linux-kernel - [PATCH v3 14/18] iio: accel: bma220: add i2c watchdog feature

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Message-Id: <20250913-b4-bma220_improvements-v3-14-0b97279b4e45@subdimension.ro>
Date: Sat, 13 Sep 2025 18:39:35 +0300
From: Petre Rodan <petre.rodan@...dimension.ro>
To: Jonathan Cameron <jic23@...nel.org>, 
 David Lechner <dlechner@...libre.com>, 
 Nuno Sá <nuno.sa@...log.com>, 
 Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>, 
 linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Petre Rodan <petre.rodan@...dimension.ro>
Subject: [PATCH v3 14/18] iio: accel: bma220: add i2c watchdog feature

Sometimes the sensor gets stuck and enters a condition in which it pulls
SDA low, thus making the entire i2c bus unusable.
This problem is mitigated by activating a 1ms watchdog implemented in
the sensor.

Signed-off-by: Petre Rodan <petre.rodan@...dimension.ro>
---
v1->v2
- hardcode 1ms timer watchdog to any i2c-based sensor instead of
  configuring a dt-based property
- rename bma220_wdt() to bma220_set_wdt()
v2->v3 no change
---
 drivers/iio/accel/bma220_core.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/iio/accel/bma220_core.c b/drivers/iio/accel/bma220_core.c
index 5eef47151501119ab792aab6a511938a16c1ade1..425a8b981e141aa496351f29df0597c989aa4a0a 100644
--- a/drivers/iio/accel/bma220_core.c
+++ b/drivers/iio/accel/bma220_core.c
@@ -10,6 +10,7 @@
 #include <linux/bitfield.h>
 #include <linux/cleanup.h>
 #include <linux/device.h>
+#include <linux/i2c.h>
 #include <linux/kernel.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
@@ -358,6 +359,12 @@ static int bma220_power(struct bma220_data *data, bool up)
 	return -EBUSY;
 }
 
+static int bma220_set_wdt(struct bma220_data *data, const u8 val)
+{
+	return regmap_update_bits(data->regmap, BMA220_REG_WDT, BMA220_WDT_MASK,
+				  FIELD_PREP(BMA220_WDT_MASK, val));
+}
+
 static int bma220_init(struct bma220_data *data)
 {
 	int ret;
@@ -388,6 +395,13 @@ static int bma220_init(struct bma220_data *data)
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to soft reset chip\n");
 
+	if (i2c_verify_client(dev)) {
+		ret = bma220_set_wdt(data, BMA220_WDT_1MS);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to set i2c watchdog\n");
+	}
+
 	return 0;
 }
 

-- 
2.49.1