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GPMC example device driver for an FPGA

Staphae
Prodigy 125 points
Other Parts Discussed in Thread: AM3517

I am writing a device driver for an FPGA connected to the GPMC bus. I am try to adapt the smsc911x device driver for my FPGA device driver. However, the smsc911x is a network device driver and the FPGA is a character driver i believe. I have a skeleton device driver with the init & exit functions which in turn call the platform_driver_register and platform_driver_unregister. However, the probe, remove and shutdown functions that should be called when the driver is registered and unregistered never gets called. I have read some where that i need to edit a board file in arc/arm/mach-omap2/   directory but i don't know what to edit in the board file.  How do i specify the read/write callbacks that will be called back when the user-space program opens the driver for read/write operation. In the smsc911x this is done using an instance of the net device driver framework. Can anyone provide a bit of an insight that could help me. Thanks

  • 0
    TI__Expert 8180 points

    Hi,

    You must register the device for your driver, please refer to any board file (e.g board-omap3evm.c file) where you will find function "platform_device_register" being called. The most important point you must make sure that, the "name" used in both "platform_device" (in board file) and "platform_driver" (driver file) must be same.

     

    Thanks,

    Vaibhav

  • 0 in reply to Vaibhav Hiremath
    Intellectual 320 points

    I’m trying to do (almost) exactly the same: use GPMC to read/write an array of 16 bit-wide, configuration registers located inside an FPGA chip.

    The technology I use is the Sitara AM3517 SoC from TI. My target development board is LogicPD’s eXperimenter board fitted with LogicPD’s AM3517 SOM. The SOM has a NAND flash memory connected to CS0* or (optionally) CS2* select lines. So what I did was to duplicate the initialization code from the NAND chip, but for CS1 instead of CS0/2. All I got so far were ‘device busy’ result code when my module calls the gpmc_cs_write_reg() function. 

    I can’t figure out why: I tried using CS3* and it's reported as busy.  I searched for documents for GPMC ‘howto’ and source docs but the whole library does not seem very well documented. Is there some documentation about gpmc kernel functions? 

    Thanks,

    Yves McDonald