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08 - debugfs

时间：2024-08-30 18:51:40浏览次数：14  
标签：struct rtc debugfs 08 static root hello

---- 整理自 王利涛老师 课程
实验环境：宅学部落 www.zhaixue.cc

文章目录

0. 什么是 debugfs

  • 天生为调试内核而开发，一个基于内存的文件系统，它是基于 libfs，主要调试功能
  • 相比 procfs、sysfs 的优势
    • procfs：调试内核、修改寄存器，进程的信息导出到用户空间
      proc：需要实现它对应的底层的 read、write 接口，需要添加很多的调试代码
    • sysfs：设备模型导出到用户空间
    • debugfs：简化了导出的接口，一行代码，就可以将内核变量、数组、链表、内存中数据、寄存器导出导出到用户空间，方便调试

1. debugfs 配置编译和注册运行

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2. 第一个 debugfs 编程示例

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/debugfs.h>

static unsigned int hello_value;
static struct dentry *hello_root;

static int __init hello_debugfs_init(void)
{
    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create debugfs dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    debugfs_create_u32("hello_reg", 0644, hello_root, &hello_value);

    return 0;
}

static void __exit hello_debugfs_exit(void)
{
    if (hello_root) {
        debugfs_remove_recursive(hello_root);
    }
    //debugfs_remove();
}

module_init(hello_debugfs_init);
module_exit(hello_debugfs_exit);
MODULE_LICENSE("GPL");


ifneq ($(KERNELRELEASE),)
obj-m := hello.o
else
EXTRA_CFLAGS += -DDEBUG 
KDIR:=/home/code_folder/uboot_linux_rootfs/kernel/linux-5.10.4
ARCH_ARGS := ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-
all:
	make $(ARCH_ARGS) -C $(KDIR) M=$(PWD) modules
clean:
	make $(ARCH_ARGS) -C $(KDIR) M=$(PWD) modules clean
endif

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3. 通过 debugfs 导出整型数据

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/debugfs.h>

static unsigned int hello_value;
static struct dentry *hello_root;

static u8 u8_a;
static u16 u16_a;
static u64 u64_a;
static size_t size_t_a;
static unsigned long ulong_a;
static bool bool_a;


static int __init hello_debugfs_init(void)
{
    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create debugfs dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    debugfs_create_u32("hello_reg", 0644, hello_root, &hello_value);
    debugfs_create_u8("u8_reg", 0644, hello_root, &u8_a);
    debugfs_create_u16("u16_reg", 0644, hello_root, &u16_a);
    debugfs_create_u64("u64_reg", 0644, hello_root, &u64_a);
    debugfs_create_size_t("size_t_reg", 0644, hello_root, &size_t_a);
    debugfs_create_ulong("ulong_reg", 0644, hello_root, &ulong_a);
    debugfs_create_bool("bool_reg", 0644, hello_root, &bool_a);

    return 0;
}

static void __exit hello_debugfs_exit(void)
{
    if (hello_root)
        debugfs_remove_recursive(hello_root);
}

module_init(hello_debugfs_init);
module_exit(hello_debugfs_exit);
MODULE_LICENSE("GPL");


ifneq ($(KERNELRELEASE),)
obj-m := hello.o
else
EXTRA_CFLAGS += -DDEBUG 
KDIR:=/home/code_folder/uboot_linux_rootfs/kernel/linux-5.10.4
ARCH_ARGS := ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-
all:
	make $(ARCH_ARGS) -C $(KDIR) M=$(PWD) modules
clean:
	make $(ARCH_ARGS) -C $(KDIR) M=$(PWD) modules clean
endif

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4. 通过 debugfs 导出 16 进制数据

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/debugfs.h>

static unsigned int hello_value;
static struct dentry *hello_root;

static u8 u8_a;
static u16 u16_a;
static u64 u64_a;

static int __init hello_debugfs_init(void)
{
    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create debugfs dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    debugfs_create_x32("hello_reg", 0644, hello_root, &hello_value);
    debugfs_create_x8("u8_reg", 0644, hello_root, &u8_a);
    debugfs_create_x16("u16_reg", 0644, hello_root, &u16_a);
    debugfs_create_x64("u64_reg", 0644, hello_root, &u64_a);

    return 0;
}

static void __exit hello_debugfs_exit(void)
{
    if (hello_root) {
        debugfs_remove_recursive(hello_root);
    }
}

module_init(hello_debugfs_init);
module_exit(hello_debugfs_exit);
MODULE_LICENSE("GPL");


ifneq ($(KERNELRELEASE),)
obj-m := hello.o
else
EXTRA_CFLAGS += -DDEBUG 
KDIR:=/home/code_folder/uboot_linux_rootfs/kernel/linux-5.10.4
ARCH_ARGS := ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-
all:
	make $(ARCH_ARGS) -C $(KDIR) M=$(PWD) modules
clean:
	make $(ARCH_ARGS) -C $(KDIR) M=$(PWD) modules clean
endif

