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LED驱动

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LED驱动

GPIO模块一般结构：

a. 有多组GPIO，每组有多个GPIO

b. 使能：电源/时钟

c. 模式(Mode)：引脚可用于GPIO或其他功能

d. 方向：引脚Mode设置为GPIO时，可以继续设置它是输出引脚，还是输入引脚

e. 数值：对于输出引脚，可以设置寄存器让它输出高、低电平

​ 对于输入引脚，可以读取寄存器得到引脚的当前电平

LED原理图

image-20211227203745402

image-20211227203833588

LED0对应引脚PI0

相关寄存器

image-20211227203252530

PI0

时钟寄存器

image-20211227205838761

RCC_PLL4CR地址：0x50000000 + 0x894

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* enalbe PLL4, it is clock source for all gpio */
	*RCC_PLL4CR |= (1<<0);
	while ((*RCC_PLL4CR & (1<<1)) == 0);

使能GPIOI

image-20211227210036696

RCC_MP_AHB4ENSETR地址：0x50000000 + 0xA28

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/* enable gpioI */
	*RCC_MP_AHB4ENSETR |= (1<<8);

PI0模式设置

image-20211227210347472

GPIOI_MODER地址：0x5000A000 + 0x00

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/*
	 * configure gpI0 as gpio
	 * configure gpio as output 
	 */
	*GPIOI_MODER &= ~(3<<0);
	*GPIOI_MODER |= (1<<0);

输出高低电平

image-20211227210634694

GPIOI_BSRR地址： 0x5000A000 + 0x18

驱动程序

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#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/mutex.h>
#include <linux/wait.h>
#include <linux/uaccess.h>
#include <asm/io.h>
#include <linux/device.h>

static int major;
static struct class *led_class;

/* registers */
// RCC_PLL4CR地址：0x50000000 + 0x894
static volatile unsigned int *RCC_PLL4CR;

// RCC_MP_AHB4ENSETR 地址：0x50000000 + 0xA28
static volatile unsigned int *RCC_MP_AHB4ENSETR;

// GPIOI_MODER 地址：0x5000A000 + 0x00
static volatile unsigned int *GPIOI_MODER;

// GPIOI_BSRR 地址： 0x5000A000 + 0x18
static volatile unsigned int *GPIOI_BSRR;

static ssize_t led_write(struct file *filp, const char __user *buf,
			 size_t count, loff_t *ppos)
{
	char val;
	/* copy_from_user : get data from app */
	copy_from_user(&val, buf, 1);

	/* to set gpio register: out 1/0 */
	if (val)
	{
		/* set gpa10 to let led on */
		*GPIOI_BSRR = (1<<16);
	}
	else
	{

		/* set gpa10 to let led off */
		*GPIOI_BSRR = (1<<0);
	}
	return 1;
}

static int led_open(struct inode *inode, struct file *filp)
{
	/* enalbe PLL4, it is clock source for all gpio */
	*RCC_PLL4CR |= (1<<0);
	while ((*RCC_PLL4CR & (1<<1)) == 0);
	
	/* enable gpioI */
	*RCC_MP_AHB4ENSETR |= (1<<8);
	
	/*
	 * configure gpI0 as gpio
	 * configure gpio as output 
	 */
	*GPIOI_MODER &= ~(3<<0);
	*GPIOI_MODER |= (1<<0);

	return 0;
}

static struct file_operations led_fops = {
	.owner		= THIS_MODULE,
	.write		= led_write,
	.open		= led_open,
};

/* 入口函数 */
static int __init led_init(void)
{
	printk("%s %s %d\n", __FILE__, __FUNCTION__, __LINE__);
	
	major = register_chrdev(0, "100ask_led", &led_fops);

	/* ioremap(base_phy, size); */
	// RCC_PLL4CR地址：0x50000000 + 0x894
	RCC_PLL4CR = ioremap(0x50000000 + 0x894, 4);
	
	// RCC_MP_AHB4ENSETR 地址：0x50000000 + 0xA28
	RCC_MP_AHB4ENSETR = ioremap(0x50000000 + 0xA28, 4);
	
	// GPIOI_MODER 地址：0x5000A000 + 0x00
	GPIOI_MODER = ioremap(0x5000A000 + 0x00, 4);
	
