/* rtc-ds3234.c * * Driver for Dallas Semiconductor (DS3234) SPI RTC with Integrated Crystal * and SRAM. * * Copyright (C) 2008 MIMOMax Wireless Ltd. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * */ #include <linux/init.h> #include <linux/module.h> #include <linux/device.h> #include <linux/platform_device.h> #include <linux/rtc.h> #include <linux/spi/spi.h> #include <linux/bcd.h> #define DS3234_REG_SECONDS 0x00 #define DS3234_REG_MINUTES 0x01 #define DS3234_REG_HOURS 0x02 #define DS3234_REG_DAY 0x03 #define DS3234_REG_DATE 0x04 #define DS3234_REG_MONTH 0x05 #define DS3234_REG_YEAR 0x06 #define DS3234_REG_CENTURY (1 << 7) /* Bit 7 of the Month register */ #define DS3234_REG_CONTROL 0x0E #define DS3234_REG_CONT_STAT 0x0F static int ds3234_set_reg(struct device *dev, unsigned char address, unsigned char data) { struct spi_device *spi = to_spi_device(dev); unsigned char buf[2]; /* MSB must be '1' to indicate write */ buf[0] = address | 0x80; buf[1] = data; return spi_write_then_read(spi, buf, 2, NULL, 0); } static int ds3234_get_reg(struct device *dev, unsigned char address, unsigned char *data) { struct spi_device *spi = to_spi_device(dev); *data = address & 0x7f; return spi_write_then_read(spi, data, 1, data, 1); } static int ds3234_read_time(struct device *dev, struct rtc_time *dt) { int err; unsigned char buf[8]; struct spi_device *spi = to_spi_device(dev); buf[0] = 0x00; /* Start address */ err = spi_write_then_read(spi, buf, 1, buf, 8); if (err != 0) return err; /* Seconds, Minutes, Hours, Day, Date, Month, Year */ dt->tm_sec = bcd2bin(buf[0]); dt->tm_min = bcd2bin(buf[1]); dt->tm_hour = bcd2bin(buf[2] & 0x3f); dt->tm_wday = bcd2bin(buf[3]) - 1; /* 0 = Sun */ dt->tm_mday = bcd2bin(buf[4]); dt->tm_mon = bcd2bin(buf[5] & 0x1f) - 1; /* 0 = Jan */ dt->tm_year = bcd2bin(buf[6] & 0xff) + 100; /* Assume 20YY */ return rtc_valid_tm(dt); } static int ds3234_set_time(struct device *dev, struct rtc_time *dt) { ds3234_set_reg(dev, DS3234_REG_SECONDS, bin2bcd(dt->tm_sec)); ds3234_set_reg(dev, DS3234_REG_MINUTES, bin2bcd(dt->tm_min)); ds3234_set_reg(dev, DS3234_REG_HOURS, bin2bcd(dt->tm_hour) & 0x3f); /* 0 = Sun */ ds3234_set_reg(dev, DS3234_REG_DAY, bin2bcd(dt->tm_wday + 1)); ds3234_set_reg(dev, DS3234_REG_DATE, bin2bcd(dt->tm_mday)); /* 0 = Jan */ ds3234_set_reg(dev, DS3234_REG_MONTH, bin2bcd(dt->tm_mon + 1)); /* Assume 20YY although we just want to make sure not to go negative. */ if (dt->tm_year > 100) dt->tm_year -= 100; ds3234_set_reg(dev, DS3234_REG_YEAR, bin2bcd(dt->tm_year)); return 0; } static const struct rtc_class_ops ds3234_rtc_ops = { .read_time = ds3234_read_time, .set_time = ds3234_set_time, }; static int __devinit ds3234_probe(struct spi_device *spi) { struct rtc_device *rtc; unsigned char tmp; int res; spi->mode = SPI_MODE_3; spi->bits_per_word = 8; spi_setup(spi); res = ds3234_get_reg(&spi->dev, DS3234_REG_SECONDS, &tmp); if (res != 0) return res; /* Control settings * * CONTROL_REG * BIT 7 6 5 4 3 2 1 0 * EOSC BBSQW CONV RS2 RS1 INTCN A2IE A1IE * * 0 0 0 1 1 1 0 0 * * CONTROL_STAT_REG * BIT 7 6 5 4 3 2 1 0 * OSF BB32kHz CRATE1 CRATE0 EN32kHz BSY A2F A1F * * 1 0 0 0 1 0 0 0 */ ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp); ds3234_set_reg(&spi->dev, DS3234_REG_CONTROL, tmp & 0x1c); ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp); ds3234_set_reg(&spi->dev, DS3234_REG_CONT_STAT, tmp & 0x88); /* Print our settings */ ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp); dev_info(&spi->dev, "Control Reg: 0x%02x\n", tmp); ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp); dev_info(&spi->dev, "Ctrl/Stat Reg: 0x%02x\n", tmp); rtc = rtc_device_register("ds3234", &spi->dev, &ds3234_rtc_ops, THIS_MODULE); if (IS_ERR(rtc)) return PTR_ERR(rtc); dev_set_drvdata(&spi->dev, rtc); return 0; } static int __devexit ds3234_remove(struct spi_device *spi) { struct rtc_device *rtc = spi_get_drvdata(spi); rtc_device_unregister(rtc); return 0; } static struct spi_driver ds3234_driver = { .driver = { .name = "ds3234", .owner = THIS_MODULE, }, .probe = ds3234_probe, .remove = __devexit_p(ds3234_remove), }; module_spi_driver(ds3234_driver); MODULE_DESCRIPTION("DS3234 SPI RTC driver"); MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>"); MODULE_LICENSE("GPL"); MODULE_ALIAS("spi:ds3234");