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    SubjectRe: [PATCH 5/6] IIO:hwmon interface client driver.
    On Wed, Oct 19, 2011 at 10:47:07AM -0400, Jonathan Cameron wrote:
    > Should move to drivers/hwmon once people are happy with it.
    >
    > Minimal support of simple in, curr and temp attributes
    > so far.
    >
    > Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>

    Couple of comments below.

    > ---
    > drivers/iio/Kconfig | 8 ++
    > drivers/iio/Makefile | 1 +
    > drivers/iio/iio_hwmon.c | 214 +++++++++++++++++++++++++++++++++++++++++++++++
    > 3 files changed, 223 insertions(+), 0 deletions(-)
    >
    > diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
    > index 308bc97..fb6d0a1 100644
    > --- a/drivers/iio/Kconfig
    > +++ b/drivers/iio/Kconfig
    > @@ -11,6 +11,14 @@ menuconfig IIO
    >
    > if IIO
    >
    > +config IIO_HWMON
    > + tristate "Hwmon driver that uses channels specified via iio maps"
    > + help
    > + This is a platform driver that in combination with a suitable
    > + map allows IIO devices to provide basic hwmon functionality
    > + for those channels specified in the map.
    > +
    Should probably also depend on HWMON

    > +
    > source "drivers/iio/adc/Kconfig"
    > source "drivers/iio/imu/Kconfig"
    > source "drivers/iio/light/Kconfig"
    > diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
    > index cfb588a..5f9c01a 100644
    > --- a/drivers/iio/Makefile
    > +++ b/drivers/iio/Makefile
    > @@ -6,6 +6,7 @@ obj-y = inkern.o
    > obj-$(CONFIG_IIO) += iio.o
    > industrialio-y := core.o
    >
    > +obj-$(CONFIG_IIO_HWMON) += iio_hwmon.o
    > obj-y += adc/
    > obj-y += imu/
    > obj-y += light/
    > diff --git a/drivers/iio/iio_hwmon.c b/drivers/iio/iio_hwmon.c
    > new file mode 100644
    > index 0000000..6eeceeb
    > --- /dev/null
    > +++ b/drivers/iio/iio_hwmon.c
    > @@ -0,0 +1,214 @@
    > +/* Hwmon client for industrial I/O devices
    > + *
    > + * Copyright (c) 2011 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.
    > + *
    > + * Limited functionality currently supported.
    > + */
    > +
    > +#include <linux/kernel.h>
    > +#include <linux/slab.h>
    > +#include <linux/module.h>
    > +#include <linux/err.h>
    > +#include <linux/platform_device.h>
    > +#include <linux/iio/inkern.h>
    > +#include <linux/hwmon.h>
    > +#include <linux/hwmon-sysfs.h>
    > +
    > +/**
    > + * struct iio_hwmon_state - device instance state
    > + * @channels: filled with null terminated array of channels from iio
    > + * @num_channels: number of channels in channels (saves counting twice)
    > + * @hwmon_dev: associated hwmon device
    > + * @attr_group: the group of attributes
    > + * @attrs: null terminated array of attribute pointers.
    > + */
    > +struct iio_hwmon_state {
    > + struct iio_channel **channels;
    > + int num_channels;
    > + struct device *hwmon_dev;
    > + struct attribute_group attr_group;
    > + struct attribute **attrs;
    > +};
    > +
    > +/*
    > + * Assumes that IIO and hwmon operate in the same base units.
    > + * This is supposed to be true, but needs verification for
    > + * new channel types.
    > + */
    > +static ssize_t iio_hwmon_read_val(struct device *dev,
    > + struct device_attribute *attr,
    > + char *buf)
    > +{
    > + long result;
    > + int val, ret, scaleint, scalepart;
    > + struct sensor_device_attribute *sattr =
    > + to_sensor_dev_attr(attr);

    Does this need more than one line ?

    > + struct iio_hwmon_state *state = dev_get_drvdata(dev);
    > +
    > + /*
    > + * No locking between this pair, so theoretically possible
    > + * the scale has changed.
    > + */
    > + ret = iio_read_channel_raw(state->channels[sattr->index],
    > + &val);
    > + if (ret < 0)
    > + return ret;
    > +
    > + ret = iio_read_channel_scale(state->channels[sattr->index],
    > + &scaleint, &scalepart);
    > + if (ret < 0)
    > + return ret;
    > + switch (ret) {
    > + case IIO_VAL_INT:
    > + result = val * scaleint;
    > + break;
    > + case IIO_VAL_INT_PLUS_MICRO:
    > + result = val * (scaleint * 1000000 + scalepart)/1000000;
    > + break;
    > + case IIO_VAL_INT_PLUS_NANO:
    > + result = val * (scaleint * 1000000000 + scalepart)/1000000000;

    I think you might want to use long or even long long for all variables here,
    or at least typecast to long or long long. Concern is that for example
    "scaleint * 1000000000" may be calculated as int and would easily overflow;
    even as long it would easily overflow.

    There should be blanks around '/' (why doesn't checkpatch complain about this anymore ?).

