hwmon: (nct6775) Rearrange attr-group initialization

We now track the number of attribute groups in nct6775_data, as a
measure to simplify handling differences in the set of enabled
attribute groups between nct6775 drivers (platform & i2c).  As a side
effect, we also reduce the amount of IS_ERR()/PTR_ERR() boilerplate a
bit.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20220427010154.29749-4-zev@bewilderbeest.net
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/nct6775.c

@@ -1199,6 +1199,7 @@ struct nct6775_data {
 	const char *name;
 
 	const struct attribute_group *groups[7];
+	u8 num_groups;
 
 	u16 reg_temp[5][NUM_TEMP]; /* 0=temp, 1=temp_over, 2=temp_hyst,
 				    * 3=temp_crit, 4=temp_lcrit
@@ -1404,10 +1405,18 @@ struct sensor_template_group {
 	int base;
 };
 
-static struct attribute_group *
-nct6775_create_attr_group(struct device *dev,
-			  const struct sensor_template_group *tg,
-			  int repeat)
+static int nct6775_add_attr_group(struct nct6775_data *data, const struct attribute_group *group)
+{
+	/* Need to leave a NULL terminator at the end of data->groups */
+	if (data->num_groups == ARRAY_SIZE(data->groups) - 1)
+		return -ENOBUFS;
+
+	data->groups[data->num_groups++] = group;
+	return 0;
+}
+
+static int nct6775_add_template_attr_group(struct device *dev, struct nct6775_data *data,
+					   const struct sensor_template_group *tg, int repeat)
 {
 	struct attribute_group *group;
 	struct sensor_device_attr_u *su;
@@ -1418,28 +1427,28 @@ nct6775_create_attr_group(struct device *dev,
 	int i, count;
 
 	if (repeat <= 0)
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 
 	t = tg->templates;
 	for (count = 0; *t; t++, count++)
 		;
 
 	if (count == 0)
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 
 	group = devm_kzalloc(dev, sizeof(*group), GFP_KERNEL);
 	if (group == NULL)
-		return ERR_PTR(-ENOMEM);
+		return -ENOMEM;
 
 	attrs = devm_kcalloc(dev, repeat * count + 1, sizeof(*attrs),
 			     GFP_KERNEL);
 	if (attrs == NULL)
-		return ERR_PTR(-ENOMEM);
+		return -ENOMEM;
 
 	su = devm_kzalloc(dev, array3_size(repeat, count, sizeof(*su)),
 			       GFP_KERNEL);
 	if (su == NULL)
-		return ERR_PTR(-ENOMEM);
+		return -ENOMEM;
 
 	group->attrs = attrs;
 	group->is_visible = tg->is_visible;
@@ -1477,7 +1486,7 @@ nct6775_create_attr_group(struct device *dev,
 		}
 	}
 
-	return group;
+	return nct6775_add_attr_group(data, group);
 }
 
 static bool is_word_sized(struct nct6775_data *data, u16 reg)
@@ -4316,11 +4325,9 @@ static int nct6775_probe(struct platform_device *pdev)
 	const u16 *reg_temp_crit_l = NULL, *reg_temp_crit_h = NULL;
 	int num_reg_temp, num_reg_temp_mon, num_reg_tsi_temp;
 	u8 cr2a;
-	struct attribute_group *group;
 	struct device *hwmon_dev;
 	struct sensor_template_group tsi_temp_tg;
 	const struct regmap_config *regmapcfg;
-	int num_attr_groups = 0;
 
 	if (sio_data->access == access_direct) {
 		res = platform_get_resource(pdev, IORESOURCE_IO, 0);
@@ -5165,46 +5172,39 @@ static int nct6775_probe(struct platform_device *pdev)
 		return err;
 
 	/* Register sysfs hooks */
-	group = nct6775_create_attr_group(dev, &nct6775_pwm_template_group,
-					  data->pwm_num);
-	if (IS_ERR(group))
-		return PTR_ERR(group);
-
-	data->groups[num_attr_groups++] = group;
-
-	group = nct6775_create_attr_group(dev, &nct6775_in_template_group,
-					  fls(data->have_in));
-	if (IS_ERR(group))
-		return PTR_ERR(group);
-
-	data->groups[num_attr_groups++] = group;
-
-	group = nct6775_create_attr_group(dev, &nct6775_fan_template_group,
-					  fls(data->has_fan));
-	if (IS_ERR(group))
-		return PTR_ERR(group);
+	err = nct6775_add_template_attr_group(dev, data, &nct6775_pwm_template_group,
+					      data->pwm_num);
+	if (err)
+		return err;
 
-	data->groups[num_attr_groups++] = group;
+	err = nct6775_add_template_attr_group(dev, data, &nct6775_in_template_group,
+					      fls(data->have_in));
+	if (err)
+		return err;
 
-	group = nct6775_create_attr_group(dev, &nct6775_temp_template_group,
-					  fls(data->have_temp));
-	if (IS_ERR(group))
-		return PTR_ERR(group);
+	err = nct6775_add_template_attr_group(dev, data, &nct6775_fan_template_group,
+					      fls(data->has_fan));
+	if (err)
+		return err;
 
-	data->groups[num_attr_groups++] = group;
+	err = nct6775_add_template_attr_group(dev, data, &nct6775_temp_template_group,
+					      fls(data->have_temp));
+	if (err)
+		return err;
 
 	if (data->have_tsi_temp) {
 		tsi_temp_tg.templates = nct6775_tsi_temp_template;
 		tsi_temp_tg.is_visible = nct6775_tsi_temp_is_visible;
 		tsi_temp_tg.base = fls(data->have_temp) + 1;
-		group = nct6775_create_attr_group(dev, &tsi_temp_tg, fls(data->have_tsi_temp));
-		if (IS_ERR(group))
-			return PTR_ERR(group);
-
-		data->groups[num_attr_groups++] = group;
+		err = nct6775_add_template_attr_group(dev, data, &tsi_temp_tg,
+						      fls(data->have_tsi_temp));
+		if (err)
+			return err;
 	}
 
-	data->groups[num_attr_groups++] = &nct6775_group_other;
+	err = nct6775_add_attr_group(data, &nct6775_group_other);
+	if (err)
+		return err;
 
 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, data->name,
 							   data, data->groups);