久久婷婷香蕉热狠狠综合,精品无码国产自产拍在线观看蜜,寡妇房东在做爰3,中文字幕日本人妻久久久免费,国产成人精品三上悠亚久久

Linux的(de)RTC驅動相對(dui)還是(shi)比(bi)較(jiao)(jiao)簡單的(de)，可以將它作為(wei)一個普(pu)通(tong)的(de)字符型設備(bei)，或者一個misc設備(bei)，也可以是(shi)一個平臺設備(bei)，這(zhe)都沒有關(guan)系，主(zhu)要(yao)(yao)還是(shi)對(dui)rtc_ops這(zhe)個文件操作結構體中的(de)成員(yuan)填充(chong)，這(zhe)里(li)主(zhu)要(yao)(yao)涉(she)及到兩個方面比(bi)較(jiao)(jiao)重(zhong)要(yao)(yao)：

1. 在Linux中有硬件(jian)時(shi)鐘(zhong)(zhong)(zhong)(zhong)與系(xi)統(tong)(tong)時(shi)鐘(zhong)(zhong)(zhong)(zhong)等兩(liang)種時(shi)鐘(zhong)(zhong)(zhong)(zhong)。硬件(jian)時(shi)鐘(zhong)(zhong)(zhong)(zhong)是(shi)(shi)指主機板上(shang)的(de)時(shi)鐘(zhong)(zhong)(zhong)(zhong)設(she)備(bei)，也就(jiu)是(shi)(shi)通常可(ke)在BIOS畫面設(she)定(ding)的(de)時(shi)鐘(zhong)(zhong)(zhong)(zhong)。系(xi)統(tong)(tong)時(shi)鐘(zhong)(zhong)(zhong)(zhong)則是(shi)(shi)指kernel中的(de)時(shi)鐘(zhong)(zhong)(zhong)(zhong)。當Linux啟動時(shi)，系(xi)統(tong)(tong)時(shi)鐘(zhong)(zhong)(zhong)(zhong)會去(qu)讀(du)取硬件(jian)時(shi)鐘(zhong)(zhong)(zhong)(zhong)的(de)設(she)定(ding)，之后(hou)系(xi)統(tong)(tong)時(shi)鐘(zhong)(zhong)(zhong)(zhong)即(ji)獨(du)立運(yun)作。所有Linux相關(guan)指令與函(han)數都是(shi)(shi)讀(du)取系(xi)統(tong)(tong)時(shi)鐘(zhong)(zhong)(zhong)(zhong)的(de)設(she)定(ding)。

系統(tong)時(shi)鐘(zhong)(zhong)(zhong)的(de)(de)設定就(jiu)是(shi)我(wo)(wo)們(men)常(chang)用的(de)(de)date命(ming)令(ling)(ling)，而我(wo)(wo)們(men)寫的(de)(de)RTC驅動(dong)(dong)就(jiu)是(shi)為硬件時(shi)鐘(zhong)(zhong)(zhong)服務的(de)(de)，它有(you)屬于(yu)自己的(de)(de)命(ming)令(ling)(ling)hwclock，因此使(shi)用date命(ming)令(ling)(ling)是(shi)不可能調用到(dao)(dao)我(wo)(wo)們(men)的(de)(de)驅動(dong)(dong)的(de)(de)（在這點(dian)上開始把我(wo)(wo)郁悶到(dao)(dao)了，寫完驅動(dong)(dong)之后(hou)，傻傻的(de)(de)用date指令(ling)(ling)來測(ce)試，當然結果(guo)是(shi)什么都沒有(you)），我(wo)(wo)們(men)可以(yi)通過hwclock的(de)(de)一些指令(ling)(ling)來實現更(geng)新(xin)rtc時(shi)鐘(zhong)(zhong)(zhong)——也就(jiu)是(shi)系統(tong)時(shi)鐘(zhong)(zhong)(zhong)和硬件時(shi)鐘(zhong)(zhong)(zhong)的(de)(de)交(jiao)互。

hwclock –r顯(xian)示硬件時鐘與(yu)日期

hwclock –s將系統時鐘調整為與目前(qian)的硬(ying)件時鐘一(yi)致(zhi)。

hwclock –w將(jiang)硬件時鐘(zhong)(zhong)調(diao)整為與(yu)目前的(de)系統時鐘(zhong)(zhong)一(yi)致。

