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/
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# tree
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.
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|-- date
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|-- dev
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|-- device -> ../../../s3c64xx-rtc
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|-- hctosys
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|-- max_user_freq
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|-- name
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|-- since_epoch
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|-- subsystem -> ../../../../../class/rtc
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|-- time
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|-- uevent
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`-- wakealarm
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2 directories, 9 files
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat date
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2001-11-05
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat dev
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254:0
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat hctosys
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1
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat max_user_freq
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32768
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat name
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s3c
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat since_epoch
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1004971702
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat time
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14:48:26
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat uevent
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MAJOR=254
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MINOR=0
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DEVNAME=rtc0
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0# cat wakealarm
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root@OK6410:/sys/devices/platform/s3c64xx-rtc/rtc/rtc0#
/proc
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root@OK6410:~# cat /proc/driver/rtc
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rtc_time : 14:43:19
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rtc_date : 2001-11-05
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alrm_time : 20:41:27
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alrm_date : 2001-11-03
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alarm_IRQ : no
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alrm_pending : no
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update IRQ enabled : no
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periodic IRQ enabled : no
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periodic IRQ frequency : 1
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max user IRQ frequency : 32768
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24hr : yes
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periodic_IRQ : no
二. proc文件系统
s3c_rtc_probe
rtc_device_register
--> rtc_proc_add_device
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static const struct file_operations rtc_proc_fops = {
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.open = rtc_proc_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = rtc_proc_release,
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};
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void rtc_proc_add_device(struct rtc_device *rtc)
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{
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if (rtc->id == 0)
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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
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}
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
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static int rtc_proc_show(struct seq_file *seq, void *offset)
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{
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int err;
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struct rtc_device *rtc = seq->private;
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const struct rtc_class_ops *ops = rtc->ops;
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struct rtc_wkalrm alrm;
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struct rtc_time tm;
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err = rtc_read_time(rtc, &tm);
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if (err == 0) {
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seq_printf(seq, "rtc_time\t: %02d:%02d:%02d\n" "rtc_date\t: %04d-%02d-%02d\n",
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tm.tm_hour, tm.tm_min, tm.tm_sec, tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
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}
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err = rtc_read_alarm(rtc, &alrm);
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if (err == 0) {
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seq_printf(seq, "alrm_time\t: ");
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if ((unsigned int)alrm.time.tm_hour <= 24)
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seq_printf(seq, "%02d:", alrm.time.tm_hour);
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else
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seq_printf(seq, "**:");
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if ((unsigned int)alrm.time.tm_min <= 59)
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seq_printf(seq, "%02d:", alrm.time.tm_min);
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else
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seq_printf(seq, "**:");
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if ((unsigned int)alrm.time.tm_sec <= 59)
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seq_printf(seq, "%02d\n", alrm.time.tm_sec);
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else
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seq_printf(seq, "**\n");
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seq_printf(seq, "alrm_date\t: ");
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if ((unsigned int)alrm.time.tm_year <= 200)
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seq_printf(seq, "%04d-", alrm.time.tm_year + 1900);
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else
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seq_printf(seq, "****-");
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if ((unsigned int)alrm.time.tm_mon <= 11)
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seq_printf(seq, "%02d-", alrm.time.tm_mon + 1);
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else
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seq_printf(seq, "**-");
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if (alrm.time.tm_mday && (unsigned int)alrm.time.tm_mday <= 31)
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seq_printf(seq, "%02d\n", alrm.time.tm_mday);
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else
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seq_printf(seq, "**\n");
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seq_printf(seq, "alarm_IRQ\t: %s\n", alrm.enabled ? "yes" : "no");
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seq_printf(seq, "alrm_pending\t: %s\n", alrm.pending ? "yes" : "no");
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seq_printf(seq, "update IRQ enabled\t: %s\n", (rtc->uie_rtctimer.enabled) ? "yes" : "no");
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seq_printf(seq, "periodic IRQ enabled\t: %s\n", (rtc->pie_enabled) ? "yes" : "no");
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seq_printf(seq, "periodic IRQ frequency\t: %d\n", rtc->irq_freq);
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seq_printf(seq, "max user IRQ frequency\t: %d\n", rtc->max_user_freq);
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}
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seq_printf(seq, "24hr\t\t: yes\n");
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if (ops->proc)
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ops->proc(rtc->dev.parent, seq);
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return 0;
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}
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static int rtc_proc_open(struct inode *inode, struct file *file)
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{
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int ret;
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struct rtc_device *rtc = PDE(inode)->data;
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if (!try_module_get(THIS_MODULE))
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return -ENODEV;
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//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
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ret = single_open(file, rtc_proc_show, rtc); //调用rtc_proc_show显示
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if (ret)
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module_put(THIS_MODULE);
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return ret;
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}
三. sys文件系统
主要包括rtc与alarm
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rtc_init
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--> rtc_sysfs_init
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--> rtc_attrs
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--> rtc_sysfs_show_name
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rtc_sysfs_show_date
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rtc_sysfs_show_time
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rtc_sysfs_show_since_epoch
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rtc_sysfs_show_max_user_freq
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rtc_sysfs_set_max_user_freq
