1 /* 2 * ST M48T86 / Dallas DS12887 RTC driver 3 * Copyright (c) 2006 Tower Technologies 4 * 5 * Author: Alessandro Zummo <a.zummo@towertech.it> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * This drivers only supports the clock running in BCD and 24H mode. 12 * If it will be ever adapted to binary and 12H mode, care must be taken 13 * to not introduce bugs. 14 */ 15 16 #include <linux/module.h> 17 #include <linux/rtc.h> 18 #include <linux/platform_device.h> 19 #include <linux/m48t86.h> 20 #include <linux/bcd.h> 21 22 #define M48T86_REG_SEC 0x00 23 #define M48T86_REG_SECALRM 0x01 24 #define M48T86_REG_MIN 0x02 25 #define M48T86_REG_MINALRM 0x03 26 #define M48T86_REG_HOUR 0x04 27 #define M48T86_REG_HOURALRM 0x05 28 #define M48T86_REG_DOW 0x06 /* 1 = sunday */ 29 #define M48T86_REG_DOM 0x07 30 #define M48T86_REG_MONTH 0x08 /* 1 - 12 */ 31 #define M48T86_REG_YEAR 0x09 /* 0 - 99 */ 32 #define M48T86_REG_A 0x0A 33 #define M48T86_REG_B 0x0B 34 #define M48T86_REG_C 0x0C 35 #define M48T86_REG_D 0x0D 36 37 #define M48T86_REG_B_H24 (1 << 1) 38 #define M48T86_REG_B_DM (1 << 2) 39 #define M48T86_REG_B_SET (1 << 7) 40 #define M48T86_REG_D_VRT (1 << 7) 41 42 #define DRV_VERSION "0.1" 43 44 45 static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm) 46 { 47 unsigned char reg; 48 struct platform_device *pdev = to_platform_device(dev); 49 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev); 50 51 reg = ops->readbyte(M48T86_REG_B); 52 53 if (reg & M48T86_REG_B_DM) { 54 /* data (binary) mode */ 55 tm->tm_sec = ops->readbyte(M48T86_REG_SEC); 56 tm->tm_min = ops->readbyte(M48T86_REG_MIN); 57 tm->tm_hour = ops->readbyte(M48T86_REG_HOUR) & 0x3F; 58 tm->tm_mday = ops->readbyte(M48T86_REG_DOM); 59 /* tm_mon is 0-11 */ 60 tm->tm_mon = ops->readbyte(M48T86_REG_MONTH) - 1; 61 tm->tm_year = ops->readbyte(M48T86_REG_YEAR) + 100; 62 tm->tm_wday = ops->readbyte(M48T86_REG_DOW); 63 } else { 64 /* bcd mode */ 65 tm->tm_sec = bcd2bin(ops->readbyte(M48T86_REG_SEC)); 66 tm->tm_min = bcd2bin(ops->readbyte(M48T86_REG_MIN)); 67 tm->tm_hour = bcd2bin(ops->readbyte(M48T86_REG_HOUR) & 0x3F); 68 tm->tm_mday = bcd2bin(ops->readbyte(M48T86_REG_DOM)); 69 /* tm_mon is 0-11 */ 70 tm->tm_mon = bcd2bin(ops->readbyte(M48T86_REG_MONTH)) - 1; 71 tm->tm_year = bcd2bin(ops->readbyte(M48T86_REG_YEAR)) + 100; 72 tm->tm_wday = bcd2bin(ops->readbyte(M48T86_REG_DOW)); 73 } 74 75 /* correct the hour if the clock is in 12h mode */ 76 if (!(reg & M48T86_REG_B_H24)) 77 if (ops->readbyte(M48T86_REG_HOUR) & 0x80) 78 tm->tm_hour += 12; 79 80 return rtc_valid_tm(tm); 81 } 82 83 static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm) 84 { 85 unsigned char reg; 86 struct platform_device *pdev = to_platform_device(dev); 87 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev); 88 89 reg = ops->readbyte(M48T86_REG_B); 90 91 /* update flag and 24h mode */ 92 reg |= M48T86_REG_B_SET | M48T86_REG_B_H24; 93 ops->writebyte(reg, M48T86_REG_B); 94 95 if (reg & M48T86_REG_B_DM) { 96 /* data (binary) mode */ 97 ops->writebyte(tm->tm_sec, M48T86_REG_SEC); 98 ops->writebyte(tm->tm_min, M48T86_REG_MIN); 99 ops->writebyte(tm->tm_hour, M48T86_REG_HOUR); 100 ops->writebyte(tm->tm_mday, M48T86_REG_DOM); 101 ops->writebyte(tm->tm_mon + 1, M48T86_REG_MONTH); 102 ops->writebyte(tm->tm_year % 100, M48T86_REG_YEAR); 103 ops->writebyte(tm->tm_wday, M48T86_REG_DOW); 104 } else { 105 /* bcd mode */ 106 ops->writebyte(bin2bcd(tm->tm_sec), M48T86_REG_SEC); 107 ops->writebyte(bin2bcd(tm->tm_min), M48T86_REG_MIN); 108 ops->writebyte(bin2bcd(tm->tm_hour), M48T86_REG_HOUR); 109 ops->writebyte(bin2bcd(tm->tm_mday), M48T86_REG_DOM); 110 ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_REG_MONTH); 111 ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_REG_YEAR); 112 ops->writebyte(bin2bcd(tm->tm_wday), M48T86_REG_DOW); 113 } 114 115 /* update ended */ 116 reg &= ~M48T86_REG_B_SET; 117 ops->writebyte(reg, M48T86_REG_B); 118 119 return 0; 120 } 121 122 static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq) 123 { 124 unsigned char reg; 125 struct platform_device *pdev = to_platform_device(dev); 126 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev); 127 128 reg = ops->readbyte(M48T86_REG_B); 129 130 seq_printf(seq, "mode\t\t: %s\n", 131 (reg & M48T86_REG_B_DM) ? "binary" : "bcd"); 132 133 reg = ops->readbyte(M48T86_REG_D); 134 135 seq_printf(seq, "battery\t\t: %s\n", 136 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted"); 137 138 return 0; 139 } 140 141 static const struct rtc_class_ops m48t86_rtc_ops = { 142 .read_time = m48t86_rtc_read_time, 143 .set_time = m48t86_rtc_set_time, 144 .proc = m48t86_rtc_proc, 145 }; 146 147 static int m48t86_rtc_probe(struct platform_device *dev) 148 { 149 unsigned char reg; 150 struct m48t86_ops *ops = dev_get_platdata(&dev->dev); 151 struct rtc_device *rtc; 152 153 rtc = devm_rtc_device_register(&dev->dev, "m48t86", 154 &m48t86_rtc_ops, THIS_MODULE); 155 156 if (IS_ERR(rtc)) 157 return PTR_ERR(rtc); 158 159 platform_set_drvdata(dev, rtc); 160 161 /* read battery status */ 162 reg = ops->readbyte(M48T86_REG_D); 163 dev_info(&dev->dev, "battery %s\n", 164 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted"); 165 166 return 0; 167 } 168 169 static struct platform_driver m48t86_rtc_platform_driver = { 170 .driver = { 171 .name = "rtc-m48t86", 172 }, 173 .probe = m48t86_rtc_probe, 174 }; 175 176 module_platform_driver(m48t86_rtc_platform_driver); 177 178 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 179 MODULE_DESCRIPTION("M48T86 RTC driver"); 180 MODULE_LICENSE("GPL"); 181 MODULE_VERSION(DRV_VERSION); 182 MODULE_ALIAS("platform:rtc-m48t86"); 183