------------------------------------------------------------------------------------------------------------------------------
交叉编译器：arm-linux-gcc-4.5.4
Linux内核版本：Linux-3.0
主机操作系统：Centos 6.5
开发板：FL2440
温度传感器:ds18b20
------------------------------------------------------------------------------------------------------------------------------
之前看过led的，platform_led的，platform_button的。当时以为看懂了，可是真的拿到一个模块要去写他的驱动的时候发现有些无从下手。于是借鉴了朋友的一篇混杂设备驱动，半抄半写的写出来了一个miscdevice类型的驱动。之后又在miscdevice与led的基础上写出来了cdev类型的驱动。并附上一个小小的测试程序。
一、miscdevice驱动
1 #include <linux/interrupt.h>
2 #include <linux/poll.h>
3 #include <linux/configfs.h>
4 #include <linux/module.h>
5 #include <linux/kernel.h>
6 #include <linux/fs.h>
7 #include <linux/clk.h>
8 #include <linux/init.h>
9 #include <linux/device.h>
10 #include <linux/miscdevice.h>
11 #include <linux/delay.h>
12 #include <linux/mm.h>
13 #include <plat/regs-timer.h>
14 #include <mach/regs-gpio.h>
15 #include <mach/map.h>
16 #include <mach/gpio-nrs.h>
17 #include <mach/regs-irq.h>
18 #include <asm/io.h>
19 #include <mach/hardware.h>
20 #include <asm/uaccess.h>
21 #include <asm/system.h>
22 #include <mach/regs-clock.h>
23 #include <asm/irq.h>
24 #include <linux/types.h>
25 #include <linux/moduleparam.h>
26 #include <linux/slab.h>
27 #include <linux/errno.h>
28 #include <linux/ioctl.h>
29 #include <linux/cdev.h>
30 #include <linux/string.h>
31 #include <linux/list.h>
32 #include <linux/pci.h>
33 #include <asm/atomic.h>
34 #include <asm/unistd.h>
35 #include <linux/miscdevice.h>
36 #include <linux/gpio.h>
37
38 /*********************************************************************************
39 * Copyright: (C) 2016 2013dianxin_3
40 * All rights reserved.
41 *
42 * Filename: ds18b20.c
43 * Description: This file
44 *
45 * Version: 1.0.0(08/07/2016)
46 * Author: xiaohexiansheng <[email protected]>
47 * ChangeLog: 1, Release initial version on "08/07/2016 02:21:17 PM"
48 *
49 ********************************************************************************/
50 #define DRV_AUTHOR "xiaohexiansheng <[email protected]>"
51 #define DRV_DESC "s3c2440 ds18b20 driver"
52 #define DEVICE_NAME "ds18b20"
53
54 #define LOW 0
55 #define HIGH 1
56 typedef unsigned char BYTE;
57
58 static BYTE data[2];
59
60 BYTE ds18b20_reset(void)
61 {
62 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT); //配置GP0输出模式
63 s3c2410_gpio_setpin(S3C2410_GPG(0), LOW); //向ds18b20发送一个下降沿，并保持480us
64 udelay(480);
65 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH); //向ds18b20发送一个上升沿，此时可释放ds18b20总线
66 udelay(60);
67
68 //以上动作是给ds18b20一个复位脉冲，通过配置GPIO引脚为输入模式可检测ds18b20是否复位成功
69 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_INPUT);
70 //若总线在释放后为高电平，则复位失败
71 if(s3c2410_gpio_getpin(S3C2410_GPG(0)))
72 {
73 printk("ds18b20 reset failed.\r\n");
74 return 1;
75 }
76 udelay(240);
77 return 0;
78 }
79
80 BYTE ds18b20_read_byte(void)
81 {
82 BYTE i = 0;
83 BYTE byte = 0;
84 // 读“1”时隙：
85 // 若总线状态保持在低电平状态1微秒到15微秒之间
86 // 然后跳变到高电平状态且保持在15微秒到60微秒之间
87 // 就认为从DS18B20读到一个“1”信号
88 // 理想情况: 1微秒的低电平然后跳变再保持60微秒的高电平
89 // 读“0”时隙：
90 // 若总线状态保持在低电平状态15微秒到30微秒之间
91 // 然后跳变到高电平状态且保持在15微秒到60微秒之间
92 // 就认为从DS18B20读到一个“0”信号
93 // 理想情况: 15微秒的低电平然后跳变再保持46微秒的高电平
94 for(i = 0; i < 8; i++)
95 {
96 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);
97
98 s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
