| /* |
| * 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 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 = devm_rtc_device_register(&spi->dev, m41t94_driver.driver.name, |
| &m41t94_rtc_ops, THIS_MODULE); |
| if (IS_ERR(rtc)) |
| return PTR_ERR(rtc); |
| |
| dev_set_drvdata(&spi->dev, rtc); |
| |
| return 0; |
| } |
| |
| static int m41t94_remove(struct spi_device *spi) |
| { |
| return 0; |
| } |
| |
| static struct spi_driver m41t94_driver = { |
| .driver = { |
| .name = "rtc-m41t94", |
| .owner = THIS_MODULE, |
| }, |
| .probe = m41t94_probe, |
| .remove = m41t94_remove, |
| }; |
| |
| module_spi_driver(m41t94_driver); |
| |
| MODULE_AUTHOR("Kim B. Heino <Kim.Heino@bluegiga.com>"); |
| MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC"); |
| MODULE_LICENSE("GPL"); |
| MODULE_ALIAS("spi:rtc-m41t94"); |