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>

drivers/iio/humidity/Kconfig

@@ -34,6 +34,28 @@ config HDC100X
 	  To compile this driver as a module, choose M here: the module
 	  will be called hdc100x.
 
+config HTS221
+	tristate "STMicroelectronics HTS221 sensor Driver"
+	depends on (I2C || SPI)
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	select HTS221_I2C if (I2C)
+	select HTS221_SPI if (SPI_MASTER)
+	help
+	  Say yes here to build support for STMicroelectronics HTS221
+	  temperature-humidity sensor
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called hts221.
+
+config HTS221_I2C
+	tristate
+	depends on HTS221
+
+config HTS221_SPI
+	tristate
+	depends on HTS221
+
 config HTU21
 	tristate "Measurement Specialties HTU21 humidity & temperature sensor"
 	depends on I2C

drivers/iio/humidity/Makefile

@@ -5,6 +5,13 @@
 obj-$(CONFIG_AM2315) += am2315.o
 obj-$(CONFIG_DHT11) += dht11.o
 obj-$(CONFIG_HDC100X) += hdc100x.o
+
+hts221-y := hts221_core.o \
+	    hts221_buffer.o
+obj-$(CONFIG_HTS221) += hts221.o
+obj-$(CONFIG_HTS221_I2C) += hts221_i2c.o
+obj-$(CONFIG_HTS221_SPI) += hts221_spi.o
+
 obj-$(CONFIG_HTU21) += htu21.o
 obj-$(CONFIG_SI7005) += si7005.o
 obj-$(CONFIG_SI7020) += si7020.o

drivers/iio/humidity/hts221.h

@@ -0,0 +1,73 @@
+/*
+ * STMicroelectronics hts221 sensor driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi@st.com>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#ifndef HTS221_H
+#define HTS221_H
+
+#define HTS221_DEV_NAME		"hts221"
+
+#include <linux/iio/iio.h>
+
+#define HTS221_RX_MAX_LENGTH	8
+#define HTS221_TX_MAX_LENGTH	8
+
+#define HTS221_DATA_SIZE	2
+
+struct hts221_transfer_buffer {
+	u8 rx_buf[HTS221_RX_MAX_LENGTH];
+	u8 tx_buf[HTS221_TX_MAX_LENGTH] ____cacheline_aligned;
+};
+
+struct hts221_transfer_function {
+	int (*read)(struct device *dev, u8 addr, int len, u8 *data);
+	int (*write)(struct device *dev, u8 addr, int len, u8 *data);
+};
+
+#define HTS221_AVG_DEPTH	8
+struct hts221_avg_avl {
+	u16 avg;
+	u8 val;
+};
+
+enum hts221_sensor_type {
+	HTS221_SENSOR_H,
+	HTS221_SENSOR_T,
+	HTS221_SENSOR_MAX,
+};
+
+struct hts221_sensor {
+	u8 cur_avg_idx;
+	int slope, b_gen;
+};
+
+struct hts221_hw {
+	const char *name;
+	struct device *dev;
+
+	struct mutex lock;
+	struct iio_trigger *trig;
+	int irq;
+
+	struct hts221_sensor sensors[HTS221_SENSOR_MAX];
+
+	u8 odr;
+
+	const struct hts221_transfer_function *tf;
+	struct hts221_transfer_buffer tb;
+};
+
+int hts221_config_drdy(struct hts221_hw *hw, bool enable);
+int hts221_probe(struct iio_dev *iio_dev);
+int hts221_power_on(struct hts221_hw *hw);
+int hts221_power_off(struct hts221_hw *hw);
+int hts221_allocate_buffers(struct hts221_hw *hw);
+int hts221_allocate_trigger(struct hts221_hw *hw);
+
+#endif /* HTS221_H */

