[PATCH v3 0/2] add support to STM HTS221 humidity + temperature sensor

[PATCH v3 0/2] add support to STM HTS221 humidity + temperature sensor

[Lorenzo Bianconi]

Changes since v2:
- fix endianness issue in hts221_parse_caldata()
- make dev->buffer large enough to avoid the memcpy() in
  hts221_buffer_handler_thread()
- remove trigger top half routine and move timestamp sampling in
  hts221_buffer_handler_thread()
- use devm_iio_* routines to register iio_device/trigger and setup
  iio_triggered_buffer
- reduce spi max read/write size
- cosmetics

Changes since v1:
- use single iio_device for both humidity and temperature sensors
- use iio_claim_direct_mode() routine instead of grabbing the mutex directly
- use more unique prefix for all defines
- remove useless dev_info()
- use of_match_ptr instead of access directly to of_match_table
- use devm_iio_* routines
- use info_mask_shared_by_all element for sampling_frequency
- use oversampling ABI for humidityrelative_avg_sample and temp_avg_sample

Lorenzo Bianconi (2):
  iio: humidity: add support to hts221 rh/temp combo device
  Documentation: dt: iio: humidity: add hts221 sensor device binding

 .../devicetree/bindings/iio/humidity/hts221.txt    |  19 +
 drivers/iio/humidity/Kconfig                       |   2 +
 drivers/iio/humidity/Makefile                      |   1 +
 drivers/iio/humidity/hts221/Kconfig                |  23 +
 drivers/iio/humidity/hts221/Makefile               |   6 +
 drivers/iio/humidity/hts221/hts221.h               |  78 +++
 drivers/iio/humidity/hts221/hts221_buffer.c        | 168 +++++
 drivers/iio/humidity/hts221/hts221_core.c          | 684 +++++++++++++++++++++
 drivers/iio/humidity/hts221/hts221_i2c.c           | 110 ++++
 drivers/iio/humidity/hts221/hts221_spi.c           | 125 ++++
 10 files changed, 1216 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/humidity/hts221.txt
 create mode 100644 drivers/iio/humidity/hts221/Kconfig
 create mode 100644 drivers/iio/humidity/hts221/Makefile
 create mode 100644 drivers/iio/humidity/hts221/hts221.h
 create mode 100644 drivers/iio/humidity/hts221/hts221_buffer.c
 create mode 100644 drivers/iio/humidity/hts221/hts221_core.c
 create mode 100644 drivers/iio/humidity/hts221/hts221_i2c.c
 create mode 100644 drivers/iio/humidity/hts221/hts221_spi.c

-- 
2.7.4

--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH v3 1/2] iio: humidity: add support to hts221 rh/temp combo device

[Lorenzo Bianconi]

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-qxv4g6HH51o@public.gmane.org>
---
 drivers/iio/humidity/Kconfig                |   2 +
 drivers/iio/humidity/Makefile               |   1 +
 drivers/iio/humidity/hts221/Kconfig         |  23 +
 drivers/iio/humidity/hts221/Makefile        |   6 +
 drivers/iio/humidity/hts221/hts221.h        |  78 ++++
 drivers/iio/humidity/hts221/hts221_buffer.c | 168 +++++++
 drivers/iio/humidity/hts221/hts221_core.c   | 684 ++++++++++++++++++++++++++++
 drivers/iio/humidity/hts221/hts221_i2c.c    | 110 +++++
 drivers/iio/humidity/hts221/hts221_spi.c    | 125 +++++
 9 files changed, 1197 insertions(+)
 create mode 100644 drivers/iio/humidity/hts221/Kconfig
 create mode 100644 drivers/iio/humidity/hts221/Makefile
 create mode 100644 drivers/iio/humidity/hts221/hts221.h
 create mode 100644 drivers/iio/humidity/hts221/hts221_buffer.c
 create mode 100644 drivers/iio/humidity/hts221/hts221_core.c
 create mode 100644 drivers/iio/humidity/hts221/hts221_i2c.c
 create mode 100644 drivers/iio/humidity/hts221/hts221_spi.c

diff --git a/drivers/iio/humidity/Kconfig b/drivers/iio/humidity/Kconfig
index b17e2e2..4ce75da 100644
--- a/drivers/iio/humidity/Kconfig
+++ b/drivers/iio/humidity/Kconfig
@@ -69,4 +69,6 @@ config SI7020
 	  To compile this driver as a module, choose M here: the module
 	  will be called si7020.
 
