1//development/ndk/platforms/android-30/include/sys/ioctl.h
2int ioctl(int fd, int cmd, ...) ;

 1//kernel/include/uapi/asm-generic/unistd.h
 2#ifndef __SYSCALL
 3#define __SYSCALL(x, y)
 4#endif
 5
 6#if __BITS_PER_LONG == 32 || defined(__SYSCALL_COMPAT)
 7#define __SC_3264(_nr, _32, _64) __SYSCALL(_nr, _32)
 8#else
 9#define __SC_3264(_nr, _32, _64) __SYSCALL(_nr, _64)
10#endif
11
12#ifdef __SYSCALL_COMPAT
13#define __SC_COMP(_nr, _sys, _comp) __SYSCALL(_nr, _comp)
14#define __SC_COMP_3264(_nr, _32, _64, _comp) __SYSCALL(_nr, _comp)
15#else
16#define __SC_COMP(_nr, _sys, _comp) __SYSCALL(_nr, _sys)
17#define __SC_COMP_3264(_nr, _32, _64, _comp) __SC_3264(_nr, _32, _64)
18#endif
19
20/* fs/ioctl.c */
21#define __NR_ioctl 29
22__SC_COMP(__NR_ioctl, sys_ioctl, compat_sys_ioctl)

1//kernel/include/uapi/asm-generic/unistd.h
2__SYSCALL(29, sys_ioctl)

1//kernel/arch/arc/kernel/sys.c
2#define __SYSCALL(nr, call) [nr] = (call),
3
4void* sys_call_table[NR_syscalls] = {
5    [0 ... NR_syscalls - 1] = sys_ni_syscall,
6    #include<asm/unistd.h>
7};

1int my_array[6] = { [4] = 29, [2] = 15 };
2//或者写成：
3//省略到索引与值之间的=，GCC 2.5 之后该用法已经过时了，但 GCC 仍然支持
4int my_array[6] = { [4] 29, [2] 15 };     
5//两者均等价于：
6int my_array[6] = {0, 0, 15, 0, 29, 0};

 1//所以得到的ioctl函数就是下面这个宏定义
 2__SYSCALL(0, sys_io_setup)
 3__SYSCALL(1, sys_io_destroy)
 4__SYSCALL(2, sys_io_submit)
 5...
 6__SYSCALL(29, sys_ioctl)
 7...
 8//展开上述的宏定义
 9[0] = sys_io_setup,
10[1] = sys_io_destroy,
11[2] = sys_io_submit,
12...
13[29] = sys_ioctl,
14...

 1//kernel/arch/arc/kernel/sys.c
 2#define __SYSCALL(nr, call) [nr] = (call),
 3
 4void* sys_call_table[435] = {
 5    [0 ... 434] = sys_ni_syscall,
 6    [0] = sys_restart_syscall,
 7    [1] = sys_exit,
 8    [2] = sys_fork,
 9    ...
10    [29] = sys_ioctl,
11    ...
12};

1//kernel/include/linux/syscalls.h
2asmlinkage long sys_ioctl(unsigned int fd, unsigned int cmd, unsigned long long);

 1//kernel/fs/ioctl.c
 2//实际上SYSCALL_DEFINE3就是sys_ioctl
 3SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 4{
 5	struct file *filp;
 6	int error = -EBADF;
 7	int fput_needed;
 8
 9	filp = fget_light(fd, &fput_needed);//由fd得带filp指针
10	if (!filp)
11		goto out;
12
13	error = security_file_ioctl(filp, cmd, arg);
14	if (error)
15		goto out_fput;
16
17	error = do_vfs_ioctl(filp, fd, cmd, arg);
18 out_fput:
19	fput_light(filp, fput_needed);
20 out:
21	return error;
22}