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5. 通过 debugfs 导出数组

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/debugfs.h>

static struct dentry *hello_root;
static u32 hello_array[8] = {1,2,3,4,5,6,7,8};

static struct debugfs_u32_array array_info = {
    .array = hello_array,
    .n_elements = 8,
};

static int __init hello_debugfs_init(void)
{
    int ret = 0;

    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create debugfs dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    debugfs_create_u32_array("hello_array", S_IWUGO, hello_root, &array_info);

    return ret;
}

static void __exit hello_debugfs_exit(void)
{
    if (hello_root) {
        debugfs_remove_recursive(hello_root);
    }
}

module_init(hello_debugfs_init);
module_exit(hello_debugfs_exit);
MODULE_LICENSE("GPL");

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6. 通过 debugfs 导出内存数据块

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/slab.h>

static struct dentry *hello_root;
static u32 hello_array[8] ={ 65, 66, 67, 68, 69, 70, 70, 71 };
static char *mem_block_p = NULL;

static struct debugfs_u32_array array_info = {
    .array = hello_array,
    .n_elements = 8,
};

static struct debugfs_blob_wrapper hello_blob = {
    .data = hello_array,
    .size = 8 * sizeof(u32),
};

static struct debugfs_blob_wrapper hello_mem;


static int __init hello_debugfs_init(void)
{
    int ret = 0;

    mem_block_p = kmalloc(32, GFP_ATOMIC);
    if (!mem_block_p) {
        pr_err("%s: kmalloc memory failed\n", __func__);
        return -ENOMEM;
    }
    memcpy(mem_block_p, "hello zhaixue.cc\n", 20);
    hello_mem.data = mem_block_p;
    hello_mem.size = 32;

    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create debugfs dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    debugfs_create_u32_array("hello_array", S_IWUGO, hello_root, &array_info);
    debugfs_create_blob("hello_blob", S_IWUGO, hello_root, &hello_blob);
    debugfs_create_blob("hello_mem", S_IWUGO, hello_root, &hello_mem);

    return ret;
}

static void __exit hello_debugfs_exit(void)
{
    if (hello_root) {
        debugfs_remove_recursive(hello_root);
    }

    kfree(mem_block_p);
}

module_init(hello_debugfs_init);
module_exit(hello_debugfs_exit);
MODULE_LICENSE("GPL");

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7. 通过 debugfs 导出自定义格式数据

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/debugfs.h>

static struct dentry *hello_root;

static unsigned int hello_value;
static char hello_buf[100];


static ssize_t hello_read(struct file *filp, char __user *buf, size_t count,
                            loff_t *ppos)
{
    int ret;

    if (*ppos >= 100)
        return 0;
    if (*ppos + count > 100)
        count = 100 - *ppos;

    ret = copy_to_user(buf, hello_buf, count);
    if (ret) {
        return -EFAULT;
    }
    *ppos += count;

    return count;
}

static ssize_t hello_write(struct file *filp, const char __user *buf, size_t count,
                            loff_t *ppos)
{
    int ret;
    
    if (*ppos > 100)
        return 0;
    if (*ppos + count > 100)
        count = 100 - *ppos;
    
    ret = copy_from_user(hello_buf, buf, count);
    if (ret)
        return -EFAULT;
    *ppos += count;

    return count;
}

static struct file_operations hello_fops = {
    .owner = THIS_MODULE,
    .read = hello_read,
    .write = hello_write,
};

static int __init hello_debugfs_init(void)
{
    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create debugfs dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    debugfs_create_x32("hello_reg", 0644, hello_root, &hello_value);
    debugfs_create_file("hello_buffer", S_IWUGO, hello_root, NULL, &hello_fops);

    return 0;
}

static void __exit hello_debugfs_exit(void)
{
    if (hello_root) {
        debugfs_remove_recursive(hello_root);
    }
}

module_init(hello_debugfs_init);
module_exit(hello_debugfs_exit);
MODULE_LICENSE("GPL");

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8. 在 debugfs 下使用 seq_file 接口

