Having trouble binding a SPI driver on the BeagleBone Black. The driver in question, ltc2947-spi, is in the linux mainline, but not in the beaglebone kernel tree. When I get this working, I'll submit a PR to add it.
I compiled the ltc2947 drivers as an out-of-tree module using this repo (also on github).
% sudo apt-get install linux-headers-$(uname -r)
% find /lib/modules/$(uname -r) -iname "*ltc29*"
% make
The module compiles fine, and modinfo produces the expected output:
% sudo modinfo ltc2947-spi.ko
filename: /home/lily/kmod-ltc2947/ltc2947-spi.ko
license: GPL
description: LTC2947 SPI power and energy monitor driver
author: Nuno Sa <nuno.sa@analog.com>
alias: spi:ltc2947
depends: ltc2947-core
name: ltc2947_spi
vermagic: 5.4.70-ti-r19 SMP preempt mod_unload modversions ARMv7 p2v8
And insmod appears to insert the module correctly (note there are two modules, since the SPI and I2C drivers for this chip share a common core):
% sudo insmod ./ltc2947-core.ko && sudo insmod ./ltc2947-spi.ko
% grep ltc2947 /proc/modules
ltc2947_spi 16384 0 - Live 0x00000000 (O)
ltc2947_core 24576 1 ltc2947_spi, Live 0x00000000 (O)
% tree /sys/bus/spi/drivers/ltc2947
/sys/bus/spi/drivers/ltc2947
├── bind
├── module -> ../../../../module/ltc2947_spi
├── uevent
└── unbind
1 directory, 3 files
From here, I need to bind the driver to a device on the SPI bus. I'm using the Mikroe VCP Monitor 3 Click connected to SPI via the mikroBus Cape. The board is in slot 1 right now, so the pin connections are:
- P9_28: CS
- P9_29: MISO
- P9_30: MOSI
- P9_31: SCK
It is not yet clear to me where I specify the chip select pin, or how to determine the string to echo to /sys/bus/usb/drivers/ltc2947/bind.
The pins from the cape correspond to spi1, according to this diagram:
and I noticed spi1 was already bound to spidev, so I unbind it:
% echo "spi1.0" | sudo tee -a /sys/bus/spi/drivers/spidev/unbind
spi1.0
% echo "spi1.1" | sudo tee -a /sys/bus/spi/drivers/spidev/unbind
spi1.1
% tree /sys/bus/spi/drivers/spidev
/sys/bus/spi/drivers/spidev
├── bind
├── module -> ../../../../module/spidev
├── spi0.0 -> ../../../../devices/platform/ocp/48000000.interconnect/48000000.interconnect:segment@0/48030000.target-module/48030000.spi/spi_master/spi0/spi0.0
├── spi0.1 -> ../../../../devices/platform/ocp/48000000.interconnect/48000000.interconnect:segment@0/48030000.target-module/48030000.spi/spi_master/spi0/spi0.1
├── uevent
└── unbind
3 directories, 3 files
But then when I try to bind it to the ltc2947 driver, it gives the error "/sys/bus/spi/drivers/ltc2947/bind: No such device":
% echo "spi1" | sudo tee -a /sys/bus/spi/drivers/ltc2947/bind
spi1
tee: /sys/bus/spi/drivers/ltc2947/bind: No such device
% echo "spi1.0" | sudo tee -a /sys/bus/spi/drivers/ltc2947/bind
spi1.0
tee: /sys/bus/spi/drivers/ltc2947/bind: No such device
% echo "spi1.1" | sudo tee -a /sys/bus/spi/drivers/ltc2947/bind
spi1.1
tee: /sys/bus/spi/drivers/ltc2947/bind: No such device
Echoing to the bind under /sys/module produces the same result:
% echo "spi1" | sudo tee -a /sys/module/ltc2947_spi/drivers/spi:ltc2947/bind
spi1
tee: '/sys/module/ltc2947_spi/drivers/spi:ltc2947/bind': No such device
