1 files changed, 348 insertions, 0 deletions
diff --git a/drivers/staging/iio/accel/sca3000_ring.c b/drivers/staging/iio/accel/sca3000_ring.c
new file mode 100644
index 000000000..8589eade1
--- /dev/null
+++ b/drivers/staging/iio/accel/sca3000_ring.c
@@ -0,0 +1,348 @@
+/*
+ * sca3000_ring.c -- support VTI sca3000 series accelerometers via SPI
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * Copyright (c) 2009 Jonathan Cameron <jic23@kernel.org>
+ *
+ */
+
+#include <linux/interrupt.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/spi/spi.h>
+#include <linux/sysfs.h>
+#include <linux/sched.h>
+#include <linux/poll.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include "../ring_hw.h"
+#include "sca3000.h"
+
+/* RFC / future work
+ *
+ * The internal ring buffer doesn't actually change what it holds depending
+ * on which signals are enabled etc, merely whether you can read them.
+ * As such the scan mode selection is somewhat different than for a software
+ * ring buffer and changing it actually covers any data already in the buffer.
+ * Currently scan elements aren't configured so it doesn't matter.
+ */
+
+static int sca3000_read_data(struct sca3000_state *st,
+			    uint8_t reg_address_high,
+			    u8 **rx_p,
+			    int len)
+{
+	int ret;
+	struct spi_transfer xfer[2] = {
+		{
+			.len = 1,
+			.tx_buf = st->tx,
+		}, {
+			.len = len,
+		}
+	};
+	*rx_p = kmalloc(len, GFP_KERNEL);
+	if (*rx_p == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	xfer[1].rx_buf = *rx_p;
+	st->tx[0] = SCA3000_READ_REG(reg_address_high);
+	ret = spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
+	if (ret) {
+		dev_err(get_device(&st->us->dev), "problem reading register");
+		goto error_free_rx;
+	}
+
+	return 0;
+error_free_rx:
+	kfree(*rx_p);
+error_ret:
+	return ret;
+}
+
+/**
+ * sca3000_read_first_n_hw_rb() - main ring access, pulls data from ring
+ * @r:			the ring
+ * @count:		number of samples to try and pull
+ * @data:		output the actual samples pulled from the hw ring
+ *
+ * Currently does not provide timestamps.  As the hardware doesn't add them they
+ * can only be inferred approximately from ring buffer events such as 50% full
+ * and knowledge of when buffer was last emptied.  This is left to userspace.
+ **/
+static int sca3000_read_first_n_hw_rb(struct iio_buffer *r,
+				      size_t count, char __user *buf)
+{
+	struct iio_hw_buffer *hw_ring = iio_to_hw_buf(r);
+	struct iio_dev *indio_dev = hw_ring->private;
+	struct sca3000_state *st = iio_priv(indio_dev);
+	u8 *rx;
+	int ret, i, num_available, num_read = 0;
+	int bytes_per_sample = 1;
+
+	if (st->bpse == 11)
+		bytes_per_sample = 2;
+
+	mutex_lock(&st->lock);
+	if (count % bytes_per_sample) {
+		ret = -EINVAL;
+		goto error_ret;
+	}
+
+	ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_BUF_COUNT, 1);
+	if (ret)
+		goto error_ret;
+	else
+		num_available = st->rx[0];
+	/*
+	 * num_available is the total number of samples available
+	 * i.e. number of time points * number of channels.
+	 */
+	if (count > num_available * bytes_per_sample)
+		num_read = num_available*bytes_per_sample;
+	else
+		num_read = count;
+
+	ret = sca3000_read_data(st,
+				SCA3000_REG_ADDR_RING_OUT,
+				&rx, num_read);
+	if (ret)
+		goto error_ret;
+
+	for (i = 0; i < num_read; i++)
+		*(((u16 *)rx) + i) = be16_to_cpup((__be16 *)rx + i);
+
+	if (copy_to_user(buf, rx, num_read))
+		ret = -EFAULT;
+	kfree(rx);
+	r->stufftoread = 0;
+error_ret:
+	mutex_unlock(&st->lock);
+
+	return ret ? ret : num_read;
+}
+
+static size_t sca3000_ring_buf_data_available(struct iio_buffer *r)
+{
+	return r->stufftoread ? r->watermark : 0;
+}
+
+/**
+ * sca3000_query_ring_int() is the hardware ring status interrupt enabled
+ **/
+static ssize_t sca3000_query_ring_int(struct device *dev,
+				      struct device_attribute *attr,
+				      char *buf)
+{
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	int ret, val;
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct sca3000_state *st = iio_priv(indio_dev);
+
+	mutex_lock(&st->lock);
+	ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_INT_MASK, 1);
+	val = st->rx[0];
+	mutex_unlock(&st->lock);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "%d\n", !!(val & this_attr->address));
+}
+
+/**
+ * sca3000_set_ring_int() set state of ring status interrupt
+ **/
+static ssize_t sca3000_set_ring_int(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf,
+				      size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct sca3000_state *st = iio_priv(indio_dev);
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	u8 val;
+	int ret;
+
+	mutex_lock(&st->lock);
+	ret = kstrtou8(buf, 10, &val);
+	if (ret)
+		goto error_ret;
+	ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_INT_MASK, 1);
+	if (ret)
+		goto error_ret;
+	if (val)
+		ret = sca3000_write_reg(st,
+					SCA3000_REG_ADDR_INT_MASK,
+					st->rx[0] | this_attr->address);
+	else
+		ret = sca3000_write_reg(st,
+					SCA3000_REG_ADDR_INT_MASK,
+					st->rx[0] & ~this_attr->address);
+error_ret:
+	mutex_unlock(&st->lock);
+
+	return ret ? ret : len;
+}
+
+static IIO_DEVICE_ATTR(50_percent, S_IRUGO | S_IWUSR,
+		       sca3000_query_ring_int,
+		       sca3000_set_ring_int,
+		       SCA3000_INT_MASK_RING_HALF);
+
+static IIO_DEVICE_ATTR(75_percent, S_IRUGO | S_IWUSR,
+		       sca3000_query_ring_int,
+		       sca3000_set_ring_int,
+		       SCA3000_INT_MASK_RING_THREE_QUARTER);
+
+static ssize_t sca3000_show_buffer_scale(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct sca3000_state *st = iio_priv(indio_dev);
+
+	return sprintf(buf, "0.%06d\n", 4*st->info->scale);
+}
+
+static IIO_DEVICE_ATTR(in_accel_scale,
+		       S_IRUGO,
+		       sca3000_show_buffer_scale,
+		       NULL,
+		       0);
+
+/*
+ * Ring buffer attributes
+ * This device is a bit unusual in that the sampling frequency and bpse
+ * only apply to the ring buffer.  At all times full rate and accuracy
+ * is available via direct reading from registers.
