linux-kernel - [PATCH v6 2/2] iio: Handle enumerated properties with gaps

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Message-ID: <20201222131312.64957-2-alexandru.ardelean@analog.com>
Date:   Tue, 22 Dec 2020 15:13:12 +0200
From:   Alexandru Ardelean <alexandru.ardelean@...log.com>
To:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <jic23@...nel.org>, <lars@...afoo.de>, <akpm@...ux-foundation.org>,
        <gregkh@...uxfoundation.org>, <andy.shevchenko@...il.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>
Subject: [PATCH v6 2/2] iio: Handle enumerated properties with gaps

From: Lars-Peter Clausen <lars@...afoo.de>

Some enums might have gaps or reserved values in the middle of their value
range. E.g. consider a 2-bit enum where the values 0, 1 and 3 have a
meaning, but 2 is a reserved value and can not be used.

Add support for such enums to the IIO enum helper functions. A reserved
values is marked by setting its entry in the items array to NULL rather
than the normal descriptive string value.

Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
---
 drivers/iio/industrialio-core.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index e9ee9363fed0..5f6211bfb428 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -470,8 +470,11 @@ ssize_t iio_enum_available_read(struct iio_dev *indio_dev,
 	if (!e->num_items)
 		return 0;
 
-	for (i = 0; i < e->num_items; ++i)
+	for (i = 0; i < e->num_items; ++i) {
+		if (!e->items[i])
+			continue;
 		len += scnprintf(buf + len, PAGE_SIZE - len, "%s ", e->items[i]);
+	}
 
 	/* replace last space with a newline */
 	buf[len - 1] = '\n';
@@ -492,7 +495,7 @@ ssize_t iio_enum_read(struct iio_dev *indio_dev,
 	i = e->get(indio_dev, chan);
 	if (i < 0)
 		return i;
-	else if (i >= e->num_items)
+	else if (i >= e->num_items || !e->items[i])
 		return -EINVAL;
 
 	return snprintf(buf, PAGE_SIZE, "%s\n", e->items[i]);
@@ -509,7 +512,7 @@ ssize_t iio_enum_write(struct iio_dev *indio_dev,
 	if (!e->set)
 		return -EINVAL;
 
-	ret = __sysfs_match_string(e->items, e->num_items, buf);
+	ret = __sysfs_match_string_with_gaps(e->items, e->num_items, buf);
 	if (ret < 0)
 		return ret;
 
-- 
2.17.1