ahci_platform: Provide for vendor specific init

Some AHCI implementations may use Vendor Specific HBA[A0h, FFh]
and/or Port[70h, 7Fh] registers to 'prepare' for initialization.
For that, the platform needs memory mapped address of AHCI registers.

This patch adds the 'mmio' argument and reorders the call to
platform init function.

Signed-off-by: Jassi Brar <jassi.brar@samsung.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/ata/ahci_platform.c b/drivers/ata/ahci_platform.c
index 5e11b16..68ef6b5 100644
--- a/drivers/ata/ahci_platform.c
+++ b/drivers/ata/ahci_platform.c
@@ -54,19 +54,13 @@
 		return -EINVAL;
 	}
 
-	if (pdata && pdata->init) {
-		rc = pdata->init(dev);
-		if (rc)
-			return rc;
-	}
-
 	if (pdata && pdata->ata_port_info)
 		pi = *pdata->ata_port_info;
 
 	hpriv = devm_kzalloc(dev, sizeof(*hpriv), GFP_KERNEL);
 	if (!hpriv) {
-		rc = -ENOMEM;
-		goto err0;
+		dev_err(dev, "can't alloc ahci_host_priv\n");
+		return -ENOMEM;
 	}
 
 	hpriv->flags |= (unsigned long)pi.private_data;
@@ -74,8 +68,19 @@
 	hpriv->mmio = devm_ioremap(dev, mem->start, resource_size(mem));
 	if (!hpriv->mmio) {
 		dev_err(dev, "can't map %pR\n", mem);
-		rc = -ENOMEM;
-		goto err0;
+		return -ENOMEM;
+	}
+
+	/*
+	 * Some platforms might need to prepare for mmio region access,
+	 * which could be done in the following init call. So, the mmio
+	 * region shouldn't be accessed before init (if provided) has
+	 * returned successfully.
+	 */
+	if (pdata && pdata->init) {
+		rc = pdata->init(dev, hpriv->mmio);
+		if (rc)
+			return rc;
 	}
 
 	ahci_save_initial_config(dev, hpriv,