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 platform_device *pdev = to_platform_device(dev); 62 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 63 void __iomem *ioaddr = pdata->ioaddr_rtc; 64 u8 century; 65 66 century = bin2bcd((tm->tm_year + 1900) / 100); 67 68 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 69 70 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR); 71 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH); 72 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY); 73 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE); 74 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS); 75 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES); 76 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS); 77 78 /* RTC_CENTURY and RTC_CONTROL share same register */ 79 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY); 80 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 81 return 0; 82 } 83 84 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm) 85 { 86 struct platform_device *pdev = to_platform_device(dev); 87 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 88 void __iomem *ioaddr = pdata->ioaddr_rtc; 89 unsigned int year, month, day, hour, minute, second, week; 90 unsigned int century; 91 92 /* give enough time to update RTC in case of continuous read */ 93 if (pdata->last_jiffies == jiffies) 94 msleep(1); 95 pdata->last_jiffies = jiffies; 96 writeb(RTC_READ, ioaddr + RTC_CONTROL); 97 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; 98 minute = readb(ioaddr + RTC_MINUTES); 99 hour = readb(ioaddr + RTC_HOURS); 100 day = readb(ioaddr + RTC_DATE); 101 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK; 102 month = readb(ioaddr + RTC_MONTH); 103 year = readb(ioaddr + RTC_YEAR); 104 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 105 writeb(0, ioaddr + RTC_CONTROL); 106 tm->tm_sec = bcd2bin(second); 107 tm->tm_min = bcd2bin(minute); 108 tm->tm_hour = bcd2bin(hour); 109 tm->tm_mday = bcd2bin(day); 110 tm->tm_wday = bcd2bin(week); 111 tm->tm_mon = bcd2bin(month) - 1; 112 /* year is 1900 + tm->tm_year */ 113 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; 114 115 return 0; 116 } 117 118 static const struct rtc_class_ops ds1742_rtc_ops = { 119 .read_time = ds1742_rtc_read_time, 120 .set_time = ds1742_rtc_set_time, 121 }; 122 123 static int ds1742_nvram_read(void *priv, unsigned int pos, void *val, 124 size_t bytes) 125 { 126 struct rtc_plat_data *pdata = priv; 127 void __iomem *ioaddr = pdata->ioaddr_nvram; 128 u8 *buf = val; 129 130 for (; bytes; bytes--) 131 *buf++ = readb(ioaddr + pos++); 132 return 0; 133 } 134 135 static int ds1742_nvram_write(void *priv, unsigned int pos, void *val, 136 size_t bytes) 137 { 138 struct rtc_plat_data *pdata = priv; 139 void __iomem *ioaddr = pdata->ioaddr_nvram; 140 u8 *buf = val; 141 142 for (; bytes; bytes--) 143 writeb(*buf++, ioaddr + pos++); 144 return 0; 145 } 146 147 static int ds1742_rtc_probe(struct platform_device *pdev) 148 { 149 struct rtc_device *rtc; 150 struct resource *res; 151 unsigned int cen, sec; 152 struct rtc_plat_data *pdata; 153 void __iomem *ioaddr; 154 int ret = 0; 155 struct nvmem_config nvmem_cfg = { 156 .name = "ds1742_nvram", 157 .word_size = 1, 158 .stride = 1, 159 .reg_read = ds1742_nvram_read, 160 .reg_write = ds1742_nvram_write, 161 }; 162 163 164 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 165 if (!pdata) 166 return -ENOMEM; 167 168 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 169 ioaddr = devm_ioremap_resource(&pdev->dev, res); 170 if (IS_ERR(ioaddr)) 171 return PTR_ERR(ioaddr); 172 173 pdata->ioaddr_nvram = ioaddr; 174 pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE; 175 176 nvmem_cfg.size = resource_size(res) - RTC_SIZE; 177 nvmem_cfg.priv = pdata; 178 179 /* turn RTC on if it was not on */ 180 ioaddr = pdata->ioaddr_rtc; 181 sec = readb(ioaddr + RTC_SECONDS); 182 if (sec & RTC_STOP) { 183 sec &= RTC_SECONDS_MASK; 184 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 185 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 186 writeb(sec, ioaddr + RTC_SECONDS); 187 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 188 } 189 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG)) 190 dev_warn(&pdev->dev, "voltage-low detected.\n"); 191 192 pdata->last_jiffies = jiffies; 193 platform_set_drvdata(pdev, pdata); 194 195 rtc = devm_rtc_allocate_device(&pdev->dev); 196 if (IS_ERR(rtc)) 197 return PTR_ERR(rtc); 198 199 rtc->ops = &ds1742_rtc_ops; 200 rtc->nvram_old_abi = true; 201 202 ret = rtc_register_device(rtc); 203 if (ret) 204 return ret; 205 206 if (rtc_nvmem_register(rtc, &nvmem_cfg)) 207 dev_err(&pdev->dev, "Unable to register nvmem\n"); 208 209 return 0; 210 } 211 212 static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = { 213 { .compatible = "maxim,ds1742", }, 214 { } 215 }; 216 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match); 217 218 static struct platform_driver ds1742_rtc_driver = { 219 .probe = ds1742_rtc_probe, 220 .driver = { 221 .name = "rtc-ds1742", 222 .of_match_table = of_match_ptr(ds1742_rtc_of_match), 223 }, 224 }; 225 226 module_platform_driver(ds1742_rtc_driver); 227 228 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); 229 MODULE_DESCRIPTION("Dallas DS1742 RTC driver"); 230 MODULE_LICENSE("GPL"); 231 MODULE_ALIAS("platform:rtc-ds1742"); 232