[PATCH 3/3] iommu/exynos: Add proper runtime pm support

[Marek Szyprowski]

This patch uses recently introduced runtime pm notifiers to track the
runtime pm state of the master's device. This way each SYSMMU controller
knows when its master's device is active and can save/restore its state
instead of being enabled all the time. This way SYSMMU controllers no
longer prevents respective power domains to be turned off when master's
device is not used.

Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
 drivers/iommu/exynos-iommu.c | 211 +++++++++++++++++++++----------------------
 1 file changed, 101 insertions(+), 110 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index 9d1a14f88891..de4126787c41 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -25,6 +25,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/dma-iommu.h>
+#include <linux/pm_domain.h>
 
 typedef u32 sysmmu_iova_t;
 typedef u32 sysmmu_pte_t;
@@ -233,13 +234,14 @@ struct sysmmu_drvdata {
 	struct clk *aclk;		/* SYSMMU's aclk clock */
 	struct clk *pclk;		/* SYSMMU's pclk clock */
 	struct clk *clk_master;		/* master's device clock */
-	int activations;		/* number of calls to sysmmu_enable */
 	spinlock_t lock;		/* lock for modyfying state */
+	int active;			/* current status */
 	struct exynos_iommu_domain *domain; /* domain we belong to */
 	struct list_head domain_node;	/* node for domain clients list */
 	struct list_head owner_node;	/* node for owner controllers list */
 	phys_addr_t pgtable;		/* assigned page table structure */
 	unsigned int version;		/* our version */
+	struct notifier_block pm_nb;	/* for tracking master's runtime pm */
 };
 
 static struct exynos_iommu_domain *to_exynos_domain(struct iommu_domain *dom)
@@ -247,25 +249,6 @@ static struct exynos_iommu_domain *to_exynos_domain(struct iommu_domain *dom)
 	return container_of(dom, struct exynos_iommu_domain, domain);
 }
 
-static bool set_sysmmu_active(struct sysmmu_drvdata *data)
-{
-	/* return true if the System MMU was not active previously
-	   and it needs to be initialized */
-	return ++data->activations == 1;
-}
-
-static bool set_sysmmu_inactive(struct sysmmu_drvdata *data)
-{
-	/* return true if the System MMU is needed to be disabled */
-	BUG_ON(data->activations < 1);
-	return --data->activations == 0;
-}
-
-static bool is_sysmmu_active(struct sysmmu_drvdata *data)
-{
-	return data->activations > 0;
-}
-
 static void sysmmu_unblock(struct sysmmu_drvdata *data)
 {
 	writel(CTRL_ENABLE, data->sfrbase + REG_MMU_CTRL);
@@ -384,7 +367,7 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
 	unsigned short reg_status, reg_clear;
 	int ret = -ENOSYS;
 
-	WARN_ON(!is_sysmmu_active(data));
+	WARN_ON(!data->active);
 
 	if (MMU_MAJ_VER(data->version) < 5) {
 		reg_status = REG_INT_STATUS;
@@ -440,32 +423,6 @@ static void __sysmmu_disable_nocount(struct sysmmu_drvdata *data)
 	__sysmmu_disable_clocks(data);
 }
 
-static bool __sysmmu_disable(struct sysmmu_drvdata *data)
-{
-	bool disabled;
-	unsigned long flags;
-
-	spin_lock_irqsave(&data->lock, flags);
-
-	disabled = set_sysmmu_inactive(data);
-
-	if (disabled) {
-		data->pgtable = 0;
-		data->domain = NULL;
-
-		__sysmmu_disable_nocount(data);
-
-		dev_dbg(data->sysmmu, "Disabled\n");
-	} else  {
-		dev_dbg(data->sysmmu, "%d times left to disable\n",
-					data->activations);
-	}
-
-	spin_unlock_irqrestore(&data->lock, flags);
-
-	return disabled;
-}
-
 static void __sysmmu_init_config(struct sysmmu_drvdata *data)
 {
 	unsigned int cfg;
@@ -501,34 +458,6 @@ static void __sysmmu_enable_nocount(struct sysmmu_drvdata *data)
 	clk_disable(data->clk_master);
 }
 
