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 DRV_VERSION "0.4" 28 29 #define RTC_SIZE 8 30 31 #define RTC_CONTROL 0 32 #define RTC_CENTURY 0 33 #define RTC_SECONDS 1 34 #define RTC_MINUTES 2 35 #define RTC_HOURS 3 36 #define RTC_DAY 4 37 #define RTC_DATE 5 38 #define RTC_MONTH 6 39 #define RTC_YEAR 7 40 41 #define RTC_CENTURY_MASK 0x3f 42 #define RTC_SECONDS_MASK 0x7f 43 #define RTC_DAY_MASK 0x07 44 45 /* Bits in the Control/Century register */ 46 #define RTC_WRITE 0x80 47 #define RTC_READ 0x40 48 49 /* Bits in the Seconds register */ 50 #define RTC_STOP 0x80 51 52 /* Bits in the Day register */ 53 #define RTC_BATT_FLAG 0x80 54 55 struct rtc_plat_data { 56 void __iomem *ioaddr_nvram; 57 void __iomem *ioaddr_rtc; 58 size_t size_nvram; 59 unsigned long last_jiffies; 60 struct bin_attribute nvram_attr; 61 }; 62 63 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm) 64 { 65 struct platform_device *pdev = to_platform_device(dev); 66 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 67 void __iomem *ioaddr = pdata->ioaddr_rtc; 68 u8 century; 69 70 century = bin2bcd((tm->tm_year + 1900) / 100); 71 72 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 73 74 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR); 75 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH); 76 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY); 77 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE); 78 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS); 79 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES); 80 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS); 81 82 /* RTC_CENTURY and RTC_CONTROL share same register */ 83 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY); 84 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 85 return 0; 86 } 87 88 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm) 89 { 90 struct platform_device *pdev = to_platform_device(dev); 91 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 92 void __iomem *ioaddr = pdata->ioaddr_rtc; 93 unsigned int year, month, day, hour, minute, second, week; 94 unsigned int century; 95 96 /* give enough time to update RTC in case of continuous read */ 97 if (pdata->last_jiffies == jiffies) 98 msleep(1); 99 pdata->last_jiffies = jiffies; 100 writeb(RTC_READ, ioaddr + RTC_CONTROL); 101 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; 102 minute = readb(ioaddr + RTC_MINUTES); 103 hour = readb(ioaddr + RTC_HOURS); 104 day = readb(ioaddr + RTC_DATE); 105 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK; 106 month = readb(ioaddr + RTC_MONTH); 107 year = readb(ioaddr + RTC_YEAR); 108 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 109 writeb(0, ioaddr + RTC_CONTROL); 110 tm->tm_sec = bcd2bin(second); 111 tm->tm_min = bcd2bin(minute); 112 tm->tm_hour = bcd2bin(hour); 113 tm->tm_mday = bcd2bin(day); 114 tm->tm_wday = bcd2bin(week); 115 tm->tm_mon = bcd2bin(month) - 1; 116 /* year is 1900 + tm->tm_year */ 117 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; 118 119 return rtc_valid_tm(tm); 120 } 121 122 static const struct rtc_class_ops ds1742_rtc_ops = { 123 .read_time = ds1742_rtc_read_time, 124 .set_time = ds1742_rtc_set_time, 125 }; 126 127 static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj, 128 struct bin_attribute *bin_attr, 129 char *buf, loff_t pos, size_t size) 130 { 131 struct device *dev = container_of(kobj, struct device, kobj); 132 struct platform_device *pdev = to_platform_device(dev); 133 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 134 void __iomem *ioaddr = pdata->ioaddr_nvram; 135 ssize_t count; 136 137 for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--) 138 *buf++ = readb(ioaddr + pos++); 139 return count; 140 } 141 142 static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj, 143 struct bin_attribute *bin_attr, 144 char *buf, loff_t pos, size_t size) 145 { 146 struct device *dev = container_of(kobj, struct device, kobj); 147 struct platform_device *pdev = to_platform_device(dev); 148 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 149 void __iomem *ioaddr = pdata->ioaddr_nvram; 150 ssize_t count; 151 152 for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--) 153 writeb(*buf++, ioaddr + pos++); 154 return count; 155 } 156 157 static int ds1742_rtc_probe(struct platform_device *pdev) 158 { 159 struct rtc_device *rtc; 160 struct resource *res; 161 unsigned int cen, sec; 162 struct rtc_plat_data *pdata; 163 void __iomem *ioaddr; 164 int ret = 0; 165 166 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 167 if (!pdata) 168 return -ENOMEM; 169 170 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 171 ioaddr = devm_ioremap_resource(&pdev->dev, res); 172 if (IS_ERR(ioaddr)) 173 return PTR_ERR(ioaddr); 174 175 pdata->ioaddr_nvram = ioaddr; 176 pdata->size_nvram = resource_size(res) - RTC_SIZE; 177 pdata->ioaddr_rtc = ioaddr + pdata->size_nvram; 178 179 sysfs_bin_attr_init(&pdata->nvram_attr); 180 pdata->nvram_attr.attr.name = "nvram"; 181 pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR; 182 pdata->nvram_attr.read = ds1742_nvram_read; 183 pdata->nvram_attr.write = ds1742_nvram_write; 184 pdata->nvram_attr.size = pdata->size_nvram; 185 186 /* turn RTC on if it was not on */ 187 ioaddr = pdata->ioaddr_rtc; 188 sec = readb(ioaddr + RTC_SECONDS); 189 if (sec & RTC_STOP) { 190 sec &= RTC_SECONDS_MASK; 191 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 192 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 193 writeb(sec, ioaddr + RTC_SECONDS); 194 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 195 } 196 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG)) 197 dev_warn(&pdev->dev, "voltage-low detected.\n"); 198 199 pdata->last_jiffies = jiffies; 200 platform_set_drvdata(pdev, pdata); 201 rtc = devm_rtc_device_register(&pdev->dev, pdev->name, 202 &ds1742_rtc_ops, THIS_MODULE); 203 if (IS_ERR(rtc)) 204 return PTR_ERR(rtc); 205 206 ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr); 207 if (ret) 208 dev_err(&pdev->dev, "Unable to create sysfs entry: %s\n", 209 pdata->nvram_attr.attr.name); 210 211 return 0; 212 } 213 214 static int ds1742_rtc_remove(struct platform_device *pdev) 215 { 216 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 217 218 sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr); 219 return 0; 220 } 221 222 static struct of_device_id __maybe_unused ds1742_rtc_of_match[] = { 223 { .compatible = "maxim,ds1742", }, 224 { } 225 }; 226 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match); 227 228 static struct platform_driver ds1742_rtc_driver = { 229 .probe = ds1742_rtc_probe, 230 .remove = ds1742_rtc_remove, 231 .driver = { 232 .name = "rtc-ds1742", 233 .owner = THIS_MODULE, 234 .of_match_table = ds1742_rtc_of_match, 235 }, 236 }; 237 238 module_platform_driver(ds1742_rtc_driver); 239 240 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); 241 MODULE_DESCRIPTION("Dallas DS1742 RTC driver"); 242 MODULE_LICENSE("GPL"); 243 MODULE_VERSION(DRV_VERSION); 244 MODULE_ALIAS("platform:rtc-ds1742"); 245