1. 硬件原理圖分析。由原理圖得知LED電路是共陽極的,並分別由2440的GPB5、GPB6、GPB7、GPB8口控制的java
2. 去掉內核已有的LED驅動設置,由於IO口與mini2440開發板的不一致,根本就不能控制板上的LED。node
#gedit arch/arm/plat-s3c24xx/common-smdk.c //註釋掉如下內容linux
/* LED devices */ /* static struct s3c24xx_led_platdata smdk_pdata_led4 = { .gpio = S3C2410_GPF4, .flags = S3C24XX_LEDF_ACTLOW | S3C24XX_LEDF_TRISTATE, .name = "led4", .def_trigger = "timer", }; static struct s3c24xx_led_platdata smdk_pdata_led5 = { .gpio = S3C2410_GPF5, .flags = S3C24XX_LEDF_ACTLOW | S3C24XX_LEDF_TRISTATE, .name = "led5", .def_trigger = "nand-disk", }; static struct s3c24xx_led_platdata smdk_pdata_led6 = { .gpio = S3C2410_GPF6, .flags = S3C24XX_LEDF_ACTLOW | S3C24XX_LEDF_TRISTATE, .name = "led6", }; static struct s3c24xx_led_platdata smdk_pdata_led7 = { .gpio = S3C2410_GPF7, .flags = S3C24XX_LEDF_ACTLOW | S3C24XX_LEDF_TRISTATE, .name = "led7", }; static struct platform_device smdk_led4 = { .name = "s3c24xx_led", .id = 0, .dev = { .platform_data = &smdk_pdata_led4, }, }; static struct platform_device smdk_led5 = { .name = "s3c24xx_led", .id = 1, .dev = { .platform_data = &smdk_pdata_led5, }, }; static struct platform_device smdk_led6 = { .name = "s3c24xx_led", .id = 2, .dev = { .platform_data = &smdk_pdata_led6, }, }; static struct platform_device smdk_led7 = { .name = "s3c24xx_led", .id = 3, .dev = { .platform_data = &smdk_pdata_led7, }, };*/
static struct platform_device __initdata *smdk_devs[] = { &s3c_device_nand, /*&smdk_led4, &smdk_led5, &smdk_led6, &smdk_led7,*/ };
void __init smdk_machine_init(void) { /* Configure the LEDs (even if we have no LED support)*/ /* s3c2410_gpio_cfgpin(S3C2410_GPF4, S3C2410_GPF4_OUTP); s3c2410_gpio_cfgpin(S3C2410_GPF5, S3C2410_GPF5_OUTP); s3c2410_gpio_cfgpin(S3C2410_GPF6, S3C2410_GPF6_OUTP); s3c2410_gpio_cfgpin(S3C2410_GPF7, S3C2410_GPF7_OUTP); s3c2410_gpio_setpin(S3C2410_GPF4, 1); s3c2410_gpio_setpin(S3C2410_GPF5, 1); s3c2410_gpio_setpin(S3C2410_GPF6, 1); s3c2410_gpio_setpin(S3C2410_GPF7, 1);*/ if (machine_is_smdk2443()) smdk_nand_info.twrph0 = 50; s3c_device_nand.dev.platform_data = &smdk_nand_info; platform_add_devices(smdk_devs, ARRAY_SIZE(smdk_devs)); s3c_pm_init(); }
3. 編寫適合mini2440開發板的LED驅動,代碼以下,文件名稱:my2440_leds.c測試
#include <linux/kernel.h> #include <linux/module.h> #include <linux/init.h> #include <linux/fs.h> #include <linux/errno.h> #include <mach/hardware.h> #include <linux/gpio.h> #include <mach/regs-gpio.h> #define DEVICE_NAME "mini2440_leds" //設備名稱 #define LED_MAJOR 260 #define LED_ON 1 //LED亮狀態 #define LED_OFF 0 //LED滅狀態 // 控制LED的IO口 static unsigned long led_table[] = { S3C2410_GPB(5), S3C2410_GPB(6), S3C2410_GPB(7), S3C2410_GPB(8), }; // LED IO口的模式 static unsigned int led_cfg_table[] = { S3C2410_GPIO_OUTPUT, S3C2410_GPIO_OUTPUT, S3C2410_GPIO_OUTPUT, S3C2410_GPIO_OUTPUT, }; static int leds_open(struct inode *inode, struct file *file){ return 0; } static