sata_promise: disable hotplug on 1st gen chips

1st generation Promise SATA chips are prone to generating spurious
hotplug events which can disrupt normal operation. This has been
observed on 20376 and 20378 chips. This patch thus disables hotplug
support on 1st gen chips while leaving it enabled for 2nd gen chips.

The pdc_sata_hotplug_offset() function becomes redundant so it is
removed.

Tested on 1st gen 20376 and 20378 mainboard chips and on a 2nd gen
SATA300 PCI card.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Tested-by: Kurt Roeckx <kurt@roeckx.be>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_promise.c

@@ -195,9 +195,12 @@ static struct ata_port_operations pdc_sata_ops = {
 	.hardreset		= pdc_sata_hardreset,
 };
 
-/* First-generation chips need a more restrictive ->check_atapi_dma op */
+/* First-generation chips need a more restrictive ->check_atapi_dma op,
+   and ->freeze/thaw that ignore the hotplug controls. */
 static struct ata_port_operations pdc_old_sata_ops = {
 	.inherits		= &pdc_sata_ops,
+	.freeze			= pdc_freeze,
+	.thaw			= pdc_thaw,
 	.check_atapi_dma	= pdc_old_sata_check_atapi_dma,
 };
 
@@ -626,11 +629,6 @@ static unsigned int pdc_sata_ata_port_to_ata_no(const struct ata_port *ap)
 	return pdc_port_no_to_ata_no(i, pdc_is_sataii_tx4(ap->flags));
 }
 
-static unsigned int pdc_sata_hotplug_offset(const struct ata_port *ap)
-{
-	return (ap->flags & PDC_FLAG_GEN_II) ? PDC2_SATA_PLUG_CSR : PDC_SATA_PLUG_CSR;
-}
-
 static void pdc_freeze(struct ata_port *ap)
 {
 	void __iomem *ata_mmio = ap->ioaddr.cmd_addr;
@@ -647,7 +645,7 @@ static void pdc_sata_freeze(struct ata_port *ap)
 {
 	struct ata_host *host = ap->host;
 	void __iomem *host_mmio = host->iomap[PDC_MMIO_BAR];
-	unsigned int hotplug_offset = pdc_sata_hotplug_offset(ap);
+	unsigned int hotplug_offset = PDC2_SATA_PLUG_CSR;
 	unsigned int ata_no = pdc_sata_ata_port_to_ata_no(ap);
 	u32 hotplug_status;
 
@@ -685,7 +683,7 @@ static void pdc_sata_thaw(struct ata_port *ap)
 {
 	struct ata_host *host = ap->host;
 	void __iomem *host_mmio = host->iomap[PDC_MMIO_BAR];
-	unsigned int hotplug_offset = pdc_sata_hotplug_offset(ap);
+	unsigned int hotplug_offset = PDC2_SATA_PLUG_CSR;
 	unsigned int ata_no = pdc_sata_ata_port_to_ata_no(ap);
 	u32 hotplug_status;
 
@@ -832,14 +830,14 @@ static irqreturn_t pdc_interrupt(int irq, void *dev_instance)
 	spin_lock(&host->lock);
 
 	/* read and clear hotplug flags for all ports */
-	if (host->ports[0]->flags & PDC_FLAG_GEN_II)
+	if (host->ports[0]->flags & PDC_FLAG_GEN_II) {
 		hotplug_offset = PDC2_SATA_PLUG_CSR;
-	else
-		hotplug_offset = PDC_SATA_PLUG_CSR;
-	hotplug_status = readl(host_mmio + hotplug_offset);
-	if (hotplug_status & 0xff)
-		writel(hotplug_status | 0xff, host_mmio + hotplug_offset);
-	hotplug_status &= 0xff;	/* clear uninteresting bits */
+		hotplug_status = readl(host_mmio + hotplug_offset);
+		if (hotplug_status & 0xff)
+			writel(hotplug_status | 0xff, host_mmio + hotplug_offset);
+		hotplug_status &= 0xff;	/* clear uninteresting bits */
+	} else
+		hotplug_status = 0;
 
 	/* reading should also clear interrupts */
 	mask = readl(host_mmio + PDC_INT_SEQMASK);
@@ -1034,9 +1032,11 @@ static void pdc_host_init(struct ata_host *host)
 	tmp = readl(host_mmio + hotplug_offset);
 	writel(tmp | 0xff, host_mmio + hotplug_offset);
 
-	/* unmask plug/unplug ints */
 	tmp = readl(host_mmio + hotplug_offset);
-	writel(tmp & ~0xff0000, host_mmio + hotplug_offset);
+	if (is_gen2)	/* unmask plug/unplug ints */
+		writel(tmp & ~0xff0000, host_mmio + hotplug_offset);
+	else		/* mask plug/unplug ints */
+		writel(tmp | 0xff0000, host_mmio + hotplug_offset);
 
 	/* don't initialise TBG or SLEW on 2nd generation chips */
 	if (is_gen2)