Linux embedded Learning-Smoke sensor driver-character device driver-key driver

The MQ-2 Smoke gas sensor module is driven on the X210v3 Development Board.

It is now necessary to drive a MQ-2 smoke gas sensor module. After detecting smoke exceeding a certain standard, it will return a different level, similar to the key driver.

But when writing the driver, you need to use the Gph2_3 number PIN. However, the Ioremap address is then configured in the kernel, and it is not possible to control the GPIO or enter the interrupt.

It was later discovered that if you need to use a gpio, you need to apply before you can use it.

The specific procedures are as follows:

#include <linux/module.h>#include<linux/init.h>#include<linux/miscdevice.h>#include<linux/interrupt.h>#include<linux/io.h>#include<linux/fs.h>#include<linux/slab.h>#include<asm/irq.h>#include<linux/random.h>#include<linux/uaccess.h>#include<linux/device.h>#include<mach/gpio.h>#defineGph2con 0XE0200C60#defineGph2dat 0XE0200C64Static struct class*fog_class;//Create ClassStatic structClass_device *fog_class_devs;//Create a device for a classstructWork_struct *Work1;structtimer_list fogs_timer;unsignedint*gpio_data;unsignedintFog_num =0; wait_queue_head_t fog_q;voidWork1_func (structWork_struct *Work ) {Mod_timer (&fogs_timer, Jiffies + (HZ/Ten));}voidFogs_timer_function (unsignedLongdata) {unsignedintFog_val; Fog_val= Readw (gpio_data) &0x08; if(Fog_val = =0) {Fog_num=1; PRINTK ("Press down\n"); } wake_up (&fog_q);} Irqreturn_t Fog_int (intIrqvoid*dev_id)    {schedule_work (WORK1); //return 0;    returnirq_handled;}voidFog_hw_init () {unsignedint*Gpio_config; unsigned Shortdata; Gpio_request (S5PV210_GPH2 (3),"My_fog"); Gpio_config= Ioremap (Gph2con,4); Data=READW (gpio_config); Data&= ~ (0b1111<< A); Data|= 0b1111<< A;    Writew (Data,gpio_config); Gpio_data= Ioremap (Gph2dat,1);}intFog_open (structInode *node,structFile *Filp) {    return 0;} ssize_t Fog_read (structFile *filp,Char__user *buf, size_t size, loff_t *POS)   {wait_event (fog_q,fog_num); //PRINTK ("in Kernel:fog num is%d\n", fog_num);Copy_to_user (buf,&fog_num,4); Fog_num=0; return 4;}structFile_operations Fog_fops ={. Open=Fog_open,. Read=Fog_read,};structMiscdevice Fog_miscdev ={. Minor= $,. Name="Fog",. FoPs= &Fog_fops,};intMajor;Static intFog_init () {intret; Major= Register_chrdev (0,"Fog_drv", &fog_fops); Fog_class= Class_create (This_module,"Fog_class"); Fog_class_devs= Device_create (Fog_class,null,mkdev (Major,0), NULL,"My_fog"); if(Ret! =0) PRINTK ("Register fail!\n"); //X￠2á? D???? Àí3ìdòRequest_irq (Irq_eint ( -), Fog_int,irqf_trigger_falling,"Fog",0); //°?? Ü3?ê?? ˉtFog_hw_init (); //. ???? 1€x÷Work1= Kmalloc (sizeof(structwork_struct), Gfp_kernel);    Init_work (Work1, Work1_func); /*3?ê?? ˉt?? ʱ?÷*/Init_timer (&Fogs_timer); Fogs_timer.function=fogs_timer_function; /*? Ò?úo?x￠2áò????? ʱ?÷*/Add_timer (&Fogs_timer); /*3?ê?? ˉμè?y?óád*/Init_waitqueue_head (&fog_q); return 0;}Static voidFog_exit () {Del_timer (&Fogs_timer); Unregister_chrdev (Major,"Fog_drv" );    Device_unregister (Fog_class_devs); Class_destroy (Fog_class);} Module_init (Fog_init); Module_exit (Fog_exit); Module_license ("GPL");

Linux embedded Learning-Smoke sensor driver-character device driver-key driver