AM3354: Multiple CS support for SPI

Neel Oza

Part Number: AM3354

Hi,

I would like to add multiple CS (Chip Select) support in the device tree to handle multiple SPI devices with help of /dev/spidev1.x (x is a number of CS) nodes. Please find below snippet of my device tree.

   spi1_pins: pinmux_spi1_pins {
      pinctrl-single,pins = <
         0x190 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_aclkx.spi1_sclk */
         0x194 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_fsx.spi1_d0 */
         0x198 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_axr0.spi1_d1 */
         0x19C (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_ahclkr.spi1_cs0 */
         0x108 (MUX_MODE7)  /* mii1_col.gpio3_0 */
      >;
   };

&spi1 {
   status = "okay";
   pinctrl-names = "default";
   pinctrl-0 = <&spi1_pins>;
   ti,pindir-d0-out-d1-in = <1>;
 
   spidev@0 {
      compatible = "linux,spidev";
      spi-max-frequency = <20000000>;
      reg = <0>;
   };

   spidev@1 {
      compatible = "linux,spidev";
      spi-max-frequency = <20000000>;
      reg = <1>;
   };
};

With the mentioned device tree information, I am only able to handle spidev1.0 with the CS0 pin. I am not able to handle spidev1.1 with the CS1 pin. Kindly help me to resolve this issue.

Best Regards,

Neel

over 5 years ago

0 Pavel Botev over 5 years ago

TI__Guru**** 170625 points

Hi Neel,

Seems that spi1_cs1 pinmux is missing from your DTS file. You also need to add #address-cells and #size-cells in spidev nodes. Also "rohm,dh2228fv" should be used instead of "linux,spidev". Please refer pointers for reference:

linux-4.19.38/arch/arm/boot/dts/am335x-boneblack-spi0.dtsi

linux-4.19.38/arch/arm/boot/dts/am335x-icev2-common.dtsi

Regards,
Pavel

0 Neel Oza over 5 years ago in reply to Pavel Botev

Prodigy 90 points

Hi Pavel,

Thank you for your response. But I was not able to solve this issue with the below device tree. Here, I am using gpio3_0 for CS with MUX_MODE7 (I/O). I am not using an internal CS pin with MUX_MODE3. Please let me know what I have done wrong.

spi1_pins: pinmux_spi1_pins {
   pinctrl-single,pins = <
      0x190 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_aclkx.spi1_sclk */
      0x194 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_fsx.spi1_d0 */
      0x198 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_axr0.spi1_d1 */
      0x19C (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_ahclkr.spi1_cs0 */
      0x108 (MUX_MODE7)  /* mii1_col.gpio3_0 */
   >;
};

&spi1 {
   status = "okay";
   pinctrl-names = "default";
   pinctrl-0 = <&spi1_pins>;
   ti,pindir-d0-out-d1-in = <1>;
   ti,spi-num-cs = <2>;

   spidev@0 {
      compatible = "rohm,dh2228fv";
      spi-max-frequency = <20000000>;
      reg = <0>;
      status = "okay";
      #address-cells = <1>;
      #size-cells = <0>;
   };

   spidev@1 {
      compatible = "rohm,dh2228fv";
      spi-max-frequency = <20000000>;
      reg = <1>;
      status = "okay";
      #address-cells = <1>;
      #size-cells = <0>;
   };
};

I have made some corrections in my device-tree and able to resolve my issue with the below device tree.

spi1_pins: pinmux_spi1_pins {
   pinctrl-single,pins = <
      0x190 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_aclkx.spi1_sclk */
      0x194 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_fsx.spi1_d0 */
      0x198 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_axr0.spi1_d1 */
   >;
};

&spi1 {
   status = "okay";
   pinctrl-names = "default";
   pinctrl-0 = <&spi1_pins>;
   ti,pindir-d0-out-d1-in = <1>;
   num_cs = <2>;
   cs-gpios = <&gpio3 17 0>,<&gpio3 0 0>;

   spidev@0 {
      compatible = "rohm,dh2228fv";
      spi-max-frequency = <20000000>;
      reg = <0>;
   };

   spidev@1 {
      compatible = "rohm,dh2228fv";
      spi-max-frequency = <20000000>;
      reg = <1>;
   };
};

0 Pavel Botev over 5 years ago in reply to Neel Oza

TI__Guru**** 170625 points

Neel Oza said:

&spi1 {

   status = "okay";

   pinctrl-names = "default";

   pinctrl-0 = <&spi1_pins>;

   ti,pindir-d0-out-d1-in = <1>;

   ti,spi-num-cs = <2>;

ti,spi-num-cs entry is NOT needed, as already defined in the base AM33xx DTS file, that you need to include in your main DTS file.

linux-kernel/arch/arm/boot/dts/am33xx.dtsi

Neel Oza said:

spi1_pins: pinmux_spi1_pins {

   pinctrl-single,pins = <

      0x190 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_aclkx.spi1_sclk */

      0x194 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_fsx.spi1_d0 */

      0x198 (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_axr0.spi1_d1 */

      0x19C (PIN_INPUT_PULLUP | MUX_MODE3) /* mcasp0_ahclkr.spi1_cs0 */

      0x108 (MUX_MODE7) /* mii1_col.gpio3_0 */

   >;

};

One CS is McSPI pin, other is GPIO pin. That might be the main issue. In your working setup, you have CS both GPIO pins.

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AM3354: Multiple CS support for SPI