ARMLinux驅(qū)動(dòng)RTC(實(shí)時(shí)時(shí)鐘)驅(qū)動(dòng)分析

內(nèi)核版本：Linux 2.6.28

主機(jī)平臺(tái)：Ubuntu 11.04

內(nèi)核版本：Linux 2.6.39

交叉編譯器版本：arm-linux-gcc 3.4.1

原創(chuàng)作品，轉(zhuǎn)載請(qǐng)標(biāo)明出處http://blog.csdn.net/yming0221/article/details/6584285

1、實(shí)時(shí)時(shí)鐘概述

實(shí)時(shí)時(shí)鐘（RTC）單元可以在斷電的情況下使用紐扣電池繼續(xù)計(jì)時(shí)工作。RTC使用STRB/LDRB ARM操作傳輸二進(jìn)制碼十進(jìn)制數(shù)的8位數(shù)據(jù)給CPU。其中的數(shù)據(jù)包括秒、分、時(shí)、日期、天、月、年的時(shí)間信息?？梢詧?zhí)行報(bào)警功能。

2、實(shí)時(shí)時(shí)鐘操作

下面是RTC模塊的電路圖

3、RTC寄存器介紹

實(shí)時(shí)時(shí)鐘控制寄存器（RTCCON）－REAL TIME CLOCK CONTROL REGISTER

節(jié)拍時(shí)間計(jì)數(shù)寄存器（TICNT）－TICK TIME COUNT REGISTER

RTC報(bào)警控制寄存器（RTCALM）－RTC ALARM CONTROL REGISTER

報(bào)警秒數(shù)寄存器（ALMSEC）－ALARM SECOND DATA REGISTER

報(bào)警分鐘計(jì)數(shù)寄存器（ALMMIN）－ALARM MIN DATA REGISTER

報(bào)警小時(shí)數(shù)據(jù)寄存器（ALMHOUR）－ALARM HOUR DATA REGISTER

報(bào)警日期數(shù)據(jù)寄存器（ALMDATE）－ALARM DATE DATA REGISTER

報(bào)警月數(shù)數(shù)據(jù)寄存器（ALMMON）－ALARM MON DATA REGISTER

報(bào)警年數(shù)數(shù)據(jù)寄存器（ALMYEAR）－ALARM YEAR DATA REGISTER

BCD數(shù)據(jù)寄存器的格式和報(bào)警寄存器結(jié)構(gòu)相同，只是對(duì)應(yīng)的地址不同。

BCD秒寄存器（BCDSEC）－BCD SECOND REGISTER 地址：0x57000070(L)0x57000073(B)

BCD分寄存器（BCDMIN）－BCD MINUTE REGISTER 地址：0x57000074(L)0x57000077(B)

BCD小時(shí)寄存器（BCDHOUR）－BCD HOUR REGISTER 地址：0x57000078(L)0x5700007B(B)

BCD日期寄存器（BCDDATE）－BCD DATE REGISTER 地址：0x5700007C(L)0x5700007F(B)

BCD日寄存器（BCDDAY）－BCD DAY REGISTER 地址：0x57000080(L)0x57000083(B)

BCD月寄存器（BCDMON）－BCD MONTH REGISTER 地址：0x57000084(L)0x57000087(B)

BCD年寄存器（BCDYEAR）－BCD YEAR REGISTER 地址：0x57000088(L)0x5700008B(B)

4、驅(qū)動(dòng)實(shí)例分析

為了使驅(qū)動(dòng)更容易理解，現(xiàn)在這個(gè)RTC驅(qū)動(dòng)只完成了計(jì)時(shí)功能，沒有添加相應(yīng)的報(bào)警功能，也沒有添加電源管理的功能，缺少的功能今后完善。

