linux 驱动笔记(四)
第六章 GPIO的標準接口函數
1 什么是GPIO的標準接口函數
思考：
1.1設計GPIO驅動的方法？？？
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1.1.1 找到配置/控制GPIO的寄存器，得到了訪問該寄存器的物理地址
1.1.2 申請SFR的物理內存區
1.1.3 IO內存的動態映射，由物理地址得到虛擬地址
1.1.4 通過虛擬地址設置寄存器
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1.2有沒有簡單的方法？？
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應為GPIO 中斷 時鐘....在嵌入式平臺上都是非常常用的模塊。這樣linux內核將這個模塊的控制封裝成的函數，當這些封裝好的函數的時候，大大簡化程序的設計過程。
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2 GPIO標準接口函數的用法
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#include <linux/gpio.h>
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2.1 GPIO的申請與釋放
/* request GPIO, returning 0 or negative errno.
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* non-null labels may be useful for diagnostics.
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*/
int gpio_request(unsigned gpio, const char *label);
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/* release previously-claimed GPIO */
void gpio_free(unsigned gpio);
參數說明：
unsigned gpio ---GPIO號，每個GPIO都有唯一的ID
const char *label ---自定義的GPIO的名字
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2.2 設置GPIO的方向
int gpio_direction_input(unsigned gpio);
int gpio_direction_output(unsigned gpio, int value);
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2.3 設置GPIO的輸出值或者讀取GPIO的輸入值
/* GPIO INPUT: ?return zero or nonzero */
int gpio_get_value(unsigned gpio);
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/* GPIO OUTPUT */
void gpio_set_value(unsigned gpio, int value);
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3 GPIO號
GPIO口號是和處理器是相關的，不同處理器GPIO的數量 名字都是不一樣的。
GPIO號應該是在一個頭文件中定義的。
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linux/arch/arm/mach-s5pv210/include/mach/gpio.h
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/* S5PV210 GPIO number definitions */
#define S5PV210_GPA0(_nr) (S5PV210_GPIO_A0_START + (_nr))
#define S5PV210_GPA1(_nr) (S5PV210_GPIO_A1_START + (_nr))
#define S5PV210_GPB(_nr) (S5PV210_GPIO_B_START + (_nr))
#define S5PV210_GPC0(_nr) (S5PV210_GPIO_C0_START + (_nr))
#define S5PV210_GPC1(_nr) (S5PV210_GPIO_C1_START + (_nr))
#define S5PV210_GPD0(_nr) (S5PV210_GPIO_D0_START + (_nr))
#define S5PV210_GPD1(_nr) (S5PV210_GPIO_D1_START + (_nr))
#define S5PV210_GPE0(_nr) (S5PV210_GPIO_E0_START + (_nr))
#define S5PV210_GPE1(_nr) (S5PV210_GPIO_E1_START + (_nr))
#define S5PV210_GPF0(_nr) (S5PV210_GPIO_F0_START + (_nr))
#define S5PV210_GPF1(_nr) (S5PV210_GPIO_F1_START + (_nr))
#define S5PV210_GPF2(_nr) (S5PV210_GPIO_F2_START + (_nr))
#define S5PV210_GPF3(_nr) (S5PV210_GPIO_F3_START + (_nr))
#define S5PV210_GPG0(_nr) (S5PV210_GPIO_G0_START + (_nr))
#define S5PV210_GPG1(_nr) (S5PV210_GPIO_G1_START + (_nr))
#define S5PV210_GPG2(_nr) (S5PV210_GPIO_G2_START + (_nr))
#define S5PV210_GPG3(_nr) (S5PV210_GPIO_G3_START + (_nr))
#define S5PV210_GPH0(_nr) (S5PV210_GPIO_H0_START + (_nr))
#define S5PV210_GPH1(_nr) (S5PV210_GPIO_H1_START + (_nr))
#define S5PV210_GPH2(_nr) (S5PV210_GPIO_H2_START + (_nr))
#define S5PV210_GPH3(_nr) (S5PV210_GPIO_H3_START + (_nr))
#define S5PV210_GPI(_nr) (S5PV210_GPIO_I_START + (_nr))
#define S5PV210_GPJ0(_nr) (S5PV210_GPIO_J0_START + (_nr))
#define S5PV210_GPJ1(_nr) (S5PV210_GPIO_J1_START + (_nr))
#define S5PV210_GPJ2(_nr) (S5PV210_GPIO_J2_START + (_nr))
#define S5PV210_GPJ3(_nr) (S5PV210_GPIO_J3_START + (_nr))
#define S5PV210_GPJ4(_nr) (S5PV210_GPIO_J4_START + (_nr))
#define S5PV210_MP01(_nr) (S5PV210_GPIO_MP01_START + (_nr))
