Re: [PATCH v5 7/7] dts: ti: k3-am625-beagleplay: Add mikroBUS

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On 6/27/24 22:37, Andrew Davis wrote:
On 6/27/24 11:26 AM, Ayush Singh wrote:
DONOTMERGE

Add mikroBUS connector and some mikroBUS boards support for Beagleplay.
The mikroBUS boards node should probably be moved to a more appropriate
location but I am not quite sure where it should go since it is not
dependent on specific arch.

Signed-off-by: Ayush Singh <ayush@xxxxxxxxxxxxxxx>
---
  arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts | 94 +++++++++++++++++++++++---
  1 file changed, 86 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts b/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts
index 70de288d728e..3f3cd70345c4 100644
--- a/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts
+++ b/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts
@@ -38,6 +38,7 @@ aliases {
          serial2 = &main_uart0;
          usb0 = &usb0;
          usb1 = &usb1;
+        mikrobus0 = &mikrobus0;
      };
        chosen {
@@ -227,6 +228,56 @@ simple-audio-card,codec {
          };
      };
  +    mikrobus0: mikrobus-connector {
+        compatible = "mikrobus-connector";
+        pinctrl-names = "default", "pwm_default", "pwm_gpio",
+                "uart_default", "uart_gpio", "i2c_default",
+                "i2c_gpio", "spi_default", "spi_gpio";
+        pinctrl-0 = <&mikrobus_gpio_pins_default>;
+        pinctrl-1 = <&mikrobus_pwm_pins_default>;
+        pinctrl-2 = <&mikrobus_pwm_pins_gpio>;
+        pinctrl-3 = <&mikrobus_uart_pins_default>;
+        pinctrl-4 = <&mikrobus_uart_pins_gpio>;
+        pinctrl-5 = <&mikrobus_i2c_pins_default>;
+        pinctrl-6 = <&mikrobus_i2c_pins_gpio>;
+        pinctrl-7 = <&mikrobus_spi_pins_default>;
+        pinctrl-8 = <&mikrobus_spi_pins_gpio>;
+
+        mikrobus-gpio-names = "pwm", "int", "rx", "tx", "scl", "sda",
+                      "mosi", "miso", "sck", "cs", "rst", "an";
+        mikrobus-gpios = <&main_gpio1 11 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 9 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 24 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 25 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 22 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 23 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 7 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 8 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 14 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 13 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 12 GPIO_ACTIVE_HIGH>,
+                 <&main_gpio1 10 GPIO_ACTIVE_HIGH>;
+
+        spi-controller = <&main_spi2>;
+        spi-cs = <0>;
+        spi-cs-names = "default";
+
+        board = <&lsm6dsl_click>;
+    };
+
+    mikrobus_boards {
+        thermo_click: thermo-click {
+            compatible = "maxim,max31855k", "mikrobus-spi";

I might be missing something, but your solution cannot possibly be
to list every click board that could be connected (all 1500+ of them)
to every mikroBUS connector on every device's DT file..


I think you missed something. `mikrobus-boards` is not a child node of `mikrobus0`. See the `board` property in `mikrobus0`. That is what selects the board attached to the connector.

The `mikcrobus-boards` node itself should be moved to some independent location and included from a system that wants to support mikrobus boards. The connector will only have a phandle to the board (or boards in case a single mikroBUS board has 1 i2c and 1 spi sensor or some combination).



Each click board should have a single DTSO overlay file to describe the
click board, one per click board total. And then that overlay should
apply cleanly to any device that has a mikroBUS interface.


Yes, that is the goal.



Which means you have not completely solved the fundamental problem of
abstracting the mikroBUS connector in DT. Each of these click device child
nodes has to be under the parent connector node. Which means a phandle
to the parent node, which is not generically named. For instance
if my board has 2 connectors, I would have mikrobus0 and mikrobus1,
the click board's overlay would look like this:

/dts-v1/;
/plugin/;

&mikrobus0 {
    status = "okay";

    mikrobus_board {
        thermo-click {
            compatible = "maxim,max31855k", "mikrobus-spi";
            spi-max-frequency = <1000000>;
            pinctrl-apply = "spi_default";
        };
    };
};


No, it will look as follows:

```

&mikrobus0 {
    status = "okay";

    board = <&thermo-click>;

};


&mikrobus_board {
        thermo-click {
            compatible = "maxim,max31855k", "mikrobus-spi";
            spi-max-frequency = <1000000>;
            pinctrl-apply = "spi_default";
        };
  };

```



I think this solution is almost there, but once you solve the above
issue, we could just apply the right overlay for our attached click
board ahead of time and not need the mikroBUS bus driver at all.


Well, the driver is still needed because some things cannot be done generically in dt. Eg:

1. SPI chipselect. Each connector will have different chipselect number mapped to CS pin. In fact a mikrobus board might use other pins like RST as chipselect as well.

