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206 lines
5.3 KiB
206 lines
5.3 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* |
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* Driver for ST M41T93 SPI RTC |
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* |
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* (c) 2010 Nikolaus Voss, Weinmann Medical GmbH |
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*/ |
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#include <linux/bcd.h> |
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#include <linux/kernel.h> |
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#include <linux/module.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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#define M41T93_REG_SSEC 0 |
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#define M41T93_REG_ST_SEC 1 |
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#define M41T93_REG_MIN 2 |
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#define M41T93_REG_CENT_HOUR 3 |
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#define M41T93_REG_WDAY 4 |
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#define M41T93_REG_DAY 5 |
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#define M41T93_REG_MON 6 |
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#define M41T93_REG_YEAR 7 |
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#define M41T93_REG_ALM_HOUR_HT 0xc |
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#define M41T93_REG_FLAGS 0xf |
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#define M41T93_FLAG_ST (1 << 7) |
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#define M41T93_FLAG_OF (1 << 2) |
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#define M41T93_FLAG_BL (1 << 4) |
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#define M41T93_FLAG_HT (1 << 6) |
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static inline int m41t93_set_reg(struct spi_device *spi, u8 addr, u8 data) |
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{ |
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u8 buf[2]; |
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/* MSB must be '1' to write */ |
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buf[0] = addr | 0x80; |
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buf[1] = data; |
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return spi_write(spi, buf, sizeof(buf)); |
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} |
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static int m41t93_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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int tmp; |
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u8 buf[9] = {0x80}; /* write cmd + 8 data bytes */ |
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u8 * const data = &buf[1]; /* ptr to first data byte */ |
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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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if (tm->tm_year < 100) { |
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dev_warn(&spi->dev, "unsupported date (before 2000-01-01).\n"); |
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return -EINVAL; |
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} |
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tmp = spi_w8r8(spi, M41T93_REG_FLAGS); |
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if (tmp < 0) |
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return tmp; |
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if (tmp & M41T93_FLAG_OF) { |
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dev_warn(&spi->dev, "OF bit is set, resetting.\n"); |
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m41t93_set_reg(spi, M41T93_REG_FLAGS, tmp & ~M41T93_FLAG_OF); |
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tmp = spi_w8r8(spi, M41T93_REG_FLAGS); |
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if (tmp < 0) { |
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return tmp; |
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} else if (tmp & M41T93_FLAG_OF) { |
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/* OF cannot be immediately reset: oscillator has to be |
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* restarted. */ |
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u8 reset_osc = buf[M41T93_REG_ST_SEC] | M41T93_FLAG_ST; |
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dev_warn(&spi->dev, |
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"OF bit is still set, kickstarting clock.\n"); |
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m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc); |
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reset_osc &= ~M41T93_FLAG_ST; |
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m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc); |
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} |
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} |
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data[M41T93_REG_SSEC] = 0; |
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data[M41T93_REG_ST_SEC] = bin2bcd(tm->tm_sec); |
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data[M41T93_REG_MIN] = bin2bcd(tm->tm_min); |
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data[M41T93_REG_CENT_HOUR] = bin2bcd(tm->tm_hour) | |
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((tm->tm_year/100-1) << 6); |
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data[M41T93_REG_DAY] = bin2bcd(tm->tm_mday); |
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data[M41T93_REG_WDAY] = bin2bcd(tm->tm_wday + 1); |
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data[M41T93_REG_MON] = bin2bcd(tm->tm_mon + 1); |
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data[M41T93_REG_YEAR] = bin2bcd(tm->tm_year % 100); |
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return spi_write(spi, buf, sizeof(buf)); |
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} |
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static int m41t93_get_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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const u8 start_addr = 0; |
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u8 buf[8]; |
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int century_after_1900; |
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int tmp; |
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int ret = 0; |
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/* Check status of clock. Two states must be considered: |
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1. halt bit (HT) is set: the clock is running but update of readout |
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registers has been disabled due to power failure. This is normal |
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case after poweron. Time is valid after resetting HT bit. |
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2. oscillator fail bit (OF) is set: time is invalid. |
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*/ |
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tmp = spi_w8r8(spi, M41T93_REG_ALM_HOUR_HT); |
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if (tmp < 0) |
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return tmp; |
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if (tmp & M41T93_FLAG_HT) { |
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dev_dbg(&spi->dev, "HT bit is set, reenable clock update.\n"); |
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m41t93_set_reg(spi, M41T93_REG_ALM_HOUR_HT, |
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tmp & ~M41T93_FLAG_HT); |
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} |
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tmp = spi_w8r8(spi, M41T93_REG_FLAGS); |
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if (tmp < 0) |
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return tmp; |
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if (tmp & M41T93_FLAG_OF) { |
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ret = -EINVAL; |
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dev_warn(&spi->dev, "OF bit is set, write time to restart.\n"); |
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} |
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if (tmp & M41T93_FLAG_BL) |
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dev_warn(&spi->dev, "BL bit is set, replace battery.\n"); |
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/* read actual time/date */ |
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tmp = spi_write_then_read(spi, &start_addr, 1, buf, sizeof(buf)); |
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if (tmp < 0) |
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return tmp; |
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tm->tm_sec = bcd2bin(buf[M41T93_REG_ST_SEC]); |
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tm->tm_min = bcd2bin(buf[M41T93_REG_MIN]); |
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tm->tm_hour = bcd2bin(buf[M41T93_REG_CENT_HOUR] & 0x3f); |
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tm->tm_mday = bcd2bin(buf[M41T93_REG_DAY]); |
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tm->tm_mon = bcd2bin(buf[M41T93_REG_MON]) - 1; |
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tm->tm_wday = bcd2bin(buf[M41T93_REG_WDAY] & 0x0f) - 1; |
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century_after_1900 = (buf[M41T93_REG_CENT_HOUR] >> 6) + 1; |
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tm->tm_year = bcd2bin(buf[M41T93_REG_YEAR]) + century_after_1900 * 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 ret; |
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} |
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static const struct rtc_class_ops m41t93_rtc_ops = { |
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.read_time = m41t93_get_time, |
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.set_time = m41t93_set_time, |
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}; |
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static struct spi_driver m41t93_driver; |
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static int m41t93_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, M41T93_REG_WDAY); |
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if (res < 0 || (res & 0xf8) != 0) { |
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dev_err(&spi->dev, "not found 0x%x.\n", res); |
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return -ENODEV; |
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} |
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rtc = devm_rtc_device_register(&spi->dev, m41t93_driver.driver.name, |
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&m41t93_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 m41t93_driver = { |
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.driver = { |
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.name = "rtc-m41t93", |
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}, |
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.probe = m41t93_probe, |
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}; |
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module_spi_driver(m41t93_driver); |
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MODULE_AUTHOR("Nikolaus Voss <[email protected]>"); |
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MODULE_DESCRIPTION("Driver for ST M41T93 SPI RTC"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("spi:rtc-m41t93");
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