LS1028GPIO初始化为高电平&添加按键

以将GPIO3_DAT14初始化为高电平为例，默认是将用作SPI3_SCK，需要将其先复用为GPIO
修改RCW：firmware/rcw/ls1028ardb/R_SQPP_0x85bb/rcw_1500_gpu600.rcw

SPI3_PMUX=1

在uboot源码中进行初始化
修改位置：packages/firmware/OK1028-linux-uboot/board/freescale/ls1028a/ls1028a.c
定义一个常量

给其赋值，含义：将GPIO3_DAT14设置为输出，值设置为1（高电平）

单独编译firmware固件烧写，一上电用万用表进行测量，可以看到该引脚为高电平（1.8V）

将GPIO3_DAT14进行初始化为高电平，一共32位将第十四位置为1

首先要找到按键使用的GPIO，然后再设备树里面进行设备节点的注册这里以GPIO3_13、GPIO3_16为例，板子上默认是将其用作SPI_SIN、SPI_SOUT。

RCW路径：firmware/rcw/ls1028ardb/R_SQPP_0x85bb/rcw_1500_gpu600.rcw

--- a/packages/firmware/rcw/ls1028ardb/R_SQPP_0x85bb/rcw_1500_gpu600.rcw
+++ b/packages/firmware/rcw/ls1028ardb/R_SQPP_0x85bb/rcw_1500_gpu600.rcw
@@ -28,7 +28,7 @@ IIC3_PMUX=2
 IIC4_PMUX=2
 IIC5_PMUX=1
 IIC6_PMUX=0
-SPI3_PMUX=0
+SPI3_PMUX=1
 CLK_OUT_PMUX=2
 EC1_SAI4_5_PMUX=2
 EC1_SAI3_6_PMUX=1

设备树路径：OK1028-linux-fs/packages/linux/linux/arch/arm64/boot/dts/freescale/OK1028A-C.dts
修改设备树

--- a/packages/linux/OK1028-linux-kernel/arch/arm64/boot/dts/freescale/OK1028A-C.dts
+++ b/packages/linux/OK1028-linux-kernel/arch/arm64/boot/dts/freescale/OK1028A-C.dts
@@ -131,7 +131,23 @@
                default-brightness-level = <200>;
                status = "okay";
        };
-
+       
+       gpio-keys {
+            compatible = "gpio-keys";
+            autorepeat;
+
+                        down {
+                                label = "GPIO Key DOWN";
+                                linux,code = <108>;
+                                gpios = <&gpio3 13 0>;
+                        };
+                        
+     
+       }；
 };

修改完成后全编译生成镜像，烧写完成后，进行验证

root@forlinx:~# cat /sys/kernel/debug/gpio
gpiochip2: GPIOs 416-447, parent: platform/2320000.gpio, 2320000.gpio:
 gpio-429 (                    |GPIO Key DOWN       ) in  hi ACTIVE LOW

gpiochip1: GPIOs 448-479, parent: platform/2310000.gpio, 2310000.gpio:
 gpio-454 (                    |?                   ) out lo

gpiochip0: GPIOs 480-511, parent: platform/2300000.gpio, 2300000.gpio:

关于gpio-keys设备节点的注册可以参考：OK1028-linux-fs/packages/linux/linux/Documentation/devicetree/bindings/input/gpio-keys.txt

参数说明

ompatible = "gpio-keys"        <-------------------------匹配驱动
Label = "GPIO Key UP";         <-------------------------按键标签
linux,code = <103>;           <-------------------------键值 
gpios = <&gpio3 13 0>;         <-------------------------使用gpio3_13，低电平有效 

按键驱动路径：OK1028-linux-kernel/drivers/input/keyboard/gpio_keys.c
按键键值定义：OK1028-linux-kernel/include/uapi/linux/input-event-codes.h