Changes between Version 17 and Version 18 of SPI

Timestamp:

11/16/2021 05:37:33 PM (4 years ago)

Author:

Tim Harvey

Comment:

added additional board examples for spidev dt configuration

SPI

@@ -169 +169 @@
 Userspace access to SPI devices is done through the /dev/spidev<bus>.<chip-select> device interface. In order to use this you must have spidev enabled in the kernel (CONFIG_SPI_SPIDEV) and have a spidev node defined under the SPI controller in the device-tree.
 
-In order to support {{{spidev}}} a spidev child node needs to be present in the device-tree under the SPI host controller. For example, a GW54xx which brings out the ecspi2 host interface:
+In order to support {{{spidev}}} a spidev child node needs to be present in the device-tree under the SPI host controller.
+
+Examples:
+ * Venice:
+  - GW71xx (imx8mm-venice-gw71xx.dtsi), GW72xx (imx8mm-venice-gw72xx.dtsi), and GW73xx (imx8mm-venice-gw73xx.dtsi) all provide ecspi2 to an off-board connector with GPIO5_IO13 as a chip select:
+{{{#!c
+/* off-board header */
+&ecspi2 {
+        pinctrl-names = "default";
+        pinctrl-0 = <&pinctrl_spi2>;
+        cs-gpios = <&gpio5 13 GPIO_ACTIVE_LOW>;
+        status = "okay";
+
+        /*
+         * SPI_CS0 goes to the off-board connector
+         * compatible must match a string from drivers/spi/spidev.c's compatible list
+         */
+        spidev0: spidev0@0 {
+                compatible = "rohm,dh2228fv";
+                reg = <0>;
+                spi-max-frequency = <10000000>;
+        };
+};
+}}}
+ * Newport:
+  - GW620x/GW630x/GW640x which has a single SPI controller with 2 chip selects, with CS0 going to an off-board connector and CS1 used for a CAN controller (loaded on GW6204/GW6304/GW6404 boards). Change dts/gw620x-linux.dtsi, dts/gw630x-linux.dtsi dts/gw640x-linux.dtsi to:
+{{{#!c
+&spi_7_0 {
+        /*
+         * SPI_CS0 goes to the off-board connector
+         * compatible must match a string from drivers/spi/spidev.c's compatible list
+         */
+        spidev0: spidev0@0 {
+                compatible = "rohm,dh2228fv";
+                reg = <0>;
+                spi-max-frequency = <10000000>;
+        };
+
+        /*
+         * SPI_CS1 goes to the Microchip MCP2515 CAN controller (GW6204/GW6304/GW6404)
+         */
+        can0: can@1 {
+                compatible = "microchip,mcp2515","linux,spidev";
+                reg = <1>;
+                clocks = <&can20m>;
+                oscillator-frequency = <20000000>;
+                interrupt-parent = <&gpio_6_0>;
+                interrupts = <5 0x8>; /* IRQ_TYPE_LEVEL_LOW */
+                spi-max-frequency = <10000000>;
+        };
+};
+}}}
+  - GW610x which has a single SPI controller with 2 chip selects, with CS0 going to an off-board connector. Change dts/gw610x-linux.dtsi to add the following at the end:
+{{{#!c
+&spi_7_0 {
+        /*
+         * SPI_CS0 goes to the off-board connector
+         * compatible must match a string from drivers/spi/spidev.c's compatible list
+         */
+        spidev0: spidev0@0 {
+                compatible = "rohm,dh2228fv";
+                reg = <0>;
+                spi-max-frequency = <10000000>;
+        };
+};
+}}}
+ * Ventana:
+  - GW54xx (arch/arm/boot/dts/imx6qdl-gw52xx.dtsi) which brings out the ecspi2 host interface to an off-board connector with GPIO2_IO26 as a chip select:
 {{{#!c
 &ecspi2 {
@@ -184 +251 @@
 };
 }}}
+  - GW52xx (arch/arm/boot/dts/imx6qdl-gw53xx.dtsi) which brings out the ecspi3 host interface to an off-board connector with GPIO4_IO24 as a chip select:
+{{{#!c
+&ecspi3 {
+        cs-gpios = <&gpio4 24 GPIO_ACTIVE_HIGH>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&pinctrl_ecspi3>;
+        status = "okay";
+
+        spidev0: spidev@0 {
+                compatible = "rohm,dh2228fv";
+                reg = <0>;
+                spi-max-frequency = <60000000>;
+        };
+};
+}}}
+
+In the above examples, adjust 'spi-max-frequency' according to the max frequency your slave device can support.
 
 For instructions on compiling and updating a device-tree see [wiki:linux/devicetree linux/devicetree]