+source "drivers/iio/humidity/hts221/Kconfig"
+
 endmenu
diff --git a/drivers/iio/humidity/Makefile b/drivers/iio/humidity/Makefile
index 4a73442..25e11f3 100644
--- a/drivers/iio/humidity/Makefile
+++ b/drivers/iio/humidity/Makefile
@@ -5,6 +5,7 @@
 obj-$(CONFIG_AM2315) += am2315.o
 obj-$(CONFIG_DHT11) += dht11.o
 obj-$(CONFIG_HDC100X) += hdc100x.o
+obj-$(CONFIG_HTS221) += hts221/
 obj-$(CONFIG_HTU21) += htu21.o
 obj-$(CONFIG_SI7005) += si7005.o
 obj-$(CONFIG_SI7020) += si7020.o
diff --git a/drivers/iio/humidity/hts221/Kconfig b/drivers/iio/humidity/hts221/Kconfig
new file mode 100644
index 0000000..c10013d
--- /dev/null
+++ b/drivers/iio/humidity/hts221/Kconfig
@@ -0,0 +1,23 @@
+
+config HTS221
+	tristate "STMicroelectronics HTS221 sensor Driver"
+	depends on (I2C || SPI)
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	select HTS221_I2C if (I2C)
+	select HTS221_SPI if (SPI_MASTER)
+	help
+	  Say yes here to build support for STMicroelectronics HTS221
+	  temperature-humidity sensor
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called hts221.
+
+config HTS221_I2C
+	tristate
+	depends on HTS221
+
+config HTS221_SPI
+	tristate
+	depends on HTS221
+
diff --git a/drivers/iio/humidity/hts221/Makefile b/drivers/iio/humidity/hts221/Makefile
new file mode 100644
index 0000000..e1f5464
--- /dev/null
+++ b/drivers/iio/humidity/hts221/Makefile
@@ -0,0 +1,6 @@
+hts221-y := hts221_core.o \
+	    hts221_buffer.o
+
+obj-$(CONFIG_HTS221) += hts221.o
+obj-$(CONFIG_HTS221_I2C) += hts221_i2c.o
+obj-$(CONFIG_HTS221_SPI) += hts221_spi.o
diff --git a/drivers/iio/humidity/hts221/hts221.h b/drivers/iio/humidity/hts221/hts221.h
new file mode 100644
index 0000000..6e06e6a
--- /dev/null
+++ b/drivers/iio/humidity/hts221/hts221.h
@@ -0,0 +1,78 @@
+/*
+ * STMicroelectronics hts221 sensor driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
+ *
+ * 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 {
+	struct hts221_dev *dev;
+
+	enum hts221_sensor_type type;
+	u8 cur_avg_idx;
+	int slope, b_gen;
+};
+
+struct hts221_dev {
+	const char *name;
+	struct device *dev;
+
+	struct mutex lock;
+
+	u8 buffer[ALIGN(2 * HTS221_DATA_SIZE, sizeof(s64)) + sizeof(s64)];
+	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_dev *dev, bool enable);
+int hts221_probe(struct hts221_dev *dev);
+int hts221_dev_power_on(struct hts221_dev *dev);
+int hts221_dev_power_off(struct hts221_dev *dev);
+int hts221_allocate_buffers(struct hts221_dev *dev);
+int hts221_allocate_triggers(struct hts221_dev *dev);
+
+#endif /* HTS221_H */
diff --git a/drivers/iio/humidity/hts221/hts221_buffer.c b/drivers/iio/humidity/hts221/hts221_buffer.c
new file mode 100644
index 0000000..69330b7
--- /dev/null
+++ b/drivers/iio/humidity/hts221/hts221_buffer.c
@@ -0,0 +1,168 @@
+/*
+ * STMicroelectronics hts221 sensor driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
+ *
+ * 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_dev *dev = iio_priv(iio_dev);
+
+	return hts221_config_drdy(dev, 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_dev *dev = (struct hts221_dev *)private;
+	struct iio_dev *iio_dev = iio_priv_to_dev(dev);
+	struct iio_chan_spec const *ch;
+	int err, count = 0;
+	u8 status;
+
+	err = dev->tf->read(dev->dev, HTS221_REG_STATUS_ADDR, sizeof(status),
+			    &status);
+	if (err < 0)
+		return IRQ_HANDLED;
+
+	/* humidity data */
+	if (status & HTS221_RH_DRDY_MASK) {
+		ch = &iio_dev->channels[HTS221_SENSOR_H];
+		err = dev->tf->read(dev->dev, ch->address, HTS221_DATA_SIZE,
+				    dev->buffer);
+		if (err < 0)
+			return IRQ_HANDLED;
+
+		count++;
+	}
+
+	/* temperature data */
+	if (status & HTS221_TEMP_DRDY_MASK) {
+		ch = &iio_dev->channels[HTS221_SENSOR_T];
+		err = dev->tf->read(dev->dev, ch->address, HTS221_DATA_SIZE,
+				    dev->buffer + 2 * count);
+		if (err < 0)
+			return IRQ_HANDLED;
+
+		count++;
+	}
+
+	if (count > 0) {
+		iio_trigger_poll_chained(dev->trig);
+		return IRQ_HANDLED;
+	} else {
+		return IRQ_NONE;
+	}
+}
+
+int hts221_allocate_triggers(struct hts221_dev *dev)
+{
+	struct iio_dev *iio_dev = iio_priv_to_dev(dev);
+	unsigned long irq_type;
+	int err;
+
+	irq_type = irqd_get_trigger_type(irq_get_irq_data(dev->irq));
+
+	switch (irq_type) {
+	case IRQF_TRIGGER_HIGH:
+	case IRQF_TRIGGER_RISING:
+		break;
+	default:
+		dev_info(dev->dev,
+			 "mode %lx unsupported, using IRQF_TRIGGER_RISING\n",
+			 irq_type);
+		irq_type = IRQF_TRIGGER_RISING;
+		break;
+	}
+
+	err = devm_request_threaded_irq(dev->dev, dev->irq, NULL,
+					hts221_trigger_handler_thread,
+					irq_type | IRQF_ONESHOT,
+					dev->name, dev);
+	if (err) {
+		dev_err(dev->dev, "failed to request trigger irq %d\n",
+			dev->irq);
+		return err;
+	}
+
+	dev->trig = devm_iio_trigger_alloc(dev->dev, "%s-trigger",
+					   iio_dev->name);
+	if (!dev->trig)
+		return -ENOMEM;
+
+	iio_trigger_set_drvdata(dev->trig, iio_dev);
+	dev->trig->ops = &hts221_trigger_ops;
+	dev->trig->dev.parent = dev->dev;
+	iio_dev->trig = iio_trigger_get(dev->trig);
+
+	return devm_iio_trigger_register(dev->dev, dev->trig);
+}
+
+static int hts221_buffer_preenable(struct iio_dev *iio_dev)
+{
+	return hts221_dev_power_on(iio_priv(iio_dev));
+}
+
+static int hts221_buffer_postdisable(struct iio_dev *iio_dev)
+{
+	return hts221_dev_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)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *iio_dev = pf->indio_dev;
+	struct hts221_dev *dev = iio_priv(iio_dev);
+
+	iio_push_to_buffers_with_timestamp(iio_dev, dev->buffer,
+					   iio_get_time_ns(iio_dev));
+	iio_trigger_notify_done(dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+int hts221_allocate_buffers(struct hts221_dev *dev)
+{
+	return devm_iio_triggered_buffer_setup(dev->dev, iio_priv_to_dev(dev),
+					NULL, hts221_buffer_handler_thread,
+					&hts221_buffer_ops);
+}
+
+MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>");
+MODULE_DESCRIPTION("STMicroelectronics hts221 buffer driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/humidity/hts221/hts221_core.c b/drivers/iio/humidity/hts221/hts221_core.c
new file mode 100644
index 0000000..a537798
--- /dev/null
+++ b/drivers/iio/humidity/hts221/hts221_core.c
@@ -0,0 +1,684 @@
+/*
+ * STMicroelectronics hts221 sensor driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/iio/sysfs.h>
+#include <linux/delay.h>
+#include <asm/unaligned.h>
+
+#include "hts221.h"
+
+#define HTS221_REG_WHOAMI_ADDR		0x0f
+#define HTS221_REG_WHOAMI_VAL		0xbc
+
+#define HTS221_REG_CNTRL1_ADDR		0x20
+#define HTS221_REG_CNTRL2_ADDR		0x21
+#define HTS221_REG_CNTRL3_ADDR		0x22
+
+#define HTS221_REG_AVG_ADDR		0x10
+#define HTS221_REG_H_OUT_L		0x28
+#define HTS221_REG_T_OUT_L		0x2a
+
+#define HTS221_HUMIDITY_AVG_MASK	0x07
+#define HTS221_TEMP_AVG_MASK		0x38
+
+#define HTS221_ODR_MASK			0x87
+#define HTS221_BDU_MASK			BIT(2)
+
+#define HTS221_DRDY_MASK		BIT(2)
+
+#define HTS221_ENABLE_SENSOR		BIT(7)
+
+#define HTS221_HUMIDITY_AVG_4		0x00 /* 0.4 %RH */
+#define HTS221_HUMIDITY_AVG_8		0x01 /* 0.3 %RH */
+#define HTS221_HUMIDITY_AVG_16		0x02 /* 0.2 %RH */
+#define HTS221_HUMIDITY_AVG_32		0x03 /* 0.15 %RH */
+#define HTS221_HUMIDITY_AVG_64		0x04 /* 0.1 %RH */
+#define HTS221_HUMIDITY_AVG_128		0x05 /* 0.07 %RH */
+#define HTS221_HUMIDITY_AVG_256		0x06 /* 0.05 %RH */
+#define HTS221_HUMIDITY_AVG_512		0x07 /* 0.03 %RH */
+
+#define HTS221_TEMP_AVG_2		0x00 /* 0.08 degC */
+#define HTS221_TEMP_AVG_4		0x08 /* 0.05 degC */
+#define HTS221_TEMP_AVG_8		0x10 /* 0.04 degC */
+#define HTS221_TEMP_AVG_16		0x18 /* 0.03 degC */
+#define HTS221_TEMP_AVG_32		0x20 /* 0.02 degC */
+#define HTS221_TEMP_AVG_64		0x28 /* 0.015 degC */
+#define HTS221_TEMP_AVG_128		0x30 /* 0.01 degC */
+#define HTS221_TEMP_AVG_256		0x38 /* 0.007 degC */
+
+/* calibration registers */
+#define HTS221_REG_0RH_CAL_X_H		0x36
+#define HTS221_REG_1RH_CAL_X_H		0x3a
+#define HTS221_REG_0RH_CAL_Y_H		0x30
+#define HTS221_REG_1RH_CAL_Y_H		0x31
+#define HTS221_REG_0T_CAL_X_L		0x3c
+#define HTS221_REG_1T_CAL_X_L		0x3e
+#define HTS221_REG_0T_CAL_Y_H		0x32
+#define HTS221_REG_1T_CAL_Y_H		0x33
+#define HTS221_REG_T1_T0_CAL_Y_H	0x35
+
+struct hts221_odr {
+	u8 hz;
+	u8 val;
+};
+
+struct hts221_avg {
+	u8 addr;
+	u8 mask;
+	struct hts221_avg_avl avg_avl[HTS221_AVG_DEPTH];
+};
+
+static const struct hts221_odr hts221_odr_table[] = {
+	{ 1, 0x01 },	/* 1Hz */
+	{ 7, 0x02 },	/* 7Hz */
+	{ 13, 0x03 },	/* 12.5Hz */
+};
+
+static const struct hts221_avg hts221_avg_list[] = {
+	{
+		.addr = HTS221_REG_AVG_ADDR,
+		.mask = HTS221_HUMIDITY_AVG_MASK,
+		.avg_avl = {
+			{ 4, HTS221_HUMIDITY_AVG_4 },
+			{ 8, HTS221_HUMIDITY_AVG_8 },
+			{ 16, HTS221_HUMIDITY_AVG_16 },
+			{ 32, HTS221_HUMIDITY_AVG_32 },
+			{ 64, HTS221_HUMIDITY_AVG_64 },
+			{ 128, HTS221_HUMIDITY_AVG_128 },
+			{ 256, HTS221_HUMIDITY_AVG_256 },
+			{ 512, HTS221_HUMIDITY_AVG_512 },
+		},
+	},
+	{
+		.addr = HTS221_REG_AVG_ADDR,
+		.mask = HTS221_TEMP_AVG_MASK,
+		.avg_avl = {
+			{ 2, HTS221_TEMP_AVG_2 },
+			{ 4, HTS221_TEMP_AVG_4 },
+			{ 8, HTS221_TEMP_AVG_8 },
+			{ 16, HTS221_TEMP_AVG_16 },
+			{ 32, HTS221_TEMP_AVG_32 },
+			{ 64, HTS221_TEMP_AVG_64 },
+			{ 128, HTS221_TEMP_AVG_128 },
+			{ 256, HTS221_TEMP_AVG_256 },
+		},
+	},
+};
+
+static const struct iio_chan_spec hts221_channels[] = {
+	{
+		.type = IIO_HUMIDITYRELATIVE,
+		.address = HTS221_REG_H_OUT_L,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_OFFSET) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_LE,
+		},
+	},
+	{
+		.type = IIO_TEMP,
+		.address = HTS221_REG_T_OUT_L,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_OFFSET) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_LE,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(2),
+};
+
+static int hts221_write_with_mask(struct hts221_dev *dev, u8 addr, u8 mask,
+				  u8 val)
+{
+	u8 data;
+	int err;
+
+	mutex_lock(&dev->lock);
+
+	err = dev->tf->read(dev->dev, addr, sizeof(data), &data);
+	if (err < 0) {
+		dev_err(dev->dev, "failed to read %02x register\n", addr);
+		mutex_unlock(&dev->lock);
+
+		return err;
+	}
+
+	data = (data & ~mask) | (val & mask);
+
+	err = dev->tf->write(dev->dev, addr, sizeof(data), &data);
+	if (err < 0) {
+		dev_err(dev->dev, "failed to write %02x register\n", addr);
+		mutex_unlock(&dev->lock);
+
+		return err;
+	}
+
+	mutex_unlock(&dev->lock);
+
+	return 0;
+}
+
+static int hts221_check_whoami(struct hts221_dev *dev)
+{
+	u8 data;
+	int err;
+
+	err = dev->tf->read(dev->dev, HTS221_REG_WHOAMI_ADDR, sizeof(data),
+			    &data);
+	if (err < 0) {
+		dev_err(dev->dev, "failed to read whoami register\n");
+		return err;
+	}
+
+	if (data != HTS221_REG_WHOAMI_VAL) {
+		dev_err(dev->dev, "wrong whoami {%02x vs %02x}\n",
+			data, HTS221_REG_WHOAMI_VAL);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+int hts221_config_drdy(struct hts221_dev *dev, bool enable)
+{
+	u8 val = enable ? BIT(2) : 0;
+
+	return hts221_write_with_mask(dev, HTS221_REG_CNTRL3_ADDR,
+				      HTS221_DRDY_MASK, val);
+}
+
+static int hts221_update_odr(struct hts221_dev *dev, u8 odr)
+{
+	int i, err;
+	u8 val;
+
+	for (i = 0; i < ARRAY_SIZE(hts221_odr_table); i++)
+		if (hts221_odr_table[i].hz == odr)
+			break;
+
+	if (i == ARRAY_SIZE(hts221_odr_table))
+		return -EINVAL;
+
+	val = HTS221_ENABLE_SENSOR | HTS221_BDU_MASK | hts221_odr_table[i].val;
+	err = hts221_write_with_mask(dev, HTS221_REG_CNTRL1_ADDR,
+				     HTS221_ODR_MASK, val);
+	if (err < 0)
+		return err;
+
+	dev->odr = odr;
+
+	return 0;
+}
+
+static int hts221_update_avg(struct hts221_sensor *sensor, u16 val)
+{
+	int i, err;
+	const struct hts221_avg *avg = &hts221_avg_list[sensor->type];
+
+	for (i = 0; i < HTS221_AVG_DEPTH; i++)
+		if (avg->avg_avl[i].avg == val)
+			break;
+
+	if (i == HTS221_AVG_DEPTH)
+		return -EINVAL;
+
+	err = hts221_write_with_mask(sensor->dev, avg->addr, avg->mask,
+				     avg->avg_avl[i].val);
+	if (err < 0)
+		return err;
+
+	sensor->cur_avg_idx = i;
+
+	return 0;
+}
+
+static ssize_t hts221_sysfs_sampling_freq(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	int i;
+	ssize_t len = 0;
+
+	for (i = 0; i < ARRAY_SIZE(hts221_odr_table); i++)
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
+				 hts221_odr_table[i].hz);
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static ssize_t
+hts221_sysfs_rh_oversampling_avail(struct device *dev,
+				   struct device_attribute *attr,
+				   char *buf)
+{
+	const struct hts221_avg *avg = &hts221_avg_list[HTS221_SENSOR_H];
+	ssize_t len = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(avg->avg_avl); i++)
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
+				 avg->avg_avl[i].avg);
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static ssize_t
+hts221_sysfs_temp_oversampling_avail(struct device *dev,
+				     struct device_attribute *attr,
+				     char *buf)
+{
+	const struct hts221_avg *avg = &hts221_avg_list[HTS221_SENSOR_T];
+	ssize_t len = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(avg->avg_avl); i++)
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
+				 avg->avg_avl[i].avg);