drivers/iio/humidity/hts221_buffer.c

@@ -0,0 +1,169 @@
+/*
+ * STMicroelectronics hts221 sensor 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/device.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+#include <linux/interrupt.h>
+#include <linux/iio/events.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/buffer.h>
+
+#include "hts221.h"
+
+#define HTS221_REG_STATUS_ADDR		0x27
+#define HTS221_RH_DRDY_MASK		BIT(1)
+#define HTS221_TEMP_DRDY_MASK		BIT(0)
+
+static int hts221_trig_set_state(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *iio_dev = iio_trigger_get_drvdata(trig);
+	struct hts221_hw *hw = iio_priv(iio_dev);
+
+	return hts221_config_drdy(hw, state);
+}
+
+static const struct iio_trigger_ops hts221_trigger_ops = {
+	.owner = THIS_MODULE,
+	.set_trigger_state = hts221_trig_set_state,
+};
+
+static irqreturn_t hts221_trigger_handler_thread(int irq, void *private)
+{
+	struct hts221_hw *hw = (struct hts221_hw *)private;
+	u8 status;
+	int err;
+
+	err = hw->tf->read(hw->dev, HTS221_REG_STATUS_ADDR, sizeof(status),
+			   &status);
+	if (err < 0)
+		return IRQ_HANDLED;
+
+	/* 
+	 * H_DA bit (humidity data available) is routed to DRDY line.
+	 * Humidity sample is computed after temperature one.
+	 * Here we can assume data channels are both available if H_DA bit
+	 * is set in status register
+	 */
+	if (!(status & HTS221_RH_DRDY_MASK))
+		return IRQ_NONE;
+
+	iio_trigger_poll_chained(hw->trig);
+
+	return IRQ_HANDLED;
+}
+
+int hts221_allocate_trigger(struct hts221_hw *hw)
+{
+	struct iio_dev *iio_dev = iio_priv_to_dev(hw);
+	unsigned long irq_type;
+	int err;
+
+	irq_type = irqd_get_trigger_type(irq_get_irq_data(hw->irq));
+
+	switch (irq_type) {
+	case IRQF_TRIGGER_HIGH:
+	case IRQF_TRIGGER_RISING:
+		break;
+	default:
+		dev_info(hw->dev,
+			 "mode %lx unsupported, using IRQF_TRIGGER_RISING\n",
+			 irq_type);
+		irq_type = IRQF_TRIGGER_RISING;
+		break;
+	}
+
+	err = devm_request_threaded_irq(hw->dev, hw->irq, NULL,
+					hts221_trigger_handler_thread,
+					irq_type | IRQF_ONESHOT,
+					hw->name, hw);
+	if (err) {
+		dev_err(hw->dev, "failed to request trigger irq %d\n",
+			hw->irq);
+		return err;
+	}
+
+	hw->trig = devm_iio_trigger_alloc(hw->dev, "%s-trigger",
+					  iio_dev->name);
+	if (!hw->trig)
+		return -ENOMEM;
+
+	iio_trigger_set_drvdata(hw->trig, iio_dev);
+	hw->trig->ops = &hts221_trigger_ops;
+	hw->trig->dev.parent = hw->dev;
+	iio_dev->trig = iio_trigger_get(hw->trig);
+
+	return devm_iio_trigger_register(hw->dev, hw->trig);
+}
+
+static int hts221_buffer_preenable(struct iio_dev *iio_dev)
+{
+	return hts221_power_on(iio_priv(iio_dev));
+}
+
+static int hts221_buffer_postdisable(struct iio_dev *iio_dev)
+{
+	return hts221_power_off(iio_priv(iio_dev));
+}
+
+static const struct iio_buffer_setup_ops hts221_buffer_ops = {
+	.preenable = hts221_buffer_preenable,
+	.postenable = iio_triggered_buffer_postenable,
+	.predisable = iio_triggered_buffer_predisable,
+	.postdisable = hts221_buffer_postdisable,
+};
+
+static irqreturn_t hts221_buffer_handler_thread(int irq, void *p)
+{
+	u8 buffer[ALIGN(2 * HTS221_DATA_SIZE, sizeof(s64)) + sizeof(s64)];
+	struct iio_poll_func *pf = p;
+	struct iio_dev *iio_dev = pf->indio_dev;
+	struct hts221_hw *hw = iio_priv(iio_dev);
+	struct iio_chan_spec const *ch;
+	int err;
+
+	/* humidity data */
+	ch = &iio_dev->channels[HTS221_SENSOR_H];
+	err = hw->tf->read(hw->dev, ch->address, HTS221_DATA_SIZE,
+			   buffer);
+	if (err < 0)
+		goto out;
+
+	/* temperature data */
+	ch = &iio_dev->channels[HTS221_SENSOR_T];
+	err = hw->tf->read(hw->dev, ch->address, HTS221_DATA_SIZE,
+			   buffer + HTS221_DATA_SIZE);
+	if (err < 0)
+		goto out;
+
+	iio_push_to_buffers_with_timestamp(iio_dev, buffer,
+					   iio_get_time_ns(iio_dev));
+
+out:
+	iio_trigger_notify_done(hw->trig);
+
+	return IRQ_HANDLED;
+}
+
+int hts221_allocate_buffers(struct hts221_hw *hw)
+{
+	return devm_iio_triggered_buffer_setup(hw->dev, iio_priv_to_dev(hw),
+					NULL, hts221_buffer_handler_thread,
+					&hts221_buffer_ops);
+}
+
+MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics hts221 buffer driver");
+MODULE_LICENSE("GPL v2");