Re: [PATCH v3] iommu/rockchip: Add missing set_platform_dma_ops callback

Signed-off-by: Steven Price <steven.price@arm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
---
Changes since v2[1]:

  * Fixed suspend/resume handlers to check against rk_identity_domain
    rather than NULL (thanks John).

[1] https://lore.kernel.org/r/20230324111127.221640-1-steven.price%40arm.com

  drivers/iommu/rockchip-iommu.c | 56 +++++++++++++++++++++++++---------
  1 file changed, 42 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index f30db22ea5d7..4f97af471671 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c

@@ -124,6 +124,7 @@ struct rk_iommudata {
  
  static struct device *dma_dev;
  static const struct rk_iommu_ops *rk_ops;
+static struct iommu_domain rk_identity_domain;
  
  static inline void rk_table_flush(struct rk_iommu_domain *dom, dma_addr_t dma,
  				  unsigned int count)

@@ -646,7 +647,7 @@ static irqreturn_t rk_iommu_irq(int irq, void *dev_id)
  			 * Ignore the return code, though, since we always zap cache
  			 * and clear the page fault anyway.
  			 */
-			if (iommu->domain)
+			if (iommu->domain != &rk_identity_domain)
  				report_iommu_fault(iommu->domain, iommu->dev, iova,
  						   flags);
  			else

@@ -980,26 +981,27 @@ static int rk_iommu_enable(struct rk_iommu *iommu)
  	return ret;
  }
  
-static void rk_iommu_detach_device(struct iommu_domain *domain,
-				   struct device *dev)
+static int rk_iommu_identity_attach(struct iommu_domain *identity_domain,
+				    struct device *dev)
  {
  	struct rk_iommu *iommu;
-	struct rk_iommu_domain *rk_domain = to_rk_domain(domain);
+	struct rk_iommu_domain *rk_domain;
  	unsigned long flags;
  	int ret;
  
  	/* Allow 'virtual devices' (eg drm) to detach from domain */
  	iommu = rk_iommu_from_dev(dev);
  	if (!iommu)
-		return;
+		return -ENODEV;
+
+	rk_domain = to_rk_domain(iommu->domain);
  
  	dev_dbg(dev, "Detaching from iommu domain\n");
  
-	/* iommu already detached */
-	if (iommu->domain != domain)
-		return;
+	if (iommu->domain == identity_domain)
+		return 0;
  
-	iommu->domain = NULL;
+	iommu->domain = identity_domain;
  
  	spin_lock_irqsave(&rk_domain->iommus_lock, flags);
  	list_del_init(&iommu->node);

@@ -1011,7 +1013,25 @@ static void rk_iommu_detach_device(struct iommu_domain *domain,
  		rk_iommu_disable(iommu);
  		pm_runtime_put(iommu->dev);
  	}
+
+	return 0;
+}
+
+static struct iommu_domain_ops rk_identity_ops = {
+	.attach_dev = rk_iommu_identity_attach,

+};
+
+static struct iommu_domain rk_identity_domain = {
+	.type = IOMMU_DOMAIN_IDENTITY,
+	.ops = &rk_identity_ops,
+};
+
+#ifdef CONFIG_ARM
+static void rk_iommu_set_platform_dma(struct device *dev)
+{
+	WARN_ON(rk_iommu_identity_attach(&rk_identity_domain, dev));
  }
+#endif
  
  static int rk_iommu_attach_device(struct iommu_domain *domain,
  		struct device *dev)

@@ -1035,8 +1055,9 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
  	if (iommu->domain == domain)
  		return 0;
  
-	if (iommu->domain)
-		rk_iommu_detach_device(iommu->domain, dev);
+	ret = rk_iommu_identity_attach(&rk_identity_domain, dev);
+	if (ret)
+		return ret;
  
  	iommu->domain = domain;
  

@@ -1050,7 +1071,7 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
  
  	ret = rk_iommu_enable(iommu);
  	if (ret)
-		rk_iommu_detach_device(iommu->domain, dev);
+		WARN_ON(rk_iommu_identity_attach(&rk_identity_domain, dev));
  
  	pm_runtime_put(iommu->dev);
  

@@ -1061,6 +1082,9 @@ static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)
  {
  	struct rk_iommu_domain *rk_domain;
  
+	if (type == IOMMU_DOMAIN_IDENTITY)
+		return &rk_identity_domain;
+
  	if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
  		return NULL;
  

@@ -1176,6 +1200,7 @@ static int rk_iommu_of_xlate(struct device *dev,
  	iommu_dev = of_find_device_by_node(args->np);
  
  	data->iommu = platform_get_drvdata(iommu_dev);
+	data->iommu->domain = &rk_identity_domain;
  	dev_iommu_priv_set(dev, data);
  
  	platform_device_put(iommu_dev);

@@ -1188,6 +1213,9 @@ static const struct iommu_ops rk_iommu_ops = {
  	.probe_device = rk_iommu_probe_device,
  	.release_device = rk_iommu_release_device,
  	.device_group = rk_iommu_device_group,
+#ifdef CONFIG_ARM
+	.set_platform_dma_ops = rk_iommu_set_platform_dma,
+#endif
  	.pgsize_bitmap = RK_IOMMU_PGSIZE_BITMAP,
  	.of_xlate = rk_iommu_of_xlate,
  	.default_domain_ops = &(const struct iommu_domain_ops) {

@@ -1343,7 +1371,7 @@ static int __maybe_unused rk_iommu_suspend(struct device *dev)
  {
  	struct rk_iommu *iommu = dev_get_drvdata(dev);
  
-	if (!iommu->domain)
+	if (iommu->domain == &rk_identity_domain)
  		return 0;
  
  	rk_iommu_disable(iommu);

@@ -1354,7 +1382,7 @@ static int __maybe_unused rk_iommu_resume(struct device *dev)
  {
  	struct rk_iommu *iommu = dev_get_drvdata(dev);
  
-	if (!iommu->domain)
+	if (iommu->domain == &rk_identity_domain)
  		return 0;
  
  	return rk_iommu_enable(iommu);