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2019-03-14
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摘要：本文主要向大家介绍了C/C++知识点之字符驱动，通过具体的内容向大家展示，希望对大家学习C/C++知识点有所帮助。
本文主要向大家介绍了C/C++知识点之字符驱动，通过具体的内容向大家展示，希望对大家学习C/C++知识点有所帮助。
//#include <linux/config.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/kernel.h> /* printk() */
#include <linux/slab.h> /* kmalloc() */
#include <linux/fs.h> /* everything... */
#include <linux/errno.h> /* error codes */
#include <linux/types.h> /* size_t */
#include <linux/mm.h>
#include <linux/kdev_t.h>
#include <asm/page.h>
#include <linux/cdev.h>
#include <linux/device.h>
//主设备号
static int simple_major = 0;
//从设置号
static int minor=0;
module_param(simple_major, int, 0);
MODULE_AUTHOR("Jonathan Corbet");
MODULE_LICENSE("Dual BSD/GPL");
int simple_open (struct inode *inode, struct file *filp)
{
return 0;
}
static int simple_release(struct inode *inode, struct file *filp)
{
return 0;
}
void simple_vma_open(struct vm_area_struct *vma)
{
printk(KERN_NOTICE "Simple VMA open, virt %lx, phys %lx\n",
vma->vm_start, vma->vm_pgoff << PAGE_SHIFT);
}
void simple_vma_close(struct vm_area_struct *vma)
{
printk(KERN_NOTICE "Simple VMA close.\n");
}
static struct vm_operations_struct simple_remap_vm_ops = {
.open = simple_vma_open,
.close = simple_vma_close,
};
static int simple_remap_mmap(struct file *filp, struct vm_area_struct *vma)
{
if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start,
vma->vm_page_prot))
return -EAGAIN;
vma->vm_ops = &simple_remap_vm_ops;
simple_vma_open(vma);
return 0;
}
struct page *simple_vma_nopage(struct vm_area_struct *vma,
unsigned long address, int *type)
{
struct page *pageptr;
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
unsigned long physaddr = address - vma->vm_start + offset;
unsigned long pageframe = physaddr >> PAGE_SHIFT;
// Eventually remove these printks
printk (KERN_NOTICE "---- Nopage, off %lx phys %lx\n", offset, physaddr);
printk (KERN_NOTICE "VA is %p\n", __va (physaddr));
printk (KERN_NOTICE "Page at %p\n", virt_to_page (__va (physaddr)));
if (!pfn_valid(pageframe))
//return NOPAGE_SIGBUS;
return NULL;
pageptr = pfn_to_page(pageframe);
printk (KERN_NOTICE "page->index = %ld mapping %p\n", pageptr->index, pageptr->mapping);
printk (KERN_NOTICE "Page frame %ld\n", pageframe);
get_page(pageptr);
if (type)
*type = VM_FAULT_MINOR;
return pageptr;
}
static struct vm_operations_struct simple_nopage_vm_ops = {
.open = simple_vma_open,
.close = simple_vma_close,
//.nopage = simple_vma_nopage,
};
static int simple_nopage_mmap(struct file *filp, struct vm_area_struct *vma)
{
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
if (offset >= __pa(high_memory) || (filp->f_flags & O_SYNC))
vma->vm_flags |= VM_IO;
// vma->vm_flags |= VM_RESERVED;
vma->vm_flags |=(VM_DONTEXPAND | VM_DONTDUMP);
vma->vm_ops = &simple_nopage_vm_ops;
simple_vma_open(vma);
return 0;
}
/*
* Set up the cdev structure for a device.