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rtc_sysfs_show_hctosys
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s3c_rtc_probe
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rtc_device_register
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rtc_sysfs_add_device
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--> device_create_file(&rtc->dev, &dev_attr_wakealarm);
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--> rtc_sysfs_show_wakealarm
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--> rtc_sysfs_set_wakealarm
1. class初始化过程
driver/rtc/class.c
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static int __init rtc_init(void) //完成申请设备号和初始化class结构体
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{
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rtc_class = class_create(THIS_MODULE, "rtc");
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rtc_class->suspend = rtc_suspend;
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rtc_class->resume = rtc_resume;
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rtc_sysfs_init(rtc_class); //set rtc_class->dev_attrs
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return 0;
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}
2. 设备注册并在/sys/class下生成文件
s3c_rtc_probe
--> rtc_device_register 中
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struct rtc_device *rtc_device_register()
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{
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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
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err = device_register(&rtc->dev); //注册设备
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rtc_sysfs_add_device(rtc); //调用device_create_file在sys/class/下产生文件
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}
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s3c_rtc_probe
--> rtc_device_register
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--> rtc_sysfs_add_device
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void rtc_sysfs_add_device(struct rtc_device *rtc)
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{
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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
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}
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
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static struct device_attribute rtc_attrs[] = {
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__ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL),
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__ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL),
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__ATTR(time, S_IRUGO, rtc_sysfs_show_time, NULL),
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__ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL),
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__ATTR(max_user_freq, S_IRUGO | S_IWUSR, rtc_sysfs_show_max_user_freq, rtc_sysfs_set_max_user_freq),
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__ATTR(hctosys, S_IRUGO, rtc_sysfs_show_hctosys, NULL),
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{ },
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};
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void __init rtc_sysfs_init(struct class *rtc_class)
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{
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rtc_class->dev_attrs = rtc_attrs;
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}
通过device_create_file创建的文件是: wakealarm
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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
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#include <linux/module.h> /* For module specific items */
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#include <linux/moduleparam.h> /* For new moduleparam's */
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#include <linux/types.h> /* For standard types (like size_t) */
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#include <linux/errno.h> /* For the -ENODEV/... values */
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#include <linux/kernel.h> /* For printk/panic/... */
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#include <linux/fs.h> /* For file operations */
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#include <linux/ioport.h> /* For io-port access */
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#include <linux/platform_device.h> /* For platform_driver framework */
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#include <linux/init.h> /* For __init/__exit/... */
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#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
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#include <linux/io.h> /* For inb/outb/... */
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#include <linux/device.h>
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#include <linux/sysfs.h>
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static struct class *class_test;
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static struct device dev_test;
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static void dev_test_release(struct device *dev)
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{ //避免卸载时的warning
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}
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static ssize_t rtc_sysfs_show_name(struct device *dev, struct device_attribute *attr, char *buf)
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{
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return sprintf(buf, "%s\n", "rtc_sys_show_name");
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}
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static ssize_t rtc_sysfs_show_date(struct device *dev, struct device_attribute *attr, char *buf)
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{ //因为函数是空的,所以在read时为read error
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}
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static ssize_t rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr, char *buf)
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{
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return sprintf(buf, "%s\n", "show_wakealarm");
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}
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static ssize_t rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr, const char *buf, size_t n)
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{
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}
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static struct device_attribute test_attrs[] =
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{
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__ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL),
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__ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL),
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{},
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};
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static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR, rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);
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int hello_init(void)
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{
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class_test = class_create(THIS_MODULE, "class_test"); //创建一个class
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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
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dev_test.class = class_test; //设置dev的class
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dev_test.release = dev_test_release; //加上这个要不在卸载时会有个warning
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dev_set_name(&dev_test, "dev_test_%d", 2); //给dev取个名
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device_register(&dev_test); //注册dev
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device_create_file(&dev_test, &dev_attr_wakealarm); //为dev创建file
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return 0;
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}
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void hello_exit(void)
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{
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device_unregister(&dev_test);
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device_remove_file(&dev_test, &dev_attr_wakealarm);
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class_destroy(class_test);
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}
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module_init(hello_init);
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module_exit(hello_exit);
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MODULE_AUTHOR("test");
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MODULE_LICENSE("GPL");
结果如下:
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root@OK6410:/work/hello# insmod ./hello.ko
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root@OK6410:/work/hello# ls /sys/class/class_test/dev_test_2/ //uevent与subsystem是自动生成的
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date name subsystem uevent wakealarm //创建了date name wakealarm三个文件
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root@OK6410:/work/hello# cat /sys/class/class_test/dev_test_2/date
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cat: read error
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root@OK6410:/work/hello# cat /sys/class/class_test/dev_test_2/name
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rtc_sys_show_name
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root@OK6410:/work/hello# cat /sys/class/class_test/dev_test_2/uevent
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root@OK6410:/work/hello# cat /sys/class/class_test/dev_test_2/wakealarm
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show_wakealarm
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