1 /* 2 * Driver for Epson RTC-9701JE 3 * 4 * Copyright (C) 2008 Magnus Damm 5 * 6 * Based on rtc-max6902.c 7 * 8 * Copyright (C) 2006 8D Technologies inc. 9 * Copyright (C) 2004 Compulab Ltd. 10 * 11 * This program is free software; you can redistribute it and/or modify 12 * it under the terms of the GNU General Public License version 2 as 13 * published by the Free Software Foundation. 14 */ 15 16 #include <linux/module.h> 17 #include <linux/kernel.h> 18 #include <linux/platform_device.h> 19 #include <linux/device.h> 20 #include <linux/init.h> 21 #include <linux/rtc.h> 22 #include <linux/spi/spi.h> 23 #include <linux/bcd.h> 24 #include <linux/delay.h> 25 #include <linux/bitops.h> 26 27 #define RSECCNT 0x00 /* Second Counter */ 28 #define RMINCNT 0x01 /* Minute Counter */ 29 #define RHRCNT 0x02 /* Hour Counter */ 30 #define RWKCNT 0x03 /* Week Counter */ 31 #define RDAYCNT 0x04 /* Day Counter */ 32 #define RMONCNT 0x05 /* Month Counter */ 33 #define RYRCNT 0x06 /* Year Counter */ 34 #define R100CNT 0x07 /* Y100 Counter */ 35 #define RMINAR 0x08 /* Minute Alarm */ 36 #define RHRAR 0x09 /* Hour Alarm */ 37 #define RWKAR 0x0a /* Week/Day Alarm */ 38 #define RTIMCNT 0x0c /* Interval Timer */ 39 #define REXT 0x0d /* Extension Register */ 40 #define RFLAG 0x0e /* RTC Flag Register */ 41 #define RCR 0x0f /* RTC Control Register */ 42 43 static int write_reg(struct device *dev, int address, unsigned char data) 44 { 45 struct spi_device *spi = to_spi_device(dev); 46 unsigned char buf[2]; 47 48 buf[0] = address & 0x7f; 49 buf[1] = data; 50 51 return spi_write(spi, buf, ARRAY_SIZE(buf)); 52 } 53 54 static int read_regs(struct device *dev, unsigned char *regs, int no_regs) 55 { 56 struct spi_device *spi = to_spi_device(dev); 57 u8 txbuf[1], rxbuf[1]; 58 int k, ret; 59 60 ret = 0; 61 62 for (k = 0; ret == 0 && k < no_regs; k++) { 63 txbuf[0] = 0x80 | regs[k]; 64 ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1); 65 regs[k] = rxbuf[0]; 66 } 67 68 return ret; 69 } 70 71 static int r9701_get_datetime(struct device *dev, struct rtc_time *dt) 72 { 73 int ret; 74 unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT, 75 RDAYCNT, RMONCNT, RYRCNT }; 76 77 ret = read_regs(dev, buf, ARRAY_SIZE(buf)); 78 if (ret) 79 return ret; 80 81 memset(dt, 0, sizeof(*dt)); 82 83 dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */ 84 dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */ 85 dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */ 86 87 dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */ 88 dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */ 89 dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */ 90 91 /* the rtc device may contain illegal values on power up 92 * according to the data sheet. make sure they are valid. 93 */ 94 95 return 0; 96 } 97 98 static int r9701_set_datetime(struct device *dev, struct rtc_time *dt) 99 { 100 int ret, year; 101 102 year = dt->tm_year + 1900; 103 if (year >= 2100 || year < 2000) 104 return -EINVAL; 105 106 ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour)); 107 ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min)); 108 ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec)); 109 ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday)); 110 ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1)); 111 ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100)); 112 ret = ret ? ret : write_reg(dev, RWKCNT, 1 << dt->tm_wday); 113 114 return ret; 115 } 116 117 static const struct rtc_class_ops r9701_rtc_ops = { 118 .read_time = r9701_get_datetime, 119 .set_time = r9701_set_datetime, 120 }; 121 122 static int r9701_probe(struct spi_device *spi) 123 { 124 struct rtc_device *rtc; 125 struct rtc_time dt; 126 unsigned char tmp; 127 int res; 128 129 tmp = R100CNT; 130 res = read_regs(&spi->dev, &tmp, 1); 131 if (res || tmp != 0x20) { 132 dev_err(&spi->dev, "cannot read RTC register\n"); 133 return -ENODEV; 134 } 135 136 /* 137 * The device seems to be present. Now check if the registers 138 * contain invalid values. If so, try to write a default date: 139 * 2000/1/1 00:00:00 140 */ 141 if (r9701_get_datetime(&spi->dev, &dt)) { 142 dev_info(&spi->dev, "trying to repair invalid date/time\n"); 143 dt.tm_sec = 0; 144 dt.tm_min = 0; 145 dt.tm_hour = 0; 146 dt.tm_mday = 1; 147 dt.tm_mon = 0; 148 dt.tm_year = 100; 149 150 if (r9701_set_datetime(&spi->dev, &dt) || 151 r9701_get_datetime(&spi->dev, &dt)) { 152 dev_err(&spi->dev, "cannot repair RTC register\n"); 153 return -ENODEV; 154 } 155 } 156 157 rtc = devm_rtc_device_register(&spi->dev, "r9701", 158 &r9701_rtc_ops, THIS_MODULE); 159 if (IS_ERR(rtc)) 160 return PTR_ERR(rtc); 161 162 spi_set_drvdata(spi, rtc); 163 164 return 0; 165 } 166 167 static struct spi_driver r9701_driver = { 168 .driver = { 169 .name = "rtc-r9701", 170 }, 171 .probe = r9701_probe, 172 }; 173 174 module_spi_driver(r9701_driver); 175 176 MODULE_DESCRIPTION("r9701 spi RTC driver"); 177 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>"); 178 MODULE_LICENSE("GPL"); 179 MODULE_ALIAS("spi:rtc-r9701"); 180