 1//kernel/fs/ioctl.c
 2int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
 3	     unsigned long arg)
 4{
 5	int error = 0;
 6	int __user *argp = (int __user *)arg;
 7	struct inode *inode = filp->f_path.dentry->d_inode;
 8
 9	switch (cmd) {
10	case FIOCLEX:
11		set_close_on_exec(fd, 1);
12		break;
13
14	case FIONCLEX:
15		set_close_on_exec(fd, 0);
16		break;
17
18	case FIONBIO:
19		error = ioctl_fionbio(filp, argp);
20		break;
21
22	case FIOASYNC:
23		error = ioctl_fioasync(fd, filp, argp);
24		break;
25
26	case FIOQSIZE:
27		if (S_ISDIR(inode->i_mode) || S_ISREG(inode->i_mode) ||
28		    S_ISLNK(inode->i_mode)) {
29			loff_t res = inode_get_bytes(inode);
30			error = copy_to_user(argp, &res, sizeof(res)) ?
31					-EFAULT : 0;
32		} else
33			error = -ENOTTY;
34		break;
35
36	case FIFREEZE:
37		error = ioctl_fsfreeze(filp);
38		break;
39
40	case FITHAW:
41		error = ioctl_fsthaw(filp);
42		break;
43
44	case FS_IOC_FIEMAP:
45		return ioctl_fiemap(filp, arg);
46
47	case FIGETBSZ:
48		return put_user(inode->i_sb->s_blocksize, argp);
49
50	default:
51		if (S_ISREG(inode->i_mode))//是否为常规文件若是常规文件
52			error = file_ioctl(filp, cmd, arg);
53		else
54			error = vfs_ioctl(filp, cmd, arg);//调用vfs_ioctl
55		break;
56	}
57	return error;
58}

 1//kernel/include/linux/fs.h
 2struct inode {
 3	umode_t			i_mode;
 4	unsigned short		i_opflags;
 5	kuid_t			i_uid;
 6	kgid_t			i_gid;
 7	unsigned int		i_flags;
 8
 9	const struct inode_operations	*i_op;
10	struct super_block	*i_sb;
11	struct address_space	*i_mapping;
12
13	unsigned long		i_ino;
14	union {
15		const unsigned int i_nlink;
16		unsigned int __i_nlink;
17	};
18	dev_t			i_rdev;
19	loff_t			i_size;
20	struct timespec64	i_atime;
21	struct timespec64	i_mtime;
22	struct timespec64	i_ctime;
23	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */
24	unsigned short          i_bytes;
25	u8			i_blkbits;
26	u8			i_write_hint;
27	blkcnt_t		i_blocks;
28
29	/* Misc */
30	unsigned long		i_state;
31	struct rw_semaphore	i_rwsem;
32
33	unsigned long		dirtied_when;	/* jiffies of first dirtying */
34	unsigned long		dirtied_time_when;
35
36	struct hlist_node	i_hash;
37	struct list_head	i_io_list;	/* backing dev IO list */
38#ifdef CONFIG_CGROUP_WRITEBACK
39	struct bdi_writeback	*i_wb;		/* the associated cgroup wb */
40
41	/* foreign inode detection, see wbc_detach_inode() */
42	int			i_wb_frn_winner;
43	u16			i_wb_frn_avg_time;
44	u16			i_wb_frn_history;
45#endif
46	struct list_head	i_lru;		/* inode LRU list */
47	struct list_head	i_sb_list;
48	struct list_head	i_wb_list;	/* backing dev writeback list */
49	union {
50		struct hlist_head	i_dentry;
51		struct rcu_head		i_rcu;
52	};
53	atomic64_t		i_version;
54	atomic64_t		i_sequence; /* see futex */
55	atomic_t		i_count;
56	atomic_t		i_dio_count;
57	atomic_t		i_writecount;
58	union {
59		const struct file_operations	*i_fop;	/* former ->i_op->default_file_ops */
60		void (*free_inode)(struct inode *);
61	};
62	struct file_lock_context	*i_flctx;
63	struct address_space	i_data;
64	struct list_head	i_devices;
65	union {
66		struct pipe_inode_info	*i_pipe;
67		struct cdev		*i_cdev;
68		char			*i_link;
69		unsigned		i_dir_seq;
70	};
71
72	__u32			i_generation;
73
74	void			*i_private; /* fs or device private pointer */
75} __randomize_layout;

