[RK3288][Android6.0] 調試筆記 --- 通用GPIO驅動控制LED【轉】

本文轉載自：http://m.blog.csdn.net/kris_fei/article/details/69553422

Platform: ROCKCHIP
OS: Android 6.0
Kernel: 3.10.92

由於板子沒有lcd無法得知sd卡升級是否完成,因此使用LED顯示.
Recovery中升級完成后控制GPIO輸出高電平點亮LED.

系統自帶GPIO控制驅動:
內核已經自帶了通用GPIO驅動,可以直接在用戶空間操作.
路徑: /sys/class/gpio
root@rk3288:/sys/class/gpio # ls
export
gpiochip0
gpiochip120
gpiochip152
gpiochip184
gpiochip216
gpiochip24
gpiochip248
gpiochip280
gpiochip56
gpiochip88
unexport

比如我要操作GPIO8_A6作為高電平輸出有效, 那么有以下問題:
1. 對應的gpio number是多少呢?
2. 如何設置成輸出
3. 如何輸出高電平

問題1:
可以通過/sys/kernel/debug/gpio查詢信息:
root@rk3288:/sys/kernel/debug # cat gpio                                       
//snip
GPIOs 184-215, platform/ff770000.pinctrl, gpio6:
 gpio-193 (?                   ) in  hi
 gpio-194 (?                   ) in  hi

GPIOs 216-247, platform/ff770000.pinctrl, gpio7:
 gpio-218 (enable              ) out hi
 gpio-219 (lcd_en              ) in  hi
 gpio-220 (lcd_cs              ) in  hi
 gpio-221 (gslX680 wake pin    ) out hi
 gpio-222 (gslX680 irq pin     ) out lo
 gpio-223 (headset_gpio        ) in  hi
 gpio-233 (?                   ) in  hi
 gpio-234 (?                   ) in  hi

GPIOs 248-279, platform/ff770000.pinctrl, gpio8:

GPIOs 280-311, platform/ff770000.pinctrl, gpio15:

可以看到gpio8是以nubmer為248開始, 那么GPIO8_A6就是 248 +　6 = 254
接下來就可以導出gpio了
root@rk3288:/sys/class/gpio # echo 254 > export                          
root@rk3288:/sys/class/gpio # ls
export
gpio254
......

問題2
root@rk3288:/sys/class/gpio/gpio254 # echo out > direction                     
root@rk3288:/sys/class/gpio/gpio254 # cat direction                            
out

問題3:
root@rk3288:/sys/class/gpio/gpio254 # echo 1 > value                           
root@rk3288:/sys/class/gpio/gpio254 # cat value                                
1

解決方法:
init.rc
[kris@:~/rk3288/device/rockchip/common/recovery/etc]$ g df
diff --git a/recovery/etc/init.rc b/recovery/etc/init.rc
index efe2a5d..75d7554 100755
--- a/recovery/etc/init.rc
+++ b/recovery/etc/init.rc
@@ -85,6 +85,12 @@ on late-init
 on property:sys.powerctl=*
    powerctl ${sys.powerctl}
 
+#Kris, 170407, GPIO8_A6 -> gpio254, used to inform sd upgrade complete.
+on property:sdupgrade.complete=true
+       write /sys/class/gpio/export 254
+       write /sys/class/gpio/gpio254/direction out
+       write /sys/class/gpio/gpio254/value 1
+
 service ueventd /sbin/ueventd
     critical
     seclabel u:r:ueventd:s0

recovery.cpp
[kris@:~/rk3288/bootable/recovery]$ g df
diff --git a/recovery.cpp b/recovery.cpp
index 8299672..a0edc15 100755
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -2285,6 +2285,10 @@ HANDLE_STATUS :
         strcat(kernellogPath, "/kernel.txt");
         save_kernel_log(kernellogPath);
         #endif
+
+       //Kris, 170407, light led on after sd upgrade complete.
+       property_set("sdupgrade.complete", "true");
+
                if (bSDMounted)
             checkSDRemoved();


參考:
http://blog.csdn.net/cjsycyl/article/details/46310939