149 lines
3.8 KiB
C
149 lines
3.8 KiB
C
/*
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* Driver for ST M41T94 SPI RTC
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*
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* Copyright (C) 2008 Kim B. Heino
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/rtc.h>
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#include <linux/spi/spi.h>
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#include <linux/bcd.h>
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#define M41T94_REG_SECONDS 0x01
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#define M41T94_REG_MINUTES 0x02
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#define M41T94_REG_HOURS 0x03
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#define M41T94_REG_WDAY 0x04
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#define M41T94_REG_DAY 0x05
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#define M41T94_REG_MONTH 0x06
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#define M41T94_REG_YEAR 0x07
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#define M41T94_REG_HT 0x0c
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#define M41T94_BIT_HALT 0x40
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#define M41T94_BIT_STOP 0x80
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#define M41T94_BIT_CB 0x40
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#define M41T94_BIT_CEB 0x80
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static int m41t94_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct spi_device *spi = to_spi_device(dev);
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u8 buf[8]; /* write cmd + 7 registers */
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dev_dbg(dev, "%s secs=%d, mins=%d, "
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"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
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"write", tm->tm_sec, tm->tm_min,
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tm->tm_hour, tm->tm_mday,
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tm->tm_mon, tm->tm_year, tm->tm_wday);
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buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */
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buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);
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buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min);
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buf[M41T94_REG_HOURS] = bin2bcd(tm->tm_hour);
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buf[M41T94_REG_WDAY] = bin2bcd(tm->tm_wday + 1);
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buf[M41T94_REG_DAY] = bin2bcd(tm->tm_mday);
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buf[M41T94_REG_MONTH] = bin2bcd(tm->tm_mon + 1);
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buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB;
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if (tm->tm_year >= 100)
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buf[M41T94_REG_HOURS] |= M41T94_BIT_CB;
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buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100);
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return spi_write(spi, buf, 8);
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}
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static int m41t94_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct spi_device *spi = to_spi_device(dev);
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u8 buf[2];
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int ret, hour;
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/* clear halt update bit */
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ret = spi_w8r8(spi, M41T94_REG_HT);
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if (ret < 0)
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return ret;
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if (ret & M41T94_BIT_HALT) {
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buf[0] = 0x80 | M41T94_REG_HT;
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buf[1] = ret & ~M41T94_BIT_HALT;
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spi_write(spi, buf, 2);
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}
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/* clear stop bit */
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ret = spi_w8r8(spi, M41T94_REG_SECONDS);
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if (ret < 0)
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return ret;
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if (ret & M41T94_BIT_STOP) {
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buf[0] = 0x80 | M41T94_REG_SECONDS;
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buf[1] = ret & ~M41T94_BIT_STOP;
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spi_write(spi, buf, 2);
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}
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tm->tm_sec = bcd2bin(spi_w8r8(spi, M41T94_REG_SECONDS));
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tm->tm_min = bcd2bin(spi_w8r8(spi, M41T94_REG_MINUTES));
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hour = spi_w8r8(spi, M41T94_REG_HOURS);
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tm->tm_hour = bcd2bin(hour & 0x3f);
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tm->tm_wday = bcd2bin(spi_w8r8(spi, M41T94_REG_WDAY)) - 1;
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tm->tm_mday = bcd2bin(spi_w8r8(spi, M41T94_REG_DAY));
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tm->tm_mon = bcd2bin(spi_w8r8(spi, M41T94_REG_MONTH)) - 1;
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tm->tm_year = bcd2bin(spi_w8r8(spi, M41T94_REG_YEAR));
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if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB))
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tm->tm_year += 100;
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dev_dbg(dev, "%s secs=%d, mins=%d, "
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"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
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"read", tm->tm_sec, tm->tm_min,
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tm->tm_hour, tm->tm_mday,
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tm->tm_mon, tm->tm_year, tm->tm_wday);
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return 0;
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}
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static const struct rtc_class_ops m41t94_rtc_ops = {
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.read_time = m41t94_read_time,
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.set_time = m41t94_set_time,
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};
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static struct spi_driver m41t94_driver;
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static int m41t94_probe(struct spi_device *spi)
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{
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struct rtc_device *rtc;
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int res;
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spi->bits_per_word = 8;
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spi_setup(spi);
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res = spi_w8r8(spi, M41T94_REG_SECONDS);
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if (res < 0) {
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dev_err(&spi->dev, "not found.\n");
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return res;
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}
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rtc = devm_rtc_device_register(&spi->dev, m41t94_driver.driver.name,
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&m41t94_rtc_ops, THIS_MODULE);
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if (IS_ERR(rtc))
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return PTR_ERR(rtc);
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spi_set_drvdata(spi, rtc);
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return 0;
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}
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static struct spi_driver m41t94_driver = {
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.driver = {
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.name = "rtc-m41t94",
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},
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.probe = m41t94_probe,
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};
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module_spi_driver(m41t94_driver);
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MODULE_AUTHOR("Kim B. Heino <Kim.Heino@bluegiga.com>");
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MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("spi:rtc-m41t94");
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