Merge tag 'iio-for-3.14b' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-next

Jonathan writes:

2nd round of new IIO drivers, features and cleanups for the 3.14 cycle.

New drivers

* HID inclinometer driver.

* DHT11 humidity driver.  Note that previous humidity drivers have been in
  hwmon, but no one was ever entirely happy with that, and they should find
  a more comfortable home in IIO (their original placement in hwmon was my
  fault - oops).  As this is our first humidity driver, core support is also
  added.

New features

* Two of mxs-lradc channels are internally wired to a temperature sensor,
  make this explicit in the driver by providing the relevant temperature
  channel.

* Add support for blocking IO on buffers.

* Add a data_available call back to the interface between buffer implementations
  and the core.  This is much cleaner than the old, 'stufftoread' flag.
  Implemented in the kfifo buffer.

Cleanups

* Last user of the old event configuration interface is converted and the
  old interface dropped.  Nice to be rid of this thanks to Lars-Peter's hard
  work!

* Replace all remaining instances of the IIO_ST macro with explicit filling
  of the scan_type structure within struct iio_chan_spec.  This macro was a
  bad idea, that rapidly ceased to cover all elements of the structure.
  Miss reading of the macro arguements has led to a number of bugs so lets
  just get rid of it. The final removal patch is awaiting for some fixes
  to make their way into mainline.
  In a couple of drivers, no elements of scan_type were even being used so
  in those case, it has been dropped entirely.

* Drop a couple of of_match_ptr helper uses in drivers where devicetree is
  not optional and hence the structures being protected by this always exist.

* Fix up some cases where data was read from a device in a particular
  byte order, but he code placed it into a s16 or similar.  These were
  highlighted by Sparse.

* Use the new ATTRIBUTE_GROUPS macro to drop some boiler plate in the triggers
  core code.

* ad7746 and ad7280a - stop storing buffers on the stack, giving cleaner code
  and possibly avoiding issues with i2c bus drivers that assume they can dma
  directly into the buffer.  Note that this cannot currently happen as the the
  i2c_smbus_read_i2c_block_data function has a memcpy from the buffer actually
  passed to the bus driver.  I missed this element of the commit message
  and don't think it is major enough to rebase the iio tree.

* ad5791 and ad5504 stop storing buffers on the stack for an SPI driver.
  Unlike the i2c drivers, this is a real issue for SPI drivers which can dma
  directly into the buffer supplied.

