[PATCH] iio: imu: inv_icm42600: add buffer hwfifo watermark attributes

[PATCH] iio: imu: inv_icm42600: add buffer hwfifo watermark attributes

[Jean-Baptiste Maneyrol via B4 Relay]

From: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>

Add hwfifo_watermark/min/max/enabled buffer attributes.
Hardware FIFO is always enabled and used.

Signed-off-by: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>
---
 drivers/iio/imu/inv_icm42600/inv_icm42600.h        |  2 ++
 drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c  |  5 +--
 drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.c | 37 ++++++++++++++++++++++
 drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.h |  1 +
 drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c   |  5 +--
 5 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600.h b/drivers/iio/imu/inv_icm42600/inv_icm42600.h
index c8b48a5c5ed0..7c9b63584a05 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600.h
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600.h
@@ -354,6 +354,8 @@ struct inv_icm42600_sensor_state {
 		cpu_to_le16((_wm) & GENMASK(11, 0))
 /* FIFO is 2048 bytes, let 12 samples for reading latency */
 #define INV_ICM42600_FIFO_WATERMARK_MAX			(2048 - 12 * 16)
+/* INV_ICM42600_FIFO_WATERMARK_MAX / 8 = 232 */
+#define INV_ICM42600_FIFO_WATERMARK_MAX_SAMPLES		232
 
 #define INV_ICM42600_REG_INT_CONFIG1			0x0064
 #define INV_ICM42600_INT_CONFIG1_TPULSE_DURATION	BIT(6)
diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
index 532d5fdffaf8..1ab73953bef6 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
@@ -1186,8 +1186,9 @@ struct iio_dev *inv_icm42600_accel_init(struct inv_icm42600_state *st)
 	indio_dev->num_channels = ARRAY_SIZE(inv_icm42600_accel_channels);
 	indio_dev->available_scan_masks = inv_icm42600_accel_scan_masks;
 
-	ret = devm_iio_kfifo_buffer_setup(dev, indio_dev,
-					  &inv_icm42600_buffer_ops);
+	ret = devm_iio_kfifo_buffer_setup_ext(dev, indio_dev,
+					      &inv_icm42600_buffer_ops,
+					      inv_icm42600_buffer_attrs);
 	if (ret)
 		return ERR_PTR(ret);
 
diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.c
index 68a395758031..0399cce94545 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.c
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.c
@@ -10,10 +10,12 @@
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/delay.h>
+#include <linux/stringify.h>
 
 #include <linux/iio/buffer.h>
 #include <linux/iio/common/inv_sensors_timestamp.h>
 #include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
 
 #include "inv_icm42600.h"
 #include "inv_icm42600_buffer.h"
@@ -437,6 +439,41 @@ const struct iio_buffer_setup_ops inv_icm42600_buffer_ops = {
 	.postdisable = inv_icm42600_buffer_postdisable,
 };
 
+static ssize_t inv_icm42600_buffer_get_watermark(struct device *dev,
+						 struct device_attribute *attr,
+						 char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
+	unsigned int wm;
+
+	guard(mutex)(&st->lock);
+
+	if (indio_dev == st->indio_accel)
+		wm = st->fifo.watermark.eff_accel;
+	else if (indio_dev == st->indio_gyro)
+		wm = st->fifo.watermark.eff_gyro;
+	else
+		return -EINVAL;
+
+	return sysfs_emit(buf, "%u\n", wm);
+}
+
+IIO_STATIC_CONST_DEVICE_ATTR(hwfifo_watermark_min, "1");
+IIO_STATIC_CONST_DEVICE_ATTR(hwfifo_watermark_max,
+			     __stringify(INV_ICM42600_FIFO_WATERMARK_MAX_SAMPLES));
+static IIO_DEVICE_ATTR(hwfifo_watermark, 0444, inv_icm42600_buffer_get_watermark,
+		       NULL, 0);
+IIO_STATIC_CONST_DEVICE_ATTR(hwfifo_enabled, "1");
+
+const struct iio_dev_attr *inv_icm42600_buffer_attrs[] = {
+	&iio_dev_attr_hwfifo_watermark_min,
+	&iio_dev_attr_hwfifo_watermark_max,
+	&iio_dev_attr_hwfifo_watermark,
+	&iio_dev_attr_hwfifo_enabled,
+	NULL,
+};
+
 int inv_icm42600_buffer_fifo_read(struct inv_icm42600_state *st,
 				  unsigned int max)
 {
diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.h b/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.h
index ffca4da1e249..522e158accc9 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.h
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.h
@@ -79,6 +79,7 @@ ssize_t inv_icm42600_fifo_decode_packet(const void *packet, const void **accel,
 					const void **timestamp, unsigned int *odr);
 