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+int hts221_dev_power_on(struct hts221_dev *dev)
+{
+	struct hts221_sensor *sensor;
+	int i, err, val;
+
+	for (i = 0; i < HTS221_SENSOR_MAX; i++) {
+		sensor = &dev->sensors[i];
+		val = hts221_avg_list[i].avg_avl[sensor->cur_avg_idx].avg;
+
+		err = hts221_update_avg(sensor, val);
+		if (err < 0)
+			return err;
+	}
+
+	err = hts221_update_odr(dev, dev->odr);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+int hts221_dev_power_off(struct hts221_dev *dev)
+{
+	u8 data[] = {0x00, 0x00};
+
+	return dev->tf->write(dev->dev, HTS221_REG_CNTRL1_ADDR, sizeof(data),
+			      data);
+}
+
+static int hts221_parse_caldata(struct hts221_sensor *sensor)
+{
+	int err, *slope, *b_gen;
+	u8 addr_x0, addr_x1;
+	s16 cal_x0, cal_x1, cal_y0, cal_y1;
+	struct hts221_dev *dev = sensor->dev;
+
+	switch (sensor->type) {
+	case HTS221_SENSOR_H: {
+		u8 data;
+
+		addr_x0 = HTS221_REG_0RH_CAL_X_H;
+		addr_x1 = HTS221_REG_1RH_CAL_X_H;
+		cal_y1 = 0;
+		cal_y0 = 0;
+
+		err = dev->tf->read(dev->dev, HTS221_REG_0RH_CAL_Y_H,
+				    sizeof(data), &data);
+		if (err < 0)
+			return err;
+		cal_y0 = data;
+
+		err = dev->tf->read(dev->dev, HTS221_REG_1RH_CAL_Y_H,
+				    sizeof(data), &data);
+		if (err < 0)
+			return err;
+		cal_y1 = data;
+
+		break;
+	}
+	case HTS221_SENSOR_T: {
+		u8 cal0, cal1;
+
+		addr_x0 = HTS221_REG_0T_CAL_X_L;
+		addr_x1 = HTS221_REG_1T_CAL_X_L;
+
+		err = dev->tf->read(dev->dev, HTS221_REG_0T_CAL_Y_H,
+				    sizeof(cal0), &cal0);
+		if (err < 0)
+			return err;
+
+		err = dev->tf->read(dev->dev, HTS221_REG_T1_T0_CAL_Y_H,
+				    sizeof(cal1), &cal1);
+		if (err < 0)
+			return err;
+		cal_y0 = (le16_to_cpu(cal1 & 0x3) << 8) | cal0;
+
+		err = dev->tf->read(dev->dev, HTS221_REG_1T_CAL_Y_H,
+				    sizeof(cal0), &cal0);
+		if (err < 0)
+			return err;
+
+		err = dev->tf->read(dev->dev, HTS221_REG_T1_T0_CAL_Y_H,
+				    sizeof(cal1), &cal1);
+		if (err < 0)
+			return err;
+		cal_y1 = (((cal1 & 0xc) >> 2) << 8) | cal0;
+		break;
+	}
+	default:
+		return -ENODEV;
+	}
+
+	err = dev->tf->read(dev->dev, addr_x0, sizeof(cal_x0), (u8 *)&cal_x0);
+	if (err < 0)
+		return err;
+	cal_x0 = le16_to_cpu(cal_x0);
+
+	err = dev->tf->read(dev->dev, addr_x1, sizeof(cal_x1), (u8 *)&cal_x1);
+	if (err < 0)
+		return err;
+	cal_x1 = le16_to_cpu(cal_x1);
+
+	slope = &sensor->slope;
+	b_gen = &sensor->b_gen;
+
+	*slope = ((cal_y1 - cal_y0) * 8000) / (cal_x1 - cal_x0);
+	*b_gen = (((s32)cal_x1 * cal_y0 - (s32)cal_x0 * cal_y1) * 1000) /
+		 (cal_x1 - cal_x0);
+	*b_gen *= 8;
+
+	return 0;
+}
+
+static int hts221_read_raw(struct iio_dev *iio_dev,
+			   struct iio_chan_spec const *ch,
+			   int *val, int *val2, long mask)
+{
+	struct hts221_dev *dev = iio_priv(iio_dev);
+	int ret;
+
+	ret = iio_device_claim_direct_mode(iio_dev);
+	if (ret)
+		return ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		u8 data[HTS221_DATA_SIZE];
+
+		ret = hts221_dev_power_on(dev);
+		if (ret < 0)
+			goto out;
+
+		msleep(50);
+
+		ret = dev->tf->read(dev->dev, ch->address, sizeof(data), data);
+		if (ret < 0)
+			goto out;
+
+		ret = hts221_dev_power_off(dev);
+		if (ret < 0)
+			goto out;
+
+		*val = (s16)get_unaligned_le16(data);
+		ret = IIO_VAL_INT;
+
+		break;
+	}
+	case IIO_CHAN_INFO_SCALE: {
+		s64 tmp;
+		s32 rem, div, data;
+
+		switch (ch->type) {
+		case IIO_HUMIDITYRELATIVE:
+			data = dev->sensors[HTS221_SENSOR_H].slope;
+			div = (1 << 4) * 1000;
+			break;
+		case IIO_TEMP:
+			data = dev->sensors[HTS221_SENSOR_T].slope;
+			div = (1 << 6) * 1000;
+			break;
+		default:
+			goto out;
+		}
+
+		tmp = div_s64(data * 1000000000LL, div);
+		tmp = div_s64_rem(tmp, 1000000000LL, &rem);
+
+		*val = tmp;
+		*val2 = rem;
+		ret = IIO_VAL_INT_PLUS_NANO;
+		break;
+	}
+	case IIO_CHAN_INFO_OFFSET: {
+		s64 tmp;
+		s32 rem, div, data;
+
+		switch (ch->type) {
+		case IIO_HUMIDITYRELATIVE:
+			data = dev->sensors[HTS221_SENSOR_H].b_gen;
+			div = dev->sensors[HTS221_SENSOR_H].slope;
+			break;
+		case IIO_TEMP:
+			data = dev->sensors[HTS221_SENSOR_T].b_gen;
+			div = dev->sensors[HTS221_SENSOR_T].slope;
+			break;
+		default:
+			goto out;
+		}
+
+		tmp = div_s64(data * 1000000000LL, div);
+		tmp = div_s64_rem(tmp, 1000000000LL, &rem);
+
+		*val = tmp;
+		*val2 = abs(rem);
+		ret = IIO_VAL_INT_PLUS_NANO;
+		break;
+	}
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = dev->odr;
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO: {
+		u8 idx;
+		const struct hts221_avg *avg;
+
+		switch (ch->type) {
+		case IIO_HUMIDITYRELATIVE:
+			avg = &hts221_avg_list[HTS221_SENSOR_H];
+			idx = dev->sensors[HTS221_SENSOR_H].cur_avg_idx;
+			break;
+		case IIO_TEMP:
+			avg = &hts221_avg_list[HTS221_SENSOR_T];
+			idx = dev->sensors[HTS221_SENSOR_T].cur_avg_idx;
+			break;
+		default:
+			goto out;
+		}
+
+		*val = avg->avg_avl[idx].avg;
+		ret = IIO_VAL_INT;
+		break;
+	}
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+out:
+	iio_device_release_direct_mode(iio_dev);
+
+	return ret;
+}
+
+static int hts221_write_raw(struct iio_dev *iio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long mask)
+{
+	struct hts221_dev *dev = iio_priv(iio_dev);
+	int ret;
+
+	ret = iio_device_claim_direct_mode(iio_dev);
+	if (ret)
+		return ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = hts221_update_odr(dev, val);
+		break;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO: {
+		enum hts221_sensor_type type;
+
+		switch (chan->type) {
+		case IIO_HUMIDITYRELATIVE:
+			type = HTS221_SENSOR_H;
+			break;
+		case IIO_TEMP:
+			type = HTS221_SENSOR_T;
+			break;
+		default:
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = hts221_update_avg(&dev->sensors[type], val);
+		break;
+	}
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+out:
+	iio_device_release_direct_mode(iio_dev);
+
+	return ret;
+}
+
+static int hts221_validate_trigger(struct iio_dev *iio_dev,
+				   struct iio_trigger *trig)
+{
+	struct hts221_dev *dev = iio_priv(iio_dev);
+
+	return dev->trig == trig ? 0 : -EINVAL;
+}
+
+static IIO_DEVICE_ATTR(in_humidity_oversampling_ratio_available, S_IRUGO,
+		       hts221_sysfs_rh_oversampling_avail, NULL, 0);
+static IIO_DEVICE_ATTR(in_temp_oversampling_ratio_available, S_IRUGO,
+		       hts221_sysfs_temp_oversampling_avail, NULL, 0);
+static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(hts221_sysfs_sampling_freq);
+
+static struct attribute *hts221_attributes[] = {
+	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
+	&iio_dev_attr_in_humidity_oversampling_ratio_available.dev_attr.attr,
+	&iio_dev_attr_in_temp_oversampling_ratio_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group hts221_attribute_group = {
+	.attrs = hts221_attributes,
+};
+
+static const struct iio_info hts221_info = {
+	.driver_module = THIS_MODULE,
+	.attrs = &hts221_attribute_group,
+	.read_raw = hts221_read_raw,
+	.write_raw = hts221_write_raw,
+	.validate_trigger = hts221_validate_trigger,
+};
+
+static const unsigned long hts221_scan_masks[] = {0x3, 0x0};
+
+int hts221_probe(struct hts221_dev *dev)
+{
+	struct iio_dev *iio_dev = iio_priv_to_dev(dev);
+	int i, err;
+
+	mutex_init(&dev->lock);
+
+	err = hts221_check_whoami(dev);
+	if (err < 0)
+		return err;
+
+	err = hts221_update_odr(dev, 1);
+	if (err < 0)
+		return err;
+
+	dev->odr = hts221_odr_table[0].hz;
+
+	iio_dev->modes = INDIO_DIRECT_MODE;
+	iio_dev->dev.parent = dev->dev;
+	iio_dev->available_scan_masks = hts221_scan_masks;
+	iio_dev->channels = hts221_channels;
+	iio_dev->num_channels = ARRAY_SIZE(hts221_channels);
+	iio_dev->name = HTS221_DEV_NAME;
+	iio_dev->info = &hts221_info;
+
+	for (i = 0; i < HTS221_SENSOR_MAX; i++) {
+		dev->sensors[i].type = i;
+		dev->sensors[i].dev = dev;
+
+		err = hts221_update_avg(&dev->sensors[i],
+					hts221_avg_list[i].avg_avl[3].avg);
+		if (err < 0)
+			goto power_off;
+
+		err = hts221_parse_caldata(&dev->sensors[i]);
+		if (err < 0)
+			goto power_off;
+	}
+
+	err = hts221_dev_power_off(dev);
+	if (err < 0)
+		return err;
+
+	if (dev->irq > 0) {
+		err = hts221_allocate_buffers(dev);
+		if (err < 0)
+			return err;
+
+		err = hts221_allocate_triggers(dev);
+		if (err)
+			return err;
+	}
+
+	return devm_iio_device_register(dev->dev, iio_dev);
+
+power_off:
+	hts221_dev_power_off(dev);
+
+	return err;
+}
+EXPORT_SYMBOL(hts221_probe);
+
+MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>");
+MODULE_DESCRIPTION("STMicroelectronics hts221 sensor driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/humidity/hts221/hts221_i2c.c b/drivers/iio/humidity/hts221/hts221_i2c.c
new file mode 100644
index 0000000..fca9bad
--- /dev/null
+++ b/drivers/iio/humidity/hts221/hts221_i2c.c
@@ -0,0 +1,110 @@
+/*
+ * STMicroelectronics hts221 i2c driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include "hts221.h"
+
+#define I2C_AUTO_INCREMENT	0x80
+
+static int hts221_i2c_read(struct device *dev, u8 addr, int len, u8 *data)
+{
+	struct i2c_msg msg[2];
+	struct i2c_client *client = to_i2c_client(dev);
+
+	if (len > 1)
+		addr |= I2C_AUTO_INCREMENT;
+
+	msg[0].addr = client->addr;
+	msg[0].flags = client->flags;
+	msg[0].len = 1;
+	msg[0].buf = &addr;
+
+	msg[1].addr = client->addr;
+	msg[1].flags = client->flags | I2C_M_RD;
+	msg[1].len = len;
+	msg[1].buf = data;
+
+	return i2c_transfer(client->adapter, msg, 2);
+}
+
+static int hts221_i2c_write(struct device *dev, u8 addr, int len, u8 *data)
+{
+	u8 send[len + 1];
+	struct i2c_msg msg;
+	struct i2c_client *client = to_i2c_client(dev);
+
+	if (len > 1)
+		addr |= I2C_AUTO_INCREMENT;
+
+	send[0] = addr;
+	memcpy(&send[1], data, len * sizeof(u8));
+
+	msg.addr = client->addr;
+	msg.flags = client->flags;
+	msg.len = len + 1;
+	msg.buf = send;
+
+	return i2c_transfer(client->adapter, &msg, 1);
+}
+
+static const struct hts221_transfer_function hts221_transfer_fn = {
+	.read = hts221_i2c_read,
+	.write = hts221_i2c_write,
+};
+
+static int hts221_i2c_probe(struct i2c_client *client,
+			    const struct i2c_device_id *id)
+{
+	struct hts221_dev *dev;
+	struct iio_dev *iio_dev;
+
+	iio_dev = devm_iio_device_alloc(&client->dev, sizeof(*dev));
+	if (!iio_dev)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, iio_dev);
+
+	dev = iio_priv(iio_dev);
+	dev->name = client->name;
+	dev->dev = &client->dev;
+	dev->irq = client->irq;
+	dev->tf = &hts221_transfer_fn;
+
+	return hts221_probe(dev);
+}
+
+static const struct of_device_id hts221_i2c_of_match[] = {
+	{ .compatible = "st,hts221", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, hts221_i2c_of_match);
+
+static const struct i2c_device_id hts221_i2c_id_table[] = {
+	{ HTS221_DEV_NAME },
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, hts221_i2c_id_table);
+
+static struct i2c_driver hts221_driver = {
+	.driver = {
+		.name = "hts221_i2c",
+		.of_match_table = of_match_ptr(hts221_i2c_of_match),
+	},
+	.probe = hts221_i2c_probe,
+	.id_table = hts221_i2c_id_table,
+};
+module_i2c_driver(hts221_driver);
+
+MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>");
+MODULE_DESCRIPTION("STMicroelectronics hts221 i2c driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/humidity/hts221/hts221_spi.c b/drivers/iio/humidity/hts221/hts221_spi.c
new file mode 100644
index 0000000..f128165
--- /dev/null
+++ b/drivers/iio/humidity/hts221/hts221_spi.c
@@ -0,0 +1,125 @@
+/*
+ * STMicroelectronics hts221 spi driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
+ *
+ * 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 *device, u8 addr, int len, u8 *data)
+{
+	int err;
+	struct spi_device *spi = to_spi_device(device);
+	struct iio_dev *iio_dev = spi_get_drvdata(spi);
+	struct hts221_dev *dev = iio_priv(iio_dev);
+
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = dev->tb.tx_buf,
+			.bits_per_word = 8,
+			.len = 1,
+		},
+		{
+			.rx_buf = dev->tb.rx_buf,
+			.bits_per_word = 8,
+			.len = len,
+		}
+	};
+
+	if (len > 1)
+		addr |= SPI_AUTO_INCREMENT;
+	dev->tb.tx_buf[0] = addr | SENSORS_SPI_READ;
+
+	err = spi_sync_transfer(spi, xfers,  ARRAY_SIZE(xfers));
+	if (err < 0)
+		return err;
+
+	memcpy(data, dev->tb.rx_buf, len * sizeof(u8));
+
+	return len;
+}
+
+static int hts221_spi_write(struct device *device, u8 addr, int len, u8 *data)
+{
+	struct spi_device *spi = to_spi_device(device);
+	struct iio_dev *iio_dev = spi_get_drvdata(spi);
+	struct hts221_dev *dev = iio_priv(iio_dev);
+
+	struct spi_transfer xfers = {
+		.tx_buf = dev->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;
+	dev->tb.tx_buf[0] = addr;
+	memcpy(&dev->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_dev *dev;
+	struct iio_dev *iio_dev;
+
+	iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*dev));
+	if (!iio_dev)
+		return -ENOMEM;
+
+	spi_set_drvdata(spi, iio_dev);
+
+	dev = iio_priv(iio_dev);
+	dev->name = spi->modalias;
+	dev->dev = &spi->dev;
+	dev->irq = spi->irq;
+	dev->tf = &hts221_transfer_fn;
+
+	return hts221_probe(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-qxv4g6HH51o@public.gmane.org>");
+MODULE_DESCRIPTION("STMicroelectronics hts221 spi driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4

