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 size_t size_nvram; 57 unsigned long last_jiffies; 58 struct bin_attribute nvram_attr; 59 }; 60 61 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm) 62 { 63 struct platform_device *pdev = to_platform_device(dev); 64 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 65 void __iomem *ioaddr = pdata->ioaddr_rtc; 66 u8 century; 67 68 century = bin2bcd((tm->tm_year + 1900) / 100); 69 70 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 71 72 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR); 73 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH); 74 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY); 75 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE); 76 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS); 77 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES); 78 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS); 79 80 /* RTC_CENTURY and RTC_CONTROL share same register */ 81 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY); 82 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 83 return 0; 84 } 85 86 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm) 87 { 88 struct platform_device *pdev = to_platform_device(dev); 89 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 90 void __iomem *ioaddr = pdata->ioaddr_rtc; 91 unsigned int year, month, day, hour, minute, second, week; 92 unsigned int century; 93 94 /* give enough time to update RTC in case of continuous read */ 95 if (pdata->last_jiffies == jiffies) 96 msleep(1); 97 pdata->last_jiffies = jiffies; 98 writeb(RTC_READ, ioaddr + RTC_CONTROL); 99 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; 100 minute = readb(ioaddr + RTC_MINUTES); 101 hour = readb(ioaddr + RTC_HOURS); 102 day = readb(ioaddr + RTC_DATE); 103 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK; 104 month = readb(ioaddr + RTC_MONTH); 105 year = readb(ioaddr + RTC_YEAR); 106 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 107 writeb(0, ioaddr + RTC_CONTROL); 108 tm->tm_sec = bcd2bin(second); 109 tm->tm_min = bcd2bin(minute); 110 tm->tm_hour = bcd2bin(hour); 111 tm->tm_mday = bcd2bin(day); 112 tm->tm_wday = bcd2bin(week); 113 tm->tm_mon = bcd2bin(month) - 1; 114 /* year is 1900 + tm->tm_year */ 115 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; 116 117 return rtc_valid_tm(tm); 118 } 119 120 static const struct rtc_class_ops ds1742_rtc_ops = { 121 .read_time = ds1742_rtc_read_time, 122 .set_time = ds1742_rtc_set_time, 123 }; 124 125 static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj, 126 struct bin_attribute *bin_attr, 127 char *buf, loff_t pos, size_t size) 128 { 129 struct device *dev = container_of(kobj, struct device, kobj); 130 struct platform_device *pdev = to_platform_device(dev); 131 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 132 void __iomem *ioaddr = pdata->ioaddr_nvram; 133 ssize_t count; 134 135 for (count = 0; count < size; count++) 136 *buf++ = readb(ioaddr + pos++); 137 return count; 138 } 139 140 static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj, 141 struct bin_attribute *bin_attr, 142 char *buf, loff_t pos, size_t size) 143 { 144 struct device *dev = container_of(kobj, struct device, kobj); 145 struct platform_device *pdev = to_platform_device(dev); 146 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 147 void __iomem *ioaddr = pdata->ioaddr_nvram; 148 ssize_t count; 149 150 for (count = 0; count < size; count++) 151 writeb(*buf++, ioaddr + pos++); 152 return count; 153 } 154 155 static int ds1742_rtc_probe(struct platform_device *pdev) 156 { 157 struct rtc_device *rtc; 158 struct resource *res; 159 unsigned int cen, sec; 160 struct rtc_plat_data *pdata; 161 void __iomem *ioaddr; 162 int ret = 0; 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->size_nvram = resource_size(res) - RTC_SIZE; 175 pdata->ioaddr_rtc = ioaddr + pdata->size_nvram; 176 177 sysfs_bin_attr_init(&pdata->nvram_attr); 178 pdata->nvram_attr.attr.name = "nvram"; 179 pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR; 180 pdata->nvram_attr.read = ds1742_nvram_read; 181 pdata->nvram_attr.write = ds1742_nvram_write; 182 pdata->nvram_attr.size = pdata->size_nvram; 183 184 /* turn RTC on if it was not on */ 185 ioaddr = pdata->ioaddr_rtc; 186 sec = readb(ioaddr + RTC_SECONDS); 187 if (sec & RTC_STOP) { 188 sec &= RTC_SECONDS_MASK; 189 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 190 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 191 writeb(sec, ioaddr + RTC_SECONDS); 192 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 193 } 194 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG)) 195 dev_warn(&pdev->dev, "voltage-low detected.\n"); 196 197 pdata->last_jiffies = jiffies; 198 platform_set_drvdata(pdev, pdata); 199 rtc = devm_rtc_device_register(&pdev->dev, pdev->name, 200 &ds1742_rtc_ops, THIS_MODULE); 201 if (IS_ERR(rtc)) 202 return PTR_ERR(rtc); 203 204 ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr); 205 if (ret) 206 dev_err(&pdev->dev, "Unable to create sysfs entry: %s\n", 207 pdata->nvram_attr.attr.name); 208 209 return 0; 210 } 211 212 static int ds1742_rtc_remove(struct platform_device *pdev) 213 { 214 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 215 216 sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr); 217 return 0; 218 } 219 220 static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = { 221 { .compatible = "maxim,ds1742", }, 222 { } 223 }; 224 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match); 225 226 static struct platform_driver ds1742_rtc_driver = { 227 .probe = ds1742_rtc_probe, 228 .remove = ds1742_rtc_remove, 229 .driver = { 230 .name = "rtc-ds1742", 231 .of_match_table = of_match_ptr(ds1742_rtc_of_match), 232 }, 233 }; 234 235 module_platform_driver(ds1742_rtc_driver); 236 237 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); 238 MODULE_DESCRIPTION("Dallas DS1742 RTC driver"); 239 MODULE_LICENSE("GPL"); 240 MODULE_ALIAS("platform:rtc-ds1742"); 241