How to use spi device from another kernel module?

[greg@kroah.com (Greg KH)]

On Tue, Dec 06, 2016 at 09:12:24PM -0800, Joel Fernandes wrote:
> On Tue, Dec 6, 2016 at 11:42 AM, Ran Shalit <ranshalit@gmail.com> wrote:
> > Hello,
> >
> > I have spi device which is registered using spi_register_board_info(),
> > and I would like to get a pointer to this device in some other kernel module.
> >
> > Is there a simple way to get a pointer to pointer to a device , so
> > that we can use it from other module ? (something like i2c_get_adapter
> > for i2c)
> 
> Find out what's the SPI bus number (for the master) and the chip
> select on that SPI master (for the SPI device)
> 
> Then you can use bus_for_each_device on spi_bus_type and find the
> spi_device you're looking for. See the following code for an example
> of how to use bus_for_each_device:
> 
> http://lxr.free-electrons.com/source/drivers/spi/spi.c#L524
> 
> In your check function, just make sure your spi->master->bus_num is
> the bus you want and the spi->chip_select is the chip select
> corresponding to the device you want. If both these conditions are
> satisfied, there you have your spi_device.

Eeek, no, please never do that, use the proper spi apis to get your
needed device.  They are there somewhere, using a "raw"
bus_for_each_device is never the answer unless you are a bus and
iterating over your own device list.

thanks,

greg k-h