[imx6ull]驱动常用函数
学了忘，忘了学
2021/12/4
映射物理内存
1#define ioremap(cookie,size)
2void iounmap (volatile void __iomem *addr)
I/O 内存访问函数
读
1u8 readb(const volatile void __iomem *addr)
2u16 readw(const volatile void __iomem *addr)
3u32 readl(const volatile void __iomem *addr)
写
1void writeb(u8 value, volatile void __iomem *addr)
2void writew(u16 value, volatile void __iomem *addr)
3void writel(u32 value, volatile void __iomem *addr)
老注册函数register_chrdev unregister_chrdev
新注册
新分配和释放设备号
1int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, const char *name)
2int register_chrdev_region(dev_t from, unsigned count, const char *name)
3void unregister_chrdev_region(dev_t from, unsigned count)
新字符设备注册方法
1void cdev_init(struct cdev *cdev, const struct file_operations *fops)
2int cdev_add(struct cdev *p, dev_t dev, unsigned count)
3void cdev_del(struct cdev *p)
自动创建设备节点
1struct class *class_create (struct module *owner, const char *name)
2void class_destroy(struct class *cls);
3
4struct device *device_create(struct class *class,
5 struct device *parent,
6 dev_t devt,
7 void *drvdata,
8 const char *fmt, ...)
9void device_destroy(struct class *class, dev_t devt)
文件私有数据
struct file *filp 这个参数设置
例程
1#include <linux/types.h>
2#include <linux/kernel.h>
3#include <linux/delay.h>
4#include <linux/ide.h>
5#include <linux/init.h>
6#include <linux/module.h>
7#include <linux/errno.h>
8#include <linux/gpio.h>
9#include <linux/cdev.h>
10#include <linux/device.h>
11#include <asm/mach/map.h>
12#include <asm/uaccess.h>
13#include <asm/io.h>
14
15#define NEWCHRLED_CNT 1 /* 设备号个数 */
16#define NEWCHRLED_NAME "newchrled" /* 名字 */
17#define LEDOFF 0 /* 关灯 */
18#define LEDON 1 /* 开灯 */
19
20/* 寄存器物理地址 */
21#define CCM_CCGR1_BASE (0X020C406C)
22#define SW_MUX_GPIO1_IO03_BASE (0X020E0068)
23#define SW_PAD_GPIO1_IO03_BASE (0X020E02F4)
24#define GPIO1_DR_BASE (0X0209C000)
25#define GPIO1_GDIR_BASE (0X0209C004)
26
27/* 映射后的寄存器虚拟地址指针 */
28static void __iomem *IMX6U_CCM_CCGR1;
29static void __iomem *SW_MUX_GPIO1_IO03;
30static void __iomem *SW_PAD_GPIO1_IO03;
31static void __iomem *GPIO1_DR;
32static void __iomem *GPIO1_GDIR;
33
34/* newchrled设备结构体 */
35struct newchrled_dev{
36 dev_t devid; /* 设备号 */
37 struct cdev cdev; /* cdev */
38 struct class *class; /* 类 */
39 struct device *device; /* 设备 */
40 int major; /* 主设备号 */
41 int minor; /* 次设备号 */
42};
43
44struct newchrled_dev newchrled; /* led设备 */
45
46
47void led_switch(u8 sta)
48{
49 u32 val = 0;
50 if(sta == LEDON) {
51 val = readl(GPIO1_DR);
52 val &= ~(1 << 3);
53 writel(val, GPIO1_DR);
54 }else if(sta == LEDOFF) {
55 val = readl(GPIO1_DR);
56 val|= (1 << 3);
57 writel(val, GPIO1_DR);
58 }
59}
60
61
62static int led_open(struct inode *inode, struct file *filp)
63{
64 filp->private_data = &newchrled; /* 设置私有数据 */
65 return 0;
66}
67
68
69static ssize_t led_read(struct file *filp, char __user *buf, size_t cnt, loff_t *offt)
70{
71 return 0;
72}
73
74
75static ssize_t led_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt)
76{
77 int retvalue;
78 unsigned char databuf[1];
79 unsigned char ledstat;
80
81 retvalue = copy_from_user(databuf, buf, cnt);
