sh: TMU: Basic runtime PM support

Modify the SH TMU clock source/clock event device driver to support
runtime PM at a basic level (i.e. device clocks can be disabled and
enabled, but domain power must be on, because the devices have to
be marked as "irq safe").

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>

drivers/clocksource/sh_tmu.c

@@ -45,6 +45,7 @@ struct sh_tmu_priv {
 	struct clock_event_device ced;
 	struct clocksource cs;
 	bool cs_enabled;
+	unsigned int enable_count;
 };
 
 static DEFINE_RAW_SPINLOCK(sh_tmu_lock);
@@ -109,7 +110,7 @@ static void sh_tmu_start_stop_ch(struct sh_tmu_priv *p, int start)
 	raw_spin_unlock_irqrestore(&sh_tmu_lock, flags);
 }
 
-static int sh_tmu_enable(struct sh_tmu_priv *p)
+static int __sh_tmu_enable(struct sh_tmu_priv *p)
 {
 	int ret;
 
@@ -137,7 +138,18 @@ static int sh_tmu_enable(struct sh_tmu_priv *p)
 	return 0;
 }
 
-static void sh_tmu_disable(struct sh_tmu_priv *p)
+static int sh_tmu_enable(struct sh_tmu_priv *p)
+{
+	if (p->enable_count++ > 0)
+		return 0;
+
+	pm_runtime_get_sync(&p->pdev->dev);
+	dev_pm_syscore_device(&p->pdev->dev, true);
+
+	return __sh_tmu_enable(p);
+}
+
+static void __sh_tmu_disable(struct sh_tmu_priv *p)
 {
 	/* disable channel */
 	sh_tmu_start_stop_ch(p, 0);
@@ -149,6 +161,20 @@ static void sh_tmu_disable(struct sh_tmu_priv *p)
 	clk_disable(p->clk);
 }
 
+static void sh_tmu_disable(struct sh_tmu_priv *p)
+{
+	if (WARN_ON(p->enable_count == 0))
+		return;
+
+	if (--p->enable_count > 0)
+		return;
+
+	__sh_tmu_disable(p);
+
+	dev_pm_syscore_device(&p->pdev->dev, false);
+	pm_runtime_put(&p->pdev->dev);
+}
+
 static void sh_tmu_set_next(struct sh_tmu_priv *p, unsigned long delta,
 			    int periodic)
 {
@@ -205,19 +231,24 @@ static int sh_tmu_clocksource_enable(struct clocksource *cs)
 	struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
 	int ret;
 
+	if (WARN_ON(p->cs_enabled))
+		return 0;
+
 	ret = sh_tmu_enable(p);
 	if (!ret) {
 		__clocksource_updatefreq_hz(cs, p->rate);
 		p->cs_enabled = true;
 	}
+
 	return ret;
 }
 
 static void sh_tmu_clocksource_disable(struct clocksource *cs)
 {
 	struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
 
-	WARN_ON(!p->cs_enabled);
+	if (WARN_ON(!p->cs_enabled))
+		return;
 
 	sh_tmu_disable(p);
 	p->cs_enabled = false;
@@ -227,19 +258,26 @@ static void sh_tmu_clocksource_suspend(struct clocksource *cs)
 {
 	struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
 
-	if (p->cs_enabled)
-		sh_tmu_disable(p);
+	if (!p->cs_enabled)
+		return;
 
-	pm_genpd_syscore_poweroff(&p->pdev->dev);
+	if (--p->enable_count == 0) {
+		__sh_tmu_disable(p);
+		pm_genpd_syscore_poweroff(&p->pdev->dev);
+	}
 }
 
 static void sh_tmu_clocksource_resume(struct clocksource *cs)
 {
 	struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
 
-	pm_genpd_syscore_poweron(&p->pdev->dev);
-	if (p->cs_enabled)
-		sh_tmu_enable(p);
+	if (!p->cs_enabled)
+		return;
+
+	if (p->enable_count++ == 0) {
+		pm_genpd_syscore_poweron(&p->pdev->dev);
+		__sh_tmu_enable(p);
+	}
 }
 
 static int sh_tmu_register_clocksource(struct sh_tmu_priv *p,
@@ -434,6 +472,8 @@ static int sh_tmu_setup(struct sh_tmu_priv *p, struct platform_device *pdev)
 		ret = PTR_ERR(p->clk);
 		goto err1;
 	}
+	p->cs_enabled = false;
+	p->enable_count = 0;
 
 	return sh_tmu_register(p, (char *)dev_name(&p->pdev->dev),
 			       cfg->clockevent_rating,
@@ -447,18 +487,17 @@ static int sh_tmu_setup(struct sh_tmu_priv *p, struct platform_device *pdev)
 static int __devinit sh_tmu_probe(struct platform_device *pdev)
 {
 	struct sh_tmu_priv *p = platform_get_drvdata(pdev);
+	struct sh_timer_config *cfg = pdev->dev.platform_data;
 	int ret;
 
 	if (!is_early_platform_device(pdev)) {
-		struct sh_timer_config *cfg = pdev->dev.platform_data;
-
-		if (cfg->clocksource_rating || cfg->clockevent_rating)
-			dev_pm_syscore_device(&pdev->dev, true);
+		pm_runtime_set_active(&pdev->dev);
+		pm_runtime_enable(&pdev->dev);
 	}
 
 	if (p) {
 		dev_info(&pdev->dev, "kept as earlytimer\n");
-		return 0;
+		goto out;
 	}
 
 	p = kmalloc(sizeof(*p), GFP_KERNEL);
@@ -471,8 +510,19 @@ static int __devinit sh_tmu_probe(struct platform_device *pdev)
 	if (ret) {
 		kfree(p);
 		platform_set_drvdata(pdev, NULL);
+		pm_runtime_idle(&pdev->dev);
+		return ret;
 	}
-	return ret;
+	if (is_early_platform_device(pdev))
+		return 0;
+
+ out:
+	if (cfg->clockevent_rating || cfg->clocksource_rating)
+		pm_runtime_irq_safe(&pdev->dev);
+	else
+		pm_runtime_idle(&pdev->dev);
+
+	return 0;
 }
 
 static int __devexit sh_tmu_remove(struct platform_device *pdev)