S3C2440驱动篇—RTC驱动分析
S3C2440驱动篇—RTC驱动分析
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);
- else
- alm_tm->tm_sec = 0xff;
- if (alm_en & S3C2410_RTCALM_MINEN)
- alm_tm->tm_min = bcd2bin(alm_tm->tm_min);
- else
- alm_tm->tm_min = 0xff;
- if (alm_en & S3C2410_RTCALM_HOUREN)
- alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);
- else
- alm_tm->tm_hour = 0xff;
- if (alm_en & S3C2410_RTCALM_DAYEN)
- alm_tm->tm_mday = bcd2bin(alm_tm->tm_mday);
- else
- alm_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);
- else
- alm_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);
- else
- disable_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)
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