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>

static struct dentry *hello_root;

static char hello_buf[100];


static int hello_debugfs_show(struct seq_file *s, void *data)
{
    char* p = s->private;
    seq_printf(s, "%s", p);
    return 0;
}

static int hello_open(struct inode* inode, struct file* file)
{
    return single_open(file, hello_debugfs_show, inode->i_private);
}

static ssize_t hello_write(struct file *filp, const char __user *buf, size_t count,
                            loff_t *ppos)
{
    int ret;
    
    if (*ppos > 100)
        return 0;
    if (*ppos + count > 100)
        count = 100 - *ppos;
    
    ret = copy_from_user(hello_buf, buf, count);
    if (ret)
        return -EFAULT;
    *ppos += count;

    return count;
}

static struct file_operations hello_fops = {
    .owner = THIS_MODULE,
    .open = hello_open,
    .read = seq_read,
    .write = hello_write,
    .llseek = seq_lseek,
    .release = single_release,
};

static int __init hello_debugfs_init(void)
{
    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create debugfs dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    debugfs_create_file("hello_buffer", S_IWUGO, hello_root, hello_buf, &hello_fops);

    return 0;
}

static void __exit hello_debugfs_exit(void)
{
    if (hello_root) {
        debugfs_remove_recursive(hello_root);
    }
}

module_init(hello_debugfs_init);
module_exit(hello_debugfs_exit);
MODULE_LICENSE("GPL");

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9. 使用 seq_file 接口访问数组

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>

struct hello_struct {
    unsigned int value;
    unsigned int id;
};

static struct dentry *hello_root;
static struct hello_struct hello_array[8];
static char hello_buf[64];
static int index = 0;


static void *hello_seq_start(struct seq_file *s, loff_t *pos)
{
    printk("------start: *pos = %lld\n", *pos);
    if (*pos == 0) {
        return &hello_array[0];
    } else {
        *pos = 0;
        return NULL;
    }
}

static void *hello_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
    struct hello_struct *p_node = NULL;
    (*pos)++;
    printk("------next: *pos = %lld\n", *pos);
    p_node = &hello_array[*pos];
    
    if (*pos == 8) {
        return NULL;
    }
    return p_node;
}

static void hello_seq_stop(struct seq_file *s, void *v)
{
    printk("stop\n");
}

static int hello_seq_show(struct seq_file *s, void *v)
{
    struct hello_struct *p = (struct hello_struct *)v;
    printk("------show: id = %d\n", p->id);
    if (p->id > 0) {
        seq_printf(s, "hello_arr[%d].value = 0x%x\n", p->id-1, \
                      hello_array[p->id-1].value);
    }

    return 0;
}

static struct seq_operations hello_seq_ops = {
    .start = hello_seq_start,
    .next  = hello_seq_next,
    .stop  = hello_seq_stop,
    .show  = hello_seq_show,
};

static int hello_open(struct inode* inode, struct file* file)
{
    return seq_open(file, &hello_seq_ops);
}

static ssize_t hello_write(struct file *filp, const char __user *buf, size_t len,
                            loff_t *ppos)
{
    int ret;
    
    if (len == 0 || len > 64) {
        ret = -EFAULT;
        return ret;
    }

    ret = copy_from_user(hello_buf, buf, len);
    if (ret) {
        return -EFAULT;
    }

    printk("hello_write: index = %d\n", index);
    hello_array[index].id = index + 1;
    hello_array[index].value = simple_strtoul(hello_buf, NULL, 0);
    index++;
    if (index == 8) {
        index = 0;
    }

    return len;
}

static struct file_operations hello_fops = {
    .owner = THIS_MODULE,
    .open = hello_open,
    .read = seq_read,
    .write = hello_write,
    .llseek = seq_lseek,
};

static int __init hello_debugfs_init(void)
{
    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create debugfs dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    debugfs_create_file("hello_buffer", S_IWUGO, hello_root, hello_array, &hello_fops);

    return 0;
}

static void __exit hello_debugfs_exit(void)
{
    if (hello_root) {
        debugfs_remove_recursive(hello_root);
    }
}

module_init(hello_debugfs_init);
module_exit(hello_debugfs_exit);
MODULE_LICENSE("GPL");

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10. 使用 seq_file 接口访问链表

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

static struct dentry *hello_root;

static char hello_buf[64];
static struct list_head hello_list_head;

struct hello_struct {
    unsigned int value;
    struct list_head node;
};


static void *hello_seq_start(struct seq_file *s, loff_t *pos)
{
   return seq_list_start(&hello_list_head, *pos);
}

static void *hello_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
    return seq_list_next(v, &hello_list_head, pos);
}

static void hello_seq_stop(struct seq_file *s, void *v)
{
    // printk("stop\n");
}

static int hello_seq_show(struct seq_file *s, void *v)
{
    struct hello_struct *p_node = list_entry(v, struct hello_struct, node);
    seq_printf(s, "node = 0x%x\n", p_node->value);

    return 0;
}

static struct seq_operations hello_seq_ops = {
    .start = hello_seq_start,
    .next  = hello_seq_next,
    .stop  = hello_seq_stop,
    .show  = hello_seq_show,
};

