ARMLinux automatically creates a device Node

Hardware Platform: FL2440 kernel version: 2.6.28 host platform: Ubuntu11.04 kernel version: 2.6.391. First, configure busyboxbusyboxLinuxSystemUtilities --- & gt; [*] mdev [*] Support/etc/mdev. conf & nbsp

Hardware Platform: FL2440

Kernel version: 2.6.28

Host platform: Ubuntu 11.04

Kernel version: 2.6.39

1. Configure busybox first

Busybox
Linux System Utilities --->
[*] Mdev
[*] Support/etc/mdev. conf
[*] Support command execution at device addition/removal

2. Configure the kernel

3. Modify/etc/init. d/rcS in the file system.

Vi./etc/init. d/rcS
Mount-
Mkdir/dev/pts
Mount-t devpts/dev/pts
Echo/sbin/mdev>/proc/sys/kernel/hotplug
Mdev-s

4. Modify/etcfstab

Vi./etc/fstab
# Device mount-point type options dump fsck order
Proc/proc defaults 0 0
Tmpfs/tmp tmpfs defaults 0 0
Sysfs/sys sysfs defaults 0 0
Tmpfs/dev tmpfs defaults 0 0

In this way, you do not need to manually create the device node file when writing the driver.

The following is a modified ADC Driver that uses a Hybrid device. This allows you to automatically create and delete device nodes.

1. # Include
2. # Include
3. # Include
4. # Include /* Create a device node */
5. # Include
6. # Include /* Define DECLARE_WAIT_QUEUE_HEAD */
7. # Include /* Defines irqreturn_t and so on */
8. # Include /* Request_irq disable_irq enable_irq */
9. # Include
10. # Include
11. # Include/* contains # include "mach/irqs. h "*/
12. # Include
13. # Include
14. # Define ADC_MAJOR 102
15. # Define ADC_NAME "my_adc"
16. # Define SUCCESS 0
17. Static IntAdc_open (StructInode *,StructFile *);
18. Static IntAdc_release (StructInode *,StructFile *);
19. Static Int_ Init adc_init (Void);
20. Static Int_ Exit adc_exit (Void);
21. StaticSsize_t adc_read (StructFile *,Char*,Size_t, Loff_t *);
22. VolatileUnsignedLongAdc_con;
23. UnsignedLongAdc_dat0;
24. IntFlag;// Wait for the task to complete
25. UnsignedLongBuf;// Store the converted data
26. // Declare the waiting queue
27. DECLARE_WAIT_QUEUE_HEAD (adc_wait );
28. StructClk * adc_clk;
29. StaticIrqreturn_t adc_interrupt (IntIrq,Void* Dev_id)// Interrupt handling program
30. {
31. If(Flag = 0)
32. {
33. Buf = (readw (adc_dat0) & 0x3ff );// Read the converted data
34. Flag = 1;
35. Wake_up_interruptible (& adc_wait );// Wake up the process waiting for it
36. Printk ("Read value is % ld \ n", Buf );
37. }
38. ReturnIRQ_HANDLED;
39. }
40. Static StructFile_operations adc_ops =
41. {
42. . Owner = THIS_MODULE,
43. . Read = adc_read,
44. . Open = adc_open,
45. . Release = adc_release,
46. };
47. Static StructMiscdevice adc_misc =
48. {
49. . Name = ADC_NAME,
50. . Minor = ADC_MAJOR,
51. . Fops = & adc_ops,
52. };
53. Static Int_ Init adc_init (Void)
54. {
55. IntRet;
56. Adc_clk = clk_get (NULL,"Adc");// Get the clock
57. Clk_enable (adc_clk );// Enable clock
59. Ret = misc_register (& adc_misc );// Register the device
60. If(Ret <0)
61. {
62. Printk ("Register device fail \ n");
63. ReturnRet;
64. }
65. Adc_con = (unsignedLong) Ioremap (0x5821300,4 );
66. Adc_dat0 = (VolatileUnsignedLong) Ioremap (0x58000000 + S3C2410_ADCDAT0, 4 );
67. If(! (Adc_con & adc_dat0 ))
68. {
69. Printk ("Failed to ioremap \ n");
70. GotoHandle;
71. }
72. Printk ("Initialized... \ n");
73. ReturnSUCCESS;
74. Handle:
75. Misc_deregister (& adc_misc );
76. Return-1;
77. }
78. Static IntAdc_open (StructInode * inode,StructFile * file)// Enable the device function
79. {
80. // Registration interrupted
81. IntRet;
82. // Disable_irq (IRQ_ADC );
83. // Enable_irq (IRQ_ADC );
84. Ret = request_irq (IRQ_ADC, adc_interrupt, ir1__shared, ADC_NAME, 1 );// Registration interrupt IRQ_ADC defined in mach/irqs. h
85. If(Ret <0)
86. {
87. Printk ("IRQ % d can not request \ n", IRQ_ADC );
88. ReturnRet;
89. }
90. ReturnSUCCESS;
91. }
92. Static IntAdc_release (StructInode * inode,StructFile * file)// Disable the device function
93. {
94. Free_irq (IRQ_ADC, 1 );// Release interrupted
95. ReturnSUCCESS;
96. }
97. StaticSsize_t adc_read (StructFile * file,
98. Char* Buffer,
99. Size_tLength,
100. Loff_t * offset)// Device read Function
101. {
103. Writew (1 <14) | (0x31 <6), adc_con );// Set ADCCON
104. Writew (readw (adc_con) | 0x1), adc_con );// Start ad ing
105. Wait_event_interruptible (adc_wait, flag );
106. Flag = 0;
107. }
108. Static Int_ Exit adc_exit (Void)// Driver uninstall Function
109. {
110. Iounmap (adc_con );
111. Iounmap (adc_dat0 );
112. Misc_deregister (& adc_misc );
113. Clk_disable (adc_clk );
114. Clk_put (adc_clk );
115. Printk ("The adc is unintialized \ n");
116. ReturnSUCCESS;
117. }
118. Module_init (adc_init );
119. Module_exit (adc_exit );
120. MODULE_LICENSE ("GPL");