#define S5PV210_MP02(_nr) (S5PV210_GPIO_MP02_START + (_nr))
#define S5PV210_MP03(_nr) (S5PV210_GPIO_MP03_START + (_nr))
#define S5PV210_MP04(_nr) (S5PV210_GPIO_MP04_START + (_nr))
#define S5PV210_MP05(_nr) (S5PV210_GPIO_MP05_START + (_nr))
#define S5PV210_MP06(_nr) (S5PV210_GPIO_MP06_START + (_nr))
#define S5PV210_MP07(_nr) (S5PV210_GPIO_MP07_START + (_nr))
#define S5PV210_MP10(_nr) (S5PV210_GPIO_MP10_START + (_nr))
#define S5PV210_MP11(_nr) (S5PV210_GPIO_MP11_START + (_nr))
#define S5PV210_MP12(_nr) (S5PV210_GPIO_MP12_START + (_nr))
#define S5PV210_MP13(_nr) (S5PV210_GPIO_MP13_START + (_nr))
#define S5PV210_MP14(_nr) (S5PV210_GPIO_MP14_START + (_nr))
#define S5PV210_MP15(_nr) (S5PV210_GPIO_MP15_START + (_nr))
#define S5PV210_MP16(_nr) (S5PV210_GPIO_MP16_START + (_nr))
#define S5PV210_MP17(_nr) (S5PV210_GPIO_MP17_START + (_nr))
#define S5PV210_MP18(_nr) (S5PV210_GPIO_MP18_START + (_nr))
#define S5PV210_MP20(_nr) (S5PV210_GPIO_MP20_START + (_nr))
#define S5PV210_MP21(_nr) (S5PV210_GPIO_MP21_START + (_nr))
#define S5PV210_MP22(_nr) (S5PV210_GPIO_MP22_START + (_nr))
#define S5PV210_MP23(_nr) (S5PV210_GPIO_MP23_START + (_nr))
#define S5PV210_MP24(_nr) (S5PV210_GPIO_MP24_START + (_nr))
#define S5PV210_MP25(_nr) (S5PV210_GPIO_MP25_START + (_nr))
#define S5PV210_MP26(_nr) (S5PV210_GPIO_MP26_START + (_nr))
#define S5PV210_MP27(_nr) (S5PV210_GPIO_MP27_START + (_nr))
#define S5PV210_MP28(_nr) (S5PV210_GPIO_MP28_START + (_nr))
#define S5PV210_ETC0(_nr) (S5PV210_GPIO_ETC0_START + (_nr))
#define S5PV210_ETC1(_nr) (S5PV210_GPIO_ETC1_START + (_nr))
#define S5PV210_ETC2(_nr) (S5PV210_GPIO_ETC2_START + (_nr))
#define S5PV210_ETC4(_nr) (S5PV210_GPIO_ETC4_START + (_nr))
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例：
LED1 --- GPJ2_0 ?--- S5PV210_GPJ2(0)
LED2 --- GPJ2_1 ?--- S5PV210_GPJ2(1)
LED3 --- GPJ2_2 ?--- S5PV210_GPJ2(2)
LED4 --- GPJ2_3 ?--- S5PV210_GPJ2(3)
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BEEP --- GPD0_0 ?--- S5PV210_GPD0(0)
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4 使用gpio標準接口函數設計驅動的思路
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//char buf[2],buf[1]燈的狀態：1--on，0-->off
// ???????????buf[0]哪一個led：1/2/3/4
ssize_t gec210_led_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
{
int ret;
char kbuf[2];
if(len != 2)
return -EINVAL;
ret = copy_from_user(kbuf,buf,len); //從用戶空間拷貝數據
if(ret!= 0)
return -EFAULT;
if( (kbuf[0]<1) || (kbuf[0]>4) )
return -EINVAL;
gpio_set_value(unsigned gpio, int value);
else
return -EINVAL;
return len;
}
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static struct file_operations gec210_led_fops = {
.owner = THIS_MODULE,
.write = gec210_led_write,
};
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static int __init gec210_led_init(void) //驅動的初始化及安裝函數
{
int gpio_request(unsigned gpio, const char *label);
int gpio_direction_output(unsigned gpio, int value);
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}
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static void __exit gec210_led_exit(void) //驅動卸載函數
{
gpio_free(unsigned gpio);
}
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module_init(gec210_led_init); //驅動的入口
module_exit(gec210_led_exit); //驅動的出口
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A代碼一
1. filename: led_drv.c
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#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/device.h>
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//1)定義一個字符設備cdev
