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 11 #include <linux/bcd.h> 12 #include <linux/init.h> 13 #include <linux/kernel.h> 14 #include <linux/delay.h> 15 #include <linux/jiffies.h> 16 #include <linux/rtc.h> 17 #include <linux/platform_device.h> 18 #include <linux/io.h> 19 20 #define DRV_VERSION "0.1" 21 22 #define RTC_REG_SIZE 0x800 23 #define RTC_OFFSET 0x7f8 24 25 #define RTC_CONTROL (RTC_OFFSET + 0) 26 #define RTC_CENTURY (RTC_OFFSET + 0) 27 #define RTC_SECONDS (RTC_OFFSET + 1) 28 #define RTC_MINUTES (RTC_OFFSET + 2) 29 #define RTC_HOURS (RTC_OFFSET + 3) 30 #define RTC_DAY (RTC_OFFSET + 4) 31 #define RTC_DATE (RTC_OFFSET + 5) 32 #define RTC_MONTH (RTC_OFFSET + 6) 33 #define RTC_YEAR (RTC_OFFSET + 7) 34 35 #define RTC_CENTURY_MASK 0x3f 36 #define RTC_SECONDS_MASK 0x7f 37 #define RTC_DAY_MASK 0x07 38 39 /* Bits in the Control/Century register */ 40 #define RTC_WRITE 0x80 41 #define RTC_READ 0x40 42 43 /* Bits in the Seconds register */ 44 #define RTC_STOP 0x80 45 46 /* Bits in the Day register */ 47 #define RTC_BATT_FLAG 0x80 48 49 struct rtc_plat_data { 50 struct rtc_device *rtc; 51 void __iomem *ioaddr; 52 unsigned long baseaddr; 53 unsigned long last_jiffies; 54 }; 55 56 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm) 57 { 58 struct platform_device *pdev = to_platform_device(dev); 59 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 60 void __iomem *ioaddr = pdata->ioaddr; 61 u8 century; 62 63 century = BIN2BCD((tm->tm_year + 1900) / 100); 64 65 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 66 67 writeb(BIN2BCD(tm->tm_year % 100), ioaddr + RTC_YEAR); 68 writeb(BIN2BCD(tm->tm_mon + 1), ioaddr + RTC_MONTH); 69 writeb(BIN2BCD(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY); 70 writeb(BIN2BCD(tm->tm_mday), ioaddr + RTC_DATE); 71 writeb(BIN2BCD(tm->tm_hour), ioaddr + RTC_HOURS); 72 writeb(BIN2BCD(tm->tm_min), ioaddr + RTC_MINUTES); 73 writeb(BIN2BCD(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS); 74 75 /* RTC_CENTURY and RTC_CONTROL share same register */ 76 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY); 77 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 78 return 0; 79 } 80 81 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm) 82 { 83 struct platform_device *pdev = to_platform_device(dev); 84 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 85 void __iomem *ioaddr = pdata->ioaddr; 86 unsigned int year, month, day, hour, minute, second, week; 87 unsigned int century; 88 89 /* give enough time to update RTC in case of continuous read */ 90 if (pdata->last_jiffies == jiffies) 91 msleep(1); 92 pdata->last_jiffies = jiffies; 93 writeb(RTC_READ, ioaddr + RTC_CONTROL); 94 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; 95 minute = readb(ioaddr + RTC_MINUTES); 96 hour = readb(ioaddr + RTC_HOURS); 97 day = readb(ioaddr + RTC_DATE); 98 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK; 99 month = readb(ioaddr + RTC_MONTH); 100 year = readb(ioaddr + RTC_YEAR); 101 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 102 writeb(0, ioaddr + RTC_CONTROL); 103 tm->tm_sec = BCD2BIN(second); 104 tm->tm_min = BCD2BIN(minute); 105 tm->tm_hour = BCD2BIN(hour); 106 tm->tm_mday = BCD2BIN(day); 107 tm->tm_wday = BCD2BIN(week); 108 tm->tm_mon = BCD2BIN(month) - 1; 109 /* year is 1900 + tm->tm_year */ 110 tm->tm_year = BCD2BIN(year) + BCD2BIN(century) * 100 - 1900; 111 112 if (rtc_valid_tm(tm) < 0) { 113 dev_err(dev, "retrieved date/time is not valid.