1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * An rtc driver for the Dallas DS1742 4 * 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 resource 9 * - 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 8 24 25 #define RTC_CONTROL 0 26 #define RTC_CENTURY 0 27 #define RTC_SECONDS 1 28 #define RTC_MINUTES 2 29 #define RTC_HOURS 3 30 #define RTC_DAY 4 31 #define RTC_DATE 5 32 #define RTC_MONTH 6 33 #define RTC_YEAR 7 34 35 #define RTC_CENTURY_MASK 0x3f 36 #define RTC_SECONDS_MASK 0x7f 37 #define RTC_DAY_MASK 0x07 38 39 /* Bits in the Control/Century register */ 40 #define RTC_WRITE 0x80 41 #define RTC_READ 0x40 42 43 /* Bits in the Seconds register */ 44 #define RTC_STOP 0x80 45 46 /* Bits in the Day register */ 47 #define RTC_BATT_FLAG 0x80 48 49 struct rtc_plat_data { 50 void __iomem *ioaddr_nvram; 51 void __iomem *ioaddr_rtc; 52 unsigned long last_jiffies; 53 }; 54 55 static 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 79 static 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 } 111 112 static const struct rtc_class_ops ds1742_rtc_ops = { 113 .read_time = ds1742_rtc_read_time, 114 .set_time = ds1742_rtc_set_time, 115 }; 116 117 static 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 } 128 129 static 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 } 140 141 static 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 } 200 201 static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = { 202 { .compatible = "maxim,ds1742", }, 203 { } 204 }; 205 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match); 206 207 static 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 }; 214 215 module_platform_driver(ds1742_rtc_driver); 216 217 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); 218 MODULE_DESCRIPTION("Dallas DS1742 RTC driver"); 219 MODULE_LICENSE("GPL"); 220 MODULE_ALIAS("platform:rtc-ds1742"); 221