s3c6410 RTC driver——读取实时时间信息

开发环境：Ubuntu 14.0

开发板内核版本：Linux 3.0

The Real Time Clock (RTC) unit can be operated by the backup battery when the system power is off. The data include the time by second, minute, hour, date, day, month, and year. The RTC unit works with an external 32.768 KHz crystal and can perform the alarm function.

下面是RTC相关的18个寄存器

在头文件中的定义

在mach/map.h里面

自己定义一个header file 方便使用(一层封装的思想)

EOF_rtc.h

/**************************************************
code writer :   EOF
code date   :   2014.08.26
e-mail      :   jasonleaster@gmail.comcode purpose:This header file is used for ...It's convenient to use this MACRO but not
address number directly.**************************************************/
#ifndef _EOF_RTC_H
#define _EOF_RTC_H#include <mach/map.h> /* for 'S3C64XX_PA_RTC' */#define RTC_CON       (S3C64XX_PA_RTC + 0x40)#define RTC_SECOND_REG  (S3C64XX_PA_RTC + 0x70)
#define RTC_MINUTE_REG  (S3C64XX_PA_RTC + 0x74)
#define RTC_HOUR_REG    (S3C64XX_PA_RTC + 0x78)
#define RTC_DATE_REG    (S3C64XX_PA_RTC + 0x7C)
#define RTC_DAY_REG (S3C64XX_PA_RTC + 0x80)
#define RTC_MONTH_REG   (S3C64XX_PA_RTC + 0x84)
#define RTC_YEAR_REG    (S3C64XX_PA_RTC + 0x88)/*
** second minute hour day month and year.
** There are six messages waited to be read.
*/
#define MESSAGE     6#define DEVICE_NAME    "rtc_time"
/*
**  create four device for fun, demo for one driver but drive different devices
*/
#define DEVICE_NUM  1
#define PORT_NUM    36
#define RTC_PORT_BASE   S3C64XX_PA_RTC#define RTC_MAJOR 0 /*by dynamical *//*
**  It's fantastic to use a structure to abstract a device!
*/
struct rtc_dev
{struct cdev cdev;struct mutex mutex;/*** used for storing time message */int buf[1024];
};#endif