static int hello_open(struct inode* inode, struct file* file)
{
    return seq_open(file, &hello_seq_ops);
}

static ssize_t hello_write(struct file *filp, const char __user *buf, size_t len,
                            loff_t *ppos)
{
    int ret;
    struct hello_struct *data;

    if (len == 0 || len > 64) {
        ret = -EFAULT;
        return ret;
    }

    ret = copy_from_user(hello_buf, buf, len);
    if (ret) {
        return -EFAULT;
    }

    data = kmalloc(sizeof(struct hello_struct), GFP_KERNEL);
    if (data != NULL) {
        data->value = simple_strtoul(hello_buf, NULL, 0);
        list_add(&data->node, &hello_list_head);
    }

    return len;
}

static struct file_operations hello_fops = {
    .open = hello_open,
    .read = seq_read,
    .write = hello_write,
    .llseek = seq_lseek,
};

static int __init hello_debugfs_init(void)
{
    int ret = 0;

    INIT_LIST_HEAD(&hello_list_head);

    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create debugfs dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    debugfs_create_file("hello_list", S_IWUGO, hello_root, NULL, &hello_fops);

    return 0;
}

static void __exit hello_debugfs_exit(void)
{
    struct hello_struct *data;

    if (hello_root) {
        debugfs_remove_recursive(hello_root);
    }

    while (!list_empty(&hello_list_head)) {
        data = list_entry(hello_list_head.next, struct hello_struct, node);
        list_del(&data->node);
        kfree(data);
    }
}

module_init(hello_debugfs_init);
module_exit(hello_debugfs_exit);
MODULE_LICENSE("GPL");

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11. 通过 debugfs 导出寄存器列表

#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/cdev.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/debugfs.h>

typedef volatile struct {
    unsigned long  RTCDR;    /* +0x00: data register */
    unsigned long  RTCMR;    /* +0x04: match register */
    unsigned long  RTCLR;    /* +0x08: load register */
    unsigned long  RTCCR;    /* +0x0C: control register */
    unsigned long  RTCIMSC;  /* +0x10: interrupt mask set and clear register*/
    unsigned long  RTCRIS;   /* +0x14: raw interrupt status register*/
    unsigned long  RTCMIS;   /* +0x18: masked interrupt status register */
    unsigned long  RTCICR;   /* +0x1C: interrupt clear register */
} rtc_reg_t;

struct rtc_time {
    unsigned int year;
    unsigned int mon;
    unsigned int day;
    unsigned int hour;
    unsigned int min;
    unsigned int sec;
};

#define RTC_BASE 0x10017000

static volatile rtc_reg_t *regs = NULL;
static unsigned long cur_time = 0;
static struct rtc_time tm;

static dev_t devno;
static struct cdev *rtc_cdev;

static void rtc_time_translate(void)
{
    tm.hour = (cur_time  % 86400) / 3600;
    tm.min  = (cur_time  % 3600) / 60;
    tm.sec  = cur_time  % 60;
}

static void set_rtc_alarm(void)
{
    unsigned long tmp = 0;
    
    tmp = regs->RTCCR;
    tmp = tmp & 0xFFFFFFFE;
    regs->RTCCR = tmp;

    cur_time = regs->RTCDR;
    regs->RTCMR = cur_time + 15;

    regs->RTCICR = 0x1;
    regs->RTCIMSC = 0x1;

    tmp = regs->RTCCR;
    tmp = tmp | 0x1;
    regs->RTCCR = tmp;
}

static irqreturn_t rtc_alarm_handler(int irq, void *dev_id)
{
    cur_time = regs->RTCDR;
    rtc_time_translate();
    printk("\nalarm: beep~ beep~ \n");
    printk("\n    %d:%d:%d\n", tm.hour, tm.min, tm.sec);
    regs->RTCICR = 1;
    set_rtc_alarm();
    return IRQ_HANDLED;
}

static struct file_operations rtc_fops;

static const struct debugfs_reg32 rtc_reg_array[] = {
    {
        .name   = "RTCDR",
        .offset = 0x0
    },
    {
        .name   = "RTCMR",
        .offset = 0x4
    },
    {
        .name   = "RTCLR",
        .offset = 0x8
    },
    {
        .name   = "RTCCR",
        .offset = 0xC
    },
    {
        .name   = "RTCIMSC",
        .offset = 0x10
    },
    {
        .name   = "RTCRIS",
        .offset = 0x14
    },
    {
        .name   = "RTCMIS",
        .offset = 0x18
    },
    {
        .name   = "RTCICR",
        .offset = 0x1C
    }
};

static struct debugfs_regset32 rtc_regset; // <------
static struct dentry *hello_root;

static int __init rtc_init(void)
{
    int ret = 0;
    