\n"); 114 rtc_time_to_tm(0, tm); 115 } 116 return 0; 117 } 118 119 static struct rtc_class_ops ds1742_rtc_ops = { 120 .read_time = ds1742_rtc_read_time, 121 .set_time = ds1742_rtc_set_time, 122 }; 123 124 static ssize_t ds1742_nvram_read(struct kobject *kobj, char *buf, 125 loff_t pos, size_t size) 126 { 127 struct platform_device *pdev = 128 to_platform_device(container_of(kobj, struct device, kobj)); 129 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 130 void __iomem *ioaddr = pdata->ioaddr; 131 ssize_t count; 132 133 for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--) 134 *buf++ = readb(ioaddr + pos++); 135 return count; 136 } 137 138 static ssize_t ds1742_nvram_write(struct kobject *kobj, char *buf, 139 loff_t pos, size_t size) 140 { 141 struct platform_device *pdev = 142 to_platform_device(container_of(kobj, struct device, kobj)); 143 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 144 void __iomem *ioaddr = pdata->ioaddr; 145 ssize_t count; 146 147 for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--) 148 writeb(*buf++, ioaddr + pos++); 149 return count; 150 } 151 152 static struct bin_attribute ds1742_nvram_attr = { 153 .attr = { 154 .name = "nvram", 155 .mode = S_IRUGO | S_IWUGO, 156 .owner = THIS_MODULE, 157 }, 158 .size = RTC_OFFSET, 159 .read = ds1742_nvram_read, 160 .write = ds1742_nvram_write, 161 }; 162 163 static int __init ds1742_rtc_probe(struct platform_device *pdev) 164 { 165 struct rtc_device *rtc; 166 struct resource *res; 167 unsigned int cen, sec; 168 struct rtc_plat_data *pdata = NULL; 169 void __iomem *ioaddr = NULL; 170 int ret = 0; 171 172 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 173 if (!res) 174 return -ENODEV; 175 pdata = kzalloc(sizeof(*pdata), GFP_KERNEL); 176 if (!pdata) 177 return -ENOMEM; 178 if (!request_mem_region(res->start, RTC_REG_SIZE, pdev->name)) { 179 ret = -EBUSY; 180 goto out; 181 } 182 pdata->baseaddr = res->start; 183 ioaddr = ioremap(pdata->baseaddr, RTC_REG_SIZE); 184 if (!ioaddr) { 185 ret = -ENOMEM; 186 goto out; 187 } 188 pdata->ioaddr = ioaddr; 189 190 /* turn RTC on if it was not on */ 191 sec = readb(ioaddr + RTC_SECONDS); 192 if (sec & RTC_STOP) { 193 sec &= RTC_SECONDS_MASK; 194 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; 195 writeb(RTC_WRITE, ioaddr + RTC_CONTROL); 196 writeb(sec, ioaddr + RTC_SECONDS); 197 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); 198 } 199 if (readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG) 200 dev_warn(&pdev->dev, "voltage-low detected.\n"); 201 202 rtc = rtc_device_register(pdev->name, &pdev->dev, 203 &ds1742_rtc_ops, THIS_MODULE); 204 if (IS_ERR(rtc)) { 205 ret = PTR_ERR(rtc); 206 goto out; 207 } 208 pdata->rtc = rtc; 209 pdata->last_jiffies = jiffies; 210 platform_set_drvdata(pdev, pdata); 211 sysfs_create_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr); 212 return 0; 213 out: 214 if (ioaddr) 215 iounmap(ioaddr); 216 if (pdata->baseaddr) 217 release_mem_region(pdata->baseaddr, RTC_REG_SIZE); 218 kfree(pdata); 219 return ret; 220 } 221 222 static int __devexit ds1742_rtc_remove(struct platform_device *pdev) 223 { 224 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 225 226 sysfs_remove_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr); 227 rtc_device_unregister(pdata->rtc); 228 iounmap(pdata->ioaddr); 229 release_mem_region(pdata->baseaddr, RTC_REG_SIZE); 230 kfree(pdata); 231 return 0; 232 } 233 234 static struct platform_driver ds1742_rtc_driver = { 235 .probe = ds1742_rtc_probe, 236 .remove = __devexit_p(ds1742_rtc_remove), 237 .driver = { 238 .name = "ds1742", 239 .owner = THIS_MODULE, 240 }, 241 }; 242 243 static __init int ds1742_init(void) 244 { 245 return platform_driver_register(&ds1742_rtc_driver); 246 } 247 248 static __exit void ds1742_exit(void) 249 { 250 return platform_driver_unregister(&ds1742_rtc_driver); 251 } 252 253 module_init(ds1742_init); 254 module_exit(ds1742_exit); 255 256 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); 257 MODULE_DESCRIPTION("Dallas DS1742 RTC driver"); 258 MODULE_LICENSE("GPL"); 259 MODULE_VERSION(DRV_VERSION); 260