odroidXu4 GPIO

来源：互联网发布：java 两个数组值交换编辑：程序博客网时间：2024/06/05 19:45

</pre>             <span style="font-size:18px;">Odroid-XU4/3<span style="font-family:宋体;">提供</span><span style="font-family:Calibri;">1</span><span style="font-family:宋体;">个</span><span style="font-family:Calibri;">30</span><span style="font-family:宋体;">针的双排扩展头“</span><span style="font-family:Calibri;">CON10</span><span style="font-family:宋体;">”。下面是对这些扩展引脚的说明。在扩展报头的所有信号都只是</span><span style="font-family:Calibri;">PWRON</span><span style="font-family:宋体;">信号</span><span style="font-family:Calibri;">1.8V</span></span><span style="font-family:宋体;"><span style="font-size:18px;">。 <img src="http://img.blog.csdn.net/20160515212753850?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" /></span></span></p><p><span style="font-family:宋体;"><span style="font-size:18px;"></span></span></p><p><span style="font-size:18px;">    如上图，扩展的引脚功能分别有<span style="font-family:Calibri;">ADC</span><span style="font-family:宋体;">、</span><span style="font-family:Calibri;">UART</span><span style="font-family:宋体;">、</span><span style="font-family:Calibri;">SPI</span><span style="font-family:宋体;">、</span><span style="font-family:Calibri;">I2C</span><span style="font-family:宋体;">、</span><span style="font-family:Calibri;">GPIO</span><span style="font-family:宋体;">，每个</span><span style="font-family:Calibri;">gpio</span><span style="font-family:宋体;">都会有相应的扩展号在内核中标识，所以对</span><span style="font-family:Calibri;">GPIO </span><span style="font-family:宋体;">的自定义设置都是通过它这个扩展号去标识。</span></span></p><p><span style="font-family:宋体;"><span style="font-size:18px;">    </span></span></p><p><span style="font-size:18px;">     对于<span style="font-family:Calibri;">GPIO</span><span style="font-family:宋体;">驱动的开发在官网</span><span style="font-family:Calibri;">WIKI</span><span style="font-family:宋体;">中只介绍了上图中扩展引脚和扩展号，经过笔者不断地搜素寻找，终于在它的内核里面找到相应的</span><span style="font-family:Calibri;">GPIO</span><span style="font-family:宋体;">驱动。在</span><span style="font-family:Calibri;">ioboard-keyled.c</span><span style="font-family:宋体;">中：</span></span><pre name="code" class="html">// GPIO Export Number define#define GPX2_5_EXPORT_NUM   29#define GPX2_6_EXPORT_NUM   30#define GPX1_6_EXPORT_NUM   22#define GPX1_2_EXPORT_NUM   18#define GPX2_7_EXPORT_NUM   31#define GPX2_4_EXPORT_NUM   28#define GPX1_3_EXPORT_NUM   19#define GPB3_2_EXPORT_NUM   209#define GPX2_0_EXPORT_NUM   24

以上是它对GPIO引脚扩展号的声明。

static struct {intgpio_index;// Control Indexint gpio;// GPIO Numberchar*name;// GPIO Name == sysfs attr name (must)bool output;// 1 = Output, 0 = Inputint value;// Default Value(only for output)intpud;// Pull up/down register setting : S3C_GPIO_PULL_DOWN, UP, NONE} sControlGpios[] = {{IOBOARD_SW1,  GPX2_5_EXPORT_NUM,  "sw1",0,0,S3C_GPIO_PULL_NONE},{IOBOARD_SW2,  GPX2_6_EXPORT_NUM,  "sw2",0,0,S3C_GPIO_PULL_NONE},{IOBOARD_SW3,  GPX1_6_EXPORT_NUM,  "sw3",0,0,S3C_GPIO_PULL_NONE},{IOBOARD_SW4,  GPX1_2_EXPORT_NUM,  "sw4",0,0,S3C_GPIO_PULL_NONE},{IOBOARD_LED1,  GPX2_7_EXPORT_NUM,  "led1",1,0,S3C_GPIO_PULL_NONE},{IOBOARD_LED2,  GPX2_4_EXPORT_NUM,  "led2",1,0,S3C_GPIO_PULL_NONE},{IOBOARD_LED3,  GPX1_3_EXPORT_NUM,  "led3",1,0,S3C_GPIO_PULL_NONE},{IOBOARD_LED4,  GPB3_2_EXPORT_NUM,  "led4",1,0,S3C_GPIO_PULL_NONE},{IOBOARD_LED5,  GPX2_0_EXPORT_NUM,  "led5",1,1,S3C_GPIO_PULL_NONE},};

这是GPIO的结构体声明gpio_index是一个枚举的标识，gpio是该GPIO对应的扩展号，name及是一个名字，output是对该引脚设置输入还是输出，value是设置输出的情况下的值，0还是1

此外该文件代码里的探测函数ioboard_keyled_probe对引脚作了相应的初始化设置，主体代码如下：

// Control GPIO Initfor (i = 0; i < ARRAY_SIZE(sControlGpios); i++) {if(sControlGpios[i].gpio){if(gpio_request(sControlGpios[i].gpio, sControlGpios[i].name)){printk("%s : %s gpio reqest err!\n", __FUNCTION__, sControlGpios[i].name);}else{if(sControlGpios[i].output)gpio_direction_output(sControlGpios[i].gpio, sControlGpios[i].value);elsegpio_direction_input(sControlGpios[i].gpio);s3c_gpio_setpull(sControlGpios[i].gpio, sControlGpios[i].pud);}}}

代码中还有设置gpio的函数，都很简单，就不做详细介绍，代码如下所示：

static ssize_t set_gpio(struct device *dev, struct device_attribute *attr, const char *buf, size_t count){    unsigned intval, i;    if(!(sscanf(buf, "%d\n", &val))) return-EINVAL;for (i = 0; i < ARRAY_SIZE(sControlGpios); i++) {if(sControlGpios[i].gpio){if(!strcmp(sControlGpios[i].name, attr->attr.name)){if(sControlGpios[i].output)    gpio_set_value(sControlGpios[i].gpio, ((val != 0) ? 1 : 0));elseprintk("This GPIO Configuration is INPUT!!\n");    return count;}}}printk("%s[%d] : undefined gpio!\n", __func__,__LINE__);    return count;}

通过以上内核的代码，我们就可以模仿的写我们自己的GPIO驱动了，我们只需要知道我们所要设置的GPIO的扩展号即可，不需要对设备树等做什么更改。

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