SPI devices not appearing in /dev

[cobey]

Hello,
I am not seeing "spi0.0" and/or "spi0.1" in the "/dev" directory after loading the SPI modules. From lsmod, I see:

Code: Select all

# lsmod
Module                  Size  Used by    Tainted: G
spidev                  4936  0
spi_bcm2708             4589  0

However, "ls /dev" does not list any spi devices. I'm running linux version rpi-3.8.y (3.8.13) for use with xenomai patch. Any help would be most appreciated.

Thanks,
Cobey

[DougieLawson]

There was an old firmware bug that caused this.

sudo apt-get install rpi-update
sudo rpi-update
sudo reboot

Should fix it.

[cobey]

DougieLawson,
Thanks for the reply. Good to know about the old firmware bug. I just did a rebuild using the latest rpi-firmware and userland, but SPI is still not showing up in /dev.

-Cobey

[FLYFISH TECHNOLOGIES]

Hi,

SPI is still not showing up in /dev.

Have you enabled SPI ?

If not, then:

Code: Select all

sudo nano /etc/modprobe.d/raspi-blacklist.conf

Comment-out (add '#') in line:

Code: Select all

#blacklist spi-bcm2708

.. and reboot.


Best wishes, Ivan Zilic.

[cobey]

Hi Ivan,
Thanks for the advice.

Have you enabled SPI ?

Yes, I believe so. I don't see "raspi-blacklist.config" file and I am able to load "spi-bcm2708" and "spidev" modules.

Thanks,
Cobey

[Richard-TX]

if you do a lsmod you should have something like this:

Code: Select all

# lsmod
Module                  Size  Used by
ecb                     1856  0
md4                     3355  0
nls_utf8                1216  1
cifs                  270720  2
i2c_bcm2708             3759  0
i2c_dev                 5620  0
snd_bcm2835            15846  0
snd_pcm                77560  1 snd_bcm2835
snd_seq                53329  0
snd_timer              19998  2 snd_pcm,snd_seq
snd_seq_device          6438  1 snd_seq
snd                    58447  5 snd_bcm2835,snd_timer,snd_pcm,snd_seq,snd_seq_device
snd_page_alloc          5145  1 snd_pcm
spidev                  5224  0
leds_gpio               2235  0
led_class               3562  1 leds_gpio
spi_bcm2708             4510  0

do this

ls -l /etc/modprobe.d/raspi-blacklist.conf

the spi device should be commented out.

then
cat /etc/modules

/etc/modules should contain the line
spi-bcm2708

[cobey]

Hi Richard,
If I load "spi_bcm2708" and "spidev" with modprobe, they do show up in the lsmod output (see original post). The kernel modules are present, but located in /sys/module :

Code: Select all

# find / -name "spi*"
/sys/bus/spi
/sys/bus/spi/drivers/spidev
/sys/devices/platform/bcm2708_spi.0/spi_master
/sys/devices/platform/bcm2708_spi.0/spi_master/spi0
/sys/class/spi_master
/sys/class/spi_master/spi0
/sys/class/spidev
/sys/module/spi_bcm2708
/sys/module/spidev
/sys/module/spidev/drivers/spi:spidev
/lib/modules/3.8.13/kernel/drivers/spi
/lib/modules/3.8.13/kernel/drivers/spi/spidev.ko
/lib/modules/3.8.13/kernel/drivers/spi/spi-bcm2708.ko
/lib/modules/3.8.13-ipipe/kernel/drivers/spi
/lib/modules/3.8.13-ipipe/kernel/drivers/spi/spidev.ko
/lib/modules/3.8.13-ipipe/kernel/drivers/spi/spi-bcm2708.ko

I didn't see a folder named "modprobe.d" anywhere on the system. I also did a search for any files who's name contains "blacklist" and got nothing. Will SPI work if the blacklist file is not present?

Thanks,
Cobey

[cobey]

I discovered that for whatever reason, dynamic loading of spidev module (using modprobe) is broken in rpi-3.8.y kernel. SPI will only work if spidev is statically built into the kernel. This is not the case with other kernel versions I tried, but to get xenomai real-time patch installed I am restricted to kernel 3.8.13. Using "make linux-xconfig", I set CONFIG_SPI_SPIDEV = y and CONFIG_SPI_BCM2708 = y. spidev0.0 and spidev0.1 now show up in /dev after boot.