On 17/11/16 21:48, Peter Rosin wrote:
> When a multiplexer changes how an iio device behaves (for example
> by feeding different signals to an ADC), this driver can be used
> create one virtual iio channel for each multiplexer state.
>
> Depends on the generic multiplexer driver.
I'm not really following what all the ext info stuff in here is about.
Could you add a little more description of that?
Perhaps an example of how it is used and what the resulting interface
looks like?
Thanks,
Jonathan
> ---
> drivers/iio/Kconfig | 1 +
> drivers/iio/Makefile | 1 +
> drivers/iio/multiplexer/Kconfig | 17 ++
> drivers/iio/multiplexer/Makefile | 6 +
> drivers/iio/multiplexer/iio-mux.c | 444
> ++++++++++++++++++++++++++++++++++++++
> 5 files changed, 469 insertions(+)
> create mode 100644 drivers/iio/multiplexer/Kconfig
> create mode 100644 drivers/iio/multiplexer/Makefile
> create mode 100644 drivers/iio/multiplexer/iio-mux.c
>
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 6743b18194fb..dcb541d0d70e 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -82,6 +82,7 @@ source "drivers/iio/humidity/Kconfig"
> source "drivers/iio/imu/Kconfig"
> source "drivers/iio/light/Kconfig"
> source "drivers/iio/magnetometer/Kconfig"
> +source "drivers/iio/multiplexer/Kconfig"
> source "drivers/iio/orientation/Kconfig"
> if IIO_TRIGGER
> source "drivers/iio/trigger/Kconfig"
> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
> index 87e4c4369e2f..f9879c29cf6f 100644
> --- a/drivers/iio/Makefile
> +++ b/drivers/iio/Makefile
> @@ -27,6 +27,7 @@ obj-y += humidity/
> obj-y += imu/
> obj-y += light/
> obj-y += magnetometer/
> +obj-y += multiplexer/
> obj-y += orientation/
> obj-y += potentiometer/
> obj-y += pressure/
> diff --git a/drivers/iio/multiplexer/Kconfig b/drivers/iio/multiplexer/Kconfig
> new file mode 100644
> index 000000000000..31cbe4509366
> --- /dev/null
> +++ b/drivers/iio/multiplexer/Kconfig
> @@ -0,0 +1,17 @@
> +#
> +# Multiplexer drivers
> +#
> +# When adding new entries keep the list in alphabetical order
> +
> +menu "Multiplexers"
> +
> +config IIO_MUX
> + tristate "IIO multiplexer driver"
> + depends on OF && MUX_GPIO
> + help
> + Say yes here to build support for the IIO multiplexer.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called iio-mux.
> +
> +endmenu
> diff --git a/drivers/iio/multiplexer/Makefile
> b/drivers/iio/multiplexer/Makefile
> new file mode 100644
> index 000000000000..68be3c4abd07
> --- /dev/null
> +++ b/drivers/iio/multiplexer/Makefile
> @@ -0,0 +1,6 @@
> +#
> +# Makefile for industrial I/O multiplexer drivers
> +#
> +
> +# When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_IIO_MUX) += iio-mux.o
> diff --git a/drivers/iio/multiplexer/iio-mux.c
> b/drivers/iio/multiplexer/iio-mux.c
> new file mode 100644
> index 000000000000..2a8d00da990b
> --- /dev/null
> +++ b/drivers/iio/multiplexer/iio-mux.c
> @@ -0,0 +1,444 @@
> +/*
> + * IIO multiplexer driver
> + *
> + * Copyright (C) 2016 Axentia Technologies AB
> + *
> + * Author: Peter Rosin <p...@axentia.se>
> + *
> + * 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.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/iio/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/mux.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +
> +struct mux_ext_info_cache {
> + char *data;
> + size_t size;
> +};
> +
> +struct mux_child {
> + u32 state;
> +
> + struct mux_ext_info_cache *ext_info_cache;
> +};
> +
> +struct mux {
> + u32 cached_state;
> + struct mux_control *control;
> + struct iio_channel *parent;
> + struct iio_dev *indio_dev;
> + struct iio_chan_spec *c;
> + struct iio_chan_spec_ext_info *ext_info;
> + struct mux_child *child;
> +};
> +
> +static int iio_mux_select(struct mux *mux, int idx)
> +{
> + struct mux_child *child = &mux->child[idx];
> + int ret;
> + int i;
> +
> + ret = mux_control_select(mux->control, child->state);
> + if (ret < 0) {
> + mux->cached_state = -1;
> + return ret;
> + }
> +
> + if (mux->cached_state == child->state)
> + return 0;
> +
I don't follow what is going on here.. Perhaps you could explain
futher?
