获取GPIO编号的方式
获取编号-设置为输入方式
方法：获取GPIO编号，设置该GPIO为输入模式。
建立BUTTON节点
目标设备树文件：linux-4.14.2_iTop-4412_scp/arch/arm/boot/dts/exynos4412-itop-elite.dts
首先屏蔽文件中存在”&gpx1 1”的键值对。
然后在根节点/{…}内新增如下子节点，注意status属性为”okay”
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itop_gpio_in {
compatible = "gpio_in";
status = "okay";
gpioin = <&gpx1 1 0>;
};
上面的信息指GPX1[1]初始低电平。
重新编译设备树烧录到开发板。
编写驱动文件
button_demo_drv.c
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#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("jerry");
#define DRV_NAME "gpio_in"
static int gpio_pin = 0;
static int demo_probe(struct platform_device *pdv){
struct device_node *node = pdv->dev.of_node;
int ret,value;
printk("button probe ok!\n");
gpio_pin = of_get_named_gpio(node, "gpioin", 0);
if (gpio_pin < 0)
printk("gpio_pin is not available \n");
ret = gpio_request(gpio_pin, "gpio-in");
if(ret!=0){
printk("gpio_pin request %d faigpio.", gpio_pin);
return ret;
}
printk("gpio_pin is %d\n",gpio_pin);
gpio_free(gpio_pin);
gpio_direction_input(gpio_pin);
value = gpio_get_value(gpio_pin);
printk("the value is %d\n",value);
return 0;
}
static int demo_remove(struct platform_device *pdv){
printk(KERN_EMERG "%s ok!\n",__FUNCTION__);
return 0;
}
static const struct of_device_id of_demo_dt_match[] = {
{.compatible = DRV_NAME},
{},
};
MODULE_DEVICE_TABLE(of,of_demo_dt_match);
static struct platform_driver platform_drv_demo = {
.driver = {
.name = DRV_NAME,
.owner = THIS_MODULE,
.of_match_table = of_demo_dt_match,
},
.probe = demo_probe,
.remove = demo_remove,
};
static int __init demo_init(void){
printk(KERN_EMERG "%s ok!\n",__FUNCTION__);
platform_driver_register(&platform_drv_demo);
return 0;
}
static void __exit demo_exit(void){
printk(KERN_EMERG "%s ok!\n",__FUNCTION__);
platform_driver_unregister(&platform_drv_demo);
return;
}
module_init(demo_init);
module_exit(demo_exit);
Makefile：
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#!/bin/bash
export ARCH=arm
obj-m += button_demo_drv.o
KDIR := /home/jerry/Projects/itop4412_kernel_4_14_2_bsp/linux-4.14.2_iTop-4412_scp/
PWD ?= $(shell pwd)
all:
make -C $(KDIR) M=$(PWD) modules
clean:
rm -rf *.o
交叉编译然后加载到内核后发现probe可以正常执行，打印当前按键的键值。
此外还可以用pinctrl直接设置输入模式，获取节点属性进行设置。
获取编号-设置为中断方式
方法：获取GPIO编号，转irq编号，根据irq编号申请中断。
建立BUTTON节点
目标设备树文件：linux-4.14.2_iTop-4412_scp/arch/arm/boot/dts/exynos4412-itop-elite.dts
首先屏蔽文件中存在”&gpx1 1”的键值对。
然后在根节点/{…}内新增如下子节点，注意status属性为”okay”
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itop_inter {
compatible = "itop4412,inter_pin";
status = "okay";
inter_gpio = <&gpx1 1 0>;
};
上面的信息指GPX1[1]初始低电平。
重新编译设备树烧录到开发板。
编写驱动文件
button_demo_drv.c
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#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("jerry");
#define DRV_NAME "itop4412,inter_pin"
static int inter_pin = 0;
static int irq = 0;
static irqreturn_t eint_interrupt(int irq, void *dev_id) {
printk("%s(%d)\n", __FUNCTION__, __LINE__);
printk("HOME KEY HIGH TO LOW!\n");
return IRQ_HANDLED;
}
static int demo_probe(struct platform_device *pdv){
struct device_node *node = pdv->dev.of_node;
int ret;
printk("button probe ok!\n");
inter_pin = of_get_named_gpio(node, "inter_gpio", 0);
if (inter_pin < 0)
printk("inter_pin is not available \n");
ret = gpio_request(inter_pin, "home-key-inter");
if (ret) {
printk("%s: request GPIO %d failed, ret = %d\n", DRV_NAME,inter_pin, ret);
return ret;
}
gpio_direction_input(inter_pin);