下面先總體了解驅(qū)動(dòng)：

首先是RTC驅(qū)動(dòng)的結(jié)構(gòu)體，在/include/linux/platform_device.h中，如下

struct platform_driver {int (*probe)(struct platform_device *);int (*remove)(struct platform_device *);void (*shutdown)(struct platform_device *);int (*suspend)(struct platform_device *, pm_message_t state);int (*suspend_late)(struct platform_device *, pm_message_t state);int (*resume_early)(struct platform_device *);int (*resume)(struct platform_device *);struct pm_ext_ops *pm;struct device_driver driver;};

static struct platform_driver s3c2410_rtc_driver = {.probe		= s3c_rtc_probe,//RTC探測(cè)函數(shù).remove		= __devexit_p(s3c_rtc_remove),//RTC移除函數(shù).driver		= {.name	= "s3c2410-rtc",.owner	= THIS_MODULE,},};

static int __init s3c_rtc_init(void){printk(banner);return platform_driver_register(&s3c2410_rtc_driver);}static void __exit s3c_rtc_exit(void){platform_driver_unregister(&s3c2410_rtc_driver);}

platform_driver_register()和platform_driver_unregister()函數(shù)在/drivers/base/platform.c中實(shí)現(xiàn)的。

可以看出，platform_driver_register()函數(shù)的作用就是為platform_driver中的driver中的probe、remove等提供接口函數(shù)

int platform_driver_register(struct platform_driver *drv){drv->driver.bus = &platform_bus_type;if (drv->probe)drv->driver.probe = platform_drv_probe;if (drv->remove)drv->driver.remove = platform_drv_remove;if (drv->shutdown)drv->driver.shutdown = platform_drv_shutdown;if (drv->suspend)drv->driver.suspend = platform_drv_suspend;if (drv->resume)drv->driver.resume = platform_drv_resume;if (drv->pm)drv->driver.pm = &drv->pm->base;return driver_register(&drv->driver);//注冊(cè)老的驅(qū)動(dòng)}

void platform_driver_unregister(struct platform_driver *drv){driver_unregister(&drv->driver);}

接下來是RTC平臺(tái)驅(qū)動(dòng)探測(cè)函數(shù)s3c_rtc_probe,下面函數(shù)定義的時(shí)候使用了__devinit的作用是使編譯器優(yōu)化代碼，將其放在和是的內(nèi)存位置，減少內(nèi)存占用和提高內(nèi)核效率。

probe函數(shù)接收到plarform_device這個(gè)參數(shù)后，就需要從中提取出需要的信息。它一般會(huì)通過調(diào)用內(nèi)核提供的platform_get_resource和platform_get_irq等函數(shù)來獲得相關(guān)信息。如通過platform_get_resource獲得設(shè)備的起始地址后，可以對(duì)其進(jìn)行request_mem_region和ioremap等操作，以便應(yīng)用程序?qū)ζ溥M(jìn)行操作。通過platform_get_irq得到設(shè)備的中斷號(hào)以后，就可以調(diào)用request_irq函數(shù)來向系統(tǒng)申請(qǐng)中斷。這些操作在設(shè)備驅(qū)動(dòng)程序中一般都要完成。

static int __devinit s3c_rtc_probe(struct platform_device *pdev){struct rtc_device *rtc;//定義rtc_device結(jié)構(gòu)體，定義在/include/linux/rtc.hstruct resource *res;//定義資源結(jié)構(gòu)體，定義在/include/linux/ioport.hint ret;pr_debug("%s: probe=%pn", __func__, pdev);/* find the IRQs */s3c_rtc_tickno = platform_get_irq(pdev, 1);//在系統(tǒng)定義的平臺(tái)設(shè)備中獲取中斷號(hào)if (s3c_rtc_tickno < 0) {//異常處理dev_err(&pdev->dev, "no irq for rtc tickn");return -ENOENT;}/* get the memory region */res = platform_get_resource(pdev, IORESOURCE_MEM, 0);//獲取RTC平臺(tái)使用的IO資源if (res == NULL) {dev_err(&pdev->dev, "failed to get memory region resourcen");return -ENOENT;}//申請(qǐng)內(nèi)存區(qū)域，res是struct resource類型，見本函數(shù)后面s3c_rtc_mem = request_mem_region(res->start,res->end-res->start+1,pdev->name);if (s3c_rtc_mem == NULL) {//申請(qǐng)內(nèi)存出錯(cuò)dev_err(&pdev->dev, "failed to reserve memory regionn");ret = -ENOENT;goto err_nores;}//將寄存器地址映射成虛擬地址，以便訪問s3c_rtc_base = ioremap(res->start, res->end - res->start + 1);if (s3c_rtc_base == NULL) {dev_err(&pdev->dev, "failed ioremap()n");ret = -EINVAL;goto err_nomap;}/* check to see if everything is setup correctly */s3c_rtc_enable(pdev, 1);//對(duì)RTCCON寄存器設(shè)置，詳情見下面的函數(shù)實(shí)現(xiàn)pr_debug("s3c2410_rtc: RTCCON=%02xn",readb(s3c_rtc_base + S3C2410_RTCCON));s3c_rtc_setfreq(&pdev->dev, 1);//詳情見下面的函數(shù)實(shí)現(xiàn)/* register RTC and exit */rtc = rtc_device_register("s3c", &pdev->dev, &s3c_rtcops,THIS_MODULE);//注冊(cè)RTC為RTC設(shè)備，其中s3c_rtcops定義見下if (IS_ERR(rtc)) {dev_err(&pdev->dev, "cannot attach rtcn");ret = PTR_ERR(rtc);goto err_nortc;}rtc->max_user_freq = 128;//設(shè)置RTC節(jié)拍時(shí)間計(jì)數(shù)寄存器TICNT的節(jié)拍時(shí)間計(jì)數(shù)值的用戶最大相對(duì)值//將RTC類的設(shè)備數(shù)據(jù)傳遞給系統(tǒng)設(shè)備，在/include/linux/platform_device.h中