Re: [PATCH v3 1/2] iio: humidity: add support to hts221 rh/temp combo device

[Jonathan Cameron]

On 08/10/16 08:45, Lorenzo Bianconi wrote:
> 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-qxv4g6HH51o@public.gmane.org>
Hi Lorenzo,

This is coming together nicely.  Various minor bits inline.

The combined buffering you now have has a few issues to do
with the fact that we need to push whole 'scans' i.e. all enabled
channels to the buffer every time we trigger.

Firstly I'd drop the trigger entirely (or you could make it happen only
after the second channel arrives) and instead push directly to the buffer
from the main interrupt handler.  This is perfectly valid in IIO and lots
of devices do it (when their data stream doesn't align well with the trigger
concept - fifos being the classic case).

Secondly you need to make sure you have a whole scan every time.  So if
both channels are enabled, then both must be present. Here they are
both always enabled so you need to push them both.

Pitty you can't make it just interrupt on one of the channels as that would
make life much easier if it was always the second one.

Could be cynical and only do anything with the interrupt clearing once both
bits are set, but that will cause grief with the IRQ_RISING case.
I'm guessing this is really only a level interrupt but we can get away with
the rising case as it is slow.
Otherwise you can read the status, be told that channel isn't ready yet
so don't read it (but read the other that is afterwards) and have the
first channel set in the meantime.  No interrupt then occurs.

Might be safer to only allow the level interrupt (we went through this
with the mega st sensors driver as both Linus Waleij and I had those
wired up to edge triggered only interrupt chips and needed to bodge our way
around that). Have a look at how hideous that became  if you want to
groan - and that was the best we could do.

If you do only allow the level case it's not a great help as you'll either
spin in and out of the interrupt handler whilst waiting for the second
channel or still have to cache the first value then wait for the second
to trigger the interrupt again.

What fun.

Thanks,

Jonathan
> ---
>  drivers/iio/humidity/Kconfig                |   2 +
>  drivers/iio/humidity/Makefile               |   1 +
>  drivers/iio/humidity/hts221/Kconfig         |  23 +
>  drivers/iio/humidity/hts221/Makefile        |   6 +
>  drivers/iio/humidity/hts221/hts221.h        |  78 ++++
>  drivers/iio/humidity/hts221/hts221_buffer.c | 168 +++++++
>  drivers/iio/humidity/hts221/hts221_core.c   | 684 ++++++++++++++++++++++++++++
>  drivers/iio/humidity/hts221/hts221_i2c.c    | 110 +++++
>  drivers/iio/humidity/hts221/hts221_spi.c    | 125 +++++
>  9 files changed, 1197 insertions(+)
>  create mode 100644 drivers/iio/humidity/hts221/Kconfig
>  create mode 100644 drivers/iio/humidity/hts221/Makefile
>  create mode 100644 drivers/iio/humidity/hts221/hts221.h
>  create mode 100644 drivers/iio/humidity/hts221/hts221_buffer.c
>  create mode 100644 drivers/iio/humidity/hts221/hts221_core.c
>  create mode 100644 drivers/iio/humidity/hts221/hts221_i2c.c
>  create mode 100644 drivers/iio/humidity/hts221/hts221_spi.c
> 
> diff --git a/drivers/iio/humidity/Kconfig b/drivers/iio/humidity/Kconfig
> index b17e2e2..4ce75da 100644
> --- a/drivers/iio/humidity/Kconfig
> +++ b/drivers/iio/humidity/Kconfig
> @@ -69,4 +69,6 @@ config SI7020
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called si7020.
>  
> +source "drivers/iio/humidity/hts221/Kconfig"
> +
Not to my mind worthy of it's own directory.  Just pull it in directly under
the humidity dir.  It's a compact and well organised driver unlike
the beasts we tend to shove off into their own directory.