2. Using pins other than their intended purpose like GPIO.



Andrew

+            spi-max-frequency = <1000000>;
+            pinctrl-apply = "spi_default";
+        };
+
+        lsm6dsl_click: lsm6dsl-click {
+            compatible = "st,lsm6ds3", "mikrobus-spi";
+            spi-max-frequency = <1000000>;
+            pinctrl-apply = "spi_default";
+        };
+    };
  };
    &main_pmx0 {
@@ -387,6 +438,18 @@ AM62X_IOPAD(0x01f0, PIN_OUTPUT, 5) /* (A18) EXT_REFCLK1.CLKOUT0 */
          >;
      };
  +    mikrobus_pwm_pins_default: mikrobus-pwm-default-pins {
+        pinctrl-single,pins = <
+            AM62X_IOPAD(0x01a4, PIN_INPUT, 2) /* (B20) MCASP0_ACLKX.ECAP2_IN_APWM_OUT */
+        >;
+    };
+
+    mikrobus_pwm_pins_gpio: mikrobus-pwm-gpio-pins {
+        pinctrl-single,pins = <
+            AM62X_IOPAD(0x01a4, PIN_INPUT, 7) /* (B20) MCASP0_ACLKX.GPIO1_11 */
+        >;
+    };
+
      mikrobus_i2c_pins_default: mikrobus-i2c-default-pins {
          pinctrl-single,pins = <
              AM62X_IOPAD(0x01d0, PIN_INPUT_PULLUP, 2) /* (A15) UART0_CTSn.I2C3_SCL */ @@ -394,6 +457,13 @@ AM62X_IOPAD(0x01d4, PIN_INPUT_PULLUP, 2) /* (B15) UART0_RTSn.I2C3_SDA */
          >;
      };
  +    mikrobus_i2c_pins_gpio: mikrobus-i2c-gpio-pins {
+        pinctrl-single,pins = <
+            AM62X_IOPAD(0x01d0, PIN_INPUT, 7) /* (A15) UART0_CTSn.GPIO1_22 */ +            AM62X_IOPAD(0x01d4, PIN_INPUT, 7) /* (B15) UART0_RTSn.GPIO1_23 */
+        >;
+    };
+
      mikrobus_uart_pins_default: mikrobus-uart-default-pins {
          pinctrl-single,pins = <
              AM62X_IOPAD(0x01d8, PIN_INPUT, 1) /* (C15) MCAN0_TX.UART5_RXD */ @@ -401,6 +471,13 @@ AM62X_IOPAD(0x01dc, PIN_OUTPUT, 1) /* (E15) MCAN0_RX.UART5_TXD */
          >;
      };
  +    mikrobus_uart_pins_gpio: mikrobus-uart-gpio-pins {
+        pinctrl-single,pins = <
+            AM62X_IOPAD(0x01d8, PIN_INPUT, 7) /* (C15) MCAN0_TX.GPIO1_24 */ +            AM62X_IOPAD(0x01dc, PIN_INPUT, 7) /* (E15) MCAN0_RX.GPIO1_25 */
+        >;
+    };
+
      mikrobus_spi_pins_default: mikrobus-spi-default-pins {
          pinctrl-single,pins = <
              AM62X_IOPAD(0x01b0, PIN_INPUT, 1) /* (A20) MCASP0_ACLKR.SPI2_CLK */ @@ -410,6 +487,15 @@ AM62X_IOPAD(0x0198, PIN_INPUT, 1) /* (A19) MCASP0_AXR2.SPI2_D1 */
          >;
      };
  +    mikrobus_spi_pins_gpio: mikrobus-spi-gpio-pins {
+        pinctrl-single,pins = <
+            AM62X_IOPAD(0x0194, PIN_INPUT, 7) /* (B19) MCASP0_AXR3.GPIO1_7 */ +            AM62X_IOPAD(0x0198, PIN_INPUT, 7) /* (A19) MCASP0_AXR2.GPIO1_8 */ +            AM62X_IOPAD(0x01ac, PIN_INPUT, 7) /* (E19) MCASP0_AFSR.GPIO1_13 */ +            AM62X_IOPAD(0x01b0, PIN_INPUT, 7) /* (A20) MCASP0_ACLKR.GPIO1_14 */
+        >;
+    };
+
      mikrobus_gpio_pins_default: mikrobus-gpio-default-pins {
          bootph-all;
          pinctrl-single,pins = <
@@ -630,8 +716,6 @@ &main_gpio0 {
    &main_gpio1 {
      bootph-all;
-    pinctrl-names = "default";
-    pinctrl-0 = <&mikrobus_gpio_pins_default>;
      gpio-line-names = "", "", "", "", "",            /* 0-4 */
          "SPE_RSTN", "SPE_INTN", "MIKROBUS_GPIO1_7",    /* 5-7 */
          "MIKROBUS_GPIO1_8", "MIKROBUS_GPIO1_9",        /* 8-9 */
@@ -804,15 +888,11 @@ it66121_out: endpoint {
  };
    &main_i2c3 {
-    pinctrl-names = "default";
-    pinctrl-0 = <&mikrobus_i2c_pins_default>;
      clock-frequency = <400000>;
      status = "okay";
  };
    &main_spi2 {
-    pinctrl-names = "default";
-    pinctrl-0 = <&mikrobus_spi_pins_default>;
      status = "okay";
  };
  @@ -876,8 +956,6 @@ &main_uart1 {
  };
    &main_uart5 {
-    pinctrl-names = "default";
-    pinctrl-0 = <&mikrobus_uart_pins_default>;
      status = "okay";
  };


Ayush Singh





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