// SPDX-License-Identifier: GPL-2.0-only/* * rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC * * Copyright (C) 2008 Mercury IMC Ltd * Written by Mark Jackson <mpfj@mimc.co.uk> * * NOTE: Currently this driver only supports the bare minimum for read * and write the RTC. The extra features provided by the chip family * (alarms, trickle charger, different control registers) are unavailable. */ #include <linux/init.h>#include <linux/module.h>#include <linux/platform_device.h>#include <linux/rtc.h>#include <linux/spi/spi.h>#include <linux/bcd.h>#include <linux/slab.h>#include <linux/of.h> #define DS1390_REG_100THS		0x00#define DS1390_REG_SECONDS		0x01#define DS1390_REG_MINUTES		0x02#define DS1390_REG_HOURS		0x03#define DS1390_REG_DAY			0x04#define DS1390_REG_DATE			0x05#define DS1390_REG_MONTH_CENT		0x06#define DS1390_REG_YEAR			0x07 #define DS1390_REG_ALARM_100THS		0x08#define DS1390_REG_ALARM_SECONDS	0x09#define DS1390_REG_ALARM_MINUTES	0x0A#define DS1390_REG_ALARM_HOURS		0x0B#define DS1390_REG_ALARM_DAY_DATE	0x0C #define DS1390_REG_CONTROL		0x0D#define DS1390_REG_STATUS		0x0E#define DS1390_REG_TRICKLE		0x0F #define DS1390_TRICKLE_CHARGER_ENABLE	0xA0#define DS1390_TRICKLE_CHARGER_250_OHM	0x01#define DS1390_TRICKLE_CHARGER_2K_OHM	0x02#define DS1390_TRICKLE_CHARGER_4K_OHM	0x03#define DS1390_TRICKLE_CHARGER_NO_DIODE	0x04#define DS1390_TRICKLE_CHARGER_DIODE	0x08 struct ds1390 {	struct rtc_device *rtc;	u8 txrx_buf[9];	/* cmd + 8 registers */}; static void ds1390_set_reg(struct device *dev, unsigned char address,			   unsigned char data){	struct spi_device *spi = to_spi_device(dev);	unsigned char buf[2]; 	/* MSB must be '1' to write */	buf[0] = address | 0x80;	buf[1] = data; 	spi_write(spi, buf, 2);} static int ds1390_get_reg(struct device *dev, unsigned char address,				unsigned char *data){	struct spi_device *spi = to_spi_device(dev);	struct ds1390 *chip = dev_get_drvdata(dev);	int status; 	if (!data)		return -EINVAL; 	/* Clear MSB to indicate read */	chip->txrx_buf[0] = address & 0x7f;	/* do the i/o */	status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);	if (status != 0)		return status; 	*data = chip->txrx_buf[0]; 	return 0;} static void ds1390_trickle_of_init(struct spi_device *spi){	u32 ohms = 0;	u8 value; 	if (of_property_read_u32(spi->dev.of_node, "trickle-resistor-ohms",				 &ohms))		goto out; 	/* Enable charger */	value = DS1390_TRICKLE_CHARGER_ENABLE;	if (of_property_read_bool(spi->dev.of_node, "trickle-diode-disable"))		value |= DS1390_TRICKLE_CHARGER_NO_DIODE;	else		value |= DS1390_TRICKLE_CHARGER_DIODE; 	/* Resistor select */	switch (ohms) {	case 250:		value |= DS1390_TRICKLE_CHARGER_250_OHM;		break;	case 2000:		value |= DS1390_TRICKLE_CHARGER_2K_OHM;		break;	case 4000:		value |= DS1390_TRICKLE_CHARGER_4K_OHM;		break;	default:		dev_warn(&spi->dev,			 "Unsupported ohm value %02ux in dt\n", ohms);		return;	} 	ds1390_set_reg(&spi->dev, DS1390_REG_TRICKLE, value); out:	return;} static int ds1390_read_time(struct device *dev, struct rtc_time *dt){	struct spi_device *spi = to_spi_device(dev);	struct ds1390 *chip = dev_get_drvdata(dev);	int status; 	/* build the message */	chip->txrx_buf[0] = DS1390_REG_SECONDS; 	/* do the i/o */	status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 7);	if (status != 0)		return status; 	/* The chip sends data in this order:	 * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */	dt->tm_sec	= bcd2bin(chip->txrx_buf[0]);	dt->tm_min	= bcd2bin(chip->txrx_buf[1]);	dt->tm_hour	= bcd2bin(chip->txrx_buf[2]);	dt->tm_wday	= bcd2bin(chip->txrx_buf[3]);	dt->tm_mday	= bcd2bin(chip->txrx_buf[4]);	/* mask off century bit */	dt->tm_mon	= bcd2bin(chip->txrx_buf[5] & 0x7f) - 1;	/* adjust for century bit */	dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0); 	return 0;} static int ds1390_set_time(struct device *dev, struct rtc_time *dt){	struct spi_device *spi = to_spi_device(dev);	struct ds1390 *chip = dev_get_drvdata(dev); 	/* build the message */	chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80;	chip->txrx_buf[1] = bin2bcd(dt->tm_sec);	chip->txrx_buf[2] = bin2bcd(dt->tm_min);	chip->txrx_buf[3] = bin2bcd(dt->tm_hour);	chip->txrx_buf[4] = bin2bcd(dt->tm_wday);	chip->txrx_buf[5] = bin2bcd(dt->tm_mday);	chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) |				((dt->tm_year > 99) ? 0x80 : 0x00);	chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100); 	/* do the i/o */	return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0);} static const struct rtc_class_ops ds1390_rtc_ops = {	.read_time	= ds1390_read_time,	.set_time	= ds1390_set_time,}; static int ds1390_probe(struct spi_device *spi){	unsigned char tmp;	struct ds1390 *chip;	int res; 	spi->mode = SPI_MODE_3;	spi->bits_per_word = 8;	spi_setup(spi); 	chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL);	if (!chip)		return -ENOMEM; 	spi_set_drvdata(spi, chip); 	res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);	if (res != 0) {		dev_err(&spi->dev, "unable to read device\n");		return res;	} 	if (spi->dev.of_node)		ds1390_trickle_of_init(spi); 	chip->rtc = devm_rtc_device_register(&spi->dev, "ds1390",					&ds1390_rtc_ops, THIS_MODULE);	if (IS_ERR(chip->rtc)) {		dev_err(&spi->dev, "unable to register device\n");		res = PTR_ERR(chip->rtc);	} 	return res;} static const struct of_device_id ds1390_of_match[] __maybe_unused = {	{ .compatible = "dallas,ds1390" },	{}};MODULE_DEVICE_TABLE(of, ds1390_of_match); static const struct spi_device_id ds1390_spi_ids[] = {	{ .name = "ds1390" },	{}};MODULE_DEVICE_TABLE(spi, ds1390_spi_ids); static struct spi_driver ds1390_driver = {	.driver = {		.name	= "rtc-ds1390",		.of_match_table = of_match_ptr(ds1390_of_match),	},	.probe	= ds1390_probe,	.id_table = ds1390_spi_ids,}; module_spi_driver(ds1390_driver); MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver");MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>");MODULE_LICENSE("GPL");MODULE_ALIAS("spi:rtc-ds1390");