🚀 驱动程序
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| #include <linux/init.h> #include <linux/module.h> #include <linux/miscdevice.h> #include <linux/fs.h> #include <linux/io.h> #include <linux/uaccess.h>
#define GPIOE_CFG0 (0x01C20890) #define GPIOE_CFG1 (0x01C20894) #define GPIOE_DATA (0x01C208A0) #define GPIOE_PUL0 (0x01C208AC)
size_t *gpioe_cfg0; size_t *gpioe_cfg1; size_t *gpioe_data; size_t *gpioe_pul0;
static int led_open(struct inode *inode, struct file *file) { *((volatile size_t*)gpioe_cfg0) &= ~(7<<20); *((volatile size_t*)gpioe_cfg0) |= (1<<20); *((volatile size_t*)gpioe_pul0) &= ~(3<<10); *((volatile size_t*)gpioe_pul0) |= (1<<10); *((volatile size_t*)gpioe_data) |= (1 << 5);
printk(KERN_DEBUG"open led!!!\n"); return 0; }
static int led_close(struct inode *inode, struct file *filp) { printk(KERN_DEBUG"close led!!!\n"); return 0; }
static int led_read(struct file *filp, char __user *buff, size_t count, loff_t *offp) { int ret; size_t status = ((*((volatile size_t*)gpioe_data)) >> 5) & 0x01; ret = copy_to_user(buff, &status, 4); if(ret < 0) printk(KERN_DEBUG"read error!!!\n"); else printk(KERN_DEBUG"read led ok!!!\n"); return 0; }
static int led_write(struct file *filp, const char __user *buff, size_t count, loff_t *offp) { int ret; size_t status; ret = copy_from_user(&status, buff, 4); if(ret < 0) printk(KERN_DEBUG"write error!!!\n"); else printk(KERN_DEBUG"write led ok!!!\n");
*((volatile size_t*)gpioe_data) &= ~(1 << 5) ; if(status) { *((volatile size_t*)gpioe_data) |= (1 << 5); } return 0; }
static struct file_operations led_ops = { .owner = THIS_MODULE, .open = led_open, .read = led_read, .write = led_write, .release = led_close, };
struct miscdevice led_dev = { .minor = MISC_DYNAMIC_MINOR, .name = "led_misc", .fops = &led_ops, };
static int misc_init(void) { int ret; ret = misc_register(&led_dev); if (ret < 0) { printk("led_dev register is error!"); return -1; } printk("led_dev register is succeed!\n");
gpioe_cfg0 = ioremap(GPIOE_CFG0, 4); gpioe_cfg1 = ioremap(GPIOE_CFG1, 4); gpioe_data = ioremap(GPIOE_DATA, 4); gpioe_pul0 = ioremap(GPIOE_PUL0, 4);
return 0; }
static void misc_exit(void) { misc_deregister(&led_dev); iounmap(gpioe_cfg0); iounmap(gpioe_cfg1); iounmap(gpioe_data); iounmap(gpioe_pul0); printk("led_dev deregister!\n"); }
module_init(misc_init); module_exit(misc_exit);
MODULE_LICENSE("GPL");
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🚀 应用程序
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| #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <unistd.h> #include <string.h>
int main(int argc, char **argv) { int fd; int val; char *filename = NULL; if(argc !=3) { printf("usage: ./led [device] [on/off]\n"); return -1; }
filename = argv[1]; fd = open(filename, O_RDWR); if (fd < 0) { printf("error, can't open %s\n", filename); return -1; } if(!strcmp(argv[2], "on")) val = 0; else if(!strcmp(argv[2], "off")) val = 1; else { printf("usage: ./led_dev.exe [device] [on/off]\n"); close(fd); return -1; } write(fd, &val, 4); close(fd); return 0; }
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🚀 踩坑记录
1、编译应用程序应用根文件系统的交叉工具链 arm-linux-gcc
, 而不是 arm-linux-gnueabi-gcc
。 下面是操作过程。
编译完根文件系统后,在 buildroot 的主目录,进入 output/host/ 目录,此目录下就是 buildroot 编译根文件系统中安装的交叉工具链。我们可以将该交叉工具链安装到 usr/local 目录下 ,并,比如:
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| cd buildroot-2021.02.4/output/host/ sudo mkdir /usr/local/arm-gcc-app/ sudo cp -a ./* /usr/local/arm-gcc-app/
|
接下来我们添加环境变量,打开/etc/profile 文件,在末尾添加路径:
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| export PATH=$PATH:/usr/local/arm-gcc-app/bin
|
最后重启系统,使环境变量永久生效,就可以使用 arm-linux-gcc
编译C文件了。