cc:NSA - LOL ...

What platform? 

I have very recently been through a long process of getting the spidev working 
on an Emcraft STM-SOM with STM32F4.  The documentation was lacking but once I 
got the right hint from emcraft support I was able to get it going.  I am using 
SPI1 and SPI2 as built in kernel modules.  I am then using ioctl ops on the 
/dev/spidev0.0 and /dev/spidev1.0.   The supported ioctl accesses are defined 
in .../A2F/root/usr/include/linux/spi/spidev.h.

Here is a brief overview of the process:

make kmenuconfig =>  enable spis 
make bmenuconfig =>  enable mdev

In .../linux/arch/arm/mach-stm32/...
iomux.c - configure required port.pins for alternate functions
spi.c - add board info structs for each spidev 

In .../linux/drivers/spi/...
spi_stm32.c - configure spi_cr1 for correct format
spidev.c - instrument as necessary with debug printk's to see progress

I am sure there is some stuff I left out here.  I have a demo spidev project 
from emcraft that uses spi2 and spi5 - if you would like that I can forward it 
to your private email ... I think some of the key ingredients are the 
configurations they used in initramfs, busybox, kernel config, and rc.  These 
are in the demo project also ...

Good luck ...








Date: Tue, 28 Jan 2014 15:45:04 -0800
From: eric.fow...@gmail.com
To: uclinux-dev@uclinux.org
Subject: [uClinux-dev] Accessing SPI

I have an Emcraft distro with a SPI device at /dev/spi. I wish to access the 
device for (for instance) controlling the chip select pin, read, write, etc. 
I have seen a document on controlling a SPI driver on ucLinux from user space 
(http://www.uclinux.org/pub/uClinux/ports/blackfin/docs/pdf-docs/SPI_device_driver.pdf)
 , but it references IOCTLs that are not in my source tree. 

I did find a file, linux/spi/spidev.h, that has a struct defined that seems to 
be used by user mode SPI code, but it is not clear how I am to use it, in 
particular, which IOCTLs are available, and how I can get access to the 
interface at low levels. 

How in general do ucLinux app developers access SPI devices?
Eric
-- 
cc:NSA



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