iommu/sprd: Add support for reattaching an existing domain

This IOMMU driver should allow a domain to be attached more than once.

If IOMMU is reattaching to the same domain which is attached, there's
nothing to be done.

If reattching to a previously-used domain, do not alloc DMA buffer
again which stores address mapping table to avoid memory leak.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lore.kernel.org/r/20230331033124.864691-3-zhang.lyra@gmail.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
index 7df1f73..3513b2b 100644 (file)
--- a/drivers/iommu/sprd-iommu.c
+++ b/drivers/iommu/sprd-iommu.c
@@ -62,6 +62,7 @@ enum sprd_iommu_version {
  * @eb: gate clock which controls IOMMU access
  */
 struct sprd_iommu_device {
+       struct sprd_iommu_domain        *dom;
        enum sprd_iommu_version ver;
        u32                     *prot_page_va;
        dma_addr_t              prot_page_pa;
@@ -252,15 +253,27 @@ static int sprd_iommu_attach_device(struct iommu_domain *domain,
        struct sprd_iommu_domain *dom = to_sprd_domain(domain);
        size_t pgt_size = sprd_iommu_pgt_size(domain);
 
-       if (dom->sdev)
-               return -EINVAL;
+       /* The device is attached to this domain */
+       if (sdev->dom == dom)
+               return 0;
 
-       dom->pgt_va = dma_alloc_coherent(sdev->dev, pgt_size, &dom->pgt_pa, GFP_KERNEL);
-       if (!dom->pgt_va)
-               return -ENOMEM;
+       /* The first time that domain is attaching to a device */
+       if (!dom->pgt_va) {
+               dom->pgt_va = dma_alloc_coherent(sdev->dev, pgt_size, &dom->pgt_pa, GFP_KERNEL);
+               if (!dom->pgt_va)
+                       return -ENOMEM;
+
+               dom->sdev = sdev;
+       }
 
-       dom->sdev = sdev;
+       sdev->dom = dom;
 
+       /*
+        * One sprd IOMMU serves one client device only, disabled it before
+        * configure mapping table to avoid access conflict in case other
+        * mapping table is stored in.
+        */
+       sprd_iommu_hw_en(sdev, false);
        sprd_iommu_first_ppn(dom);
        sprd_iommu_first_vpn(dom);
        sprd_iommu_vpn_range(dom);