ahci: factor out AHCI enabling and enable AHCI before reading CAP

Factor out AHCI enabling into ahci_enable_ahci() and enabling AHCI
before reading CAP in ahci_save_initial_config() as the spec requires
enabling AHCI mode before accessing any other registers.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 49761bc12cf26b719337c8264512194000815d96..6f089b899a1a7e9587bbba731f9b9047e7c15eae 100644 (file)
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -597,6 +597,20 @@ static inline void __iomem *ahci_port_base(struct ata_port *ap)
        return __ahci_port_base(ap->host, ap->port_no);
 }
 
+static void ahci_enable_ahci(void __iomem *mmio)
+{
+       u32 tmp;
+
+       /* turn on AHCI_EN */
+       tmp = readl(mmio + HOST_CTL);
+       if (!(tmp & HOST_AHCI_EN)) {
+               tmp |= HOST_AHCI_EN;
+               writel(tmp, mmio + HOST_CTL);
+               tmp = readl(mmio + HOST_CTL);   /* flush && sanity check */
+               WARN_ON(!(tmp & HOST_AHCI_EN));
+       }
+}
+
 /**
  *     ahci_save_initial_config - Save and fixup initial config values
  *     @pdev: target PCI device
@@ -619,6 +633,9 @@ static void ahci_save_initial_config(struct pci_dev *pdev,
        u32 cap, port_map;
        int i;
 
+       /* make sure AHCI mode is enabled before accessing CAP */
+       ahci_enable_ahci(mmio);
+
        /* Values prefixed with saved_ are written back to host after
         * reset.  Values without are used for driver operation.
         */
@@ -1043,13 +1060,10 @@ static int ahci_reset_controller(struct ata_host *host)
        /* we must be in AHCI mode, before using anything
         * AHCI-specific, such as HOST_RESET.
         */
-       tmp = readl(mmio + HOST_CTL);
-       if (!(tmp & HOST_AHCI_EN)) {
-               tmp |= HOST_AHCI_EN;
-               writel(tmp, mmio + HOST_CTL);
-       }
+       ahci_enable_ahci(mmio);
 
        /* global controller reset */
+       tmp = readl(mmio + HOST_CTL);
        if ((tmp & HOST_RESET) == 0) {
                writel(tmp | HOST_RESET, mmio + HOST_CTL);
                readl(mmio + HOST_CTL); /* flush */
@@ -1068,8 +1082,7 @@ static int ahci_reset_controller(struct ata_host *host)
        }
 
        /* turn on AHCI mode */
-       writel(HOST_AHCI_EN, mmio + HOST_CTL);
-       (void) readl(mmio + HOST_CTL);  /* flush */
+       ahci_enable_ahci(mmio);
 
        /* some registers might be cleared on reset.  restore initial values */
        ahci_restore_initial_config(host);