RTC时钟驱动
Linux-2.6.32.2内核自带RTC驱动，但mach_smdk2440.c中没有添加该设备集，因此没有被激活，加入该平台设备，RTC平台设备定义在arch/arm/plat-s3c24xx/devs.c。
static struct platform_device *smdk2440_devices[] __initdata = {
&s3c_device_usb, /* arch/arm/mach-s3c2440/mach-smdk2440.c */
&s3c_device_lcd,
&s3c_device_wdt,
&s3c_device_i2c0,
&s3c_device_iis,
&s3c_device_rtc,
};
驱动实现：
#include <linux/module.h>#include <linux/fs.h>#include <linux/string.h>#include <linux/init.h>#include <linux/platform_device.h>#include <linux/interrupt.h>#include <linux/rtc.h>#include <linux/bcd.h>#include <linux/clk.h>#include <linux/log2.h>
#include <mach/hardware.h>#include <asm/uaccess.h>#include <asm/io.h>#include <asm/irq.h>#include <plat/regs-rtc.h>
/* I have yet to find an S3C implementation with more than one* of these rtc blocks in */
static struct resource *s3c_rtc_mem;
static void __iomem *s3c_rtc_base;static int s3c_rtc_alarmno = NO_IRQ;static int s3c_rtc_tickno = NO_IRQ;
static DEFINE_SPINLOCK(s3c_rtc_pie_lock);
/* IRQ Handlers */
static irqreturn_t s3c_rtc_alarmirq(int irq, void *id){struct rtc_device *rdev = id;
/* 报警中断到来时，设定报警相关信息，函数实现位于drivers/rtc/interface.c */rtc_update_irq(rdev, 1, RTC_AF | RTC_IRQF);return IRQ_HANDLED;}
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 设置RTCALM全局报警使能位*/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);}
/* 节拍时间计数器使能 */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;
if (enabled)tmp |= S3C2410_TICNT_ENABLE;
writeb(tmp, s3c_rtc_base + S3C2410_TICNT);spin_unlock_irq(&s3c_rtc_pie_lock);
return 0;}
/* 节拍时间计数值设置*/static int s3c_rtc_setfreq(struct device *dev, int freq){unsigned int tmp;
if (!is_power_of_2(freq))return -EINVAL;
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 *//* 读取RTC中时间：分、时、日期、月、年、秒 */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 *//* 如果读到秒为0，可能有进位，根据2440手册知道，要重新读一次 */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);
/* 将BCD码转换为二进制数 */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);
/*这里为什么要加100年和减1月,查看数据手册得知区别1900年和2000年闰年的因素,1900年不是闰年而2000年是闰年*/rtc_tm->tm_year += 100;rtc_tm->tm_mon -= 1;
return 0;}
/* 与s3c_rtc_gettime功能相反 */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;}
/* 读取RTC报警时间值 */static int s3c_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm){struct rtc_time *alm_tm = &alrm->time;void __iomem *base = s3c_rtc_base;unsigned int alm_en;
alm_tm->tm_sec = readb(base + S3C2410_ALMSEC);alm_tm->tm_min = readb(base + S3C2410_ALMMIN);alm_tm->tm_hour = readb(base + S3C2410_ALMHOUR);alm_tm->tm_mon = readb(base + S3C2410_ALMMON);alm_tm->tm_mday = readb(base + S3C2410_ALMDATE);alm_tm->tm_year = readb(base + S3C2410_ALMYEAR);
alm_en = readb(base + S3C2410_RTCALM);
alrm->enabled = (alm_en & S3C2410_RTCALM_ALMEN) ? 1 : 0;
pr_debug("read alarm %02x %02x.%02x.%02x %02x/%02x/%02x\n", alm_en, alm_tm->tm_year, alm_tm->tm_mon, alm_tm->tm_mday, alm_tm->tm_hour, alm_tm->tm_min, alm_tm->tm_sec);
