libata: stop overloading port_info->private_data

port_info->private_data is currently used for two purposes - to record
private data about the port_info or to specify host->private_data to
use when allocating ata_host.

This overloading is confusing and counter-intuitive in that
port_info->private_data becomes host->private_data instead of
port->private_data.  In addition, port_info and host don't correspond
to each other 1-to-1.  Currently, the first non-NULL
port_info->private_data is used.

This patch makes port_info->private_data just be what it is -
private_data for the port_info where LLD can jot down extra info.
libata no longer sets host->private_data to the first non-NULL
port_info->private_data, @host_priv argument is added to
ata_pci_init_one() instead.  LLDs which use ata_pci_init_one() can use
this argument to pass in pointer to host private data.  LLDs which
don't should use init-register model anyway and can initialize
host->private_data directly.

Adding @host_priv instead of using init-register model for LLDs which
use ata_pci_init_one() is suggested by Alan Cox.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index a9d5898..6223ec0 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -827,6 +827,7 @@
  *	@pdev: Controller to be initialized
  *	@ppi: array of port_info, must be enough for two ports
  *	@sht: scsi_host_template to use when registering the host
+ *	@host_priv: host private_data
  *
  *	This is a helper function which can be called from a driver's
  *	xxx_init_one() probe function if the hardware uses traditional
@@ -848,7 +849,7 @@
  */
 int ata_pci_init_one(struct pci_dev *pdev,
 		     const struct ata_port_info * const * ppi,
-		     struct scsi_host_template *sht)
+		     struct scsi_host_template *sht, void *host_priv)
 {
 	struct device *dev = &pdev->dev;
 	const struct ata_port_info *pi = NULL;
@@ -882,6 +883,7 @@
 	rc = ata_pci_prepare_sff_host(pdev, ppi, &host);
 	if (rc)
 		goto out;
+	host->private_data = host_priv;
 
 	pci_set_master(pdev);
 	rc = ata_pci_activate_sff_host(host, ata_interrupt, sht);