linux-kernel - [PATCH 3/3] iio: mpl3115: add support for sampling frequency

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Message-Id: <20250921133327.123726-4-apokusinski01@gmail.com>
Date: Sun, 21 Sep 2025 15:33:28 +0200
From: Antoni Pokusinski <apokusinski01@...il.com>
To: jic23@...nel.org,
	dlechner@...libre.com,
	nuno.sa@...log.com,
	andy@...nel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org
Cc: linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-iio@...r.kernel.org,
	linux@...ck-us.net,
	rodrigo.gobbi.7@...il.com,
	naresh.solanki@...ements.com,
	michal.simek@....com,
	grantpeltier93@...il.com,
	farouk.bouabid@...rry.de,
	marcelo.schmitt1@...il.com,
	Antoni Pokusinski <apokusinski01@...il.com>
Subject: [PATCH 3/3] iio: mpl3115: add support for sampling frequency

When the device is in ACTIVE mode the temperature and pressure measurements
are collected with a frequency determined by the ST[3:0] bits of CTRL_REG2
register.

Signed-off-by: Antoni Pokusinski <apokusinski01@...il.com>
---
 drivers/iio/pressure/mpl3115.c | 80 ++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/drivers/iio/pressure/mpl3115.c b/drivers/iio/pressure/mpl3115.c
index cf34de8f0d7e..2f1860ca1f32 100644
--- a/drivers/iio/pressure/mpl3115.c
+++ b/drivers/iio/pressure/mpl3115.c
@@ -28,6 +28,7 @@
 #define MPL3115_INT_SOURCE 0x12
 #define MPL3115_PT_DATA_CFG 0x13
 #define MPL3115_CTRL_REG1 0x26
+#define MPL3115_CTRL_REG2 0x27
 #define MPL3115_CTRL_REG3 0x28
 #define MPL3115_CTRL_REG4 0x29
 #define MPL3115_CTRL_REG5 0x2a
@@ -46,6 +47,8 @@
 #define MPL3115_CTRL_ACTIVE BIT(0) /* continuous measurement */
 #define MPL3115_CTRL_OS_258MS (BIT(5) | BIT(4)) /* 64x oversampling */
 
+#define MPL3115_CTRL_ST (BIT(3) | BIT(2) | BIT(1) | BIT(0))
+
 #define MPL3115_CTRL_IPOL1 BIT(5)
 #define MPL3115_CTRL_IPOL2 BIT(1)
 
@@ -53,6 +56,25 @@
 
 #define MPL3115_CTRL_INT_CFG_DRDY BIT(7)
 
+static const unsigned int mpl3115_samp_freq_table[][2] = {
+	{ 1,      0},
+	{ 0, 500000},
+	{ 0, 250000},
+	{ 0, 125000},
+	{ 0,  62500},
+	{ 0,  31250},
+	{ 0,  15625},
+	{ 0,   7812},
+	{ 0,   3906},
+	{ 0,   1953},
+	{ 0,    976},
+	{ 0,    488},
+	{ 0,    244},
+	{ 0,    122},
+	{ 0,     61},
+	{ 0,     30},
+};
+
 struct mpl3115_data {
 	struct i2c_client *client;
 	struct iio_trigger *drdy_trig;
@@ -163,10 +185,60 @@ static int mpl3115_read_raw(struct iio_dev *indio_dev,
 		default:
 			return -EINVAL;
 		}
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = i2c_smbus_read_byte_data(data->client, MPL3115_CTRL_REG2);
+		if (ret < 0)
+			return ret;
+
+		ret &= MPL3115_CTRL_ST;
+
+		*val = mpl3115_samp_freq_table[ret][0];
+		*val2 = mpl3115_samp_freq_table[ret][1];
+		return IIO_VAL_INT_PLUS_MICRO;
 	}
 	return -EINVAL;
 }
 
+static int mpl3115_read_avail(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      const int **vals, int *type, int *length,
+			      long mask)
+{
+	if (mask != IIO_CHAN_INFO_SAMP_FREQ)
+		return -EINVAL;
+
+	*type = IIO_VAL_INT_PLUS_MICRO;
+	*length = ARRAY_SIZE(mpl3115_samp_freq_table) * 2;
+	*vals = (int *)mpl3115_samp_freq_table;
+	return IIO_AVAIL_LIST;
+}
+
+static int mpl3115_write_raw(struct iio_dev *indio_dev,
+			     const struct iio_chan_spec *chan,
+			     int val, int val2, long mask)
+{
+	struct mpl3115_data *data = iio_priv(indio_dev);
+	int i, ret;
+
+	if (mask != IIO_CHAN_INFO_SAMP_FREQ)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(mpl3115_samp_freq_table); i++)
+		if (val == mpl3115_samp_freq_table[i][0] &&
+		    val2 == mpl3115_samp_freq_table[i][1])
+			break;
+
+	if (i == ARRAY_SIZE(mpl3115_samp_freq_table))
+		return -EINVAL;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = i2c_smbus_write_byte_data(data->client, MPL3115_CTRL_REG2, i);
+	iio_device_release_direct(indio_dev);
+	return ret;
+}
+
 static irqreturn_t mpl3115_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
@@ -224,6 +296,9 @@ static const struct iio_chan_spec mpl3115_channels[] = {
 		.type = IIO_PRESSURE,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all_available =
+			BIT(IIO_CHAN_INFO_SAMP_FREQ),
 		.scan_index = 0,
 		.scan_type = {
 			.sign = 'u',
@@ -237,6 +312,9 @@ static const struct iio_chan_spec mpl3115_channels[] = {
 		.type = IIO_TEMP,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all_available =
+			BIT(IIO_CHAN_INFO_SAMP_FREQ),
 		.scan_index = 1,
 		.scan_type = {
 			.sign = 's',
@@ -307,6 +385,8 @@ static const struct iio_trigger_ops mpl3115_trigger_ops = {
 
 static const struct iio_info mpl3115_info = {
 	.read_raw = &mpl3115_read_raw,
+	.read_avail = &mpl3115_read_avail,
+	.write_raw = &mpl3115_write_raw,
 };
 
 static int mpl3115_trigger_probe(struct mpl3115_data *data,
-- 
2.25.1