    regs = (rtc_reg_t *)ioremap(RTC_BASE, sizeof(rtc_reg_t));

    ret = alloc_chrdev_region(&devno, 0, 1, "rtc-demo");
    if (ret) {
        printk("alloc char device number failed!\n");
        return ret;
    }
    printk("RTC devnum:%d minornum:%d\n", MAJOR(devno), MINOR(devno));

    rtc_cdev = cdev_alloc();
    cdev_init(rtc_cdev, &rtc_fops);

    ret = cdev_add(rtc_cdev, devno, 1);
    if (ret < 0) {
        printk("cdev_add failed..\n");
        return -1;
    } else {
        printk("Register char module: rtc success!\n");
    }

    ret = request_irq(39, rtc_alarm_handler, 0, "rtc-test", NULL);
    if (ret == -1) {
        printk("request_irq failed!\n");
        return -1;
    }

    set_rtc_alarm();

    hello_root = debugfs_create_dir("hello", NULL);
    if (IS_ERR(hello_root)) {
        pr_err("%s: create rtc dir failed\n", __func__);
        return PTR_ERR(hello_root);
    }

    rtc_regset.regs  = rtc_reg_array;
    rtc_regset.nregs = 8;
    rtc_regset.base  = (void *)regs;
    debugfs_create_regset32("reglist", 0644, hello_root, &rtc_regset); // <------

    return 0;
}

static void __exit rtc_exit(void)
{
    if (hello_root) {
        debugfs_remove_recursive(hello_root);
    }

    free_irq(39, NULL);
    cdev_del(rtc_cdev);
    unregister_chrdev_region(devno, 1);
}

module_init(rtc_init);
module_exit(rtc_exit);
MODULE_LICENSE("GPL");

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12. 通过 debugfs 修改 RTC 寄存器

  • 关闭内核自带的 rtc 驱动
  • 打开 debugfs 选项

在这里插入图片描述
在这里插入图片描述

#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/cdev.h>
#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>

typedef volatile struct {
    unsigned int  RTCDR;    /* +0x00: data register */
    unsigned int  RTCMR;    /* +0x04: match register */
    unsigned int  RTCLR;    /* +0x08: load register */
    unsigned int  RTCCR;    /* +0x0C: control register */
    unsigned int  RTCIMSC;  /* +0x10: interrupt mask set and clear register*/
    unsigned int  RTCRIS;   /* +0x14: raw interrupt status register*/
    unsigned int  RTCMIS;   /* +0x18: masked interrupt status register */
    unsigned int  RTCICR;   /* +0x1C: interrupt clear register */
}rtc_reg_t;

struct rtc_time {
    unsigned int year;
    unsigned int mon;
    unsigned int day;
    unsigned int hour;
    unsigned int min;
    unsigned int sec;
};

#define RTC_BASE 0x10017000

static volatile rtc_reg_t *regs = NULL;
static unsigned long cur_time = 0;
static struct rtc_time tm;

static void rtc_time_translate(void)
{
    tm.hour = (cur_time  % 86400) / 3600;
    tm.min  = (cur_time  % 3600) / 60;
    tm.sec  = cur_time  % 60;
}

static void rtc_tm_to_time(void)
{
    cur_time = tm.hour * 3600 + tm.min * 60 + tm.sec;
}


static dev_t devno;
static struct cdev *rtc_cdev;

static int rtc_open(struct inode *inode, struct file *fp)
{
    return 0;
}

static int rtc_release(struct inode *inode, struct file *fp)
{
    return 0;
}

static ssize_t rtc_read(struct file *fp, char __user *buf, 
                           size_t size, loff_t *pos)
{
    cur_time = regs->RTCDR;
    rtc_time_translate();
    if (copy_to_user(buf, &tm, sizeof(struct rtc_time)) != 0){
        printk("rtc_read error!\n");
        return -1;
    }

    return sizeof(struct rtc_time);
}

static ssize_t rtc_write(struct file *fp, const char __user *buf, 
                            size_t size, loff_t *pos)
{
    int len = 0;
    
    len = sizeof(struct rtc_time);
    if (copy_from_user(&tm, buf, len) != 0) {
        printk("rtc_write error!\n");
        return -1;
    }
    rtc_tm_to_time();
    regs->RTCLR = cur_time;

    return len;
}

/* standard file I/O system call interface */
static const struct file_operations rtc_fops = {
    .owner   = THIS_MODULE,
    .read    = rtc_read,
    .write   = rtc_write,
    .open    = rtc_open,
    .release = rtc_release,
};

static void set_rtc_alarm(void)
{
    unsigned int tmp = 0;
    
    tmp = regs->RTCCR;
    tmp = tmp & 0xFFFFFFFE;
    regs->RTCCR = tmp;

