(一)設備樹dts
紅色加粗爲修改增加部分,由於板子上只有一個LED燈,所以用蜂鳴器模擬另外一路led燈。這裏採用在根節點下創建一個leds節點下,然後在leds節點新建2路子節點 led1 和 beep 來實現。(也可以在根節點下單獨建立2個節點方式來實現)
/{
leds {
compatible = "fsl,gpio-led-test";
#address-cells = <1>;
#size-cells = <1>;
pinctrl-names = "default";
status = "okay";
led1 {
compatible = "fsl,led1-test";
pinctrl-0 = <&pinctrl_led>;
gpios-led = <&gpio1 3 GPIO_ACTIVE_LOW>;
status = "okay";
};
beep {
compatible = "fsl,beep-test";
pinctrl-0 = <&pinctrl_beep>;
gpios-beep = <&gpio5 1 GPIO_ACTIVE_LOW>;
status = "okay";
};
};
.......
}
&iomuxc {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_hog_1>;
imx6ul-evk {
pinctrl_hog_1: hoggrp-1 {
fsl,pins = <
MX6UL_PAD_UART1_RTS_B__GPIO1_IO19 0x17059 /* SD1 CD */
MX6UL_PAD_GPIO1_IO05__USDHC1_VSELECT 0x17059 /* SD1 VSELECT */
MX6UL_PAD_GPIO1_IO09__GPIO1_IO09 0x17059 /* SD1 RESET */
>;
};
pinctrl_led: ledgrp {
fsl,pins = <
MX6UL_PAD_GPIO1_IO03__GPIO1_IO03 0x10b0
>;
};
pinctrl_beep: beepgrp {
fsl,pins = <
MX6ULL_PAD_SNVS_TAMPER1__GPIO5_IO01 0x10b0
>;
};
.......
}
(二)驅動代碼:
#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 2 /* 設備號個數 */
#define GPIOLED_NAME "ledtest" /* 名字 */
#define LEDOFF 0 /* 關燈 */
#define LEDON 1 /* 開燈 */
/* gpioled 設備結構體 */
struct gpioled_dev{
dev_t devid; /* 設備號 */
struct cdev cdev; /* cdev */
struct class *class; /* 類 */
struct device *device[2]; /* 設備 */
int major; /* 主設備號 */
int minor; /* 次設備號 */
struct device_node *nd[GPIOLED_CNT]; /* 設備節點 */
int gpios[GPIOLED_CNT]; /* led 所使用的 GPIO 編號 */
};
struct gpioled_dev gpioled; /* led 設備 */
/*
* @description : 打開設備
* @param – inode : 傳遞給驅動的 inode
* @param – filp : 設備文件,file 結構體有個叫做 private_data 的成員變量
* 一般在 open 的時候將 private_data 指向設備結構體。
* @return : 0 成功;其他 失敗
*/
static int led_open(struct inode *inode, struct file *filp)
{
int minor = MINOR(inode->i_rdev);
filp->private_data = &gpioled; /* 設置私有數據 */
printk("open minor is %d\r\n",minor);
return 0;
}
/*
* @description : 從設備讀取數據
* @param – filp : 要打開的設備文件(文件描述符)
* @param - buf : 返回給用戶空間的數據緩衝區
* @param - cnt : 要讀取的數據長度
* @param – offt : 相對於文件首地址的偏移
* @return : 讀取的字節數,如果爲負值,表示讀取失敗
*/
static ssize_t led_read(struct file *filp, char __user *buf,
size_t cnt, loff_t *offt)
{
return 0;
}
/*
* @description : 向設備寫數據
* @param - filp : 設備文件,表示打開的文件描述符
* @param - buf : 要寫給設備寫入的數據
* @param - cnt : 要寫入的數據長度
* @param – offt : 相對於文件首地址的偏移
* @return : 寫入的字節數,如果爲負值,表示寫入失敗
*/
static ssize_t led_write(struct file *filp, const char __user *buf,
size_t cnt, loff_t *offt)
{
int retvalue;
unsigned char databuf[1];
unsigned char ledstat;
struct gpioled_dev *dev = filp->private_data;
int minor = MINOR(file_inode(filp)->i_rdev);/*獲取設備的子節點號,在4.x內核必須用file_inode(filp)代替filp->f_dentry->inode,不然編譯會出錯*/
printk("write inode minor is %d\r\n",minor);
retvalue = copy_from_user(databuf, buf, cnt);
if(retvalue < 0){
printk("kernel write failed!\r\n");
return -EFAULT;
}
ledstat = databuf[0]; /* 獲取狀態值 */
switch(minor){
case 0:
if(ledstat == LEDON) {
gpio_set_value(dev->gpios[0], 0); /* 打開 LED 燈 */
} else if(ledstat == LEDOFF) {
gpio_set_value(dev->gpios[0], 1); /* 關閉 LED 燈 */
}
break;
case 1:
if(ledstat == LEDON) {
gpio_set_value(dev->gpios[1], 1); /* 打開 LED 燈 */
} else if(ledstat == LEDOFF) {
gpio_set_value(dev->gpios[1], 0); /* 關閉 LED 燈 */
}
break;
default:
break;
}
return 0;
}
/*
* @description : 關閉/釋放設備
* @param – filp : 要關閉的設備文件(文件描述符)
* @return : 0 成功;其他 失敗
*/
static int led_release(struct inode *inode, struct file *filp)
{
return 0;
}
/* 設備操作函數 */
static struct file_operations gpioled_fops = {
.owner = THIS_MODULE,
.open = led_open,
.read = led_read,
.write = led_write,
.release = led_release,
};
/*
* @description : 驅動入口函數
* @param : 無
* @return : 無
*/
static int __init led_init(void)
