#insmod adc.ko
#mknod /dev/beep c 253 0 //主次设备号的获取方法请见，主次设备号blog主次设备号的介绍
#chmod +x adc_test
#./adc_test //为交叉编译器编译的，上面的都应该在目标板上执行。
Makefile文件：
1.目标板的驱动makefile方法( 条件是宿主机已经装好了arm-linux-gcc)
ifneq ($(KERNELRELEASE),)
obj-m:=adc.o
else
KERNELDIR ?=/opt/FriendlyARM/linux-2.6.32.2
PWD :=$(shell pwd)
modules:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules ARCH=arm CROSS_COMPLIE=arm-none-linux-gnueabi
clean:
rm -rf *.o
.PHONY:modules clean
endif
2. x86机器上跑的makefile
obj-m :=second.o
KDIR :=/lib/modules/$(shell uname -r)/build
PWD :=$(shell pwd)
default:
$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
clean:
rm -rf *.ko
rm -rf *.mod.*
rm -rf .*.cmd
rm -rf *.o
~
adc.c源文件
1 #include <linux/errno.h>
2 #include <linux/kernel.h>
3 #include <linux/module.h>
4 #include <linux/slab.h>
5 #include <linux/input.h>
6 #include <linux/init.h>
7 #include <linux/serio.h>
8 #include <linux/delay.h>
9 #include <linux/clk.h>
10 #include <linux/wait.h>
11 #include <linux/sched.h>
12 #include <asm/io.h>
13 #include <asm/irq.h>
14 #include <asm/uaccess.h>
15 #include <mach/regs-clock.h>
16 #include <plat/regs-timer.h>
17
18 #include <plat/regs-adc.h>
19 #include <mach/regs-gpio.h>
20 #include <linux/cdev.h>
21 #include <linux/miscdevice.h>
22
23 #include "s3c24xx-adc.h"
25#undef DEBUG
27 #ifdef DEBUG
28 #define DPRINTK(x...) {printk(__FUNCTION__"(%d): ",__LINE__);printk(##x);}
29 #else
30 #define DPRINTK(x...) (void)(0)
31 #endif
32
33 #define DEVICE_NAME "adc"
34
35 static void __iomem *base_addr;
36
37 typedef struct {
38 wait_queue_head_t wait;
39 int channel;
40 int prescale;
41 }ADC_DEV;
42
43 DECLARE_MUTEX(ADC_LOCK);
//该宏声明一个信号量ADC_LOCK,并初始化它的值为0
44 static int OwnADC = 0;
45
46 static ADC_DEV adcdev;
47 static volatile int ev_adc = 0;
48 static int adc_data;
49
50 static struct clk *adc_clock;
52 #define ADCCON (*(volatile unsigned long *)(base_addr + S3C2410_ADCCO N)) //ADC control
53 #define ADCTSC (*(volatile unsigned long *)(base_addr + S3C2410_ADCTS C)) //ADC touch screen control
54 #define ADCDLY (*(volatile unsigned long *)(base_addr + S3C2410_ADCDL Y)) //ADC start or Interval Delay
55 #define ADCDAT0 (*(volatile unsigned long *)(base_addr + S3C2410_ADCDA T0)) //ADC conversion data 0
56 #define ADCDAT1 (*(volatile unsigned long *)(base_addr + S3C2410_ADCDA T1)) //ADC conversion data 1
57 #define ADCUPDN (*(volatile unsigned long *)(base_addr + 0x14)) // Stylus Up/Down interrupt status
58
59 #define PRESCALE_DIS (0 << 14)
60 #define PRESCALE_EN (1 << 14)
61 #define PRSCVL(x) ((x) << 6)
62 #define ADC_INPUT(x) ((x) << 3)
63 #define ADC_START (1 << 0)
64 #define ADC_ENDCVT (1 << 15)
65
66 #define START_ADC_AIN(ch, prescale) \
67 do{ \
68 ADCCON = PRESCALE_EN | PRSCVL(prescale) | ADC_INPUT((ch)) ; \
69 ADCCON |= ADC_START; \
70 }while(0)
71
72
73 static irqreturn_t adcdone_int_handler(int irq, void *dev_id)
74 {
75 if (OwnADC) {
76 adc_data = ADCDAT0 & 0x3ff;
77
78 ev_adc = 1;
79 wake_up_interruptible(&adcdev.wait);
80 }
81
82 return IRQ_HANDLED;
83 }
84
85 static ssize_t s3c2410_adc_read(struct file *filp, char *buffer, size_t co unt, loff_t *ppos)
86 {
87 char str[20];
88 int value;
89 size_t len;
