本文记录如何在Android和linux上操作GPIO 。

1 前置条件

ROM必须满足以下条件：

* Android M     >= V170603
* Android N     >= V170421
* Ubuntu Server >= V180712
* Ubuntu Mate   >= V180531

2、如何获取GPIO编号

可以从GPIO Bank或 Pins 获取GPIO编号。 不同版本的内核将有所不同。

• Linux 3.14 (Android M, N and Ubuntu)

Banks:

# cat /sys/kernel/debug/pinctrl/c1109880.pinmux/gpio-rangesGPIO ranges handled:
0: banks GPIOS   [155 - 255] PINS [10 - 110]
0: ao-bank GPIOS [145 - 154] PINS [ 0 -   9]Notice: ao-bank means GPIOAO_X gpios

Pins:

# cat /sys/kernel/debug/pinctrl/c1109880.pinmux/pins
...
pin 5 (GPIOAO_5) 
pin 6 (GPIOAO_6) 
...
pin 28 (GPIOH_2) 
pin 29 (GPIOH_3) 
pin 30 (GPIOH_4) 
pin 31 (GPIOH_5) 
pin 32 (GPIOH_6) 
pin 33 (GPIOH_7) 
pin 34 (GPIOH_8) 
pin 35 (GPIOH_9) 
...

例如，获取GPIOH_4，GPIOH_5和GPIOAO_6的编号。

Number(GPIOH_5)  = bank + pin = 155 - 10 + 31 = 176
Number(GPIOH_4)  = bank + pin = 155 - 10 + 30 = 175
Number(GPIOAO_6) = bank + pin = 145 -  0 +  6 = 151

• Linux 4.9 (Android O and Ubuntu)

aobus-banks:
Banks:

root@Khadas:~# cat /sys/kernel/debug/pinctrl/pinctrl@14/gpio-ranges 
GPIO ranges handled:
0: aobus-banks GPIOS [0 - 10] PINS [0 - 10]

Pins:

root@Khadas:~# cat /sys/kernel/debug/pinctrl/pinctrl@14/pins 
registered pins: 11
pin 0 (GPIOAO_0)  pinctrl@14
pin 1 (GPIOAO_1)  pinctrl@14
pin 2 (GPIOAO_2)  pinctrl@14
pin 3 (GPIOAO_3)  pinctrl@14
pin 4 (GPIOAO_4)  pinctrl@14
pin 5 (GPIOAO_5)  pinctrl@14
pin 6 (GPIOAO_6)  pinctrl@14
pin 7 (GPIOAO_7)  pinctrl@14
pin 8 (GPIOAO_8)  pinctrl@14
pin 9 (GPIOAO_9)  pinctrl@14
pin 10 (GPIO_TEST_N)  pinctrl@14

例如，获取 GPIOAO_6 的编号：

Number(GPIOAO_6) = bank + pin = 0 - 0 + 6 = 6

periphs-banks:
Banks:

root@Khadas:~# cat /sys/kernel/debug/pinctrl/pinctrl@4b0/gpio-ranges
GPIO ranges handled:
0: periphs-banks GPIOS [11 - 110] PINS [11 - 110]

Pins:

root@Khadas:~# cat /sys/kernel/debug/pinctrl/pinctrl@4b0/pins 
registered pins: 100
pin 11 (GPIOZ_0)  pinctrl@4b0
pin 12 (GPIOZ_1)  pinctrl@4b0
pin 13 (GPIOZ_2)  pinctrl@4b0
...
pin 27 (GPIOH_0)  pinctrl@4b0
pin 28 (GPIOH_1)  pinctrl@4b0
pin 29 (GPIOH_2)  pinctrl@4b0
pin 30 (GPIOH_3)  pinctrl@4b0
pin 31 (GPIOH_4)  pinctrl@4b0
pin 32 (GPIOH_5)  pinctrl@4b0
pin 33 (GPIOH_6)  pinctrl@4b0
pin 34 (GPIOH_7)  pinctrl@4b0
pin 35 (GPIOH_8)  pinctrl@4b0
pin 36 (GPIOH_9)  pinctrl@4b0
...
pin 81 (GPIODV_21)  pinctrl@4b0
pin 82 (GPIODV_22)  pinctrl@4b0
pin 83 (GPIODV_23)  pinctrl@4b0
pin 84 (GPIODV_24)  pinctrl@4b0
...

