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pio:?pinctrl@01c20800?{
???compatible?=?"allwinner,sun50i-pinctrl";
???reg?=?<0x0?0x01c20800?0x0?0x400>;
???interrupts?=?<0?11?4>,
?????????<0?17?4>,
?????????<0?21?4>;
???device_type?=?"pio";
???clocks?=?<&clk_pio>;
???gpio-controller;
???interrupt-controller;
???#interrupt-cells?=?<2>;
???#size-cells?=?<0>;
???#gpio-cells?=?<6>;???

r_pio:?pinctrl@01f02c00?{
???compatible?=?"allwinner,sun50i-r-pinctrl";
???reg?=?<0x0?0x01f02c00?0x0?0x400>;
???interrupts?=?<0?45?4>;
???clocks?=?<&clk_cpurpio>;
???device_type?=?"r_pio";

???gpio-controller;
???interrupt-controller;
???#interrupt-cells?=?<2>;
???#size-cells?=?<0>;
???#gpio-cells?=?<6>;

關于設備樹設置GPIO的文檔描述：

其中“?#gpio-cells?＝?<6>”表示在設備樹里描述使用一個gpio口需要提供6個指定的參數(shù).
通過文檔，可以得知6個參數(shù)的分別作用:
gpio?=?<&pio???1???1???1???1???1??0>;
????|??????|????|???|???|???|???|??|-------------------表示有效電平
????|??????|????|???|???|???|???|----------------------上下拉,?0關閉功能,?1上拉,?2下拉,?3保留
????|??????|????|???|???|???|-------------------------驅(qū)動力,電流等級(0?-?3)，級別越高，輸出電流越大
????|??????|????|???|???|----------------------------gpio功能類型,0輸入,?1輸出,?6和外部中斷,7關閉功能(具體查手冊)
????|??????|????|???|------------------------------pin?bank?內(nèi)偏移(即組內(nèi)第幾個io口).
????|??????|????|---------------------------------哪組gpio,?PA(0),PB(1),PC(2),PD(3),PE(4),PF(5),PG(6),PH(7),PI(8),PJ(9),PK(10),PL(11)
????|??????|--------------------------------------指向哪個gpio控制器,??pio?/?r_pio(PL組)
????|-----------------------------------------------------屬性名字(隨便命名)

那么在Linux驅(qū)動里如何獲取設備樹里設備節(jié)點的gpio口信息呢？

#include?

//只需一個函數(shù)即可
int?of_get_named_gpio_flags(struct?device_node?*np,?const?char?*propname,
????int?index,?enum?of_gpio_flags?*flags);

//返回值為int類型的gpio口.
//np為設備或設備子節(jié)點對象,?propname為指定的屬性名字,?index表示獲取屬性里的第幾個值
//?其中flags一定得注意，按文檔里的說明應就是一個int類型的值，但根本就不能為int參數(shù)(會導致kernel?panic)，
//?通過閱讀內(nèi)核里的代碼得出，?flags的參數(shù)應為struct?gpio_config類型.?定義在下面文件:
"include/linux/sys_config.h"
struct?gpio_config?{
?????u32?gpio;???????/*?gpio?global?index,?must?be?unique?*/
?????u32?????mul_sel;????/*?multi?sel?val:?0?-?input,?1?-?output...?*/
?????u32?????pull;???????/*?pull?val:?0?-?pull?up/down?disable,?1?-?pull?up...?*/
?????u32?????drv_level;??/*?driver?level?val:?0?-?level?0,?1?-?level?1...?*/
?????u32?data;???????/*?data?val:?0?-?low,?1?-?high,?only?vaild?when?mul_sel?is?input/output?*/
?};

獲取到int類型的gpio口后，就可以使用linux/gpio.h里的gpio口操作函數(shù):

#include??//里面聲明io口的操作函數(shù)

int?gpio_request(unsigned?gpio,?const?char?*label);//每個io只能被請求一次,可防止多個驅(qū)動來控制同一個IO口
void?gpio_free(unsigned?gpio);?//釋放已請求的io口

int?gpio_direction_input(unsigned?gpio);?//把指定的IO口作輸入功能,?gpio用于指定具體哪個io口
int?gpio_direction_output(unsigned?gpio,?int?value);?//作輸出功能，并根據(jù)value的值輸出高低電平

int?gpio_get_value(unsigned?gpio);?//獲取指定IO口的電平
void?gpio_set_value(unsigned?gpio,?int?value);?//設置IO口的電平為value(0/1)

int?gpio_to_irq(unsigned?gpio);??//根據(jù)io口，獲取到它對應的中斷號(io口大都有外部中斷功能)

應用例子，如圖板上有兩個led,和一個蜂鳴器:?

jkbuzzer?{
???compatible?=?"jk,buzzer";
???gpios?=?<&pio?3?24?1?1?1?1>;?
?};

?jkleds?{
???compatible?=?"jk,leds";
???gpios?=?<&r_pio?11?10?1?1?1?1>,?<&r_pio?11?12?1?1?1?1>;
?};

#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?

int?myprobe(struct?platform_device?*pdev)
{
????struct?device_node?*nd?=?pdev->dev.of_node;
????int?gpio;???
????struct?gpio_config?config;


????printk("gpio?count:%d\n",?of_gpio_named_count(nd,?"gpios"));
????gpio?=?of_get_named_gpio_flags(nd,?"gpios",?0,?(enum?of_gpio_flags?*)&config);
????if?(!gpio_is_valid(gpio))
????????printk("gpio?isn't?valid\n");
????if?(gpio_request(gpio,?pdev->name)?0)
????????????printk("gpio?request?failed?%d\n",?gpio);

????gpio_direction_output(gpio,?1);
????msleep(3000);
????gpio_direction_input(gpio);
????gpio_free(gpio);
????return?0;
}

int?myremove(struct?platform_device?*pdev)
{
????printk("in?myremove?...\n");
????return?0;
}

struct?of_device_id?ids[]?=?{
????{.compatible?=?"jk,buzzer"},
????{},
};

struct?platform_driver?mydrv?=?{
????.probe?=?myprobe,
????.remove?=?myremove,

????.driver?=?{
????????.owner?=?THIS_MODULE,
????????.name?=?"mydrv"?,

????????.of_match_table?=?ids,
????},
};

module_platform_driver(mydrv);
MODULE_LICENSE("GPL");

#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?

int?myprobe(struct?platform_device?*pdev)
{
????struct?device_node?*nd?=?pdev->dev.of_node;
????int?gpio,?n,?i;?
????struct?gpio_config?config;


????n?=?of_gpio_named_count(nd,?"gpios");
????for?(i?=?0;?i?????{
????????gpio?=?of_get_named_gpio_flags(nd,?"gpios",?i,?(enum?of_gpio_flags?*)&config);
????????if?(!gpio_is_valid(gpio))
????????????printk("gpio?isn't?valid\n");
????????if?(gpio_request(gpio,?pdev->name)?0)
????????????printk("gpio?request?failed?%d\n",?gpio);

????????gpio_direction_output(gpio,?1);
????????msleep(3000);
????????gpio_direction_input(gpio);
????????gpio_free(gpio);
????}
????return?0;
}

int?myremove(struct?platform_device?*pdev)
{
????printk("in?myremove?...\n");
????return?0;
}

struct?of_device_id?ids[]?=?{
????{.compatible?=?"jk,leds"},
????{},
};

struct?platform_driver?mydrv?=?{
????.probe?=?myprobe,
????.remove?=?myremove,

????.driver?=?{
????????.owner?=?THIS_MODULE,
????????.name?=?"mydrv"?,

????????.of_match_table?=?ids,
????},
};