    cur_time = regs->RTCDR;
    regs->RTCMR = cur_time + 25; // <------

    regs->RTCICR = 1;
    regs->RTCIMSC = 1; // <------

    tmp = regs->RTCCR;
    tmp = tmp | 0x1;
    regs->RTCCR = tmp;
}

static irqreturn_t rtc_alarm_handler(int irq, void *dev_id)
{
    cur_time = regs->RTCDR;
    rtc_time_translate();
    printk("\nalarm: beep~ beep~ \n");
    printk("\n    %d:%d:%d\n", tm.hour, tm.min, tm.sec);
    regs->RTCICR = 1;
    set_rtc_alarm();
    return IRQ_HANDLED;
}


static struct dentry *rtc_root;
static struct dentry *reg_dir;
static u32 *reg_p = NULL;

static int __init rtc_init(void)
{
    int ret = 0;
    
    regs = (rtc_reg_t *)ioremap(RTC_BASE, sizeof(rtc_reg_t));
    printk("rtc_init\n");

    ret = alloc_chrdev_region(&devno, 0, 1, "rtc-demo");
    if (ret) {
        printk("alloc char device number failed!\n");
        return ret;
    }
    printk("RTC devnum:%d minornum:%d\n", MAJOR(devno), MINOR(devno));

    rtc_cdev = cdev_alloc();
    cdev_init(rtc_cdev, &rtc_fops);

    ret = cdev_add(rtc_cdev, devno, 1);
    if (ret < 0) {
        printk("cdev_add failed..\n");
        return -ret;
    } else {
        printk("Register char module: rtc success!\n");
    }
    
    ret = request_irq(39, rtc_alarm_handler, 0, "rtc-test", NULL);
    if (ret == -1) {
        printk("request_irq failed!\n");
        return -ret;
    }

    rtc_root = debugfs_create_dir("rtc", NULL);
    if (IS_ERR(rtc_root)) {
        pr_err("%s: create rtc dir failed\n", __func__);
        return PTR_ERR(rtc_root);
    }
    reg_dir = debugfs_create_dir("reg_list", rtc_root);
    if (IS_ERR(reg_dir)) {
        pr_err("%s: create reg dir failed\n", __func__);
        return PTR_ERR(reg_dir);
    }

    reg_p = (u32 *)regs;
    debugfs_create_x32("RTCDR", 0644, reg_dir, reg_p);
    debugfs_create_x32("RTCMR", 0644, reg_dir, reg_p + 0x01);
    debugfs_create_x32("RTCLR", 0644, reg_dir, reg_p + 0x02);
    debugfs_create_x32("RTCCR", 0644, reg_dir, reg_p + 0x03);
    debugfs_create_x32("RTCIMSC", 0644, reg_dir, reg_p + 0x04);
    debugfs_create_x32("RTCRIS", 0644, reg_dir, reg_p + 0x05);
    debugfs_create_x32("RTCMIS", 0644, reg_dir, reg_p + 0x06);
    debugfs_create_x32("RTCICR", 0644, reg_dir, reg_p + 0x07);


    set_rtc_alarm();

    return 0;
}

static void __exit rtc_exit(void)
{
    if (rtc_root) {
        debugfs_remove_recursive(rtc_root);
    }

    free_irq(39, NULL);
    cdev_del(rtc_cdev);
    unregister_chrdev_region(devno, 1);
}

module_init(rtc_init);
module_exit(rtc_exit);
MODULE_LICENSE("GPL");

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13. 通过 debugfs 导出 RTC 调试接口

#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/cdev.h>
#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>

typedef volatile struct {
    unsigned int  RTCDR;    /* +0x00: data register */
    unsigned int  RTCMR;    /* +0x04: match register */
    unsigned int  RTCLR;    /* +0x08: load register */
    unsigned int  RTCCR;    /* +0x0C: control register */
    unsigned int  RTCIMSC;  /* +0x10: interrupt mask set and clear register*/
    unsigned int  RTCRIS;   /* +0x14: raw interrupt status register*/
    unsigned int  RTCMIS;   /* +0x18: masked interrupt status register */
    unsigned int  RTCICR;   /* +0x1C: interrupt clear register */
} rtc_reg_t;

struct rtc_time {
    unsigned int year;
    unsigned int mon;
    unsigned int day;
    unsigned int hour;
    unsigned int min;
    unsigned int sec;
};