+ */
+static const struct attribute *sca3000_ring_attributes[] = {
+	&iio_dev_attr_50_percent.dev_attr.attr,
+	&iio_dev_attr_75_percent.dev_attr.attr,
+	&iio_dev_attr_in_accel_scale.dev_attr.attr,
+	NULL,
+};
+
+static struct iio_buffer *sca3000_rb_allocate(struct iio_dev *indio_dev)
+{
+	struct iio_buffer *buf;
+	struct iio_hw_buffer *ring;
+
+	ring = kzalloc(sizeof(*ring), GFP_KERNEL);
+	if (!ring)
+		return NULL;
+
+	ring->private = indio_dev;
+	buf = &ring->buf;
+	buf->stufftoread = 0;
+	buf->length = 64;
+	buf->attrs = sca3000_ring_attributes;
+	iio_buffer_init(buf);
+
+	return buf;
+}
+
+static void sca3000_ring_release(struct iio_buffer *r)
+{
+	kfree(iio_to_hw_buf(r));
+}
+
+static const struct iio_buffer_access_funcs sca3000_ring_access_funcs = {
+	.read_first_n = &sca3000_read_first_n_hw_rb,
+	.data_available = sca3000_ring_buf_data_available,
+	.release = sca3000_ring_release,
+};
+
+int sca3000_configure_ring(struct iio_dev *indio_dev)
+{
+	struct iio_buffer *buffer;
+
+	buffer = sca3000_rb_allocate(indio_dev);
+	if (buffer == NULL)
+		return -ENOMEM;
+	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
+
+	indio_dev->buffer->access = &sca3000_ring_access_funcs;
+
+	iio_device_attach_buffer(indio_dev, buffer);
+
+	return 0;
+}
+
+void sca3000_unconfigure_ring(struct iio_dev *indio_dev)
+{
+	iio_buffer_put(indio_dev->buffer);
+}
+
+static inline
+int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&st->lock);
+	ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_MODE, 1);
+	if (ret)
+		goto error_ret;
+	if (state) {
+		dev_info(&indio_dev->dev, "supposedly enabling ring buffer\n");
+		ret = sca3000_write_reg(st,
+					SCA3000_REG_ADDR_MODE,
+					(st->rx[0] | SCA3000_RING_BUF_ENABLE));
+	} else
+		ret = sca3000_write_reg(st,
+					SCA3000_REG_ADDR_MODE,
+					(st->rx[0] & ~SCA3000_RING_BUF_ENABLE));
+error_ret:
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+/**
+ * sca3000_hw_ring_preenable() hw ring buffer preenable function
+ *
+ * Very simple enable function as the chip will allows normal reads
+ * during ring buffer operation so as long as it is indeed running
+ * before we notify the core, the precise ordering does not matter.
+ **/
+static int sca3000_hw_ring_preenable(struct iio_dev *indio_dev)
+{
+	return __sca3000_hw_ring_state_set(indio_dev, 1);
+}
+
+static int sca3000_hw_ring_postdisable(struct iio_dev *indio_dev)
+{
+	return __sca3000_hw_ring_state_set(indio_dev, 0);
+}
+
+static const struct iio_buffer_setup_ops sca3000_ring_setup_ops = {
+	.preenable = &sca3000_hw_ring_preenable,
+	.postdisable = &sca3000_hw_ring_postdisable,
+};
+
+void sca3000_register_ring_funcs(struct iio_dev *indio_dev)
+{
+	indio_dev->setup_ops = &sca3000_ring_setup_ops;
+}
+
+/**
+ * sca3000_ring_int_process() ring specific interrupt handling.
+ *
+ * This is only split from the main interrupt handler so as to
+ * reduce the amount of code if the ring buffer is not enabled.
+ **/
+void sca3000_ring_int_process(u8 val, struct iio_buffer *ring)
+{
+	if (val & (SCA3000_INT_STATUS_THREE_QUARTERS |
+		   SCA3000_INT_STATUS_HALF)) {
+		ring->stufftoread = true;
+		wake_up_interruptible(&ring->pollq);
+	}
+}