On Wed, Dec 7, 2016 at 8:21 PM, Ran Shalit [off-list ref] wrote:

On Wed, Dec 7, 2016 at 7:26 PM, Ran Shalit [off-list ref] wrote:

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On Wed, Dec 7, 2016 at 6:58 PM, Joel Fernandes [off-list ref] wrote:

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On Tue, Dec 6, 2016 at 11:02 PM, Greg KH [off-list ref] wrote:

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On Tue, Dec 06, 2016 at 09:12:24PM -0800, Joel Fernandes wrote:

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On Tue, Dec 6, 2016 at 11:42 AM, Ran Shalit [off-list ref] wrote:

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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:

Hi,

I did try using this method with the following call:

bus_for_each_dev(&spi_bus_type, NULL, NULL, spi_device_found);

static int spi_device_found(struct device *dev, void *data)
{
    struct spi_device *spi = container_of(dev, struct spi_device, dev);

    printk(":      %s %s %dkHz %d bits mode=0x%02X\n",
        spi->modalias, dev_name(dev), spi->max_speed_hz/1000,
        spi->bits_per_word, spi->mode);

    return 0;
}

But for some reason the list is empty, although I do have devices
registered successfuly with spi_register_driver.
Using the same method with i2c works well, not sure why it doesn't
list anything with spi.

Thanks,
Ran

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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.

Yes I completely agree, maybe I assumed too much and thought he was
trying to do this for some quick debugging from some kernel module,
and was just looking for a quick and dirty way to get to a spi_device.
Was not really suggesting this for production code. :)

If I may please ask one more thing on this issue, just for my understanding.
Before trying the above suggestions, I made the following trial (which
I know is quick and dirty ):

I copied the pointer to spi device from probe() function into static
variable and than tried to use it later (in proc/sysfs), but I get
exceptions.
I am not going to use this method anyway, yet I am curious why it doesn't work.

Thank you,
Ran

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You were actually Right... That's exactly what I wanted :) , so I
probably will  try to use your simple method.
I think that for production , spidev shows a good example how to use
spi as a char device:
https://github.com/Xilinx/linux-xlnx/blob/master/drivers/spi/spidev.c

Thanks!
Ran

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Regards,
Joel

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thanks,

greg k-h