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/of_device.h> 20 #include <linux/platform_device.h> 21 #include <linux/io.h> 22 #include <linux/module.h> 23 24 #define RTC_SIZE 8 25 26 #define RTC_CONTROL 0 27 #define RTC_CENTURY 0 28 #define RTC_SECONDS 1 29 #define RTC_MINUTES 2 30 #define RTC_HOURS 3 31 #define RTC_DAY 4 32 #define RTC_DATE 5 33 #define RTC_MONTH 6 34 #define RTC_YEAR 7 35 36 #define RTC_CENTURY_MASK 0x3f 37 #define RTC_SECONDS_MASK 0x7f 38 #define RTC_DAY_MASK 0x07 39 40 /* Bits in the Control/Century register */ 41 #define RTC_WRITE 0x80 42 #define RTC_READ 0x40 43 44 /* Bits in the Seconds register */ 45 #define RTC_STOP 0x80 46 47 /* Bits in the Day register */ 48 #define RTC_BATT_FLAG 0x80 49 50 struct rtc_plat_data { 51 void __iomem *ioaddr_nvram; 52 void __iomem *ioaddr_rtc; 53 unsigned long last_jiffies; 54 }; 55 56 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm) 57 { 58 struct rtc_plat_data *pdata = dev_get_drvdata(dev); 59 void __iomem *ioaddr = pdata->ioaddr_rtc; 60 u8 century; 61 62 century = bin2bcd((tm->tm_year + 1900) / 100); 63 64 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 65 66 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR); 67 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH); 68 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY); 69 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE); 70 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS); 71 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES); 72 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS); 73 74 /* RTC_CENTURY and RTC_CONTROL share same register */ 75 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY); 76 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 77 return 0; 78 } 79 80 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm) 81 { 82 struct rtc_plat_data *pdata = dev_get_drvdata(dev); 83 void __iomem *ioaddr = pdata->ioaddr_rtc; 84 unsigned int year, month, day, hour, minute, second, week; 85 unsigned int century; 86 87 /* give enough time to update RTC in case of continuous read */ 88 if (pdata->last_jiffies == jiffies) 89 msleep(1); 90 pdata->last_jiffies = jiffies; 91 writeb(RTC_READ, ioaddr + RTC_CONTROL); 92 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; 93 minute = readb(ioaddr + RTC_MINUTES); 94 hour = readb(ioaddr + RTC_HOURS); 95 day = readb(ioaddr + RTC_DATE); 96 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK; 97 month = readb(ioaddr + RTC_MONTH); 98 year = readb(ioaddr + RTC_YEAR); 99 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 100 writeb(0, ioaddr + RTC_CONTROL); 101 tm->tm_sec = bcd2bin(second); 102 tm->tm_min = bcd2bin(minute); 103 tm->tm_hour = bcd2bin(hour); 104 tm->tm_mday = bcd2bin(day); 105 tm->tm_wday = bcd2bin(week); 106 tm->tm_mon = bcd2bin(month) - 1; 107 /* year is 1900 + tm->tm_year */ 108 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; 109 110 return 0; 111 } 112 113 static const struct rtc_class_ops ds1742_rtc_ops = { 114 .read_time = ds1742_rtc_read_time, 115 .set_time = ds1742_rtc_set_time, 116 }; 117 118 static int ds1742_nvram_read(void *priv, unsigned int pos, void *val, 119 size_t bytes) 120 { 121 struct rtc_plat_data *pdata = priv; 122 void __iomem *ioaddr = pdata->ioaddr_nvram; 123 u8 *buf = val; 124 125 for (; bytes; bytes--) 126 *buf++ = readb(ioaddr + pos++); 127 return 0; 128 } 129 130 static int ds1742_nvram_write(void *priv, unsigned int pos, void *val, 131 size_t bytes) 132 { 133 struct rtc_plat_data *pdata = priv; 134 void __iomem *ioaddr = pdata->ioaddr_nvram; 135 u8 *buf = val; 136 137 for (; bytes; bytes--) 138 writeb(*buf++, ioaddr + pos++); 139 return 0; 140 } 141 142 static int ds1742_rtc_probe(struct platform_device *pdev) 143 { 144 struct rtc_device *rtc; 145 struct resource *res; 146 unsigned int cen, sec; 147 struct rtc_plat_data *pdata; 148 void __iomem *ioaddr; 149 int ret = 0; 150 struct nvmem_config nvmem_cfg = { 151 .name = "ds1742_nvram", 152 .reg_read = ds1742_nvram_read, 153 .reg_write = ds1742_nvram_write, 154 }; 155 156 157 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 158 if (!pdata) 159 return -ENOMEM; 160 161 ioaddr = devm_platform_get_and_ioremap_resource(pdev, 0, &res); 162 if (IS_ERR(ioaddr)) 163 return PTR_ERR(ioaddr); 164 165 pdata->ioaddr_nvram = ioaddr; 166 pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE; 167 168 nvmem_cfg.size = resource_size(res) - RTC_SIZE; 169 nvmem_cfg.priv = pdata; 170 171 /* turn RTC on if it was not on */ 172 ioaddr = pdata->ioaddr_rtc; 173 sec = readb(ioaddr + RTC_SECONDS); 174 if (sec & RTC_STOP) { 175 sec &= RTC_SECONDS_MASK; 176 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 177 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 178 writeb(sec, ioaddr + RTC_SECONDS); 179 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 180 } 181 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG)) 182 dev_warn(&pdev->dev, "voltage-low detected.\n"); 183 184 pdata->last_jiffies = jiffies; 185 platform_set_drvdata(pdev, pdata); 186 187 rtc = devm_rtc_allocate_device(&pdev->dev); 188 if (IS_ERR(rtc)) 189 return PTR_ERR(rtc); 190 191 rtc->ops = &ds1742_rtc_ops; 192 193 ret = devm_rtc_register_device(rtc); 194 if (ret) 195 return ret; 196 197 devm_rtc_nvmem_register(rtc, &nvmem_cfg); 198 199 return 0; 200 } 201 202 static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = { 203 { .compatible = "maxim,ds1742", }, 204 { } 205 }; 206 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match); 207 208 static struct platform_driver ds1742_rtc_driver = { 209 .probe = ds1742_rtc_probe, 210 .driver = { 211 .name = "rtc-ds1742", 212 .of_match_table = of_match_ptr(ds1742_rtc_of_match), 213 }, 214 }; 215 216 module_platform_driver(ds1742_rtc_driver); 217 218 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); 219 MODULE_DESCRIPTION("Dallas DS1742 RTC driver"); 220 MODULE_LICENSE("GPL"); 221 MODULE_ALIAS("platform:rtc-ds1742"); 222