 1//kernel/include/uapi/asm-generic/stat.h
 2struct stat {
 3	unsigned long	st_dev;		 //文件的设备编号
 4	unsigned long	st_ino;		 //节点
 5	unsigned int	st_mode;	//文件的类型和存取的权限
 6	unsigned int	st_nlink;	 //连到该文件的硬连接数目，刚建立的文件值为1
 7	unsigned int	st_uid;		 //用户ID
 8	unsigned int	st_gid;		  //组ID
 9	unsigned long	st_rdev;	 //(设备类型)若此文件为设备文件，则为其设备编号
10	unsigned long	__pad1;
11	long		st_size;	//文件字节数(文件大小)
12	int		st_blksize;	 //块大小(文件系统的I/O 缓冲区大小)
13	int		__pad2;
14	long		st_blocks;	 //块数
15	long		st_atime;	 //最后一次访问时间
16	unsigned long	st_atime_nsec;
17	long		st_mtime;	 //最后一次修改时间
18	unsigned long	st_mtime_nsec;
19	long		st_ctime;	//最后一次改变时间(指属性)
20	unsigned long	st_ctime_nsec;
21	unsigned int	__unused4;
22	unsigned int	__unused5;
23};

 1//kernel/fs/ioctl.c
 2static long vfs_ioctl(struct file *filp, unsigned int cmd,
 3		      unsigned long arg)
 4{
 5	int error = -ENOTTY;
 6
 7	if (!filp->f_op || !filp->f_op->unlocked_ioctl)
 8		goto out;
 9unlocked_ioctl
10	error = filp->f_op->unlocked_ioctl(filp, cmd, arg);//调用unlocked_ioctl()
11	if (error == -ENOIOCTLCMD)
12		error = -EINVAL;
13 out:
14	return error;
15}	

 1//kernel/include/linux/fs.h
 2struct  file_operations { 
 3	struct module * owner;
 4	loff_t (* llseek ) (struct file *, loff_t , int ); 
 5	ssize_t (* read ) (struct file *, char __user *, size_t , loff_t *); 
 6	ssize_t (* write ) (struct file *, const char __user *, size_t , loff_t *); 
 7	ssize_t (*read_iter) (struct kiocb *, struct iov_iter *); 
 8	ssize_t(*write_iter) (struct kiocb *, struct iov_iter *); 
 9	int (*iterate) (struct file *, struct dir_context *); 
10	unsigned int (*poll) (struct file *, struct poll_table_struct *) ; 
11	long (*unlocked_ioctl) (struct file *, unsigned int , unsigned long ); 
12	long (*compat_ioctl) (struct file *, unsigned int , unsigned long ); 
13	int (*mmap) (struct file *, struct vm_area_struct *); 
14	...
15}

1//文件操作集
2struct file_operations misc_fops = {
3    ...
4    .unlocked_ioctl = my_ioctl
5    ...
6};

1//kernel/include/uapi/asm-generic/ioctl.h
2#define _IOC(dir,type,nr,size) \
3    (((dir)  << _IOC_DIRSHIFT) | \
4     ((type) << _IOC_TYPESHIFT) | \
5     ((nr)   << _IOC_NRSHIFT) | \
6     ((size) << _IOC_SIZESHIFT))

 1//kernel/include/uapi/asm-generic/ioctl.h
 2/* used to create numbers */
 3//定义不带参数的 ioctl 命令
 4#define _IO(type,nr)        _IOC(_IOC_NONE,(type),(nr),0)
 5//定义带写参数的 ioctl 命令（copy_from_user）
 6#define _IOR(type,nr,size)  _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
 7//定义带读参数的ioctl命令（copy_to_user）
 8#define _IOW(type,nr,size)  _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
 9//定义带读写参数的 ioctl 命令
10#define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
11
12//内核还提供了反向解析 ioctl 命令的宏接口：
13#define _IOC_DIR(nr)        (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)	//方向
14#define _IOC_TYPE(nr)       (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)	//幻数
15#define _IOC_NR(nr)     (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)			//编号
16#define _IOC_SIZE(nr)       (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)	//大小

