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235 lines
5.8 KiB
235 lines
5.8 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC |
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* |
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* Copyright (C) 2008 Mercury IMC Ltd |
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* Written by Mark Jackson <[email protected]> |
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* |
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* NOTE: Currently this driver only supports the bare minimum for read |
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* and write the RTC. The extra features provided by the chip family |
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* (alarms, trickle charger, different control registers) are unavailable. |
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*/ |
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#include <linux/init.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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#include <linux/bcd.h> |
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#include <linux/slab.h> |
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#include <linux/of.h> |
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#define DS1390_REG_100THS 0x00 |
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#define DS1390_REG_SECONDS 0x01 |
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#define DS1390_REG_MINUTES 0x02 |
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#define DS1390_REG_HOURS 0x03 |
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#define DS1390_REG_DAY 0x04 |
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#define DS1390_REG_DATE 0x05 |
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#define DS1390_REG_MONTH_CENT 0x06 |
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#define DS1390_REG_YEAR 0x07 |
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#define DS1390_REG_ALARM_100THS 0x08 |
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#define DS1390_REG_ALARM_SECONDS 0x09 |
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#define DS1390_REG_ALARM_MINUTES 0x0A |
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#define DS1390_REG_ALARM_HOURS 0x0B |
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#define DS1390_REG_ALARM_DAY_DATE 0x0C |
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#define DS1390_REG_CONTROL 0x0D |
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#define DS1390_REG_STATUS 0x0E |
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#define DS1390_REG_TRICKLE 0x0F |
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#define DS1390_TRICKLE_CHARGER_ENABLE 0xA0 |
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#define DS1390_TRICKLE_CHARGER_250_OHM 0x01 |
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#define DS1390_TRICKLE_CHARGER_2K_OHM 0x02 |
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#define DS1390_TRICKLE_CHARGER_4K_OHM 0x03 |
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#define DS1390_TRICKLE_CHARGER_NO_DIODE 0x04 |
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#define DS1390_TRICKLE_CHARGER_DIODE 0x08 |
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struct ds1390 { |
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struct rtc_device *rtc; |
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u8 txrx_buf[9]; /* cmd + 8 registers */ |
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}; |
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static void ds1390_set_reg(struct device *dev, unsigned char address, |
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unsigned char data) |
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{ |
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struct spi_device *spi = to_spi_device(dev); |
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unsigned char buf[2]; |
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/* MSB must be '1' to write */ |
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buf[0] = address | 0x80; |
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buf[1] = data; |
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spi_write(spi, buf, 2); |
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} |
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static int ds1390_get_reg(struct device *dev, unsigned char address, |
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unsigned char *data) |
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{ |
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struct spi_device *spi = to_spi_device(dev); |
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struct ds1390 *chip = dev_get_drvdata(dev); |
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int status; |
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if (!data) |
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return -EINVAL; |
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/* Clear MSB to indicate read */ |
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chip->txrx_buf[0] = address & 0x7f; |
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/* do the i/o */ |
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status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1); |
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if (status != 0) |
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return status; |
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*data = chip->txrx_buf[0]; |
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return 0; |
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} |
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static void ds1390_trickle_of_init(struct spi_device *spi) |
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{ |
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u32 ohms = 0; |
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u8 value; |
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if (of_property_read_u32(spi->dev.of_node, "trickle-resistor-ohms", |
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&ohms)) |
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goto out; |
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/* Enable charger */ |
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value = DS1390_TRICKLE_CHARGER_ENABLE; |
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if (of_property_read_bool(spi->dev.of_node, "trickle-diode-disable")) |
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value |= DS1390_TRICKLE_CHARGER_NO_DIODE; |
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else |
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value |= DS1390_TRICKLE_CHARGER_DIODE; |
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/* Resistor select */ |
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switch (ohms) { |
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case 250: |
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value |= DS1390_TRICKLE_CHARGER_250_OHM; |
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break; |
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case 2000: |
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value |= DS1390_TRICKLE_CHARGER_2K_OHM; |
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break; |
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case 4000: |
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value |= DS1390_TRICKLE_CHARGER_4K_OHM; |
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break; |
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default: |
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dev_warn(&spi->dev, |
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"Unsupported ohm value %02ux in dt\n", ohms); |
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return; |
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} |
