imx6ull设备树驱动--pinctl、ioctl-编程知识

imx6ull设备树驱动--pinctl、ioctl

添加pinctl节点

进入arch/arm/boot/dts目录下dts文件

在iomuxc下添加pinctl+led节点

将 GPIO1_IO03 这个 PIN 复用为 GPIO1_IO03，电气属性（配置GPIO一些列寄存器）值为 0X10B0

添加led设备节点

与上一节一样，在 / 下面添加设备节点

pinctrl-0 属性设置 LED 灯所使用的 PIN 对应的 pinctrl 节点。
led-gpio 属性指定了 LED 灯所使用的 GPIO，在这里就是 GPIO1 的 IO03，低电平
有效。

检查IO有没有被其他外设占用

一个引脚一次只能实现一个功能，否则的话驱动程序在申请 GPIO 的时候就会失败。
搜索GPIO1_IO03，发现被tsc这个外设占用了，我们没用到这个外设，直接把他注释了

除了pinctl的占用，还有设备IO的占用

除了我们使用到的，找到一个注释一个，暂时只有这两个

编译复制

设备树文件就修改好了

驱动代码

gpioled.c

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_gpio.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>#define GPIOLED_CNT      1        //device number
#define GPIOLED_NAME     "gpioled" //device name//gpioled设备结构体
struct gpioled_dev{dev_t devid;                //设备号struct cdev cdev;           //CDEVstruct class *class;        //类struct device *device;      //设备int major;                  //主设备号int minor;                  //次设备号struct device_node *nd;     //设备节点int led_gpio;   //          //led使用的GPIO编号
};struct gpioled_dev gpioled;       //设备static int led_open(struct inode *inode, struct file *filp)
{filp->private_data = &gpioled;   //设置私有数据return 0;
}static ssize_t led_read(struct file *filp, char __user *buf, size_t cnt, loff_t *offt)
{return 0;
}static ssize_t led_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt)
{int ret;unsigned char databuf[1];unsigned char ledstat;struct gpioled_dev *dev = filp->private_data;ret = copy_from_user(databuf, buf, cnt);if(ret < 0){printk("kernel copy_from_user failed: %d\n", ret);return -EFAULT;}ledstat = databuf[0];if(1 == ledstat)            //开{gpio_set_value(dev->led_gpio, 0);}else if(0 == databuf[0])    //关{gpio_set_value(dev->led_gpio, 1);}return 0;
}static int led_close(struct inode *inode, struct file *file)
{return 0;
}static struct file_operations gpioled_fops = {.owner = THIS_MODULE,.open = led_open,.read = led_read,.write = led_write,.release = led_close,
};static int __init led_init(void)
{int ret;gpioled.nd = of_find_node_by_path("/gpioled");  //通过路径查找指定节点，返回节点if(gpioled.nd == NULL){printk("find_node_by_path failed\n");return -EINVAL;}printk("gpioled node has been found\n");/* 2、 获取设备树中的 gpio 属性，得到 LED 所使用的 LED 编号 */gpioled.led_gpio = of_get_named_gpio(gpioled.nd, "led-gpio", 0);if(gpioled.led_gpio < 0) {printk("can't get led-gpio");return -EINVAL;}printk("led-gpio num = %d\r\n", gpioled.led_gpio);/* 3、设置 GPIO1_IO03 为输出，并且输出高电平，默认关闭 LED 灯 */ret = gpio_direction_output(gpioled.led_gpio, 1);if(ret < 0) {printk("can't set gpio!\r\n");}/* 注册字符设备驱动 */if(gpioled.major)                            //如果定义了设备号用它{gpioled.devid = MKDEV(gpioled.major, 0);register_chrdev_region(gpioled.devid, GPIOLED_CNT, GPIOLED_NAME);}else                                        //没定义设备号，自动创建{alloc_chrdev_region(&gpioled.devid, 0, GPIOLED_CNT, GPIOLED_NAME);gpioled.major = MAJOR(gpioled.devid);gpioled.minor = MINOR(gpioled.devid);}printk("gpioled major = %d minor = %d\n", gpioled.major, gpioled.minor);  //打印主次设备号gpioled.cdev.owner = THIS_MODULE;                //初始化cdevcdev_init(&gpioled.cdev, &gpioled_fops);cdev_add(&gpioled.cdev, gpioled.devid, GPIOLED_CNT);  //添加cdevgpioled.class = class_create(THIS_MODULE, GPIOLED_NAME);  //创建类if(IS_ERR(gpioled.class)){return PTR_ERR(gpioled.class);}gpioled.device = device_create(gpioled.class, NULL, gpioled.devid, NULL, GPIOLED_NAME);//创建设备if(IS_ERR(gpioled.device)){return PTR_ERR(gpioled.device);}return 0;
}static void __exit led_exit(void)
{cdev_del(&gpioled.cdev);unregister_chrdev_region(gpioled.devid, GPIOLED_CNT);device_destroy(gpioled.class, gpioled.devid);class_destroy(gpioled.class);
}module_init(led_init);
module_exit(led_exit);MODULE_LICENSE("GPL");

用户层代码和上一节一样

编译运行