82 if(retvalue < 0) {
83 printk("kernel write failed!\r\n");
84 return -EFAULT;
85 }
86
87 ledstat = databuf[0]; /* 获取状态值 */
88
89 if(ledstat == LEDON) {
90 led_switch(LEDON); /* 打开LED灯 */
91 } else if(ledstat == LEDOFF) {
92 led_switch(LEDOFF); /* 关闭LED灯 */
93 }
94 return 0;
95}
96
97
98static int led_release(struct inode *inode, struct file *filp)
99{
100 return 0;
101}
102
103static struct file_operations newchrled_fops = {
104 .owner = THIS_MODULE,
105 .open = led_open,
106 .read = led_read,
107 .write = led_write,
108 .release = led_release,
109};
110
111
112static int __init led_init(void)
113{
114 u32 val = 0;
115
116 IMX6U_CCM_CCGR1 = ioremap(CCM_CCGR1_BASE, 4);
117 SW_MUX_GPIO1_IO03 = ioremap(SW_MUX_GPIO1_IO03_BASE, 4);
118 SW_PAD_GPIO1_IO03 = ioremap(SW_PAD_GPIO1_IO03_BASE, 4);
119 GPIO1_DR = ioremap(GPIO1_DR_BASE, 4);
120 GPIO1_GDIR = ioremap(GPIO1_GDIR_BASE, 4);
121
122
123 val = readl(IMX6U_CCM_CCGR1);
124 val &= ~(3 << 26); /* 清楚以前的设置 */
125 val |= (3 << 26); /* 设置新值 */
126 writel(val, IMX6U_CCM_CCGR1);
127
128 writel(5, SW_MUX_GPIO1_IO03);
129
130 writel(0x10B0, SW_PAD_GPIO1_IO03);
131
132 /* 4、设置GPIO1_IO03为输出功能 */
133 val = readl(GPIO1_GDIR);
134 val &= ~(1 << 3); /* 清除以前的设置 */
135 val |= (1 << 3); /* 设置为输出 */
136 writel(val, GPIO1_GDIR);
137
138 /* 5、默认关闭LED */
139 val = readl(GPIO1_DR);
140 val |= (1 << 3);
141 writel(val, GPIO1_DR);
142
143 /* 注册字符设备驱动 */
144 /* 1、创建设备号 */
145 if (newchrled.major) { /* 定义了设备号 */
146 newchrled.devid = MKDEV(newchrled.major, 0);
147 register_chrdev_region(newchrled.devid, NEWCHRLED_CNT, NEWCHRLED_NAME);
148 } else { /* 没有定义设备号 */
149 alloc_chrdev_region(&newchrled.devid, 0, NEWCHRLED_CNT, NEWCHRLED_NAME); /* 申请设备号 */
150 newchrled.major = MAJOR(newchrled.devid); /* 获取分配号的主设备号 */
151 newchrled.minor = MINOR(newchrled.devid); /* 获取分配号的次设备号 */
152 }
153 printk("newcheled major=%d,minor=%d\r\n",newchrled.major, newchrled.minor);
154
155 /* 2、初始化cdev */
156 newchrled.cdev.owner = THIS_MODULE;
157 cdev_init(&newchrled.cdev, &newchrled_fops);
158
159 /* 3、添加一个cdev */
160 cdev_add(&newchrled.cdev, newchrled.devid, NEWCHRLED_CNT);
161
162 /* 4、创建类 */
163 newchrled.class = class_create(THIS_MODULE, NEWCHRLED_NAME);
164 if (IS_ERR(newchrled.class)) {
165 return PTR_ERR(newchrled.class);
166 }
167
168 /* 5、创建设备 */
169 newchrled.device = device_create(newchrled.class, NULL, newchrled.devid, NULL, NEWCHRLED_NAME);
170 if (IS_ERR(newchrled.device)) {
171 return PTR_ERR(newchrled.device);
172 }
173
174 return 0;
175}
176
177
178static void __exit led_exit(void)
179{
180 /* 取消映射 */
181 iounmap(IMX6U_CCM_CCGR1);
182 iounmap(SW_MUX_GPIO1_IO03);
183 iounmap(SW_PAD_GPIO1_IO03);
184 iounmap(GPIO1_DR);
185 iounmap(GPIO1_GDIR);
186
187 /* 注销字符设备驱动 */
188 cdev_del(&newchrled.cdev);/* 删除cdev */
189 unregister_chrdev_region(newchrled.devid, NEWCHRLED_CNT); /* 注销设备号 */
190
191 device_destroy(newchrled.class, newchrled.devid);
192 class_destroy(newchrled.class);
193}
194
195module_init(led_init);
196module_exit(led_exit);
197MODULE_LICENSE("GPL");
198MODULE_AUTHOR("aeneag");
重新回忆一下驱动的常用函数
吾心信其可行，
则移山填海之难，
终有成功之日！
——孙文
则移山填海之难，
终有成功之日！
——孙文
评论
0 评论