1 files changed, 294 insertions, 0 deletions

diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
new file mode 100644
index 0000000..d8771f5
--- /dev/null
+++ b/drivers/iio/humidity/dht11.c
@@ -0,0 +1,294 @@
+/*
+ * DHT11/DHT22 bit banging GPIO driver
+ *
+ * Copyright (c) Harald Geyer <harald@ccbib.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/sysfs.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/wait.h>
+#include <linux/bitops.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+
+#include <linux/iio/iio.h>
+
+#define DRIVER_NAME	"dht11"
+
+#define DHT11_DATA_VALID_TIME	2000000000  /* 2s in ns */
+
+#define DHT11_EDGES_PREAMBLE 4
+#define DHT11_BITS_PER_READ 40
+#define DHT11_EDGES_PER_READ (2*DHT11_BITS_PER_READ + DHT11_EDGES_PREAMBLE + 1)
+
+/* Data transmission timing (nano seconds) */
+#define DHT11_START_TRANSMISSION	18  /* ms */
+#define DHT11_SENSOR_RESPONSE	80000
+#define DHT11_START_BIT		50000
+#define DHT11_DATA_BIT_LOW	27000
+#define DHT11_DATA_BIT_HIGH	70000
+
+struct dht11 {
+	struct device			*dev;
+
+	int				gpio;
+	int				irq;
+
+	struct completion		completion;
+
+	s64				timestamp;
+	int				temperature;
+	int				humidity;
+
+	/* num_edges: -1 means "no transmission in progress" */
+	int				num_edges;
+	struct {s64 ts; int value; }	edges[DHT11_EDGES_PER_READ];
+};
+
+static unsigned char dht11_decode_byte(int *timing, int threshold)
+{
+	unsigned char ret = 0;
+	int i;
+
+	for (i = 0; i < 8; ++i) {
+		ret <<= 1;
+		if (timing[i] >= threshold)
+			++ret;
+	}
+
+	return ret;
+}
+
+static int dht11_decode(struct dht11 *dht11, int offset)
+{
+	int i, t, timing[DHT11_BITS_PER_READ], threshold,
+		timeres = DHT11_SENSOR_RESPONSE;
+	unsigned char temp_int, temp_dec, hum_int, hum_dec, checksum;
+
+	/* Calculate timestamp resolution */
+	for (i = 0; i < dht11->num_edges; ++i) {
+		t = dht11->edges[i].ts - dht11->edges[i-1].ts;
+		if (t > 0 && t < timeres)
+			timeres = t;
+	}
+	if (2*timeres > DHT11_DATA_BIT_HIGH) {
+		pr_err("dht11: timeresolution %d too bad for decoding\n",
+			timeres);
+		return -EIO;
+	}
+	threshold = DHT11_DATA_BIT_HIGH / timeres;
+	if (DHT11_DATA_BIT_LOW/timeres + 1 >= threshold)
+		pr_err("dht11: WARNING: decoding ambiguous\n");
+
+	/* scale down with timeres and check validity */
+	for (i = 0; i < DHT11_BITS_PER_READ; ++i) {
+		t = dht11->edges[offset + 2*i + 2].ts -
+			dht11->edges[offset + 2*i + 1].ts;
+		if (!dht11->edges[offset + 2*i + 1].value)
+			return -EIO;  /* lost synchronisation */
+		timing[i] = t / timeres;
+	}
+
+	hum_int = dht11_decode_byte(timing, threshold);
+	hum_dec = dht11_decode_byte(&timing[8], threshold);
+	temp_int = dht11_decode_byte(&timing[16], threshold);
+	temp_dec = dht11_decode_byte(&timing[24], threshold);
+	checksum = dht11_decode_byte(&timing[32], threshold);
+
+	if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum)
+		return -EIO;
+
+	dht11->timestamp = iio_get_time_ns();
+	if (hum_int < 20) {  /* DHT22 */
+		dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *
+					((temp_int & 0x80) ? -100 : 100);
+		dht11->humidity = ((hum_int << 8) + hum_dec) * 100;
+	} else if (temp_dec == 0 && hum_dec == 0) {  /* DHT11 */
+		dht11->temperature = temp_int * 1000;
+		dht11->humidity = hum_int * 1000;
+	} else {
+		dev_err(dht11->dev,
+			"Don't know how to decode data: %d %d %d %d\n",
+			hum_int, hum_dec, temp_int, temp_dec);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int dht11_read_raw(struct iio_dev *iio_dev,
+			const struct iio_chan_spec *chan,
+			int *val, int *val2, long m)
+{
+	struct dht11 *dht11 = iio_priv(iio_dev);
+	int ret;
+
+	if (dht11->timestamp + DHT11_DATA_VALID_TIME < iio_get_time_ns()) {
