Character Device Driver-platform device driver)

How to use the platform device driver to write the driver:
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1. Implement device orientation first:
1) read the chip manual and obtain resources from the schematic diagram.
2) construct a platform device structure and add platform Resources
3) link our device resources to the device connection table of the virtual bus.

2. then implement the device driver:
1) construct a platform-driven structure. When you do not know it, you can view other users'
2) Register and add our drivers to the device driver connection table on the platform.
3) Implement the probe function
4) hardware operations
5) register the character Device Driver

Led_dev.c

# Include <Linux/fs. h> # Include <Linux/module. h> # Include <Linux/errno. h> # Include <Linux/kernel. h> # Include <Linux/init. h> # Include <Linux/cdev. h> # Include <Linux/ioport. h> # Include <Linux/PCI. h> # Include <ASM/uaccess. h> # Include <ASM/IO. h> # Include <ASM/IRQ. h> # Include <Linux/interrupt. h> # Include <ASM/Mach/IRQ. h> # Include <ASM/ARCH/regs-gpio.h> # Include <Linux/poll. h> # Include <Linux/platform_device.h> /* Refer to arch/ARM/plat-s3c24xx/Devs. C */ /* 1. obtain resources according to the chip manual */ StaticStruct ResourceLed_resource [] = { [0] = { . Start = 0x56000050, . End = 0x56000057, . Flags = ioresource_mem, }, [1] = { . Start = 5, . End = 5, . Flags = ioresource_irq, }, }; Void led_release (struct device * Dev) { } /* 1. Construct the device structure of the platform and add platform Resources */ Struct platform_device Led_device = { . Name ="Myled",/* Use the platform driver named" myled */ . ID =-1, . Dev = { . Release = led_release, }, . Num_resources = array_size (led_resource ), . Resource = led_resource, }; /* 2. Link our device resources to the device connection table of the virtual bus */ Int led_dev_init (void) {  Platform_device_register(& Led_device ); Return 0; } Void led_dev_exit (void) {  Platform_device_unregister(& Led_device ); } Module_init (led_dev_init ); Module_exit (led_dev_exit ); Module_license ("GPL ");

Led_drv.c

# Include <Linux/fs. h> # Include <Linux/module. h> # Include <Linux/errno. h> # Include <Linux/kernel. h> # Include <Linux/init. h> # Include <Linux/cdev. h> # Include <Linux/ioport. h> # Include <Linux/PCI. h> # Include <ASM/uaccess. h> # Include <ASM/IO. h> # Include <ASM/IRQ. h> # Include <Linux/interrupt. h> # Include <ASM/Mach/IRQ. h> # Include <ASM/ARCH/regs-gpio.h> # Include <Linux/poll. h> # Include <Linux/platform_device.h> Static int major = 0; Static volatile unsigned long * gpio_con; Static volatile unsigned long * gpio_dat; Static int pin; Static struct class * CLS; Int led_open (struct inode * inode, struct file * file) { /* Set the corresponding pin to the output pin */ * Gpio_con & = ~ (0x3 <(PIN * 2 )); * Gpio_con | = (0x1 <(PIN * 2 ));   Return 0; } Ssize_t led_write (struct file * file, const char _ User * Buf, size_t size, loff_t * offset) { Char ker_buf [1];   /* Input value points/lights out based on Buf */ /* Buf [0]-light/off, 0-light, 1-off */ If (size! = 1) { Return-einval; } Copy_from_user (ker_buf, Buf, 1 );   If (ker_buf [0]! = 0) & (ker_buf [0]! = 1 )) Return-einval; If (ker_buf [0]) { // An LED * Gpio_dat | = (0x1 <pin ); } Else { // An LED * Gpio_dat & = ~ (0x1 <pin ); }   Return 1; } /* 4 hardware operations */ StaticStruct file_operationsLed_fops = { . Owner = this_module, . Open = led_open, . Write = led_write, }; /* 3.Implement the probe function*/ Static intLed_probe(Struct platform_device * Dev) { Struct resource * R;   /* Determine the LED Based on the platform device */ R =Platform_get_resource(Dev, ioresource_mem, 0 ); /* Map resources after obtaining them */ Gpio_con = ioremap (R-> Start, R-> end-r-> Start + 1 ); Gpio_dat = gpio_con + 1; R = platform_get_resource (Dev, ioresource_irq, 0 ); Pin = r-> start; /* Register the driver to register our character device driver in the kernel */ Major =Register_chrdev(0, "led", & led_fops ); /* Sysfs => mount to/sys */ CLS = class_create (this_module, "led_class "); Class_device_create (CLS, null, mkdev (Major, 0), null, "led "); // Mdev creates/dev/LED Based on the content in/sys. Return 0; } IntLed_remove(Struct platform_device * Dev) { Unregister_chrdev (Major, "led "); Class_device_destroy (CLS, mkdev (Major, 0 )); Class_destroy (CLS ); Iounmap (gpio_con ); Return 0; } /* 1. Build a platform-driven struct. When you do not know it, you can view others */ StaticStruct platform_driverLed_driver = { . Probe =Led_probe,/* When a platform device is added under the platform bus, the enumerated function is called */ . Remove =Led_remove,/* When removing a platform device from the platform bus, call the remove function */ . Driver = { . Name ="Myled",/* Supports platform devices named" myled */ . Owner = this_module, }, }; /* 2. Register and add our drivers to the platform device driver connection table */ Static int led_drv_init (void) {  Platform_driver_register(& Led_driver ); Return 0; } Static int led_drv_exit (void) {  Platform_driver_unregister(& Led_driver ); Return 0; } Module_init (led_drv_init ); Module_exit (led_drv_exit ); Module_license ("GPL ");