int leds_ioctl(struct inode *inode, struct file *file ,unsigned int cmd, unsigned long arg){ //檢測是第幾個LED,因開發板上只有4個,索引從0開始 if(arg < 0 || arg > 3){ return -EINVAL; } //判斷LED要執行哪一種狀態 switch(cmd){ case LED_ON:{ s3c2410_gpio_setpin(led_table[arg], ~(LED_ON)); break; } case LED_OFF:{ s3c2410_gpio_setpin(led_table[arg], ~(LED_OFF)); break; } default:{ return -EINVAL; } } return 0; } static struct file_operations leds_fops = { .owner = THIS_MODULE, .open = leds_open, .ioctl = leds_ioctl, }; static int __init led_init(void){ int ret, i; for(i = 0; i < 4; i++){ //初始化各IO口爲輸出模式 s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]); //由原理圖可知LED電路是共陽極的(即各IO口輸出低電平0纔會點亮) //這裏初始化爲1,不讓LED點亮 s3c2410_gpio_setpin(led_table[i], ~(LED_OFF)); } // 設備的註冊 ret = register_chrdev(LED_MAJOR, DEVICE_NAME, &leds_fops); if(ret < 0){ printk(DEVICE_NAME " register falid!\n"); } else { printk(DEVICE_NAME " initialized!\n"); } return ret; } static void __exit led_exit(void){ //註銷設備 unregister_chrdev(LED_MAJOR, DEVICE_NAME); } module_init(led_init); module_exit(led_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Benjamin"); MODULE_DESCRIPTION("Mini2440 led driver");
4. 把LED驅動代碼部署到內核中去spa
#cp -f my2440_leds.c /linux-2.6.30.4/drivers/char //把驅動源碼複製到內核驅動的字符設備下調試
#gedit /linux-2.6.30.4/drivers/char/Kconfig //添加LED設備配置
code
config MY2440_LEDS
tristate "My2440 Leds Device"
depends on ARCH_S3C2440
default y
---help---
My2440 User Leds
orm
注:【default y】的意思是將驅動模塊直接編譯到內核索引
#gedit /linux-2.6.30.4/drivers/char/Makefile //添加LED設備配置開發
obj-$(CONFIG_MY2440_LEDS) += my2440_leds.o
5. 配置內核,選擇LED設備選項
#make menuconfig
Device Drivers --->
Character devices --->
<*> My2440 Leds Device (NEW)
6. 編譯內核並下載到開發板上,查看已加載的設備:#cat /proc/devices,能夠看到my2440_leds的主設備號爲231
7. 編寫應用程序測試LED驅動,文件名:leds_test.c
#include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <sys/ioctl.h> int main(int argc, char **argv){ int turn, index, fd; //檢測輸入的參數合法性 if(argc != 3 || sscanf(argv[2], "%d", &index) != 1 || index < 1 || index > 4){ printf("Usage: leds_test on|off 1|2|3|4/n"); exit(1); } if(strcmp(argv[1], "on") == 0){ turn = 1; } else if(strcmp(argv[1], "off") == 0){ turn = 0; } else { printf("Usage: leds_test on|off 1|2|3|4/n"); exit(1); } //打開LED設備 fd = open("/dev/mini2440_leds", 0); if(fd < 0){ printf("Open Led Device Faild!/n"); exit(1); } //IO控制 ioctl(fd, turn, index - 1); //關閉LED設備 close(fd); return 0; }
8. 在開發主機上交叉編譯測試應用程序,並複製到文件系統的/usr/sbin目錄下,而後從新編譯文件系統下載到開發板上
#arm-linux-gcc -o leds_test leds_test.c
9. 在開發板上的文件系統中建立一個LED設備的節點,而後運行測試程序,效果圖以下,觀測開發板上的LED燈,能夠看到每一步的操做對應的LED會點亮或者熄滅
注:本人遇到的問題:
一、因爲linux內核版本的不一樣,my2440_leds.c文件內容稍有不一樣,須要調試。
二、zImage燒到板上以後,啓動系統
cat /proc/devices | grep mini2440_leds
獲得以下結果:
260 mini2440_leds
若是註冊的是混雜設備,即由系統自動分配設備號
查看模塊時,執行
cat /proc/misc | grep mini2440_leds
三、手動建立設備文件
mknod -m 666 /dev/mini2440_leds c 260 0
四、隨內核編譯的狀況,lsmod不能查看到相關模塊