+		reinit_completion(&dht11->completion);
+
+		dht11->num_edges = 0;
+		ret = gpio_direction_output(dht11->gpio, 0);
+		if (ret)
+			goto err;
+		msleep(DHT11_START_TRANSMISSION);
+		ret = gpio_direction_input(dht11->gpio);
+		if (ret)
+			goto err;
+
+		ret = wait_for_completion_killable_timeout(&dht11->completion,
+								 HZ);
+		if (ret == 0 && dht11->num_edges < DHT11_EDGES_PER_READ - 1) {
+			dev_err(&iio_dev->dev,
+					"Only %d signal edges detected\n",
+					dht11->num_edges);
+			ret = -ETIMEDOUT;
+		}
+		if (ret < 0)
+			goto err;
+
+		ret = dht11_decode(dht11,
+				dht11->num_edges == DHT11_EDGES_PER_READ ?
+					DHT11_EDGES_PREAMBLE :
+					DHT11_EDGES_PREAMBLE - 2);
+		if (ret)
+			goto err;
+	}
+
+	ret = IIO_VAL_INT;
+	if (chan->type == IIO_TEMP)
+		*val = dht11->temperature;
+	else if (chan->type == IIO_HUMIDITYRELATIVE)
+		*val = dht11->humidity;
+	else
+		ret = -EINVAL;
+err:
+	dht11->num_edges = -1;
+	return ret;
+}
+
+static const struct iio_info dht11_iio_info = {
+	.driver_module		= THIS_MODULE,
+	.read_raw		= dht11_read_raw,
+};
+
+/*
+ * IRQ handler called on GPIO edges
+*/
+static irqreturn_t dht11_handle_irq(int irq, void *data)
+{
+	struct iio_dev *iio = data;
+	struct dht11 *dht11 = iio_priv(iio);
+
+	/* TODO: Consider making the handler safe for IRQ sharing */
+	if (dht11->num_edges < DHT11_EDGES_PER_READ && dht11->num_edges >= 0) {
+		dht11->edges[dht11->num_edges].ts = iio_get_time_ns();
+		dht11->edges[dht11->num_edges++].value =
+						gpio_get_value(dht11->gpio);
+
+		if (dht11->num_edges >= DHT11_EDGES_PER_READ)
+			complete(&dht11->completion);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static const struct iio_chan_spec dht11_chan_spec[] = {
+	{ .type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), },
+	{ .type = IIO_HUMIDITYRELATIVE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), }
+};
+
+static const struct of_device_id dht11_dt_ids[] = {
+	{ .compatible = "dht11", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, dht11_dt_ids);
+
+static int dht11_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
+	struct dht11 *dht11;
+	struct iio_dev *iio;
+	int ret;
+
+	iio = devm_iio_device_alloc(dev, sizeof(*dht11));
+	if (!iio) {
+		dev_err(dev, "Failed to allocate IIO device\n");
+		return -ENOMEM;
+	}
+
+	dht11 = iio_priv(iio);
+	dht11->dev = dev;
+
+	dht11->gpio = ret = of_get_gpio(node, 0);
+	if (ret < 0)
+		return ret;
+	ret = devm_gpio_request_one(dev, dht11->gpio, GPIOF_IN, pdev->name);
+	if (ret)
+		return ret;
+
+	dht11->irq = gpio_to_irq(dht11->gpio);
+	if (dht11->irq < 0) {
+		dev_err(dev, "GPIO %d has no interrupt\n", dht11->gpio);
+		return -EINVAL;
+	}
+	ret = devm_request_irq(dev, dht11->irq, dht11_handle_irq,
+				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+				pdev->name, iio);
+	if (ret)
+		return ret;
+
+	dht11->timestamp = iio_get_time_ns() - DHT11_DATA_VALID_TIME - 1;
+	dht11->num_edges = -1;
+
+	platform_set_drvdata(pdev, iio);
+
+	init_completion(&dht11->completion);
+	iio->name = pdev->name;
+	iio->dev.parent = &pdev->dev;
+	iio->info = &dht11_iio_info;
+	iio->modes = INDIO_DIRECT_MODE;
+	iio->channels = dht11_chan_spec;
+	iio->num_channels = ARRAY_SIZE(dht11_chan_spec);
+
+	return devm_iio_device_register(dev, iio);
+}
+
+static struct platform_driver dht11_driver = {
+	.driver = {
+		.name	= DRIVER_NAME,
+		.owner	= THIS_MODULE,
+		.of_match_table = dht11_dt_ids,
+	},
+	.probe  = dht11_probe,
+};
+
+module_platform_driver(dht11_driver);
+
+MODULE_AUTHOR("Harald Geyer <harald@ccbib.org>");
+MODULE_DESCRIPTION("DHT11 humidity/temperature sensor driver");
+MODULE_LICENSE("GPL v2");