> + if (mux->c[idx].ext_info) {
> + for (i = 0; mux->c[idx].ext_info[i].name; ++i) {
> + const char *attr = mux->c[idx].ext_info[i].name;
> + struct mux_ext_info_cache *cache;
> +
> + cache = &child->ext_info_cache[i];
> +
> + if (cache->size < 0)
> + continue;
> +
> + ret = iio_write_channel_ext_info(mux->parent, attr,
> + cache->data,
> + cache->size);
> +
> + if (ret < 0) {
> + mux_control_deselect(mux->control);
> + mux->cached_state = -1;
> + return ret;
> + }
> + }
> + }
> + mux->cached_state = child->state;
> +
> + return 0;
> +}
> +
> +static void iio_mux_deselect(struct mux *mux)
> +{
> + mux_control_deselect(mux->control);
> +}
> +
> +static int mux_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct mux *mux = iio_priv(indio_dev);
> + int idx = chan - mux->c;
> + int ret;
> +
> + ret = iio_mux_select(mux, idx);
> + if (ret < 0)
> + return ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = iio_read_channel_raw(mux->parent, val);
> + break;
> +
> + case IIO_CHAN_INFO_SCALE:
> + ret = iio_read_channel_scale(mux->parent, val, val2);
> + break;
> +
> + default:
> + ret = -EINVAL;
> + }
> +
> + iio_mux_deselect(mux);
> +
> + return ret;
> +}
> +
> +static int mux_read_avail(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + const int **vals, int *type, int *length,
> + long mask)
> +{
> + struct mux *mux = iio_priv(indio_dev);
> + int idx = chan - mux->c;
> + int ret;
> +
> + ret = iio_mux_select(mux, idx);
> + if (ret < 0)
> + return ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + *type = IIO_VAL_INT;
> + ret = iio_read_avail_channel_raw(mux->parent, vals, length);
> + break;
> +
> + default:
> + ret = -EINVAL;
> + }
> +
> + iio_mux_deselect(mux);
> +
> + return ret;
> +}
> +
> +static int mux_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct mux *mux = iio_priv(indio_dev);
> + int idx = chan - mux->c;
> + int ret;
> +
> + ret = iio_mux_select(mux, idx);
> + if (ret < 0)
> + return ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = iio_write_channel_raw(mux->parent, val);
> + break;
> +
> + default:
> + ret = -EINVAL;
> + }
> +
> + iio_mux_deselect(mux);
> +
> + return ret;
> +}
> +
> +static const struct iio_info mux_info = {
> + .read_raw = mux_read_raw,
> + .read_avail = mux_read_avail,
> + .write_raw = mux_write_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static ssize_t mux_read_ext_info(struct iio_dev *indio_dev, uintptr_t
> private,
> + struct iio_chan_spec const *chan, char *buf)
> +{
> + struct mux *mux = iio_priv(indio_dev);
> + int idx = chan - mux->c;
> + ssize_t ret;
> +
> + ret = iio_mux_select(mux, idx);
> + if (ret < 0)
> + return ret;
> +
> + ret = iio_read_channel_ext_info(mux->parent,
> + mux->ext_info[private].name,
> + buf);
> +
> + iio_mux_deselect(mux);
> +
> + return ret;
> +}
> +
> +static ssize_t mux_write_ext_info(struct iio_dev *indio_dev, uintptr_t
> private,
> + struct iio_chan_spec const *chan,
> + const char *buf, size_t len)
> +{
> + struct device *dev = indio_dev->dev.parent;
> + struct mux *mux = iio_priv(indio_dev);
> + int idx = chan - mux->c;
> + char *new;
> + ssize_t ret;
