1 files changed, 124 insertions, 0 deletions
diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c
new file mode 100644
index 000000000..61f373fab
--- /dev/null
+++ b/drivers/iio/adc/ltc2497.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
+ *
+ * Copyright (C) 2017 Analog Devices Inc.
+ *
+ * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
+ */
+
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+
+#include "ltc2497.h"
+
+struct ltc2497_driverdata {
+	/* this must be the first member */
+	struct ltc2497core_driverdata common_ddata;
+	struct i2c_client *client;
+	/*
+	 * DMA (thus cache coherency maintenance) requires the
+	 * transfer buffers to live in their own cache lines.
+	 */
+	__be32 buf ____cacheline_aligned;
+};
+
+static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
+				      u8 address, int *val)
+{
+	struct ltc2497_driverdata *st =
+		container_of(ddata, struct ltc2497_driverdata, common_ddata);
+	int ret;
+
+	if (val) {
+		ret = i2c_master_recv(st->client, (char *)&st->buf, 3);
+		if (ret < 0) {
+			dev_err(&st->client->dev, "i2c_master_recv failed\n");
+			return ret;
+		}
+
+		*val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
+
+		/*
+		 * The part started a new conversion at the end of the above i2c
+		 * transfer, so if the address didn't change since the last call
+		 * everything is fine and we can return early.
+		 * If not (which should only happen when some sort of bulk
+		 * conversion is implemented) we have to program the new
+		 * address. Note that this probably fails as the conversion that
+		 * was triggered above is like not complete yet and the two
+		 * operations have to be done in a single transfer.
+		 */
+		if (ddata->addr_prev == address)
+			return 0;
+	}
+
+	ret = i2c_smbus_write_byte(st->client,
+				   LTC2497_ENABLE | address);
+	if (ret)
+		dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
+			ERR_PTR(ret));
+	return ret;
+}
+
+static int ltc2497_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct ltc2497_driverdata *st;
+	struct device *dev = &client->dev;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+				     I2C_FUNC_SMBUS_WRITE_BYTE))
+		return -EOPNOTSUPP;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	st->client = client;
+	st->common_ddata.result_and_measure = ltc2497_result_and_measure;
+
+	return ltc2497core_probe(dev, indio_dev);
+}
+
+static int ltc2497_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	ltc2497core_remove(indio_dev);
+
+	return 0;
+}
+
+static const struct i2c_device_id ltc2497_id[] = {
+	{ "ltc2497", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ltc2497_id);
+
+static const struct of_device_id ltc2497_of_match[] = {
+	{ .compatible = "lltc,ltc2497", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ltc2497_of_match);
+
+static struct i2c_driver ltc2497_driver = {
+	.driver = {
+		.name = "ltc2497",
+		.of_match_table = ltc2497_of_match,
+	},
+	.probe = ltc2497_probe,
+	.remove = ltc2497_remove,
+	.id_table = ltc2497_id,
+};
+module_i2c_driver(ltc2497_driver);
+
+MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
+MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
+MODULE_LICENSE("GPL v2");