例如，获取GPIOH_5的编号:
Number(GPIOH_5) = bank + pin = 11 - 11 + 32 = 32

2.1 Android

GPIO List

PIN         GPIO         Number
PIN37       GPIOH5       176
PIN33       GPIOAO6      151

有两种访问GPIO的方法：

• ADB 命令
• 第三方应用

ADB 命令

连接 adb:

$ adb connect IP_ADDR 

登录 VIMs:

$ adb shell

获取root权限

$ su

获取 gpio(GPIOH5)

$ echo 176  > /sys/class/gpio/export

配置 gpio(GPIOH5) 为 output

$ echo out > /sys/class/gpio/gpio176/direction

将gpio（GPIO 5）配置为高电平输出

$ echo 1 >  /sys/class/gpio/gpio176/value

将gpio（GPIO 5）配置为低电平输出

$ echo 0 >  /sys/class/gpio/gpio176/value

将gpio（GPIO 5）配置为输入

$ echo in > /sys/class/gpio/gpio176/direction

获取gpio（GPIOH5）level

$ cat /sys/class/gpio/gpio176/value

Release gpio(GPIOH5)

$ echo 176 > /sys/class/gpio/unexport

第三方应用

获取root权限

Process mProcess = Runtime.getRuntime().exec("su");

获取 gpio(GPIOH5)

DataOutputStream os = new DataOutputStream(mProcess.getOutputStream());
os.writeBytes("echo " + 176 + " > /sys/class/gpio/export\n");

将gpio（GPIO 5）配置为高电平输出

os.writeBytes("echo out > /sys/class/gpio/gpio" + 176 + "/direction\n");
os.writeBytes("echo 1 > /sys/class/gpio/gpio" + 176 + "/value\n");

将gpio（GPIO 5）配置为输入

os.writeBytes("echo in > /sys/class/gpio/gpio" + 176 + "/direction\n");

获取gpio（GPIOH5）level

Runtime runtime = Runtime.getRuntime(); 
Process process = runtime.exec("cat " + "/sys/class/gpio/gpio" + 176 + "/value");  
InputStream is = process.getInputStream(); 
InputStreamReader isr = new InputStreamReader(is); 
BufferedReader br = new BufferedReader(isr); 
String line ; 
while (null != (line = br.readLine())) { return Integer.parseInt(line.trim()); 
} 

Release gpio(GPIOH5)

os.writeBytes("echo " + 176 + " > /sys/class/gpio/unexport\n");

2.2 Ubuntu

GPIO 列表

• 列表**-3.14

  PIN         GPIO         Number
  PIN37       GPIOH5         176
  PIN33       GPIOAO6        151
  

• Linux-4.9.40

  PIN         GPIO         Number
  PIN37       GPIOH5         32
  PIN33       GPIOAO6        6
  

**如何在终端上访问GPIO **

[如 linux-3.14]
获取 gpio(GPIOH5)

$ echo 176 > /sys/class/gpio/export

配置 gpio(GPIOH5) 为 output

$ echo out > /sys/class/gpio/gpio176/direction

将gpio（GPIO 5）配置为高电平输出

$ echo 1 >  /sys/class/gpio/gpio176/value

将gpio（GPIO 5）配置为低电平输出

$ echo 0 >  /sys/class/gpio/gpio176/value

将gpio（GPIO 5）配置为输入

$ echo in > /sys/class/gpio/gpio176/direction

获取 level gpio(GPIOH5)

$ cat  /sys/class/gpio/gpio176/value

Release gpio(GPIOH5)

$ echo 176 > /sys/class/gpio/unexport