1 /* 2 * An rtc driver for the Dallas DS1742 3 * 4 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk> 11 * - nvram size determined from resource 12 * - this ds1742 driver now supports ds1743. 13 */ 14 15 #include <linux/bcd.h> 16 #include <linux/kernel.h> 17 #include <linux/gfp.h> 18 #include <linux/delay.h> 19 #include <linux/jiffies.h> 20 #include <linux/rtc.h> 21 #include <linux/of.h> 22 #include <linux/of_device.h> 23 #include <linux/platform_device.h> 24 #include <linux/io.h> 25 #include <linux/module.h> 26 27 #define RTC_SIZE 8 28 29 #define RTC_CONTROL 0 30 #define RTC_CENTURY 0 31 #define RTC_SECONDS 1 32 #define RTC_MINUTES 2 33 #define RTC_HOURS 3 34 #define RTC_DAY 4 35 #define RTC_DATE 5 36 #define RTC_MONTH 6 37 #define RTC_YEAR 7 38 39 #define RTC_CENTURY_MASK 0x3f 40 #define RTC_SECONDS_MASK 0x7f 41 #define RTC_DAY_MASK 0x07 42 43 /* Bits in the Control/Century register */ 44 #define RTC_WRITE 0x80 45 #define RTC_READ 0x40 46 47 /* Bits in the Seconds register */ 48 #define RTC_STOP 0x80 49 50 /* Bits in the Day register */ 51 #define RTC_BATT_FLAG 0x80 52 53 struct rtc_plat_data { 54 void __iomem *ioaddr_nvram; 55 void __iomem *ioaddr_rtc; 56 unsigned long last_jiffies; 57 }; 58 59 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm) 60 { 61 struct rtc_plat_data *pdata = dev_get_drvdata(dev); 62 void __iomem *ioaddr = pdata->ioaddr_rtc; 63 u8 century; 64 65 century = bin2bcd((tm->tm_year + 1900) / 100); 66 67 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 68 69 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR); 70 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH); 71 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY); 72 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE); 73 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS); 74 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES); 75 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS); 76 77 /* RTC_CENTURY and RTC_CONTROL share same register */ 78 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY); 79 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 80 return 0; 81 } 82 83 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm) 84 { 85 struct rtc_plat_data *pdata = dev_get_drvdata(dev); 86 void __iomem *ioaddr = pdata->ioaddr_rtc; 87 unsigned int year, month, day, hour, minute, second, week; 88 unsigned int century; 89 90 /* give enough time to update RTC in case of continuous read */ 91 if (pdata->last_jiffies == jiffies) 92 msleep(1); 93 pdata->last_jiffies = jiffies; 94 writeb(RTC_READ, ioaddr + RTC_CONTROL); 95 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; 96 minute = readb(ioaddr + RTC_MINUTES); 97 hour = readb(ioaddr + RTC_HOURS); 98 day = readb(ioaddr + RTC_DATE); 99 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK; 100 month = readb(ioaddr + RTC_MONTH); 101 year = readb(ioaddr + RTC_YEAR); 102 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 103 writeb(0, ioaddr + RTC_CONTROL); 104 tm->tm_sec = bcd2bin(second); 105 tm->tm_min = bcd2bin(minute); 106 tm->tm_hour = bcd2bin(hour); 107 tm->tm_mday = bcd2bin(day); 108 tm->tm_wday = bcd2bin(week); 109 tm->tm_mon = bcd2bin(month) - 1; 110 /* year is 1900 + tm->tm_year */ 111 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; 112 113 return 0; 114 } 115 116 static const struct rtc_class_ops ds1742_rtc_ops = { 117 .read_time = ds1742_rtc_read_time, 118 .set_time = ds1742_rtc_set_time, 119 }; 120 121 static int ds1742_nvram_read(void *priv, unsigned int pos, void *val, 122 size_t bytes) 123 { 124 struct rtc_plat_data *pdata = priv; 125 void __iomem *ioaddr = pdata->ioaddr_nvram; 126 u8 *buf = val; 127 128 for (; bytes; bytes--) 129 *buf++ = readb(ioaddr + pos++); 130 return 0; 131 } 132 133 static int ds1742_nvram_write(void *priv, unsigned int pos, void *val, 134 size_t bytes) 135 { 136 struct rtc_plat_data *pdata = priv; 137 void __iomem *ioaddr = pdata->ioaddr_nvram; 138 u8 *buf = val; 139 140 for (; bytes; bytes--) 141 writeb(*buf++, ioaddr + pos++); 142 return 0; 143 } 144 145 static int ds1742_rtc_probe(struct platform_device *pdev) 146 { 147 struct rtc_device *rtc; 148 struct resource *res; 149 unsigned int cen, sec; 150 struct rtc_plat_data *pdata; 151 void __iomem *ioaddr; 152 int ret = 0; 153 struct nvmem_config nvmem_cfg = { 154 .name = "ds1742_nvram", 155 .reg_read = ds1742_nvram_read, 156 .reg_write = ds1742_nvram_write, 157 }; 158 159 160 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 161 if (!pdata) 162 return -ENOMEM; 163 164 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 165 ioaddr = devm_ioremap_resource(&pdev->dev, res); 166 if (IS_ERR(ioaddr)) 167 return PTR_ERR(ioaddr); 168 169 pdata->ioaddr_nvram = ioaddr; 170 pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE; 171 172 nvmem_cfg.size = resource_size(res) - RTC_SIZE; 173 nvmem_cfg.priv = pdata; 174 175 /* turn RTC on if it was not on */ 176 ioaddr = pdata->ioaddr_rtc; 177 sec = readb(ioaddr + RTC_SECONDS); 178 if (sec & RTC_STOP) { 179 sec &= RTC_SECONDS_MASK; 180 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 181 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 182 writeb(sec, ioaddr + RTC_SECONDS); 183 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 184 } 185 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG)) 186 dev_warn(&pdev->dev, "voltage-low detected.\n"); 187 188 pdata->last_jiffies = jiffies; 189 platform_set_drvdata(pdev, pdata); 190 191 rtc = devm_rtc_allocate_device(&pdev->dev); 192 if (IS_ERR(rtc)) 193 return PTR_ERR(rtc); 194 195 rtc->ops = &ds1742_rtc_ops; 196 rtc->nvram_old_abi = true; 197 198 ret = rtc_register_device(rtc); 199 if (ret) 200 return ret; 201 202 if (rtc_nvmem_register(rtc, &nvmem_cfg)) 203 dev_err(&pdev->dev, "Unable to register nvmem\n"); 204 205 return 0; 206 } 207 208 static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = { 209 { .compatible = "maxim,ds1742", }, 210 { } 211 }; 212 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match); 213 214 static struct platform_driver ds1742_rtc_driver = { 215 .probe = ds1742_rtc_probe, 216 .driver = { 217 .name = "rtc-ds1742", 218 .of_match_table = of_match_ptr(ds1742_rtc_of_match), 219 }, 220 }; 221 222 module_platform_driver(ds1742_rtc_driver); 223 224 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); 225 MODULE_DESCRIPTION("Dallas DS1742 RTC driver"); 226 MODULE_LICENSE("GPL"); 227 MODULE_ALIAS("platform:rtc-ds1742"); 228