gpio: mxc: release the parent IRQ in runtime suspend

Release the parent interrupt request during runtime suspend, allowing
the parent interrupt controller to enter runtime suspend if there are
no active users.

This change may not have a visible impact if the parent controller is
the GIC, but it can enable significant power savings for parent IRQ
controllers like IRQSteer inside a subsystem on i.MX8 SoCs. Releasing
the parent IRQ provides an opportunity for the subsystem to enter suspend
states if there are no active users.

Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpio-mxc.c

@@ -62,6 +62,7 @@ struct mxc_gpio_port {
 	struct clk *clk;
 	int irq;
 	int irq_high;
+	void (*mx_irq_handler)(struct irq_desc *desc);
 	struct irq_domain *domain;
 	struct gpio_chip gc;
 	struct device *dev;
@@ -399,6 +400,24 @@ static void mxc_gpio_free(struct gpio_chip *chip, unsigned int offset)
 	pm_runtime_put(chip->parent);
 }
 
+static void mxc_update_irq_chained_handler(struct mxc_gpio_port *port, bool enable)
+{
+	if (enable)
+		irq_set_chained_handler_and_data(port->irq, port->mx_irq_handler, port);
+	else
+		irq_set_chained_handler_and_data(port->irq, NULL, NULL);
+
+	/* setup handler for GPIO 16 to 31 */
+	if (port->irq_high > 0) {
+		if (enable)
+			irq_set_chained_handler_and_data(port->irq_high,
+							 port->mx_irq_handler,
+							 port);
+		else
+			irq_set_chained_handler_and_data(port->irq_high, NULL, NULL);
+	}
+}
+
 static int mxc_gpio_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
@@ -460,18 +479,12 @@ static int mxc_gpio_probe(struct platform_device *pdev)
 		 * the handler is needed only once, but doing it for every port
 		 * is more robust and easier.
 		 */
-		irq_set_chained_handler(port->irq, mx2_gpio_irq_handler);
-	} else {
-		/* setup one handler for each entry */
-		irq_set_chained_handler_and_data(port->irq,
-						 mx3_gpio_irq_handler, port);
-		if (port->irq_high > 0)
-			/* setup handler for GPIO 16 to 31 */
-			irq_set_chained_handler_and_data(port->irq_high,
-							 mx3_gpio_irq_handler,
-							 port);
-	}
+		port->irq_high = -1;
+		port->mx_irq_handler = mx2_gpio_irq_handler;
+	} else
+		port->mx_irq_handler = mx3_gpio_irq_handler;
 
+	mxc_update_irq_chained_handler(port, true);
 	err = bgpio_init(&port->gc, &pdev->dev, 4,
 			 port->base + GPIO_PSR,
 			 port->base + GPIO_DR, NULL,
@@ -604,6 +617,7 @@ static int mxc_gpio_runtime_suspend(struct device *dev)
 
 	mxc_gpio_save_regs(port);
 	clk_disable_unprepare(port->clk);
+	mxc_update_irq_chained_handler(port, false);
 
 	return 0;
 }
@@ -613,9 +627,12 @@ static int mxc_gpio_runtime_resume(struct device *dev)
 	struct mxc_gpio_port *port = dev_get_drvdata(dev);
 	int ret;
 
+	mxc_update_irq_chained_handler(port, true);
 	ret = clk_prepare_enable(port->clk);
-	if (ret)
+	if (ret) {
+		mxc_update_irq_chained_handler(port, false);
 		return ret;
+	}
 
 	mxc_gpio_restore_regs(port);