pata_hpt3x2n: check channel enable bits

The driver's prereset() method still doesn't check the channel enable bits.
The bug was there for the entire time the driver has existed. :-/

Alan Cox fixed the HPT37x driver in commit b5bf24b ("[PATCH] hpt37x:
Check the enablebits") but forgot to check the HPT3x2N driver which has
the same bug. :-/

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

drivers/ata/pata_hpt3x2n.c

@@ -24,7 +24,7 @@
 #include <linux/libata.h>
 
 #define DRV_NAME	"pata_hpt3x2n"
-#define DRV_VERSION	"0.3.15"
+#define DRV_VERSION	"0.3.16"
 
 enum {
 	HPT_PCI_FAST	=	(1 << 31),
@@ -168,6 +168,13 @@ static int hpt3x2n_pre_reset(struct ata_link *link, unsigned long deadline)
 {
 	struct ata_port *ap = link->ap;
 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
+	static const struct pci_bits hpt3x2n_enable_bits[] = {
+		{ 0x50, 1, 0x04, 0x04 },
+		{ 0x54, 1, 0x04, 0x04 }
+	};
+
+	if (!pci_test_config_bits(pdev, &hpt3x2n_enable_bits[ap->port_no]))
+		return -ENOENT;
 
 	/* Reset the state machine */
 	pci_write_config_byte(pdev, 0x50 + 4 * ap->port_no, 0x37);