硬件渠道：FL2440（S3C2440）
内核版别：Linux 2.6.28
主机渠道：Ubuntu 11.04
内核版别：Linux 2.6.39
穿插编译器版别：arm-linux-gcc 3.4.1
原创著作，转载请标明出处http://blog.csdn.net/yming0221/article/details/6584285
1、实时时钟概述
实时时钟（RTC）单元能够在断电的状况下运用扣子电池持续计时作业。RTC运用STRB/LDRB ARM操作传输二进制码十进制数的8位数据给CPU。其间的数据包含秒、分、时、日期、天、月、年的时刻信息。能够履行报警功用。
2、实时时钟操作
下面是RTC模块的电路图
3、RTC寄存器介绍
实时时钟操控寄存器（RTCCON）－REAL TIME CLOCK CONTROL REGISTER
节拍时刻计数寄存器（TICNT）－TICK TIME COUNT REGISTER
RTC报警操控寄存器（RTCALM）－RTC ALARM CONTROL REGISTER
报警秒数寄存器（ALMSEC）－ALARM SECOND DATA REGISTER
报警分钟计数寄存器（ALMMIN）－ALARM MIN DATA REGISTER
报警小时数据寄存器（ALMHOUR）－ALARM HOUR DATA REGISTER
报警日期数据寄存器（ALMDATE）－ALARM DATE DATA REGISTER
报警月数数据寄存器（ALMMON）－ALARM MON DATA REGISTER
报警年数数据寄存器（ALMYEAR）－ALARM YEAR DATA REGISTER
BCD数据寄存器的格局和报警寄存器结构相同，仅仅对应的地址不同。
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小时寄存器（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、驱动实例剖析
为了使驱动更简单了解，现在这个RTC驱动只完结了计时功用，没有增加相应的报警功用，也没有增加电源办理的功用，短少的功用往后完善。
下面先整体了解驱动：
首先是RTC驱动的结构体，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;};
驱动中界说对应的结构体
static struct platform_driver s3c2410_rtc_driver = {.probe = s3c_rtc_probe,//RTC勘探函数.remove = __devexit_p(s3c_rtc_remove),//RTC移除函数.driver = {.name = "s3c2410-rtc",.owner = THIS_MODULE,},};
下面是驱动中驱动的初始化和退出函数
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()函数在/drivers/base/platform.c中完结的。
能够看出，platform_driver_register()函数的效果便是为platform_driver中的driver中的probe、remove等供给接口函数
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);//注册老的驱动}
void platform_driver_unregister(struct platform_driver *drv){driver_unregister(&drv->driver);}
接下来是RTC渠道驱动勘探函数s3c_rtc_probe,下面函数界说的时分运用了__devinit的效果是使编译器优化代码，将其放在和是的内存方位，削减内存占用和进步内核功率。
probe函数接收到plarform_device这个参数后，就需求从中提取出需求的信息。它一般会经过调用内核供给的platform_get_resource和platform_get_irq等函数来取得相关信息。如经过platform_get_resource取得设备的开始地址后，能够对其进行request_mem_region和ioremap等操作，以便应用程序对其进行操作。经过platform_get_irq得到设备的中止号今后，就能够调用request_irq函数来向体系请求中止。这些操作在设备驱动程序中一般都要完结。
static int __devinit s3c_rtc_probe(struct platform_device *pdev){struct rtc_device *rtc;//界说rtc_device结构体，界说在/include/linux/rtc.hstruct resource *res;//界说资源结构体，界说在/include/linux/ioport.hint ret;pr_debug("%s: probe=%p\n", __func__, pdev);/* find the IRQs */s3c_rtc_tickno = platform_get_irq(pdev, 1);//在体系界说的渠道设备中获取中止号if (s3c_rtc_tickno < 0) {//反常处理dev_err(&pdev->dev, "no irq for rtc tick\n");return -ENOENT;}/* get the memory region */res = platform_get_resource(pdev, IORESOURCE_MEM, 0);//获取RTC渠道运用的IO资源if (res == NULL) {dev_err(&pdev->dev, "failed to get memory region resource\n");return -ENOENT;}//请求内存区域，res是struct resource类型，见本函数后边s3c_rtc_mem = request_mem_region(res->start,res->end-res->start+1,pdev->name);if (s3c_rtc_mem == NULL) {//请求内存犯错dev_err(&pdev->dev, "failed to reserve memory region\n");ret = -ENOENT;goto err_nores;}//将寄存器地址映射成虚拟地址，以便拜访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);//对RTCCON寄存器设置，概况见下面的函数完结pr_debug("s3c2410_rtc: RTCCON=%02x\n",readb(s3c_rtc_base + S3C2410_RTCCON));s3c_rtc_setfreq(&pdev->dev, 1);//概况见下面的函数完结/* register RTC and exit */rtc = rtc_device_register("s3c", &pdev->dev, &s3c_rtcops,THIS_MODULE);//注册RTC为RTC设备，其间s3c_rtcops界说见下if (IS_ERR(rtc)) {dev_err(&pdev->dev, "cannot attach rtc\n");ret = PTR_ERR(rtc);goto err_nortc;}rtc->max_user_freq = 128;//设置RTC节拍时刻计数寄存器TICNT的节拍时刻计数值的用户最大相对值//将RTC类的设备数据传递给体系设备，在/include/linux/platform_device.h中
//#define platform_set_drvdata(_dev,data) dev_set_drvdata(&(_dev)->dev, (data))，该函数在/include/linux/device.h中界说，见本函数下面
platform_set_drvdata(pdev, rtc);
return 0;
//反常处理err_nortc:s3c_rtc_enable(pdev, 0);iounmap(s3c_rtc_base);err_nomap:release_resource(s3c_rtc_mem);err_nores:return ret;}
下面是/include/linux/ioport.h中struct resource结构体界说
struct resource {resource_size_t start;resource_size_t end;const char *name;unsigned long flags;struct resource *parent, *sibling, *child;};
这是dev_set_drvdata()的函数界说：
static inline void dev_set_drvdata(struct device *dev, void *data){dev->driver_data = data;}
接下来是在s3c_rtc_probe()函数用到的两个函数s3c_rtc_enable()和s3c_rtc_setfreq()
static void s3c_rtc_enable(struct platform_device *pdev, int en){