用戶(hu)輸入 hwclck -s // 這個命(ming)令是 把(ba)硬件(jian)的(de)時鐘更新到系(xi)統中去

這個命令會調用busybox源碼中的hwclock.c,在(zai)目錄util-linux/hwclock.c 中的 ->int hwclock_main(int argc UNUSED_PARAM, char **argv)

后面的參數會以argv形式接收

opt = getopt32(argv, "lurswtf:", &rtcname);
        會把argv的參數進行轉換 l -> 0x01
        u -> 0x02
        r -> 0x04
        s -> 0x08
        w -> 0x10
        t -> 0x20
        f -> 0x40 
        : -> 0x80
        #define HWCLOCK_OPT_LOCALTIME 0x01 
        #define HWCLOCK_OPT_UTC 0x02
        #define HWCLOCK_OPT_SHOW 0x04 // 等價 hwclock –r 顯示硬件的時間
        #define HWCLOCK_OPT_HCTOSYS 0x08 // 等價 hwclock –s 硬件時間更新到系統時間
        #define HWCLOCK_OPT_SYSTOHC 0x10 // 等價 hwclock –w 系統時間更新到硬件時間 
        #define HWCLOCK_OPT_SYSTZ 0x20
        #define HWCLOCK_OPT_RTCFILE 0x40
         if (opt & (HWCLOCK_OPT_UTC | HWCLOCK_OPT_LOCALTIME)) // 判斷是是否是 hwclock –l -u
         utc = (opt & HWCLOCK_OPT_UTC); 
         if (opt & HWCLOCK_OPT_HCTOSYS) // 判斷是是否是 hwclock –s
        to_sys_clock(&rtcname, utc);
        else if (opt & HWCLOCK_OPT_SYSTOHC) // 判斷是是否是 hwclock –w
        from_sys_clock(&rtcname, utc);
        else
        /* default HWCLOCK_OPT_SHOW */ // 默認是 hwclock –r 
        show_clock(&rtcname, utc);
        hwclock –s ->to_sys_clock-> read_rtc(pp_rtcname, NULL, utc); // 讀rtc的時間
        -> fd = rtc_xopen(pp_rtcname, O_RDONLY)
        *default_rtc = "/dev/rtc";
        rtc = open(*default_rtc, flags);
        *default_rtc = "/dev/rtc0";
        rtc = open(*default_rtc, flags);
        *default_rtc = "/dev/misc/rtc";
        // 會打開這幾個默認的文件
        -> rtc_read_tm(&tm_time, fd);
        -> xioctl(fd, RTC_RD_TIME, ptm);
        // 讀系統的時間
        -> settimeofday(&tv, &tz)) // 設置系統的時間
        hwclock –w ->from_sys_clock(&rtcname, utc); -> rtc = rtc_xopen(pp_rtcname, O_WRONLY);
        *default_rtc = "/dev/rtc";
        rtc = open(*default_rtc, flags);
        *default_rtc = "/dev/rtc0";
        rtc = open(*default_rtc, flags);
        *default_rtc = "/dev/misc/rtc";
        // 會打開這幾個默認的文件
        -> gettimeofday(&tv, NULL); // 獲得系統時間
        -> xioctl(rtc, RTC_SET_TIME, &tm_time); // 設置系統時間
        -> close(rtc) // 
        hwclock –r -> show_clock(const char **pp_rtcname, int utc) 
        -> time_t t = read_rtc(pp_rtcname, &sys_tv, utc);
        ->*default_rtc = "/dev/rtc";
        rtc = open(*default_rtc, flags);
        *default_rtc = "/dev/rtc0";
        rtc = open(*default_rtc, flags);
        *default_rtc = "/dev/misc/rtc";
        // 會打開這幾個默認的文件
        -> fd = rtc_xopen(pp_rtcname, O_RDONLY);
        -> rtc_read_tm(&tm_time, fd); 
        -> xioctl(fd, RTC_RD_TIME, ptm);

