iio:accel: Add STMicroelectronics accelerometers driver

This patch adds a generic accelerometer driver for STMicroelectronics
accelerometers, currently it supports:
LSM303DLH, LSM303DLHC, LIS3DH, LSM330D, LSM330DL, LSM330DLC,
LIS331DLH, LSM303DL, LSM303DLM, LSM330.

Signed-off-by: Denis Ciocca <denis.ciocca@st.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/st_accel_buffer.c

@@ -0,0 +1,114 @@
+/*
+ * STMicroelectronics accelerometers driver
+ *
+ * Copyright 2012-2013 STMicroelectronics Inc.
+ *
+ * Denis Ciocca <denis.ciocca@st.com>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#include <linux/iio/common/st_sensors.h>
+#include "st_accel.h"
+
+int st_accel_trig_set_state(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *indio_dev = trig->private_data;
+
+	return st_sensors_set_dataready_irq(indio_dev, state);
+}
+
+static int st_accel_buffer_preenable(struct iio_dev *indio_dev)
+{
+	int err;
+
+	err = st_sensors_set_enable(indio_dev, true);
+	if (err < 0)
+		goto st_accel_set_enable_error;
+
+	err = iio_sw_buffer_preenable(indio_dev);
+
+st_accel_set_enable_error:
+	return err;
+}
+
+static int st_accel_buffer_postenable(struct iio_dev *indio_dev)
+{
+	int err;
+	struct st_sensor_data *adata = iio_priv(indio_dev);
+
+	adata->buffer_data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
+	if (adata->buffer_data == NULL) {
+		err = -ENOMEM;
+		goto allocate_memory_error;
+	}
+
+	err = st_sensors_set_axis_enable(indio_dev,
+					(u8)indio_dev->active_scan_mask[0]);
+	if (err < 0)
+		goto st_accel_buffer_postenable_error;
+
+	err = iio_triggered_buffer_postenable(indio_dev);
+	if (err < 0)
+		goto st_accel_buffer_postenable_error;
+
+	return err;
+
+st_accel_buffer_postenable_error:
+	kfree(adata->buffer_data);
+allocate_memory_error:
+	return err;
+}
+
+static int st_accel_buffer_predisable(struct iio_dev *indio_dev)
+{
+	int err;
+	struct st_sensor_data *adata = iio_priv(indio_dev);
+
+	err = iio_triggered_buffer_predisable(indio_dev);
+	if (err < 0)
+		goto st_accel_buffer_predisable_error;
+
+	err = st_sensors_set_axis_enable(indio_dev, ST_SENSORS_ENABLE_ALL_AXIS);
+	if (err < 0)
+		goto st_accel_buffer_predisable_error;
+
+	err = st_sensors_set_enable(indio_dev, false);
+
+st_accel_buffer_predisable_error:
+	kfree(adata->buffer_data);
+	return err;
+}
+
+static const struct iio_buffer_setup_ops st_accel_buffer_setup_ops = {
+	.preenable = &st_accel_buffer_preenable,
+	.postenable = &st_accel_buffer_postenable,
+	.predisable = &st_accel_buffer_predisable,
+};
+
+int st_accel_allocate_ring(struct iio_dev *indio_dev)
+{
+	return iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
+		&st_sensors_trigger_handler, &st_accel_buffer_setup_ops);
+}
+
+void st_accel_deallocate_ring(struct iio_dev *indio_dev)
+{
+	iio_triggered_buffer_cleanup(indio_dev);
+}
+
+MODULE_AUTHOR("Denis Ciocca <denis.ciocca@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics accelerometers buffer");
+MODULE_LICENSE("GPL v2");