> +
> + ret = iio_mux_select(mux, idx);
> + if (ret < 0)
> + return ret;
> +
> + new = devm_kmemdup(dev, buf, len + 1, GFP_KERNEL);
> + if (!new) {
> + iio_mux_deselect(mux);
> + return -ENOMEM;
> + }
> +
> + new[len] = 0;
> +
> + ret = iio_write_channel_ext_info(mux->parent,
> + mux->ext_info[private].name,
> + buf, len);
> + if (ret < 0) {
> + iio_mux_deselect(mux);
> + devm_kfree(dev, new);
> + return ret;
> + }
> +
> + devm_kfree(dev, mux->child[idx].ext_info_cache[private].data);
> + mux->child[idx].ext_info_cache[private].data = new;
> + mux->child[idx].ext_info_cache[private].size = len;
> +
> + iio_mux_deselect(mux);
> +
> + return ret;
> +}
> +
> +static int mux_configure_channel(struct device *dev, struct mux *mux,
> + struct device_node *child_np, int idx)
> +{
> + struct mux_child *child = &mux->child[idx];
> + struct iio_chan_spec *c = &mux->c[idx];
> + const struct iio_chan_spec *pc = mux->parent->channel;
> + char *page;
> + int num_ext_info;
> + int i;
> + int ret;
> +
> + c->indexed = 1;
> + c->channel = idx;
> + c->output = pc->output;
> + c->datasheet_name = child_np->name;
> + c->ext_info = mux->ext_info;
> +
> + ret = iio_get_channel_type(mux->parent, &c->type);
> + if (ret < 0) {
> + dev_err(dev, "failed to get parent channel type\n");
> + return ret;
> + }
> +
> + if (iio_channel_has_info(pc, IIO_CHAN_INFO_RAW))
> + c->info_mask_separate |= BIT(IIO_CHAN_INFO_RAW);
> + if (iio_channel_has_info(pc, IIO_CHAN_INFO_SCALE))
> + c->info_mask_separate |= BIT(IIO_CHAN_INFO_SCALE);
> +
> + if (iio_channel_has_available(pc, IIO_CHAN_INFO_RAW))
> + c->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW);
> +
> + ret = of_property_read_u32(child_np, "reg", &child->state);
> + if (ret < 0) {
> + dev_err(dev, "no reg property for node '%s'\n", child_np->name);
> + return ret;
> + }
> +
> + for (i = 0; i < idx; ++i) {
> + if (mux->child[i].state == child->state) {
> + dev_err(dev, "double use of reg %d\n", child->state);
> + return -EINVAL;
> + }
> + }
> +
> + num_ext_info = iio_get_channel_ext_info_count(mux->parent);
> + if (num_ext_info) {
> + page = devm_kzalloc(dev, PAGE_SIZE, GFP_KERNEL);
> + if (!page)
> + return -ENOMEM;
> + }
> + child->ext_info_cache = devm_kzalloc(dev,
> + sizeof(*child->ext_info_cache) *
> + num_ext_info, GFP_KERNEL);
> + for (i = 0; i < num_ext_info; ++i) {
> + child->ext_info_cache[i].size = -1;
> +
> + if (!pc->ext_info[i].write)
> + continue;
> + if (!pc->ext_info[i].read)
> + continue;
> +
> + ret = iio_read_channel_ext_info(mux->parent,
> + mux->ext_info[i].name,
> + page);
> + if (ret < 0) {
> + dev_err(dev, "failed to get ext_info '%s'\n",
> + pc->ext_info[i].name);
> + return ret;
> + }
> + if (ret >= PAGE_SIZE) {
> + dev_err(dev, "too large ext_info '%s'\n",
> + pc->ext_info[i].name);
> + return -EINVAL;
> + }
> +
> + child->ext_info_cache[i].data = devm_kmemdup(dev, page, ret + 1,
> + GFP_KERNEL);
> + child->ext_info_cache[i].data[ret] = 0;
> + child->ext_info_cache[i].size = ret;
> + }
> +
> + if (num_ext_info)
> + devm_kfree(dev, page);
> +
> + return 0;
> +}
> +
