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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * An rtc driver for the Dallas DS17424 *5 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>6 *7 * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk>8 * - nvram size determined from resource9 * - this ds1742 driver now supports ds1743.10 */11 12#include <linux/bcd.h>13#include <linux/kernel.h>14#include <linux/gfp.h>15#include <linux/delay.h>16#include <linux/jiffies.h>17#include <linux/rtc.h>18#include <linux/of.h>19#include <linux/platform_device.h>20#include <linux/io.h>21#include <linux/module.h>22 23#define RTC_SIZE 824 25#define RTC_CONTROL 026#define RTC_CENTURY 027#define RTC_SECONDS 128#define RTC_MINUTES 229#define RTC_HOURS 330#define RTC_DAY 431#define RTC_DATE 532#define RTC_MONTH 633#define RTC_YEAR 734 35#define RTC_CENTURY_MASK 0x3f36#define RTC_SECONDS_MASK 0x7f37#define RTC_DAY_MASK 0x0738 39/* Bits in the Control/Century register */40#define RTC_WRITE 0x8041#define RTC_READ 0x4042 43/* Bits in the Seconds register */44#define RTC_STOP 0x8045 46/* Bits in the Day register */47#define RTC_BATT_FLAG 0x8048 49struct rtc_plat_data {50 void __iomem *ioaddr_nvram;51 void __iomem *ioaddr_rtc;52 unsigned long last_jiffies;53};54 55static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)56{57 struct rtc_plat_data *pdata = dev_get_drvdata(dev);58 void __iomem *ioaddr = pdata->ioaddr_rtc;59 u8 century;60 61 century = bin2bcd((tm->tm_year + 1900) / 100);62 63 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);64 65 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);66 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);67 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);68 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);69 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);70 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);71 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);72 73 /* RTC_CENTURY and RTC_CONTROL share same register */74 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);75 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);76 return 0;77}78 79static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)80{81 struct rtc_plat_data *pdata = dev_get_drvdata(dev);82 void __iomem *ioaddr = pdata->ioaddr_rtc;83 unsigned int year, month, day, hour, minute, second, week;84 unsigned int century;85 86 /* give enough time to update RTC in case of continuous read */87 if (pdata->last_jiffies == jiffies)88 msleep(1);89 pdata->last_jiffies = jiffies;90 writeb(RTC_READ, ioaddr + RTC_CONTROL);91 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;92 minute = readb(ioaddr + RTC_MINUTES);93 hour = readb(ioaddr + RTC_HOURS);94 day = readb(ioaddr + RTC_DATE);95 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;96 month = readb(ioaddr + RTC_MONTH);97 year = readb(ioaddr + RTC_YEAR);98 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;99 writeb(0, ioaddr + RTC_CONTROL);100 tm->tm_sec = bcd2bin(second);101 tm->tm_min = bcd2bin(minute);102 tm->tm_hour = bcd2bin(hour);103 tm->tm_mday = bcd2bin(day);104 tm->tm_wday = bcd2bin(week);105 tm->tm_mon = bcd2bin(month) - 1;106 /* year is 1900 + tm->tm_year */107 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;108 109 return 0;110}111 112static const struct rtc_class_ops ds1742_rtc_ops = {113 .read_time = ds1742_rtc_read_time,114 .set_time = ds1742_rtc_set_time,115};116 117static int ds1742_nvram_read(void *priv, unsigned int pos, void *val,118 size_t bytes)119{120 struct rtc_plat_data *pdata = priv;121 void __iomem *ioaddr = pdata->ioaddr_nvram;122 u8 *buf = val;123 124 for (; bytes; bytes--)125 *buf++ = readb(ioaddr + pos++);126 return 0;127}128 129static int ds1742_nvram_write(void *priv, unsigned int pos, void *val,130 size_t bytes)131{132 struct rtc_plat_data *pdata = priv;133 void __iomem *ioaddr = pdata->ioaddr_nvram;134 u8 *buf = val;135 136 for (; bytes; bytes--)137 writeb(*buf++, ioaddr + pos++);138 return 0;139}140 141static int ds1742_rtc_probe(struct platform_device *pdev)142{143 struct rtc_device *rtc;144 struct resource *res;145 unsigned int cen, sec;146 struct rtc_plat_data *pdata;147 void __iomem *ioaddr;148 int ret = 0;149 struct nvmem_config nvmem_cfg = {150 .name = "ds1742_nvram",151 .reg_read = ds1742_nvram_read,152 .reg_write = ds1742_nvram_write,153 };154 155 156 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);157 if (!pdata)158 return -ENOMEM;159 160 ioaddr = devm_platform_get_and_ioremap_resource(pdev, 0, &res);161 if (IS_ERR(ioaddr))162 return PTR_ERR(ioaddr);163 164 pdata->ioaddr_nvram = ioaddr;165 pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE;166 167 nvmem_cfg.size = resource_size(res) - RTC_SIZE;168 nvmem_cfg.priv = pdata;169 170 /* turn RTC on if it was not on */171 ioaddr = pdata->ioaddr_rtc;172 sec = readb(ioaddr + RTC_SECONDS);173 if (sec & RTC_STOP) {174 sec &= RTC_SECONDS_MASK;175 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;176 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);177 writeb(sec, ioaddr + RTC_SECONDS);178 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);179 }180 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))181 dev_warn(&pdev->dev, "voltage-low detected.\n");182 183 pdata->last_jiffies = jiffies;184 platform_set_drvdata(pdev, pdata);185 186 rtc = devm_rtc_allocate_device(&pdev->dev);187 if (IS_ERR(rtc))188 return PTR_ERR(rtc);189 190 rtc->ops = &ds1742_rtc_ops;191 192 ret = devm_rtc_register_device(rtc);193 if (ret)194 return ret;195 196 devm_rtc_nvmem_register(rtc, &nvmem_cfg);197 198 return 0;199}200 201static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {202 { .compatible = "maxim,ds1742", },203 { }204};205MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);206 207static struct platform_driver ds1742_rtc_driver = {208 .probe = ds1742_rtc_probe,209 .driver = {210 .name = "rtc-ds1742",211 .of_match_table = of_match_ptr(ds1742_rtc_of_match),212 },213};214 215module_platform_driver(ds1742_rtc_driver);216 217MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");218MODULE_DESCRIPTION("Dallas DS1742 RTC driver");219MODULE_LICENSE("GPL");220MODULE_ALIAS("platform:rtc-ds1742");221