*/
//https://www.cnblogs.com/chen-farsight/p/6181341.html
//struct file_operations {
// struct module *owner;//拥有该结构的模块的指针，一般为THIS_MODULES
// loff_t (*llseek) (struct file *, loff_t, int);//用来修改文件当前的读写位置
// ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);//从设备中同步读取数据
// ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);//向设备发送数据
// ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);//初始化一个异步的读取操作
// ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);//初始化一个异步的写入操作
// int (*readdir) (struct file *, void *, filldir_t);//仅用于读取目录，对于设备文件，该字段为NULL
// unsigned int (*poll) (struct file *, struct poll_table_struct *); //轮询函数，判断目前是否可以进行非阻塞的读写或写入
// int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long); //执行设备I/O控制命令
// long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); //不使用BLK文件系统，将使用此种函数指针代替ioctl
// long (*compat_ioctl) (struct file *, unsigned int, unsigned long); //在64位系统上，32位的ioctl调用将使用此函数指针代替
// int (*mmap) (struct file *, struct vm_area_struct *); //用于请求将设备内存映射到进程地址空间
// int (*open) (struct inode *, struct file *); //打开
// int (*flush) (struct file *, fl_owner_t id);
// int (*release) (struct inode *, struct file *); //关闭
// int (*fsync) (struct file *, struct dentry *, int datasync); //刷新待处理的数据
// int (*aio_fsync) (struct kiocb *, int datasync); //异步刷新待处理的数据
// int (*fasync) (int, struct file *, int); //通知设备FASYNC标志发生变化
// int (*lock) (struct file *, int, struct file_lock *);
// ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
// unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
// int (*check_flags)(int);
// int (*flock) (struct file *, int, struct file_lock *);
// ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
// ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
// int (*setlease)(struct file *, long, struct file_lock **);
//};
static void simple_setup_cdev(struct cdev *dev, int minor,
struct file_operations *fops)
{
int err, devno = MKDEV(simple_major, minor);
//字符设备注册
cdev_init(dev, fops);
//当前模块挺有这个设备
dev->owner = THIS_MODULE;
dev->ops = fops;
//添加
err = cdev_add (dev, devno, 1);
if (err)
printk (KERN_NOTICE "Error %d adding simple%d", err, minor);
}
//初始化
static struct file_operations simple_remap_ops = {
.owner = THIS_MODULE,
.open = simple_open,
.release = simple_release,
.mmap = simple_remap_mmap,
};
//初始化
static struct file_operations simple_nopage_ops = {
.owner = THIS_MODULE,
.open = simple_open,
.release = simple_release,
.mmap = simple_nopage_mmap,
};
#define MAX_SIMPLE_DEV 2
#if 0
static struct file_operations *simple_fops[MAX_SIMPLE_DEV] = {
&simple_remap_ops,
&simple_nopage_ops,
};
#endif
//俩个简单的字符设备
static struct cdev SimpleDevs[MAX_SIMPLE_DEV];
static int simple_init(void)
{
int result;
//MKDEV是将主设备号和次设备号转换成dev_t类型
dev_t dev = MKDEV(simple_major, minor);
//找出设备号
if (simple_major)
//进行字符设备设备节点的分配
result = register_chrdev_region(dev, 2, "simple");
else {
//动态申请
result = alloc_chrdev_region(&dev, 0, 2, "simple");
simple_major = MAJOR(dev);
}
if (result < 0) {
printk(KERN_WARNING "simple: unable to get major %d\n", simple_major);
return result;
}
if (simple_major == 0)
simple_major = result;
printk(KERN_WARNING "haha!!!!\n");
//设置俩个字符设备
simple_setup_cdev(SimpleDevs, 0, &simple_remap_ops);
simple_setup_cdev(SimpleDevs + 1, 1, &simple_nopage_ops);
return 0;
}
static void simple_cleanup(void)
{
cdev_del(SimpleDevs);
cdev_del(SimpleDevs + 1);
unregister_chrdev_region(MKDEV(simple_major, 0), 2);
}
module_init(simple_init);
module_exit(simple_cleanup);
obj-m := hello.o
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
all:
$(MAKE) -C $(KERNELDIR) M=$(PWD)
clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions
root@ubuntu:~/Desktop# make
make -C /lib/modules/4.2.0-27-generic/build M=/root/Desktop
make[1]: Entering directory `/usr/src/linux-headers-4.2.0-27-generic'
LD /root/Desktop/built-in.o
CC [M] /root/Desktop/hello.o
Building modules, stage 2.
