linux-kernel - [PATCH v4 2/2] staging: iio: frequency: ad9832: Refactor powerdown control

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Message-ID: <20250424223210.91317-3-gshahrouzi@gmail.com>
Date: Thu, 24 Apr 2025 18:32:09 -0400
From: Gabriel Shahrouzi <gshahrouzi@...il.com>
To: andy@...nel.org,
	dlechner@...libre.com,
	gregkh@...uxfoundation.org,
	jic23@...nel.org,
	lars@...afoo.de,
	linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-staging@...ts.linux.dev,
	Michael.Hennerich@...log.com,
	nuno.sa@...log.com
Cc: gshahrouzi@...il.com,
	skhan@...uxfoundation.org,
	linux-kernel-mentees@...ts.linux.dev
Subject: [PATCH v4 2/2] staging: iio: frequency: ad9832: Refactor powerdown control

Replace custom implementation with out_altvoltage_powerdown ABI. The
attribute's logic is inverted (1 now enables powerdown) to match the
standard.

Signed-off-by: Gabriel Shahrouzi <gshahrouzi@...il.com>
---
V3 -> v4:
	- Use guard(mutex) for simplified locking.
	- Use an extended attribute.
v2 -> v3:
v1 -> v2:
	Refactor powerdown functionality.
---
 drivers/staging/iio/frequency/ad9832.c | 69 +++++++++++++++++++-------
 1 file changed, 51 insertions(+), 18 deletions(-)

diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/frequency/ad9832.c
index 2e555084ff98a..b8b52302abf36 100644
--- a/drivers/staging/iio/frequency/ad9832.c
+++ b/drivers/staging/iio/frequency/ad9832.c
@@ -174,6 +174,32 @@ static int ad9832_write_phase(struct ad9832_state *st,
 	return spi_sync(st->spi, &st->phase_msg);
 }
 
+static ssize_t ad9832_write_powerdown(struct iio_dev *indio_dev, uintptr_t private,
+				      const struct iio_chan_spec *chan,
+				      const char *buf, size_t len)
+{
+	struct ad9832_state *st = iio_priv(indio_dev);
+	int ret;
+	bool val;
+
+	ret = kstrtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&st->lock);
+	if (val)
+		st->ctrl_src |= AD9832_SLEEP;
+	else
+		st->ctrl_src &= ~(AD9832_RESET | AD9832_SLEEP |
+				 AD9832_CLR);
+
+	st->data = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, AD9832_CMD_SLEEPRESCLR) |
+					  st->ctrl_src);
+	ret = spi_sync(st->spi, &st->msg);
+
+	return ret ? ret : len;
+}
+
 static ssize_t ad9832_write(struct device *dev, struct device_attribute *attr,
 			    const char *buf, size_t len)
 {
@@ -185,9 +211,9 @@ static ssize_t ad9832_write(struct device *dev, struct device_attribute *attr,
 
 	ret = kstrtoul(buf, 10, &val);
 	if (ret)
-		goto error_ret;
+		return ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 	switch ((u32)this_attr->address) {
 	case AD9832_FREQ0HM:
 	case AD9832_FREQ1HM:
@@ -232,22 +258,9 @@ static ssize_t ad9832_write(struct device *dev, struct device_attribute *attr,
 						  st->ctrl_fp);
 		ret = spi_sync(st->spi, &st->msg);
 		break;
-	case AD9832_OUTPUT_EN:
-		if (val)
-			st->ctrl_src &= ~(AD9832_RESET | AD9832_SLEEP | AD9832_CLR);
-		else
-			st->ctrl_src |= FIELD_PREP(AD9832_SLEEP, 1);
-
-		st->data = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, AD9832_CMD_SLEEPRESCLR) |
-						  st->ctrl_src);
-		ret = spi_sync(st->spi, &st->msg);
-		break;
 	default:
 		ret = -ENODEV;
 	}
-	mutex_unlock(&st->lock);
-
-error_ret:
 	return ret ? ret : len;
 }
 
@@ -270,8 +283,6 @@ static IIO_CONST_ATTR_PHASE_SCALE(0, "0.0015339808"); /* 2PI/2^12 rad*/
 
 static IIO_DEV_ATTR_PINCONTROL_EN(0, 0200, NULL,
 				ad9832_write, AD9832_PINCTRL_EN);
-static IIO_DEV_ATTR_OUT_ENABLE(0, 0200, NULL,
-				ad9832_write, AD9832_OUTPUT_EN);
 
 static struct attribute *ad9832_attributes[] = {
 	&iio_dev_attr_out_altvoltage0_frequency0.dev_attr.attr,
@@ -285,7 +296,6 @@ static struct attribute *ad9832_attributes[] = {
 	&iio_dev_attr_out_altvoltage0_pincontrol_en.dev_attr.attr,
 	&iio_dev_attr_out_altvoltage0_frequencysymbol.dev_attr.attr,
 	&iio_dev_attr_out_altvoltage0_phasesymbol.dev_attr.attr,
-	&iio_dev_attr_out_altvoltage0_out_enable.dev_attr.attr,
 	NULL,
 };
 
@@ -293,6 +303,27 @@ static const struct attribute_group ad9832_attribute_group = {
 	.attrs = ad9832_attributes,
 };
 
+static const struct iio_chan_spec_ext_info ad9832_ext_info[] = {
+	{
+		.name = "powerdown",
+		.shared = IIO_SEPARATE,
+		.write = ad9832_write_powerdown,
+	},
+	{ },
+};
+
+#define AD9832_CHANNEL(chan) {					\
+	.type = IIO_ALTVOLTAGE,					\
+	.indexed = 1,						\
+	.output = 1,						\
+	.channel = (chan),					\
+	.ext_info = ad9832_ext_info,				\
+}
+
+static const struct iio_chan_spec ad9832_channels[] = {
+	AD9832_CHANNEL(0),
+};
+
 static const struct iio_info ad9832_info = {
 	.attrs = &ad9832_attribute_group,
 };
@@ -333,6 +364,8 @@ static int ad9832_probe(struct spi_device *spi)
 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->info = &ad9832_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ad9832_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ad9832_channels);
 
 	/* Setup default messages */
 
-- 
2.43.0