odroidXu4 GPIO

</pre>             <span >Odroid-XU4/3<span >提供</span><span >1</span><span >個</span><span >30</span><span >針的雙排擴展頭“</span><span >CON10</span><span >”。下面是對這些擴展引腳的說明。在擴展報頭的所有信號都只是</span><span >PWRON</span><span >信號</span><span >1.8V</span></span><span ><span >。 <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 ><span ></span></span></p><p><span >    如上圖，擴展的引腳功能分別有<span >ADC</span><span >、</span><span >UART</span><span >、</span><span >SPI</span><span >、</span><span >I2C</span><span >、</span><span >GPIO</span><span >，每個</span><span >gpio</span><span >都會有相應的擴展號在內核中標識，所以對</span><span >GPIO </span><span >的自定義設置都是通過它這個擴展號去標識。</span></span></p><p><span ><span >    </span></span></p><p><span >     對於<span >GPIO</span><span >驅動的開發在官網</span><span >WIKI</span><span >中只介紹了上圖中擴展引腳和擴展號，經過筆者不斷地搜素尋找，終於在它的內核裡面找到相應的</span><span >GPIO</span><span >驅動。在</span><span >ioboard-keyled.c</span><span >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

以上是它對GPIO引腳擴展號的聲明。

static struct {
	int		gpio_index;		// Control Index
	int 	gpio;			// GPIO Number
	char	*name;			// GPIO Name == sysfs attr name (must)
	bool 	output;			// 1 = Output, 0 = Input
	int 	value;			// Default Value(only for output)
	int		pud;			// 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	},
};

這是GPIO的結構體聲明gpio_index是一個枚舉的標識，gpio是該GPIO對應的擴展號，name及是一個名字，output是對該引腳設置輸入還是輸出，

value是設置輸出的情況下的值，0還是1

此外該文件代碼裡的探測函數ioboard_keyled_probe對引腳作了相應的初始化設置，主體代碼如下：

// Control GPIO Init
	for (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);
				else							gpio_direction_input	(sControlGpios[i].gpio);
	
				s3c_gpio_setpull		(sControlGpios[i].gpio, sControlGpios[i].pud);
			}
		}
	}

代碼中還有設置gpio的函數，都很簡單，就不做詳細介紹，代碼如下所示：

static 	ssize_t set_gpio		(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
    unsigned int	val, 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));
				else
					printk("This GPIO Configuration is INPUT!!\n");
			    return count;
			}
		}
	}

	printk("%s[%d] : undefined gpio!\n", __func__,__LINE__);
    return 	count;
}

通過以上內核的代碼，我們就可以模仿的寫我們自己的GPIO驅動了，我們只需要知道我們所要設置的GPIO的擴展號即可，不需要對設備樹等做什麼更改。