v4.19.13 snapshot.
diff --git a/drivers/rtc/rtc-max6902.c b/drivers/rtc/rtc-max6902.c
new file mode 100644
index 0000000..7458274
--- /dev/null
+++ b/drivers/rtc/rtc-max6902.c
@@ -0,0 +1,158 @@
+/* drivers/rtc/rtc-max6902.c
+ *
+ * Copyright (C) 2006 8D Technologies inc.
+ * Copyright (C) 2004 Compulab Ltd.
+ *
+ * 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.
+ *
+ * Driver for MAX6902 spi RTC
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+#include <linux/bcd.h>
+
+#define MAX6902_REG_SECONDS 0x01
+#define MAX6902_REG_MINUTES 0x03
+#define MAX6902_REG_HOURS 0x05
+#define MAX6902_REG_DATE 0x07
+#define MAX6902_REG_MONTH 0x09
+#define MAX6902_REG_DAY 0x0B
+#define MAX6902_REG_YEAR 0x0D
+#define MAX6902_REG_CONTROL 0x0F
+#define MAX6902_REG_CENTURY 0x13
+
+static int max6902_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 '0' to write */
+ buf[0] = address & 0x7f;
+ buf[1] = data;
+
+ return spi_write_then_read(spi, buf, 2, NULL, 0);
+}
+
+static int max6902_get_reg(struct device *dev, unsigned char address,
+ unsigned char *data)
+{
+ struct spi_device *spi = to_spi_device(dev);
+
+ /* Set MSB to indicate read */
+ *data = address | 0x80;
+
+ return spi_write_then_read(spi, data, 1, data, 1);
+}
+
+static int max6902_read_time(struct device *dev, struct rtc_time *dt)
+{
+ int err, century;
+ struct spi_device *spi = to_spi_device(dev);
+ unsigned char buf[8];
+
+ buf[0] = 0xbf; /* Burst read */
+
+ err = spi_write_then_read(spi, buf, 1, buf, 8);
+ if (err != 0)
+ return err;
+
+ /* The chip sends data in this order:
+ * Seconds, Minutes, Hours, Date, Month, Day, Year */
+ dt->tm_sec = bcd2bin(buf[0]);
+ dt->tm_min = bcd2bin(buf[1]);
+ dt->tm_hour = bcd2bin(buf[2]);
+ dt->tm_mday = bcd2bin(buf[3]);
+ dt->tm_mon = bcd2bin(buf[4]) - 1;
+ dt->tm_wday = bcd2bin(buf[5]);
+ dt->tm_year = bcd2bin(buf[6]);
+
+ /* Read century */
+ err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &buf[0]);
+ if (err != 0)
+ return err;
+
+ century = bcd2bin(buf[0]) * 100;
+
+ dt->tm_year += century;
+ dt->tm_year -= 1900;
+
+ return 0;
+}
+
+static int max6902_set_time(struct device *dev, struct rtc_time *dt)
+{
+ dt->tm_year = dt->tm_year + 1900;
+
+ /* Remove write protection */
+ max6902_set_reg(dev, MAX6902_REG_CONTROL, 0);
+
+ max6902_set_reg(dev, MAX6902_REG_SECONDS, bin2bcd(dt->tm_sec));
+ max6902_set_reg(dev, MAX6902_REG_MINUTES, bin2bcd(dt->tm_min));
+ max6902_set_reg(dev, MAX6902_REG_HOURS, bin2bcd(dt->tm_hour));
+
+ max6902_set_reg(dev, MAX6902_REG_DATE, bin2bcd(dt->tm_mday));
+ max6902_set_reg(dev, MAX6902_REG_MONTH, bin2bcd(dt->tm_mon + 1));
+ max6902_set_reg(dev, MAX6902_REG_DAY, bin2bcd(dt->tm_wday));
+ max6902_set_reg(dev, MAX6902_REG_YEAR, bin2bcd(dt->tm_year % 100));
+ max6902_set_reg(dev, MAX6902_REG_CENTURY, bin2bcd(dt->tm_year / 100));
+
+ /* Compulab used a delay here. However, the datasheet
+ * does not mention a delay being required anywhere... */
+ /* delay(2000); */
+
+ /* Write protect */
+ max6902_set_reg(dev, MAX6902_REG_CONTROL, 0x80);
+
+ return 0;
+}
+
+static const struct rtc_class_ops max6902_rtc_ops = {
+ .read_time = max6902_read_time,
+ .set_time = max6902_set_time,
+};
+
+static int max6902_probe(struct spi_device *spi)
+{
+ struct rtc_device *rtc;
+ unsigned char tmp;
+ int res;
+
+ spi->mode = SPI_MODE_3;
+ spi->bits_per_word = 8;
+ spi_setup(spi);
+
+ res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
+ if (res != 0)
+ return res;
+
+ rtc = devm_rtc_device_register(&spi->dev, "max6902",
+ &max6902_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ spi_set_drvdata(spi, rtc);
+ return 0;
+}
+
+static struct spi_driver max6902_driver = {
+ .driver = {
+ .name = "rtc-max6902",
+ },
+ .probe = max6902_probe,
+};
+
+module_spi_driver(max6902_driver);
+
+MODULE_DESCRIPTION("max6902 spi RTC driver");
+MODULE_AUTHOR("Raphael Assenat");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("spi:rtc-max6902");