gpio: davinci: don't create irq_domain in case of unbanked irqs

The system may crash if:
- there are more than 1 banks
- unbanked irqs are enabled
- someone will call gpio_to_irq() for GPIO from bank2 or above

Hence, fix it by not creating irq_domain if unbanked irqs are enabled
and correct gpio_to_irq_banked() to handle this properly.

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Sekhar Nori <nsekhar@ti.com>

Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>

drivers/gpio/gpio-davinci.c

@@ -351,7 +351,10 @@ static int gpio_to_irq_banked(struct gpio_chip *chip, unsigned offset)
 {
 	struct davinci_gpio_controller *d = chip2controller(chip);
 
-	return irq_create_mapping(d->irq_domain, d->chip.base + offset);
+	if (d->irq_domain)
+		return irq_create_mapping(d->irq_domain, d->chip.base + offset);
+	else
+		return -ENXIO;
 }
 
 static int gpio_to_irq_unbanked(struct gpio_chip *chip, unsigned offset)
@@ -429,7 +432,7 @@ static int davinci_gpio_irq_setup(struct platform_device *pdev)
 	struct davinci_gpio_controller *chips = platform_get_drvdata(pdev);
 	struct davinci_gpio_platform_data *pdata = dev->platform_data;
 	struct davinci_gpio_regs __iomem *g;
-	struct irq_domain	*irq_domain;
+	struct irq_domain	*irq_domain = NULL;
 
 	ngpio = pdata->ngpio;
 	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
@@ -453,18 +456,20 @@ static int davinci_gpio_irq_setup(struct platform_device *pdev)
 	}
 	clk_prepare_enable(clk);
 
-	irq = irq_alloc_descs(-1, 0, ngpio, 0);
-	if (irq < 0) {
-		dev_err(dev, "Couldn't allocate IRQ numbers\n");
-		return irq;
-	}
+	if (!pdata->gpio_unbanked) {
+		irq = irq_alloc_descs(-1, 0, ngpio, 0);
+		if (irq < 0) {
+			dev_err(dev, "Couldn't allocate IRQ numbers\n");
+			return irq;
+		}
 
-	irq_domain = irq_domain_add_legacy(NULL, ngpio, irq, 0,
-						&davinci_gpio_irq_ops,
-						chips);
-	if (!irq_domain) {
-		dev_err(dev, "Couldn't register an IRQ domain\n");
-		return -ENODEV;
+		irq_domain = irq_domain_add_legacy(NULL, ngpio, irq, 0,
+							&davinci_gpio_irq_ops,
+							chips);
+		if (!irq_domain) {
+			dev_err(dev, "Couldn't register an IRQ domain\n");
+			return -ENODEV;
+		}
 	}
 
 	/*
@@ -475,8 +480,7 @@ static int davinci_gpio_irq_setup(struct platform_device *pdev)
 	 */
 	for (gpio = 0, bank = 0; gpio < ngpio; bank++, gpio += 32) {
 		chips[bank].chip.to_irq = gpio_to_irq_banked;
-		if (!pdata->gpio_unbanked)
-			chips[bank].irq_domain = irq_domain;
+		chips[bank].irq_domain = irq_domain;
 	}
 
 	/*