> +static int mux_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *np = pdev->dev.of_node;
> + struct device_node *child_np;
> + struct iio_dev *indio_dev;
> + struct iio_channel *parent;
> + struct mux *mux;
> + int sizeof_ext_info;
> + int children;
> + int sizeof_priv;
> + int i;
> + int ret;
> +
> + if (!np)
> + return -ENODEV;
> +
> + parent = devm_iio_channel_get(dev, "parent");
> + if (IS_ERR(parent)) {
> + if (PTR_ERR(parent) != -EPROBE_DEFER)
> + dev_err(dev, "failed to get parent channel\n");
> + return PTR_ERR(parent);
> + }
> +
> + sizeof_ext_info = iio_get_channel_ext_info_count(parent);
> + if (sizeof_ext_info) {
> + sizeof_ext_info += 1; /* one extra entry for the sentinel */
> + sizeof_ext_info *= sizeof(*mux->ext_info);
> + }
> +
> + children = of_get_child_count(np);
> + if (children <= 0) {
> + dev_err(dev, "not even a single child\n");
> + return -EINVAL;
> + }
> +
> + sizeof_priv = sizeof(*mux);
> + sizeof_priv += sizeof(*mux->child) * children;
> + sizeof_priv += sizeof(*mux->c) * children;
> + sizeof_priv += sizeof_ext_info;
> +
> + indio_dev = devm_iio_device_alloc(dev, sizeof_priv);
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + mux = iio_priv(indio_dev);
> + mux->child = (struct mux_child *)(mux + 1);
> + mux->c = (struct iio_chan_spec *)(mux->child + children);
> +
> + platform_set_drvdata(pdev, indio_dev);
> +
> + mux->parent = parent;
> + mux->cached_state = -1;
> +
> + indio_dev->name = dev_name(dev);
> + indio_dev->dev.parent = dev;
> + indio_dev->info = &mux_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = mux->c;
> + indio_dev->num_channels = children;
> + if (sizeof_ext_info) {
> + mux->ext_info = devm_kmemdup(dev,
> + parent->channel->ext_info,
> + sizeof_ext_info, GFP_KERNEL);
> + if (!mux->ext_info)
> + return -ENOMEM;
> +
> + for (i = 0; mux->ext_info[i].name; ++i) {
> + if (parent->channel->ext_info[i].read)
> + mux->ext_info[i].read = mux_read_ext_info;
> + if (parent->channel->ext_info[i].write)
> + mux->ext_info[i].write = mux_write_ext_info;
> + mux->ext_info[i].private = i;
> + }
> + }
> +
> + i = 0;
> + for_each_child_of_node(np, child_np) {
> + ret = mux_configure_channel(dev, mux, child_np, i);
> + if (ret < 0)
> + return ret;
> + i++;
> + }
> +
> + mux->control = devm_mux_control_get(dev, "mux");
> + if (IS_ERR(mux->control)) {
> + if (PTR_ERR(mux->control) != -EPROBE_DEFER)
> + dev_err(dev, "failed to get control-mux\n");
> + return PTR_ERR(mux->control);
> + }
> +
> + ret = devm_iio_device_register(dev, indio_dev);
> + if (ret) {
> + dev_err(dev, "failed to register iio device\n");
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static const struct of_device_id mux_match[] = {
> + { .compatible = "iio-mux" },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, mux_match);
> +
> +static struct platform_driver mux_driver = {
> + .probe = mux_probe,
> + .driver = {
> + .name = "iio-mux",
> + .of_match_table = mux_match,
> + },
> +};
> +module_platform_driver(mux_driver);
> +
> +MODULE_DESCRIPTION("IIO multiplexer driver");
> +MODULE_AUTHOR("Peter Rosin <p...@axentia.se>");
> +MODULE_LICENSE("GPL v2");
>