gpio_free(inter_pin);
irq = gpio_to_irq(inter_pin);
ret = request_irq(irq, eint_interrupt,IRQ_TYPE_EDGE_FALLING, "home-key-inter", pdv);
if (ret < 0) {
printk("Request IRQ %d failed, %d\n", irq,ret);
return -1;
}
return 0;
}
static int demo_remove(struct platform_device *pdv){
free_irq(irq,pdv); /*释放中断资源*/
printk(KERN_EMERG "%s ok!\n",__FUNCTION__);
return 0;
}
static const struct of_device_id of_demo_dt_match[] = {
{.compatible = DRV_NAME},
{},
};
MODULE_DEVICE_TABLE(of,of_demo_dt_match);
static struct platform_driver platform_drv_demo = {
.driver = {
.name = DRV_NAME,
.owner = THIS_MODULE,
.of_match_table = of_demo_dt_match,
},
.probe = demo_probe,
.remove = demo_remove,
};
static int __init demo_init(void){
printk(KERN_EMERG "%s ok!\n",__FUNCTION__);
platform_driver_register(&platform_drv_demo);
return 0;
}
static void __exit demo_exit(void){
printk(KERN_EMERG "%s ok!\n",__FUNCTION__);
platform_driver_unregister(&platform_drv_demo);
return;
}
module_init(demo_init);
module_exit(demo_exit);
Makefile：
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#!/bin/bash
export ARCH=arm
obj-m += button_demo_drv.o
KDIR := /home/jerry/Projects/itop4412_kernel_4_14_2_bsp/linux-4.14.2_iTop-4412_scp/
PWD ?= $(shell pwd)
all:
make -C $(KDIR) M=$(PWD) modules
clean:
rm -rf *.o
交叉编译然后加载到内核后发现probe可以正常执行，每次按下home键产生一个中断。
设备树中断属性获取中断号方式
方法：获取irq编号，根据irq编号申请中断（这里就不申请了）。
设备树文件修改
目标设备树文件：linux-4.14.2_iTop-4412_scp/arch/arm/boot/dts/exynos4412-itop-elite.dts
首先屏蔽文件中存在”&gpx1 1”、”&gpx1 2”的键值对。
然后在根节点/{…}内新增如下子节点，注意status属性为”okay”
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itop-4412-gpio-keys {
compatible = "itop-4412,gpio-keys";
status = "okay";
interrupt-parent = <&gpx1>;
interrupts = <1 0>, <2 0>;
};
上面的信息指GPX1[1]、GPX1[2]设为中断。
重新编译设备树烧录到开发板。
编写驱动文件
button_demo_drv.c
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#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_irq.h>
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("jerry");
#define DRV_NAME "itop-4412,gpio-keys"
static int demo_probe(struct platform_device *pdv){
struct device_node *node = pdv->dev.of_node;
int irq[2];
printk("button probe ok!\n");
irq[0] = irq_of_parse_and_map(node,0);
printk("irq number is %d\n",irq[0]);
irq[1] = irq_of_parse_and_map(node,1);
printk("irq number is %d\n",irq[1]);
return 0;
}
static int demo_remove(struct platform_device *pdv){
printk(KERN_EMERG "%s ok!\n",__FUNCTION__);
return 0;
}
static const struct of_device_id of_demo_dt_match[] = {
{.compatible = DRV_NAME},
{},
};
MODULE_DEVICE_TABLE(of,of_demo_dt_match);
static struct platform_driver platform_drv_demo = {
.driver = {
.name = DRV_NAME,
.owner = THIS_MODULE,
.of_match_table = of_demo_dt_match,
},
.probe = demo_probe,
.remove = demo_remove,
};
static int __init demo_init(void){
printk(KERN_EMERG "%s ok!\n",__FUNCTION__);
platform_driver_register(&platform_drv_demo);
return 0;
}
static void __exit demo_exit(void){
printk(KERN_EMERG "%s ok!\n",__FUNCTION__);
platform_driver_unregister(&platform_drv_demo);
return;
}
module_init(demo_init);
module_exit(demo_exit);
Makefile：
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#!/bin/bash
export ARCH=arm
obj-m += button_demo_drv.o
KDIR := /home/jerry/Projects/itop4412_kernel_4_14_2_bsp/linux-4.14.2_iTop-4412_scp/
PWD ?= $(shell pwd)
all:
make -C $(KDIR) M=$(PWD) modules
clean:
rm -rf *.o
交叉编译然后加载到内核后发现probe可以正常执行，打印两个中断号。