 1//external/ioctl_test/ioctl_test.c
 2#include<stdio.h>
 3#include<stdlib.h>
 4#include<fcntl.h>
 5#include<string.h>
 6#include<unistd.h>
 7#include<sys/ioctl.h>
 8
 9#define CMD_TEST_0 _IO('A', 0)
10#define CMD_TEST_1 _IOR('A', 1, int)
11#define CMD_TEST_2 _IOW('A', 2, int)
12#define CMD_TEST_3 _IOWR('A', 3, int)
13
14int main(int argc, char *argv[]){
15    int fd = 0;
16    int revData = 0;
17
18    fd = open("/dev/ioctl_test", O_RDWR);
19    if(fd < 0){
20        printf("open failed\n");
21        exit(1);
22    }
23    printf("open success\n");
24
25    /*依次调用四个命令*/
26    ioctl(fd, CMD_TEST_0);
27    
28    revData = ioctl(fd, CMD_TEST_1);
29    printf("receive 1 data=%d\n", revData);
30
31    ioctl(fd, CMD_TEST_2, 99);
32
33    revData = ioctl(fd, CMD_TEST_3, 101);
34    printf("receive 3 data=%d\n", revData);
35
36    close(fd);
37    return 0;
38}

1//完成misc设备注册。
2int misc_register(struct miscdevice * misc);
3//完成misc设备注销。
4int misc_deregister(struct miscdevice *misc);

  1//kernel/drivers/soc/xxx/sdmmc_ioctl_test.c
  2#include <linux/init.h>
  3#include <linux/module.h>
  4#include <linux/miscdevice.h>
  5#include <linux/fs.h>
  6#include <linux/uaccess.h>
  7#include <linux/io.h>
  8
  9#define CMD_TEST_0 _IO('A', 0)       //不需要读写的命令
 10#define CMD_TEST_1 _IOR('A', 1, int) //从内核读取一个int的命令
 11#define CMD_TEST_2 _IOW('A', 2, int) //向内核写入一个int的命令
 12#define CMD_TEST_3 _IOWR('A', 3, int) //读写一个int的命令
 13
 14int misc_open(struct inode *a,struct file *b){
 15    printk("misc open \n");
 16    return 0;
 17}
 18
 19int misc_release (struct inode * a, struct file * b){
 20    printk("misc file release\n");
 21    return 0;
 22}
 23
 24long my_ioctl(struct file *fd, unsigned int cmd, unsigned long b){
 25    /*将命令按内容分解，打印出来*/
 26    printk("cmd type=(%c)\t nr=(%d)\t dir=(%d)\t size=(%d)\n", _IOC_TYPE(cmd), _IOC_NR(cmd), _IOC_DIR(cmd), _IOC_SIZE(cmd));
 27
 28    /* 检查设备类型 */
 29    if (_IOC_TYPE(cmd) != IOC_MAGIC) {
 30        pr_err("[%s] command type [%c] error!\n", \
 31               __func__, _IOC_TYPE(cmd));
 32        return -ENOTTY; 
 33    }
 34
 35    /* 检查序数 */
 36    if (_IOC_NR(cmd) > IOC_MAXNR) { 
 37        pr_err("[%s] command numer [%d] exceeded!\n", 
 38               __func__, _IOC_NR(cmd));
 39        return -ENOTTY;
 40    }
 41    
 42    /* 检查访问模式 */
 43    if (_IOC_DIR(cmd) & _IOC_READ)
 44        ret= !access_ok(VERIFY_WRITE, (void __user *)arg, \
 45                        _IOC_SIZE(cmd));
 46    else if (_IOC_DIR(cmd) & _IOC_WRITE)
 47        ret= !access_ok(VERIFY_READ, (void __user *)arg, \
 48                        _IOC_SIZE(cmd));
 49    if (ret)
 50        return -EFAULT;
 51
 52    switch(cmd){
 53        case CMD_TEST_0://不需要读写的命令
 54            printk("CMD_TEST_0\n");
 55            break;
 56        case CMD_TEST_1://从内核读取一个int的命令
 57            printk("CMD_TEST_1\n");
 58            return 1;
 59            break;
 60        case CMD_TEST_2://向内核写入一个int的命令
 61            printk("CMD_TEST_2 date=(%d)\n",b);
 62            break;
 63        case CMD_TEST_3://读写一个int的命令
 64            printk("CMD_TEST_3 date=(%d)\n",b);
 65            return b+1;
 66            break;
 67    }
 68
 69    return 0;
 70}
 71
 72//文件操作集
 73struct file_operations misc_fops = {
 74    .owner = THIS_MODULE,
 75    .open = misc_open,
 76    .release = misc_release,
 77    .unlocked_ioctl = my_ioctl
 78    .compat_ioctl = my_ioctl
 79};
 80
 81//ioctl_test，设备节点名,添加了这个语句可以在设备中ls找到这个设备节点，并且是c开头的
 82struct miscdevice misc_dev = {
 83    .minor = MISC_DYNAMIC_MINOR,
 84    .name = "ioctl_test",   
 85    .fops = &misc_fops
 86};
 87
 88//这里的__exit,这是一个宏定义,同下面的__init类似
 89static __exit int ioctl_init(void){
 90    int ret;
 91
 92    ret = misc_register(&misc_dev);  //注册杂项设备
 93    if(ret < 0){
 94        printk("misc regist failed\n");
 95        return -1;
 96    }
 97
 98    printk("misc regist succeed\n");
 99    return 0;
100}
101
102//这里的__init，这是一个宏定义
103//最常用的地方是驱动模块初始化函数的定义处，其目的是将驱动模块的初始化函数放入名叫.init.text的输入段
104static __init void ioctl_exit(void){
105    misc_deregister(&misc_dev);
106}
107
108//下面这两个宏，可以展开
109MODULE_LICENSE("Dual BSD/GPL");
110MODULE_AUTHOR("yangyang48");
111
112//这里可以改成module_init
113device_initcall_sync(ioctl_init); 
114module_exit(ioctl_exit);  

