gpio/mpc8xxx: change irq handler from chained to normal

More than one gpio controllers can share one interrupt, change the
driver to request shared irq.

While this will work, it will mess up userspace accounting of the number
of interrupts per second in tools such as vmstat.  The reason is that
for every GPIO interrupt, /proc/interrupts records the count against GIC
interrupt 68 or 69, as well as the GPIO itself.  So, for every GPIO
interrupt, the total number of interrupts that the system has seen
increments by two.

Signed-off-by: Laurentiu Tudor <Laurentiu.Tudor@nxp.com>
Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Signed-off-by: Song Hui <hui.song_1@nxp.com>
Link: https://lore.kernel.org/r/20191011005643.41007-1-hui.song_1@nxp.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-mpc8xxx.c

@@ -22,6 +22,7 @@
 #include <linux/irq.h>
 #include <linux/gpio/driver.h>
 #include <linux/bitops.h>
+#include <linux/interrupt.h>
 
 #define MPC8XXX_GPIO_PINS	32
 
@@ -127,20 +128,19 @@ static int mpc8xxx_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
 		return -ENXIO;
 }
 
-static void mpc8xxx_gpio_irq_cascade(struct irq_desc *desc)
+static irqreturn_t mpc8xxx_gpio_irq_cascade(int irq, void *data)
 {
-	struct mpc8xxx_gpio_chip *mpc8xxx_gc = irq_desc_get_handler_data(desc);
-	struct irq_chip *chip = irq_desc_get_chip(desc);
+	struct mpc8xxx_gpio_chip *mpc8xxx_gc = data;
 	struct gpio_chip *gc = &mpc8xxx_gc->gc;
-	unsigned int mask;
+	unsigned long mask;
+	int i;
 
 	mask = gc->read_reg(mpc8xxx_gc->regs + GPIO_IER)
 		& gc->read_reg(mpc8xxx_gc->regs + GPIO_IMR);
-	if (mask)
-		generic_handle_irq(irq_linear_revmap(mpc8xxx_gc->irq,
-						     32 - ffs(mask)));
-	if (chip->irq_eoi)
-		chip->irq_eoi(&desc->irq_data);
+	for_each_set_bit(i, &mask, 32)
+		generic_handle_irq(irq_linear_revmap(mpc8xxx_gc->irq, 31 - i));
+
+	return IRQ_HANDLED;
 }
 
 static void mpc8xxx_irq_unmask(struct irq_data *d)
@@ -409,8 +409,16 @@ static int mpc8xxx_probe(struct platform_device *pdev)
 	if (devtype->gpio_dir_in_init)
 		devtype->gpio_dir_in_init(gc);
 
-	irq_set_chained_handler_and_data(mpc8xxx_gc->irqn,
-					 mpc8xxx_gpio_irq_cascade, mpc8xxx_gc);
+	ret = devm_request_irq(&pdev->dev, mpc8xxx_gc->irqn,
+			       mpc8xxx_gpio_irq_cascade,
+			       IRQF_NO_THREAD | IRQF_SHARED, "gpio-cascade",
+			       mpc8xxx_gc);
+	if (ret) {
+		dev_err(&pdev->dev, "%s: failed to devm_request_irq(%d), ret = %d\n",
+			np->full_name, mpc8xxx_gc->irqn, ret);
+		goto err;
+	}
+
 	return 0;
 err:
 	iounmap(mpc8xxx_gc->regs);