/* decode the alarm enable field */
if (alm_en & S3C2410_RTCALM_SECEN)alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);elsealm_tm->tm_sec = 0xff;
if (alm_en & S3C2410_RTCALM_MINEN)alm_tm->tm_min = bcd2bin(alm_tm->tm_min);elsealm_tm->tm_min = 0xff;
if (alm_en & S3C2410_RTCALM_HOUREN)alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);elsealm_tm->tm_hour = 0xff;
if (alm_en & S3C2410_RTCALM_DAYEN)alm_tm->tm_mday = bcd2bin(alm_tm->tm_mday);elsealm_tm->tm_mday = 0xff;
if (alm_en & S3C2410_RTCALM_MONEN) {alm_tm->tm_mon = bcd2bin(alm_tm->tm_mon);alm_tm->tm_mon -= 1; //这里减1有待研究，为什么只有月没有年减1} else {alm_tm->tm_mon = 0xff;}
if (alm_en & S3C2410_RTCALM_YEAREN)alm_tm->tm_year = bcd2bin(alm_tm->tm_year);elsealm_tm->tm_year = 0xffff;
return 0;}/* 与s3c_rtc_getalarm功能相反 */static int s3c_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm){struct rtc_time *tm = &alrm->time;void __iomem *base = s3c_rtc_base;unsigned int alrm_en;
pr_debug("s3c_rtc_setalarm: %d, %02x/%02x/%02x %02x.%02x.%02x\n", alrm->enabled, tm->tm_mday & 0xff, tm->tm_mon & 0xff, tm->tm_year & 0xff, tm->tm_hour & 0xff, tm->tm_min & 0xff, tm->tm_sec);
alrm_en = readb(base + S3C2410_RTCALM) & S3C2410_RTCALM_ALMEN;writeb(0x00, base + S3C2410_RTCALM);
if (tm->tm_sec < 60 && tm->tm_sec >= 0) {alrm_en |= S3C2410_RTCALM_SECEN;writeb(bin2bcd(tm->tm_sec), base + S3C2410_ALMSEC);}
if (tm->tm_min < 60 && tm->tm_min >= 0) {alrm_en |= S3C2410_RTCALM_MINEN;writeb(bin2bcd(tm->tm_min), base + S3C2410_ALMMIN);}
if (tm->tm_hour < 24 && tm->tm_hour >= 0) {alrm_en |= S3C2410_RTCALM_HOUREN;writeb(bin2bcd(tm->tm_hour), base + S3C2410_ALMHOUR);}
pr_debug("setting S3C2410_RTCALM to %08x\n", alrm_en);
writeb(alrm_en, base + S3C2410_RTCALM);
s3c_rtc_setaie(alrm->enabled);
/*根据全局报警使能的状态来决定是唤醒RTC报警中断还是睡眠RTC报警中断*/if (alrm->enabled)enable_irq_wake(s3c_rtc_alarmno);elsedisable_irq_wake(s3c_rtc_alarmno);
return 0;}
static int s3c_rtc_proc(struct device *dev, struct seq_file *seq){unsigned int ticnt = readb(s3c_rtc_base + S3C2410_TICNT);
seq_printf(seq, "periodic_IRQ\t: %s\n", (ticnt & S3C2410_TICNT_ENABLE) ? "yes" : "no" );return 0;}
/*RTC设备类打开接口函数*/static int s3c_rtc_open(struct device *dev){/*这里主要的目的是从系统平台设备中获取RTC设备类的数据，和RTC探测函数rtc_probe中 的platform_set_drvdata(pdev, rtc)的操作刚好相反。定义在platform_device.h中*/struct platform_device *pdev = to_platform_device(dev);struct rtc_device *rtc_dev = platform_get_drvdata(pdev);int ret;
ret = request_irq(s3c_rtc_alarmno, s3c_rtc_alarmirq, IRQF_DISABLED, "s3c2410-rtc alarm", rtc_dev);
if (ret) {dev_err(dev, "IRQ%d error %d\n", s3c_rtc_alarmno, ret);return 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;}
return ret;
tick_err:free_irq(s3c_rtc_alarmno, rtc_dev);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_alarmno, rtc_dev);free_irq(s3c_rtc_tickno, rtc_dev);}