void __iomem *base = s3c_rtc_base;//__iomem的效果便是为了使编译器更好的优化编译unsigned int tmp;if (s3c_rtc_base == NULL)return;//en作为参数传递过来假如en==0,封闭电源前的状况if (!en) {tmp = readb(base + S3C2410_RTCCON);
writeb(tmp & ~S3C2410_RTCCON_RTCEN, base + S3C2410_RTCCON);//设置RTCCON寄存器，屏蔽RTC使能，能够参阅数据手册中寄存器的相关界说tmp = readb(base + S3C2410_TICNT);writeb(tmp & ~S3C2410_TICNT_ENABLE, base + S3C2410_TICNT);//设置TICNT寄存器，屏蔽节拍时刻中止使能} else {/* re-enable the device, and check it is ok *///en!=0的状况，表明体系复位，从头使能RTC驱动if ((readb(base+S3C2410_RTCCON) & S3C2410_RTCCON_RTCEN) == 0){//RTCCON第0位为0，将其设置为1，从头使能dev_info(&pdev->dev, "rtc disabled, re-enabling\n");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_CNTSEL\n");tmp = readb(base + S3C2410_RTCCON);writeb(tmp& ~S3C2410_RTCCON_CNTSEL, base+S3C2410_RTCCON);//设置RTCCON第2位为0，设置BCD计数为混合BCD计数}if ((readb(base + S3C2410_RTCCON) & S3C2410_RTCCON_CLKRST)){dev_info(&pdev->dev, "removing RTCCON_CLKRST\n");tmp = readb(base + S3C2410_RTCCON);writeb(tmp & ~S3C2410_RTCCON_CLKRST, base+S3C2410_RTCCON);//RTC时钟计数器复位}}}
static int s3c_rtc_setfreq(struct device *dev, int freq)//设定节拍时刻计数值{unsigned int tmp;spin_lock_irq(&s3c_rtc_pie_lock);//获取自旋锁，对资源互斥拜访tmp = readb(s3c_rtc_base + S3C2410_TICNT) & S3C2410_TICNT_ENABLE;//节拍时刻使能有用tmp |= (128 / freq)-1;writeb(tmp, s3c_rtc_base + S3C2410_TICNT);spin_unlock_irq(&s3c_rtc_pie_lock);//解锁return 0;}
接下来是RTC设备类的操作。
下面是rtc_class_ops是RTC设备类在RTC驱动中心部分中界说的对RTC设备类进行操作的结构体，相似字符设备在驱动中的file_operations对字符设备进行操作的意思。该结构体被界说在rtc.h中，对RTC的操作首要有翻开、封闭、设置或获取时刻、设置或获取报警、设置节拍时刻计数值等等，该结构体内接口函数的完结都在下面
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,};
RTC翻开设备函数s3c_rtc_open()
static int s3c_rtc_open(struct device *dev){struct platform_device *pdev = to_platform_device(dev);//从渠道设备中获取RTC设备类的数据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);//请求中止if (ret) {dev_err(dev, "IRQ%d error %d\n", s3c_rtc_tickno, ret);goto tick_err;}tick_err:return ret;}
RTC TICK节拍时刻中止服务程序
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;}
RTC封闭设备函数s3c_rtc_release()
static void s3c_rtc_release(struct device *dev){struct platform_device *pdev = to_platform_device(dev);//从渠道设备中获取RTC设备类的数据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);//函数界说见下面free_irq(s3c_rtc_tickno, rtc_dev);}
s3c_rtc_setpie()函数，该函数首要效果便是依据参数设置T%&&&&&%NT寄存器的最高位，参数为0，制止使能，参数为1，使能
static int s3c_rtc_setpie(struct device *dev, int enabled){unsigned int tmp;pr_debug("%s: pie=%d\n", __func__, enabled);spin_lock_irq(&s3c_rtc_pie_lock);tmp = readb(s3c_rtc_base + S3C2410_TICNT) & ~S3C2410_TICNT_ENABLE;//读取TICNT的值并将最高位清0if (enabled)tmp |= S3C2410_TICNT_ENABLE;writeb(tmp, s3c_rtc_base + S3C2410_TICNT);//写入核算后新的值spin_unlock_irq(&s3c_rtc_pie_lock);return 0;}
下面两个函数是设置和读取BCD寄存器的时刻，逻辑很简单，仅仅读取和设置相应寄存器的值
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/%02x\n",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/%02d\n",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 years\n");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;}
到这儿RTC驱动的计时功用完结，报警功用还没有完结。下面是这个驱动源代码
#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=%d\n", __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=%d\n", __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/%02x\n",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/%02d\n",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 years\n");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 %d\n", 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-enabling\n");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_CNTSEL\n");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_CLKRST\n");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=%p\n", __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 tick\n");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 resource\n");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 region\n");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=%02x\n",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 rtc\n");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 Electronics\n";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
make后在目录下生成rtc.ko驱动，使用NFS挂在到方针板，insmod rtc.ko驱动就能够加载，履行hwclock指令，检查是否能够读取硬件的RTC。
