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213 lines
5.7 KiB
213 lines
5.7 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Dallas DS1302 RTC Support |
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* |
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* Copyright (C) 2002 David McCullough |
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* Copyright (C) 2003 - 2007 Paul Mundt |
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*/ |
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#include <linux/bcd.h> |
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#include <linux/init.h> |
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#include <linux/io.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/of.h> |
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#include <linux/rtc.h> |
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#include <linux/spi/spi.h> |
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#define RTC_CMD_READ 0x81 /* Read command */ |
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#define RTC_CMD_WRITE 0x80 /* Write command */ |
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#define RTC_CMD_WRITE_ENABLE 0x00 /* Write enable */ |
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#define RTC_CMD_WRITE_DISABLE 0x80 /* Write disable */ |
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#define RTC_ADDR_RAM0 0x20 /* Address of RAM0 */ |
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#define RTC_ADDR_TCR 0x08 /* Address of trickle charge register */ |
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#define RTC_CLCK_BURST 0x1F /* Address of clock burst */ |
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#define RTC_CLCK_LEN 0x08 /* Size of clock burst */ |
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#define RTC_ADDR_CTRL 0x07 /* Address of control register */ |
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#define RTC_ADDR_YEAR 0x06 /* Address of year register */ |
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#define RTC_ADDR_DAY 0x05 /* Address of day of week register */ |
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#define RTC_ADDR_MON 0x04 /* Address of month register */ |
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#define RTC_ADDR_DATE 0x03 /* Address of day of month register */ |
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#define RTC_ADDR_HOUR 0x02 /* Address of hour register */ |
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#define RTC_ADDR_MIN 0x01 /* Address of minute register */ |
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#define RTC_ADDR_SEC 0x00 /* Address of second register */ |
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static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *time) |
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{ |
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struct spi_device *spi = dev_get_drvdata(dev); |
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u8 buf[1 + RTC_CLCK_LEN]; |
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u8 *bp; |
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int status; |
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/* Enable writing */ |
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bp = buf; |
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*bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE; |
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*bp++ = RTC_CMD_WRITE_ENABLE; |
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status = spi_write_then_read(spi, buf, 2, |
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NULL, 0); |
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if (status) |
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return status; |
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/* Write registers starting at the first time/date address. */ |
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bp = buf; |
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*bp++ = RTC_CLCK_BURST << 1 | RTC_CMD_WRITE; |
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*bp++ = bin2bcd(time->tm_sec); |
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*bp++ = bin2bcd(time->tm_min); |
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*bp++ = bin2bcd(time->tm_hour); |
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*bp++ = bin2bcd(time->tm_mday); |
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*bp++ = bin2bcd(time->tm_mon + 1); |
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*bp++ = time->tm_wday + 1; |
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*bp++ = bin2bcd(time->tm_year % 100); |
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*bp++ = RTC_CMD_WRITE_DISABLE; |
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/* use write-then-read since dma from stack is nonportable */ |
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return spi_write_then_read(spi, buf, sizeof(buf), |
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NULL, 0); |
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} |
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static int ds1302_rtc_get_time(struct device *dev, struct rtc_time *time) |
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{ |
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struct spi_device *spi = dev_get_drvdata(dev); |
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u8 addr = RTC_CLCK_BURST << 1 | RTC_CMD_READ; |
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u8 buf[RTC_CLCK_LEN - 1]; |
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int status; |
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/* Use write-then-read to get all the date/time registers |
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* since dma from stack is nonportable |
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*/ |
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status = spi_write_then_read(spi, &addr, sizeof(addr), |
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buf, sizeof(buf)); |
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if (status < 0) |
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return status; |
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/* Decode the registers */ |
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time->tm_sec = bcd2bin(buf[RTC_ADDR_SEC]); |
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time->tm_min = bcd2bin(buf[RTC_ADDR_MIN]); |
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time->tm_hour = bcd2bin(buf[RTC_ADDR_HOUR]); |
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time->tm_wday = buf[RTC_ADDR_DAY] - 1; |
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time->tm_mday = bcd2bin(buf[RTC_ADDR_DATE]); |
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time->tm_mon = bcd2bin(buf[RTC_ADDR_MON]) - 1; |
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time->tm_year = bcd2bin(buf[RTC_ADDR_YEAR]) + 100; |
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return 0; |
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} |
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static const struct rtc_class_ops ds1302_rtc_ops = { |
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.read_time = ds1302_rtc_get_time, |
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.set_time = ds1302_rtc_set_time, |
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}; |
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static int ds1302_probe(struct spi_device *spi) |
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{ |