rtc_time.c

/************************************************************
code writer :   EOF
code date   :   2014.08.26
e-mail      :   jasonleaster@gmail.com
code file   :   rtc_time.ccode purpose:This is code is for RTC-driver in s3c6410-ARM.#BUG-1! 2014.08.27  afternoonI am sorry about there is a bug waited to be fixed up.When we print out the "day-message", we can't get the
right one.It always print out digital number '1'.I don't know
what happens...If you could fix it up, please touch me by e-mail.
Thank you.@BUG-1 fixed upI mixed up with DATE and DAY in register.Now it work
correctly.If you still find something wrong with my code, please
touch me. Thank you.************************************************************/#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>#include <linux/cdev.h>      /* for 'struct cdev'*/
#include <linux/kdev_t.h> /* for 'MAJOR MINOR' */
#include <linux/fs.h>
#include <linux/kernel.h> /* for 'printk()' */
#include <linux/slab.h>       /* for 'kmalloc()'*/
#include <linux/types.h>  /* for 'ssize_t'*/
#include <linux/proc_fs.h>
#include <asm/io.h>       /* for 'inl & outl'*/
#include <asm/uaccess.h>  /* for 'copy_to_user'*/
#include <linux/ioport.h> /* for 'request_region()' 'ioremap()' */#include <linux/device.h> /* for 'struct class'*/#include "EOF_rtc.h"#define DEBUGunsigned int rtc_major  =  RTC_MAJOR;
unsigned int rtc_minor  =  0;unsigned long t_msg_addr[MESSAGE] =
{RTC_SECOND_REG,RTC_MINUTE_REG,RTC_HOUR_REG,RTC_DATE_REG,RTC_MONTH_REG,RTC_YEAR_REG
};module_param(rtc_major,int,S_IRUGO);
module_param(rtc_minor,int,S_IRUGO);MODULE_AUTHOR("EOF");
MODULE_LICENSE("Dual BSD/GPL");/* allocated in 'void rtc_init(void)' */
struct rtc_dev* rtc_devices;
struct class* rtc_class;static int rtc_proc_show(char* buf,char** start,off_t offset,int count,int* eof,void* data)
{#ifdef DEBUGprintk(KERN_ALERT "calling rtc_proc_show...\n");
#endifchar k_output[1024];struct rtc_dev* dev = rtc_devices;int device_num = 0;int length = 0;int temp = 0;int foo  = 0;if(mutex_lock_interruptible(&dev->mutex)){return -ERESTARTSYS;}for(device_num = 0;device_num < DEVICE_NUM;device_num++){length += sprintf(k_output+length,"### rtc%d ###\n",device_num);for(temp = 0; temp < MESSAGE;temp++){foo = readl(ioremap(t_msg_addr[temp],sizeof(int)));length += sprintf(k_output+length," temp: %d time: %d\n",temp, ((foo & 0xF0)>>4)*10 + (foo & 0x0F) );}    }printk(KERN_ALERT "%s\n",k_output);*eof = 1;mutex_unlock(&dev->mutex);return 0;
}static void rtc_create_proc(void)
{struct proc_dir_entry * entry;entry    = create_proc_read_entry("rtc_reader",0,NULL,rtc_proc_show,NULL);if(!entry){printk(KERN_ALERT "line:%d 'proc_create_read_entry()' failed!\n",__LINE__);}
}static void rtc_remove_proc(void)
{remove_proc_entry("rtc_reader",NULL);
}ssize_t rtc_read(struct file* filp,char __user* buf,const size_t count,loff_t* f_pos)
{
#ifdef DEBUGprintk(KERN_ALERT "rtc_read ing... using ioremap...");
#endifstruct rtc_dev* dev = filp->private_data;int temp  = 0;int ret     = 0;if(mutex_lock_interruptible(&dev->mutex)){return -ERESTARTSYS;}else{
#ifdef DEBUGprintk(KERN_ALERT "Lock in rtc_read!\n");
#endif}for(temp = 0; temp < MESSAGE;temp++){/*** Hey,penguins...Attention! Do not use the physic address directly.** You shoult remap it into virtual addres by 'ioremap()'.*///dev->buf[temp] = inl(t_msg_addr[temp]);dev->buf[temp] = readl(ioremap(t_msg_addr[temp],sizeof(int)));
#ifdef DEBUGprintk(KERN_ALERT "dev->buf[%d] : %x\n",temp,dev->buf[temp]);
#endif} if((ret = copy_to_user(buf,dev->buf,count))){printk(KERN_ALERT "copy_to_user failed!\n");temp = temp - ret;goto out_read;}out_read:mutex_unlock(&dev->mutex);
#ifdef DEBUGprintk(KERN_ALERT "Lock released rtc_read!\n");
#endifreturn temp;
}ssize_t rtc_write(struct file* filp,const char __user* buf,size_t count,loff_t* f_ops)
{
#ifdef DEBUGprintk(KERN_ALERT "writing rtc ...\n");
#endifstruct rtc_dev* dev = filp->private_data;int ret = 0;int temp = 0;if(mutex_lock_interruptible(&dev->mutex)){return -ERESTARTSYS;}if((ret = copy_from_user(dev->buf,buf,sizeof(*(dev->buf)) * MESSAGE))){temp = temp - ret;goto out_write;}for(temp = 0; temp < MESSAGE;temp++){outl(dev->buf[temp],(ioremap(t_msg_addr[temp],sizeof(int))) );}  out_write:mutex_unlock(&dev->mutex);return 0;
}int rtc_open(struct inode* inode,struct file* filp)
{
#ifdef DEBUGprintk(KERN_ALERT "rtc_open ing...!\n");
#endifstruct rtc_dev* dev;dev = container_of(inode->i_cdev,struct rtc_dev,cdev);filp->private_data = dev;return 0;
}int rtc_release(struct inode * inode, struct file* filp)
{
#ifdef DEBUGprintk(KERN_ALERT "rtc Released!\n");
#endifreturn 0;
}struct file_operations rtc_fops =
{.owner =  THIS_MODULE,.read   =  rtc_read,/*** It's dangerous and unnecessory to write something into RTC's register, the company which created your 'RTC' have finished 'write-work'.Generally, you shouldn't change it.** But I also implement a method that how to write message** into RTC's register.*/.write   =  rtc_write,.open =  rtc_open,.release= rtc_release,
};static void rtc_setup_cdev(struct rtc_dev* dev,int indev)
{int err = 0;int dev_num = MKDEV(rtc_major,rtc_minor + indev);cdev_init(&dev->cdev,&rtc_fops);dev->cdev.owner  =  THIS_MODULE;dev->cdev.ops    =  &rtc_fops;err =  cdev_add(&dev->cdev,dev_num,1);if(err){printk(KERN_ALERT "Error in adding rtc%d, err value:%d\n",indev,err);}else{
#ifdef DEBUGprintk(KERN_ALERT "rtc_%d setted!\n",indev);
#endif}
}void rtc_clean(void)
{int temp = 0;dev_t    dev_num = 0;dev_num = MKDEV(rtc_major,rtc_minor);if(rtc_devices){for(temp = 0;temp > DEVICE_NUM;temp++){cdev_del(&rtc_devices[temp].cdev);device_destroy(rtc_class,MKDEV(MAJOR(dev_num),temp));
#ifdef DEBUGprintk(KERN_ALERT "rtc%d!\n",temp);
#endif}kfree(rtc_devices);}rtc_remove_proc();unregister_chrdev_region(dev_num,DEVICE_NUM);release_region(RTC_PORT_BASE,PORT_NUM);}int rtc_init(void)
{/* get our needed resource */if(!request_region(RTC_PORT_BASE,PORT_NUM,DEVICE_NAME)){printk(KERN_ALERT "rtc: can't request address:%p\n",(void*)RTC_PORT_BASE);return -ENODEV;}int ret = 0;int temp = 0;dev_t dev_num = 0;ret = alloc_chrdev_region(&dev_num,rtc_minor,DEVICE_NUM,DEVICE_NAME);rtc_major = MAJOR(dev_num);rtc_class = class_create(THIS_MODULE,DEVICE_NAME);if(ret < 0){printk(KERN_ALERT "rtc: can't get major %d\n",rtc_major);return ret;}/* allocate the device -- we can't have them static, as the number* can be specified at load time*/   rtc_devices = kmalloc(DEVICE_NUM*sizeof(struct rtc_dev),GFP_KERNEL);if(!rtc_devices){ret = -ENOMEM;goto fail;}memset(rtc_devices,0,DEVICE_NUM * sizeof(struct rtc_dev));/* Initialize the device */for(temp = 0;temp < DEVICE_NUM;temp++){mutex_init(&rtc_devices[temp].mutex);rtc_setup_cdev(&rtc_devices[temp],temp);device_create(rtc_class,NULL,(dev_num + temp),NULL,"rtc_%d",temp);}rtc_create_proc();#ifdef DEBUGprintk(KERN_ALERT "rtc registed!\n");
#endifreturn 0;fail:rtc_clean();return 0;
}module_init(rtc_init);
module_exit(rtc_clean);