    > + break;
    > + default:
    > + return -EINVAL;
    > + }
    > + return sprintf(buf, "%ld\n", result);
    > +}
    > +
    > +static void iio_hwmon_free_attrs(struct iio_hwmon_state *st)
    > +{
    > + int i;
    > + struct sensor_device_attribute *a;
    > + for (i = 0; i < st->num_channels; i++)
    > + if (st->attrs[i]) {
    > + a = to_sensor_dev_attr(
    > + container_of(st->attrs[i],
    > + struct device_attribute,
    > + attr));
    > + kfree(a);
    > + }
    > +}
    > +
    > +static int __devinit iio_hwmon_probe(struct platform_device *pdev)
    > +{
    > + struct iio_hwmon_state *st;
    > + struct sensor_device_attribute *a;
    > + int ret, i = 0;
    > + int in_i = 1, temp_i = 1, curr_i = 1;
    > +
    > + st = kzalloc(sizeof(*st), GFP_KERNEL);
    > + if (st == NULL) {
    > + ret = -ENOMEM;
    > + goto error_ret;
    > + }
    > +
    > + st->channels = iio_channel_get_all(&pdev->dev, NULL);
    > + if (IS_ERR(st->channels)) {
    > + ret = PTR_ERR(st->channels);
    > + goto error_free_state;
    > + }
    > +
    > + /* count how many attributes we have */
    > + while (st->channels[st->num_channels])
    > + st->num_channels++;
    > +
    > + st->attrs = kzalloc(sizeof(st->attrs)*(i+1), GFP_KERNEL);

    Blanks around '*' and '+'.
    i == 0 here, so what is the point, and what are you trying to do ?
    Should it be st->num_channels instead of i + 1 ?

    > + if (st->attrs == NULL) {
    > + ret = -ENOMEM;
    > + goto error_release_channels;
    > + }
    > + for (i = 0; i < st->num_channels; i++) {
    > + a = kzalloc(sizeof(*a), GFP_KERNEL);

    What if this fails ?

    > + sysfs_attr_init(&a->dev_attr.attr);
    > + switch (iio_get_channel_type(st->channels[i])) {
    > + case IIO_VOLTAGE:
    > + a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
    > + "in%d_input",
    > + in_i++);
    > + break;
    > + case IIO_TEMP:
    > + a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
    > + "temp%d_input",
    > + temp_i++);
    > + break;
    > + case IIO_CURRENT:
    > + a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
    > + "curr%d_input",
    > + curr_i++);
    > + break;
    > + default:
    > + ret = -EINVAL;
    > + goto error_free_attrs;
    > + }
    > + if (a->dev_attr.attr.name == NULL) {
    > + ret = -ENOMEM;
    > + goto error_free_attrs;
    > + }
    I think this and the above EINVAL will result in leaking "a" since you did not store it
    in st->attrs[i] yet.

    > + a->dev_attr.show = iio_hwmon_read_val;
    > + a->dev_attr.attr.mode = S_IRUGO;
    > + a->index = i;
    > + st->attrs[i] = &a->dev_attr.attr;
    > + }
    > +
    > + st->attr_group.attrs = st->attrs;
    > + st->hwmon_dev = hwmon_device_register(&pdev->dev);
    > +
    Would be better to do this after successfully creating the sysfs attributes.

    > + ret = sysfs_create_group(&pdev->dev.kobj, &st->attr_group);
    > + if (ret < 0)
    > + goto error_free_attrs;
    > +
    > + platform_set_drvdata(pdev, st);
    > +
    You need to do this prior to creating the sysfs entries, since the read functions
    expect it to be there.

    > + return 0;
    > +
    > +error_free_attrs:

    This doesn't unregister the hwmon device.

    > + iio_hwmon_free_attrs(st);
    > + kfree(st->attrs);
    > +error_release_channels:
    > + iio_channel_release_all(st->channels);
    > +error_free_state:
    > + kfree(st);
    > +error_ret:
    > + return ret;
    > +}
    > +
    > +static int __devexit iio_hwmon_remove(struct platform_device *pdev)
    > +{
    > + struct iio_hwmon_state *st = platform_get_drvdata(pdev);
    > +
    > + sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
    > + iio_hwmon_free_attrs(st);
    > + kfree(st->attrs);
    > + hwmon_device_unregister(st->hwmon_dev);
    > + iio_channel_release_all(st->channels);
    > +
    > + return 0;
    > +}
    > +
    > +static struct platform_driver __refdata iio_hwmon_driver = {
    > + .driver = {
    > + .name = "iio_hwmon",
    > + .owner = THIS_MODULE,
    > + },
    > + .probe = iio_hwmon_probe,
    > + .remove = __devexit_p(iio_hwmon_remove),
    > +};
    > +
    > +static int iio_inkern_init(void)
    > +{
    > + return platform_driver_register(&iio_hwmon_driver);
    > +}
    > +module_init(iio_inkern_init);
    > +
    > +static void iio_inkern_exit(void)
    > +{
    > + platform_driver_unregister(&iio_hwmon_driver);
    > +}
    > +module_exit(iio_inkern_exit);
    > +
    > +MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
    > +MODULE_DESCRIPTION("IIO to hwmon driver");
    > +MODULE_LICENSE("GPL v2");
    > --
    > 1.7.7
    >

    --
    Guenter Roeck
    Distinguished Engineer
    PDU IP Systems


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