//#define platform_set_drvdata(_dev,data)	dev_set_drvdata(&(_dev)->dev, (data))，該函數(shù)在/include/linux/device.h中定義，見本函數(shù)下面

platform_set_drvdata(pdev, rtc);

return 0;

//異常處理err_nortc:s3c_rtc_enable(pdev, 0);iounmap(s3c_rtc_base);err_nomap:release_resource(s3c_rtc_mem);err_nores:return ret;}

struct resource {resource_size_t start;resource_size_t end;const char *name;unsigned long flags;struct resource *parent, *sibling, *child;};

static inline void dev_set_drvdata(struct device *dev, void *data){dev->driver_data = data;}

static void s3c_rtc_enable(struct platform_device *pdev, int en){

void __iomem *base = s3c_rtc_base;//__iomem的作用就是為了使編譯器更好的優(yōu)化編譯unsigned int tmp;if (s3c_rtc_base == NULL)return;//en作為參數(shù)傳遞過來如果en==0,關(guān)閉電源前的情況if (!en) {tmp = readb(base + S3C2410_RTCCON);

writeb(tmp & ~S3C2410_RTCCON_RTCEN, base + S3C2410_RTCCON);//設(shè)置RTCCON寄存器，屏蔽RTC使能，可以參考數(shù)據(jù)手冊(cè)中寄存器的相關(guān)定義tmp = readb(base + S3C2410_TICNT);writeb(tmp & ~S3C2410_TICNT_ENABLE, base + S3C2410_TICNT);//設(shè)置TICNT寄存器，屏蔽節(jié)拍時(shí)間中斷使能} else {/* re-enable the device, and check it is ok *///en!=0的情況，表示系統(tǒng)復(fù)位，重新使能RTC驅(qū)動(dòng)if ((readb(base+S3C2410_RTCCON) & S3C2410_RTCCON_RTCEN) == 0){//RTCCON第0位為0，將其設(shè)置為1，重新使能dev_info(&pdev->dev, "rtc disabled, re-enablingn");tmp = readb(base + S3C2410_RTCCON);writeb(tmp|S3C2410_RTCCON_RTCEN, base+S3C2410_RTCCON);}if ((readb(base + S3C2410_RTCCON) & S3C2410_RTCCON_CNTSEL)){dev_info(&pdev->dev, "removing RTCCON_CNTSELn");tmp = readb(base + S3C2410_RTCCON);writeb(tmp& ~S3C2410_RTCCON_CNTSEL, base+S3C2410_RTCCON);//設(shè)置RTCCON第2位為0，設(shè)置BCD計(jì)數(shù)為混合BCD計(jì)數(shù)}if ((readb(base + S3C2410_RTCCON) & S3C2410_RTCCON_CLKRST)){dev_info(&pdev->dev, "removing RTCCON_CLKRSTn");tmp = readb(base + S3C2410_RTCCON);writeb(tmp & ~S3C2410_RTCCON_CLKRST, base+S3C2410_RTCCON);//RTC時(shí)鐘計(jì)數(shù)器復(fù)位}}}

