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/init.h> 17 #include <linux/kernel.h> 18 #include <linux/gfp.h> 19 #include <linux/delay.h> 20 #include <linux/jiffies.h> 21 #include <linux/rtc.h> 22 #include <linux/platform_device.h> 23 #include <linux/io.h> 24 #include <linux/module.h> 25 26 #define DRV_VERSION "0.4" 27 28 #define RTC_SIZE 8 29 30 #define RTC_CONTROL 0 31 #define RTC_CENTURY 0 32 #define RTC_SECONDS 1 33 #define RTC_MINUTES 2 34 #define RTC_HOURS 3 35 #define RTC_DAY 4 36 #define RTC_DATE 5 37 #define RTC_MONTH 6 38 #define RTC_YEAR 7 39 40 #define RTC_CENTURY_MASK 0x3f 41 #define RTC_SECONDS_MASK 0x7f 42 #define RTC_DAY_MASK 0x07 43 44 /* Bits in the Control/Century register */ 45 #define RTC_WRITE 0x80 46 #define RTC_READ 0x40 47 48 /* Bits in the Seconds register */ 49 #define RTC_STOP 0x80 50 51 /* Bits in the Day register */ 52 #define RTC_BATT_FLAG 0x80 53 54 struct rtc_plat_data { 55 void __iomem *ioaddr_nvram; 56 void __iomem *ioaddr_rtc; 57 size_t size_nvram; 58 unsigned long last_jiffies; 59 struct bin_attribute nvram_attr; 60 }; 61 62 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm) 63 { 64 struct platform_device *pdev = to_platform_device(dev); 65 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 66 void __iomem *ioaddr = pdata->ioaddr_rtc; 67 u8 century; 68 69 century = bin2bcd((tm->tm_year + 1900) / 100); 70 71 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 72 73 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR); 74 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH); 75 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY); 76 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE); 77 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS); 78 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES); 79 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS); 80 81 /* RTC_CENTURY and RTC_CONTROL share same register */ 82 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY); 83 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 84 return 0; 85 } 86 87 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm) 88 { 89 struct platform_device *pdev = to_platform_device(dev); 90 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 91 void __iomem *ioaddr = pdata->ioaddr_rtc; 92 unsigned int year, month, day, hour, minute, second, week; 93 unsigned int century; 94 95 /* give enough time to update RTC in case of continuous read */ 96 if (pdata->last_jiffies == jiffies) 97 msleep(1); 98 pdata->last_jiffies = jiffies; 99 writeb(RTC_READ, ioaddr + RTC_CONTROL); 100 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; 101 minute = readb(ioaddr + RTC_MINUTES); 102 hour = readb(ioaddr + RTC_HOURS); 103 day = readb(ioaddr + RTC_DATE); 104 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK; 105 month = readb(ioaddr + RTC_MONTH); 106 year = readb(ioaddr + RTC_YEAR); 107 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 108 writeb(0, ioaddr + RTC_CONTROL); 109 tm->tm_sec = bcd2bin(second); 110 tm->tm_min = bcd2bin(minute); 111 tm->tm_hour = bcd2bin(hour); 112 tm->tm_mday = bcd2bin(day); 113 tm->tm_wday = bcd2bin(week); 114 tm->tm_mon = bcd2bin(month) - 1; 115 /* year is 1900 + tm->tm_year */ 116 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; 117 118 return rtc_valid_tm(tm); 119 } 120 121 static const struct rtc_class_ops ds1742_rtc_ops = { 122 .read_time = ds1742_rtc_read_time, 123 .set_time = ds1742_rtc_set_time, 124 }; 125 126 static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj, 127 struct bin_attribute *bin_attr, 128 char *buf, loff_t pos, size_t size) 129 { 130 struct device *dev = container_of(kobj, struct device, kobj); 131 struct platform_device *pdev = to_platform_device(dev); 132 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 133 void __iomem *ioaddr = pdata->ioaddr_nvram; 134 ssize_t count; 135 136 for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--) 137 *buf++ = readb(ioaddr + pos++); 138 return count; 139 } 140 141 static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj, 142 struct bin_attribute *bin_attr, 143 char *buf, loff_t pos, size_t size) 144 { 145 struct device *dev = container_of(kobj, struct device, kobj); 146 struct platform_device *pdev = to_platform_device(dev); 147 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 148 void __iomem *ioaddr = pdata->ioaddr_nvram; 149 ssize_t count; 150 151 for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--) 152 writeb(*buf++, ioaddr + pos++); 153 return count; 154 } 155 156 static int ds1742_rtc_probe(struct platform_device *pdev) 157 { 158 struct rtc_device *rtc; 159 struct resource *res; 160 unsigned int cen, sec; 161 struct rtc_plat_data *pdata; 162 void __iomem *ioaddr; 163 int ret = 0; 164 165 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 166 if (!pdata) 167 return -ENOMEM; 168 169 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 170 ioaddr = devm_ioremap_resource(&pdev->dev, res); 171 if (IS_ERR(ioaddr)) 172 return PTR_ERR(ioaddr); 173 174 pdata->ioaddr_nvram = ioaddr; 175 pdata->size_nvram = resource_size(res) - RTC_SIZE; 176 pdata->ioaddr_rtc = ioaddr + pdata->size_nvram; 177 178 sysfs_bin_attr_init(&pdata->nvram_attr); 179 pdata->nvram_attr.attr.name = "nvram"; 180 pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR; 181 pdata->nvram_attr.read = ds1742_nvram_read; 182 pdata->nvram_attr.write = ds1742_nvram_write; 183 pdata->nvram_attr.size = pdata->size_nvram; 184 185 /* turn RTC on if it was not on */ 186 ioaddr = pdata->ioaddr_rtc; 187 sec = readb(ioaddr + RTC_SECONDS); 188 if (sec & RTC_STOP) { 189 sec &= RTC_SECONDS_MASK; 190 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 191 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 192 writeb(sec, ioaddr + RTC_SECONDS); 193 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 194 } 195 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG)) 196 dev_warn(&pdev->dev, "voltage-low detected.\n"); 197 198 pdata->last_jiffies = jiffies; 199 platform_set_drvdata(pdev, pdata); 200 rtc = devm_rtc_device_register(&pdev->dev, pdev->name, 201 &ds1742_rtc_ops, THIS_MODULE); 202 if (IS_ERR(rtc)) 203 return PTR_ERR(rtc); 204 205 ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr); 206 207 return ret; 208 } 209 210 static int ds1742_rtc_remove(struct platform_device *pdev) 211 { 212 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 213 214 sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr); 215 return 0; 216 } 217 218 static struct platform_driver ds1742_rtc_driver = { 219 .probe = ds1742_rtc_probe, 220 .remove = ds1742_rtc_remove, 221 .driver = { 222 .name = "rtc-ds1742", 223 .owner = THIS_MODULE, 224 }, 225 }; 226 227 module_platform_driver(ds1742_rtc_driver); 228 229 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); 230 MODULE_DESCRIPTION("Dallas DS1742 RTC driver"); 231 MODULE_LICENSE("GPL"); 232 MODULE_VERSION(DRV_VERSION); 233 MODULE_ALIAS("platform:rtc-ds1742"); 234