/*rtc_class_ops是RTC设备类在RTC驱动核心部分中定义的对RTC设备类进行操作的结构体， 类似字符设备在驱动中的file_operations对字符设备进行操作的意思。该结构体被定义 在include/linux/rtc.h中，对RTC的操作主要有打开、关闭、设置或获取时间、设置或 获取报警、设置节拍时间计数值等等，该结构体内接口函数的实现在前面*/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,.read_alarm= s3c_rtc_getalarm,.set_alarm= s3c_rtc_setalarm,.irq_set_freq= s3c_rtc_setfreq,.irq_set_state= s3c_rtc_setpie,.proc = s3c_rtc_proc,};
/* 控制RTCCON寄存器，rtc使能 */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); /*注销RTC设备类*/
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;}
s3c_rtc_alarmno = platform_get_irq(pdev, 0);if (s3c_rtc_alarmno < 0) {dev_err(&pdev->dev, "no irq for alarm\n");return -ENOENT;}
pr_debug("s3c2410_rtc: tick irq %d, alarm irq %d\n", s3c_rtc_tickno, s3c_rtc_alarmno);
/* 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);
device_init_wakeup(&pdev->dev, 1); //驱动支持电源管理
/* register RTC and exit *//*将RTC注册为RTC设备类，RTC设备类在RTC驱动核心部分中由系统定义好的，注意rtcops这个参数是一个结构体，该结构体的作用和里面的接口函数前面实现。rtc_device_register函数在rtc.h中定义，在drivers/rtc/class.c中实现*/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;
/*将RTC设备类的数据传递给系统平台设备。platform_set_drvdata是定义在platform_device.h的宏，如下： #define platform_set_drvdata(_dev,data) dev_set_drvdata(&(_dev)->dev, (data)) 而dev_set_drvdata又被定义在include/linux/device.h中，如下： static inline void dev_set_drvdata (struct device *dev, void *data) { dev->driver_data = data; }*/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;}
#ifdef CONFIG_PM
/* RTC Power management control */
static int ticnt_save;
static int s3c_rtc_suspend(struct platform_device *pdev, pm_message_t state){/* save TICNT for anyone using periodic interrupts */ticnt_save = readb(s3c_rtc_base + S3C2410_TICNT);s3c_rtc_enable(pdev, 0);return 0;}
static int s3c_rtc_resume(struct platform_device *pdev){s3c_rtc_enable(pdev, 1);writeb(ticnt_save, s3c_rtc_base + S3C2410_TICNT);return 0;}#else#define s3c_rtc_suspend NULL#define s3c_rtc_resume NULL#endif
static struct platform_driver s3c2410_rtc_driver = {.probe= s3c_rtc_probe,.remove= __devexit_p(s3c_rtc_remove),.suspend= s3c_rtc_suspend,.resume= s3c_rtc_resume,.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); //注册RTC平台驱动}
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("Samsung S3C RTC Driver");MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");MODULE_LICENSE("GPL");MODULE_ALIAS("platform:s3c2410-rtc");
配置内核，加入RTC驱动支持
Devide drivers —>
<*> Real Time Clock —>
<*> Samsung S3C series SoC RTC
测试：
# cat /proc/devices 查看rtc设备号
# ls –l /dev/rtc
crw-r–r– 1 root root 254, 0 Jan 1 1970 /dev/rtc
lrwxr–r– 1 root root 3Jan 1 1970 /dev/rtc0 -> rtc
date –s 072021352011 设置系统时间为2011-07-20 21:35
hwclock –w 把刚设置的系统时间存入RTC
开机时使用hwclock –s把RTC时间恢复到系统时间
hwclock参数说明：
Options:
-r Show hardware clock time
-s Set system time from hardware clock
-w Set hardware clock to system time
-u Hardware clock is in UTC
-l Hardware clock is in local time
-f FILE Use specified device (e.g. /dev/rtc2)
然后继续努力，把让自己跌倒的石头搬掉或绕过去，不就解决问题了吗
