linux-kernel - [PATCH v3 06/10] iio: pressure: mprls0025pa remove defaults

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Date: Fri, 29 Dec 2023 11:24:34 +0200
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>,
	Andreas Klinger <ak@...klinger.de>,
	Jonathan Cameron <jic23@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Angel Iglesias <ang.iglesiasg@...il.com>,
	Matti Vaittinen <mazziesaccount@...il.com>
Subject: [PATCH v3 06/10] iio: pressure: mprls0025pa remove defaults

This driver supports 32*3 combinations of fixed ranges and transfer
functions, plus custom ranges.

So statistically a user has more than 99% chance that the provided
default configuration will generate invalid pressure readings if the
bindings are not initialized and the driver is instantiated via sysfs.

The current patch removes this loophole making sure the driver loads
only if the firmware properties are present.

Co-developed-by: Andreas Klinger <ak@...klinger.de>
Signed-off-by: Andreas Klinger <ak@...klinger.de>
Signed-off-by: Petre Rodan <petre.rodan@...dimension.ro>
---
v2 -> v3 drop the use of dev_fwnode() entirely

 drivers/iio/pressure/mprls0025pa.c | 48 +++++++++++++-----------------
 1 file changed, 20 insertions(+), 28 deletions(-)

diff --git a/drivers/iio/pressure/mprls0025pa.c b/drivers/iio/pressure/mprls0025pa.c
index 233cc1dc38ad..e0a2a60c6245 100644
--- a/drivers/iio/pressure/mprls0025pa.c
+++ b/drivers/iio/pressure/mprls0025pa.c
@@ -353,34 +353,26 @@ static int mpr_probe(struct i2c_client *client)
 		return dev_err_probe(dev, ret,
 				"can't get and enable vdd supply\n");

-	if (dev_fwnode(dev)) {
-		ret = device_property_read_u32(dev, "honeywell,pmin-pascal",
-								&data->pmin);
-		if (ret)
-			return dev_err_probe(dev, ret,
-				"honeywell,pmin-pascal could not be read\n");
-		ret = device_property_read_u32(dev, "honeywell,pmax-pascal",
-								&data->pmax);
-		if (ret)
-			return dev_err_probe(dev, ret,
-				"honeywell,pmax-pascal could not be read\n");
-		ret = device_property_read_u32(dev,
-				"honeywell,transfer-function", &func);
-		if (ret)
-			return dev_err_probe(dev, ret,
-				"honeywell,transfer-function could not be read\n");
-		data->function = func - 1;
-		if (data->function > MPR_FUNCTION_C)
-			return dev_err_probe(dev, -EINVAL,
-				"honeywell,transfer-function %d invalid\n",
-								data->function);
-	} else {
-		/* when loaded as i2c device we need to use default values */
-		dev_notice(dev, "firmware node not found; using defaults\n");
-		data->pmin = 0;
-		data->pmax = 172369; /* 25 psi */
-		data->function = MPR_FUNCTION_A;
-	}
+	ret = device_property_read_u32(dev, "honeywell,pmin-pascal",
+				       &data->pmin);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				   "honeywell,pmin-pascal could not be read\n");
+	ret = device_property_read_u32(dev, "honeywell,pmax-pascal",
+				       &data->pmax);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				   "honeywell,pmax-pascal could not be read\n");
+	ret = device_property_read_u32(dev,
+				       "honeywell,transfer-function", &func);
+	if (ret)
+		return dev_err_probe(dev, ret,
+			     "honeywell,transfer-function could not be read\n");
+	data->function = func - 1;
+	if (data->function > MPR_FUNCTION_C)
+		return dev_err_probe(dev, -EINVAL,
+				     "honeywell,transfer-function %d invalid\n",
+				     data->function);

 	data->outmin = mpr_func_spec[data->function].output_min;
 	data->outmax = mpr_func_spec[data->function].output_max;
--
2.41.0