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145 lines
3.7 KiB
145 lines
3.7 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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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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#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 <[email protected]>"); |
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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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