ahci: Cache host controller version

This allows sysfs nodes to read the cached value directly instead of
powering up possibly runtime suspended controller.

Signed-off-by: Mika Westerberg <[e-mail]>
Signed-off-by: Tejun Heo <[e-mail]>

drivers/ata/ahci.h

···
 	void __iomem *		mmio;		/* bus-independent mem map */
 	u32			cap;		/* cap to use */
 	u32			cap2;		/* cap2 to use */
+	u32			version;	/* cached version */
 	u32			port_map;	/* port map to use */
 	u32			saved_cap;	/* saved initial cap */
 	u32			saved_cap2;	/* saved initial cap2 */

drivers/ata/libahci.c

···
 	struct Scsi_Host *shost = class_to_shost(dev);
 	struct ata_port *ap = ata_shost_to_port(shost);
 	struct ahci_host_priv *hpriv = ap->host->private_data;
-	void __iomem *mmio = hpriv->mmio;
 
-	return sprintf(buf, "%x\n", readl(mmio + HOST_VERSION));
+	return sprintf(buf, "%x\n", hpriv->version);
 }
 
 static ssize_t ahci_show_port_cmd(struct device *dev,
···
 	/* record values to use during operation */
 	hpriv->cap = cap;
 	hpriv->cap2 = cap2;
+	hpriv->version = readl(mmio + HOST_VERSION);
 	hpriv->port_map = port_map;
 
 	if (!hpriv->start_engine)
···
 void ahci_print_info(struct ata_host *host, const char *scc_s)
 {
 	struct ahci_host_priv *hpriv = host->private_data;
-	void __iomem *mmio = hpriv->mmio;
 	u32 vers, cap, cap2, impl, speed;
 	const char *speed_s;
 
-	vers = readl(mmio + HOST_VERSION);
+	vers = hpriv->version;
 	cap = hpriv->cap;
 	cap2 = hpriv->cap2;
 	impl = hpriv->port_map;