	// GPIOI_BSRR 地址： 0x5000A000 + 0x18
	GPIOI_BSRR = ioremap(0x5000A000 + 0x18, 4);

	led_class = class_create(THIS_MODULE, "myled");
	device_create(led_class, NULL, MKDEV(major, 0), NULL, "myled"); /* /dev/myled */
	
	return 0;
}

static void __exit led_exit(void)
{
	iounmap(RCC_PLL4CR);
	iounmap(RCC_MP_AHB4ENSETR);
	iounmap(GPIOI_MODER);
	iounmap(GPIOI_BSRR);
	
	device_destroy(led_class, MKDEV(major, 0));
	class_destroy(led_class);
	
	unregister_chrdev(major, "100ask_led");
}

module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");

测试程序

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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>


// ledtest /dev/myled on
// ledtest /dev/myled off

int main(int argc, char **argv)
{
	int fd;
	char status = 0;
	
	if (argc != 3)
	{
		printf("Usage: %s <dev> <on|off>\n", argv[0]);
		printf("  eg: %s /dev/myled on\n", argv[0]);
		printf("  eg: %s /dev/myled off\n", argv[0]);
		return -1;
	}
	// open
	fd = open(argv[1], O_RDWR);
	if (fd < 0)
	{
		printf("can not open %s\n", argv[0]);
		return -1;
	}

	// write
	if (strcmp(argv[2], "on") == 0)
	{
		status = 1;
	}

	write(fd, &status, 1);
	return 0;	
}

实验

Makefile文件

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# 1. 使用不同的开发板内核时, 一定要修改KERN_DIR
# 2. KERN_DIR中的内核要事先配置、编译, 为了能编译内核, 要先设置下列环境变量:
# 2.1 ARCH,          比如: export ARCH=arm64
# 2.2 CROSS_COMPILE, 比如: export CROSS_COMPILE=aarch64-linux-gnu-
# 2.3 PATH,          比如: export PATH=$PATH:/home/book/100ask_roc-rk3399-pc/ToolChain-6.3.1/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin 
# 注意: 不同的开发板不同的编译器上述3个环境变量不一定相同,
#       请参考各开发板的高级用户使用手册

KERN_DIR = /home/book/100ask_stm32mp157_pro-sdk/Linux-5.4

all:
	make -C $(KERN_DIR) M=`pwd` modules 
	$(CROSS_COMPILE)gcc -o ledtest ledtest.c 

clean:
	make -C $(KERN_DIR) M=`pwd` modules clean
	rm -rf modules.order
	rm -f ledtest

obj-m	+= led_drv.o

ubuntn

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book@100ask:~/01_all_series_quickstart/05_嵌入式Linux驱动开发基础知识/source/02_led_drv/00_led_drv_simple/stm32mp157$ make
make -C /home/book/100ask_stm32mp157_pro-sdk/Linux-5.4 M=`pwd` modules
make[1]: Entering directory '/home/book/100ask_stm32mp157_pro-sdk/Linux-5.4'
  CC [M]  /home/book/01_all_series_quickstart/05_嵌入式Linux驱动开发基础知识/source/02_led_drv/00_led_drv_simple/stm32mp157/led_drv.o
  Building modules, stage 2.
  MODPOST 1 modules
  LD [M]  /home/book/01_all_series_quickstart/05_嵌入式Linux驱动开发基础知识/source/02_led_drv/00_led_drv_simple/stm32mp157/led_drv.ko
make[1]: Leaving directory '/home/book/100ask_stm32mp157_pro-sdk/Linux-5.4'
arm-buildroot-linux-gnueabihf-gcc -o ledtest ledtest.c
book@100ask:~/01_all_series_quickstart/05_嵌入式Linux驱动开发基础知识/source/02_led_drv/00_led_drv_simple/stm32mp157$ cp led_drv.ko ledtest /home/book/nfs_rootfs/

开发板

挂载NFS

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busybox  mount -t nfs -o nolock,vers=3 192.168.5.11:/home/book/nfs_rootfs /mnt

关闭心跳灯

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echo none > /sys/class/leds/sys-led/trigger

挂载驱动

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root@ATK-stm32mp1:/mnt# insmod led_drv.ko
[ 2844.864125] /home/book/01_all_series_quickstart/05_嵌入式Linux驱动开发基础知识/source/02_led_drv/00_led_drv_simple/stm32mp157/led_drv.c led_init 81
root@ATK-stm32mp1:/mnt# /mnt/ledtest /dev/myled on    #开灯
root@ATK-stm32mp1:/mnt# /mnt/ledtest /dev/myled off   #关灯