MODPOST 1 modules
CC /root/Desktop/hello.mod.o
LD [M] /root/Desktop/hello.ko
make[1]: Leaving directory `/usr/src/linux-headers-4.2.0-27-generic'
root@ubuntu:~/Desktop# insmod ./hello.ko
insmod: ERROR: could not insert module ./hello.ko: File exists
root@ubuntu:~/Desktop# lsmod
Module Size Used by
hello 16384 0
coretemp 16384 0
crct10dif_pclmul 16384 0
crc32_pclmul 16384 0
aesni_intel 167936 0
snd_ens1371 28672 0
snd_ac97_codec 131072 1 snd_ens1371
aes_x86_64 20480 1 aesni_intel
gameport 16384 1 snd_ens1371
ac97_bus 16384 1 snd_ac97_codec
vmw_balloon 16384 0
lrw 16384 1 aesni_intel
gf128mul 16384 1 lrw
glue_helper 16384 1 aesni_intel
ablk_helper 16384 1 aesni_intel
snd_pcm 102400 2 snd_ac97_codec,snd_ens1371
cryptd 20480 2 aesni_intel,ablk_helper
snd_seq_midi 16384 0
snd_seq_midi_event 16384 1 snd_seq_midi
input_leds 16384 0
joydev 20480 0
serio_raw 16384 0
snd_rawmidi 32768 2 snd_ens1371,snd_seq_midi
snd_seq 69632 2 snd_seq_midi_event,snd_seq_midi
vmwgfx 172032 3
snd_seq_device 16384 3 snd_seq,snd_rawmidi,snd_seq_midi
ttm 94208 1 vmwgfx
snd_timer 32768 2 snd_pcm,snd_seq
btusb 45056 0
drm_kms_helper 126976 1 vmwgfx
snd 81920 7 snd_ac97_codec,snd_timer,snd_pcm,snd_seq,snd_rawmidi,snd_ens1371,snd_seq_device
btrtl 16384 1 btusb
btbcm 16384 1 btusb
btintel 16384 1 btusb
drm 360448 6 ttm,drm_kms_helper,vmwgfx
soundcore 16384 1 snd
vmw_vmci 65536 0
i2c_piix4 24576 0
shpchp 36864 0
nfit 32768 0
rfcomm 69632 8
bnep 20480 2
8250_fintek 16384 0
bluetooth 512000 25 bnep,btbcm,btrtl,btusb,rfcomm,btintel
binfmt_misc 20480 1
mac_hid 16384 0
parport_pc 32768 0
ppdev 20480 0
lp 20480 0
parport 49152 3 lp,ppdev,parport_pc
hid_generic 16384 0
usbhid 49152 0
hid 118784 2 hid_generic,usbhid
psmouse 126976 0
mptspi 24576 2
mptscsih 40960 1 mptspi
mptbase 98304 2 mptspi,mptscsih
ahci 36864 0
libahci 32768 1 ahci
e1000 131072 0
scsi_transport_spi 32768 1 mptspi
pata_acpi 16384 0
root@ubuntu:~/Desktop# rmmod ./hello.ko
root@ubuntu:~/Desktop# lsmod
Module Size Used by
coretemp 16384 0
crct10dif_pclmul 16384 0
crc32_pclmul 16384 0
aesni_intel 167936 0
snd_ens1371 28672 0
snd_ac97_codec 131072 1 snd_ens1371
aes_x86_64 20480 1 aesni_intel
gameport 16384 1 snd_ens1371
ac97_bus 16384 1 snd_ac97_codec
vmw_balloon 16384 0
lrw 16384 1 aesni_intel
gf128mul 16384 1 lrw
glue_helper 16384 1 aesni_intel
ablk_helper 16384 1 aesni_intel
snd_pcm 102400 2 snd_ac97_codec,snd_ens1371
cryptd 20480 2 aesni_intel,ablk_helper
snd_seq_midi 16384 0
snd_seq_midi_event 16384 1 snd_seq_midi
