245 lines
7.1 KiB
C
245 lines
7.1 KiB
C
/*
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* An rtc driver for the Dallas DS1742
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*
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* Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk>
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* - nvram size determined from resource
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* - this ds1742 driver now supports ds1743.
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*/
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#include <linux/bcd.h>
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#include <linux/kernel.h>
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#include <linux/gfp.h>
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#include <linux/delay.h>
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#include <linux/jiffies.h>
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#include <linux/rtc.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#define DRV_VERSION "0.4"
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#define RTC_SIZE 8
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#define RTC_CONTROL 0
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#define RTC_CENTURY 0
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#define RTC_SECONDS 1
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#define RTC_MINUTES 2
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#define RTC_HOURS 3
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#define RTC_DAY 4
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#define RTC_DATE 5
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#define RTC_MONTH 6
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#define RTC_YEAR 7
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#define RTC_CENTURY_MASK 0x3f
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#define RTC_SECONDS_MASK 0x7f
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#define RTC_DAY_MASK 0x07
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/* Bits in the Control/Century register */
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#define RTC_WRITE 0x80
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#define RTC_READ 0x40
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/* Bits in the Seconds register */
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#define RTC_STOP 0x80
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/* Bits in the Day register */
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#define RTC_BATT_FLAG 0x80
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struct rtc_plat_data {
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void __iomem *ioaddr_nvram;
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void __iomem *ioaddr_rtc;
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size_t size_nvram;
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unsigned long last_jiffies;
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struct bin_attribute nvram_attr;
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};
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static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct platform_device *pdev = to_platform_device(dev);
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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void __iomem *ioaddr = pdata->ioaddr_rtc;
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u8 century;
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century = bin2bcd((tm->tm_year + 1900) / 100);
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writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
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writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
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writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
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writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
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writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
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writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
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writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
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writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
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/* RTC_CENTURY and RTC_CONTROL share same register */
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writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
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writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
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return 0;
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}
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static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct platform_device *pdev = to_platform_device(dev);
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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void __iomem *ioaddr = pdata->ioaddr_rtc;
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unsigned int year, month, day, hour, minute, second, week;
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unsigned int century;
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/* give enough time to update RTC in case of continuous read */
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if (pdata->last_jiffies == jiffies)
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msleep(1);
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pdata->last_jiffies = jiffies;
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writeb(RTC_READ, ioaddr + RTC_CONTROL);
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second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
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minute = readb(ioaddr + RTC_MINUTES);
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hour = readb(ioaddr + RTC_HOURS);
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day = readb(ioaddr + RTC_DATE);
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week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
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month = readb(ioaddr + RTC_MONTH);
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year = readb(ioaddr + RTC_YEAR);
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century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
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writeb(0, ioaddr + RTC_CONTROL);
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tm->tm_sec = bcd2bin(second);
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tm->tm_min = bcd2bin(minute);
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tm->tm_hour = bcd2bin(hour);
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tm->tm_mday = bcd2bin(day);
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tm->tm_wday = bcd2bin(week);
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tm->tm_mon = bcd2bin(month) - 1;
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/* year is 1900 + tm->tm_year */
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tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
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return rtc_valid_tm(tm);
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}
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static const struct rtc_class_ops ds1742_rtc_ops = {
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.read_time = ds1742_rtc_read_time,
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.set_time = ds1742_rtc_set_time,
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};
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static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t pos, size_t size)
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{
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struct device *dev = container_of(kobj, struct device, kobj);
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struct platform_device *pdev = to_platform_device(dev);
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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void __iomem *ioaddr = pdata->ioaddr_nvram;
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ssize_t count;
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for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
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*buf++ = readb(ioaddr + pos++);
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return count;
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}
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static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t pos, size_t size)
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{
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struct device *dev = container_of(kobj, struct device, kobj);
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struct platform_device *pdev = to_platform_device(dev);
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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void __iomem *ioaddr = pdata->ioaddr_nvram;
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ssize_t count;
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for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
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writeb(*buf++, ioaddr + pos++);
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return count;
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}
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static int ds1742_rtc_probe(struct platform_device *pdev)
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{
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struct rtc_device *rtc;
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struct resource *res;
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unsigned int cen, sec;
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struct rtc_plat_data *pdata;
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void __iomem *ioaddr;
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int ret = 0;
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pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
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if (!pdata)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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ioaddr = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(ioaddr))
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return PTR_ERR(ioaddr);
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pdata->ioaddr_nvram = ioaddr;
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pdata->size_nvram = resource_size(res) - RTC_SIZE;
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pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
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sysfs_bin_attr_init(&pdata->nvram_attr);
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pdata->nvram_attr.attr.name = "nvram";
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pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
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pdata->nvram_attr.read = ds1742_nvram_read;
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pdata->nvram_attr.write = ds1742_nvram_write;
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pdata->nvram_attr.size = pdata->size_nvram;
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/* turn RTC on if it was not on */
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ioaddr = pdata->ioaddr_rtc;
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sec = readb(ioaddr + RTC_SECONDS);
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if (sec & RTC_STOP) {
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sec &= RTC_SECONDS_MASK;
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cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
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writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
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writeb(sec, ioaddr + RTC_SECONDS);
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writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
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}
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if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
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dev_warn(&pdev->dev, "voltage-low detected.\n");
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pdata->last_jiffies = jiffies;
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platform_set_drvdata(pdev, pdata);
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rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
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&ds1742_rtc_ops, THIS_MODULE);
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if (IS_ERR(rtc))
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return PTR_ERR(rtc);
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ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
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if (ret)
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dev_err(&pdev->dev, "Unable to create sysfs entry: %s\n",
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pdata->nvram_attr.attr.name);
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return 0;
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}
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static int ds1742_rtc_remove(struct platform_device *pdev)
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{
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
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return 0;
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}
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static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
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{ .compatible = "maxim,ds1742", },
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{ }
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};
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MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
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static struct platform_driver ds1742_rtc_driver = {
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.probe = ds1742_rtc_probe,
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.remove = ds1742_rtc_remove,
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.driver = {
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.name = "rtc-ds1742",
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.owner = THIS_MODULE,
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.of_match_table = of_match_ptr(ds1742_rtc_of_match),
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},
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};
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module_platform_driver(ds1742_rtc_driver);
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MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
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MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
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MODULE_LICENSE("GPL");
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MODULE_VERSION(DRV_VERSION);
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MODULE_ALIAS("platform:rtc-ds1742");
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