/* * Driver for ST M41T94 SPI RTC * * Copyright (C) 2008 Kim B. Heino * * 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/module.h> #include <linux/kernel.h> #include <linux/platform_device.h> #include <linux/rtc.h> #include <linux/spi/spi.h> #include <linux/bcd.h> #define M41T94_REG_SECONDS 0x01 #define M41T94_REG_MINUTES 0x02 #define M41T94_REG_HOURS 0x03 #define M41T94_REG_WDAY 0x04 #define M41T94_REG_DAY 0x05 #define M41T94_REG_MONTH 0x06 #define M41T94_REG_YEAR 0x07 #define M41T94_REG_HT 0x0c #define M41T94_BIT_HALT 0x40 #define M41T94_BIT_STOP 0x80 #define M41T94_BIT_CB 0x40 #define M41T94_BIT_CEB 0x80 static int m41t94_set_time(struct device *dev, struct rtc_time *tm) { struct spi_device *spi = to_spi_device(dev); u8 buf[8]; /* write cmd + 7 registers */ dev_dbg(dev, "%s secs=%d, mins=%d, " "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", "write", tm->tm_sec, tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */ buf[M41T94_REG_SECONDS] = BIN2BCD(tm->tm_sec); buf[M41T94_REG_MINUTES] = BIN2BCD(tm->tm_min); buf[M41T94_REG_HOURS] = BIN2BCD(tm->tm_hour); buf[M41T94_REG_WDAY] = BIN2BCD(tm->tm_wday + 1); buf[M41T94_REG_DAY] = BIN2BCD(tm->tm_mday); buf[M41T94_REG_MONTH] = BIN2BCD(tm->tm_mon + 1); buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB; if (tm->tm_year >= 100) buf[M41T94_REG_HOURS] |= M41T94_BIT_CB; buf[M41T94_REG_YEAR] = BIN2BCD(tm->tm_year % 100); return spi_write(spi, buf, 8); } static int m41t94_read_time(struct device *dev, struct rtc_time *tm) { struct spi_device *spi = to_spi_device(dev); u8 buf[2]; int ret, hour; /* clear halt update bit */ ret = spi_w8r8(spi, M41T94_REG_HT); if (ret < 0) return ret; if (ret & M41T94_BIT_HALT) { buf[0] = 0x80 | M41T94_REG_HT; buf[1] = ret & ~M41T94_BIT_HALT; spi_write(spi, buf, 2); } /* clear stop bit */ ret = spi_w8r8(spi, M41T94_REG_SECONDS); if (ret < 0) return ret; if (ret & M41T94_BIT_STOP) { buf[0] = 0x80 | M41T94_REG_SECONDS; buf[1] = ret & ~M41T94_BIT_STOP; spi_write(spi, buf, 2); } tm->tm_sec = BCD2BIN(spi_w8r8(spi, M41T94_REG_SECONDS)); tm->tm_min = BCD2BIN(spi_w8r8(spi, M41T94_REG_MINUTES)); hour = spi_w8r8(spi, M41T94_REG_HOURS); tm->tm_hour = BCD2BIN(hour & 0x3f); tm->tm_wday = BCD2BIN(spi_w8r8(spi, M41T94_REG_WDAY)) - 1; tm->tm_mday = BCD2BIN(spi_w8r8(spi, M41T94_REG_DAY)); tm->tm_mon = BCD2BIN(spi_w8r8(spi, M41T94_REG_MONTH)) - 1; tm->tm_year = BCD2BIN(spi_w8r8(spi, M41T94_REG_YEAR)); if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB)) tm->tm_year += 100; dev_dbg(dev, "%s secs=%d, mins=%d, " "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", "read", tm->tm_sec, tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); /* initial clock setting can be undefined */ return rtc_valid_tm(tm); } static const struct rtc_class_ops m41t94_rtc_ops = { .read_time = m41t94_read_time, .set_time = m41t94_set_time, }; static struct spi_driver m41t94_driver; static int __devinit m41t94_probe(struct spi_device *spi) { struct rtc_device *rtc; int res; spi->bits_per_word = 8; spi_setup(spi); res = spi_w8r8(spi, M41T94_REG_SECONDS); if (res < 0) { dev_err(&spi->dev, "not found.\n"); return res; } rtc = rtc_device_register(m41t94_driver.driver.name, &spi->dev, &m41t94_rtc_ops, THIS_MODULE); if (IS_ERR(rtc)) return PTR_ERR(rtc); dev_set_drvdata(&spi->dev, rtc); return 0; } static int __devexit m41t94_remove(struct spi_device *spi) { struct rtc_device *rtc = platform_get_drvdata(spi); if (rtc) rtc_device_unregister(rtc); return 0; } static struct spi_driver m41t94_driver = { .driver = { .name = "rtc-m41t94", .bus = &spi_bus_type, .owner = THIS_MODULE, }, .probe = m41t94_probe, .remove = __devexit_p(m41t94_remove), }; static __init int m41t94_init(void) { return spi_register_driver(&m41t94_driver); } module_init(m41t94_init); static __exit void m41t94_exit(void) { spi_unregister_driver(&m41t94_driver); } module_exit(m41t94_exit); MODULE_AUTHOR("Kim B. Heino <Kim.Heino@bluegiga.com>"); MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC"); MODULE_LICENSE("GPL");