高通msm8909对gpio的使用（包括pinctrl的功能设置，gpio在节点中的引用，驱动程序获取gpio的方法）

高通msm8909对gpio的使用@TOC

1. msm8909-pinctrl.dtsi文件中定义了诸多节点，用于设置pin组合的功能，例如：

pmx_i2c_5 {	//该名称可以随便起，无实际作用
			i2c_5_active: i2c_5_active {	//i2c_5_active是该子节点的别名，被别处引用是会用到
				mux {
					pins = "gpio19", "gpio18";
					function = "blsp_i2c5";		//定义上面两个引脚的复用功能
				};
				config {								//对pin脚的基本特性设置，如：输出电流，上拉/下拉/无上下拉
					pins = "gpio19", "gpio18";
					drive-strength = <2>; /* 2 MA */
					bias-disable; /* No PULL */
				};
			};
			i2c_5_sleep: i2c_5_sleep {
				mux {
					pins = "gpio19", "gpio18";
					function = "blsp_i2c5";
				};
				config {
					pins = "gpio19", "gpio18";
					drive-strength = <2>; /* 2 MA */
					bias-disable; /* No PULL */
				};
			};
		};

2. 假如我们要把gpio20，gpio21，gpio22作为通用gpio输出使用。
   2.1 首先，我们需要在我们的工程dtsi（msm8909-pinctrl.dtsi作为公共文件，尽量不要对其修改）中设置其复用功能，如在msm8909-mtp.dtsi中做如下定义：
   msm8909-pinctrl.dtsi的节点框架：

&soc {
	**msm_gpio**: pinctrl@1000000 {
		compatible = "qcom,msm8909-pinctrl";
		reg = <0x1000000 0x300000>;
		interrupts = <0 208 0>;
		gpio-controller;
		#gpio-cells = <2>;
		interrupt-controller;
		#interrupt-cells = <2>;
		........
		tlmm_gpio_key {
			gpio_key_active: gpio_key_active {
				mux {
					pins = "gpio90", "gpio91", "gpio92", "gpio22";
					function = "gpio";
				};

				config {
					pins = "gpio90", "gpio91", "gpio92", "gpio22";
					drive-strength = <2>;
					bias-pull-up;
				};
			};
		};
		......
	};
};

&**msm_gpio** {	//这是对msm8909-pinctrl.dtsi节点的引用
	cup_gpios {		//加入自己要用的节点
		cup_led_gpios: cup_led_gpios {	//cup_led_gpios该别名会被其他节点引用到
			mux {
				pins = "gpio20", "gpio21", "gpio22";
				function = "gpio";
			};

			config {
				pins = "gpio20", "gpio21", "gpio22";
				drive-strength = <2>;   /* 2 MA */
				bias-pull-down;	        /* PULL DOWN */
			};
		};
	};

};

2.2 对2.1中自定义节点的引用
我们还是在msm8909-mtp.dtsi中定义要和platform_driver驱动匹配的节点，如下：

	cup-leds {
		compatible = "cup-leds";
		pinctrl-names = "jeejio_cup_led_gpios";		//该名称在驱动程序中pinctrl_lookup_state函数会使用
		pinctrl-0 = <&cup_led_gpios>;						//引用2.1中定义的节点，pinctrl-0对应上面的第一个pinctrl-names,pinctrl-names可以由多个字符串组成，用逗号分割开。
		gpios = <&msm_gpio 22 0x1>,	/* R */       //定义一个gpio序列
				<&msm_gpio 21 0x1>,	/* G */
				<&msm_gpio 20 0x1>;	/* B */
	};

2.3 驱动程序中对gpio的使用

	/* Get pinctrl if target uses pinctrl */
	cup_pinctrl = devm_pinctrl_get(&pdev->dev);		//获取pinctrl句柄
	if (IS_ERR(cup_pinctrl)) {
		if (PTR_ERR(cup_pinctrl) == -EPROBE_DEFER)
			return -EPROBE_DEFER;

		pr_debug("Jeejio cup does not use pinctrl\n");
		cup_pinctrl = NULL;
	}

	set_state = pinctrl_lookup_state(cup_pinctrl, "jeejio_cup_led_gpios");	//获得cup_led_gpios
	if (IS_ERR(set_state)) {
		pr_err(	"cannot get jeejio cup pinctrl active state\n");
		return PTR_ERR(set_state);
	}

	ret = pinctrl_select_state(cup_pinctrl, set_state);	//对cup_led_gpios里的每个gpio进行设置
	if (ret) {
		pr_err(	"cannot set jeejio cup pinctrl active state\n");
		return ret;
	}

	for(i = 0; i < GPIO_NUM; i++)
	{
		cup_gpio[i] = of_get_gpio(pdev->dev.of_node, i);	//2.2中的gpio序列定义的3个gpio，其索引为：0，1，2
		ret = gpio_request(cup_gpio[i], "rgb_gpio");
		if(ret)
		{
			pr_err("request gpio err!\n");
		}
		else
		{
			pr_err("request gpio success!\n");
		}

		ret = gpio_direction_output(cup_gpio[i], 1);
		if(ret)
		{
			pr_err("set gpio direction err!\n");
		}
		else
		{
			pr_err("set gpio direction success!\n");
		}
	}

3. 另一种gpio的使用方法：

			pinctrl-names = "pmx_ts_active","pmx_ts_suspend","pmx_ts_release";
			pinctrl-0 = <&ts_int_active &ts_reset_active>;
			pinctrl-1 = <&ts_int_suspend &ts_reset_suspend>;
			pinctrl-2 = <&ts_release>;
			atmel,reset-gpio = <&msm_gpio 12 0x00>;
			atmel,irq-gpio = <&msm_gpio 13 0x00>;

上面设备树中对gpio的使用，在驱动程序中的获取方法是：

	/* reset, irq gpio info */
	pdata->gpio_reset = of_get_named_gpio_flags(np, "atmel,reset-gpio",
				0, &temp_val);
	
	pdata->gpio_irq = of_get_named_gpio_flags(np, "atmel,irq-gpio",
				0, &temp_val);