NUC977 RTC備份寄存器的使用

NUC970系列CPU和STM32一樣自帶RTC備份寄存器，供掉電前保存重要數據使用，容量是16x32bit=64byte

修改rtc驅動，增加nuc970_rtc_ioctl函數

struct nuc970_rtc_spr {
    unsigned int num;
    unsigned int value;
};

#define RTC_SPR_SET_DATA   0x0801
#define RTC_SPR_GET_DATA   0x0802

#define REG_RTC_SPR0    0x40 //RTC備份寄存器地址

static int nuc970_rtc_ioctl(struct device *dev, unsigned int cmd,
        unsigned long arg)
{
    struct nuc970_rtc *rtc = dev_get_drvdata(dev);
    struct nuc970_rtc_spr rtc_sprs;
    void __user *uarg = (void __user *) arg;
    int *err;
    unsigned char nums;

    err = check_rtc_spr_access_enable(rtc);

    if (IS_ERR(err))
    {
        return PTR_ERR(err);
    }

    if (copy_from_user(&rtc_sprs, uarg, sizeof(rtc_sprs)))
    {
        return -EFAULT;
    }
    nums = rtc_sprs.num;

    switch (cmd)
    {
        case RTC_SPR_SET_DATA:
            //printk("K: set rtc spr%d, value:%x\n", nums, rtc_sprs.value);
            rtc_reg_write(rtc, REG_RTC_SPR0+nums*4, rtc_sprs.value);
            break;
        case RTC_SPR_GET_DATA:
            rtc_sprs.value = rtc_reg_read(rtc, REG_RTC_SPR0+nums*4);
            //printk("K: get rtc spr%d, value:%x\n", nums, rtc_sprs.value);
            rtc_sprs.num = nums;

            if (copy_to_user(uarg, &rtc_sprs, sizeof(rtc_sprs)))
            {
                return -EFAULT;
            }

            break;
    }

    return 0;
}

static struct rtc_class_ops nuc970_rtc_ops = {
    .ioctl = nuc970_rtc_ioctl,
    .read_time = nuc970_rtc_read_time,
    .set_time = nuc970_rtc_set_time,
    .read_alarm = nuc970_rtc_read_alarm,
    .set_alarm = nuc970_rtc_set_alarm,
    .alarm_irq_enable = nuc970_alarm_irq_enable,
};

測試demo

#include <stdio.h>
#include <string.h>
#include <linux/rtc.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <math.h>
#include <signal.h>

struct nuc970_rtc_spr {
    unsigned int num;
    unsigned int value;
};

#define RTC_SPR_SET_DATA   0x0801
#define RTC_SPR_GET_DATA   0x0802

#define FILE_DEV "/dev/rtc0"
int main (int argc, char* argv[])
{
    int i=0;
    int fd = -1;
    int ret = -1;
    struct nuc970_rtc_spr rtc_spr;

    memset(&rtc_spr, 0x00, sizeof(rtc_spr));
    printf("---------------------\n");

    fd = open (FILE_DEV, O_RDWR);
    if (fd < 0)
    {
        printf("### open "FILE_DEV" fail!\n");
        return -1;
    }
    //測試讀RTC SPR0寄存器的值
    rtc_spr.num = 0;
    if ((ret = ioctl(fd, RTC_SPR_GET_DATA, &rtc_spr)) < 0)
    {
        printf("### ioctl "FILE_DEV" get rtc spr%d data faile %d\n", rtc_spr.num, ret);
        return ret;
    }

    printf("### read rtc spr%d data=0x%lx\n\n", rtc_spr.num, rtc_spr.value);
    //測試寫數據到RTC SPR0寄存器
    rtc_spr.num = 0;
    rtc_spr.value += 0xA5;
    printf("### write rtc spr%d data=0x%lx\n\n", rtc_spr.num, rtc_spr.value);
    if ((ret = ioctl(fd, RTC_SPR_SET_DATA, &rtc_spr)) < 0)
    {
        printf("### ioctl "FILE_DEV" set rtc spr%d data faile %d\n",rtc_spr.num, ret);
        return ret;
    }
    //測試讀RTC SPR1寄存器的值
    rtc_spr.num = 1;
    if ((ret = ioctl(fd, RTC_SPR_GET_DATA, &rtc_spr)) < 0)
    {
        printf("### ioctl "FILE_DEV" get rtc spr%d data faile %d\n", rtc_spr.num, ret);
        return ret;
    }
    printf("### read rtc spr%d data=0x%lx\n\n", rtc_spr.num, rtc_spr.value);

    //測試寫數據到RTC SPR1寄存器
    rtc_spr.num = 1;
    rtc_spr.value += 0xA6;
    printf("### write rtc spr%d data=0x%lx\n\n", rtc_spr.num, rtc_spr.value);
    if ((ret = ioctl(fd, RTC_SPR_SET_DATA, &rtc_spr)) < 0)
    {
        printf("### ioctl "FILE_DEV" set rtc spr%d data faile %d\n",rtc_spr.num, ret);
        return ret;
    }

    return 0;
}