一個物理設備 - >兩個字符設備

Question

我有一個gpio設備。 我有一個內核模塊來處理這個設備。

//headers 
#include <linux/module.h> 
#include <linux/init.h> 
... 

//declarations 
static si_t *gpio_sih; 
static int gpio_major; 
static struct class *gpiodev_class = NULL; 

//some functions for open, read, write, etc 
... 

static struct file_operations gpio_fops = {...} // <- look up 

static int __init 
gpio_init(void) 
{ 
    if (!(gpio_sih = si_kattach(SI_OSH))) 
     return -ENODEV; 
    if ((gpio_major = register_chrdev(0, "gpio", &gpio_fops)) < 0) 
     return gpio_major; 
    gpiodev_class = class_create(THIS_MODULE, "gpio"); 
    if (IS_ERR(gpiodev_class)) { 
     printk("Error creating gpio class\n"); 
     return -1; 
    } 
    class_device_create(gpiodev_class, NULL, MKDEV(gpio_major, 0), NULL, "gpio"); 
    return 0; 
} 

static void __exit 
gpio_exit(void) 
{ 
    if (gpiodev_class != NULL) { 
     class_device_destroy(gpiodev_class, MKDEV(gpio_major, 0)); 
     class_destroy(gpiodev_class); 
    } 
    gpiodev_class = NULL; 
    if (gpio_major >= 0) 
     unregister_chrdev(gpio_major, "gpio"); 
    si_detach(gpio_sih); 
} 

module_init(gpio_init); 
module_exit(gpio_exit); 

我需要與另外這款物理設備工作的另一個內核模塊，但它必須在系統中的另一個字符設備與其他文件操作。我該怎麼辦？用類比法寫一個模塊？

//headers 
#include <linux/module.h> 
#include <linux/init.h> 
... 

//declarations 
static si_t *another_gpio_sih; 
static int another_gpio_major; 
static struct class *another_gpiodev_class = NULL; 

//some functions for another_open, another_read, another_write, another_etc 
... 

static struct file_operations another_gpio_fops = {...} // <- look up 

static int __init 
another_gpio_init(void) 
{ 
    if (!(another_gpio_sih = si_kattach(SI_OSH))) 
     return -ENODEV; 
    if ((another_gpio_major = register_chrdev(0, "another_gpio", &another_gpio_fops)) < 0) 
     return gpio_major; 
    another_gpiodev_class = class_create(THIS_MODULE, "another_gpio"); 
    if (IS_ERR(another_gpiodev_class)) { 
     printk("Error creating gpio class\n"); 
     return -1; 
    } 
    class_device_create(another_gpiodev_class, NULL, MKDEV(another_gpio_major, 0), NULL, "another_gpio"); 
    return 0; 
} 

static void __exit 
another_gpio_exit(void) 
{ 
    if (another_gpiodev_class != NULL) { 
     class_device_destroy(another_gpiodev_class, MKDEV(another_gpio_major, 0)); 
     class_destroy(another_gpiodev_class); 
    } 
    another_gpiodev_class = NULL; 
    if (another_gpio_major >= 0) 
     unregister_chrdev(another_gpio_major, "another_gpio"); 
    si_detach(another_gpio_sih); 
} 

module_init(another_gpio_init); 
module_exit(another_gpio_exit); 

或者使用導出全局變量？

EXPORT_SYMBOL(gpio_sih); 
EXPORT_SYMBOL(gpiodev_class); 

和

extern static si_t *another_gpio_sih; 
extern static struct class *another_gpiodev_class; 

感謝。

Answer 1

首先爲什麼需要所有設備？爲什麼不使用標準內核接口： /sys/class/gpio？

它允許從用戶空間讀取，寫入和等待改變gpio。

二。如果你有兩個具有幾乎相同功能的字符設備，爲什麼不在一個驅動程序中處理它們， 將它們設置爲一個主號碼和兩個不同的次要號碼，正確實現從file_operation打開模擬，並且一切正常。