99 udelay(1);
100 byte >>= 1;
101 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
102 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_INPUT);
103 // 若总线在我们设它为低电平之后若1微秒之内变为高
104 // 则认为从DS18B20处收到一个“1”信号
105 // 因此把byte的D7为置“1”
106 if(s3c2410_gpio_getpin(S3C2410_GPG(0)))
107 byte |= 0x80;
108 udelay(50);
109 }
110 return byte;
111 }
112
113 BYTE ds18b20_write_byte(BYTE byte)
114 {
115 BYTE i;
116 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT); // 配置GPG0为输出模式
117 // 写“1”时隙：
118 // 保持总线在低电平1微秒到15微秒之间
119 // 然后再保持总线在高电平15微秒到60微秒之间
120 // 理想状态: 1微秒的低电平然后跳变再保持60微秒的高电平
121 // 写“0”时隙：
122 // 保持总线在低电平15微秒到60微秒之间
123 // 然后再保持总线在高电平1微秒到15微秒之间
124 // 理想状态: 60微秒的低电平然后跳变再保持1微秒的高电平
125 for(i = 0; i < 8; i++)
126 {
127 s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
128 udelay(15);
129 if(byte & HIGH)
130 {
131 // 若byte变量的D0位是1，则需向总线上写“1”
132 // 根据写“1”时隙规则，电平在此处翻转为高
133 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
134 }
135 else
136 {
137 // 若byte变量的D0位是0，则需向总线上写“0”
138 // 根据写“0”时隙规则，电平在保持为低
139 s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
140 }
141 // 电平状态保持60微秒
142 udelay(45);
143
144 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH); //释放总线
145 udelay(1);
146 byte >>= 1;
147 }
148 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH); //释放总线
149 }
150
151 void ds18b20_proc(void) //读取温度
152 {
153 while(ds18b20_reset()); //循环判断DS18B20直到复位，延时120ms;
154 udelay(120);
155 ds18b20_write_byte(0xcc); //写入CCH命令，跳过读序列号过程;
156 ds18b20_write_byte(0x44); //写入44H命令，开始温度转换，延时5 ms;
157 udelay(5);
158
159 while(ds18b20_reset()); //循环判断DS18B20直到复位，延时200 ms;
160 udelay(200);
161 ds18b20_write_byte(0xcc); //写入CCH命令，跳过读序列号过程;
162 ds18b20_write_byte(0xbe); //写入BEH命令，读取寄存器;
163
164 data[0] = ds18b20_read_byte(); //读温度整数部分;
165 data[1] = ds18b20_read_byte(); //读温度小数部分
166 }
167
168 static ssize_t s3c2440_ds18b20_read(struct file *filp, char *buff, size_t len, loff_t *off)
169 {
170 ds18b20_proc();
171
172 buff[0] = data[0];
173 buff[1] = data[1];
174
175 return 1;
176 }
177
178 static struct file_operations s3c2440_ds18b20_fops =
179 {
180 .owner = THIS_MODULE,
181 .read = s3c2440_ds18b20_read,
182 };
183
184 static struct miscdevice misc =
185 {
186 .minor = MISC_DYNAMIC_MINOR,
187 .name = DEVICE_NAME,
188 .fops = &s3c2440_ds18b20_fops,
189 };
190
191 static int __init s3c2440_ds18b20_init(void)
192 {
193 int result;
194 result = misc_register(&misc);
195 printk(DEVICE_NAME "initialized.\n");
196
197 while(ds18b20_reset());
198 return result;
199 }
200
201 static void __exit s3c2440_ds18b20_exit(void)
202 {
203 misc_deregister(&misc);
204 }
205
206 module_init(s3c2440_ds18b20_init);
207 module_exit(s3c2440_ds18b20_exit);
208 MODULE_AUTHOR(DRV_AUTHOR);
209 MODULE_DESCRIPTION(DRV_DESC);
210 MODULE_LICENSE("GPL");
二、cdevdevice驱动
1 #include <linux/module.h>
2 #include <linux/init.h>
3 #include <linux/kernel.h>
4 #include <linux/fs.h>
5 #include <linux/delay.h>
6 #include <asm/irq.h>
7 #include <mach/regs-gpio.h>
8 #include <mach/hardware.h>
9 #include <linux/cdev.h>
10 #include <linux/device.h>
11 #include <linux/kdev_t.h>
12 #include <asm/uaccess.h>
13 #include <linux/platform_device.h>
14 #include <linux/gpio.h>
15
16 /*********************************************************************************
17 * Copyright: (C) 2016 2013dianxin_3
18 * All rights reserved.