static int s3c_rtc_setfreq(struct device *dev, int freq)//設(shè)定節(jié)拍時(shí)間計(jì)數(shù)值{unsigned int tmp;spin_lock_irq(&s3c_rtc_pie_lock);//獲取自旋鎖，對(duì)資源互斥訪問tmp = readb(s3c_rtc_base + S3C2410_TICNT) & S3C2410_TICNT_ENABLE;//節(jié)拍時(shí)間使能有效tmp |= (128 / freq)-1;writeb(tmp, s3c_rtc_base + S3C2410_TICNT);spin_unlock_irq(&s3c_rtc_pie_lock);//解鎖return 0;}

下面是rtc_class_ops是RTC設(shè)備類在RTC驅(qū)動(dòng)核心部分中定義的對(duì)RTC設(shè)備類進(jìn)行操作的結(jié)構(gòu)體，類似字符設(shè)備在驅(qū)動(dòng)中的file_operations對(duì)字符設(shè)備進(jìn)行操作的意思。該結(jié)構(gòu)體被定義在rtc.h中，對(duì)RTC的操作主要有打開、關(guān)閉、設(shè)置或獲取時(shí)間、設(shè)置或獲取報(bào)警、設(shè)置節(jié)拍時(shí)間計(jì)數(shù)值等等，該結(jié)構(gòu)體內(nèi)接口函數(shù)的實(shí)現(xiàn)都在下面

static const struct rtc_class_ops s3c_rtcops = {.open		= s3c_rtc_open,.release	= s3c_rtc_release,.read_time	= s3c_rtc_gettime,.set_time	= s3c_rtc_settime,.irq_set_freq	= s3c_rtc_setfreq,.irq_set_state	= s3c_rtc_setpie,};

static int s3c_rtc_open(struct device *dev){struct platform_device *pdev = to_platform_device(dev);//從平臺(tái)設(shè)備中獲取RTC設(shè)備類的數(shù)據(jù)struct rtc_device *rtc_dev = platform_get_drvdata(pdev);int ret;ret = request_irq(s3c_rtc_tickno, s3c_rtc_tickirq,IRQF_DISABLED,  "s3c2410-rtc tick", rtc_dev);//申請(qǐng)中斷if (ret) {dev_err(dev, "IRQ%d error %dn", s3c_rtc_tickno, ret);goto tick_err;}tick_err:return ret;}

static irqreturn_t s3c_rtc_tickirq(int irq, void *id){struct rtc_device *rdev = id;rtc_update_irq(rdev, 1, RTC_PF | RTC_IRQF);return IRQ_HANDLED;}

static void s3c_rtc_release(struct device *dev){struct platform_device *pdev = to_platform_device(dev);//從平臺(tái)設(shè)備中獲取RTC設(shè)備類的數(shù)據(jù)struct rtc_device *rtc_dev = platform_get_drvdata(pdev);/* do not clear AIE here, it may be needed for wake */s3c_rtc_setpie(dev, 0);//函數(shù)定義見下面free_irq(s3c_rtc_tickno, rtc_dev);}

static int s3c_rtc_setpie(struct device *dev, int enabled){unsigned int tmp;pr_debug("%s: pie=%dn", __func__, enabled);spin_lock_irq(&s3c_rtc_pie_lock);tmp = readb(s3c_rtc_base + S3C2410_TICNT) & ~S3C2410_TICNT_ENABLE;//讀取TICNT的值并將最高位清0if (enabled)tmp |= S3C2410_TICNT_ENABLE;writeb(tmp, s3c_rtc_base + S3C2410_TICNT);//寫入計(jì)算后新的值spin_unlock_irq(&s3c_rtc_pie_lock);return 0;}