 extern const struct iio_buffer_setup_ops inv_icm42600_buffer_ops;
+extern const struct iio_dev_attr *inv_icm42600_buffer_attrs[];
 
 int inv_icm42600_buffer_init(struct inv_icm42600_state *st);
 
diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c
index 11339ddf1da3..7d4f6701f124 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c
@@ -772,8 +772,9 @@ struct iio_dev *inv_icm42600_gyro_init(struct inv_icm42600_state *st)
 	indio_dev->available_scan_masks = inv_icm42600_gyro_scan_masks;
 	indio_dev->setup_ops = &inv_icm42600_buffer_ops;
 
-	ret = devm_iio_kfifo_buffer_setup(dev, indio_dev,
-					  &inv_icm42600_buffer_ops);
+	ret = devm_iio_kfifo_buffer_setup_ext(dev, indio_dev,
+					      &inv_icm42600_buffer_ops,
+					      inv_icm42600_buffer_attrs);
 	if (ret)
 		return ERR_PTR(ret);
 

---
base-commit: cc746297b23e89bd5df9f91f3a0ca209e8991763
change-id: 20260622-inv-icm42600-add-buffer-hwfifo_attributes-aced0415e341

Best regards,
--  
Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>

Re: [PATCH] iio: imu: inv_icm42600: add buffer hwfifo watermark attributes

[Andy Shevchenko]

On Tue, Jun 23, 2026 at 12:10:38PM +0200, Jean-Baptiste Maneyrol via B4 Relay wrote:

> Add hwfifo_watermark/min/max/enabled buffer attributes.
> Hardware FIFO is always enabled and used.

...

> +const struct iio_dev_attr *inv_icm42600_buffer_attrs[] = {
> +	&iio_dev_attr_hwfifo_watermark_min,
> +	&iio_dev_attr_hwfifo_watermark_max,
> +	&iio_dev_attr_hwfifo_watermark,
> +	&iio_dev_attr_hwfifo_enabled,
> +	NULL,

No trailing comma in terminator entries.

> +};

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] iio: imu: inv_icm42600: add buffer hwfifo watermark attributes

[Jean-Baptiste Maneyrol]

>From: Andy Shevchenko <andriy.shevchenko@intel.com>
>Sent: Tuesday, June 23, 2026 22:18
>To: Jean-Baptiste Maneyrol
>Cc: Jonathan Cameron; David Lechner; Nuno Sá; Andy Shevchenko; linux-iio@vger.kernel.org; linux-kernel@vger.kernel.org
>Subject: Re: [PATCH] iio: imu: inv_icm42600: add buffer hwfifo watermark attributes
>
>On Tue, Jun 23, 2026 at 12: 10: 38PM +0200, Jean-Baptiste Maneyrol via B4 Relay wrote: > Add hwfifo_watermark/min/max/enabled buffer attributes. > Hardware FIFO is always enabled and used. .. . > +const struct iio_dev_attr *inv_icm42600_buffer_attrs[]
>ZjQcmQRYFpfptBannerStart
>This Message Is From an External Sender
>This message came from outside your organization.
>
>ZjQcmQRYFpfptBannerEnd
>
>On Tue, Jun 23, 2026 at 12:10:38PM +0200, Jean-Baptiste Maneyrol via B4 Relay wrote:
>
>> Add hwfifo_watermark/min/max/enabled buffer attributes.
>> Hardware FIFO is always enabled and used.
>
>...
>
>> +const struct iio_dev_attr *inv_icm42600_buffer_attrs[] = {
>> +     &iio_dev_attr_hwfifo_watermark_min,
>> +     &iio_dev_attr_hwfifo_watermark_max,
>> +     &iio_dev_attr_hwfifo_watermark,
>> +     &iio_dev_attr_hwfifo_enabled,
>> +     NULL,
>
>No trailing comma in terminator entries.
>

Hello Andy,

no problem, will do a V2 with the fix.

Thanks,
JB

>> +};
>
>--
>With Best Regards,
>Andy Shevchenko
>