测试程序

/*********************************************************************
code writer : EOF
code date : 2014.08.16
code file : rtc_test.c
e-mail    : jasonleaster@gmail.comcode purpose:This is a demo for user how to use RTC device driver.You should know that data store in RTC register as BCD-code.
If you want to represent it as deciminal, we could transform two-bits
BCD-code into deciminal number by this way:Deciminal number = ((BCD-code&0xF0)>>4)*10+(BCD-code)&0x0F;If there is something wrong with my code,
please touch me by e-mail. Thank you.*********************************************************************/#include <stdio.h>
#include <fcntl.h>int main()
{int buf[10];char output[BUFSIZ] = {0,};int fd = 0;int counter = 0;if((fd = open("/dev/rtc_0",O_RDONLY)) < 0){printf("open failed!\n");return 0;}if(read(fd,buf,sizeof(buf)) <= 0){printf("read failed\n");goto failed;}counter += sprintf(output+counter,"Time now: ");counter += sprintf(output+counter,"Year: 20%d ", ((buf[5]&0xF0)>>4)*10 + (buf[5]&0x0F));counter += sprintf(output+counter,"month: %d ",  ((buf[4]&0xF0)>>4)*10 + (buf[4]&0x0F));counter += sprintf(output+counter,"day: %d ",    ((buf[3]&0xF0)>>4)*10 + (buf[3]&0x0F));counter += sprintf(output+counter,"hour: %d ",   ((buf[2]&0xF0)>>4)*10 + (buf[2]&0x0F));counter += sprintf(output+counter,"minute: %d ", ((buf[1]&0xF0)>>4)*10 + (buf[1]&0x0F));counter += sprintf(output+counter,"second: %d\n",((buf[0]&0xF0)>>4)*10 + (buf[0]&0x0F));printf("%s\n",output);failed:close(fd);return 0;
}

和rtc_time.c里面注释说的一样，我遇到了一个BUG，目前还不知道怎么搞定他，如果高手路过恳请指导修正

很明显有一个有错的地方，今天是8月27日，但是他怎么都是print 8.1...

这里是date输出的结果和我直接debug打印结果(BCD玛)的对比

day对应的是dev->bug[3]，这里BCD码是1....

update: 2014.08.27 19:01:33

替换了最新的EOF_rtc.h 和rtc_time.c

修复了之前的“day-bug”

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s3c6410 RTC driver——读取实时时间信息 LDD3 ELDD 学习笔记

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