platform-msi: Factor out allocation/free of private data

As we're going to have multiple paths to allocate/free the
platform-msi private data, factor this out into separate
utility functions.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/base/platform-msi.c

@@ -189,21 +189,11 @@ struct irq_domain *platform_msi_create_irq_domain(struct fwnode_handle *fwnode,
 	return domain;
 }
 
-/**
- * platform_msi_domain_alloc_irqs - Allocate MSI interrupts for @dev
- * @dev:		The device for which to allocate interrupts
- * @nvec:		The number of interrupts to allocate
- * @write_msi_msg:	Callback to write an interrupt message for @dev
- *
- * Returns:
- * Zero for success, or an error code in case of failure
- */
-int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
+static struct platform_msi_priv_data *
+platform_msi_alloc_priv_data(struct device *dev, unsigned int nvec,
 			     irq_write_msi_msg_t write_msi_msg)
 {
-	struct platform_msi_priv_data *priv_data;
-	int err;
-
+	struct platform_msi_priv_data *datap;
 	/*
 	 * Limit the number of interrupts to 256 per device. Should we
 	 * need to bump this up, DEV_ID_SHIFT should be adjusted
@@ -211,33 +201,62 @@ int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
 	 * capable devices).
 	 */
 	if (!dev->msi_domain || !write_msi_msg || !nvec || nvec > MAX_DEV_MSIS)
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 
 	if (dev->msi_domain->bus_token != DOMAIN_BUS_PLATFORM_MSI) {
 		dev_err(dev, "Incompatible msi_domain, giving up\n");
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 	}
 
 	/* Already had a helping of MSI? Greed... */
 	if (!list_empty(dev_to_msi_list(dev)))
-		return -EBUSY;
+		return ERR_PTR(-EBUSY);
 
-	priv_data = kzalloc(sizeof(*priv_data), GFP_KERNEL);
-	if (!priv_data)
-		return -ENOMEM;
+	datap = kzalloc(sizeof(*datap), GFP_KERNEL);
+	if (!datap)
+		return ERR_PTR(-ENOMEM);
 
-	priv_data->devid = ida_simple_get(&platform_msi_devid_ida,
+	datap->devid = ida_simple_get(&platform_msi_devid_ida,
 				      0, 1 << DEV_ID_SHIFT, GFP_KERNEL);
-	if (priv_data->devid < 0) {
-		err = priv_data->devid;
-		goto out_free_data;
+	if (datap->devid < 0) {
+		int err = datap->devid;
+		kfree(datap);
+		return ERR_PTR(err);
 	}
 
-	priv_data->write_msg = write_msi_msg;
+	datap->write_msg = write_msi_msg;
+
+	return datap;
+}
+
+static void platform_msi_free_priv_data(struct platform_msi_priv_data *data)
+{
+	ida_simple_remove(&platform_msi_devid_ida, data->devid);
+	kfree(data);
+}
+
+/**
+ * platform_msi_domain_alloc_irqs - Allocate MSI interrupts for @dev
+ * @dev:		The device for which to allocate interrupts
+ * @nvec:		The number of interrupts to allocate
+ * @write_msi_msg:	Callback to write an interrupt message for @dev
+ *
+ * Returns:
+ * Zero for success, or an error code in case of failure
+ */
+int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
+				   irq_write_msi_msg_t write_msi_msg)
+{
+	struct platform_msi_priv_data *priv_data;
+	int err;
+
+	priv_data = platform_msi_alloc_priv_data(dev, nvec, write_msi_msg);
+	if (IS_ERR(priv_data))
+		return PTR_ERR(priv_data);
 
 	err = platform_msi_alloc_descs(dev, nvec, priv_data);
 	if (err)
-		goto out_free_id;
+		goto out_free_priv_data;
 
 	err = msi_domain_alloc_irqs(dev->msi_domain, dev, nvec);
 	if (err)
@@ -247,10 +266,8 @@ int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
 
 out_free_desc:
 	platform_msi_free_descs(dev, 0, nvec);
-out_free_id:
-	ida_simple_remove(&platform_msi_devid_ida, priv_data->devid);
-out_free_data:
-	kfree(priv_data);
+out_free_priv_data:
+	platform_msi_free_priv_data(priv_data);
 
 	return err;
 }
@@ -261,16 +278,11 @@ int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
  */
 void platform_msi_domain_free_irqs(struct device *dev)
 {
+	if (!list_empty(dev_to_msi_list(dev))) {
 		struct msi_desc *desc;
 
 		desc = first_msi_entry(dev);
-	if (desc) {
-		struct platform_msi_priv_data *data;
-
-		data = desc->platform.msi_priv_data;
-
-		ida_simple_remove(&platform_msi_devid_ida, data->devid);
-		kfree(data);
+		platform_msi_free_priv_data(desc->platform.msi_priv_data);
 	}
 
 	msi_domain_free_irqs(dev->msi_domain, dev);