input_leds 16384 0
joydev 20480 0
serio_raw 16384 0
snd_rawmidi 32768 2 snd_ens1371,snd_seq_midi
snd_seq 69632 2 snd_seq_midi_event,snd_seq_midi
vmwgfx 172032 3
snd_seq_device 16384 3 snd_seq,snd_rawmidi,snd_seq_midi
ttm 94208 1 vmwgfx
snd_timer 32768 2 snd_pcm,snd_seq
btusb 45056 0
drm_kms_helper 126976 1 vmwgfx
snd 81920 7 snd_ac97_codec,snd_timer,snd_pcm,snd_seq,snd_rawmidi,snd_ens1371,snd_seq_device
btrtl 16384 1 btusb
btbcm 16384 1 btusb
btintel 16384 1 btusb
drm 360448 6 ttm,drm_kms_helper,vmwgfx
soundcore 16384 1 snd
vmw_vmci 65536 0
i2c_piix4 24576 0
shpchp 36864 0
nfit 32768 0
rfcomm 69632 8
bnep 20480 2
8250_fintek 16384 0
bluetooth 512000 25 bnep,btbcm,btrtl,btusb,rfcomm,btintel
binfmt_misc 20480 1
mac_hid 16384 0
parport_pc 32768 0
ppdev 20480 0
lp 20480 0
parport 49152 3 lp,ppdev,parport_pc
hid_generic 16384 0
usbhid 49152 0
hid 118784 2 hid_generic,usbhid
psmouse 126976 0
mptspi 24576 2
mptscsih 40960 1 mptspi
mptbase 98304 2 mptspi,mptscsih
ahci 36864 0
libahci 32768 1 ahci
e1000 131072 0
scsi_transport_spi 32768 1 mptspi
pata_acpi 16384 0
root@ubuntu:~/Desktop# rmmod ./hello.ko
rmmod: ERROR: Module hello is not currently loaded
root@ubuntu:~/Desktop# lsmod
Module Size Used by
coretemp 16384 0
crct10dif_pclmul 16384 0
crc32_pclmul 16384 0
aesni_intel 167936 0
snd_ens1371 28672 0
snd_ac97_codec 131072 1 snd_ens1371
aes_x86_64 20480 1 aesni_intel
gameport 16384 1 snd_ens1371
ac97_bus 16384 1 snd_ac97_codec
vmw_balloon 16384 0
lrw 16384 1 aesni_intel
gf128mul 16384 1 lrw
glue_helper 16384 1 aesni_intel
ablk_helper 16384 1 aesni_intel
snd_pcm 102400 2 snd_ac97_codec,snd_ens1371
cryptd 20480 2 aesni_intel,ablk_helper
snd_seq_midi 16384 0
snd_seq_midi_event 16384 1 snd_seq_midi
input_leds 16384 0
joydev 20480 0
serio_raw 16384 0
snd_rawmidi 32768 2 snd_ens1371,snd_seq_midi
snd_seq 69632 2 snd_seq_midi_event,snd_seq_midi
vmwgfx 172032 3
snd_seq_device 16384 3 snd_seq,snd_rawmidi,snd_seq_midi
ttm 94208 1 vmwgfx
snd_timer 32768 2 snd_pcm,snd_seq
btusb 45056 0
drm_kms_helper 126976 1 vmwgfx
snd 81920 7 snd_ac97_codec,snd_timer,snd_pcm,snd_seq,snd_rawmidi,snd_ens1371,snd_seq_device
btrtl 16384 1 btusb
btbcm 16384 1 btusb
btintel 16384 1 btusb
drm 360448 6 ttm,drm_kms_helper,vmwgfx
soundcore 16384 1 snd
vmw_vmci 65536 0
i2c_piix4 24576 0
shpchp 36864 0
nfit 32768 0
rfcomm 69632 8
bnep 20480 2
8250_fintek 16384 0
bluetooth 512000 25 bnep,btbcm,btrtl,btusb,rfcomm,btintel
binfmt_misc 20480 1
mac_hid 16384 0
parport_pc 32768 0
ppdev 20480 0