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ds1390_set_reg(&spi->dev, DS1390_REG_TRICKLE, value); |
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out: |
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return; |
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} |
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static int ds1390_read_time(struct device *dev, struct rtc_time *dt) |
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{ |
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struct spi_device *spi = to_spi_device(dev); |
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struct ds1390 *chip = dev_get_drvdata(dev); |
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int status; |
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/* build the message */ |
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chip->txrx_buf[0] = DS1390_REG_SECONDS; |
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/* do the i/o */ |
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status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8); |
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if (status != 0) |
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return status; |
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/* The chip sends data in this order: |
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* Seconds, Minutes, Hours, Day, Date, Month / Century, Year */ |
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dt->tm_sec = bcd2bin(chip->txrx_buf[0]); |
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dt->tm_min = bcd2bin(chip->txrx_buf[1]); |
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dt->tm_hour = bcd2bin(chip->txrx_buf[2]); |
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dt->tm_wday = bcd2bin(chip->txrx_buf[3]); |
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dt->tm_mday = bcd2bin(chip->txrx_buf[4]); |
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/* mask off century bit */ |
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dt->tm_mon = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1; |
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/* adjust for century bit */ |
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dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0); |
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return 0; |
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} |
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static int ds1390_set_time(struct device *dev, struct rtc_time *dt) |
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{ |
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struct spi_device *spi = to_spi_device(dev); |
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struct ds1390 *chip = dev_get_drvdata(dev); |
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/* build the message */ |
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chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80; |
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chip->txrx_buf[1] = bin2bcd(dt->tm_sec); |
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chip->txrx_buf[2] = bin2bcd(dt->tm_min); |
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chip->txrx_buf[3] = bin2bcd(dt->tm_hour); |
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chip->txrx_buf[4] = bin2bcd(dt->tm_wday); |
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chip->txrx_buf[5] = bin2bcd(dt->tm_mday); |
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chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) | |
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((dt->tm_year > 99) ? 0x80 : 0x00); |
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chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100); |
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/* do the i/o */ |
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return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0); |
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} |
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static const struct rtc_class_ops ds1390_rtc_ops = { |
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.read_time = ds1390_read_time, |
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.set_time = ds1390_set_time, |
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}; |
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static int ds1390_probe(struct spi_device *spi) |
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{ |
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unsigned char tmp; |
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struct ds1390 *chip; |
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int res; |
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spi->mode = SPI_MODE_3; |
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spi->bits_per_word = 8; |
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spi_setup(spi); |
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chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL); |
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if (!chip) |
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return -ENOMEM; |
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spi_set_drvdata(spi, chip); |
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res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp); |
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if (res != 0) { |
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dev_err(&spi->dev, "unable to read device\n"); |
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return res; |
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} |
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if (spi->dev.of_node) |
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ds1390_trickle_of_init(spi); |
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chip->rtc = devm_rtc_device_register(&spi->dev, "ds1390", |
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&ds1390_rtc_ops, THIS_MODULE); |
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if (IS_ERR(chip->rtc)) { |
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dev_err(&spi->dev, "unable to register device\n"); |
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res = PTR_ERR(chip->rtc); |
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} |
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return res; |
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} |
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static const struct of_device_id ds1390_of_match[] = { |
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{ .compatible = "dallas,ds1390" }, |
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{} |
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}; |
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MODULE_DEVICE_TABLE(of, ds1390_of_match); |
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static struct spi_driver ds1390_driver = { |
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.driver = { |
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.name = "rtc-ds1390", |
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.of_match_table = of_match_ptr(ds1390_of_match), |
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}, |
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.probe = ds1390_probe, |
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}; |
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module_spi_driver(ds1390_driver); |
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MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver"); |
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MODULE_AUTHOR("Mark Jackson <[email protected]>"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("spi:rtc-ds1390");
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