{
int ret = 0;
struct property *proper;
/* 設置 LED 所使用的 GPIO */
/* 1、獲取設備節點:gpioled */
gpioled.nd[0] = of_find_node_by_path("/leds/led1");
if(gpioled.nd[0] == NULL) {
printk("gpioled node cant not found!\r\n");
return -EINVAL;
} else {
printk("gpioled node has been found!\r\n");
}
/* 2、 獲取設備樹中的 gpio 屬性,得到 LED 所使用的 LED 編號 */
gpioled.gpios[0] = of_get_named_gpio(gpioled.nd[0], "gpios-led", 0);
if(gpioled.gpios[0] < 0) {
printk("can't get led-gpio!\r\n");
return -EINVAL;
}
printk("led-gpio num = %d\r\n", gpioled.gpios[0]);
/* 3、設置 GPIO1_IO03 爲輸出,並且輸出高電平,默認關閉 LED 燈 */
ret = gpio_direction_output(gpioled.gpios[0], 1);
if(ret < 0) {
printk("can't set le-gpio!\r\n");
}
/*獲取字節點的compatible屬性*/
proper = of_find_property(gpioled.nd[0], "compatible", NULL);
if(proper == NULL) {
printk("compatible property find failed\r\n");
} else {
printk("led compatible = %s\r\n", (char*)proper->value);
}
/* 設置 BEEP 所使用的 GPIO */
/* 1、獲取設備節點:gpioled */
gpioled.nd[1] = of_find_node_by_path("/leds/beep");
if(gpioled.nd[1] == NULL) {
printk("gpiobeep node cant not found!\r\n");
return -EINVAL;
} else {
printk("gpiobeep node has been found!\r\n");
}
/* 2、 獲取設備樹中的 gpio 屬性,得到 LED 所使用的 LED 編號 */
gpioled.gpios[1] = of_get_named_gpio(gpioled.nd[1], "gpios-beep", 0);
if(gpioled.gpios[1] < 0) {
printk("can't get beep-gpio!\r\n");
return -EINVAL;
}
printk("beep-gpio num = %d\r\n", gpioled.gpios[1]);
/* 3、設置 GPIO1_IO03 爲輸出,並且輸出高電平,默認關閉 LED 燈 */
ret = gpio_direction_output(gpioled.gpios[1], 0);
if(ret < 0) {
printk("can't set beep-gpio!\r\n");
}
/*獲取字節點的compatible屬性*/
proper = of_find_property(gpioled.nd[0], "compatible", NULL);
if(proper == NULL) {
printk("beep compatible property find failed\r\n");
} else {
printk("beep compatible = %s\r\n", (char*)proper->value);
}
/*符設備驅動 */
/* 1、創建設備號 */
if (gpioled.major) { /* 定義了設備號 */
gpioled.devid = MKDEV(gpioled.major, 0);
register_chrdev_region(gpioled.devid, GPIOLED_CNT,
GPIOLED_NAME);
} else { /* 沒有定義設備號 */
alloc_chrdev_region(&gpioled.devid, 0, GPIOLED_CNT,
GPIOLED_NAME); /* 申請設備號 */
gpioled.major = MAJOR(gpioled.devid); /* 獲取分配號的主設備號 */
gpioled.minor = MINOR(gpioled.devid); /* 獲取分配號的次設備號 */
}
printk("gpioled major=%d,minor=%d\r\n",gpioled.major,
gpioled.minor);
/* 2、初始化 cdev */
gpioled.cdev.owner = THIS_MODULE;
cdev_init(&gpioled.cdev, &gpioled_fops);
/* 3、添加一個 cdev */
ret = cdev_add(&gpioled.cdev, gpioled.devid, GPIOLED_CNT);
if(ret)
{
printk("cdev_add erro!\r\n");
goto cdevadd_erro;
}
printk("cdev_add ok!\r\n");
/* 4、創建類 */
gpioled.class = class_create(THIS_MODULE, "my-led");
if (IS_ERR(gpioled.class)) {
printk("class_create erro!\r\n");
ret=PTR_ERR(gpioled.class);
goto class_create_erro;
}
/* 5、創建設備 */
gpioled.device[0] = device_create(gpioled.class, NULL,
MKDEV(gpioled.major,0), NULL, "led1");
if (IS_ERR(gpioled.device[0])) {
ret = PTR_ERR(gpioled.device[1]);
goto device_create1_erro;
}
/* 5、創建設備 */
gpioled.device[1] = device_create(gpioled.class, NULL,
MKDEV(gpioled.major,1), NULL, "beep");
if (IS_ERR(gpioled.device[1])) {
ret = PTR_ERR(gpioled.device[1]);
}
return 0;
device_create1_erro:
class_destroy(gpioled.class);
class_create_erro:
cdev_del(&gpioled.cdev); /* 刪除 cdev */
cdevadd_erro:
unregister_chrdev_region(gpioled.devid, GPIOLED_CNT);
return ret;
}
/*
189 * @description : 驅動出口函數
* @param : 無
* @return : 無
*/
static void __exit led_exit(void)
{
/* 註銷字符設備驅動 */
cdev_del(&gpioled.cdev); /* 刪除 cdev */
unregister_chrdev_region(gpioled.devid, GPIOLED_CNT); /* 註銷 */
device_destroy(gpioled.class, MKDEV(gpioled.major,0));
device_destroy(gpioled.class, MKDEV(gpioled.major,1));
class_destroy(gpioled.class);
}
module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("topeet");