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path: root/drivers/rtc/rtc-ds1672.c
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Diffstat (limited to 'drivers/rtc/rtc-ds1672.c')
-rw-r--r--drivers/rtc/rtc-ds1672.c160
1 files changed, 160 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1672.c b/drivers/rtc/rtc-ds1672.c
new file mode 100644
index 000000000..a3bb2cd9c
--- /dev/null
+++ b/drivers/rtc/rtc-ds1672.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * An rtc/i2c driver for the Dallas DS1672
+ * Copyright 2005-06 Tower Technologies
+ *
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ */
+
+#include <linux/i2c.h>
+#include <linux/rtc.h>
+#include <linux/module.h>
+
+/* Registers */
+
+#define DS1672_REG_CNT_BASE 0
+#define DS1672_REG_CONTROL 4
+#define DS1672_REG_TRICKLE 5
+
+#define DS1672_REG_CONTROL_EOSC 0x80
+
+/*
+ * In the routines that deal directly with the ds1672 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
+ * Time is set to UTC.
+ */
+static int ds1672_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ unsigned long time;
+ unsigned char addr = DS1672_REG_CONTROL;
+ unsigned char buf[4];
+
+ struct i2c_msg msgs[] = {
+ {/* setup read ptr */
+ .addr = client->addr,
+ .len = 1,
+ .buf = &addr
+ },
+ {/* read date */
+ .addr = client->addr,
+ .flags = I2C_M_RD,
+ .len = 1,
+ .buf = buf
+ },
+ };
+
+ /* read control register */
+ if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+ dev_warn(&client->dev, "Unable to read the control register\n");
+ return -EIO;
+ }
+
+ if (buf[0] & DS1672_REG_CONTROL_EOSC) {
+ dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n");
+ return -EINVAL;
+ }
+
+ addr = DS1672_REG_CNT_BASE;
+ msgs[1].len = 4;
+
+ /* read date registers */
+ if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+ dev_err(&client->dev, "%s: read error\n", __func__);
+ return -EIO;
+ }
+
+ dev_dbg(&client->dev,
+ "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
+ __func__, buf[0], buf[1], buf[2], buf[3]);
+
+ time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
+ (buf[1] << 8) | buf[0];
+
+ rtc_time64_to_tm(time, tm);
+
+ dev_dbg(&client->dev, "%s: tm is %ptR\n", __func__, tm);
+
+ return 0;
+}
+
+static int ds1672_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ int xfer;
+ unsigned char buf[6];
+ unsigned long secs = rtc_tm_to_time64(tm);
+
+ buf[0] = DS1672_REG_CNT_BASE;
+ buf[1] = secs & 0x000000FF;
+ buf[2] = (secs & 0x0000FF00) >> 8;
+ buf[3] = (secs & 0x00FF0000) >> 16;
+ buf[4] = (secs & 0xFF000000) >> 24;
+ buf[5] = 0; /* set control reg to enable counting */
+
+ xfer = i2c_master_send(client, buf, 6);
+ if (xfer != 6) {
+ dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static const struct rtc_class_ops ds1672_rtc_ops = {
+ .read_time = ds1672_read_time,
+ .set_time = ds1672_set_time,
+};
+
+static int ds1672_probe(struct i2c_client *client)
+{
+ int err = 0;
+ struct rtc_device *rtc;
+
+ dev_dbg(&client->dev, "%s\n", __func__);
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+ return -ENODEV;
+
+ rtc = devm_rtc_allocate_device(&client->dev);
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ rtc->ops = &ds1672_rtc_ops;
+ rtc->range_max = U32_MAX;
+
+ err = devm_rtc_register_device(rtc);
+ if (err)
+ return err;
+
+ i2c_set_clientdata(client, rtc);
+
+ return 0;
+}
+
+static const struct i2c_device_id ds1672_id[] = {
+ { "ds1672", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, ds1672_id);
+
+static const __maybe_unused struct of_device_id ds1672_of_match[] = {
+ { .compatible = "dallas,ds1672" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ds1672_of_match);
+
+static struct i2c_driver ds1672_driver = {
+ .driver = {
+ .name = "rtc-ds1672",
+ .of_match_table = of_match_ptr(ds1672_of_match),
+ },
+ .probe_new = ds1672_probe,
+ .id_table = ds1672_id,
+};
+
+module_i2c_driver(ds1672_driver);
+
+MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
+MODULE_LICENSE("GPL");