S3C6410使用---28rtc驱动中的文件处理

一. RTC中的文件
rtc中既在/proc又在/sys目录下存在可以修改属性的文件
/sys/class/rtc/rtc0/

root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# tree
.
|-- date
|-- dev
|-- device -> ../../../s3c64xx-rtc
|-- hctosys
|-- max_user_freq
|-- name
|-- since_epoch
|-- subsystem -> ../../../../../class/rtc
|-- time
|-- uevent
`-- wakealarm

2 directories, 9 files

root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat date
2001-11-05
root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat dev
254:0
root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat hctosys
1
root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat max_user_freq
32768
root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat name
s3c
root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat since_epoch
1004971702
root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat time
14:48:26
root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat uevent
MAJOR=254
MINOR=0
DEVNAME=rtc0
root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat wakealarm
root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0#

/proc

root@OK6410:~# cat /proc/driver/rtc
rtc_time : 14:43:19
rtc_date : 2001-11-05
alrm_time : 20:41:27
alrm_date : 2001-11-03
alarm_IRQ : no
alrm_pending : no
update IRQ enabled : no
periodic IRQ enabled : no
periodic IRQ frequency : 1
max user IRQ frequency : 32768
24hr : yes
periodic_IRQ : no

二. proc文件系统
s3c_rtc_probe
rtc_device_register    
   --> rtc_proc_add_device

static const struct file_operations rtc_proc_fops = {
    .open        = rtc_proc_open,
    .read        = seq_read,
    .llseek        = seq_lseek,
    .release    = rtc_proc_release,
};

void rtc_proc_add_device(struct rtc_device *rtc)
{
    if (rtc->id == 0)
        proc_create_data("driver/rtc", 0, NULL, &rtc_proc_fops, rtc);  //在/proc目录下创建 driver/rtc文件,文件操作是rtc_proc_fops
}

2. 打开读取/proc/driver/rtc 文件
s3c_rtc_probe
rtc_device_register    
   --> rtc_proc_add_device
        --> rtc_proc_open
            --> rtc_proc_show

static int rtc_proc_show(struct seq_file *seq, void *offset)
{
    int err;
    struct rtc_device *rtc = seq->private;
    const struct rtc_class_ops *ops = rtc->ops;
    struct rtc_wkalrm alrm;
    struct rtc_time tm;

    err = rtc_read_time(rtc, &tm);
    if (err == 0) {
        seq_printf(seq, "rtc_time\t: %02d:%02d:%02d\n" "rtc_date\t: %04d-%02d-%02d\n",
            tm.tm_hour, tm.tm_min, tm.tm_sec, tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
    }

    err = rtc_read_alarm(rtc, &alrm);
    if (err == 0) {
        seq_printf(seq, "alrm_time\t: ");
        if ((unsigned int)alrm.time.tm_hour <= 24)
            seq_printf(seq, "%02d:", alrm.time.tm_hour);
        else
            seq_printf(seq, "**:");
        if ((unsigned int)alrm.time.tm_min <= 59)
            seq_printf(seq, "%02d:", alrm.time.tm_min);
        else
            seq_printf(seq, "**:");
        if ((unsigned int)alrm.time.tm_sec <= 59)
            seq_printf(seq, "%02d\n", alrm.time.tm_sec);
        else
            seq_printf(seq, "**\n");

        seq_printf(seq, "alrm_date\t: ");
        if ((unsigned int)alrm.time.tm_year <= 200)
            seq_printf(seq, "%04d-", alrm.time.tm_year + 1900);
        else
            seq_printf(seq, "****-");
        if ((unsigned int)alrm.time.tm_mon <= 11)
            seq_printf(seq, "%02d-", alrm.time.tm_mon + 1);
        else
            seq_printf(seq, "**-");
        if (alrm.time.tm_mday && (unsigned int)alrm.time.tm_mday <= 31)
            seq_printf(seq, "%02d\n", alrm.time.tm_mday);
        else
            seq_printf(seq, "**\n");
        seq_printf(seq, "alarm_IRQ\t: %s\n", alrm.enabled ? "yes" : "no");
        seq_printf(seq, "alrm_pending\t: %s\n", alrm.pending ? "yes" : "no");
        seq_printf(seq, "update IRQ enabled\t: %s\n", (rtc->uie_rtctimer.enabled) ? "yes" : "no");
        seq_printf(seq, "periodic IRQ enabled\t: %s\n", (rtc->pie_enabled) ? "yes" : "no");
        seq_printf(seq, "periodic IRQ frequency\t: %d\n", rtc->irq_freq);
        seq_printf(seq, "max user IRQ frequency\t: %d\n", rtc->max_user_freq);
    }

    seq_printf(seq, "24hr\t\t: yes\n");

    if (ops->proc)
        ops->proc(rtc->dev.parent, seq);

    return 0;
}

static int rtc_proc_open(struct inode *inode, struct file *file)
{
    int ret;
    struct rtc_device *rtc = PDE(inode)->data;

    if (!try_module_get(THIS_MODULE))
        return -ENODEV;
    //single_open不太明白,网上说是打开和释放只有一条记录的文件,不知道这儿的一条是怎么算的
    ret = single_open(file, rtc_proc_show, rtc);    //调用rtc_proc_show显示
    if (ret)
        module_put(THIS_MODULE);
    return ret;
}