19 *
20 * Filename: ds18b20.c
21 * Description: This file
22 *
23 * Version: 1.0.0(08/08/2016)
24 * Author: xiaohexiansheng <[email protected]>
25 * ChangeLog: 1, Release initial version on "08/08/2016 03:44:48 PM"
26 *
27 ********************************************************************************/
28 #define DRV_AUTHOR "xiaohexiansheng <[email protected]>"
29 #define DRV_DESC "S3C2440 ds18b20 driver"
30
31 #define DEV_NAME "ds18b20"
32 #define DISABLE 0
33 #define DRV_MAJOR_VER 1
34 #define DRV_MINOR_VER 0
35 #define DRV_REVER_VER 0
36
37 #define LOW 0
38 #define HIGH 1
39
40 #ifndef DEV_MAJOR
41 #define DEV_MAJOR 0
42 #endif
43
44 int dev_major = DEV_MAJOR;
45 int dev_minor = 0;
46 int debug = DISABLE;
47
48 static struct cdev *ds18b20_cdev;
49
50 typedef unsigned char BYTE;
51 static BYTE data[2];
52
53 BYTE ds18b20_reset(void)
54 {
55 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);
56 s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
57 udelay(480);
58 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
59 udelay(60);
60
61 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_INPUT);
62 if(s3c2410_gpio_getpin(S3C2410_GPG(0)))
63 {
64 printk("ds18b20 reset failed.\r\n");
65 return 1;
66 }
67 udelay(240);
68 return 0;
69 }
70
71 BYTE ds18b20_read_byte(void)
72 {
73 BYTE i = 0;
74 BYTE byte = 0;
75
76 for(i = 0; i < 8; i++)
77 {
78 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);
79 s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
80 udelay(1);
81 byte >>= 1;
82 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
83 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_INPUT);
84 if(s3c2410_gpio_getpin(S3C2410_GPG(0)))
85 byte |= 0x80;
86 udelay(50);
87 }
88 return byte;
89 }
90
91 BYTE ds18b20_write_byte(BYTE byte)
92 {
93 BYTE i;
94 s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);
95 for(i = 0; i < 8; i++)
96 {
97 s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
98 udelay(15);
99 if(byte & HIGH)
100 {
101 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
102 }
103 else
104 {
105 s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
106 }
107 udelay(45);
108
109 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
110 udelay(1);
111 byte >>= 1;
112 }
113 s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
114 return 0;
115 }
116
117 void ds18b20_proc(void)
118 {
119 while(ds18b20_reset());
120 udelay(120);
121 ds18b20_write_byte(0xcc);
122 ds18b20_write_byte(0x44);
123 udelay(5);
124
125 while(ds18b20_reset());
126 udelay(200);
127 ds18b20_write_byte(0xcc);
128 ds18b20_write_byte(0xbe);
129
130 data[0] = ds18b20_read_byte();
131 data[1] = ds18b20_read_byte();
132 }
133
134 static ssize_t s3c2440_ds18b20_read(struct file *filp, char *buff, size_t len, loff_t *off)
135 {
136 ds18b20_proc();
137
138 buff[0] = data[0];
139 buff[1] = data[1];
140
141 return 1;
142 }
143
144 static struct file_operations ds18b20_fops =
145 {
146
147 .owner = THIS_MODULE,
148 .read = s3c2440_ds18b20_read,
149 };
150
151 static int __init s3c_ds18b20_init(void)
152 {
153 int result;
154 dev_t devno;
155
156 if(0 != ds18b20_reset())
157 {
158 printk(KERN_ERR "s3c2440 ds18b20 hardware initialize failure.\n");
159 return -ENODEV;
160 }
161
162 if(0 != dev_major)
163 {
164 devno = MKDEV(dev_major, 0);
165 result = register_chrdev_region(devno, 1, DEV_NAME);