static struct cdev led_drv;
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static unsigned int led_major = 0; //0-->動態分配，>0-->靜態注冊
static unsigned int led_minor = 0;
static dev_t led_drv_num;
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static struct resource * ?gec210_led_res;
static unsigned int *gpj2con_va; //0xe0200280對應的虛擬地址指針
static unsigned int *gpj2dat_va; //0xe0200284對應的虛擬地址指針
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static struct class *gec210_led_class;
static struct device *gec210_led_device;
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?//3)定義文件操作集，并初始化
//char buf[2],buf[1]燈的狀態：1--on，0-->off
// ???????????buf[0]哪一個led：1/2/3/4
ssize_t gec210_led_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
{
int ret;
char kbuf[2];
if(len != 2)
return -EINVAL;
ret = copy_from_user(kbuf,buf,len); //從用戶空間拷貝數據
if(ret!= 0)
return -EFAULT;
if( (kbuf[0]<1) || (kbuf[0]>4) )
return -EINVAL;
if(kbuf[1]==1)
*gpj2dat_va &= ~(1<<(kbuf[0]-1));
else if(kbuf[1]==0)
*gpj2dat_va |= (1<<(kbuf[0]-1));
else
return -EINVAL;
return len;
}
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static struct file_operations gec210_led_fops = {
.owner = THIS_MODULE,
.write = gec210_led_write,
};
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static int __init gec210_led_init(void) //驅動的初始化及安裝函數
{
int ret;
//2)申請/注冊設備號
if(led_major == 0){
ret = alloc_chrdev_region(&led_drv_num, led_minor, 1, "gec210_leds");
}
else{
led_drv_num = MKDEV(led_major,led_minor);
ret = register_chrdev_region(led_drv_num, ?1, "gec210_leds");
}
if(ret < 0){
printk("led_drv_num is error \n");
return ret;
}
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//4)初始化cdev
cdev_init(&led_drv, ?&gec210_led_fops);
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//5)將cdev加入kernel
ret = cdev_add(&led_drv,led_drv_num, 1 );
if(ret < 0){
printk("cdev add error\n");
goto failed_cdev_add;
}
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//6)申請物理內存區，作為一個資源
gec210_led_res = request_mem_region(0xe0200280,8,"GPJ2_LED"); //cat /proc/iomem
if(gec210_led_res == NULL)
{
printk("requst mem region error\n");
ret = -EBUSY;
goto failed_request_mem_region;
}
//7)io內存動態映射
gpj2con_va = ioremap(0xe0200280,8);
if(gpj2con_va == NULL)
{
printk("ioremap error\n");
ret = -EFAULT;
goto failed_ioremap;
}
gpj2dat_va = gpj2con_va + 1; //不是4
printk("gpj2con_va=%p，gpj2dat_va=%p\n", gpj2con_va,gpj2dat_va);
//8)創建class
gec210_led_class = class_create(THIS_MODULE, "led_class");
if(gec210_led_class == NULL)
{
printk("class create error\n");
ret = -EBUSY;
goto failed_class_create;
}
//9)創建device
gec210_led_device = device_create(gec210_led_class,NULL,
??????????????????led_drv_num,NULL,"led_drv"); // /dev/led_drv
if(gec210_led_device == NULL)
{
printk("class device error\n");
ret = -EBUSY;
goto failed_device_create;
}
//led1~4,初始狀態是滅的
*gpj2con_va &= ~0xffff;
*gpj2con_va |= 0x1111;
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*gpj2dat_va |= 0xf;
return 0;
failed_device_create:
class_destroy(gec210_led_class);
failed_class_create:
iounmap(gpj2con_va);
failed_ioremap:
release_mem_region(0xe0200280,8);
failed_request_mem_region:
cdev_del(&led_drv);
failed_cdev_add:
unregister_chrdev_region(led_drv_num, ?1);
return ret;
}
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static void __exit gec210_led_exit(void) //驅動卸載函數
{
unregister_chrdev_region(led_drv_num, ?1);
cdev_del(&led_drv);
release_mem_region(0xe0200280,8);
iounmap(gpj2con_va);
