SPI communication on BeagleBone AM335x

enable spidev in the kernel (remember the make in the sdk uses /arch/arm/configs/tisdk_am335x-evm-defconfig when built in the sdk root) and modify  linuxkernelpsp/arch/arm/mach-omap2/board-am335xevm.c:

search for vm_dev_cfg beaglebone_dev_cfg and add {spi1_init, DEV_ON_BASEBOARD, PROFILE_ALL}, to the struct.

search for spi_board_info am335x_spi1_slave_info and replace the default "m25p80" protocol manager, have it point to spidev instead.

static struct spi_board_info am335x_spi1_slave_info[] = {
	{
		.modalias      = "spidev",
		.platform_data = &am335x_spi_flash,
		.irq           = -1,
		.max_speed_hz  = 10000000,
		.bus_num       = 2,
		.chip_select   = 0,
		.mode = SPI_MODE_0,
	},
};

compile the kernel and when you boot up on it you should see /dev/spidev2.0

There's a few examples using this in user mode....

http://www.haifux.org/lectures/258/gpio_spi_i2c_userspace.pdf

That has a pretty short example in it.  There are some pretty good ones right in the kernel/Documents/spi/ folder.

Hi,

How to enable the spidev in kernel ?

i use command "make menuconfig" in linux kernel path, then i go to "spi support", and enable "User mode SPI device driver support" , then i type "make" to build uImage. but i found that the "User mode SPI device driver support" will disable itself after i build uImage. did i miss something?

Thanks.

In the root of the sdk (not the linux psp), the make file hides a lot of whats going on; it'll use the config file "tisdk_am335x-evm-defconfig".  you can manually edit that file or copy your config file back to where that file is stored after you menuconfig it (in linuxpsp)...  (its stored in linuxkernelpsp/arch/arm/configs/tisdk_am335x-evm-defconfig )  --or just go to the SPI module directory and edit the make file there (add it with a config option already defined).

I had successfully made these changes using the 5.03.02 version of the SDK.

After migrating to the 5.04 version, this no longer works.

Any suggestions?

I haven't upgraded the SDK yet, was thinking of waiting until 5.04.01 (apr 16?).

Thanks dal.

I'm confused. Was there a change to the v5.04 SDK that makes the previously described changes ineffective?

I believe I have re-incorporated those changes to the new SDK and the spidev-2.0 device is not instantiated after booting.

Update,

Not sure why (make clean, maybe) but now I'm able to re-create the previously described update and spidev-2.0 is available and working.

Thanks again.

good news.

BTW, just so if there's any question about this in future (I know the write up is pretty terse above)  -- I came across this on the beagle list a couple of days ago.

http://communistcode.co.uk/blog/blogPost.php?blogPostID=1

This is a pretty decent write up on how to get SPIDEV to work.

-Dal

Hi everyone,

How to make the spi0 work on beaglebone?

My kernel is 'linux-3.1.0-psp04.06.00.03.sdk', The SPI driver is from the kernel .The config of the SPI is according to  http://processors.wiki.ti.com/index.php/AM335x_McSPI_Driver%27s_Guide 。

According to the links  provided by Dal http://communistcode.co.uk/blog/blogPost.php?blogPostID=1 ,I  modify  the kernel ，but I have  troubles below:

root@am335x-evm:/# ls /dev/spidev*  

ls: /dev/spidev*: No such file or directory

……

I found the document of Dal provided is different from  my system. My system  should be the same with Keldy, and did somebody spi0 can work? How?

Hi dal :

I do everything as you mentioned but I can not see /dev/spidev2.0 in my file system.

I use am335x evm and kernel version is 3.2.0, I do not know if it is device tree issue.

Could you give me some suggestions?

Best regards,

Marcus 

Some possible errors:

1) spidev not enabled in kernel.  view .config and verify that the spidev option has =y
2) In board___.c, struct spi_board_info modalias should only be "spidev", not "spidev1" or "spidev2.0"
3) In board___.c, struct spi_board_info is not initialized via spi_register_board_info()
4) In board___.c, spi pin mux not configured

Hi Argeebee :

I appreciate your reply!

According your suggestion, I have found out the reason why I can not see spidev.

Thanks a lot!

Best regards,

Marcus

Hi Sinisa :

I do not remember the reason, but I sure it should be related with the link below.

http://e2e.ti.com/support/arm/sitara_arm/f/791/t/168122

Best regards

Marcus