lp 20480 0
parport 49152 3 lp,ppdev,parport_pc
hid_generic 16384 0
usbhid 49152 0
hid 118784 2 hid_generic,usbhid
psmouse 126976 0
mptspi 24576 2
mptscsih 40960 1 mptspi
mptbase 98304 2 mptspi,mptscsih
ahci 36864 0
libahci 32768 1 ahci
e1000 131072 0
scsi_transport_spi 32768 1 mptspi
pata_acpi 16384 0
root@ubuntu:~/Desktop# insmod ./hello.ko
root@ubuntu:~/Desktop# tail /var/log/kern.log
Aug 26 07:31:10 ubuntu kernel: [ 1602.408792] the process is"1383225440"(pid 3571)
Aug 26 07:32:39 ubuntu kernel: [ 1691.260987] Bye, kernel!
Aug 26 07:33:50 ubuntu kernel: [ 1762.382921] the process is"1656784352"(pid 3890)
Aug 26 07:54:13 ubuntu kernel: [ 2984.808053] e1000: eth0 NIC Link is Down
Aug 26 07:54:17 ubuntu kernel: [ 2988.809018] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
Aug 26 08:04:09 ubuntu kernel: [ 3580.921624] Bye, kernel!
Aug 26 08:04:11 ubuntu kernel: [ 3583.102812] hello: unknown parameter 'howmany' ignored
Aug 26 08:04:11 ubuntu kernel: [ 3583.102818] hello: unknown parameter 'whom' ignored
Aug 26 08:04:11 ubuntu kernel: [ 3583.106649] the process is"1514516256"(pid 3973)
Aug 26 09:43:32 ubuntu kernel: [ 9544.684133] Bye, kernel!
root@ubuntu:~/Desktop# rmmod ./hello.ko
root@ubuntu:~/Desktop# make
make -C /lib/modules/4.2.0-27-generic/build M=/root/Desktop
make[1]: Entering directory `/usr/src/linux-headers-4.2.0-27-generic'
CC [M] /root/Desktop/hello.o
Building modules, stage 2.
MODPOST 1 modules
CC /root/Desktop/hello.mod.o
LD [M] /root/Desktop/hello.ko
make[1]: Leaving directory `/usr/src/linux-headers-4.2.0-27-generic'
root@ubuntu:~/Desktop# insmod ./hello.ko
root@ubuntu:~/Desktop# tail /var/log/kern.log
Aug 26 07:32:39 ubuntu kernel: [ 1691.260987] Bye, kernel!
Aug 26 07:33:50 ubuntu kernel: [ 1762.382921] the process is"1656784352"(pid 3890)
Aug 26 07:54:13 ubuntu kernel: [ 2984.808053] e1000: eth0 NIC Link is Down
Aug 26 07:54:17 ubuntu kernel: [ 2988.809018] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
Aug 26 08:04:09 ubuntu kernel: [ 3580.921624] Bye, kernel!
Aug 26 08:04:11 ubuntu kernel: [ 3583.102812] hello: unknown parameter 'howmany' ignored
Aug 26 08:04:11 ubuntu kernel: [ 3583.102818] hello: unknown parameter 'whom' ignored
Aug 26 08:04:11 ubuntu kernel: [ 3583.106649] the process is"1514516256"(pid 3973)
Aug 26 09:43:32 ubuntu kernel: [ 9544.684133] Bye, kernel!
Aug 26 09:45:34 ubuntu kernel: [ 9666.366106] haha!!!!
root@ubuntu:~/Desktop# make
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