device_destroy(gec210_led_class,led_drv_num);
class_destroy(gec210_led_class);
printk("good bye gec210\n");
}
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module_init(gec210_led_init); //驅動的入口
module_exit(gec210_led_exit); //驅動的出口
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//內核模塊的描述
MODULE_AUTHOR("bobeyfeng@163.com");
MODULE_DESCRIPTION("the first demo of module");
MODULE_LICENSE("GPL"); //符合GPL協議
MODULE_VERSION("V1.0");
//-----------------------------------
2. filename: test.c
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#include <stdio.h>
#include <fcntl.h>
int main(void)
{
int fd;
int ret;
char buf[2];
//"/dev/led_drv" ---linux驅動的設備文件節點（node）
fd = open("/dev/led_drv", O_WRONLY);
if(fd <0)
{
perror("open led_drv:");
return -1;
}
while(1)
{
buf[1] = 1;buf[0]=3; //led3 on
ret = write(fd,buf,sizeof(buf));
if(ret < 0)
{
perror("write led_drv: ");
return -1;
}
sleep(1);
buf[1] = 0;buf[0]=3; //led3 on
ret = write(fd,buf,sizeof(buf));
if(ret < 0)
{
perror("write led_drv: ");
return -1;
}
sleep(1);
}
close(fd);
return 0;
}
//------------------------------------
3. filename: Makefile
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obj-m += led_drv.o
#KERNELDIR := /lib/modules/$(shell uname -r)/build
KERNELDIR := /home/gec/linux-2.6.35.7-gec-v3.0-gt110
PWD:=$(shell pwd)
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default:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
rm -rf *.o *.mod.c *.mod.o *.ko
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//------------------------------------
A代碼二
1. filename: led_drv.c
??/*LED1 --- GPJ2_0 ?--- S5PV210_GPJ2(0)
LED2 --- GPJ2_1 ?--- S5PV210_GPJ2(1)
LED3 --- GPJ2_2 ?--- S5PV210_GPJ2(2)
LED4 --- GPJ2_3 ?--- S5PV210_GPJ2(3)*/
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#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/gpio.h> //GPIO標準接口函數
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//1)定義一個字符設備cdev
static struct cdev led_drv;
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static unsigned int led_major = 0; //0-->動態分配，>0-->靜態注冊
static unsigned int led_minor = 0;
static dev_t led_drv_num;
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static struct class *gec210_led_class;
static struct device *gec210_led_device;
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struct led_gpio{
unsigned int gpio_num;
char gpio_name[12];
};
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static struct led_gpio gec210_leds[4] = {
{
.gpio_num = S5PV210_GPJ2(0),
.gpio_name = "GPJ2_0-LED1",
},
{
.gpio_num = S5PV210_GPJ2(1),
.gpio_name = "GPJ2_1-LED2",
},
{
.gpio_num = S5PV210_GPJ2(2),
.gpio_name = "GPJ2_2-LED2",
},
{
.gpio_num = S5PV210_GPJ2(3),
.gpio_name = "GPJ2_3-LED4",
},
};
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//3)定義文件操作集，并初始化
//char buf[2],buf[1]燈的狀態：1--on，0-->off
// ???????????buf[0]哪一個led：1/2/3/4
ssize_t gec210_led_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
{
int ret;
char kbuf[2];
if(len != 2)
return -EINVAL;
ret = copy_from_user(kbuf,buf,len); //從用戶空間拷貝數據
if(ret!= 0)
return -EFAULT;
if( (kbuf[0]<1) || (kbuf[0]>4) )
return -EINVAL;
if(kbuf[1]==1)
gpio_set_value(gec210_leds[kbuf[0]-1].gpio_num, 0);
else if(kbuf[1]==0)
gpio_set_value(gec210_leds[kbuf[0]-1].gpio_num, 1);
else
return -EINVAL;
return len;
}
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static struct file_operations gec210_led_fops = {
.owner = THIS_MODULE,
.write = gec210_led_write,
};
