smc91c92_cs: fix the problem that lan & modem does not work simultaneously

smc91c92_cs:
  Fix the problem that lan & modem does not work simultaneously
  in the Megahertz multi-function card.
  We need to write MEGAHERTZ_ISR to retrigger interrupt.
Signed-off-by: NKen Kawasaki <ken_kawasaki@spring.nifty.jp>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/pcmcia/smc91c92_cs.c

@@ -1505,12 +1505,20 @@ static irqreturn_t smc_interrupt(int irq, void *dev_id)
 	writeb(cor & ~COR_IREQ_ENA, smc->base + MOT_LAN + CISREG_COR);
 	writeb(cor, smc->base + MOT_LAN + CISREG_COR);
     }
-#ifdef DOES_NOT_WORK
-    if (smc->base != NULL) { /* Megahertz MFC's */
-	readb(smc->base+MEGAHERTZ_ISR);
-	readb(smc->base+MEGAHERTZ_ISR);
+
+    if ((smc->base != NULL) &&  /* Megahertz MFC's */
+	(smc->manfid == MANFID_MEGAHERTZ) &&
+	(smc->cardid == PRODID_MEGAHERTZ_EM3288)) {
+
+	u_char tmp;
+	tmp = readb(smc->base+MEGAHERTZ_ISR);
+	tmp = readb(smc->base+MEGAHERTZ_ISR);
+
+	/* Retrigger interrupt if needed */
+	writeb(tmp, smc->base + MEGAHERTZ_ISR);
+	writeb(tmp, smc->base + MEGAHERTZ_ISR);
     }
-#endif
+
     spin_unlock(&smc->lock);
     return IRQ_RETVAL(handled);
 }