How to enable spidev on i.MX6 using kernel 3.10.9?

[rathben]

Hi,

I'm moving my i.MX6 based project from LTIB to Yocto and trying to reproduce the steps I used in LTIB to enable spidev on a particular SPI. This is described well in a number of places including here https://community.freescale.com/thread/302612

This mostly amounts to modifying some files in /arch/arm/mach-mx6, however this directory and the applicable sources don't exist in the 3.10.9 kernel. I have successfully done this with Yocto+3.0.35, but have an interest in using a newer kernel.

Is there a new way to perform this sort of hardware configuration? If so, can someone provide me with a pointer to some information?

Thanks! -Ben

[niklasmolin]

Hi Ben.

Did you manage to solve this problem?

Did you manage to figure out how the GPIO works for the SS pins?

I'm still a little bit confused how the pin is configured to be that specific GPIO (I couldn't find the GPIO in any of the IOMUX settings)?

Also when I try to enable multiple spi busses, I only get one spi device driver in my /dev directory.

Have you managed to do this?

Thanks,

Niklas

[rathben]

Hi Niklas,

Yes, I did get multiple busses working. I added something like this to my .dts file:

&ecspi2 {

  fsl,spi-num-chipselects = <2>;

  cs-gpios = <&gpio3 19 0>,<0>;

  pinctrl-names = "default";

  pinctrl-0 = <&pinctrl_ecspi2_1>;

  status = "okay";

    spidev@0x00 {

        compatible = "spidev";

        spi-max-frequency = <20000000>;

        reg = <0>;

    };

    spidev@0x01 {

        compatible = "spidev";

        spi-max-frequency = <20000000>;

        reg = <1>;

    };

};

&iomuxc {

...

...

    ecspi2 {

      pinctrl_ecspi2_1: ecspi2grp-1 {

            fsl,pins = <

                MX6SL_PAD_LCD_DAT10__ECSPI2_MISO 0x100b1

                MX6SL_PAD_LCD_DAT9__ECSPI2_MOSI 0x100b1

                MX6SL_PAD_LCD_DAT8__ECSPI2_SCLK 0x100b1

                MX6SL_PAD_HSIC_STROBE__GPIO3_IO20 0x100b1

                MX6SL_PAD_LCD_DAT11__ECSPI2_SS1 0x100b1

            >;

      };

    };

If you have still have problems getting GPIOs working, try the patch mentioned in this thread: Problems modifying device tree to blink an LED

[carlosgallegos]

Hi,

I have already modified the imx6sl-evk.dts file and I added the following code:

&ecspi2 {

  fsl,spi-num-chipselects = <2>;

  cs-gpios = <0>,<&gpio3 31 0>;

  pinctrl-names = "default";

  pinctrl-0 = <&pinctrl_ecspi2_1>;

  status = "okay";

   spidev@0x00 {

   compatible = "spidev";

   spi-max-frequency = <20000000>;

   reg = <0>;

   };

   spidev@0x01 {

   compatible = "spidev";

   spi-max-frequency = <20000000>;

   reg = <1>;

   };

};

&iomuxc {

...

...

   ecspi2 {

   pinctrl_ecspi2_1: ecspi2grp-1 {

   fsl,pins = <

   MX6SL_PAD_ECSPI2_MISO__ECSPI2_MISO 0x100b1

   MX6SL_PAD_ECSPI2_MOSI__ECSPI2_MOSI 0x100b1

   MX6SL_PAD_ECSPI2_SCLK__ECSPI2_SCLK 0x100b1

   MX6SL_PAD_ECSPI2_SS0__ECSPI2_SS0 0x100b1

   MX6SL_PAD_KEY_ROW3__GPIO3_IO31 0x100b1

   >;

   };

   };

And I can see /dev/spidev32765. 0 and /dev/spidev32765.1. With this I hope I can use the SPI2 that is in the LCD port (I have an adapter for this), but I cannot even see the clock when something is sent (or at least I assume that). The test I am doing is based on a program from the kernel files and you can find it in the reference [1].