-static int __sysmmu_enable(struct sysmmu_drvdata *data, phys_addr_t pgtable,
-			   struct exynos_iommu_domain *domain)
-{
-	int ret = 0;
-	unsigned long flags;
-
-	spin_lock_irqsave(&data->lock, flags);
-	if (set_sysmmu_active(data)) {
-		data->pgtable = pgtable;
-		data->domain = domain;
-
-		__sysmmu_enable_nocount(data);
-
-		dev_dbg(data->sysmmu, "Enabled\n");
-	} else {
-		ret = (pgtable == data->pgtable) ? 1 : -EBUSY;
-
-		dev_dbg(data->sysmmu, "already enabled\n");
-	}
-
-	if (WARN_ON(ret < 0))
-		set_sysmmu_inactive(data); /* decrement count */
-
-	spin_unlock_irqrestore(&data->lock, flags);
-
-	return ret;
-}
-
 static void sysmmu_tlb_invalidate_flpdcache(struct sysmmu_drvdata *data,
 					    sysmmu_iova_t iova)
 {
@@ -536,7 +465,7 @@ static void sysmmu_tlb_invalidate_flpdcache(struct sysmmu_drvdata *data,
 
 
 	spin_lock_irqsave(&data->lock, flags);
-	if (is_sysmmu_active(data) && data->version >= MAKE_MMU_VER(3, 3)) {
+	if (data->active && data->version >= MAKE_MMU_VER(3, 3)) {
 		clk_enable(data->clk_master);
 		__sysmmu_tlb_invalidate_entry(data, iova, 1);
 		clk_disable(data->clk_master);
@@ -551,7 +480,7 @@ static void sysmmu_tlb_invalidate_entry(struct sysmmu_drvdata *data,
 	unsigned long flags;
 
 	spin_lock_irqsave(&data->lock, flags);
-	if (is_sysmmu_active(data)) {
+	if (data->active) {
 		unsigned int num_inv = 1;
 
 		clk_enable(data->clk_master);
@@ -580,6 +509,60 @@ static void sysmmu_tlb_invalidate_entry(struct sysmmu_drvdata *data,
 
 static struct iommu_ops exynos_iommu_ops;
 
+static void sysmmu_restore_state(struct sysmmu_drvdata *data)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&data->lock, flags);
+	if (data->master) {
+		pm_runtime_disable(data->sysmmu);
+		pm_runtime_set_active(data->sysmmu);
+		pm_runtime_enable(data->sysmmu);
+		__sysmmu_enable_nocount(data);
+		data->active = true;
+	}
+	spin_unlock_irqrestore(&data->lock, flags);
+}
+
+static void sysmmu_save_state(struct sysmmu_drvdata *data)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&data->lock, flags);
+	if (data->master) {
+		__sysmmu_disable_nocount(data);
+		pm_runtime_disable(data->sysmmu);
+		pm_runtime_set_suspended(data->sysmmu);
+		pm_runtime_enable(data->sysmmu);
+		data->active = false;
+	}
+	spin_unlock_irqrestore(&data->lock, flags);
+
+}
+
+static int sysmmu_runtime_genpd_event(struct notifier_block *this,
+				unsigned long event, void *ptr)
+{
+	struct sysmmu_drvdata *data = container_of(this, struct sysmmu_drvdata,
+						   pm_nb);
+
+	switch (event) {
+
+	case RPM_EVENT_RESUME_PRE:
+		dev_dbg(data->sysmmu, "restoring state on %s device pm request\n",
+			dev_name(data->master));
+		sysmmu_restore_state(data);
+		break;
+	case RPM_EVENT_SUSPEND_POST:
+		dev_dbg(data->sysmmu, "saving state on %s device pm request\n",
+			dev_name(data->master));
+		sysmmu_save_state(data);
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
 static int __init exynos_sysmmu_probe(struct platform_device *pdev)
 {
 	int irq, ret;
@@ -639,6 +622,7 @@ static int __init exynos_sysmmu_probe(struct platform_device *pdev)
 		return PTR_ERR(data->clk_master);
 
 	data->sysmmu = dev;
+	data->pm_nb.notifier_call = sysmmu_runtime_genpd_event;
 	spin_lock_init(&data->lock);
 
 	platform_set_drvdata(pdev, data);
@@ -651,6 +635,7 @@ static int __init exynos_sysmmu_probe(struct platform_device *pdev)
 			PG_ENT_SHIFT = SYSMMU_V5_PG_ENT_SHIFT;
 	}
 
+	pm_runtime_no_callbacks(dev);
 	pm_runtime_enable(dev);
 
 	of_iommu_set_ops(dev->of_node, &exynos_iommu_ops);
@@ -664,10 +649,9 @@ static int exynos_sysmmu_suspend(struct device *dev)
 	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
 
 	dev_dbg(dev, "suspend\n");
-	if (is_sysmmu_active(data)) {
+	if (data->active)
 		__sysmmu_disable_nocount(data);
-		pm_runtime_put(dev);
-	}
+
 	return 0;
 }
 