三. sys文件系统
主要包括rtc与alarm

rtc_init
    --> rtc_sysfs_init
    --> rtc_attrs
        --> rtc_sysfs_show_name
            rtc_sysfs_show_date
            rtc_sysfs_show_time
            rtc_sysfs_show_since_epoch
            rtc_sysfs_show_max_user_freq
            rtc_sysfs_set_max_user_freq
            rtc_sysfs_show_hctosys
s3c_rtc_probe
    rtc_device_register
    rtc_sysfs_add_device
    --> device_create_file(&rtc->dev, &dev_attr_wakealarm);
        --> rtc_sysfs_show_wakealarm
        --> rtc_sysfs_set_wakealarm

1. class初始化过程
driver/rtc/class.c

static int __init rtc_init(void) //完成申请设备号和初始化class结构体
{
    rtc_class = class_create(THIS_MODULE, "rtc");
    rtc_class->suspend = rtc_suspend;
    rtc_class->resume = rtc_resume;
    rtc_sysfs_init(rtc_class);     //set rtc_class->dev_attrs
    return 0;
}

2. 设备注册并在/sys/class下生成文件
s3c_rtc_probe
--> rtc_device_register 中

struct rtc_device *rtc_device_register()
{
    rtc->dev.class = rtc_class;         //设置s3c-rtc驱动的class是在driver/rtc/class.c中初始化好后的全局变量rtc_class
    err = device_register(&rtc->dev);   //注册设备
    rtc_sysfs_add_device(rtc);          //调用device_create_file在sys/class/下产生文件
}
s3c_rtc_probe
--> rtc_device_register
    -->  rtc_sysfs_add_device
void rtc_sysfs_add_device(struct rtc_device *rtc)
{
    err = device_create_file(&rtc->dev, &dev_attr_wakealarm); //这个函数可以在/sys/class下创建相应的属性文件
}

3. class创建的文件: 一个是属性创建,一个是通过device_create_file创建
通过rtc_class属性创建的文件是: name, data, time, since_epoch, max_user_freq, hctosys文件

static struct device_attribute rtc_attrs[] = {
    __ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL),
    __ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL),
    __ATTR(time, S_IRUGO, rtc_sysfs_show_time, NULL),
    __ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL),
    __ATTR(max_user_freq, S_IRUGO | S_IWUSR, rtc_sysfs_show_max_user_freq, rtc_sysfs_set_max_user_freq),
    __ATTR(hctosys, S_IRUGO, rtc_sysfs_show_hctosys, NULL),
    { },
};

void __init rtc_sysfs_init(struct class *rtc_class)
{
    rtc_class->dev_attrs = rtc_attrs;
}

通过device_create_file创建的文件是: wakealarm

static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR, rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);

四. 一个sys的测试程序

#include <linux/module.h>        /* For module specific items */
#include <linux/moduleparam.h>        /* For new moduleparam's */
#include <linux/types.h>        /* For standard types (like size_t) */
#include <linux/errno.h>        /* For the -ENODEV/... values */
#include <linux/kernel.h>        /* For printk/panic/... */
#include <linux/fs.h>            /* For file operations */
#include <linux/ioport.h>        /* For io-port access */
#include <linux/platform_device.h>    /* For platform_driver framework */
#include <linux/init.h>            /* For __init/__exit/... */
#include <linux/uaccess.h>        /* For copy_to_user/put_user/... */
#include <linux/io.h>            /* For inb/outb/... */
#include <linux/device.h>
#include <linux/sysfs.h>

static struct class *class_test;
static struct device dev_test;
static void dev_test_release(struct device *dev)
{  //避免卸载时的warning
}
static ssize_t rtc_sysfs_show_name(struct device *dev, struct device_attribute *attr, char *buf)
{
    return sprintf(buf, "%s\n", "rtc_sys_show_name");
}
static ssize_t rtc_sysfs_show_date(struct device *dev, struct device_attribute *attr, char *buf)
{  //因为函数是空的,所以在read时为read error
}
static ssize_t rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr, char *buf)
{
    return sprintf(buf, "%s\n", "show_wakealarm");
}

static ssize_t rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr, const char *buf, size_t n)
{
}

static struct device_attribute test_attrs[] =
{
    __ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL),
    __ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL),
    {},
};
static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR, rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);

int hello_init(void)
{
    class_test = class_create(THIS_MODULE, "class_test");   //创建一个class
    class_test->dev_attrs = test_attrs;                     //设置class的属性,如果只想创建device文件这步可以省略

    dev_test.class = class_test;                            //设置dev的class
    dev_test.release = dev_test_release;                  //加上这个要不在卸载时会有个warning
    dev_set_name(&dev_test, "dev_test_%d", 2);              //给dev取个名
    device_register(&dev_test);                             //注册dev

    device_create_file(&dev_test, &dev_attr_wakealarm);     //为dev创建file

    return 0;
}

void hello_exit(void)
{
    device_unregister(&dev_test);
    device_remove_file(&dev_test, &dev_attr_wakealarm);
    class_destroy(class_test);
}
module_init(hello_init);
module_exit(hello_exit);

MODULE_AUTHOR("test");
MODULE_LICENSE("GPL");

结果如下:

root@OK6410:/work/hello# insmod ./hello.ko
root@OK6410:/work/hello# ls /sys/class/class_test/dev_test_2/    //uevent与subsystem是自动生成的
    date name       subsystem  uevent     wakealarm                    //创建了date name wakealarm三个文件
root@OK6410:/work/hello# cat /sys/class/class_test/dev_test_2/date
    cat: read error
root@OK6410:/work/hello# cat /sys/class/class_test/dev_test_2/name
    rtc_sys_show_name
root@OK6410:/work/hello# cat /sys/class/class_test/dev_test_2/uevent
root@OK6410:/work/hello# cat /sys/class/class_test/dev_test_2/wakealarm
    show_wakealarm