>, <santosh.shilimkar@...com>,
	<linux@....linux.org.uk>, <tony@...mide.com>, <rnayak@...com>,
	<marc.zyngier@....com>, <grant.likely@...aro.org>,
	<rob.herring@...xeda.com>, <mark.rutland@....com>
Subject: Re: [RFC PATCH 2/6] DRIVERS: IRQCHIP: CROSSBAR: Add support for Crossbar IP


On Oct 24, 2013, at 5:43 AM, Sricharan R wrote:

> Hi Kumar,
> 
> On Thursday 24 October 2013 03:03 PM, Kumar Gala wrote:
>> On Sep 30, 2013, at 8:59 AM, Sricharan R wrote:
>> 
>>> Some socs have a large number of interrupts requests to service
>>> the needs of its many peripherals and subsystems. All of the
>>> interrupt lines from the subsystems are not needed at the same
>>> time, so they have to be muxed to the irq-controller appropriately.
>>> In such places a interrupt controllers are preceded by an CROSSBAR
>>> that provides flexibility in muxing the device requests to the controller
>>> inputs.
>>> 
>>> This driver takes care a allocating a free irq and then configuring the
>>> crossbar IP as a part of the mpu's irqchip callbacks. crossbar_init should
>>> be called right before the irqchip_init, so that it is setup to handle the
>>> irqchip callbacks.
>>> 
>>> Cc: Thomas Gleixner <tglx@...utronix.de>
>>> Cc: Linus Walleij <linus.walleij@...aro.org>
>>> Cc: Santosh Shilimkar <santosh.shilimkar@...com>
>>> Cc: Russell King <linux@....linux.org.uk>
>>> Cc: Tony Lindgren <tony@...mide.com>
>>> Cc: Rajendra Nayak <rnayak@...com>
>>> Cc: Marc Zyngier <marc.zyngier@....com>
>>> Cc: Grant Likely <grant.likely@...aro.org>
>>> Cc: Rob Herring <rob.herring@...xeda.com>
>>> Signed-off-by: Sricharan R <r.sricharan@...com>
>>> ---
>>> .../devicetree/bindings/arm/omap/crossbar.txt      |   27 +++
>>> drivers/irqchip/Kconfig                            |    8 +
>>> drivers/irqchip/Makefile                           |    1 +
>>> drivers/irqchip/irq-crossbar.c                     |  195 ++++++++++++++++++++
>>> include/linux/irqchip/irq-crossbar.h               |   11 ++
>>> 5 files changed, 242 insertions(+)
>>> create mode 100644 Documentation/devicetree/bindings/arm/omap/crossbar.txt
>>> create mode 100644 drivers/irqchip/irq-crossbar.c
>>> create mode 100644 include/linux/irqchip/irq-crossbar.h
>>> 
>>> diff --git a/Documentation/devicetree/bindings/arm/omap/crossbar.txt b/Documentation/devicetree/bindings/arm/omap/crossbar.txt
>>> new file mode 100644
>>> index 0000000..cdec2cd
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/arm/omap/crossbar.txt
>>> @@ -0,0 +1,27 @@
>>> +Some socs have a large number of interrupts requests to service
>>> +the needs of its many peripherals and subsystems. All of the
>>> +interrupt lines from the subsystems are not needed at the same
>>> +time, so they have to be muxed to the irq-controller appropriately.
>>> +In such places a interrupt controllers are preceded by an CROSSBAR
>>> +that provides flexibility in muxing the device requests to the controller
>>> +inputs.
>>> +
>>> +Required properties:
>>> +- compatible : Should be "ti,irq-crossbar"
>>> +- reg: Base address and the size of the crossbar registers.
>>> +- max-irqs: Total number of irqs available at the interrupt controller.
>> Should be 'ti,max-irqs
> Ok, will correct.
>>> +- reg-size: Size of a individual register in bytes. Every individual
>>> +	    register is assumed to be of same size. Valid sizes are 1, 2, 4.
>> Is this something that really needs to be encoded in the dts?
>> 
>> If we keep it should be ti,reg-size
> Currently, this is the only IP with a fixed register-size.
> So this can be in the driver also. I thought keeping it
> DT will avoid any hard-coding in driver.

I'd go with less in the DT at this point, if in the future you need this you can always add it later.

>>> +- irqs-reserved: List of the reserved irq lines that are not muxed using
>>> +		 crossbar. These interrupt lines are reserved in the soc,
>>> +		 so crossbar bar driver should not consider them as free
>>> +		 lines.
>>> +
>> ti,irqs-reserved
> Ok, will correct
>>> +Examples:
>>> +		crossbar_mpu: @4a020000 {
>> Did you mean for there to be a label and no node name?
>> 
> ya, name is missing. Will add.
>>> +			compatible = "ti,irq-crossbar";
>>> +			reg = <0x4a002a48 0x130>;
>>> +			max-irqs = <160>;
>>> +			reg-size = <2>;
>>> +			irqs-reserved = <0 1 2 3 5 6 131 132 139 140>;
>>> +		};
> 
> Regards,
> Sricharan

- 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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