Re: Query related to MSR(Magnetic Stripe Reader) Device Driver

[Jonathan Cameron <jic23@kernel.org>]

Greg KH <gregkh@linuxfoundation.org> wrote:

>On Fri, Feb 15, 2013 at 04:48:33PM +0530, Priyaranjan Das wrote:
>> Hi Greg,
>> 
>> On Thu, Jan 31, 2013 at 11:09 AM, Priyaranjan Das
>> <priyaranjan456789@gmail.com> wrote:
>> > Hi Greg,
>> >
>> > On Tue, Jan 29, 2013 at 7:03 PM, Greg KH
><gregkh@linuxfoundation.org> wrote:
>> >> On Mon, Jan 28, 2013 at 03:25:08PM +0530, Priyaranjan Das wrote:
>> >>> Hi Greg,
>> >>>
>> >>> On Tue, Jan 22, 2013 at 10:06 PM, Greg KH
><gregkh@linuxfoundation.org> wrote:
>> >>> > On Tue, Jan 22, 2013 at 03:02:32PM +0530, Priyaranjan Das
>wrote:
>> >>> >> Hi All,
>> >>> >>
>> >>> >> I am working on MSR(Magnetic Stripe Reader) for a product . I
>wish to
>> >>> >> know whether any MSR( Magnetic Stripe/card Reader) driver is
>available
>> >>> >> in the current source or not. I need this for reference. Could
>anyone
>> >>> >> please help me?
>> >>> >
>> >>> > Most of these types of devices that I have worked with always
>show up as
>> >>> > a keyboard device (ps/2 pass-through or a USB hid device.) 
>What type of
>> >>> > interface does your device present to the operating system?
>> >>> >
>> >>>
>> >>> The MSR will be a part of a SoC. It is  a memory mapped device
>hence
>> >>> there is no interface like USB.
>> >>
>> >> Ok, that's different.  But how will your driver want to
>communicate the
>> >> reader data to userspace?  That will probably determine where you
>want
>> >> to put it.
>> >>
>> >> I would recommend making it an input device and sending keystrokes
>that
>> >> you read from the card, so you can properly integrate into
>userspace
>> >> applications that are used to using a card reader.
>> >>
>> >>> MSR IP contains an ADC which the driver will read and interpret
>the
>> >>> data. I am planning to write a Driver for the same. Will this
>driver
>> >>> fall under drivers/mfd/* ?
>> >>
>> >> As per the above, I would think drivers/input/ wouldn't you?
>> >>
>> >> Hope this helps,
>> >>
>> >
>> > Thanks for your help!.
>> >
>> > Yes, you are right, it should be under drivers/input.
>> > I am trying to prepare the design right now.
>> >
>> >
>> 
>> The MSR IP can be also be used either as a general purpose ADC or in
>> Magnetic stripe card reader mode.The IP supports both the modes and
>> provides FIFO for storing ADC data.
>> 
>> I also got to know about IIO subsystem where  ADC drivers are
>> implemented. Our use-case will be to use either Magnetic Stripe
>reader
>> mode or general purpose ADC mode in a given configuration. Can I use
>> IIO subsystem for the Magnetic Stripe driver?
>
>The IIO developers would know best about this, not I, sorry.

The gp ADC stuff will fit nicely in IIO. I am afraid I don't know
 much about these devices. Could you give a brief description 
of what the hardware does and what processing and outputs 
you would want from the driver.


That separation between what is in hardware and what software may dictate how the driver is broken up.

Thanks

Jonathan
>
>greg k-h
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