90 if (down_trylock(&ADC_LOCK) == 0) { //该函数试着获得信号量sem，如果能够立刻获得，它就获得该信号量并返回0，否则，表示不能获得信号量sem，返回值为非0值。因此，它不会导致调用者睡眠，可以在中断上下文使用。
91 OwnADC = 1;
92 START_ADC_AIN(adcdev.channel, adcdev.prescale);
93 wait_event_interruptible(adcdev.wait, ev_adc);
94
95 ev_adc = 0;
96
97 DPRINTK("AIN[%d] = 0x%04x, %d\n", adcdev.channel, adc_data , ADCCON & 0x80 ? 1:0);
98
99 value = adc_data;
100
101 OwnADC = 0;
102 up(&ADC_LOCK); //解锁
103 } else {
104 value = -1;
105 }
106
107 len = sprintf(str, "%d\n", value);
108 if (count >= len) {
109 int r = copy_to_user(buffer, str, len);
110 return r ? r : len;
111 } else {
112 return -EINVAL;
113 }
114 }
115
116 static int s3c2410_adc_open(struct inode *inode, struct file *filp)
117 {
118 init_waitqueue_head(&(adcdev.wait));
119
120 adcdev.channel=0;
121 adcdev.prescale=0xff;
122
123 DPRINTK( "adc opened\n");
124 return 0;
125 }
126
127 static int s3c2410_adc_release(struct inode *inode, struct file *filp)
128 {
129 DPRINTK( "adc closed\n");
130 return 0;
131 }
133
134 static struct file_operations dev_fops = {
135 owner: THIS_MODULE,
136 open: s3c2410_adc_open,
137 read: s3c2410_adc_read,
138 release: s3c2410_adc_release,
139 };
140
141 static struct miscdevice misc = {
142 .minor = MISC_DYNAMIC_MINOR,
143 .name = DEVICE_NAME,
144 .fops = &dev_fops,
145 };
146
147 static int __init dev_init(void)
148 {
149 int ret;
150
151 base_addr=ioremap(S3C2410_PA_ADC,0x20); //0x20 is the size that map
152 if (base_addr == NULL) {
153 printk(KERN_ERR "Failed to remap register block\n");
return -ENOMEM;
}
一、虚拟地址的应用，就是物理地址转换为虚拟地址，ＡＤＣ驱动程序中的寄存器就是都用到了虚拟地址了。其中最主要的转换的语句是
base_addr=ioremap(S3C2410_PA_ADC,0x20);/
ioremap（）功能： 将一个IO地址空间映射到内核的虚拟地址空间上去，返回值就是虚拟地址。 物理地址和虚拟地址的转换，就是将S3C2410_PA_ADC物理地址转换为base_addr 的地址。
S3C2410_PA_ADC 为物理地址0x58000000 ，（包含了AD控制的所有寄存器）
base_addr 虚拟地址，应该是有系统分配的，调用ioremap()既能分配到。
而base_addr 的定义是 static void __iomem *base_addr;
使用完后需要 iounmap(base_addr);释放掉虚拟地址。
adc_clock = clk_get(NULL, "adc");
if (!adc_clock) {
printk(KERN_ERR "failed to get adc clock source\n");
return -ENOENT;
}
clk_enable(adc_clock);
/* normal ADC */
ADCTSC = 0;
ret = request_irq(IRQ_ADC, adcdone_int_handler, IRQF_SHARED, DEVICE_NAME, &adcdev);// shared the int
if (ret) {
iounmap(base_addr);
return ret;
}
ret = misc_register(&misc);
printk (DEVICE_NAME"\tinitialized\n");
}
static void __exit dev_exit(void)
{
free_irq(IRQ_ADC, &adcdev);
iounmap(base_addr);
if (adc_clock) {
clk_disable(adc_clock);
clk_put(adc_clock);
adc_clock = NULL;
}
misc_deregister(&misc);
}
EXPORT_SYMBOL(ADC_LOCK); // 内核符号导出使用
module_init(dev_init);
module_exit(dev_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("FriendlyARM Inc.");
测试函数adc_test.c
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <errno.h>
#include <string.h>
int main(void)
{
fprintf(stderr, "press Ctrl-C to stop\n");
int fd = open("/dev/adc", 0);
if (fd < 0) {
perror("open ADC device:");
return 1;
}
for(;;) {
char buffer[30];
int len = read(fd, buffer, sizeof buffer -1);
if (len > 0) {
buffer[len] = '\0';
int value = -1;
sscanf(buffer, "%d", &value);
printf("ADC Value: %d\n", value);
} else {
perror("read ADC device:");
return 1;
}
usleep(500* 1000); //休眠0.5秒
}
close(fd);
}