Linux Platform裝置驅動學習與小結

標籤：led驅動   platfrom裝置驅動   

Platform 裝置先被註冊然後platfrom驅動載入時會調用驅動程式中的probe（）入口函數，掃描系統中登入的裝置，通過。Name域找到匹配裝置後將驅動和裝置綁定。一個驅動可以對應多個裝置，但是一個裝置只對一個驅動。Linux下的虛擬匯流排platform對應裝置platform_device，對應的驅動為platform_driver。一個很不恰當的例子：裝置好比男人，驅動好比女人，platform作為媒人，將兩個對上眼的（name域相同）的相匹配到一起。然後男人（device）到她（driver）的門口（driver的probe入口函數）主動去找女人約會巴拉巴拉啪啪啪。。。哎呀好羞射，這就進入正題：

/********************************************************************************* *      Copyright:  (C) 2011 Guo Wenxue<[email protected]>   *                  All rights reserved. * *       Filename:  s3c_led.c *    Description:  This is the common LED driver runs on S3C24XX. *                  *        Version:  1.0.0(10/27/2011~) *         Author:  Guo Wenxue <[email protected]> *      ChangeLog:  1, Release initial version on "10/27/2011 11:39:10 AM" *                  ********************************************************************************/#include "s3c_driver.h"#define DRV_AUTHOR                "Guo Wenxue <[email protected]>"#define DRV_DESC                  "S3C24XX LED driver"/* Driver version*/#define DRV_MAJOR_VER             1#define DRV_MINOR_VER             0#define DRV_REVER_VER             0#define DEV_NAME                  DEV_LED_NAME//#define DEV_MAJOR                 DEV_LED_MAJOR#ifndef DEV_MAJOR#define DEV_MAJOR                 0 /*  dynamic major by default */ #endif#define TIMER_TIMEOUT             40static int debug = DISABLE;static int dev_major = DEV_MAJOR;static int dev_minor = 0;/* ============================ Platform Device part ===============================*//*  LED hardware informtation structure*/struct s3c_led_info{    unsigned char           num;              /* The LED number  */    unsigned int            gpio;             /* Which GPIO the LED used */      unsigned char           active_level;     /* The GPIO pin level(HIGHLEVEL or LOWLEVEL) to turn on or off  */    unsigned char           status;           /* Current LED status: OFF/ON */    unsigned char           blink;            /* Blink or not */           };/*  The LED platform device private data structure */struct s3c_led_platform_data{    struct s3c_led_info    *leds;    int                     nleds;};/*  LED hardware informtation data*/ static struct s3c_led_info  s3c_leds[] = {    [0] = {        .num = 1,        .gpio = S3C2410_GPB(5),        .active_level = LOWLEVEL,        .status = OFF,        .blink = ENABLE,    },    [1] = {        .num = 2,        .gpio = S3C2410_GPB(6),        .active_level = LOWLEVEL,        .status = OFF,        .blink = DISABLE,    },    [2] = {        .num = 3,        .gpio = S3C2410_GPB(8),        .active_level = LOWLEVEL,        .status = OFF,        .blink = DISABLE,    },    [3] = {         .num = 4,        .gpio = S3C2410_GPB(10),        .active_level = LOWLEVEL,        .status = OFF,        .blink = DISABLE,    }, };/*  The LED platform device private data */static struct s3c_led_platform_data s3c_led_data = {    .leds = s3c_leds,    .nleds = ARRAY_SIZE(s3c_leds),};struct led_device{    struct s3c_led_platform_data    *data;    struct cdev                     cdev;    struct class                    *dev_class;    struct timer_list               blink_timer;} led_device;static void platform_led_release(struct device * dev){    int i;    struct s3c_led_platform_data *pdata = dev->platform_data;     dbg_print("%s():%d\n", __FUNCTION__,__LINE__);    /* Turn all LED off */    for(i=0; i<pdata->nleds; i++)    {         s3c2410_gpio_setpin(pdata->leds[i].gpio, ~pdata->leds[i].active_level);     }}static struct platform_device s3c_led_device = {    .name    = "s3c_led",    .id      = 1,    .dev     =     {        .platform_data = &s3c_led_data,         .release = platform_led_release,    },};/* ===================== led device driver part ===========================*/void led_timer_handler(unsigned long data){     int  i;     struct s3c_led_platform_data *pdata = (struct s3c_led_platform_data *)data;    for(i=0; i<pdata->nleds; i++)     {         if(ON == pdata->leds[i].status)        {              s3c2410_gpio_setpin(pdata->leds[i].gpio, pdata->leds[i].active_level);         }        else        {              s3c2410_gpio_setpin(pdata->leds[i].gpio, ~pdata->leds[i].active_level);         }        if(ENABLE == pdata->leds[i].blink )  /* LED should blink */        {            /* Switch status between 0 and 1 to turn LED ON or off */            pdata->leds[i].status = pdata->leds[i].status ^ 0x01;          }        mod_timer(&(led_device.blink_timer), jiffies + TIMER_TIMEOUT);    }}static int led_open(struct inode *inode, struct file *file){     struct led_device *pdev ;    struct s3c_led_platform_data *pdata;    pdev = container_of(inode->i_cdev,struct led_device, cdev);    pdata = pdev->data;    file->private_data = pdata;    return 0;}static int led_release(struct inode *inode, struct file *file){     return 0;}static void print_led_help(void){    printk("Follow is the ioctl() command for LED driver:\n");    printk("Enable Driver debug command: %u\n", SET_DRV_DEBUG);    printk("Get Driver verion  command : %u\n", GET_DRV_VER);    printk("Turn LED on command        : %u\n", LED_ON);    printk("Turn LED off command       : %u\n", LED_OFF);    printk("Turn LED blink command     : %u\n", LED_BLINK);}/* compatible with kernel version >=2.6.38*/static long led_ioctl(struct file *file, unsigned int cmd, unsigned long arg){     struct s3c_led_platform_data *pdata = file->private_data;    switch (cmd)    {        case SET_DRV_DEBUG:            dbg_print("%s driver debug now.