irqchip: renesas-irqc: Add minimal runtime PM support

This is just enough to let pm_clk_*() enable the functional clock, and
manage it for suspend/resume, if present.
Before, it was assumed enabled by the bootloader or reset state.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Link: https://lkml.kernel.org/r/1426704961-27322-3-git-send-email-geert+renesas@glider.be
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-renesas-irqc.c

@@ -29,6 +29,7 @@
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/platform_data/irq-renesas-irqc.h>
+#include <linux/pm_runtime.h>
 
 #define IRQC_IRQ_MAX	32	/* maximum 32 interrupts per driver instance */
 
@@ -180,6 +181,9 @@ static int irqc_probe(struct platform_device *pdev)
 	p->pdev = pdev;
 	platform_set_drvdata(pdev, p);
 
+	pm_runtime_enable(&pdev->dev);
+	pm_runtime_get_sync(&pdev->dev);
+
 	/* get hold of manadatory IOMEM */
 	io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!io) {
@@ -260,6 +264,8 @@ static int irqc_probe(struct platform_device *pdev)
 err2:
 	iounmap(p->iomem);
 err1:
+	pm_runtime_put(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
 	kfree(p);
 err0:
 	return ret;
@@ -275,6 +281,8 @@ static int irqc_remove(struct platform_device *pdev)
 
 	irq_domain_remove(p->irq_domain);
 	iounmap(p->iomem);
+	pm_runtime_put(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
 	kfree(p);
 	return 0;
 }