irqchip/renesas-irqc: Use wakeup_path i.s.o. explicit clock handling

Since commit 6f46aedb9c85873b ("irqchip: renesas-irqc: Add wake-up
support"), when an IRQ is used for wakeup, the INTC
block's module clock is manually kept running during system suspend, to
make sure the device stays active.

However, this explicit clock handling is merely a workaround for a
failure to properly communicate wakeup information to the device core.

Instead, set the device's power.wakeup_path field, to indicate this
device is part of the wakeup path.  Depending on the PM Domain's
active_wakeup configuration, the genpd core code will keep the device
enabled (and the clock running) during system suspend when needed.
This allows for the removal of all explicit clock handling code from the
driver.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-renesas-irqc.c

@@ -17,7 +17,6 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#include <linux/clk.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
@@ -64,7 +63,7 @@ struct irqc_priv {
 	struct platform_device *pdev;
 	struct irq_chip_generic *gc;
 	struct irq_domain *irq_domain;
-	struct clk *clk;
+	atomic_t wakeup_path;
 };
 
 static struct irqc_priv *irq_data_to_priv(struct irq_data *data)
@@ -111,14 +110,10 @@ static int irqc_irq_set_wake(struct irq_data *d, unsigned int on)
 	int hw_irq = irqd_to_hwirq(d);
 
 	irq_set_irq_wake(p->irq[hw_irq].requested_irq, on);
-
-	if (!p->clk)
-		return 0;
-
 	if (on)
-		clk_enable(p->clk);
+		atomic_inc(&p->wakeup_path);
 	else
-		clk_disable(p->clk);
+		atomic_dec(&p->wakeup_path);
 
 	return 0;
 }
@@ -159,12 +154,6 @@ static int irqc_probe(struct platform_device *pdev)
 	p->pdev = pdev;
 	platform_set_drvdata(pdev, p);
 
-	p->clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(p->clk)) {
-		dev_warn(&pdev->dev, "unable to get clock\n");
-		p->clk = NULL;
-	}
-
 	pm_runtime_enable(&pdev->dev);
 	pm_runtime_get_sync(&pdev->dev);
 
@@ -276,6 +265,18 @@ static int irqc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int __maybe_unused irqc_suspend(struct device *dev)
+{
+	struct irqc_priv *p = dev_get_drvdata(dev);
+
+	if (atomic_read(&p->wakeup_path))
+		device_set_wakeup_path(dev);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(irqc_pm_ops, irqc_suspend, NULL);
+
 static const struct of_device_id irqc_dt_ids[] = {
 	{ .compatible = "renesas,irqc", },
 	{},
@@ -288,6 +289,7 @@ static struct platform_driver irqc_device_driver = {
 	.driver		= {
 		.name	= "renesas_irqc",
 		.of_match_table	= irqc_dt_ids,
+		.pm	= &irqc_pm_ops,
 	}
 };