base: soc: Handle custom soc information sysfs entries

Soc framework exposed sysfs entries are not sufficient for some
of the h/w platforms. Currently there is no interface where soc
drivers can expose further information about their SoCs via soc
framework. This change address this limitation where clients can
pass their custom entries as attribute group and soc framework
would expose them as sysfs properties.
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/1570480662-25252-1-git-send-email-mnalajal@codeaurora.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/soc.c

@@ -104,15 +104,12 @@ static const struct attribute_group soc_attr_group = {
 	.is_visible = soc_attribute_mode,
 };
 
-static const struct attribute_group *soc_attr_groups[] = {
-	&soc_attr_group,
-	NULL,
-};
-
 static void soc_release(struct device *dev)
 {
 	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
 
+	ida_simple_remove(&soc_ida, soc_dev->soc_dev_num);
+	kfree(soc_dev->dev.groups);
 	kfree(soc_dev);
 }
 
@@ -121,6 +118,7 @@ static struct soc_device_attribute *early_soc_dev_attr;
 struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
 {
 	struct soc_device *soc_dev;
+	const struct attribute_group **soc_attr_groups;
 	int ret;
 
 	if (!soc_bus_type.p) {
@@ -136,10 +134,18 @@ struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr
 		goto out1;
 	}
 
+	soc_attr_groups = kcalloc(3, sizeof(*soc_attr_groups), GFP_KERNEL);
+	if (!soc_attr_groups) {
+		ret = -ENOMEM;
+		goto out2;
+	}
+	soc_attr_groups[0] = &soc_attr_group;
+	soc_attr_groups[1] = soc_dev_attr->custom_attr_group;
+
 	/* Fetch a unique (reclaimable) SOC ID. */
 	ret = ida_simple_get(&soc_ida, 0, 0, GFP_KERNEL);
 	if (ret < 0)
-		goto out2;
+		goto out3;
 	soc_dev->soc_dev_num = ret;
 
 	soc_dev->attr = soc_dev_attr;
@@ -150,15 +156,15 @@ struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr
 	dev_set_name(&soc_dev->dev, "soc%d", soc_dev->soc_dev_num);
 
 	ret = device_register(&soc_dev->dev);
-	if (ret)
-		goto out3;
+	if (ret) {
+		put_device(&soc_dev->dev);
+		return ERR_PTR(ret);
+	}
 
 	return soc_dev;
 
 out3:
-	ida_simple_remove(&soc_ida, soc_dev->soc_dev_num);
-	put_device(&soc_dev->dev);
-	soc_dev = NULL;
+	kfree(soc_attr_groups);
 out2:
 	kfree(soc_dev);
 out1:
@@ -169,8 +175,6 @@ EXPORT_SYMBOL_GPL(soc_device_register);
 /* Ensure soc_dev->attr is freed prior to calling soc_device_unregister. */
 void soc_device_unregister(struct soc_device *soc_dev)
 {
-	ida_simple_remove(&soc_ida, soc_dev->soc_dev_num);
-
 	device_unregister(&soc_dev->dev);
 	early_soc_dev_attr = NULL;
 }

include/linux/sys_soc.h

@@ -15,6 +15,7 @@ struct soc_device_attribute {
 	const char *serial_number;
 	const char *soc_id;
 	const void *data;
+	const struct attribute_group *custom_attr_group;
 };
 
 /**