166 }
167 else
168 {
169 result = alloc_chrdev_region(&devno, dev_minor, 1, DEV_NAME);
170 dev_major = MAJOR(devno);
171 }
172
173 if(result < 0)
174 {
175 printk(KERN_ERR "s3c %s driver cannot use major %d.\n", DEV_NAME, dev_major);
176 return -ENODEV;
177 }
178 printk(KERN_DEBUG "s3c %s driver use major %d.\n", DEV_NAME, dev_major);
179
180 if(NULL == (ds18b20_cdev = cdev_alloc()))
181 {
182 printk(KERN_ERR "s3c %s driver cannot register cdev: result = %d.\n", DEV_NAME, result);
183 unregister_chrdev_region(devno, 1);
184 return -ENOMEM;
185 }
186
187 ds18b20_cdev -> owner = THIS_MODULE;
188 cdev_init(ds18b20_cdev, &ds18b20_fops);
189
190 result = cdev_add(ds18b20_cdev, devno, 1);
191 if(0 != result)
192 {
193 printk(KERN_ERR "s3c %s driver cannot register cdev: result = %d.\n", DEV_NAME, result);
194 goto ERROR;
195 }
196
197 printk(KERN_ERR "s3c %s driver[major=%d] Version %d.%d.%d installed successfully.\n",DEV_NAME, dev_major, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
198 return 0;
199
200 ERROR:
201 printk(KERN_ERR "s3c %s driver installed failure./", DEV_NAME);
202 cdev_del(ds18b20_cdev);
203 unregister_chrdev_region(devno, 1);
204 return result;
205 }
206
207 static void __exit s3c_ds18b20_exit(void)
208 {
209 dev_t devno = MKDEV(dev_major, dev_minor);
210
211 cdev_del(ds18b20_cdev);
212 unregister_chrdev_region(devno, 1);
213
214 printk(KERN_ERR "s3c %s driver version %d.%d.%d removed!\n", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
215 return;
216 }
217
218 module_init(s3c_ds18b20_init);
219 module_exit(s3c_ds18b20_exit);
220
221 module_param(debug, int, S_IRUGO);
222 module_param(dev_major, int ,S_IRUGO);
223
224 MODULE_AUTHOR(DRV_AUTHOR);
225 MODULE_DESCRIPTION(DRV_DESC);
226 MODULE_LICENSE("GPL");
注：cdev的驱动需要手动创建设备节点，而misc不需要
三、测试程序
1 /*********************************************************************************
2 * Copyright: (C) 2016 2013dianxin_3
3 * All rights reserved.
4 *
5 * Filename: dsapp.c
6 * Description: This file
7 *
8 * Version: 1.0.0(08/08/2016)
9 * Author: xiaohexiansheng <[email protected]>
10 * ChangeLog: 1, Release initial version on "08/08/2016 10:19:25 AM"
11 *
12 ********************************************************************************/
13 #include <stdio.h>
14 #include <sys/types.h>
15 #include <sys/ioctl.h>
16 #include <stdlib.h>
17 #include <termios.h>
18 #include <sys/stat.h>
19 #include <fcntl.h>
20 #include <sys/time.h>
21
22 /********************************************************************************
23 * Description:
24 * Input Args:
25 * Output Args:
26 * Return Value:
27 ********************************************************************************/
28 int main (int argc, char **argv)
29 {
30 int fd;
31 double result = 0;
32 unsigned char buff[2];
33 unsigned short temp = 0;
34 int flag = 0;
35
36 if ((fd=open("/dev/ds18b20",O_RDWR | O_NDELAY | O_NOCTTY)) < 0)
37 {
38 perror("open device ds18b20 failed.\r\n");
39 exit(1);
40 }
41 while(1)
42 {
43 printf("open device ds18b20 success.\r\n");
44 read(fd, buff, sizeof(buff));
45 temp=((unsigned short)buff[1])<<8;
46 temp|=(unsigned short)buff[0];
47 result=0.0625*((double)temp);
48 printf("temperature is %4f \r\n", result);
49 sleep(2);
50 }
51 close(fd);
52
53 return 0;
54 } /* ----- End of main() ----- */
时间： 2024-10-24 15:25:03