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static int __init gec210_led_init(void) //驅動的初始化及安裝函數
{
int ret;
int i;
//2)申請/注冊設備號
if(led_major == 0){
ret = alloc_chrdev_region(&led_drv_num, led_minor, 1, "gec210_leds");
}
else{
led_drv_num = MKDEV(led_major,led_minor);
ret = register_chrdev_region(led_drv_num, ?1, "gec210_leds");
}
if(ret < 0){
printk("led_drv_num is error \n");
return ret;
}
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//4)初始化cdev
cdev_init(&led_drv, ?&gec210_led_fops);
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//5)將cdev加入kernel
ret = cdev_add(&led_drv,led_drv_num, 1 );
if(ret < 0){
printk("cdev add error\n");
goto failed_cdev_add;
}
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//6)創建class
gec210_led_class = class_create(THIS_MODULE, "led_class");
if(gec210_led_class == NULL)
{
printk("class create error\n");
ret = -EBUSY;
goto failed_class_create;
}
//7)創建device
gec210_led_device = device_create(gec210_led_class,NULL,
??????????????????led_drv_num,NULL,"led_drv"); // /dev/led_drv
if(gec210_led_device == NULL)
{
printk("class device error\n");
ret = -EBUSY;
goto failed_device_create;
}
for(i=0;i<4;i++)
{
ret = gpio_request(gec210_leds[i].gpio_num, gec210_leds[i].gpio_name);
if(ret < 0)
{
printk("gpio request error %s\n", gec210_leds[i].gpio_name);
goto failed_gpio_request;
}
gpio_direction_output(gec210_leds[i].gpio_num,0x1);
}
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return 0;
failed_gpio_request:
while(i--)//--i
gpio_free(gec210_leds[i].gpio_num);
device_destroy(gec210_led_class,led_drv_num);
failed_device_create:
class_destroy(gec210_led_class);
failed_class_create:
cdev_del(&led_drv);
failed_cdev_add:
unregister_chrdev_region(led_drv_num, ?1);
return ret;
}
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static void __exit gec210_led_exit(void) //驅動卸載函數
{
int i;
unregister_chrdev_region(led_drv_num, ?1);
cdev_del(&led_drv);
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device_destroy(gec210_led_class,led_drv_num);
class_destroy(gec210_led_class);
for(i=0;i<4;i++)
gpio_free(gec210_leds[i].gpio_num);
printk("good bye gec210\n");
}
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module_init(gec210_led_init); //驅動的入口
module_exit(gec210_led_exit); //驅動的出口
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//內核模塊的描述
MODULE_AUTHOR("bobeyfeng@163.com");
MODULE_DESCRIPTION("the first demo of module");
MODULE_LICENSE("GPL"); //符合GPL協議
MODULE_VERSION("V1.0");
//-------------------------------------------------
2. Filename: test.c
#include <stdio.h>
#include <fcntl.h>
int main(void)
{
int fd;
int ret;
char buf[2];
//"/dev/led_drv" ---linux驅動的設備文件節點（node）
fd = open("/dev/led_drv", O_WRONLY);
if(fd <0)
{
perror("open led_drv:");
return -1;
}
while(1)
{
buf[1] = 1;buf[0]=3; //led3 on
ret = write(fd,buf,sizeof(buf));
if(ret < 0)
{
perror("write led_drv: ");
return -1;
}
sleep(1);
buf[1] = 0;buf[0]=3; //led3 on
ret = write(fd,buf,sizeof(buf));
if(ret < 0)
{
perror("write led_drv: ");
return -1;
}
sleep(1);
}
close(fd);
return 0;
}
//--------------------------------------------------
3. Filename: Makefile
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obj-m += led_drv.o
#KERNELDIR := /lib/modules/$(shell uname -r)/build
KERNELDIR := /home/gec/linux-2.6.35.7-gec-v3.0-gt110
PWD:=$(shell pwd)
?
default:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
rm -rf *.o *.mod.c *.mod.o *.ko?
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