\n", DISABLE == arg ? "Disable" : "Enable");            debug = (0==arg) ? DISABLE : ENABLE;            break;        case GET_DRV_VER:            print_version(DRV_VERSION);            return DRV_VERSION;        case LED_OFF:            if(pdata->nleds <= arg)            {               printk("LED%ld doesn't exist\n", arg);                 return -ENOTTY;            }            pdata->leds[arg].status = OFF;            pdata->leds[arg].blink = DISABLE;            break;        case LED_ON:            if(pdata->nleds <= arg)            {               printk("LED%ld doesn't exist\n", arg);                 return -ENOTTY;            }            pdata->leds[arg].status = ON;            pdata->leds[arg].blink = DISABLE;            break;        case LED_BLINK:            if(pdata->nleds <= arg)            {               printk("LED%ld doesn't exist\n", arg);                 return -ENOTTY;            }            pdata->leds[arg].blink = ENABLE;            pdata->leds[arg].status = ON;            break;        default:             dbg_print("%s driver don't support ioctl command=%d\n", DEV_NAME, cmd);             print_led_help();            return -EINVAL;    }    return 0;}static struct file_operations led_fops = {     .owner = THIS_MODULE,     .open = led_open,     .release = led_release,     .unlocked_ioctl = led_ioctl, /* compatible with kernel version >=2.6.38*/};static int s3c_led_probe(struct platform_device *dev){    struct s3c_led_platform_data *pdata = dev->dev.platform_data;     int result = 0;    int i;    dev_t devno;    /* Initialize the LED status */    for(i=0; i<pdata->nleds; i++)    {         s3c2410_gpio_cfgpin(pdata->leds[i].gpio, S3C2410_GPIO_OUTPUT);         if(ON == pdata->leds[i].status)         {            s3c2410_gpio_setpin(pdata->leds[i].gpio, pdata->leds[i].active_level);          }         else         {            s3c2410_gpio_setpin(pdata->leds[i].gpio, ~pdata->leds[i].active_level);          }    }    /*  Alloc the device for driver */    if (0 != dev_major)     {         devno = MKDEV(dev_major, dev_minor);         result = register_chrdev_region(devno, 1, DEV_NAME);     }     else     {         result = alloc_chrdev_region(&devno, dev_minor, 1, DEV_NAME);         dev_major = MAJOR(devno);     }    /* Alloc for device major failure */     if (result < 0)     {         printk("%s driver can't get major %d\n", DEV_NAME, dev_major);         return result;     }    /* Initialize button structure and register cdev*/    memset(&led_device, 0, sizeof(led_device));    led_device.data = dev->dev.platform_data;    cdev_init (&(led_device.cdev), &led_fops);    led_device.cdev.owner  = THIS_MODULE;    result = cdev_add (&(led_device.cdev), devno , 1);     if (result)     {         printk (KERN_NOTICE "error %d add %s device", result, DEV_NAME);         goto ERROR;     }         led_device.dev_class = class_create(THIS_MODULE, DEV_NAME);     if(IS_ERR(led_device.dev_class))     {         printk("%s driver create class failture\n",DEV_NAME);         result =  -ENOMEM;         goto ERROR;     }#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)         device_create(led_device.dev_class, NULL, devno, NULL, DEV_NAME);#else    device_create (led_device.dev_class, NULL, devno, DEV_NAME);#endif    /*  Initial the LED blink timer */    init_timer(&(led_device.blink_timer));    led_device.blink_timer.function = led_timer_handler;    led_device.blink_timer.data = (unsigned long)pdata;    led_device.blink_timer.expires  = jiffies + TIMER_TIMEOUT;    add_timer(&(led_device.blink_timer));     printk("S3C %s driver version %d.%d.%d initiliazed.\n", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);     return 0;               ERROR:     printk("S3C %s driver version %d.%d.%d install failure.\n", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);     cdev_del(&(led_device.cdev));     unregister_chrdev_region(devno, 1);     return result;}static int s3c_led_remove(struct platform_device *dev){    dev_t devno = MKDEV(dev_major, dev_minor);    del_timer(&(led_device.blink_timer));    cdev_del(&(led_device.cdev));     device_destroy(led_device.dev_class, devno);     class_destroy(led_device.dev_class);         unregister_chrdev_region(devno, 1);     printk("S3C %s driver removed\n", DEV_NAME);    return 0;}static struct platform_driver s3c_led_driver = {     .probe      = s3c_led_probe,     .remove     = s3c_led_remove,     .driver     = {         .name       = "s3c_led",         .owner      = THIS_MODULE,     },};static int __init s3c_led_init(void){   int       ret = 0;   ret = platform_device_register(&s3c_led_device);   if(ret)   {        printk(KERN_ERR "%s:%d: Can't register platform device %d\n", __FUNCTION__,__LINE__, ret);         goto fail_reg_plat_dev;   }   dbg_print("Regist S3C LED Platform Device successfully.\n");   ret = platform_driver_register(&s3c_led_driver);   if(ret)   {        printk(KERN_ERR "%s:%d: Can't register platform driver %d\n", __FUNCTION__,__LINE__, ret);         goto fail_reg_plat_drv;   }   dbg_print("Regist S3C LED Platform Driver successfully.\n");   return 0;fail_reg_plat_drv:   platform_driver_unregister(&s3c_led_driver);fail_reg_plat_dev:   return ret;}static void s3c_led_exit(void){    dbg_print("%s():%d remove LED platform drvier\n", __FUNCTION__,__LINE__);    platform_driver_unregister(&s3c_led_driver);    dbg_print("%s():%d remove LED platform device\n", __FUNCTION__,__LINE__);    platform_device_unregister(&s3c_led_device);}module_init(s3c_led_init);module_exit(s3c_led_exit);module_param(debug, int, S_IRUGO);module_param(dev_major, int, S_IRUGO);module_param(dev_minor, int, S_IRUGO);MODULE_AUTHOR(DRV_AUTHOR);MODULE_DESCRIPTION(DRV_DESC);MODULE_LICENSE("GPL");MODULE_ALIAS("platform:S3C24XX_led");