#define RTC_BASE 0x10017000

#define CUR_TIME_CMD   1      /* command for set/get current time */
#define ALARM_TIME_CMD 2      /* command for set/get alarm time */

static volatile rtc_reg_t *regs = NULL;
static unsigned long cur_time = 0;   /* current time */
static unsigned long alarm_time = 0; /* alarm time  */
static struct rtc_time tm; /* global time */
static char rtc_buf[64]; /* buffer for time string input from user space */

static void rtc_time_to_tm(unsigned long time)
{
    tm.hour = (time % 86400) / 3600;
    tm.min  = (time % 3600) / 60;
    tm.sec = time % 60;
}

static void rtc_tm_to_time(unsigned long *time)
{
    *time = tm.hour * 3600 + tm.min * 60 + tm.sec;
}

static void rtc_string_to_tm(void)
{
    tm.hour = (rtc_buf[0] - '0') * 10 + (rtc_buf[1] - '0');
    tm.min  = (rtc_buf[2] - '0') * 10 + (rtc_buf[3] - '0');
    tm.sec  = (rtc_buf[4] - '0') * 10 + (rtc_buf[5] - '0');
}

static void rtc_tm_to_string(void)
{
    rtc_buf[0] = tm.hour / 10 + '0';
    rtc_buf[1] = tm.hour % 10 + '0';
    rtc_buf[2] = tm.min / 10 + '0';
    rtc_buf[3] = tm.min % 10 + '0';
    rtc_buf[4] = tm.sec / 10 + '0';
    rtc_buf[5] = tm.sec % 10 + '0';
    rtc_buf[6] = '\n';
    rtc_buf[7] = '\0';
}


static dev_t devno;
static struct cdev *rtc_cdev;

static int rtc_open(struct inode *inode, struct file *fp)
{
    return 0;
}

static int rtc_release(struct inode *inode, struct file *fp)
{
    return 0;
}

static ssize_t rtc_read(struct file *fp, char __user *buf, 
                           size_t size, loff_t *pos)
{
    cur_time = regs->RTCDR;
    rtc_time_to_tm(cur_time);
    if (copy_to_user(buf, &tm, sizeof(struct rtc_time)) != 0){
        printk("rtc_read error!\n");
        return -1;
    }

    return sizeof(struct rtc_time);
}

static ssize_t rtc_write(struct file *fp, const char __user *buf, 
                            size_t size, loff_t *pos)
{
    int len = 0;
    
    len = sizeof(struct rtc_time);
    if (copy_from_user(&tm, buf, len) != 0) {
        printk("rtc_write error!\n");
        return -1;
    }
    rtc_tm_to_time(&cur_time);
    regs->RTCLR = cur_time;

    return len;
}

/* standard file I/O system call */
static const struct file_operations rtc_fops = {
    .owner   = THIS_MODULE,
    .read    = rtc_read,
    .write   = rtc_write,
    .open    = rtc_open,
    .release = rtc_release,
};

static void set_rtc_alarm(void)
{
    unsigned int tmp = 0;
    
    tmp = regs->RTCCR;
    tmp = tmp & 0xFFFFFFFE;
    regs->RTCCR = tmp;

    cur_time = regs->RTCDR;
    regs->RTCMR = alarm_time;

    regs->RTCICR = 1;
    regs->RTCIMSC = 1; // <------

    tmp = regs->RTCCR;
    tmp = tmp | 0x1;
    regs->RTCCR = tmp;
}

static irqreturn_t rtc_alarm_handler(int irq, void *dev_id)
{
    cur_time = regs->RTCDR;
    rtc_time_to_tm(cur_time);
    printk("\nalarm: beep~ beep~ \n");
    printk("\n    %d:%d:%d\n", tm.hour, tm.min, tm.sec);
    regs->RTCICR = 1;

    return IRQ_HANDLED;
}

static ssize_t rtc_debugfs_read(struct file *filp, char __user *buf,
                                size_t count, loff_t *ppos, int cmd)
{
    int ret;

    if (*ppos >= 64)
        return 0;
    if (*ppos + count > 64)
        count = 64 - *ppos;

    if (cmd == CUR_TIME_CMD) {
        cur_time = regs->RTCDR;
        rtc_time_to_tm(cur_time);
    }

    if (cmd == ALARM_TIME_CMD) {
        alarm_time = regs->RTCMR;
        rtc_time_to_tm(alarm_time);
    }

    rtc_tm_to_string();

    ret = copy_to_user(buf, rtc_buf, count);
    if (ret)
        return -EFAULT;
   *ppos += count;

    return count;
}

static ssize_t rtc_debugfs_write(struct file *filp, const char __user *buf, 
                                     size_t count, loff_t *ppos, int cmd)
{
    int ret;
    
    if (*ppos > 64)
        return 0;
    if (*ppos + count > 64)
        count = 64 - *ppos;
    
    ret = copy_from_user(rtc_buf, buf, count);
    if (ret)
        return -EFAULT;
    *ppos += count;

    rtc_string_to_tm();

