mfd: Emulate active low IRQs as well as active high IRQs for wm831x

As with the existing emulation this should not be used in production
systems but is useful for test purposes.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/wm831x-irq.c b/drivers/mfd/wm831x-irq.c
index ecc9d6d..804e56e 100644
--- a/drivers/mfd/wm831x-irq.c
+++ b/drivers/mfd/wm831x-irq.c
@@ -413,22 +413,25 @@
 	 * do the update here as we can be called with the bus lock
 	 * held.
 	 */
+	wm831x->gpio_level_low[irq] = false;
+	wm831x->gpio_level_high[irq] = false;
 	switch (type) {
 	case IRQ_TYPE_EDGE_BOTH:
 		wm831x->gpio_update[irq] = 0x10000 | WM831X_GPN_INT_MODE;
-		wm831x->gpio_level[irq] = false;
 		break;
 	case IRQ_TYPE_EDGE_RISING:
 		wm831x->gpio_update[irq] = 0x10000 | WM831X_GPN_POL;
-		wm831x->gpio_level[irq] = false;
 		break;
 	case IRQ_TYPE_EDGE_FALLING:
 		wm831x->gpio_update[irq] = 0x10000;
-		wm831x->gpio_level[irq] = false;
 		break;
 	case IRQ_TYPE_LEVEL_HIGH:
 		wm831x->gpio_update[irq] = 0x10000 | WM831X_GPN_POL;
-		wm831x->gpio_level[irq] = true;
+		wm831x->gpio_level_high[irq] = true;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		wm831x->gpio_update[irq] = 0x10000;
+		wm831x->gpio_level_low[irq] = true;
 		break;
 	default:
 		return -EINVAL;
@@ -517,7 +520,7 @@
 		 * status.  This is sucky but improves interoperability.
 		 */
 		if (primary == WM831X_GP_INT &&
-		    wm831x->gpio_level[i - WM831X_IRQ_GPIO_1]) {
+		    wm831x->gpio_level_high[i - WM831X_IRQ_GPIO_1]) {
 			ret = wm831x_reg_read(wm831x, WM831X_GPIO_LEVEL);
 			while (ret & 1 << (i - WM831X_IRQ_GPIO_1)) {
 				handle_nested_irq(irq_find_mapping(wm831x->irq_domain,
@@ -526,6 +529,17 @@
 						      WM831X_GPIO_LEVEL);
 			}
 		}
+
+		if (primary == WM831X_GP_INT &&
+		    wm831x->gpio_level_low[i - WM831X_IRQ_GPIO_1]) {
+			ret = wm831x_reg_read(wm831x, WM831X_GPIO_LEVEL);
+			while (!(ret & 1 << (i - WM831X_IRQ_GPIO_1))) {
+				handle_nested_irq(irq_find_mapping(wm831x->irq_domain,
+								   i));
+				ret = wm831x_reg_read(wm831x,
+						      WM831X_GPIO_LEVEL);
+			}
+		}
 	}
 
 out: