IIO: Move the core files to drivers/iio

Take the core support + the kfifo buffer implentation out of
staging.  Whilst we are far from done in improving this subsystem
it is now at a stage where the userspae interfaces (provided by
the core) can be considered stable.

Drivers will follow over a longer time scale.

Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 755 insertions, 0 deletions

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
new file mode 100644
index 000000000000..b5b2c38045c5
--- /dev/null
+++ b/drivers/iio/industrialio-buffer.c
@@ -0,0 +1,755 @@
+/* The industrial I/O core
+ *
+ * Copyright (c) 2008 Jonathan Cameron
+ *
+ * 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.
+ *
+ * Handling of buffer allocation / resizing.
+ *
+ *
+ * Things to look at here.
+ * - Better memory allocation techniques?
+ * - Alternative access techniques?
+ */
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+
+#include <linux/iio/iio.h>
+#include "iio_core.h"
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+
+static const char * const iio_endian_prefix[] = {
+        [IIO_BE] = "be",
+        [IIO_LE] = "le",
+};
+
+/**
+ * iio_buffer_read_first_n_outer() - chrdev read for buffer access
+ *
+ * This function relies on all buffer implementations having an
+ * iio_buffer as their first element.
+ **/
+ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
+                                      size_t n, loff_t *f_ps)
+{
+        struct iio_dev *indio_dev = filp->private_data;
+        struct iio_buffer *rb = indio_dev->buffer;
+
+        if (!rb || !rb->access->read_first_n)
+                return -EINVAL;
+        return rb->access->read_first_n(rb, n, buf);
+}
+
+/**
+ * iio_buffer_poll() - poll the buffer to find out if it has data
+ */
+unsigned int iio_buffer_poll(struct file *filp,
+                             struct poll_table_struct *wait)
+{
+        struct iio_dev *indio_dev = filp->private_data;
+        struct iio_buffer *rb = indio_dev->buffer;
+
+        poll_wait(filp, &rb->pollq, wait);
+        if (rb->stufftoread)
+                return POLLIN | POLLRDNORM;
+        /* need a way of knowing if there may be enough data... */
+        return 0;
+}
+
+void iio_buffer_init(struct iio_buffer *buffer)
+{
+        INIT_LIST_HEAD(&buffer->demux_list);
+        init_waitqueue_head(&buffer->pollq);
+}
+EXPORT_SYMBOL(iio_buffer_init);
+
+static ssize_t iio_show_scan_index(struct device *dev,
+                                   struct device_attribute *attr,
+                                   char *buf)
+{
+        return sprintf(buf, "%u\n", to_iio_dev_attr(attr)->c->scan_index);
+}
+
+static ssize_t iio_show_fixed_type(struct device *dev,
+                                   struct device_attribute *attr,
+                                   char *buf)
+{
+        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+        u8 type = this_attr->c->scan_type.endianness;
+
+        if (type == IIO_CPU) {
+#ifdef __LITTLE_ENDIAN
+                type = IIO_LE;
+#else
+                type = IIO_BE;
+#endif
+        }
+        return sprintf(buf, "%s:%c%d/%d>>%u\n",
+                       iio_endian_prefix[type],
+                       this_attr->c->scan_type.sign,
+                       this_attr->c->scan_type.realbits,
+                       this_attr->c->scan_type.storagebits,
+                       this_attr->c->scan_type.shift);
+}
+
+static ssize_t iio_scan_el_show(struct device *dev,
+                                struct device_attribute *attr,
+                                char *buf)
+{
+        int ret;
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+
+        ret = test_bit(to_iio_dev_attr(attr)->address,
+                       indio_dev->buffer->scan_mask);
+
+        return sprintf(buf, "%d\n", ret);
+}
+
+static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
+{
+        clear_bit(bit, buffer->scan_mask);
+        return 0;
+}
+
+static ssize_t iio_scan_el_store(struct device *dev,
+                                 struct device_attribute *attr,
+                                 const char *buf,
+                                 size_t len)
+{
+        int ret;
+        bool state;
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+        struct iio_buffer *buffer = indio_dev->buffer;
+        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+
+        ret = strtobool(buf, &state);
+        if (ret < 0)
+                return ret;
+        mutex_lock(&indio_dev->mlock);
+        if (iio_buffer_enabled(indio_dev)) {
+                ret = -EBUSY;
+                goto error_ret;
+        }
+        ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
+        if (ret < 0)
+                goto error_ret;
+        if (!state && ret) {
+                ret = iio_scan_mask_clear(buffer, this_attr->address);
+                if (ret)
+                        goto error_ret;
+        } else if (state && !ret) {
+                ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
+                if (ret)
+                        goto error_ret;
+        }
+
+error_ret:
+        mutex_unlock(&indio_dev->mlock);
+
+        return ret < 0 ? ret : len;
+
+}
+
+static ssize_t iio_scan_el_ts_show(struct device *dev,
+                                   struct device_attribute *attr,
+                                   char *buf)
+{
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+        return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
+}
+
+static ssize_t iio_scan_el_ts_store(struct device *dev,
+                                    struct device_attribute *attr,
+                                    const char *buf,
+                                    size_t len)
+{
+        int ret;
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+        bool state;
+
+        ret = strtobool(buf, &state);
+        if (ret < 0)
+                return ret;
+
+        mutex_lock(&indio_dev->mlock);
+        if (iio_buffer_enabled(indio_dev)) {
+                ret = -EBUSY;
+                goto error_ret;
+        }
+        indio_dev->buffer->scan_timestamp = state;
+        indio_dev->scan_timestamp = state;
+error_ret:
+        mutex_unlock(&indio_dev->mlock);
+
+        return ret ? ret : len;
+}
+
+static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
+                                        const struct iio_chan_spec *chan)
+{
+        int ret, attrcount = 0;
+        struct iio_buffer *buffer = indio_dev->buffer;
+
+        ret = __iio_add_chan_devattr("index",
+                                     chan,
+                                     &iio_show_scan_index,
+                                     NULL,
+                                     0,
+                                     0,
+                                     &indio_dev->dev,
+                                     &buffer->scan_el_dev_attr_list);
+        if (ret)
+                goto error_ret;
+        attrcount++;
+        ret = __iio_add_chan_devattr("type",
+                                     chan,
+                                     &iio_show_fixed_type,
+                                     NULL,
+                                     0,
+                                     0,
+                                     &indio_dev->dev,
+                                     &buffer->scan_el_dev_attr_list);
+        if (ret)
+                goto error_ret;
+        attrcount++;
+        if (chan->type != IIO_TIMESTAMP)
+                ret = __iio_add_chan_devattr("en",
+                                             chan,
+                                             &iio_scan_el_show,
+                                             &iio_scan_el_store,
+                                             chan->scan_index,
+                                             0,
+                                             &indio_dev->dev,
+                                             &buffer->scan_el_dev_attr_list);
+        else
+                ret = __iio_add_chan_devattr("en",
+                                             chan,
+                                             &iio_scan_el_ts_show,
+                                             &iio_scan_el_ts_store,
+                                             chan->scan_index,
+                                             0,
+                                             &indio_dev->dev,
+                                             &buffer->scan_el_dev_attr_list);
+        attrcount++;
+        ret = attrcount;
+error_ret:
+        return ret;
+}
+
+static void iio_buffer_remove_and_free_scan_dev_attr(struct iio_dev *indio_dev,
+                                                     struct iio_dev_attr *p)
+{
+        kfree(p->dev_attr.attr.name);
+        kfree(p);
+}
+
+static void __iio_buffer_attr_cleanup(struct iio_dev *indio_dev)
+{
+        struct iio_dev_attr *p, *n;
+        struct iio_buffer *buffer = indio_dev->buffer;
+
+        list_for_each_entry_safe(p, n,
+                                 &buffer->scan_el_dev_attr_list, l)
+                iio_buffer_remove_and_free_scan_dev_attr(indio_dev, p);
+}
+
+static const char * const iio_scan_elements_group_name = "scan_elements";
+
+int iio_buffer_register(struct iio_dev *indio_dev,
+                        const struct iio_chan_spec *channels,
+                        int num_channels)
+{
+        struct iio_dev_attr *p;
+        struct attribute **attr;
+        struct iio_buffer *buffer = indio_dev->buffer;
+        int ret, i, attrn, attrcount, attrcount_orig = 0;
+
+        if (buffer->attrs)
+                indio_dev->groups[indio_dev->groupcounter++] = buffer->attrs;
+
+        if (buffer->scan_el_attrs != NULL) {
+                attr = buffer->scan_el_attrs->attrs;
+                while (*attr++ != NULL)
+                        attrcount_orig++;
+        }
+        attrcount = attrcount_orig;
+        INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
+        if (channels) {
+                /* new magic */
+                for (i = 0; i < num_channels; i++) {
+                        /* Establish necessary mask length */
+                        if (channels[i].scan_index >
+                            (int)indio_dev->masklength - 1)
+                                indio_dev->masklength
+                                        = indio_dev->channels[i].scan_index + 1;
+
+                        ret = iio_buffer_add_channel_sysfs(indio_dev,
+                                                         &channels[i]);
+                        if (ret < 0)
+                                goto error_cleanup_dynamic;
+                        attrcount += ret;
+                        if (channels[i].type == IIO_TIMESTAMP)
+                                indio_dev->scan_index_timestamp =
+                                        channels[i].scan_index;
+                }
+                if (indio_dev->masklength && buffer->scan_mask == NULL) {
+                        buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
+                                                    sizeof(*buffer->scan_mask),
+                                                    GFP_KERNEL);
+                        if (buffer->scan_mask == NULL) {
+                                ret = -ENOMEM;
+                                goto error_cleanup_dynamic;
+                        }
+                }
+        }
+
+        buffer->scan_el_group.name = iio_scan_elements_group_name;
+
+        buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
+                                              sizeof(buffer->scan_el_group.attrs[0]),
+                                              GFP_KERNEL);
+        if (buffer->scan_el_group.attrs == NULL) {
+                ret = -ENOMEM;
+                goto error_free_scan_mask;
+        }
+        if (buffer->scan_el_attrs)
+                memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
+                       sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
+        attrn = attrcount_orig;
+
+        list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
+                buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
+        indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
+
+        return 0;
+
+error_free_scan_mask:
+        kfree(buffer->scan_mask);
+error_cleanup_dynamic:
+        __iio_buffer_attr_cleanup(indio_dev);
+
+        return ret;
+}
+EXPORT_SYMBOL(iio_buffer_register);
+
+void iio_buffer_unregister(struct iio_dev *indio_dev)
+{
+        kfree(indio_dev->buffer->scan_mask);
+        kfree(indio_dev->buffer->scan_el_group.attrs);
+        __iio_buffer_attr_cleanup(indio_dev);
+}
+EXPORT_SYMBOL(iio_buffer_unregister);
+
+ssize_t iio_buffer_read_length(struct device *dev,
+                               struct device_attribute *attr,
+                               char *buf)
+{
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+        struct iio_buffer *buffer = indio_dev->buffer;
+
+        if (buffer->access->get_length)
+                return sprintf(buf, "%d\n",
+                               buffer->access->get_length(buffer));
+
+        return 0;
+}
+EXPORT_SYMBOL(iio_buffer_read_length);
+
+ssize_t iio_buffer_write_length(struct device *dev,
+                                struct device_attribute *attr,
+                                const char *buf,
+                                size_t len)
+{
+        int ret;
+        ulong val;
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+        struct iio_buffer *buffer = indio_dev->buffer;
+
+        ret = strict_strtoul(buf, 10, &val);
+        if (ret)
+                return ret;
+
+        if (buffer->access->get_length)
+                if (val == buffer->access->get_length(buffer))
+                        return len;
+
+        mutex_lock(&indio_dev->mlock);
+        if (iio_buffer_enabled(indio_dev)) {
+                ret = -EBUSY;
+        } else {
+                if (buffer->access->set_length)
+                        buffer->access->set_length(buffer, val);
+                ret = 0;
+        }
+        mutex_unlock(&indio_dev->mlock);
+
+        return ret ? ret : len;
+}
+EXPORT_SYMBOL(iio_buffer_write_length);
+
+ssize_t iio_buffer_store_enable(struct device *dev,
+                                struct device_attribute *attr,
+                                const char *buf,
+                                size_t len)
+{
+        int ret;
+        bool requested_state, current_state;
+        int previous_mode;
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+        struct iio_buffer *buffer = indio_dev->buffer;
+
+        mutex_lock(&indio_dev->mlock);
+        previous_mode = indio_dev->currentmode;
+        requested_state = !(buf[0] == '0');
+        current_state = iio_buffer_enabled(indio_dev);
+        if (current_state == requested_state) {
+                printk(KERN_INFO "iio-buffer, current state requested again\n");
+                goto done;
+        }
+        if (requested_state) {
+                if (indio_dev->setup_ops->preenable) {
+                        ret = indio_dev->setup_ops->preenable(indio_dev);
+                        if (ret) {
+                                printk(KERN_ERR
+                                       "Buffer not started:"
+                                       "buffer preenable failed\n");
+                                goto error_ret;
+                        }
+                }
+                if (buffer->access->request_update) {
+                        ret = buffer->access->request_update(buffer);
+                        if (ret) {
+                                printk(KERN_INFO
+                                       "Buffer not started:"
+                                       "buffer parameter update failed\n");
+                                goto error_ret;
+                        }
+                }
+                /* Definitely possible for devices to support both of these.*/
+                if (indio_dev->modes & INDIO_BUFFER_TRIGGERED) {
+                        if (!indio_dev->trig) {
+                                printk(KERN_INFO
+                                       "Buffer not started: no trigger\n");
+                                ret = -EINVAL;
+                                goto error_ret;
+                        }
+                        indio_dev->currentmode = INDIO_BUFFER_TRIGGERED;
+                } else if (indio_dev->modes & INDIO_BUFFER_HARDWARE)
+                        indio_dev->currentmode = INDIO_BUFFER_HARDWARE;
+                else { /* should never be reached */
+                        ret = -EINVAL;
+                        goto error_ret;
+                }
+
+                if (indio_dev->setup_ops->postenable) {
+                        ret = indio_dev->setup_ops->postenable(indio_dev);
+                        if (ret) {
+                                printk(KERN_INFO
+                                       "Buffer not started:"
+                                       "postenable failed\n");
+                                indio_dev->currentmode = previous_mode;
+                                if (indio_dev->setup_ops->postdisable)
+                                        indio_dev->setup_ops->
+                                                postdisable(indio_dev);
+                                goto error_ret;
+                        }
+                }
+        } else {
+                if (indio_dev->setup_ops->predisable) {
+                        ret = indio_dev->setup_ops->predisable(indio_dev);
+                        if (ret)
+                                goto error_ret;
+                }
+                indio_dev->currentmode = INDIO_DIRECT_MODE;
+                if (indio_dev->setup_ops->postdisable) {
+                        ret = indio_dev->setup_ops->postdisable(indio_dev);
+                        if (ret)
+                                goto error_ret;
+                }
+        }
+done:
+        mutex_unlock(&indio_dev->mlock);
+        return len;
+
+error_ret:
+        mutex_unlock(&indio_dev->mlock);
+        return ret;
+}
+EXPORT_SYMBOL(iio_buffer_store_enable);
+
+ssize_t iio_buffer_show_enable(struct device *dev,
+                               struct device_attribute *attr,
+                               char *buf)
+{
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+        return sprintf(buf, "%d\n", iio_buffer_enabled(indio_dev));
+}
+EXPORT_SYMBOL(iio_buffer_show_enable);
+
+/* note NULL used as error indicator as it doesn't make sense. */
+static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
+                                          unsigned int masklength,
+                                          const unsigned long *mask)
+{
+        if (bitmap_empty(mask, masklength))
+                return NULL;
+        while (*av_masks) {
+                if (bitmap_subset(mask, av_masks, masklength))
+                        return av_masks;
+                av_masks += BITS_TO_LONGS(masklength);
+        }
+        return NULL;
+}
+
+static int iio_compute_scan_bytes(struct iio_dev *indio_dev, const long *mask,
+                                  bool timestamp)
+{
+        const struct iio_chan_spec *ch;
+        unsigned bytes = 0;
+        int length, i;
+
+        /* How much space will the demuxed element take? */
+        for_each_set_bit(i, mask,
+                         indio_dev->masklength) {
+                ch = iio_find_channel_from_si(indio_dev, i);
+                length = ch->scan_type.storagebits / 8;
+                bytes = ALIGN(bytes, length);
+                bytes += length;
+        }
+        if (timestamp) {
+                ch = iio_find_channel_from_si(indio_dev,
+                                              indio_dev->scan_index_timestamp);
+                length = ch->scan_type.storagebits / 8;
+                bytes = ALIGN(bytes, length);
+                bytes += length;
+        }
+        return bytes;
+}
+
+int iio_sw_buffer_preenable(struct iio_dev *indio_dev)
+{
+        struct iio_buffer *buffer = indio_dev->buffer;
+        dev_dbg(&indio_dev->dev, "%s\n", __func__);
+
+        /* How much space will the demuxed element take? */
+        indio_dev->scan_bytes =
+                iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
+                                       buffer->scan_timestamp);
+        buffer->access->set_bytes_per_datum(buffer, indio_dev->scan_bytes);
+
+        /* What scan mask do we actually have ?*/
+        if (indio_dev->available_scan_masks)
+                indio_dev->active_scan_mask =
+                        iio_scan_mask_match(indio_dev->available_scan_masks,
+                                            indio_dev->masklength,
+                                            buffer->scan_mask);
+        else
+                indio_dev->active_scan_mask = buffer->scan_mask;
+        iio_update_demux(indio_dev);
+
+        if (indio_dev->info->update_scan_mode)
+                return indio_dev->info
+                        ->update_scan_mode(indio_dev,
+                                           indio_dev->active_scan_mask);
+        return 0;
+}
+EXPORT_SYMBOL(iio_sw_buffer_preenable);
+
+/**
+ * iio_scan_mask_set() - set particular bit in the scan mask
+ * @buffer: the buffer whose scan mask we are interested in
+ * @bit: the bit to be set.
+ **/
+int iio_scan_mask_set(struct iio_dev *indio_dev,
+                      struct iio_buffer *buffer, int bit)
+{
+        const unsigned long *mask;
+        unsigned long *trialmask;
+
+        trialmask = kmalloc(sizeof(*trialmask)*
+                            BITS_TO_LONGS(indio_dev->masklength),
+                            GFP_KERNEL);
+
+        if (trialmask == NULL)
+                return -ENOMEM;
+        if (!indio_dev->masklength) {
+                WARN_ON("trying to set scanmask prior to registering buffer\n");
+                kfree(trialmask);
+                return -EINVAL;
+        }
+        bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
+        set_bit(bit, trialmask);
+
+        if (indio_dev->available_scan_masks) {
+                mask = iio_scan_mask_match(indio_dev->available_scan_masks,
+                                           indio_dev->masklength,
+                                           trialmask);
+                if (!mask) {
+                        kfree(trialmask);
+                        return -EINVAL;
+                }
+        }
+        bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
+
+        kfree(trialmask);
+
+        return 0;
+};
+EXPORT_SYMBOL_GPL(iio_scan_mask_set);
+
+int iio_scan_mask_query(struct iio_dev *indio_dev,
+                        struct iio_buffer *buffer, int bit)
+{
+        if (bit > indio_dev->masklength)
+                return -EINVAL;
+
+        if (!buffer->scan_mask)
+                return 0;
+
+        return test_bit(bit, buffer->scan_mask);
+};
+EXPORT_SYMBOL_GPL(iio_scan_mask_query);
+
+/**
+ * struct iio_demux_table() - table describing demux memcpy ops
+ * @from:       index to copy from
+ * @to: index to copy to
+ * @length:     how many bytes to copy
+ * @l:          list head used for management
+ */
+struct iio_demux_table {
+        unsigned from;
+        unsigned to;
+        unsigned length;
+        struct list_head l;
+};
+
+static unsigned char *iio_demux(struct iio_buffer *buffer,
+                                 unsigned char *datain)
+{
+        struct iio_demux_table *t;
+
+        if (list_empty(&buffer->demux_list))
+                return datain;
+        list_for_each_entry(t, &buffer->demux_list, l)
+                memcpy(buffer->demux_bounce + t->to,
+                       datain + t->from, t->length);
+
+        return buffer->demux_bounce;
+}
+
+int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data,
+                       s64 timestamp)
+{
+        unsigned char *dataout = iio_demux(buffer, data);
+
+        return buffer->access->store_to(buffer, dataout, timestamp);
+}
+EXPORT_SYMBOL_GPL(iio_push_to_buffer);
+
+static void iio_buffer_demux_free(struct iio_buffer *buffer)
+{
+        struct iio_demux_table *p, *q;
+        list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
+                list_del(&p->l);
+                kfree(p);
+        }
+}
+
+int iio_update_demux(struct iio_dev *indio_dev)
+{
+        const struct iio_chan_spec *ch;
+        struct iio_buffer *buffer = indio_dev->buffer;
+        int ret, in_ind = -1, out_ind, length;
+        unsigned in_loc = 0, out_loc = 0;
+        struct iio_demux_table *p;
+
+        /* Clear out any old demux */
+        iio_buffer_demux_free(buffer);
+        kfree(buffer->demux_bounce);
+        buffer->demux_bounce = NULL;
+
+        /* First work out which scan mode we will actually have */
+        if (bitmap_equal(indio_dev->active_scan_mask,
+                         buffer->scan_mask,
+                         indio_dev->masklength))
+                return 0;
+
+        /* Now we have the two masks, work from least sig and build up sizes */
+        for_each_set_bit(out_ind,
+                         indio_dev->active_scan_mask,
+                         indio_dev->masklength) {
+                in_ind = find_next_bit(indio_dev->active_scan_mask,
+                                       indio_dev->masklength,
+                                       in_ind + 1);
+                while (in_ind != out_ind) {
+                        in_ind = find_next_bit(indio_dev->active_scan_mask,
+                                               indio_dev->masklength,
+                                               in_ind + 1);
+                        ch = iio_find_channel_from_si(indio_dev, in_ind);
+                        length = ch->scan_type.storagebits/8;
+                        /* Make sure we are aligned */
+                        in_loc += length;
+                        if (in_loc % length)
+                                in_loc += length - in_loc % length;
+                }
+                p = kmalloc(sizeof(*p), GFP_KERNEL);
+                if (p == NULL) {
+                        ret = -ENOMEM;
+                        goto error_clear_mux_table;
+                }
+                ch = iio_find_channel_from_si(indio_dev, in_ind);
+                length = ch->scan_type.storagebits/8;
+                if (out_loc % length)
+                        out_loc += length - out_loc % length;
+                if (in_loc % length)
+                        in_loc += length - in_loc % length;
+                p->from = in_loc;
+                p->to = out_loc;
+                p->length = length;
+                list_add_tail(&p->l, &buffer->demux_list);
+                out_loc += length;
+                in_loc += length;
+        }
+        /* Relies on scan_timestamp being last */
+        if (buffer->scan_timestamp) {
+                p = kmalloc(sizeof(*p), GFP_KERNEL);
+                if (p == NULL) {
+                        ret = -ENOMEM;
+                        goto error_clear_mux_table;
+                }
+                ch = iio_find_channel_from_si(indio_dev,
+                        indio_dev->scan_index_timestamp);
+                length = ch->scan_type.storagebits/8;
+                if (out_loc % length)
+                        out_loc += length - out_loc % length;
+                if (in_loc % length)
+                        in_loc += length - in_loc % length;
+                p->from = in_loc;
+                p->to = out_loc;
+                p->length = length;
+                list_add_tail(&p->l, &buffer->demux_list);
+                out_loc += length;
+                in_loc += length;
+        }
+        buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
+        if (buffer->demux_bounce == NULL) {
+                ret = -ENOMEM;
+                goto error_clear_mux_table;
+        }
+        return 0;
+
+error_clear_mux_table:
+        iio_buffer_demux_free(buffer);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(iio_update_demux);