scsi: g_NCR5380: Fix automatic IRQ on HP C2502 cards

When IRQ_AUTO is used, the interrupt for HP C2502 cards gets disabled.
Fix this by programming the card for a suitable free irq. The code for
the free irq search comes from ALSA.

Also allow IRQ 9 to work (it aliases to IRQ 2 on the card), as per
Ondrej Zary's patch.

Suggested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 57 insertions, 13 deletions

diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
index 6d245a7b9363..58a0b826eb51 100644
--- a/drivers/scsi/g_NCR5380.c
+++ b/drivers/scsi/g_NCR5380.c
@@ -131,14 +131,33 @@ static void magic_configure(int idx, u8 irq, u8 magic[])
         outb(magic[3], 0x379);
         outb(magic[4], 0x379);
 
-        /* allowed IRQs for HP C2502 */
-        if (irq != 2 && irq != 3 && irq != 4 && irq != 5 && irq != 7)
-                irq = 0;
+        if (irq == 9)
+                irq = 2;
+
         if (idx >= 0 && idx <= 7)
                 cfg = 0x80 | idx | (irq << 4);
         outb(cfg, 0x379);
 }
 
+static irqreturn_t legacy_empty_irq_handler(int irq, void *dev_id)
+{
+        return IRQ_HANDLED;
+}
+
+static int legacy_find_free_irq(int *irq_table)
+{
+        while (*irq_table != -1) {
+                if (!request_irq(*irq_table, legacy_empty_irq_handler,
+                                 IRQF_PROBE_SHARED, "Test IRQ",
+                                 (void *)irq_table)) {
+                        free_irq(*irq_table, (void *) irq_table);
+                        return *irq_table;
+                }
+                irq_table++;
+        }
+        return -1;
+}
+
 static unsigned int ncr_53c400a_ports[] = {
         0x280, 0x290, 0x300, 0x310, 0x330, 0x340, 0x348, 0x350, 0
 };
@@ -151,6 +170,9 @@ static u8 ncr_53c400a_magic[] = {	/* 53C400A & DTC436 */
 static u8 hp_c2502_magic[] = {  /* HP C2502 */
         0x0f, 0x22, 0xf0, 0x20, 0x80
 };
+static int hp_c2502_irqs[] = {
+        9, 5, 7, 3, 4, -1
+};
 
 static int generic_NCR5380_init_one(struct scsi_host_template *tpnt,
                         struct device *pdev, int base, int irq, int board)
@@ -319,19 +341,41 @@ static int generic_NCR5380_init_one(struct scsi_host_template *tpnt,
 
         NCR5380_maybe_reset_bus(instance);
 
-        if (irq != IRQ_AUTO)
-                instance->irq = irq;
-        else
-                instance->irq = g_NCR5380_probe_irq(instance);
-
         /* Compatibility with documented NCR5380 kernel parameters */
-        if (instance->irq == 255)
-                instance->irq = NO_IRQ;
+        if (irq == 255 || irq == 0)
+                irq = NO_IRQ;
+
+        if (board == BOARD_HP_C2502) {
+                int *irq_table = hp_c2502_irqs;
+                int board_irq = -1;
+
+                switch (irq) {
+                case NO_IRQ:
+                        board_irq = 0;
+                        break;
+                case IRQ_AUTO:
+                        board_irq = legacy_find_free_irq(irq_table);
+                        break;
+                default:
+                        while (*irq_table != -1)
+                                if (*irq_table++ == irq)
+                                        board_irq = irq;
+                }
+
+                if (board_irq <= 0) {
+                        board_irq = 0;
+                        irq = NO_IRQ;
+                }
+
+                magic_configure(port_idx, board_irq, magic);
+        }
+
+        if (irq == IRQ_AUTO)
+                instance->irq = g_NCR5380_probe_irq(instance);
+        else
+                instance->irq = irq;
 
         if (instance->irq != NO_IRQ) {
-                /* set IRQ for HP C2502 */
-                if (board == BOARD_HP_C2502)
-                        magic_configure(port_idx, instance->irq, magic);
                 if (request_irq(instance->irq, generic_NCR5380_intr,
                                 0, "NCR5380", instance)) {
                         printk(KERN_WARNING "scsi%d : IRQ%d not free, interrupts disabled\n", instance->host_no, instance->irq);