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![Andrew F. Davis](/assets/img/avatar_default.png)
An spi_driver does not need to set an owner, it will be populated by the driver core. Signed-off-by: Andrew F. Davis <afd@ti.com> Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Mark Brown <broonie@kernel.org>
209 lines
5.4 KiB
C
209 lines
5.4 KiB
C
/*
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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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* 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/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 < 0 ? ret : rtc_valid_tm(tm);
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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 <n.voss@weinmann.de>");
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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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