    if (cmd == CUR_TIME_CMD) {
        rtc_tm_to_time(&cur_time);
        regs->RTCLR = cur_time;
    }

    if (cmd == ALARM_TIME_CMD) {
        rtc_tm_to_time(&alarm_time);
        set_rtc_alarm();
    }

    return count;
}


/* set current time interface */
static ssize_t rtc_cur_time_read(struct file *filp, char __user *buf, 
                                     size_t count, loff_t *ppos)
{
    return rtc_debugfs_read(filp, buf, count, ppos, CUR_TIME_CMD);
}

static ssize_t rtc_cur_time_write(struct file *filp, const char __user *buf, 
                                     size_t count, loff_t *ppos)
{
    return rtc_debugfs_write(filp, buf, count, ppos, CUR_TIME_CMD);
}

static const struct file_operations rtc_cur_time_fops = {
    .read    = rtc_cur_time_read,
    .write   = rtc_cur_time_write,
};


/* set alarm time interface */
static ssize_t rtc_alarm_time_read(struct file *filp, char __user *buf, 
                                     size_t count, loff_t *ppos)
{
    return rtc_debugfs_read(filp, buf, count, ppos, ALARM_TIME_CMD);
}

static ssize_t rtc_alarm_time_write(struct file *filp, const char __user *buf, 
                                     size_t count, loff_t *ppos)
{
    return rtc_debugfs_write(filp, buf, count, ppos, ALARM_TIME_CMD);
}

static const struct file_operations rtc_alarm_time_fops = {
    .read    = rtc_alarm_time_read,
    .write   = rtc_alarm_time_write,
};


static struct dentry *rtc_root;
static struct dentry *reg_dir;
static u32 *reg_p = NULL;

static int __init rtc_init(void)
{
    int ret = 0;
    
    regs = (rtc_reg_t *)ioremap(RTC_BASE, sizeof(rtc_reg_t));
    printk("rtc_init\n");

    ret = alloc_chrdev_region(&devno, 0, 1, "rtc-demo");
    if (ret) {
        printk("alloc char device number failed!\n");
        return ret;
    }
    printk("RTC devnum:%d minornum:%d\n", MAJOR(devno), MINOR(devno));

    rtc_cdev = cdev_alloc();
    cdev_init(rtc_cdev, &rtc_fops);

    ret = cdev_add(rtc_cdev, devno, 1);
    if (ret < 0) {
        printk("cdev_add failed..\n");
        return -ret;
    } else {
        printk("Register char module: rtc success!\n");
    }
    
    ret = request_irq(39, rtc_alarm_handler, 0, "rtc-test", NULL);
    if (ret == -1) {
        printk("request_irq failed!\n");
        return -ret;
    }

    rtc_root = debugfs_create_dir("rtc", NULL);
    if (IS_ERR(rtc_root)) {
        pr_err("%s: create rtc dir failed\n", __func__);
        return PTR_ERR(rtc_root);
    }
    reg_dir = debugfs_create_dir("reg_list", rtc_root);
    if (IS_ERR(reg_dir)) {
        pr_err("%s: create reg dir failed\n", __func__);
        return PTR_ERR(reg_dir);
    }

    reg_p = (u32 *)regs;
    debugfs_create_x32("RTCDR", 0644, reg_dir, reg_p);
    debugfs_create_x32("RTCMR", 0644, reg_dir, reg_p + 0x01);
    debugfs_create_x32("RTCLR", 0644, reg_dir, reg_p + 0x02);
    debugfs_create_x32("RTCCR", 0644, reg_dir, reg_p + 0x03);
    debugfs_create_x32("RTCIMSC", 0644, reg_dir, reg_p + 0x04);
    debugfs_create_x32("RTCRIS", 0644, reg_dir, reg_p + 0x05);
    debugfs_create_x32("RTCMIS", 0644, reg_dir, reg_p + 0x06);
    debugfs_create_x32("RTCICR", 0644, reg_dir, reg_p + 0x07);

    debugfs_create_file("cur_time", 0644, rtc_root, NULL, &rtc_cur_time_fops);
    debugfs_create_file("alarm_time", 0644, rtc_root, NULL, &rtc_alarm_time_fops);
    
    return 0;
}

static void __exit rtc_exit(void)
{
    if (rtc_root) {
        debugfs_remove_recursive(rtc_root);
    }

    free_irq(39, NULL);
    cdev_del(rtc_cdev);
    unregister_chrdev_region(devno, 1);
}

module_init(rtc_init);
module_exit(rtc_exit);
MODULE_LICENSE("GPL");

在这里插入图片描述
在这里插入图片描述

标签：struct,rtc,debugfs,08,static,root,hello
From： https://blog.csdn.net/weixin_36098975/article/details/141615174

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