 1/* 检查设备类型 */
 2//这里定义的type是'A'
 3if (_IOC_TYPE(cmd) != IOC_MAGIC) {
 4    pr_err("[%s] command type [%c] error!\n", \
 5           __func__, _IOC_TYPE(cmd));
 6    return -ENOTTY; 
 7}
 8
 9/* 检查序数 */
10//这里定义的序数为4
11if (_IOC_NR(cmd) > IOC_MAXNR) { 
12    pr_err("[%s] command numer [%d] exceeded!\n", 
13           __func__, _IOC_NR(cmd));
14    return -ENOTTY;
15}    
16
17/* 检查访问模式 */
18if (_IOC_DIR(cmd) & _IOC_READ)
19    ret= !access_ok(VERIFY_WRITE, (void __user *)arg, \
20                    _IOC_SIZE(cmd));
21else if (_IOC_DIR(cmd) & _IOC_WRITE)
22    ret= !access_ok(VERIFY_READ, (void __user *)arg, \
23                    _IOC_SIZE(cmd));
24if (ret)
25    return -EFAULT;

1config IOCTL_TEST
2    bool "This is IOCTL_TEST"
3    default y
4    help
5      IOCTL TEST support permissions for users and groups beyond the owner/group/world scheme.
6      If you don't know what Access Control Lists are, say N.

1obj-y += sdmmc_ioctl_test.o
2//可以写成上述的样子
3obj-$(CONFIG_IOCTL_TEST) += sdmmc_ioctl_test.o

1LOCAL_PATH := $(call my-dir)
2include $(CLEAR_VARS)
3LOCAL_MODULE := ioctl_test
4LOCAL_SRC_FILES += ioctl_test.c
5LOCAL_C_INCLUDE += $(LOCAL_PATH)/
6LOCAL_C_FLAG := -Wreturn-local-addr -Wwriting_strings -fpermissive -fexceptions -Wall -Wno-unused-variable -lgcc_s -std=c99
7#编译生成动态文件so
8include $(BUILD_SHARE_LIBRARY)
9include $(call all_makefiles_under, $(LOCAL_PATH))