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struct rtc_device *rtc; |
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u8 addr; |
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u8 buf[4]; |
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u8 *bp; |
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int status; |
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/* Sanity check board setup data. This may be hooked up |
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* in 3wire mode, but we don't care. Note that unless |
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* there's an inverter in place, this needs SPI_CS_HIGH! |
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*/ |
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if (spi->bits_per_word && (spi->bits_per_word != 8)) { |
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dev_err(&spi->dev, "bad word length\n"); |
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return -EINVAL; |
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} else if (spi->max_speed_hz > 2000000) { |
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dev_err(&spi->dev, "speed is too high\n"); |
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return -EINVAL; |
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} else if (spi->mode & SPI_CPHA) { |
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dev_err(&spi->dev, "bad mode\n"); |
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return -EINVAL; |
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} |
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addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ; |
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status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1); |
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if (status < 0) { |
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dev_err(&spi->dev, "control register read error %d\n", |
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status); |
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return status; |
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} |
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if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) { |
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status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1); |
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if (status < 0) { |
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dev_err(&spi->dev, "control register read error %d\n", |
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status); |
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return status; |
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} |
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if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) { |
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dev_err(&spi->dev, "junk in control register\n"); |
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return -ENODEV; |
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} |
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} |
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if (buf[0] == 0) { |
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bp = buf; |
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*bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE; |
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*bp++ = RTC_CMD_WRITE_DISABLE; |
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status = spi_write_then_read(spi, buf, 2, NULL, 0); |
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if (status < 0) { |
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dev_err(&spi->dev, "control register write error %d\n", |
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status); |
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return status; |
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} |
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addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ; |
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status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1); |
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if (status < 0) { |
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dev_err(&spi->dev, |
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"error %d reading control register\n", |
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status); |
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return status; |
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} |
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if (buf[0] != RTC_CMD_WRITE_DISABLE) { |
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dev_err(&spi->dev, "failed to detect chip\n"); |
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return -ENODEV; |
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} |
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} |
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spi_set_drvdata(spi, spi); |
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rtc = devm_rtc_device_register(&spi->dev, "ds1302", |
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&ds1302_rtc_ops, THIS_MODULE); |
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if (IS_ERR(rtc)) { |
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status = PTR_ERR(rtc); |
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dev_err(&spi->dev, "error %d registering rtc\n", status); |
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return status; |
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} |
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return 0; |
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} |
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static int ds1302_remove(struct spi_device *spi) |
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{ |
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spi_set_drvdata(spi, NULL); |
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return 0; |
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} |
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#ifdef CONFIG_OF |
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static const struct of_device_id ds1302_dt_ids[] = { |
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{ .compatible = "maxim,ds1302", }, |
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{ /* sentinel */ } |
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}; |
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MODULE_DEVICE_TABLE(of, ds1302_dt_ids); |
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#endif |
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static struct spi_driver ds1302_driver = { |
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.driver.name = "rtc-ds1302", |
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.driver.of_match_table = of_match_ptr(ds1302_dt_ids), |
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.probe = ds1302_probe, |
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.remove = ds1302_remove, |
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}; |
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module_spi_driver(ds1302_driver); |
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MODULE_DESCRIPTION("Dallas DS1302 RTC driver"); |
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MODULE_AUTHOR("Paul Mundt, David McCullough"); |
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MODULE_LICENSE("GPL v2");
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