iio: humidity: add support to hts221 rh/temp combo device

Add support to STM HTS221 humidity + temperature sensor

http://www.st.com/resource/en/datasheet/hts221.pdf

- continuous mode support
- i2c support
- spi support
- trigger mode support

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 125 insertions, 0 deletions

diff --git a/drivers/iio/humidity/hts221_spi.c b/drivers/iio/humidity/hts221_spi.c
new file mode 100644
index 000000000000..70df5e7150c1
--- /dev/null
+++ b/drivers/iio/humidity/hts221_spi.c
@@ -0,0 +1,125 @@
+/*
+ * STMicroelectronics hts221 spi driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi@st.com>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/slab.h>
+#include "hts221.h"
+
+#define SENSORS_SPI_READ	0x80
+#define SPI_AUTO_INCREMENT	0x40
+
+static int hts221_spi_read(struct device *dev, u8 addr, int len, u8 *data)
+{
+	int err;
+	struct spi_device *spi = to_spi_device(dev);
+	struct iio_dev *iio_dev = spi_get_drvdata(spi);
+	struct hts221_hw *hw = iio_priv(iio_dev);
+
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = hw->tb.tx_buf,
+			.bits_per_word = 8,
+			.len = 1,
+		},
+		{
+			.rx_buf = hw->tb.rx_buf,
+			.bits_per_word = 8,
+			.len = len,
+		}
+	};
+
+	if (len > 1)
+		addr |= SPI_AUTO_INCREMENT;
+	hw->tb.tx_buf[0] = addr | SENSORS_SPI_READ;
+
+	err = spi_sync_transfer(spi, xfers,  ARRAY_SIZE(xfers));
+	if (err < 0)
+		return err;
+
+	memcpy(data, hw->tb.rx_buf, len * sizeof(u8));
+
+	return len;
+}
+
+static int hts221_spi_write(struct device *dev, u8 addr, int len, u8 *data)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct iio_dev *iio_dev = spi_get_drvdata(spi);
+	struct hts221_hw *hw = iio_priv(iio_dev);
+
+	struct spi_transfer xfers = {
+		.tx_buf = hw->tb.tx_buf,
+		.bits_per_word = 8,
+		.len = len + 1,
+	};
+
+	if (len >= HTS221_TX_MAX_LENGTH)
+		return -ENOMEM;
+
+	if (len > 1)
+		addr |= SPI_AUTO_INCREMENT;
+	hw->tb.tx_buf[0] = addr;
+	memcpy(&hw->tb.tx_buf[1], data, len);
+
+	return spi_sync_transfer(spi, &xfers, 1);
+}
+
+static const struct hts221_transfer_function hts221_transfer_fn = {
+	.read = hts221_spi_read,
+	.write = hts221_spi_write,
+};
+
+static int hts221_spi_probe(struct spi_device *spi)
+{
+	struct hts221_hw *hw;
+	struct iio_dev *iio_dev;
+
+	iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*hw));
+	if (!iio_dev)
+		return -ENOMEM;
+
+	spi_set_drvdata(spi, iio_dev);
+
+	hw = iio_priv(iio_dev);
+	hw->name = spi->modalias;
+	hw->dev = &spi->dev;
+	hw->irq = spi->irq;
+	hw->tf = &hts221_transfer_fn;
+
+	return hts221_probe(iio_dev);
+}
+
+static const struct of_device_id hts221_spi_of_match[] = {
+	{ .compatible = "st,hts221", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, hts221_spi_of_match);
+
+static const struct spi_device_id hts221_spi_id_table[] = {
+	{ HTS221_DEV_NAME },
+	{},
+};
+MODULE_DEVICE_TABLE(spi, hts221_spi_id_table);
+
+static struct spi_driver hts221_driver = {
+	.driver = {
+		.name = "hts221_spi",
+		.of_match_table = of_match_ptr(hts221_spi_of_match),
+	},
+	.probe = hts221_spi_probe,
+	.id_table = hts221_spi_id_table,
+};
+module_spi_driver(hts221_driver);
+
+MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics hts221 spi driver");
+MODULE_LICENSE("GPL v2");