>  endmenu
> diff --git a/drivers/iio/humidity/Makefile b/drivers/iio/humidity/Makefile
> index 4a73442..25e11f3 100644
> --- a/drivers/iio/humidity/Makefile
> +++ b/drivers/iio/humidity/Makefile
> @@ -5,6 +5,7 @@
>  obj-$(CONFIG_AM2315) += am2315.o
>  obj-$(CONFIG_DHT11) += dht11.o
>  obj-$(CONFIG_HDC100X) += hdc100x.o
> +obj-$(CONFIG_HTS221) += hts221/
>  obj-$(CONFIG_HTU21) += htu21.o
>  obj-$(CONFIG_SI7005) += si7005.o
>  obj-$(CONFIG_SI7020) += si7020.o
> diff --git a/drivers/iio/humidity/hts221/Kconfig b/drivers/iio/humidity/hts221/Kconfig
> new file mode 100644
> index 0000000..c10013d
> --- /dev/null
> +++ b/drivers/iio/humidity/hts221/Kconfig
> @@ -0,0 +1,23 @@
> +
> +config HTS221
> +	tristate "STMicroelectronics HTS221 sensor Driver"
> +	depends on (I2C || SPI)
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	select HTS221_I2C if (I2C)
> +	select HTS221_SPI if (SPI_MASTER)
> +	help
> +	  Say yes here to build support for STMicroelectronics HTS221
> +	  temperature-humidity sensor
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called hts221.
> +
> +config HTS221_I2C
> +	tristate
> +	depends on HTS221
> +
> +config HTS221_SPI
> +	tristate
> +	depends on HTS221
> +
> diff --git a/drivers/iio/humidity/hts221/Makefile b/drivers/iio/humidity/hts221/Makefile
> new file mode 100644
> index 0000000..e1f5464
> --- /dev/null
> +++ b/drivers/iio/humidity/hts221/Makefile
> @@ -0,0 +1,6 @@
> +hts221-y := hts221_core.o \
> +	    hts221_buffer.o
> +
> +obj-$(CONFIG_HTS221) += hts221.o
> +obj-$(CONFIG_HTS221_I2C) += hts221_i2c.o
> +obj-$(CONFIG_HTS221_SPI) += hts221_spi.o
> diff --git a/drivers/iio/humidity/hts221/hts221.h b/drivers/iio/humidity/hts221/hts221.h
> new file mode 100644
> index 0000000..6e06e6a
> --- /dev/null
> +++ b/drivers/iio/humidity/hts221/hts221.h
> @@ -0,0 +1,78 @@
> +/*
> + * STMicroelectronics hts221 sensor driver
> + *
> + * Copyright 2016 STMicroelectronics Inc.
> + *
> + * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
> + *
> + * 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 {
> +	struct hts221_dev *dev;
> +
> +	enum hts221_sensor_type type;
> +	u8 cur_avg_idx;
> +	int slope, b_gen;
> +};
> +
> +struct hts221_dev {
> +	const char *name;
> +	struct device *dev;
> +
> +	struct mutex lock;
> +
> +	u8 buffer[ALIGN(2 * HTS221_DATA_SIZE, sizeof(s64)) + sizeof(s64)];
> +	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_dev *dev, bool enable);
> +int hts221_probe(struct hts221_dev *dev);
> +int hts221_dev_power_on(struct hts221_dev *dev);
> +int hts221_dev_power_off(struct hts221_dev *dev);
> +int hts221_allocate_buffers(struct hts221_dev *dev);
> +int hts221_allocate_triggers(struct hts221_dev *dev);
> +
> +#endif /* HTS221_H */
> diff --git a/drivers/iio/humidity/hts221/hts221_buffer.c b/drivers/iio/humidity/hts221/hts221_buffer.c
> new file mode 100644
> index 0000000..69330b7
> --- /dev/null
> +++ b/drivers/iio/humidity/hts221/hts221_buffer.c
> @@ -0,0 +1,168 @@
> +/*
> + * STMicroelectronics hts221 sensor driver
> + *
> + * Copyright 2016 STMicroelectronics Inc.
> + *
> + * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
> + *
> + * 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_dev *dev = iio_priv(iio_dev);
> +
> +	return hts221_config_drdy(dev, 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_dev *dev = (struct hts221_dev *)private;
> +	struct iio_dev *iio_dev = iio_priv_to_dev(dev);
> +	struct iio_chan_spec const *ch;
> +	int err, count = 0;
> +	u8 status;
> +
> +	err = dev->tf->read(dev->dev, HTS221_REG_STATUS_ADDR, sizeof(status),
> +			    &status);
> +	if (err < 0)
> +		return IRQ_HANDLED;
> +
> +	/* humidity data */
> +	if (status & HTS221_RH_DRDY_MASK) {
> +		ch = &iio_dev->channels[HTS221_SENSOR_H];
> +		err = dev->tf->read(dev->dev, ch->address, HTS221_DATA_SIZE,
> +				    dev->buffer);
> +		if (err < 0)
> +			return IRQ_HANDLED;
> +
> +		count++;
> +	}
> +
> +	/* temperature data */
> +	if (status & HTS221_TEMP_DRDY_MASK) {
> +		ch = &iio_dev->channels[HTS221_SENSOR_T];
> +		err = dev->tf->read(dev->dev, ch->address, HTS221_DATA_SIZE,
> +				    dev->buffer + 2 * count);
> +		if (err < 0)
> +			return IRQ_HANDLED;
> +
> +		count++;
> +	}
> +
> +	if (count > 0) {
> +		iio_trigger_poll_chained(dev->trig);
> +		return IRQ_HANDLED;
This is odd enough I'd kill off the trigger and have it run as
a direct buffer device.  There is no 'necessity' to have a trigger. It
just allows us to hang multiple devices together when sampling.

As it runs here (I think) we will end up sometimes pushing one sample and
sometimes 2 depending on how quickly we get here after the interrupt.

That makes for some nasty semantics for this trigger.

Hence drop the trigger at which point it becomes unsual handling inside
the driver which is fine ;)

You should cache values until you have a pair however otherwise any
client drivers will get their data turning up in partial scans which would
be a mess.  So only push to buffers complete 'scans' which will be both
channels if they are both enabled.

> +	} else {
> +		return IRQ_NONE;
> +	}
> +}
> +
> +int hts221_allocate_triggers(struct hts221_dev *dev)
> +{
> +	struct iio_dev *iio_dev = iio_priv_to_dev(dev);
> +	unsigned long irq_type;
> +	int err;
> +
> +	irq_type = irqd_get_trigger_type(irq_get_irq_data(dev->irq));
> +
> +	switch (irq_type) {
> +	case IRQF_TRIGGER_HIGH:
> +	case IRQF_TRIGGER_RISING:
> +		break;
> +	default:
> +		dev_info(dev->dev,
> +			 "mode %lx unsupported, using IRQF_TRIGGER_RISING\n",
> +			 irq_type);
> +		irq_type = IRQF_TRIGGER_RISING;
> +		break;
> +	}
> +
> +	err = devm_request_threaded_irq(dev->dev, dev->irq, NULL,
> +					hts221_trigger_handler_thread,
> +					irq_type | IRQF_ONESHOT,
> +					dev->name, dev);
> +	if (err) {
> +		dev_err(dev->dev, "failed to request trigger irq %d\n",
> +			dev->irq);
> +		return err;
> +	}
> +
> +	dev->trig = devm_iio_trigger_alloc(dev->dev, "%s-trigger",
> +					   iio_dev->name);
> +	if (!dev->trig)
> +		return -ENOMEM;
> +
> +	iio_trigger_set_drvdata(dev->trig, iio_dev);
> +	dev->trig->ops = &hts221_trigger_ops;
> +	dev->trig->dev.parent = dev->dev;
> +	iio_dev->trig = iio_trigger_get(dev->trig);
> +
> +	return devm_iio_trigger_register(dev->dev, dev->trig);
> +}
> +
> +static int hts221_buffer_preenable(struct iio_dev *iio_dev)
> +{
> +	return hts221_dev_power_on(iio_priv(iio_dev));
> +}
> +
> +static int hts221_buffer_postdisable(struct iio_dev *iio_dev)
> +{
> +	return hts221_dev_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)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *iio_dev = pf->indio_dev;
> +	struct hts221_dev *dev = iio_priv(iio_dev);
> +
Suprised me that the read wasn't in here...
> +	iio_push_to_buffers_with_timestamp(iio_dev, dev->buffer,
> +					   iio_get_time_ns(iio_dev));
> +	iio_trigger_notify_done(dev->trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +int hts221_allocate_buffers(struct hts221_dev *dev)
> +{
> +	return devm_iio_triggered_buffer_setup(dev->dev, iio_priv_to_dev(dev),
> +					NULL, hts221_buffer_handler_thread,
> +					&hts221_buffer_ops);
> +}
> +
> +MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>");
> +MODULE_DESCRIPTION("STMicroelectronics hts221 buffer driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/humidity/hts221/hts221_core.c b/drivers/iio/humidity/hts221/hts221_core.c
> new file mode 100644
> index 0000000..a537798
> --- /dev/null
> +++ b/drivers/iio/humidity/hts221/hts221_core.c
> @@ -0,0 +1,684 @@
> +/*
> + * STMicroelectronics hts221 sensor driver
> + *
> + * Copyright 2016 STMicroelectronics Inc.
> + *
> + * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/delay.h>
> +#include <asm/unaligned.h>
> +
> +#include "hts221.h"
> +
> +#define HTS221_REG_WHOAMI_ADDR		0x0f
> +#define HTS221_REG_WHOAMI_VAL		0xbc
> +
> +#define HTS221_REG_CNTRL1_ADDR		0x20
> +#define HTS221_REG_CNTRL2_ADDR		0x21
> +#define HTS221_REG_CNTRL3_ADDR		0x22
> +
> +#define HTS221_REG_AVG_ADDR		0x10
> +#define HTS221_REG_H_OUT_L		0x28
> +#define HTS221_REG_T_OUT_L		0x2a
> +
> +#define HTS221_HUMIDITY_AVG_MASK	0x07
> +#define HTS221_TEMP_AVG_MASK		0x38
> +
> +#define HTS221_ODR_MASK			0x87
> +#define HTS221_BDU_MASK			BIT(2)
> +
> +#define HTS221_DRDY_MASK		BIT(2)
> +
> +#define HTS221_ENABLE_SENSOR		BIT(7)
> +
> +#define HTS221_HUMIDITY_AVG_4		0x00 /* 0.4 %RH */
> +#define HTS221_HUMIDITY_AVG_8		0x01 /* 0.3 %RH */
> +#define HTS221_HUMIDITY_AVG_16		0x02 /* 0.2 %RH */
> +#define HTS221_HUMIDITY_AVG_32		0x03 /* 0.15 %RH */
> +#define HTS221_HUMIDITY_AVG_64		0x04 /* 0.1 %RH */
> +#define HTS221_HUMIDITY_AVG_128		0x05 /* 0.07 %RH */
> +#define HTS221_HUMIDITY_AVG_256		0x06 /* 0.05 %RH */
> +#define HTS221_HUMIDITY_AVG_512		0x07 /* 0.03 %RH */
> +
> +#define HTS221_TEMP_AVG_2		0x00 /* 0.08 degC */
> +#define HTS221_TEMP_AVG_4		0x08 /* 0.05 degC */
> +#define HTS221_TEMP_AVG_8		0x10 /* 0.04 degC */
> +#define HTS221_TEMP_AVG_16		0x18 /* 0.03 degC */
> +#define HTS221_TEMP_AVG_32		0x20 /* 0.02 degC */
> +#define HTS221_TEMP_AVG_64		0x28 /* 0.015 degC */
> +#define HTS221_TEMP_AVG_128		0x30 /* 0.01 degC */
> +#define HTS221_TEMP_AVG_256		0x38 /* 0.007 degC */
> +
> +/* calibration registers */
> +#define HTS221_REG_0RH_CAL_X_H		0x36
> +#define HTS221_REG_1RH_CAL_X_H		0x3a
> +#define HTS221_REG_0RH_CAL_Y_H		0x30
> +#define HTS221_REG_1RH_CAL_Y_H		0x31
> +#define HTS221_REG_0T_CAL_X_L		0x3c
> +#define HTS221_REG_1T_CAL_X_L		0x3e
> +#define HTS221_REG_0T_CAL_Y_H		0x32
> +#define HTS221_REG_1T_CAL_Y_H		0x33
> +#define HTS221_REG_T1_T0_CAL_Y_H	0x35
> +
> +struct hts221_odr {
> +	u8 hz;
> +	u8 val;
> +};
> +
> +struct hts221_avg {
> +	u8 addr;
> +	u8 mask;
> +	struct hts221_avg_avl avg_avl[HTS221_AVG_DEPTH];
> +};
> +
> +static const struct hts221_odr hts221_odr_table[] = {
> +	{ 1, 0x01 },	/* 1Hz */
> +	{ 7, 0x02 },	/* 7Hz */
> +	{ 13, 0x03 },	/* 12.5Hz */
> +};
> +
> +static const struct hts221_avg hts221_avg_list[] = {
> +	{
> +		.addr = HTS221_REG_AVG_ADDR,
> +		.mask = HTS221_HUMIDITY_AVG_MASK,
> +		.avg_avl = {
> +			{ 4, HTS221_HUMIDITY_AVG_4 },
> +			{ 8, HTS221_HUMIDITY_AVG_8 },
> +			{ 16, HTS221_HUMIDITY_AVG_16 },
> +			{ 32, HTS221_HUMIDITY_AVG_32 },
> +			{ 64, HTS221_HUMIDITY_AVG_64 },
> +			{ 128, HTS221_HUMIDITY_AVG_128 },
> +			{ 256, HTS221_HUMIDITY_AVG_256 },
> +			{ 512, HTS221_HUMIDITY_AVG_512 },
> +		},
> +	},
> +	{
> +		.addr = HTS221_REG_AVG_ADDR,
> +		.mask = HTS221_TEMP_AVG_MASK,
> +		.avg_avl = {
> +			{ 2, HTS221_TEMP_AVG_2 },
> +			{ 4, HTS221_TEMP_AVG_4 },
> +			{ 8, HTS221_TEMP_AVG_8 },
> +			{ 16, HTS221_TEMP_AVG_16 },
> +			{ 32, HTS221_TEMP_AVG_32 },
> +			{ 64, HTS221_TEMP_AVG_64 },
> +			{ 128, HTS221_TEMP_AVG_128 },
> +			{ 256, HTS221_TEMP_AVG_256 },
> +		},
> +	},
> +};
> +
> +static const struct iio_chan_spec hts221_channels[] = {
> +	{
> +		.type = IIO_HUMIDITYRELATIVE,
> +		.address = HTS221_REG_H_OUT_L,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_OFFSET) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
> +				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
> +		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.scan_index = 0,
> +		.scan_type = {
> +			.sign = 's',
> +			.realbits = 16,
> +			.storagebits = 16,
> +			.endianness = IIO_LE,
> +		},
> +	},
> +	{
> +		.type = IIO_TEMP,
> +		.address = HTS221_REG_T_OUT_L,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_OFFSET) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
> +				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
> +		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.scan_index = 1,
> +		.scan_type = {
> +			.sign = 's',
> +			.realbits = 16,
> +			.storagebits = 16,
> +			.endianness = IIO_LE,
> +		},
> +	},
> +	IIO_CHAN_SOFT_TIMESTAMP(2),
> +};
> +
> +static int hts221_write_with_mask(struct hts221_dev *dev, u8 addr, u8 mask,
> +				  u8 val)
> +{
> +	u8 data;
> +	int err;
> +
> +	mutex_lock(&dev->lock);
> +
> +	err = dev->tf->read(dev->dev, addr, sizeof(data), &data);
> +	if (err < 0) {
> +		dev_err(dev->dev, "failed to read %02x register\n", addr);
Looks like a good spot for a goto error_unlock then return err at
the end of this function.

