staging: mt7621-gpio: fix masks for gpio pin

BIT macro is being used to get mask for gpio's pin
which is retrieved using 'hwirq' from struct irq_data.
The problem here is that 'hwirq' can be as large as 95,
and 1UL << 95 is unlikely to work well. Instead of using
BIT macro use a new PIN_MASK macro which takes into account
pin and WIDTH of the bank in order to make a proper mask for
the gpio pin. Also 'd->hwirq' has been replaced by 'pin' in
some places because there was a 'pin' variable in changed
functions with the proper value. This improves readability.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-gpio/gpio-mt7621.c

@@ -16,6 +16,7 @@
 
 #define MTK_BANK_CNT		3
 #define MTK_BANK_WIDTH		32
+#define PIN_MASK(nr)		(1UL << ((nr % MTK_BANK_WIDTH)))
 
 enum mediatek_gpio_reg {
 	GPIO_REG_CTRL = 0,
@@ -239,8 +240,8 @@ mediatek_gpio_irq_unmask(struct irq_data *d)
 	fall = mtk_gpio_r32(rg, GPIO_REG_FEDGE);
 
 	spin_lock_irqsave(&rg->lock, flags);
-	mtk_gpio_w32(rg, GPIO_REG_REDGE, rise | (BIT(d->hwirq) & rg->rising));
-	mtk_gpio_w32(rg, GPIO_REG_FEDGE, fall | (BIT(d->hwirq) & rg->falling));
+	mtk_gpio_w32(rg, GPIO_REG_REDGE, rise | (PIN_MASK(pin) & rg->rising));
+	mtk_gpio_w32(rg, GPIO_REG_FEDGE, fall | (PIN_MASK(pin) & rg->falling));
 	spin_unlock_irqrestore(&rg->lock, flags);
 }
 
@@ -261,8 +262,8 @@ mediatek_gpio_irq_mask(struct irq_data *d)
 	fall = mtk_gpio_r32(rg, GPIO_REG_FEDGE);
 
 	spin_lock_irqsave(&rg->lock, flags);
-	mtk_gpio_w32(rg, GPIO_REG_FEDGE, fall & ~BIT(d->hwirq));
-	mtk_gpio_w32(rg, GPIO_REG_REDGE, rise & ~BIT(d->hwirq));
+	mtk_gpio_w32(rg, GPIO_REG_FEDGE, fall & ~PIN_MASK(pin));
+	mtk_gpio_w32(rg, GPIO_REG_REDGE, rise & ~PIN_MASK(pin));
 	spin_unlock_irqrestore(&rg->lock, flags);
 }
 
@@ -273,7 +274,7 @@ mediatek_gpio_irq_type(struct irq_data *d, unsigned int type)
 	int pin = d->hwirq;
 	int bank = pin / MTK_BANK_WIDTH;
 	struct mtk_gc *rg = gpio_data->gc_map[bank];
-	u32 mask = BIT(d->hwirq);
+	u32 mask = PIN_MASK(pin);
 
 	if (!rg)
 		return -1;