LXR linux/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
  40static 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
  51static 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
  68static 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
  95static 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
 114static const struct rtc_class_ops r9701_rtc_ops = {
 115        .read_time      = r9701_get_datetime,
 116        .set_time       = r9701_set_datetime,
 117};
 118
 119static 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
 164static struct spi_driver r9701_driver = {
 165        .driver = {
 166                .name   = "rtc-r9701",
 167        },
 168        .probe  = r9701_probe,
 169};
 170
 171module_spi_driver(r9701_driver);
 172
 173MODULE_DESCRIPTION("r9701 spi RTC driver");
 174MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
 175MODULE_LICENSE("GPL");
 176MODULE_ALIAS("spi:rtc-r9701");
 177