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