drivers/rtc/rtc-r9701.c

   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");