static int s3c_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm){unsigned int have_retried = 0;void __iomem *base = s3c_rtc_base;retry_get_time:rtc_tm->tm_min  = readb(base + S3C2410_RTCMIN);rtc_tm->tm_hour = readb(base + S3C2410_RTCHOUR);rtc_tm->tm_mday = readb(base + S3C2410_RTCDATE);rtc_tm->tm_mon  = readb(base + S3C2410_RTCMON);rtc_tm->tm_year = readb(base + S3C2410_RTCYEAR);rtc_tm->tm_sec  = readb(base + S3C2410_RTCSEC);/* the only way to work out wether the system was mid-update* when we read it is to check the second counter, and if it* is zero, then we re-try the entire read*/if (rtc_tm->tm_sec == 0 && !have_retried) {have_retried = 1;goto retry_get_time;}pr_debug("read time %02x.%02x.%02x %02x/%02x/%02xn",rtc_tm->tm_year, rtc_tm->tm_mon, rtc_tm->tm_mday,rtc_tm->tm_hour, rtc_tm->tm_min, rtc_tm->tm_sec);rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);rtc_tm->tm_year += 100;rtc_tm->tm_mon -= 1;return 0;}static int s3c_rtc_settime(struct device *dev, struct rtc_time *tm){void __iomem *base = s3c_rtc_base;int year = tm->tm_year - 100;pr_debug("set time %02d.%02d.%02d %02d/%02d/%02dn",tm->tm_year, tm->tm_mon, tm->tm_mday,tm->tm_hour, tm->tm_min, tm->tm_sec);/* we get around y2k by simply not supporting it */if (year < 0 || year >= 100) {dev_err(dev, "rtc only supports 100 yearsn");return -EINVAL;}writeb(bin2bcd(tm->tm_sec),  base + S3C2410_RTCSEC);writeb(bin2bcd(tm->tm_min),  base + S3C2410_RTCMIN);writeb(bin2bcd(tm->tm_hour), base + S3C2410_RTCHOUR);writeb(bin2bcd(tm->tm_mday), base + S3C2410_RTCDATE);writeb(bin2bcd(tm->tm_mon + 1), base + S3C2410_RTCMON);writeb(bin2bcd(year), base + S3C2410_RTCYEAR);return 0;}

