[linux-cirrus] Re: How to determine if a device is an AMBA device
- From: "Wagner Scott (ST-IN/ENG1.1)" <Scott.Wagner@xxxxxxxxxxxx>
- To: <linux-cirrus@xxxxxxxxxxxxx>
- Date: Wed, 27 Jun 2007 13:17:34 -0400
>> Hello all,
>>
>> It is not clear to me what it means to be an AMBA device.
>>
>> Russell King alluded to this in his post
>>
http://lists.arm.linux.org.uk/pipermail/linux-arm/2006-August/012098.htm
>> l: "Only use an amba_device _IF_ you have a real AMBA device. It's
not
>> for willy nilly random drivers."
>>
>> The case for which I am confused is an external peripheral connected
to
>> a Cirrus Logic EP93xx (ARM920T) address & data bus using the EP93xx
>> static memory controller and one of the external interrupts (/INT1).
>>
>> Is this an AMBA device, which should use amba_driver_register(),
>> amba_device_register(), and friends in ./arch/arm/common/amba.c and
>> ./include/asm/hardware/amba.h, (since it uses the EP93xx's AMBA
static
>> memory and interrupt controllers)?
>>
>See this http://lxr.linux.no/source/arch/arm/mach-ep93xx/core.c?a=arm
>
>the uart inside the chip are AMBA devices, but other devices are
>platform_devices,
>registered using platform_device_register and platform_driver_register.
>> Or is it an "ordinary" device which should use the generic Linux
>> ioremap_nocache() and request_irq() mechanism, as Russell suggests?
>>
>Yep, except you should not call ioremap but let
platform_device_register
do it for you.
Thanks, Jean-Philippe! Is platform_device_register() usage documented
somewhere? Is there an example? Should platform_device_register be
called from the machine init, or may it be called from the (perhaps
modular) driver using it?
Regards,
Scott
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