diff options
Diffstat (limited to 'drivers/rtc/rtc-ds1390.c')
| -rw-r--r-- | drivers/rtc/rtc-ds1390.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1390.c b/drivers/rtc/rtc-ds1390.c new file mode 100644 index 000000000..66fc8617d --- /dev/null +++ b/drivers/rtc/rtc-ds1390.c @@ -0,0 +1,235 @@ +// 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, 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"); |