linux-kernel - [PATCH 05/10] iio: accel: BMA220 make use of the watchdog functionality

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Message-ID: <20250901194742.11599-6-petre.rodan@subdimension.ro>
Date: Mon,  1 Sep 2025 22:47:31 +0300
From: Petre Rodan <petre.rodan@...dimension.ro>
To: linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Petre Rodan <petre.rodan@...dimension.ro>,
	Jonathan Cameron <jic23@...nel.org>,
	David Lechner <dlechner@...libre.com>,
	Nuno Sá <nuno.sa@...log.com>,
	Andy Shevchenko <andy@...nel.org>
Subject: [PATCH 05/10] iio: accel: BMA220 make use of the watchdog functionality

Sometimes the sensor gets stuck and enters a condition in which it pulls
SDA low, thus making the entire i2c bus unusable.
The optional bosch,watchdog property mitigates this problem by clearing
the condition after a period of 1 or 10ms.

Signed-off-by: Petre Rodan <petre.rodan@...dimension.ro>
---
 drivers/iio/accel/bma220_core.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/iio/accel/bma220_core.c b/drivers/iio/accel/bma220_core.c
index fae84823d52b..86347cf8ab1e 100644
--- a/drivers/iio/accel/bma220_core.c
+++ b/drivers/iio/accel/bma220_core.c
@@ -158,6 +158,12 @@ enum bma220_axis {
 	AXIS_Z,
 };

+enum bma220_prop_wdt {
+	BMA220_PROP_WDT_OFF,
+	BMA220_PROP_WDT_1MS,
+	BMA220_PROP_WDT_10MS,
+};
+
 static const int bma220_scale_table[][2] = {
 	{0, 623000}, {1, 248000}, {2, 491000}, {4, 983000},
 };
@@ -428,10 +434,17 @@ static int bma220_power(struct bma220_data *data, bool up)
 	return -EBUSY;
 }

+static int bma220_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;
 	unsigned int val;
+	u32 watchdog;
 	static const char * const regulator_names[] = { "vddd", "vddio", "vdda" };

 	ret = devm_regulator_bulk_get_enable(data->dev,
@@ -462,6 +475,25 @@ static int bma220_init(struct bma220_data *data)
 		return ret;
 	}

+	ret = device_property_read_u32(data->dev, "bosch,watchdog", &watchdog);
+	if (!ret) {
+		switch (watchdog) {
+		case BMA220_PROP_WDT_1MS:
+			ret = bma220_wdt(data, BMA220_WDT_1MS);
+			break;
+		case BMA220_PROP_WDT_10MS:
+			ret = bma220_wdt(data, BMA220_WDT_10MS);
+			break;
+		default:
+			ret = bma220_wdt(data, BMA220_WDT_OFF);
+			break;
+		}
+		if (ret) {
+			dev_err(data->dev, "Failed to set watchdog\n");
+			return ret;
+		}
+	}
+
 	return 0;
 }

--
2.49.1