drivers/rtc/rtc-r9701.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Driver for Epson RTC-9701JE
0004  *
0005  * Copyright (C) 2008 Magnus Damm
0006  *
0007  * Based on rtc-max6902.c
0008  *
0009  * Copyright (C) 2006 8D Technologies inc.
0010  * Copyright (C) 2004 Compulab Ltd.
0011  */
0012
0013 #include <linux/module.h>
0014 #include <linux/kernel.h>
0015 #include <linux/platform_device.h>
0016 #include <linux/device.h>
0017 #include <linux/init.h>
0018 #include <linux/rtc.h>
0019 #include <linux/spi/spi.h>
0020 #include <linux/bcd.h>
0021 #include <linux/delay.h>
0022 #include <linux/bitops.h>
0023
0024 #define RSECCNT 0x00    /* Second Counter */
0025 #define RMINCNT 0x01    /* Minute Counter */
0026 #define RHRCNT  0x02    /* Hour Counter */
0027 #define RWKCNT  0x03    /* Week Counter */
0028 #define RDAYCNT 0x04    /* Day Counter */
0029 #define RMONCNT 0x05    /* Month Counter */
0030 #define RYRCNT  0x06    /* Year Counter */
0031 #define R100CNT 0x07    /* Y100 Counter */
0032 #define RMINAR  0x08    /* Minute Alarm */
0033 #define RHRAR   0x09    /* Hour Alarm */
0034 #define RWKAR   0x0a    /* Week/Day Alarm */
0035 #define RTIMCNT 0x0c    /* Interval Timer */
0036 #define REXT    0x0d    /* Extension Register */
0037 #define RFLAG   0x0e    /* RTC Flag Register */
0038 #define RCR 0x0f    /* RTC Control Register */
0039
0040 static int write_reg(struct device *dev, int address, unsigned char data)
0041 {
0042     struct spi_device *spi = to_spi_device(dev);
0043     unsigned char buf[2];
0044
0045     buf[0] = address & 0x7f;
0046     buf[1] = data;
0047
0048     return spi_write(spi, buf, ARRAY_SIZE(buf));
0049 }
0050
0051 static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
0052 {
0053     struct spi_device *spi = to_spi_device(dev);
0054     u8 txbuf[1], rxbuf[1];
0055     int k, ret;
0056
0057     ret = 0;
0058
0059     for (k = 0; ret == 0 && k < no_regs; k++) {
0060         txbuf[0] = 0x80 | regs[k];
0061         ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
0062         regs[k] = rxbuf[0];
0063     }
0064
0065     return ret;
0066 }
0067
0068 static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
0069 {
0070     int ret;
0071     unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
0072                 RDAYCNT, RMONCNT, RYRCNT };
0073
0074     ret = read_regs(dev, buf, ARRAY_SIZE(buf));
0075     if (ret)
0076         return ret;
0077
0078     dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
0079     dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
0080     dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
0081
0082     dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
0083     dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
0084     dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
0085
0086     return 0;
0087 }
0088
0089 static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
0090 {
0091     int ret;
0092
0093     ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
0094     ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
0095     ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
0096     ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
0097     ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
0098     ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
0099
0100     return ret;
0101 }
0102
0103 static const struct rtc_class_ops r9701_rtc_ops = {
0104     .read_time  = r9701_get_datetime,
0105     .set_time   = r9701_set_datetime,
0106 };
0107
0108 static int r9701_probe(struct spi_device *spi)
0109 {
0110     struct rtc_device *rtc;
0111     unsigned char tmp;
0112     int res;
0113
0114     tmp = R100CNT;
0115     res = read_regs(&spi->dev, &tmp, 1);
0116     if (res || tmp != 0x20) {
0117         dev_err(&spi->dev, "cannot read RTC register\n");
0118         return -ENODEV;
0119     }
0120
0121     rtc = devm_rtc_allocate_device(&spi->dev);
0122     if (IS_ERR(rtc))
0123         return PTR_ERR(rtc);
0124
0125     spi_set_drvdata(spi, rtc);
0126     rtc->ops = &r9701_rtc_ops;
0127     rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
0128     rtc->range_max = RTC_TIMESTAMP_END_2099;
0129
0130     return devm_rtc_register_device(rtc);
0131 }
0132
0133 static struct spi_driver r9701_driver = {
0134     .driver = {
0135         .name   = "rtc-r9701",
0136     },
0137     .probe  = r9701_probe,
0138 };
0139
0140 module_spi_driver(r9701_driver);
0141
0142 MODULE_DESCRIPTION("r9701 spi RTC driver");
0143 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
0144 MODULE_LICENSE("GPL");
0145 MODULE_ALIAS("spi:rtc-r9701");