References:

[1] spidev_test.c - The Linux Kernel Archives

[carlosgallegos]

Hi Ben,

I have started working with the SPI of the imx6slevk, so i'm extremely new at this. I have already modified the file imx6sl-evk.dts and I was expecting that after the reboot the device would appear under /dev/. Can you give me some advice at what should I do next, I am so lost at this. (sorry for my english).

[saurabh206]

Hi,

Jose

Have you enabled CONFIG_SPI_SPIDEV=y in defconfig file?

Best Regards,

Saurabh

[carlosgallegos]

Hi Saurabh,

I went and edit the file /usr/src/kernel/arch/arm/configs/imx_v7_defconfig and added the line that you show me. Then I reboot the imx6 and still nothing in /dev. I forgot to mention and I don't know if it is important but I am working in L3.10.17.

Greetings,

JC.

[saurabh206]

Hi,

JC

L3.10.17 process is same.

just make sure that your CONFIG_SPI_SPIDEV=7 is there in .config file.

Saurabh

[carlosgallegos]

Hi Saurabh,

I already modify my .config under /usr/src/kernel, but I still can see any spider under /dev. I don't know if i'm editing the wrong file under ../dts, I modified the file called imx6sl-evk.dts and added the code that was posted before. Also were can I find the pin nomenclature for the imx6slevk, maybe I am not writing the correct pin name.

[niklasmolin]

Hi Ben.

Thanks for your response.

I managed to enable 2 chip selects on one SPI bus.

But when I add another SPI bus, then it won't show up in my /dev.

&ecspi1 {

  fsl,spi-num-chipselects = <2>;

  cs-gpios = <&gpio4 9 0>, <&gpio5 9 0>;

  pinctrl-names = "default";

  pinctrl-0 = <&pinctrl_ecspi1_2>;

  status = "okay";

        chip1: spidev@0 {

               compatible = "spidev";

               spi-max-frequency = <20000000>;

               reg = <0>;

        };

        chip2: spidev@1 {

               compatible = "spidev";

               spi-max-frequency = <20000000>;

               reg = <1>;

        };

};

&ecspi3 {

  fsl,spi-num-chipselects = <1>;

  cs-gpios = <&gpio4 24 0>;

  pinctrl-names = "default";

  pinctrl-0 = <&pinctrl_ecspi3_1>;

  status = "okay";

        chip3: spidev@0 {

               compatible = "spidev";

               spi-max-frequency = <20000000>;

               reg = <0>;

        };

};

All I see in my /dev are from ecspi1.

/Niklas

[rathben]

No, sorry I didn't try that yet.

[niklasmolin]

Hi Ben.

I'm still working on this problem.

Another quick question.

I'm a little bit confused how to know which GPIO that should be sued for the select?

I saw in your example that to iomuxed:

                MX6SL_PAD_HSIC_STROBE__GPIO3_IO20 0x100b1

                MX6SL_PAD_LCD_DAT11__ECSPI2_SS1 0x100b1

and then for cs used, gpio3 19

Best regards,

Niklas

[rathben]

I use both. The <0> in cs-gpios definition means select the "native" chip select

[niklasmolin]

Hi Ben.

Managed to get it to work.

Seems like I already had the right GPIO pin, but but connected to the wrong SS (first SS should be unconnected).

What I suspect with the multiple SPI busses, is that it gives them the same name.

For instance I have ecspi1 and ecspi3 and using spidev.

When I look in the /dev directory I get /dev/spi32766.0 (and spi32766.1 if I use multiple SS)

But it seems like it doesn't include the spi bus number in the name.

When I look at www.kernel.org/doc/Documentation/spi/spidev it should include B.C in the name, which it doesn't do in this case.

So I think that's why I "only" see one SPI bus (meaning ecspi interface number).

I'll continue to investigate this thing.

/Niklas

[rathben]

this topic is discussed a little here: https://community.freescale.com/thread/319336

[AnsonHuang · Accepted solution]

Hi, Ben

     New kernel of L3.10 uses device tree, all those hardware related config will be passed from dtb to kernel, you can refer to arch/arm/boot/dts/imx6q.dtsi, arch/arm/boot/dts/imx6qdl.dtsi and arch/arm/boot/dts/imx6qdl-sabresd.dtsi's ecspi node. grep spi in these three files to see how device tree works.