Makes it slightly less likely someone will mess up the locking in the future.
> +		mutex_unlock(&dev->lock);
> +
> +		return err;
> +	}
> +
> +	data = (data & ~mask) | (val & mask);
> +
> +	err = dev->tf->write(dev->dev, addr, sizeof(data), &data);
> +	if (err < 0) {
> +		dev_err(dev->dev, "failed to write %02x register\n", addr);
> +		mutex_unlock(&dev->lock);
> +
> +		return err;
> +	}
> +
> +	mutex_unlock(&dev->lock);
> +
> +	return 0;
> +}
> +
> +static int hts221_check_whoami(struct hts221_dev *dev)
> +{
> +	u8 data;
> +	int err;
> +
> +	err = dev->tf->read(dev->dev, HTS221_REG_WHOAMI_ADDR, sizeof(data),
> +			    &data);
> +	if (err < 0) {
> +		dev_err(dev->dev, "failed to read whoami register\n");
> +		return err;
> +	}
> +
> +	if (data != HTS221_REG_WHOAMI_VAL) {
> +		dev_err(dev->dev, "wrong whoami {%02x vs %02x}\n",
> +			data, HTS221_REG_WHOAMI_VAL);
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +int hts221_config_drdy(struct hts221_dev *dev, bool enable)
> +{
> +	u8 val = enable ? BIT(2) : 0;
BIT(2)? As opposed to HTS221_DRDY_MASK
> +
> +	return hts221_write_with_mask(dev, HTS221_REG_CNTRL3_ADDR,
> +				      HTS221_DRDY_MASK, val);
> +}
> +
> +static int hts221_update_odr(struct hts221_dev *dev, u8 odr)
> +{
> +	int i, err;
> +	u8 val;
> +
> +	for (i = 0; i < ARRAY_SIZE(hts221_odr_table); i++)
> +		if (hts221_odr_table[i].hz == odr)
> +			break;
> +
> +	if (i == ARRAY_SIZE(hts221_odr_table))
> +		return -EINVAL;
> +
> +	val = HTS221_ENABLE_SENSOR | HTS221_BDU_MASK | hts221_odr_table[i].val;
> +	err = hts221_write_with_mask(dev, HTS221_REG_CNTRL1_ADDR,
> +				     HTS221_ODR_MASK, val);
> +	if (err < 0)
> +		return err;
> +
> +	dev->odr = odr;
> +
> +	return 0;
> +}
> +
> +static int hts221_update_avg(struct hts221_sensor *sensor, u16 val)
> +{
> +	int i, err;
> +	const struct hts221_avg *avg = &hts221_avg_list[sensor->type];
> +
> +	for (i = 0; i < HTS221_AVG_DEPTH; i++)
> +		if (avg->avg_avl[i].avg == val)
> +			break;
> +
> +	if (i == HTS221_AVG_DEPTH)
> +		return -EINVAL;
> +
> +	err = hts221_write_with_mask(sensor->dev, avg->addr, avg->mask,
> +				     avg->avg_avl[i].val);
> +	if (err < 0)
> +		return err;
> +
> +	sensor->cur_avg_idx = i;
> +
> +	return 0;
> +}
> +
> +static ssize_t hts221_sysfs_sampling_freq(struct device *dev,
> +					  struct device_attribute *attr,
> +					  char *buf)
> +{
> +	int i;
> +	ssize_t len = 0;
> +
> +	for (i = 0; i < ARRAY_SIZE(hts221_odr_table); i++)
> +		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
> +				 hts221_odr_table[i].hz);
> +	buf[len - 1] = '\n';
> +
> +	return len;
> +}
> +
> +static ssize_t
> +hts221_sysfs_rh_oversampling_avail(struct device *dev,
> +				   struct device_attribute *attr,
> +				   char *buf)
> +{
> +	const struct hts221_avg *avg = &hts221_avg_list[HTS221_SENSOR_H];
> +	ssize_t len = 0;
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(avg->avg_avl); i++)
> +		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
> +				 avg->avg_avl[i].avg);
> +	buf[len - 1] = '\n';
> +
> +	return len;
> +}
> +
> +static ssize_t
> +hts221_sysfs_temp_oversampling_avail(struct device *dev,
> +				     struct device_attribute *attr,
> +				     char *buf)
> +{
> +	const struct hts221_avg *avg = &hts221_avg_list[HTS221_SENSOR_T];
> +	ssize_t len = 0;
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(avg->avg_avl); i++)
> +		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
> +				 avg->avg_avl[i].avg);
> +	buf[len - 1] = '\n';
> +
> +	return len;
> +}
> +
> +int hts221_dev_power_on(struct hts221_dev *dev)
> +{
> +	struct hts221_sensor *sensor;
> +	int i, err, val;
> +
> +	for (i = 0; i < HTS221_SENSOR_MAX; i++) {
> +		sensor = &dev->sensors[i];
> +		val = hts221_avg_list[i].avg_avl[sensor->cur_avg_idx].avg;
> +
> +		err = hts221_update_avg(sensor, val);
> +		if (err < 0)
> +			return err;
> +	}
> +
> +	err = hts221_update_odr(dev, dev->odr);
> +	if (err < 0)
> +		return err;
> +
> +	return 0;
> +}
> +
> +int hts221_dev_power_off(struct hts221_dev *dev)
> +{
> +	u8 data[] = {0x00, 0x00};
> +
> +	return dev->tf->write(dev->dev, HTS221_REG_CNTRL1_ADDR, sizeof(data),
> +			      data);
> +}
> +
Ouch to the next function.  That's irritatingly random difference between
the two calibrations. I'd almost be tempted to separate them entirely
and just have two functions.  The shared code isn't huge and the 16 vs 8 bit
cal values left me wondering what was going on in here for a few moments.

