/* * 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> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * 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, 8); 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[] = { { .compatible = "dallas,ds1390" }, {} }; MODULE_DEVICE_TABLE(of, ds1390_of_match); static struct spi_driver ds1390_driver = { .driver = { .name = "rtc-ds1390", .of_match_table = of_match_ptr(ds1390_of_match), }, .probe = ds1390_probe, }; 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");