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

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

[Priyaranjan Das]

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?

Regards,
Priyaranjan

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

[Greg KH]

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.

greg k-h

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

[Jonathan Cameron]

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

[Lars-Peter Clausen]

On 02/15/2013 12:18 PM, 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?

Hi,

Well for the ADC functionality it certainly makes sense to use the IIO
framework. The magnetic stripe reader functionality should probably go into
drivers/input. How to do this exactly depends a bit on how exactly the
hardware works. A good idea is probably to use a mfd driver which
instantiates both the input and the IIO driver and does some arbitration
between them. If the magnetic stripe reader is a feature that's build on top
of the ADC functionality you could use the IIO in-kernel API to do ADC
conversions from your input driver. If the ADC and magnetic stripe reader
mode are exclusive-or it probably makes sense to only instantiate one of
them at a time from the MFD driver.

- Lars

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

[Priyaranjan Das]

Hi Jonathan,Lars,

>>>
>>
>> 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?
>
> Hi,
>
> Well for the ADC functionality it certainly makes sense to use the IIO
> framework. The magnetic stripe reader functionality should probably go into
> drivers/input. How to do this exactly depends a bit on how exactly the
> hardware works. A good idea is probably to use a mfd driver which
> instantiates both the input and the IIO driver and does some arbitration
> between them. If the magnetic stripe reader is a feature that's build on top
> of the ADC functionality you could use the IIO in-kernel API to do ADC
> conversions from your input driver. If the ADC and magnetic stripe reader
> mode are exclusive-or it probably makes sense to only instantiate one of
> them at a time from the MFD driver.
>

The Hardware consists of an ADC and an in-built FIFO in it. The Device
can either be configured  as a Magnetic stripe reader or a GPADC.
After the ADC conversion,the data will be saved in the FIFO and the
driver has to read it and send it to the upper layers.Here the ADC and
Magnetic Stripe reader functionality are exclusively-or. In MSR mode,
the FIFO shall contain the track data for magnetic stripe card. This
data will be given to input subsystem.

To summarize below is my understanding:
1) drivers/input/misc: shall have the MSR driver.
2) drivers/iio/adc:   shall have the GPADC driver.
3) drivers/mfd:     shall support both above drivers and does arbitration.

Regards,
Priyaranjan

PS: Complete discussion can be found at [1]

[1] http://marc.info/?t=135884722400002&r=1&w=2