學習驅動後的小結：

一、

static struct platform_device s3c_led_device = {

    .name    = "s3c_led",

    .id      = 1,

    .dev     =

    {

        .platform_data = &s3c_led_data,

        .release = platform_led_release,

    },

};

 

static struct platform_driver s3c_led_driver = {

    .probe      = s3c_led_probe,  

    .remove     = s3c_led_remove,

    .driver     = {

        .name       = "s3c_led",

        .owner      = THIS_MODULE,

    },

};

注意：驅動和裝置的結構體成員有差別，但是用來匹配識別的name域卻是相同的。只有這樣才能實現互相匹配，實現驅動找裝置，裝置找驅動的互找。

二、

首先載入驅動時調用s3c_led_init（）函數分別註冊platfrom裝置和platfrom驅動。

 

而對於platfrom_devices裝置鏈來說:

Platfrom_device_register -> 調用（platform_device）結構體類型的結構體s3c_led_device，結構體中定義name域和id以及裝置dev資訊的函數指標，其中 -> 裝置資料又存放在結構體類型為（s3c_led_platform_data）的結構體變數s3c_led_data中 -> s3c_led_data成員leds函數指標指向s3c_led_info結構體類型的s3c_leds結構體數組中。nleds函數指標指向一個核心中的宏定義ARRAY_SIZE（），可以求出裝置的個數。

對於platfrom_driver 驅動鏈來說：

Platfrom_driver_register -> 調用（platform_driver）結構體類型的結構體s3c_led_driver，結構體中有指向s3c_led_probe的probe指標和remove指標以及driver指標 -> 載入驅動鏈調用了s3c_led_driver結構體變數後首先便會調用s3c_led_probe函數。而probe函數的參數是platform_device結構體類型的指標。 -> 其中首先定義了一個s3c_led_platfrom_data類型的指標擷取裝置的資訊。然後依次更改LED燈gpio口的狀態以及通過判斷主裝置號靜態或者動態擷取裝置號。 -> 初始化cdev結構體，並且將fops結構體與之綁定。字元裝置驅動註冊

Linux Platform裝置驅動學習與小結