[PATCH v2 07/14] iio: accel: bma220: reset registers during init stage

Petre Rodan
2025-09-10T07:58:12Z

Bring all configuration registers to default values during device probe().

Signed-off-by: Petre Rodan <petre.rodan@subdimension.ro>
---
drivers/iio/accel/bma220_core.c | 71 ++++++++++++++++++++++++++++-------------
1 file changed, 49 insertions(+), 22 deletions(-)

diff --git a/drivers/iio/accel/bma220_core.c b/drivers/iio/accel/bma220_core.c
index b6f1374a9cca52966c1055113710061a7284cf5a..322df516c90a7c645eeca579cae9803eb31caad1 100644
--- a/drivers/iio/accel/bma220_core.c
+++ b/drivers/iio/accel/bma220_core.c
@@ -29,12 +29,15 @@
#define BMA220_REG_ACCEL_Z 0x04
#define BMA220_REG_RANGE 0x11
#define BMA220_REG_SUSPEND 0x18
+#define BMA220_REG_SOFTRESET 0x19

#define BMA220_CHIP_ID 0xDD
#define BMA220_READ_MASK BIT(7)
#define BMA220_RANGE_MASK GENMASK(1, 0)
#define BMA220_SUSPEND_SLEEP 0xFF
#define BMA220_SUSPEND_WAKE 0x00
+#define BMA220_RESET_MODE 0xFF
+#define BMA220_NONRESET_MODE 0x00

#define BMA220_DEVICE_NAME "bma220"

@@ -203,31 +206,28 @@ static const struct iio_info bma220_info = {
.read_avail = bma220_read_avail,
};

-static int bma220_init(struct spi_device *spi)
+static int bma220_reset(struct spi_device *spi, bool up)
{
- int ret;
- static const char * const regulator_names[] = { "vddd", "vddio", "vdda" };
+ int i, ret;

- ret = devm_regulator_bulk_get_enable(&spi->dev,
- ARRAY_SIZE(regulator_names),
- regulator_names);
- if (ret)
- return dev_err_probe(&spi->dev, ret, "Failed to get regulators\n");
+ /**
+ * The chip can be reset by a simple register read.
+ * We need up to 2 register reads of the softreset register
+ * to make sure that the device is in the desired state.
+ */
+ for (i = 0; i < 2; i++) {
+ ret = bma220_read_reg(spi, BMA220_REG_SOFTRESET);
+ if (ret < 0)
+ return ret;

- ret = bma220_read_reg(spi, BMA220_REG_ID);
- if (ret != BMA220_CHIP_ID)
- return -ENODEV;
+ if (up && (ret == BMA220_RESET_MODE))
+ return 0;

- /* Make sure the chip is powered on */
- ret = bma220_read_reg(spi, BMA220_REG_SUSPEND);
- if (ret == BMA220_SUSPEND_WAKE)
- ret = bma220_read_reg(spi, BMA220_REG_SUSPEND);
- if (ret < 0)
- return ret;
- if (ret == BMA220_SUSPEND_WAKE)
- return -EBUSY;
+ if (!up && (ret == BMA220_NONRESET_MODE))
+ return 0;
+ }

- return 0;
+ return -EBUSY;
}

static int bma220_power(struct spi_device *spi, bool up)
@@ -244,16 +244,43 @@ static int bma220_power(struct spi_device *spi, bool up)
if (ret < 0)
return ret;

- if (up && ret == BMA220_SUSPEND_SLEEP)
+ if (up && (ret == BMA220_SUSPEND_SLEEP))
return 0;

- if (!up && ret == BMA220_SUSPEND_WAKE)
+ if (!up && (ret == BMA220_SUSPEND_WAKE))
return 0;
}

return -EBUSY;
}

+static int bma220_init(struct spi_device *spi)
+{
+ int ret;
+ static const char * const regulator_names[] = { "vddd", "vddio", "vdda" };
+
+ ret = devm_regulator_bulk_get_enable(&spi->dev,
+ ARRAY_SIZE(regulator_names),
+ regulator_names);
+ if (ret)
+ return dev_err_probe(&spi->dev, ret, "Failed to get regulators\n");
+
+ ret = bma220_read_reg(spi, BMA220_REG_ID);
+ if (ret != BMA220_CHIP_ID)
+ return -ENODEV;
+
+ /* Make sure the chip is powered on and config registers are reset */
+ ret = bma220_power(spi, true);
+ if (ret)
+ return dev_err_probe(&spi->dev, ret, "Failed to power-on chip\n");
+
+ ret = bma220_reset(spi, true);
+ if (ret)
+ return dev_err_probe(&spi->dev, ret, "Failed to soft reset chip\n");
+
+ return 0;
+}
+
static void bma220_deinit(void *spi)
{
bma220_power(spi, false);

--
2.49.1