@@ -676,10 +660,9 @@ static int exynos_sysmmu_resume(struct device *dev)
 	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
 
 	dev_dbg(dev, "resume\n");
-	if (is_sysmmu_active(data)) {
-		pm_runtime_get_sync(dev);
+	if (data->active)
 		__sysmmu_enable_nocount(data);
-	}
+
 	return 0;
 }
 #endif
@@ -789,8 +772,11 @@ static void exynos_iommu_domain_free(struct iommu_domain *iommu_domain)
 	spin_lock_irqsave(&domain->lock, flags);
 
 	list_for_each_entry_safe(data, next, &domain->clients, domain_node) {
-		if (__sysmmu_disable(data))
-			data->master = NULL;
+		if (data->active)
+			sysmmu_save_state(data);
+		data->master = NULL;
+		data->pgtable = 0;
+		data->domain = NULL;
 		list_del_init(&data->domain_node);
 	}
 
@@ -830,20 +816,27 @@ static void exynos_iommu_detach_device(struct iommu_domain *iommu_domain,
 	if (!has_sysmmu(dev) || owner->domain != iommu_domain)
 		return;
 
+	list_for_each_entry(data, &owner->controllers, owner_node) {
+		pm_runtime_unregister_notifier(dev, &data->pm_nb);
+		if (pm_runtime_enabled(dev) && pm_runtime_active(dev))
+			sysmmu_save_state(data);
+	}
+
 	spin_lock_irqsave(&domain->lock, flags);
 	list_for_each_entry_safe(data, next, &domain->clients, domain_node) {
+		spin_lock(&data->lock);
 		if (data->master == dev) {
-			if (__sysmmu_disable(data)) {
-				data->master = NULL;
-				list_del_init(&data->domain_node);
-			}
-			pm_runtime_put(data->sysmmu);
 			found = true;
+			data->master = NULL;
+			data->pgtable = 0;
+			data->domain = NULL;
+			list_del_init(&data->domain_node);
 		}
+		spin_unlock(&data->lock);
 	}
+	owner->domain = NULL;
 	spin_unlock_irqrestore(&domain->lock, flags);
 
-	owner->domain = NULL;
 
 	if (found)
 		dev_dbg(dev, "%s: Detached IOMMU with pgtable %pa\n",
@@ -860,7 +853,6 @@ static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
 	struct sysmmu_drvdata *data;
 	phys_addr_t pagetable = virt_to_phys(domain->pgtable);
 	unsigned long flags;
-	int ret = -ENODEV;
 
 	if (!has_sysmmu(dev))
 		return -ENODEV;
@@ -868,29 +860,28 @@ static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
 	if (owner->domain)
 		exynos_iommu_detach_device(owner->domain, dev);
 
+	spin_lock_irqsave(&domain->lock, flags);
 	list_for_each_entry(data, &owner->controllers, owner_node) {
-		pm_runtime_get_sync(data->sysmmu);
-		ret = __sysmmu_enable(data, pagetable, domain);
-		if (ret >= 0) {
-			data->master = dev;
-
-			spin_lock_irqsave(&domain->lock, flags);
-			list_add_tail(&data->domain_node, &domain->clients);
-			spin_unlock_irqrestore(&domain->lock, flags);
-		}
+		spin_lock(&data->lock);
+		data->master = dev;
+		data->pgtable = pagetable;
+		data->domain = domain;
+		list_add_tail(&data->domain_node, &domain->clients);
+		spin_unlock(&data->lock);
 	}
+	owner->domain = iommu_domain;
+	spin_unlock_irqrestore(&domain->lock, flags);
 
-	if (ret < 0) {
-		dev_err(dev, "%s: Failed to attach IOMMU with pgtable %pa\n",
-					__func__, &pagetable);
-		return ret;
-	}
+	dev_dbg(dev, "%s: Attached IOMMU with pgtable %pa\n",
+		__func__, &pagetable);
 
-	owner->domain = iommu_domain;
-	dev_dbg(dev, "%s: Attached IOMMU with pgtable %pa %s\n",
-		__func__, &pagetable, (ret == 0) ? "" : ", again");
+	list_for_each_entry(data, &owner->controllers, owner_node) {
+		pm_runtime_register_notifier(dev, &data->pm_nb);
+		if (pm_runtime_enabled(dev) && pm_runtime_active(dev))
+			sysmmu_restore_state(data);
+	}
 
-	return ret;
+	return 0;
 }
 
 static sysmmu_pte_t *alloc_lv2entry(struct exynos_iommu_domain *domain,
-- 
1.9.2