root@arria10:~# find /sys/ -name 'spi*'

/sys/kernel/debug/clk/spi_m_clk
/sys/kernel/debug/tracing/events/spi
/sys/kernel/debug/tracing/events/spi/spi_controller_idle
/sys/kernel/debug/tracing/events/spi/spi_controller_busy
/sys/kernel/debug/tracing/events/spi/spi_message_submit
/sys/kernel/debug/tracing/events/spi/spi_message_start
/sys/kernel/debug/tracing/events/spi/spi_message_done
/sys/kernel/debug/tracing/events/spi/spi_transfer_start
/sys/kernel/debug/tracing/events/spi/spi_transfer_stop
/sys/kernel/debug/regmap/spi0.0
/sys/devices/platform/soc/ffda5000.spi/spi_master
/sys/devices/platform/soc/ffda5000.spi/spi_master/spi0
/sys/devices/platform/soc/ffda5000.spi/spi_master/spi0/spi0.0
/sys/devices/platform/soc/ffda5000.spi/spi_master/spi0/spi0.0/statistics/spi_sync
/sys/devices/platform/soc/ffda5000.spi/spi_master/spi0/spi0.0/statistics/spi_async
/sys/devices/platform/soc/ffda5000.spi/spi_master/spi0/spi0.0/statistics/spi_sync_immediate
/sys/devices/platform/soc/ffda5000.spi/spi_master/spi0/statistics/spi_sync
/sys/devices/platform/soc/ffda5000.spi/spi_master/spi0/statistics/spi_async
/sys/devices/platform/soc/ffda5000.spi/spi_master/spi0/statistics/spi_sync_immediate
/sys/class/spidev
/sys/class/spi_master
/sys/class/spi_master/spi0
/sys/firmware/devicetree/base/__symbols__/spi2
/sys/firmware/devicetree/base/__symbols__/spi0
/sys/firmware/devicetree/base/__symbols__/spin_ctrl_1
/sys/firmware/devicetree/base/__symbols__/spi_m_clk
/sys/firmware/devicetree/base/__symbols__/spi1
/sys/firmware/devicetree/base/__symbols__/spin_ctrl_2
/sys/firmware/devicetree/base/soc/spi@ff809000
/sys/firmware/devicetree/base/soc/spi@ffda5000
/sys/firmware/devicetree/base/soc/spi@ffda5000/resource-manager@0/spi-max-frequency
/sys/firmware/devicetree/base/soc/clkmgr@ffd04000/clocks/spi_m_clk
/sys/firmware/devicetree/base/soc/spi@ffda4000
/sys/firmware/devicetree/base/spi@0xc00c0800
/sys/firmware/devicetree/base/spi@0xc00c0800/spidev@0
/sys/firmware/devicetree/base/spi@0xc00c0800/spidev@0/spi-max-frequency
/sys/firmware/devicetree/base/testcase-data-2/fairway-1/ride@200/spin-controller
/sys/firmware/devicetree/base/testcase-data-2/fairway-1/ride@200/spin-rph
/sys/firmware/devicetree/base/testcase-data-2/fairway-1/ride@100/spin-controller
/sys/firmware/devicetree/base/testcase-data-2/fairway-1/ride@100/spin-controller-names
/sys/firmware/devicetree/base/testcase-data-2/substation@100/motor-1/spin
/sys/bus/platform/drivers/spi_altera
/sys/bus/spi
/sys/bus/spi/devices/spi0.0
/sys/bus/spi/drivers/spi-nor
/sys/bus/spi/drivers/altr_a10sr/spi0.0
/sys/bus/spi/drivers/spidev
/sys/module/spidev
/sys/module/spidev/drivers/spi:spidev
/sys/module/spi_altera

On 2021-03-18 03:44, Zoran wrote:

I am guessing here.... But what do you have while executing the
following command being in /sys
as root?

root@arm:/sys# find . -name spi*

Zee
_______

On Wed, Mar 17, 2021 at 5:41 PM jchludzinski via
lists.yoctoproject.org
<jchludzinski=vivaldi.net@...> wrote:

In the YOCTO/Linux source tree there's drivers/spi/ which has all
the source for SPI drivers. There's only 1 file, spidev.c, which
has:

static int __init spidev_init(void)
{
int status;

/* Claim our 256 reserved device numbers.  Then register a
class
* that will key udev/mdev to add/remove /dev nodes.
Last, register
* the driver which manages those device numbers.
*/
BUILD_BUG_ON(N_SPI_MINORS > 256);
status = register_chrdev(SPIDEV_MAJOR, "spi",
&spidev_fops);
if (status < 0)
return status;

spidev_class = class_create(THIS_MODULE, "spidev");
if (IS_ERR(spidev_class)) {
unregister_chrdev(SPIDEV_MAJOR,
spidev_spi_driver.driver.name);
return PTR_ERR(spidev_class);
}

status = spi_register_driver(&spidev_spi_driver);
if (status < 0) {
class_destroy(spidev_class);
unregister_chrdev(SPIDEV_MAJOR,
spidev_spi_driver.driver.name);
}
return status;
}
module_init(spidev_init);

... for creating device files in udev.

So when I use 'make nconfig' to specifiy that I want a loadable
module for the ALTERA SPI driver, why don't I see a spidev.o file
in drivers/spi/ ?

How does spi-altera.ko create device files without a call to
register_chrdev(...).

How is it a loadable module without module_init(...)?

When I separately build spidev.c as an .ko and try loading it, I
get: "Device or resourse busy"

---John

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