On Thu, 21 Jul 2022 20:15:24 +0100
Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote:
> The IIO_AVAIL_LIST_WITH_TYPE specifies that the array that corresponds
> to the available values is composed by cells of 3 integers, the first
> two representing the value itself (similar to what you would have with
> IIO_AVAIL_LIST), and the third integer representing the encoding type of
> the value.
>
> This can be used for instance when a driver's .read_avail() callback
> returns values which cannot be represented with an unique encoding type.
>
> Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
Hi Paul,
Generally looks good to me, but I'm not sure the overflow checks will work
as expected.
Jonathan
> ---
> drivers/iio/industrialio-core.c | 25 +++++++++++++++++++++++++
> drivers/iio/inkern.c | 23 +++++++++++++++++++++++
> include/linux/iio/consumer.h | 6 ++++--
> include/linux/iio/types.h | 1 +
> 4 files changed, 53 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index adf054c7a75e..99ced9eab069 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -838,6 +838,29 @@ static ssize_t iio_format_avail_range(char *buf, const int *vals, int type)
> return iio_format_list(buf, vals, type, 3, "[", "]");
> }
>
> +static ssize_t iio_format_avail_list_with_type(char *buf, const int *vals,
> + int length)
> +{
> + ssize_t len = 0;
> + int i;
> +
> + for (i = 0; i < length; i += 3) {
> + if (i != 0) {
> + len += sysfs_emit_at(buf, len, " ");
> + if (len >= PAGE_SIZE)
I don't think this check will trigger if I read the sysfs_emit_at() docs right.
> + return -EFBIG;
> + }
> +
> + len += __iio_format_value(buf, len, vals[i + 2], 2, &vals[i]);
> + if (len >= PAGE_SIZE)
Can this trigger? sysfs_emit_at() inside __iio_format_value() will only return
characters written which I think is none if there isn't space left in the page...
I think the normal thing to do is to just not handle the overflow if it occurs...
> + return -EFBIG;
> + }
> +
> + len += sysfs_emit_at(buf, len, "\n");
> +
> + return len;
> +}
> +
> static ssize_t iio_read_channel_info_avail(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> @@ -860,6 +883,8 @@ static ssize_t iio_read_channel_info_avail(struct device *dev,
> return iio_format_avail_list(buf, vals, type, length);
> case IIO_AVAIL_RANGE:
> return iio_format_avail_range(buf, vals, type);
> + case IIO_AVAIL_LIST_WITH_TYPE:
> + return iio_format_avail_list_with_type(buf, vals, length);
> default:
> return -EINVAL;
> }
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index e8a25852f0df..92d225f1ddd5 100644
> --- a/drivers/iio/inkern.c
> +++ b/drivers/iio/inkern.c
> @@ -855,6 +855,29 @@ static int iio_channel_read_max(struct iio_channel *chan,
> }
> return 0;
>
> + case IIO_AVAIL_LIST_WITH_TYPE:
> + if (length <= 0 || length % 3 != 0)
> + return -EINVAL;
> +
> + if (vals[length - 1] != IIO_VAL_INT) {
> + /* FIXME: learn about max for other iio values */
> + return -EINVAL;
> + }
> +
> + *val = vals[length - 3];
> + length -= 3;
> +
> + for (; length; length -= 3) {
> + if (vals[length - 1] != IIO_VAL_INT) {
> + /* FIXME: learn about max for other iio values */
> + return -EINVAL;
> + }
> +
> + if (vals[length - 3] > *val)
> + *val = vals[length - 3];
> + }
> + return 0;
> +
> default:
> return ret;
> }
> diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
> index 5fa5957586cf..99dd12e10fb6 100644
> --- a/include/linux/iio/consumer.h
> +++ b/include/linux/iio/consumer.h
> @@ -309,7 +309,8 @@ int iio_read_max_channel_raw(struct iio_channel *chan, int *val);
> * @vals: Available values read back.
> * @length: Number of entries in vals.
> *
> - * Returns an error code, IIO_AVAIL_RANGE or IIO_AVAIL_LIST.
> + * Returns an error code, IIO_AVAIL_RANGE, IIO_AVAIL_LIST or
> + * IIO_AVAIL_LIST_WITH_TYPE.
> *
> * For ranges, three vals are always returned; min, step and max.
> * For lists, all the possible values are enumerated.
> @@ -328,7 +329,8 @@ int iio_read_avail_channel_raw(struct iio_channel *chan,
> * @length: Number of entries in vals.
> * @attribute: info attribute to be read back.
> *
> - * Returns an error code, IIO_AVAIL_RANGE or IIO_AVAIL_LIST.
> + * Returns an error code, IIO_AVAIL_RANGE, IIO_AVAIL_LIST or
> + * IIO_AVAIL_LIST_WITH_TYPE.
> */
> int iio_read_avail_channel_attribute(struct iio_channel *chan,
> const int **vals, int *type, int *length,
> diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h
> index a7aa91f3a8dc..9777d1357080 100644
> --- a/include/linux/iio/types.h
> +++ b/include/linux/iio/types.h
> @@ -32,6 +32,7 @@ enum iio_event_info {
> enum iio_available_type {
> IIO_AVAIL_LIST,
> IIO_AVAIL_RANGE,
> + IIO_AVAIL_LIST_WITH_TYPE,
> };
>
> enum iio_chan_info_enum {
