1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Driver for Epson RTC-9701JE 4 * 5 * Copyright (C) 2008 Magnus Damm 6 * 7 * Based on rtc-max6902.c 8 * 9 * Copyright (C) 2006 8D Technologies inc. 10 * Copyright (C) 2004 Compulab Ltd. 11 */ 12 13 #include <linux/module.h> 14 #include <linux/kernel.h> 15 #include <linux/platform_device.h> 16 #include <linux/device.h> 17 #include <linux/init.h> 18 #include <linux/rtc.h> 19 #include <linux/spi/spi.h> 20 #include <linux/bcd.h> 21 #include <linux/delay.h> 22 #include <linux/bitops.h> 23 24 #define RSECCNT 0x00 /* Second Counter */ 25 #define RMINCNT 0x01 /* Minute Counter */ 26 #define RHRCNT 0x02 /* Hour Counter */ 27 #define RWKCNT 0x03 /* Week Counter */ 28 #define RDAYCNT 0x04 /* Day Counter */ 29 #define RMONCNT 0x05 /* Month Counter */ 30 #define RYRCNT 0x06 /* Year Counter */ 31 #define R100CNT 0x07 /* Y100 Counter */ 32 #define RMINAR 0x08 /* Minute Alarm */ 33 #define RHRAR 0x09 /* Hour Alarm */ 34 #define RWKAR 0x0a /* Week/Day Alarm */ 35 #define RTIMCNT 0x0c /* Interval Timer */ 36 #define REXT 0x0d /* Extension Register */ 37 #define RFLAG 0x0e /* RTC Flag Register */ 38 #define RCR 0x0f /* RTC Control Register */ 39 40 static int write_reg(struct device *dev, int address, unsigned char data) 41 { 42 struct spi_device *spi = to_spi_device(dev); 43 unsigned char buf[2]; 44 45 buf[0] = address & 0x7f; 46 buf[1] = data; 47 48 return spi_write(spi, buf, ARRAY_SIZE(buf)); 49 } 50 51 static int read_regs(struct device *dev, unsigned char *regs, int no_regs) 52 { 53 struct spi_device *spi = to_spi_device(dev); 54 u8 txbuf[1], rxbuf[1]; 55 int k, ret; 56 57 ret = 0; 58 59 for (k = 0; ret == 0 && k < no_regs; k++) { 60 txbuf[0] = 0x80 | regs[k]; 61 ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1); 62 regs[k] = rxbuf[0]; 63 } 64 65 return ret; 66 } 67 68 static int r9701_get_datetime(struct device *dev, struct rtc_time *dt) 69 { 70 int ret; 71 unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT, 72 RDAYCNT, RMONCNT, RYRCNT }; 73 74 ret = read_regs(dev, buf, ARRAY_SIZE(buf)); 75 if (ret) 76 return ret; 77 78 memset(dt, 0, sizeof(*dt)); 79 80 dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */ 81 dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */ 82 dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */ 83 84 dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */ 85 dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */ 86 dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */ 87 88 /* the rtc device may contain illegal values on power up 89 * according to the data sheet. make sure they are valid. 90 */ 91 92 return 0; 93 } 94 95 static int r9701_set_datetime(struct device *dev, struct rtc_time *dt) 96 { 97 int ret, year; 98 99 year = dt->tm_year + 1900; 100 if (year >= 2100 || year < 2000) 101 return -EINVAL; 102 103 ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour)); 104 ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min)); 105 ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec)); 106 ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday)); 107 ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1)); 108 ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100)); 109 ret = ret ? ret : write_reg(dev, RWKCNT, 1 << dt->tm_wday); 110 111 return ret; 112 } 113 114 static const struct rtc_class_ops r9701_rtc_ops = { 115 .read_time = r9701_get_datetime, 116 .set_time = r9701_set_datetime, 117 }; 118 119 static int r9701_probe(struct spi_device *spi) 120 { 121 struct rtc_device *rtc; 122 struct rtc_time dt; 123 unsigned char tmp; 124 int res; 125 126 tmp = R100CNT; 127 res = read_regs(&spi->dev, &tmp, 1); 128 if (res || tmp != 0x20) { 129 dev_err(&spi->dev, "cannot read RTC register\n"); 130 return -ENODEV; 131 } 132 133 /* 134 * The device seems to be present. Now check if the registers 135 * contain invalid values. If so, try to write a default date: 136 * 2000/1/1 00:00:00 137 */ 138 if (r9701_get_datetime(&spi->dev, &dt)) { 139 dev_info(&spi->dev, "trying to repair invalid date/time\n"); 140 dt.tm_sec = 0; 141 dt.tm_min = 0; 142 dt.tm_hour = 0; 143 dt.tm_mday = 1; 144 dt.tm_mon = 0; 145 dt.tm_year = 100; 146 147 if (r9701_set_datetime(&spi->dev, &dt) || 148 r9701_get_datetime(&spi->dev, &dt)) { 149 dev_err(&spi->dev, "cannot repair RTC register\n"); 150 return -ENODEV; 151 } 152 } 153 154 rtc = devm_rtc_device_register(&spi->dev, "r9701", 155 &r9701_rtc_ops, THIS_MODULE); 156 if (IS_ERR(rtc)) 157 return PTR_ERR(rtc); 158 159 spi_set_drvdata(spi, rtc); 160 161 return 0; 162 } 163 164 static struct spi_driver r9701_driver = { 165 .driver = { 166 .name = "rtc-r9701", 167 }, 168 .probe = r9701_probe, 169 }; 170 171 module_spi_driver(r9701_driver); 172 173 MODULE_DESCRIPTION("r9701 spi RTC driver"); 174 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>"); 175 MODULE_LICENSE("GPL"); 176 MODULE_ALIAS("spi:rtc-r9701"); 177