What do you think?
> +static int hts221_parse_caldata(struct hts221_sensor *sensor)
> +{
> +	int err, *slope, *b_gen;
> +	u8 addr_x0, addr_x1;
> +	s16 cal_x0, cal_x1, cal_y0, cal_y1;
> +	struct hts221_dev *dev = sensor->dev;
> +
> +	switch (sensor->type) {
> +	case HTS221_SENSOR_H: {
> +		u8 data;
> +
> +		addr_x0 = HTS221_REG_0RH_CAL_X_H;
> +		addr_x1 = HTS221_REG_1RH_CAL_X_H;
> +		cal_y1 = 0;
> +		cal_y0 = 0;
> +
> +		err = dev->tf->read(dev->dev, HTS221_REG_0RH_CAL_Y_H,
> +				    sizeof(data), &data);
> +		if (err < 0)
> +			return err;
> +		cal_y0 = data;
> +
> +		err = dev->tf->read(dev->dev, HTS221_REG_1RH_CAL_Y_H,
> +				    sizeof(data), &data);
> +		if (err < 0)
> +			return err;
> +		cal_y1 = data;
> +
> +		break;
> +	}
> +	case HTS221_SENSOR_T: {
> +		u8 cal0, cal1;
> +
> +		addr_x0 = HTS221_REG_0T_CAL_X_L;
> +		addr_x1 = HTS221_REG_1T_CAL_X_L;
> +
> +		err = dev->tf->read(dev->dev, HTS221_REG_0T_CAL_Y_H,
> +				    sizeof(cal0), &cal0);
> +		if (err < 0)
> +			return err;
> +
> +		err = dev->tf->read(dev->dev, HTS221_REG_T1_T0_CAL_Y_H,
> +				    sizeof(cal1), &cal1);
> +		if (err < 0)
> +			return err;
> +		cal_y0 = (le16_to_cpu(cal1 & 0x3) << 8) | cal0;
> +
> +		err = dev->tf->read(dev->dev, HTS221_REG_1T_CAL_Y_H,
> +				    sizeof(cal0), &cal0);
> +		if (err < 0)
> +			return err;
> +
> +		err = dev->tf->read(dev->dev, HTS221_REG_T1_T0_CAL_Y_H,
> +				    sizeof(cal1), &cal1);
> +		if (err < 0)
> +			return err;
> +		cal_y1 = (((cal1 & 0xc) >> 2) << 8) | cal0;
> +		break;
> +	}
> +	default:
> +		return -ENODEV;
> +	}
> +
> +	err = dev->tf->read(dev->dev, addr_x0, sizeof(cal_x0), (u8 *)&cal_x0);
> +	if (err < 0)
> +		return err;
> +	cal_x0 = le16_to_cpu(cal_x0);
> +
> +	err = dev->tf->read(dev->dev, addr_x1, sizeof(cal_x1), (u8 *)&cal_x1);
> +	if (err < 0)
> +		return err;
> +	cal_x1 = le16_to_cpu(cal_x1);
> +
> +	slope = &sensor->slope;
> +	b_gen = &sensor->b_gen;
> +
> +	*slope = ((cal_y1 - cal_y0) * 8000) / (cal_x1 - cal_x0);
> +	*b_gen = (((s32)cal_x1 * cal_y0 - (s32)cal_x0 * cal_y1) * 1000) /
> +		 (cal_x1 - cal_x0);
> +	*b_gen *= 8;
> +
> +	return 0;
> +}
> +
> +static int hts221_read_raw(struct iio_dev *iio_dev,
> +			   struct iio_chan_spec const *ch,
> +			   int *val, int *val2, long mask)
> +{
> +	struct hts221_dev *dev = iio_priv(iio_dev);
> +	int ret;
> +
> +	ret = iio_device_claim_direct_mode(iio_dev);
> +	if (ret)
> +		return ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW: {
> +		u8 data[HTS221_DATA_SIZE];
> +
> +		ret = hts221_dev_power_on(dev);
> +		if (ret < 0)
> +			goto out;
> +
> +		msleep(50);
> +
> +		ret = dev->tf->read(dev->dev, ch->address, sizeof(data), data);
> +		if (ret < 0)
> +			goto out;
> +
> +		ret = hts221_dev_power_off(dev);
> +		if (ret < 0)
> +			goto out;
> +
> +		*val = (s16)get_unaligned_le16(data);
> +		ret = IIO_VAL_INT;
> +
> +		break;
> +	}
> +	case IIO_CHAN_INFO_SCALE: {
> +		s64 tmp;
> +		s32 rem, div, data;
> +
> +		switch (ch->type) {
> +		case IIO_HUMIDITYRELATIVE:
> +			data = dev->sensors[HTS221_SENSOR_H].slope;
> +			div = (1 << 4) * 1000;
> +			break;
> +		case IIO_TEMP:
> +			data = dev->sensors[HTS221_SENSOR_T].slope;
> +			div = (1 << 6) * 1000;
> +			break;
> +		default:
> +			goto out;
> +		}
> +
> +		tmp = div_s64(data * 1000000000LL, div);
> +		tmp = div_s64_rem(tmp, 1000000000LL, &rem);
> +
> +		*val = tmp;
> +		*val2 = rem;
> +		ret = IIO_VAL_INT_PLUS_NANO;
> +		break;
> +	}
> +	case IIO_CHAN_INFO_OFFSET: {
> +		s64 tmp;
> +		s32 rem, div, data;
> +
> +		switch (ch->type) {
> +		case IIO_HUMIDITYRELATIVE:
> +			data = dev->sensors[HTS221_SENSOR_H].b_gen;
> +			div = dev->sensors[HTS221_SENSOR_H].slope;
> +			break;
> +		case IIO_TEMP:
> +			data = dev->sensors[HTS221_SENSOR_T].b_gen;
> +			div = dev->sensors[HTS221_SENSOR_T].slope;
> +			break;
> +		default:
Is ret set in this path?
Hmm. there is more here than below, so perhaps the slightly ugly goto out
is the best option.  I'd be tempted to factor out the IIO_CHAN_INFO_OFFSET
block into it's own function though as it's complicated enough to mean
that would make it slightly cleaner to read perhaps...

Probably worth doing for all the top level switch elements in here as
the whole function is a bit too bulky for my liking.

Side effect that we can get rid of all the goto out stuff ;)
> +			goto out;
> +		}
> +
> +		tmp = div_s64(data * 1000000000LL, div);
> +		tmp = div_s64_rem(tmp, 1000000000LL, &rem);
> +
> +		*val = tmp;
> +		*val2 = abs(rem);
Why abs? Remainder not guaranteed to be positive?
> +		ret = IIO_VAL_INT_PLUS_NANO;
> +		break;
> +	}
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*val = dev->odr;
> +		ret = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_OVERSAMPLING_RATIO: {
> +		u8 idx;
> +		const struct hts221_avg *avg;
> +
> +		switch (ch->type) {
> +		case IIO_HUMIDITYRELATIVE:
> +			avg = &hts221_avg_list[HTS221_SENSOR_H];
> +			idx = dev->sensors[HTS221_SENSOR_H].cur_avg_idx;
> +			break;
> +		case IIO_TEMP:
> +			avg = &hts221_avg_list[HTS221_SENSOR_T];
> +			idx = dev->sensors[HTS221_SENSOR_T].cur_avg_idx;
> +			break;
> +		default:
ret not set (I think) in this path. I'd set it explicitly here to
make it clear what is going on rather than doing an intiialize at the
beginning or anything horrible like that.
> +			goto out;
> +		}
> +
> +		*val = avg->avg_avl[idx].avg;
> +		ret = IIO_VAL_INT;
Similar comment to I made on the next function (I always review
backwards as drivers make more sense 'top down'.)
> +		break;
> +	}
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +out:
> +	iio_device_release_direct_mode(iio_dev);
> +
> +	return ret;
> +}
> +
> +static int hts221_write_raw(struct iio_dev *iio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val, int val2, long mask)
> +{
> +	struct hts221_dev *dev = iio_priv(iio_dev);
> +	int ret;
> +
> +	ret = iio_device_claim_direct_mode(iio_dev);
> +	if (ret)
> +		return ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret = hts221_update_odr(dev, val);
> +		break;
> +	case IIO_CHAN_INFO_OVERSAMPLING_RATIO: {
> +		enum hts221_sensor_type type;
> +
> +		switch (chan->type) {
> +		case IIO_HUMIDITYRELATIVE:
> +			type = HTS221_SENSOR_H;
> +			break;
> +		case IIO_TEMP:
> +			type = HTS221_SENSOR_T;
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			goto out;
Really minor personal taste bit coming up ;) Feel free to ignore this
one if you disagree!

Personally I'm never that keen on goto's out of switch statements. They
make for slightly confusing code to follow.  (not too bad here though!)

I'd be tempted to go with
		case IIO_HUMIDITYRELATIVE:
			ret = hts221_update_avg(&dev->sensors[HTS221_SENSOR_H],
						val);
			break;
		case IIO_TEMP:
			ret = hts221_update_avg(&dev->sensors[HTS221_SENSOR_T],
						val);
			break;
		}
		break;
		
> +		}
> +
> +		ret = hts221_update_avg(&dev->sensors[type], val);
> +		break;
> +	}
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +out:
> +	iio_device_release_direct_mode(iio_dev);
> +
> +	return ret;
> +}
> +
> +static int hts221_validate_trigger(struct iio_dev *iio_dev,
> +				   struct iio_trigger *trig)
> +{
> +	struct hts221_dev *dev = iio_priv(iio_dev);
> +
> +	return dev->trig == trig ? 0 : -EINVAL;
> +}
> +
> +static IIO_DEVICE_ATTR(in_humidity_oversampling_ratio_available, S_IRUGO,
> +		       hts221_sysfs_rh_oversampling_avail, NULL, 0);
> +static IIO_DEVICE_ATTR(in_temp_oversampling_ratio_available, S_IRUGO,
> +		       hts221_sysfs_temp_oversampling_avail, NULL, 0);
> +static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(hts221_sysfs_sampling_freq);
> +
> +static struct attribute *hts221_attributes[] = {
> +	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
> +	&iio_dev_attr_in_humidity_oversampling_ratio_available.dev_attr.attr,
> +	&iio_dev_attr_in_temp_oversampling_ratio_available.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group hts221_attribute_group = {
> +	.attrs = hts221_attributes,
> +};
> +
> +static const struct iio_info hts221_info = {
> +	.driver_module = THIS_MODULE,
> +	.attrs = &hts221_attribute_group,
> +	.read_raw = hts221_read_raw,
> +	.write_raw = hts221_write_raw,
> +	.validate_trigger = hts221_validate_trigger,
> +};
> +
> +static const unsigned long hts221_scan_masks[] = {0x3, 0x0};
> +
> +int hts221_probe(struct hts221_dev *dev)
> +{
> +	struct iio_dev *iio_dev = iio_priv_to_dev(dev);

I'd prefer you pass in the iio_dev pointer and go the other way.
Mostly because that's the way round that most drivers do it so it
is the 'obviously correct' option.

Took a lot of arguments to allow the iio_priv_to_dev function in
in the first place as it allows for this, but there are a few
tiny corners where it makes sense so we let it in.

