iio: mxc4005: add triggered buffer mode for mxc4005

This patch adds support for buffered readings for the 3-axis
accelerometer mxc4005.
Signed-off-by: Teodora Baluta <teodora.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/Kconfig

@@ -140,6 +140,8 @@ config MMA9553
 config MXC4005
 	tristate "Memsic MXC4005XC 3-Axis Accelerometer Driver"
 	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
 	select REGMAP_I2C
 	help
 	  Say yes here to build support for the Memsic MXC4005XC 3-axis

drivers/iio/accel/mxc4005.c

@@ -19,6 +19,9 @@
 #include <linux/acpi.h>
 #include <linux/regmap.h>
 #include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
 
 #define MXC4005_DRV_NAME		"mxc4005"
 #define MXC4005_REGMAP_NAME		"mxc4005_regmap"
@@ -52,6 +55,7 @@ struct mxc4005_data {
 	struct device *dev;
 	struct mutex mutex;
 	struct regmap *regmap;
+	__be16 buffer[8];
 };
 
 /*
@@ -122,6 +126,20 @@ static const struct regmap_config mxc4005_regmap_config = {
 	.writeable_reg = mxc4005_is_writeable_reg,
 };
 
+static int mxc4005_read_xyz(struct mxc4005_data *data)
+{
+	int ret;
+
+	ret = regmap_bulk_read(data->regmap, MXC4005_REG_XOUT_UPPER,
+			       (u8 *) data->buffer, sizeof(data->buffer));
+	if (ret < 0) {
+		dev_err(data->dev, "failed to read axes\n");
+		return ret;
+	}
+
+	return 0;
+}
+
 static int mxc4005_read_axis(struct mxc4005_data *data,
 			     unsigned int addr)
 {
@@ -197,7 +215,8 @@ static int mxc4005_read_raw(struct iio_dev *indio_dev,
 			ret = mxc4005_read_axis(data, chan->address);
 			if (ret < 0)
 				return ret;
-			*val = sign_extend32(ret >> 4, 11);
+			*val = sign_extend32(ret >> chan->scan_type.shift,
+					     chan->scan_type.realbits - 1);
 			return IIO_VAL_INT;
 		default:
 			return -EINVAL;
@@ -239,6 +258,11 @@ static const struct iio_info mxc4005_info = {
 	.attrs		= &mxc4005_attrs_group,
 };
 
+static const unsigned long mxc4005_scan_masks[] = {
+	BIT(AXIS_X) | BIT(AXIS_Y) | BIT(AXIS_Z),
+	0
+};
+
 #define MXC4005_CHANNEL(_axis, _addr) {				\
 	.type = IIO_ACCEL,					\
 	.modified = 1,						\
@@ -246,14 +270,43 @@ static const struct iio_info mxc4005_info = {
 	.address = _addr,					\
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+	.scan_index = AXIS_##_axis,				\
+	.scan_type = {						\
+		.sign = 's',					\
+		.realbits = 12,					\
+		.storagebits = 16,				\
+		.shift = 4,					\
+		.endianness = IIO_BE,				\
+	},							\
 }
 
 static const struct iio_chan_spec mxc4005_channels[] = {
 	MXC4005_CHANNEL(X, MXC4005_REG_XOUT_UPPER),
 	MXC4005_CHANNEL(Y, MXC4005_REG_YOUT_UPPER),
 	MXC4005_CHANNEL(Z, MXC4005_REG_ZOUT_UPPER),
+	IIO_CHAN_SOFT_TIMESTAMP(3),
 };
 
+static irqreturn_t mxc4005_trigger_handler(int irq, void *private)
+{
+	struct iio_poll_func *pf = private;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct mxc4005_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = mxc4005_read_xyz(data);
+	if (ret < 0)
+		goto err;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+					   pf->timestamp);
+
+err:
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
 static int mxc4005_chip_init(struct mxc4005_data *data)
 {
 	int ret;
@@ -304,23 +357,43 @@ static int mxc4005_probe(struct i2c_client *client,
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->channels = mxc4005_channels;
 	indio_dev->num_channels = ARRAY_SIZE(mxc4005_channels);
+	indio_dev->available_scan_masks = mxc4005_scan_masks;
 	indio_dev->name = MXC4005_DRV_NAME;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &mxc4005_info;
 
+	ret = iio_triggered_buffer_setup(indio_dev,
+					 &iio_pollfunc_store_time,
+					 mxc4005_trigger_handler,
+					 NULL);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"failed to setup iio triggered buffer\n");
+		return ret;
+	}
+
 	ret = iio_device_register(indio_dev);
 	if (ret < 0) {
 		dev_err(&client->dev,
 			"unable to register iio device %d\n", ret);
-		return ret;
+		goto err_buffer_cleanup;
 	}
 
 	return 0;
+
+err_buffer_cleanup:
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	return ret;
 }
 
 static int mxc4005_remove(struct i2c_client *client)
 {
-	iio_device_unregister(i2c_get_clientdata(client));
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+
+	iio_triggered_buffer_cleanup(indio_dev);
 
 	return 0;
 }