mfd: Flag WM831x /IRQ as a wake source

The WM831x can generate wake events, some unconditionally, so flag
the primary IRQ as a wake source in order to help the CPU treat the
/IRQ signal appropriately.

Signed-off-by: Mark Brown <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

drivers/mfd/wm831x-irq.c

···
 		return 0;
 	}
 
+	/* Try to flag /IRQ as a wake source; there are a number of
+	 * unconditional wake sources in the PMIC so this isn't
+	 * conditional but we don't actually care *too* much if it
+	 * fails.
+	 */
+	ret = enable_irq_wake(irq);
+	if (ret != 0) {
+		dev_warn(wm831x->dev, "Can't enable IRQ as wake source: %d\n",
+			 ret);
+	}
+
 	wm831x->irq = irq;
 	wm831x->irq_base = pdata->irq_base;