> +	int i, err;
> +
> +	mutex_init(&dev->lock);
> +
> +	err = hts221_check_whoami(dev);
> +	if (err < 0)
> +		return err;
> +
> +	err = hts221_update_odr(dev, 1);
> +	if (err < 0)
> +		return err;
> +
> +	dev->odr = hts221_odr_table[0].hz;
> +
> +	iio_dev->modes = INDIO_DIRECT_MODE;
> +	iio_dev->dev.parent = dev->dev;
> +	iio_dev->available_scan_masks = hts221_scan_masks;
> +	iio_dev->channels = hts221_channels;
> +	iio_dev->num_channels = ARRAY_SIZE(hts221_channels);
> +	iio_dev->name = HTS221_DEV_NAME;
> +	iio_dev->info = &hts221_info;
> +
> +	for (i = 0; i < HTS221_SENSOR_MAX; i++) {
> +		dev->sensors[i].type = i;
> +		dev->sensors[i].dev = dev;
> +
> +		err = hts221_update_avg(&dev->sensors[i],
> +					hts221_avg_list[i].avg_avl[3].avg);
> +		if (err < 0)
> +			goto power_off;
> +
> +		err = hts221_parse_caldata(&dev->sensors[i]);
> +		if (err < 0)
> +			goto power_off;
> +	}
> +
> +	err = hts221_dev_power_off(dev);
> +	if (err < 0)
> +		return err;
> +
> +	if (dev->irq > 0) {
> +		err = hts221_allocate_buffers(dev);
> +		if (err < 0)
> +			return err;
> +
> +		err = hts221_allocate_triggers(dev);
> +		if (err)
> +			return err;
> +	}
> +
> +	return devm_iio_device_register(dev->dev, iio_dev);
> +
> +power_off:
> +	hts221_dev_power_off(dev);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL(hts221_probe);
> +
> +MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>");
> +MODULE_DESCRIPTION("STMicroelectronics hts221 sensor driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/humidity/hts221/hts221_i2c.c b/drivers/iio/humidity/hts221/hts221_i2c.c
> new file mode 100644
> index 0000000..fca9bad
> --- /dev/null
> +++ b/drivers/iio/humidity/hts221/hts221_i2c.c
> @@ -0,0 +1,110 @@
> +/*
> + * STMicroelectronics hts221 i2c driver
> + *
> + * Copyright 2016 STMicroelectronics Inc.
> + *
> + * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/slab.h>
> +#include "hts221.h"
> +
> +#define I2C_AUTO_INCREMENT	0x80
> +
> +static int hts221_i2c_read(struct device *dev, u8 addr, int len, u8 *data)
> +{
> +	struct i2c_msg msg[2];
> +	struct i2c_client *client = to_i2c_client(dev);
> +
> +	if (len > 1)
> +		addr |= I2C_AUTO_INCREMENT;
> +
> +	msg[0].addr = client->addr;
> +	msg[0].flags = client->flags;
> +	msg[0].len = 1;
> +	msg[0].buf = &addr;
> +
> +	msg[1].addr = client->addr;
> +	msg[1].flags = client->flags | I2C_M_RD;
> +	msg[1].len = len;
> +	msg[1].buf = data;
> +
> +	return i2c_transfer(client->adapter, msg, 2);
> +}
> +
> +static int hts221_i2c_write(struct device *dev, u8 addr, int len, u8 *data)
> +{
> +	u8 send[len + 1];
> +	struct i2c_msg msg;
> +	struct i2c_client *client = to_i2c_client(dev);
> +
> +	if (len > 1)
> +		addr |= I2C_AUTO_INCREMENT;
> +
> +	send[0] = addr;
> +	memcpy(&send[1], data, len * sizeof(u8));
> +
> +	msg.addr = client->addr;
> +	msg.flags = client->flags;
> +	msg.len = len + 1;
> +	msg.buf = send;
> +
> +	return i2c_transfer(client->adapter, &msg, 1);
> +}
> +
> +static const struct hts221_transfer_function hts221_transfer_fn = {
> +	.read = hts221_i2c_read,
> +	.write = hts221_i2c_write,
> +};
> +
> +static int hts221_i2c_probe(struct i2c_client *client,
> +			    const struct i2c_device_id *id)
> +{
> +	struct hts221_dev *dev;
> +	struct iio_dev *iio_dev;
> +
> +	iio_dev = devm_iio_device_alloc(&client->dev, sizeof(*dev));
> +	if (!iio_dev)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, iio_dev);
> +
> +	dev = iio_priv(iio_dev);
> +	dev->name = client->name;
> +	dev->dev = &client->dev;
> +	dev->irq = client->irq;
> +	dev->tf = &hts221_transfer_fn;
> +
> +	return hts221_probe(dev);
> +}
> +
> +static const struct of_device_id hts221_i2c_of_match[] = {
> +	{ .compatible = "st,hts221", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, hts221_i2c_of_match);
> +
> +static const struct i2c_device_id hts221_i2c_id_table[] = {
> +	{ HTS221_DEV_NAME },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(i2c, hts221_i2c_id_table);
> +
> +static struct i2c_driver hts221_driver = {
> +	.driver = {
> +		.name = "hts221_i2c",
> +		.of_match_table = of_match_ptr(hts221_i2c_of_match),
> +	},
> +	.probe = hts221_i2c_probe,
> +	.id_table = hts221_i2c_id_table,
> +};
> +module_i2c_driver(hts221_driver);
> +
> +MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>");
> +MODULE_DESCRIPTION("STMicroelectronics hts221 i2c driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/humidity/hts221/hts221_spi.c b/drivers/iio/humidity/hts221/hts221_spi.c
> new file mode 100644
> index 0000000..f128165
> --- /dev/null
> +++ b/drivers/iio/humidity/hts221/hts221_spi.c
> @@ -0,0 +1,125 @@
> +/*
> + * STMicroelectronics hts221 spi driver
> + *
> + * Copyright 2016 STMicroelectronics Inc.
> + *
> + * Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
> + *
> + * 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 *device, u8 addr, int len, u8 *data)
> +{
> +	int err;
> +	struct spi_device *spi = to_spi_device(device);
> +	struct iio_dev *iio_dev = spi_get_drvdata(spi);
> +	struct hts221_dev *dev = iio_priv(iio_dev);
> +
> +	struct spi_transfer xfers[] = {
> +		{
> +			.tx_buf = dev->tb.tx_buf,
> +			.bits_per_word = 8,
> +			.len = 1,
> +		},
> +		{
> +			.rx_buf = dev->tb.rx_buf,
> +			.bits_per_word = 8,
> +			.len = len,
> +		}
> +	};
> +
> +	if (len > 1)
> +		addr |= SPI_AUTO_INCREMENT;
> +	dev->tb.tx_buf[0] = addr | SENSORS_SPI_READ;
> +
> +	err = spi_sync_transfer(spi, xfers,  ARRAY_SIZE(xfers));
> +	if (err < 0)
> +		return err;
> +
> +	memcpy(data, dev->tb.rx_buf, len * sizeof(u8));
> +
> +	return len;
> +}
> +
> +static int hts221_spi_write(struct device *device, u8 addr, int len, u8 *data)
> +{
> +	struct spi_device *spi = to_spi_device(device);
> +	struct iio_dev *iio_dev = spi_get_drvdata(spi);
> +	struct hts221_dev *dev = iio_priv(iio_dev);
> +
> +	struct spi_transfer xfers = {
> +		.tx_buf = dev->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;
> +	dev->tb.tx_buf[0] = addr;
> +	memcpy(&dev->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_dev *dev;
I'd be tempted to rename this to something more specific (maybe
hts211_dev *hts221_instance or similar? You will probably come up with
something better than that!) as 'dev' is used extensively in
drivers for the struct device *dev pointer and this may prove
confusing when we come back to this driver in the future.

Same throughout the driver obviously!

> +	struct iio_dev *iio_dev;
> +
> +	iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*dev));
> +	if (!iio_dev)
> +		return -ENOMEM;
> +
> +	spi_set_drvdata(spi, iio_dev);
> +
> +	dev = iio_priv(iio_dev);
> +	dev->name = spi->modalias;
> +	dev->dev = &spi->dev;
> +	dev->irq = spi->irq;
> +	dev->tf = &hts221_transfer_fn;
> +
> +	return hts221_probe(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-qxv4g6HH51o@public.gmane.org>");
> +MODULE_DESCRIPTION("STMicroelectronics hts221 spi driver");
> +MODULE_LICENSE("GPL v2");
> 

--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH v3 2/2] Documentation: dt: iio: humidity: add hts221 sensor device binding

[Lorenzo Bianconi]

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
---
 .../devicetree/bindings/iio/humidity/hts221.txt       | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/humidity/hts221.txt

diff --git a/Documentation/devicetree/bindings/iio/humidity/hts221.txt b/Documentation/devicetree/bindings/iio/humidity/hts221.txt
new file mode 100644
index 0000000..46a152c
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/humidity/hts221.txt
@@ -0,0 +1,19 @@
+* HTS221 STM humidity + temperature sensor
+
+Required properties:
+- compatible: should be "st,hts221"
+- reg: i2c address of the sensor / spi cs line
+
+Optional properties:
+- interrupts: interrupt mapping for GPIO IRQ. It should be configured with
+	      flags IRQ_TYPE_LEVEL_HIGH or IRQ_TYPE_EDGE_RISING
+- interrupt-parent: should be the phandle for the interrupt controller
+
+Example:
+
+hts221@5f {
+	compatible = "st,hts221";
+	reg = <0x5f>;
+	interrupt-parent = <&gpio0>;
+	interrupts = <0 IRQ_TYPE_EDGE_RISING>;
+};
-- 
2.7.4

Re: [PATCH v3 2/2] Documentation: dt: iio: humidity: add hts221 sensor device binding

[Jonathan Cameron]

On 08/10/16 08:45, Lorenzo Bianconi wrote:
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi-qxv4g6HH51o@public.gmane.org>
> ---
>  .../devicetree/bindings/iio/humidity/hts221.txt       | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/humidity/hts221.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/humidity/hts221.txt b/Documentation/devicetree/bindings/iio/humidity/hts221.txt
> new file mode 100644
> index 0000000..46a152c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/humidity/hts221.txt
> @@ -0,0 +1,19 @@
> +* HTS221 STM humidity + temperature sensor
> +
> +Required properties:
> +- compatible: should be "st,hts221"
> +- reg: i2c address of the sensor / spi cs line
> +
> +Optional properties:
> +- interrupts: interrupt mapping for GPIO IRQ. It should be configured with
> +	      flags IRQ_TYPE_LEVEL_HIGH or IRQ_TYPE_EDGE_RISING
It might not be a gpio irq.  Plenty of IRQ only chips out there that you can't
use for general purpose reading (you can't explicitly read their state).

> +- interrupt-parent: should be the phandle for the interrupt controller
Convention here is to add a cross reference to the main interrupt docs.
We have been a bit lax on this in some IIO drivers but might as well be
good with a new one.

Otherwise this looks good to me.

Thanks,

Jonathan
> +
> +Example:
> +
> +hts221@5f {
> +	compatible = "st,hts221";
> +	reg = <0x5f>;
> +	interrupt-parent = <&gpio0>;
> +	interrupts = <0 IRQ_TYPE_EDGE_RISING>;
> +};
> 

--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html