--- /dev/null
+/*
+ * 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>
+
+#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
+
+struct ds1390 {
+ struct rtc_device *rtc;
+ u8 txrx_buf[9]; /* cmd + 8 registers */
+};
+
+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[1];
+
+ return 0;
+}
+
+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 rtc_valid_tm(dt);
+}
+
+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;
+ }
+
+ 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 struct spi_driver ds1390_driver = {
+ .driver = {
+ .name = "rtc-ds1390",
+ .owner = THIS_MODULE,
+ },
+ .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");
Code Review / kvmfornfv.git / blobdiff