以上可以知道(dao), 讀時間使(shi)用(yong)ioctl進(jin)行的(de),使(shi)用(yong)兩個命令(ling)

RTC_RD_TIME // 讀時間
        RTC_SET_TIME // 設置時(shi)間

第二部(bu)分: rtc驅動(dong)架構(gou)分析

rtc的驅動架構是基于(yu)platform機(ji)制實現的,platform_device是由設備(bei)樹(shu)生成

rtc的(de)設(she)備樹如下:

rtc@10070000 
        {
                compatible = "samsung,s3c6410-rtc";
                reg = < 0x10070000 0x100>;
                interrupts = < 0 44 0>, <0 45 0>;
                clocks = < &clock 346>;
                clock-names = "rtc";
                status = "disabled";
         };

這個(ge)設備樹會生成platform_device

驅動(dong)在driver /rtc/rtc-s3c.c 文件中定(ding)義

static struct platform_driver s3c_rtc_driver = {
        .probe = s3c_rtc_probe,
        .remove = s3c_rtc_remove,
        .id_table = s3c_rtc_driver_ids,
        .driver = {
        .name = "s3c-rtc",
        .owner = THIS_MODULE,
        .pm = &s3c_rtc_pm_ops,
        .of_match_table = of_match_ptr(s3c_rtc_dt_match),
        },
        };
  &nbsp;     module_platform_driver(s3c_rtc_driver);

實(shi)現了(le)platform_driver s3c_rtc_driver的注(zhu)冊

設備樹中的compatible = "samsung,s3c6410-rtc";和驅(qu)動中的 .compatible = "samsung,s3c6410-rtc",名稱一直時(shi),會執行(xing)驅(qu)動的probe函數-> s3c_rtc_probe

在probe函數中注冊(ce)一(yi)個(ge)字符設備驅(qu)動

rtc = devm_rtc_device_register(&pdev->dev, "s3c", &s3c_rtcops, 
        -> rtc = rtc_device_register(name, dev, ops, owner);
        -> of_id = of_alias_get_id(dev->of_node, "rtc"); // 注冊一個rtc的類
        -> rtc_dev_prepare(rtc);
        -> cdev_init(&rtc->char_dev, &rtc_dev_fops);
        -> rtc_dev_add_device(rtc);
        -> if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
        -> rtc_sysfs_add_device(rtc); // 等價于 mknod /dev/rtc c 254 0
        -> s3c_rtc_gettime(NULL, &rtc_tm); // 獲(huo)得系統的時間

以上是一個(ge)字符(fu)設備的創建。

注冊了一個cdev結構體(ti)(ti)和file_operations結構體(ti)(ti)rtc_dev_fops

rtc_dev_fops實現如下:
        static const struct file_operations rtc_dev_fops = {
        .owner = THIS_MODULE,
        .llseek = no_llseek,
        .read = rtc_dev_read,
        .poll = rtc_dev_poll,
        .unlocked_ioctl = rtc_dev_ioctl,
        .open = rtc_dev_open,
        .release = rtc_dev_release,
        .fasync = rtc_dev_fasync,
      &nbsp; };

由以上(shang)可知 : 應用程序調用ioctl 驅動也調用ioctl

hwclock –w -> xioctl(fd, RTC_RD_TIME, ptm); -> rtc_dev_ioctl(命令) (用戶空間) (內核空間)
        -> case RTC_RD_TIME:rtc_read_time(rtc, &tm);
  &nbsp;     if (copy_to_user(uarg, &tm, sizeof(tm)))

由以上可知 : 應用程序(xu)調用ioctl 驅動(dong)也(ye)調用ioctl

hwclock –s -> xioctl(fd, RTC_SET_TIME, ptm); -> rtc_dev_ioctl(命令) (用戶空間) (內核空間) 
        -> case RTC_SET_TIME: 
        if (copy_from_user(&tm, uarg, sizeof(tm)))
        return rtc_set_time(rtc, &tm);
        hwclock –r -> xioctl(fd, RTC_RD_TIME , ptm); -> rtc_dev_ioctl(命令) (用戶空間) (內核空間) 
        -> case RTC_RD_TIME: rtc_read_time(rtc, &tm);
        if (copy_to_user(uarg, &tm, sizeof(tm)))