[参考译文] SK-AM62A-LP：[SDK 10.00.00]分配给 MOSI 和 MISO 的 SPI D0和 D1引脚

尊敬的 Ramy：

Unknown 说：

关于 SPI 从器件、我得到官方不支持、但您是否有关于 SPI 作为从器件运行需要进行哪些更改的指南/手册/步骤？

本质上、您需要将与 DMA 相关的属性(dmas和dma-names)添加到设备树节点、然后也添加 spi-slave到 SPI 外围设备树节点、如下所示：

$ git show
commit 30253dd73e444c451cf352b2b005d32e03b080be (HEAD -> ti-linux-6.6.y-spi-slave-dev)
Author: Andreas Dannenberg <dannenberg@ti.com>
Date:   Wed Nov 13 15:15:04 2024 -0600

    arm64: dts: ti: k3-am62a: Configure SPI0 as Slave-Mode spidev Device

    Note that the SPI Slave in Linux doesn’t implement flow-control by default
    and custom flow control mechanism need to be implemented according to the
    application for deterministic performance.

    Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>

diff --git a/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts b/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts
index 3047586a6d9d..b582f08d1fe1 100644
--- a/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts
+++ b/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts
@@ -451,6 +451,15 @@ AM62AX_IOPAD(0x028, PIN_INPUT, 0) /* (J22) OSPI0_D7 */
                        AM62AX_IOPAD(0x008, PIN_INPUT, 0) /* (J24) OSPI0_DQS */
                >;
        };
+
+       main_spi0_pins_default: main-spi-pins-default {
+               pinctrl-single,pins = <
+                       AM62AX_IOPAD(0x01bc, PIN_INPUT, 0) /* (A17) SPI0_CLK */
+                       AM62AX_IOPAD(0x01b4, PIN_INPUT, 0) /* (D16) SPI0_CS0 */
+                       AM62AX_IOPAD(0x01c0, PIN_INPUT, 0) /* (B15) SPI0_D0 */
+                       AM62AX_IOPAD(0x01c4, PIN_INPUT, 0) /* (E15) SPI0_D1 */
+               >;
+       };
 };

 &mcu_pmx0 {
@@ -944,3 +953,25 @@ partition@7fc0000 {
                };
        };
 };
+
+&main_spi0 {
+               status = "okay";
+               #address-cells = <0>;
+               #size-cells = <0>;
+               pinctrl-names = "default";
+               pinctrl-0 = <&main_spi0_pins_default>;
+               ti,pindir-d0-out-d1-in = <1>;
+               spi-slave;
+               dmas = <&main_pktdma 0xc300 0>, <&main_pktdma 0x4300 0>;
+               dma-names = "tx0", "rx0";
+
+               slave {
+                               /*
+                                * Using spidev compatible is warned loudly,
+                                * thus use another equivalent compatible id
+                                * from spidev.
+                                */
+                               compatible = "rohm,dh2228fv";
+                               spi-max-frequency = <24000000>;
+               };
+};

然后、当您引导时、您可以在此处找到从设备：

root@am62axx-evm:/opt/edgeai-gst-apps# ls -al /dev/spi*
crw------- 1 root root 153, 0 Jan  1 00:00 /dev/spidev1.0

root@am62axx-evm:/opt/edgeai-gst-apps# ls -al /sys/class/spi_slave/
total 0
drwxr-xr-x  2 root root 0 Jan  1 00:08 .
drwxr-xr-x 81 root root 0 Jan  1 00:08 ..
lrwxrwxrwx  1 root root 0 Jan  1 00:08 spi1 -> ../../devices/platform/bus@f0000/20100000.spi/spi_slave/spi1

然后,你应该能够尝试它像这样使用spidev_test. 在本例中、它会挂起、因为我没有任何东西在数据中计时...

root@am62axx-evm:/opt/edgeai-gst-apps# ./spidev_test -D /dev/spidev1.0 -v -p "12345678"
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 kHz)

以下是一些适用的 E2E 主题以及其他可能有用的信息：

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1262607/am3351-linux-support-for-spi-as-a-slave-device/4780250

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1301459/tda4al-q1-regarding-mcu-spi-slave-mode-configuration-issues

如果您能让它发挥作用、请告诉我；如果您能分享您的发现、这对每个人都很有帮助。

谢谢、Andreas