#include #include #include #include #include #include interrupt.h>#include #include #include #include #include #include #include #include #include static struct resource *s3c_rtc_mem;static void __iomem *s3c_rtc_base;static int s3c_rtc_tickno  = NO_IRQ;static DEFINE_SPINLOCK(s3c_rtc_pie_lock);static irqreturn_t s3c_rtc_tickirq(int irq, void *id){struct rtc_device *rdev = id;rtc_update_irq(rdev, 1, RTC_PF | RTC_IRQF);return IRQ_HANDLED;}/* Update control registers */static void s3c_rtc_setaie(int to){unsigned int tmp;pr_debug("%s: aie=%dn", __func__, to);tmp = readb(s3c_rtc_base + S3C2410_RTCALM) & ~S3C2410_RTCALM_ALMEN;if (to)tmp |= S3C2410_RTCALM_ALMEN;writeb(tmp, s3c_rtc_base + S3C2410_RTCALM);}static int s3c_rtc_setpie(struct device *dev, int enabled){unsigned int tmp;pr_debug("%s: pie=%dn", __func__, enabled);spin_lock_irq(&s3c_rtc_pie_lock);tmp = readb(s3c_rtc_base + S3C2410_TICNT) & ~S3C2410_TICNT_ENABLE;if (enabled)tmp |= S3C2410_TICNT_ENABLE;writeb(tmp, s3c_rtc_base + S3C2410_TICNT);spin_unlock_irq(&s3c_rtc_pie_lock);return 0;}static int s3c_rtc_setfreq(struct device *dev, int freq){unsigned int tmp;spin_lock_irq(&s3c_rtc_pie_lock);tmp = readb(s3c_rtc_base + S3C2410_TICNT) & S3C2410_TICNT_ENABLE;tmp |= (128 / freq)-1;writeb(tmp, s3c_rtc_base + S3C2410_TICNT);spin_unlock_irq(&s3c_rtc_pie_lock);return 0;}/* Time read/write */static int s3c_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm){unsigned int have_retried = 0;void __iomem *base = s3c_rtc_base;retry_get_time:rtc_tm->tm_min  = readb(base + S3C2410_RTCMIN);rtc_tm->tm_hour = readb(base + S3C2410_RTCHOUR);rtc_tm->tm_mday = readb(base + S3C2410_RTCDATE);rtc_tm->tm_mon  = readb(base + S3C2410_RTCMON);rtc_tm->tm_year = readb(base + S3C2410_RTCYEAR);rtc_tm->tm_sec  = readb(base + S3C2410_RTCSEC);/* the only way to work out wether the system was mid-update* when we read it is to check the second counter, and if it* is zero, then we re-try the entire read*/if (rtc_tm->tm_sec == 0 && !have_retried) {have_retried = 1;goto retry_get_time;}pr_debug("read time %02x.%02x.%02x %02x/%02x/%02xn",rtc_tm->tm_year, rtc_tm->tm_mon, rtc_tm->tm_mday,rtc_tm->tm_hour, rtc_tm->tm_min, rtc_tm->tm_sec);rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);rtc_tm->tm_year += 100;rtc_tm->tm_mon -= 1;return 0;}static int s3c_rtc_settime(struct device *dev, struct rtc_time *tm){void __iomem *base = s3c_rtc_base;int year = tm->tm_year - 100;pr_debug("set time %02d.%02d.%02d %02d/%02d/%02dn",tm->tm_year, tm->tm_mon, tm->tm_mday,tm->tm_hour, tm->tm_min, tm->tm_sec);/* we get around y2k by simply not supporting it */if (year < 0 || year >= 100) {dev_err(dev, "rtc only supports 100 yearsn");return -EINVAL;}writeb(bin2bcd(tm->tm_sec),  base + S3C2410_RTCSEC);writeb(bin2bcd(tm->tm_min),  base + S3C2410_RTCMIN);writeb(bin2bcd(tm->tm_hour), base + S3C2410_RTCHOUR);writeb(bin2bcd(tm->tm_mday), base + S3C2410_RTCDATE);writeb(bin2bcd(tm->tm_mon + 1), base + S3C2410_RTCMON);writeb(bin2bcd(year), base + S3C2410_RTCYEAR);return 0;}static int s3c_rtc_open(struct device *dev){struct platform_device *pdev = to_platform_device(dev);struct rtc_device *rtc_dev = platform_get_drvdata(pdev);int ret;ret = request_irq(s3c_rtc_tickno, s3c_rtc_tickirq,IRQF_DISABLED,  "s3c2410-rtc tick", rtc_dev);if (ret) {dev_err(dev, "IRQ%d error %dn", s3c_rtc_tickno, ret);goto tick_err;}tick_err:return ret;}static void s3c_rtc_release(struct device *dev){struct platform_device *pdev = to_platform_device(dev);struct rtc_device *rtc_dev = platform_get_drvdata(pdev);/* do not clear AIE here, it may be needed for wake */s3c_rtc_setpie(dev, 0);free_irq(s3c_rtc_tickno, rtc_dev);}static const struct rtc_class_ops s3c_rtcops = {.open		