what is the difference between "spi_master" and "spidev" on AM335x EVM?

Shannon,

My understanding is that you want to change your board file in the kernel to add a spidev device.  Then you will get a spidev device node.  There have been some beaglebone based patches for this at https://groups.google.com/forum/#!topic/beagleboard/B3akyoyjwG4 and http://arago-project.org/git/?p=meta-ti.git;a=blob;f=recipes-kernel/linux/linux-ti33x-psp-3.2/beaglebone/0040-beaglebone-export-SPI2-as-spidev-when-no-capes-are-u.patch;h=4a004d7a407779334e8bef4fe7b73e583eb394bc;hb=d33058225df1156174db1131d964de1ef0ab3b48 which may help guide you.

Chase

Hi Shannon,

Does your problem solved? How? I meet the same trouble with you ?

Please help,thanks!

Chase,

Thanks for your contribution.  I overlooked your response until now.  But, I got it working, as noted later in this thread.

Shannon

Additionally, to clarify the original question of my thread...

"am335x_spi0_slave_info[]" is just a name, having no real master/slave characteristics.

I wasn't seeing the spi clock signal (as a master would provide) until I changed the pinmux for the signal to

"{"spi0_sclk.spi0_sclk", OMAP_MUX_MODE0 | AM33XX_PIN_OUTPUT | AM33XX_PULL_UP | AM33XX_PULL_ENBL},"

I'd welcome better info that others may be able to contribute.

Hi shannon,

According to your guidance, I change  the corresponding  position  of kernel:

root@am335x-evm:/sys# find /sys/ -name '*spi*'
./sys/devices/platform/omap/omap2_mcspi.1
./sys/devices/platform/omap/omap2_mcspi.1/spi_master
./sys/devices/platform/omap/omap2_mcspi.1/spi_master/spi1
./sys/devices/platform/omap/omap2_mcspi.1/spi1.0
./sys/devices/platform/omap/omap2_mcspi.2
./sys/devices/platform/omap/omap2_mcspi.2/spi_master
./sys/devices/platform/omap/omap2_mcspi.2/spi_master/spi2
./sys/bus/platform/devices/omap2_mcspi.1
./sys/bus/platform/devices/omap2_mcspi.2
./sys/bus/platform/drivers/omap2_mcspi
./sys/bus/platform/drivers/omap2_mcspi/omap2_mcspi.1
./sys/bus/platform/drivers/omap2_mcspi/omap2_mcspi.2
./sys/bus/spi
./sys/bus/spi/devices/spi1.0
./sys/class/spi_master
./sys/class/spi_master/spi1
./sys/class/spi_master/spi2

but during test procedure, appear the following questions:

root@am335x-evm:/opt# ./spidev_test -D /sys/bus/spi/devices/spi1.0
can't open device: Is a directory
Aborted
root@am335x-evm:/opt# ./spidev_test -D /sys/devices/platform/omap/omap2_mcspi.1/spi1.0
can't open device: Is a directory
Aborted

Do you  meet this problem?

The compilation of the SPI driver is according to http://processors.wiki.ti.com/index.php/AM335x_McSPI_Driver%27s_Guide:

Building into Kernel

  Device Drivers  ---> 
         [*] SPI support  ---> 
            <*>   McSPI driver for OMAP

• Enable W25Q64 SPI flash support. This step is mandatory if for using root file-system on SPI flash.

Device Drivers  ---> 
  <*> Memory Technology Device (MTD) support  ---> 
         Self-contained MTD device drivers  ---> 
            <*> Support most SPI Flash chips (AT26DF, M25P, W25X, ...)
            [*]   Use FAST_READ OPCode allowing SPI CLK <= 50MHz (NEW)

Is this process right?

thank you,Looking forward to your help！

I don't recall if I hit that specific problem, but I did discover that I didn't understand the situation clearly enough to get creative with the naming of anything.  I kept every "spidev" part as "spidev".  I see that yours is coming out as just ..."spi"1.0. 

Also, spidev_test is to be run against /dev/spidev#.#, where is appears as a read/write file.  Don't run the test to the nodes under /sys/...  Until you see the node under /dev/... the implementation isn't complete.

Additionally, I disabled the SPI flash memory support.  I don't know how that impacts what you're trying to do.

I'm not real clear on the whole situation myself.  I only indicated what I did to make /dev/spidev work for my situation.  I'd hope a more knowledgeable person would contribute.

Hi shannon,

 I also want to find spidev in the /dev directory, I had a lot of trying to  achieve it, but have no success.

I don't know the problem is the driver code, or drive compiled process, it makes me very confused.

Anyway, thank you all the same!

Hi all !!

I have recognized the same problems ( same board and same sdk version ) .

in the file board-am335xevm.c  inside /home/sitara/board-support/linux-3.2-psp04.06.00.07.sdk/arch/arm/mach-omap2  , the settings for the spi seem to be similar to yours,

specially in

static struct spi_board_info am335x_spi0_slave_info[] = {
    {
        .modalias      = "m25p80",
        .platform_data = &am335x_spi_flash,
        .irq           = -1,
        .max_speed_hz  = 24000000,
        .bus_num       = 1,
        .chip_select   = 0,
    },
};

static struct spi_board_info am335x_spi1_slave_info[] = {
    {
        .modalias      = "m25p80",
        .platform_data = &am335x_spi_flash,
        .irq           = -1,
        .max_speed_hz  = 12000000,
        .bus_num       = 2,
        .chip_select   = 0,
    },
};

with the exeption of modalias and platform data. the name "m25p80" instead of "spidev" couldn't be a big problem. About . platform_data?! I still need to compile kernel?

Thanks in advance and sorry form my bad english! :P

Marco

Marco,

As I noted earlier, keeping the name "spidev" is important.  Now I understand better, that the Linux driver that exports this to for filesystem access - /dev/spidev - needs this .modalias to be "spidev".

I think.  In any case, it didn't work for me until I changed the .modalias back to "spidev"

good luck.

Shannon

Thanks a lot Shannon! :)

Forgive me for my trivial question , I'm a total beginner on this world ;)

Now, i'm looking for the painful job: re-compile (cross compile) arago linux kernel! I hope to come back alive :D

Best regards

Marco