= s3c_rtc_open,.release	= s3c_rtc_release,.read_time	= s3c_rtc_gettime,.set_time	= s3c_rtc_settime,.irq_set_freq	= s3c_rtc_setfreq,.irq_set_state	= s3c_rtc_setpie,};static void s3c_rtc_enable(struct platform_device *pdev, int en){void __iomem *base = s3c_rtc_base;unsigned int tmp;if (s3c_rtc_base == NULL)return;if (!en) {tmp = readb(base + S3C2410_RTCCON);writeb(tmp & ~S3C2410_RTCCON_RTCEN, base + S3C2410_RTCCON);tmp = readb(base + S3C2410_TICNT);writeb(tmp & ~S3C2410_TICNT_ENABLE, base + S3C2410_TICNT);} else {/* re-enable the device, and check it is ok */if ((readb(base+S3C2410_RTCCON) & S3C2410_RTCCON_RTCEN) == 0){dev_info(&pdev->dev, "rtc disabled, re-enablingn");tmp = readb(base + S3C2410_RTCCON);writeb(tmp|S3C2410_RTCCON_RTCEN, base+S3C2410_RTCCON);}if ((readb(base + S3C2410_RTCCON) & S3C2410_RTCCON_CNTSEL)){dev_info(&pdev->dev, "removing RTCCON_CNTSELn");tmp = readb(base + S3C2410_RTCCON);writeb(tmp& ~S3C2410_RTCCON_CNTSEL, base+S3C2410_RTCCON);}if ((readb(base + S3C2410_RTCCON) & S3C2410_RTCCON_CLKRST)){dev_info(&pdev->dev, "removing RTCCON_CLKRSTn");tmp = readb(base + S3C2410_RTCCON);writeb(tmp & ~S3C2410_RTCCON_CLKRST, base+S3C2410_RTCCON);}}}static int __devexit s3c_rtc_remove(struct platform_device *dev){struct rtc_device *rtc = platform_get_drvdata(dev);platform_set_drvdata(dev, NULL);rtc_device_unregister(rtc);s3c_rtc_setpie(&dev->dev, 0);s3c_rtc_setaie(0);iounmap(s3c_rtc_base);release_resource(s3c_rtc_mem);kfree(s3c_rtc_mem);return 0;}static int __devinit s3c_rtc_probe(struct platform_device *pdev){struct rtc_device *rtc;struct resource *res;int ret;pr_debug("%s: probe=%pn", __func__, pdev);/* find the IRQs */s3c_rtc_tickno = platform_get_irq(pdev, 1);if (s3c_rtc_tickno < 0) {dev_err(&pdev->dev, "no irq for rtc tickn");return -ENOENT;}/* get the memory region */res = platform_get_resource(pdev, IORESOURCE_MEM, 0);if (res == NULL) {dev_err(&pdev->dev, "failed to get memory region resourcen");return -ENOENT;}s3c_rtc_mem = request_mem_region(res->start,res->end-res->start+1,pdev->name);if (s3c_rtc_mem == NULL) {dev_err(&pdev->dev, "failed to reserve memory regionn");ret = -ENOENT;goto err_nores;}s3c_rtc_base = ioremap(res->start, res->end - res->start + 1);if (s3c_rtc_base == NULL) {dev_err(&pdev->dev, "failed ioremap()n");ret = -EINVAL;goto err_nomap;}/* check to see if everything is setup correctly */s3c_rtc_enable(pdev, 1);pr_debug("s3c2410_rtc: RTCCON=%02xn",readb(s3c_rtc_base + S3C2410_RTCCON));s3c_rtc_setfreq(&pdev->dev, 1);/* register RTC and exit */rtc = rtc_device_register("s3c", &pdev->dev, &s3c_rtcops,THIS_MODULE);if (IS_ERR(rtc)) {dev_err(&pdev->dev, "cannot attach rtcn");ret = PTR_ERR(rtc);goto err_nortc;}rtc->max_user_freq = 128;platform_set_drvdata(pdev, rtc);return 0;err_nortc:s3c_rtc_enable(pdev, 0);iounmap(s3c_rtc_base);err_nomap:release_resource(s3c_rtc_mem);err_nores:return ret;}static struct platform_driver s3c2410_rtc_driver = {.probe		= s3c_rtc_probe,.remove		= __devexit_p(s3c_rtc_remove),.driver		= {.name	= "s3c2410-rtc",.owner	= THIS_MODULE,},};static char __initdata banner[] = "S3C24XX RTC, (c) 2004,2006 Simtec Electronicsn";static int __init s3c_rtc_init(void){printk(banner);return platform_driver_register(&s3c2410_rtc_driver);}static void __exit s3c_rtc_exit(void){platform_driver_unregister(&s3c2410_rtc_driver);}module_init(s3c_rtc_init);module_exit(s3c_rtc_exit);MODULE_DESCRIPTION("My s3c2440 RTC Driver");MODULE_AUTHOR("YanMing - yming0221@gmail.com");MODULE_LICENSE("GPL");MODULE_ALIAS("platform:s3c2410-rtc");

Makefile文件

obj-m := rtc.oKERNELDIR ?= /arm/linux-2.6.28.7-2440PWD := $(shell pwd)default:$(MAKE) -C $(KERNELDIR) M=$(PWD) modulesclean:rm -f *.o *.ko *.order *.symvers