This patch dumps all active mapping entries from pagetable to a
debugfs directory named "mappings".

Attaching an example:

[SWGROUP: xusb_host] [as: (id: 5), (attr: R|W|-), (pd_dma: 0x0000000080005000)]
{
        [index: 1023] 0xf0080040 (count: 52)
        {
                PTE RANGE      | ATTR | PHYS               | IOVA               
| SIZE
                [#913 , #913 ] | 0x7  | 0x0000000102674000 | 0x00000000fff91000 
| 0x1000
                [#914 , #914 ] | 0x7  | 0x0000000102672000 | 0x00000000fff92000 
| 0x1000
                [#915 , #915 ] | 0x7  | 0x0000000102671000 | 0x00000000fff93000 
| 0x1000
                [#916 , #916 ] | 0x7  | 0x0000000102670000 | 0x00000000fff94000 
| 0x1000
                [#921 , #921 ] | 0x7  | 0x00000000fcc00000 | 0x00000000fff99000 
| 0x1000
                [#922 , #922 ] | 0x7  | 0x000000010266d000 | 0x00000000fff9a000 
| 0x1000
                [#923 , #923 ] | 0x7  | 0x000000010266c000 | 0x00000000fff9b000 
| 0x1000
                [#948 , #948 ] | 0x7  | 0x0000000102668000 | 0x00000000fffb4000 
| 0x1000
                [#949 , #949 ] | 0x7  | 0x0000000102667000 | 0x00000000fffb5000 
| 0x1000
                [#950 , #950 ] | 0x7  | 0x0000000102666000 | 0x00000000fffb6000 
| 0x1000
                [#951 , #951 ] | 0x7  | 0x0000000102665000 | 0x00000000fffb7000 
| 0x1000
                [#952 , #952 ] | 0x7  | 0x000000010264b000 | 0x00000000fffb8000 
| 0x1000
                [#953 , #953 ] | 0x7  | 0x000000010264a000 | 0x00000000fffb9000 
| 0x1000
                [#954 , #954 ] | 0x7  | 0x0000000102649000 | 0x00000000fffba000 
| 0x1000
                [#955 , #955 ] | 0x7  | 0x0000000102648000 | 0x00000000fffbb000 
| 0x1000
                [#956 , #956 ] | 0x7  | 0x000000010260f000 | 0x00000000fffbc000 
| 0x1000
                [#957 , #957 ] | 0x7  | 0x000000010260e000 | 0x00000000fffbd000 
| 0x1000
                [#958 , #958 ] | 0x7  | 0x000000010260d000 | 0x00000000fffbe000 
| 0x1000
                [#959 , #959 ] | 0x7  | 0x000000010260b000 | 0x00000000fffbf000 
| 0x1000
                [#960 , #992 ] | 0x7  | 0x00000001025ea000 | 0x00000000fffc0000 
| 0x21000
        }
}
Total PDEs: 1, total PTEs: 52

Note that the example above was output after I locally enabled
IOMMU_DOMAIN_DMA, which is not merged to mainline yet due to a
known framebuffer issue.

Signed-off-by: Nicolin Chen <nicol...@nvidia.com>
---
 drivers/iommu/tegra-smmu.c | 143 +++++++++++++++++++++++++++++++++++++
 1 file changed, 143 insertions(+)

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 1fbb93215463..575e82076270 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -46,6 +46,7 @@ struct tegra_smmu {
        struct list_head list;
 
        struct dentry *debugfs;
+       struct dentry *debugfs_mappings;
 
        struct iommu_device iommu;      /* IOMMU Core code handle */
 };
@@ -153,6 +154,9 @@ static inline u32 smmu_readl(struct tegra_smmu *smmu, 
unsigned long offset)
 
 #define SMMU_PDE_ATTR          (SMMU_PDE_READABLE | SMMU_PDE_WRITABLE | \
                                 SMMU_PDE_NONSECURE)
+#define SMMU_PTE_ATTR          (SMMU_PTE_READABLE | SMMU_PTE_WRITABLE | \
+                                SMMU_PTE_NONSECURE)
+#define SMMU_PTE_ATTR_SHIFT    29
 
 static unsigned int iova_pd_index(unsigned long iova)
 {
@@ -164,6 +168,12 @@ static unsigned int iova_pt_index(unsigned long iova)
        return (iova >> SMMU_PTE_SHIFT) & (SMMU_NUM_PTE - 1);
 }
 
+static unsigned long pd_pt_index_iova(unsigned int pd_index, unsigned int 
pt_index)
+{
+       return (pd_index & (SMMU_NUM_PDE - 1)) << SMMU_PDE_SHIFT |
+              (pt_index & (SMMU_NUM_PTE - 1)) << SMMU_PTE_SHIFT;
+}
+
 static bool smmu_dma_addr_valid(struct tegra_smmu *smmu, dma_addr_t addr)
 {
        addr >>= 12;
@@ -496,6 +506,125 @@ static void tegra_smmu_as_unprepare(struct tegra_smmu 
*smmu,
        mutex_unlock(&smmu->lock);
 }
 
+static int tegra_smmu_debugfs_mappings_show(struct seq_file *s, void *data)
+{
+       struct tegra_smmu_group *group = s->private;
+       const struct tegra_smmu_swgroup *swgrp;
+       struct tegra_smmu_as *as;
+       struct tegra_smmu *smmu;
+       unsigned int pd_index;
+       unsigned int pt_index;
+       unsigned long flags;
+       u64 pte_count = 0;
+       u32 pde_count = 0;
+       u32 *pd, val;
+
+       if (!group || !group->as || !group->swgrp)
+               return 0;
+
+       swgrp = group->swgrp;
+       smmu = group->smmu;
+       as = group->as;
+
+       mutex_lock(&smmu->lock);
+
+       val = smmu_readl(smmu, swgrp->reg) & SMMU_ASID_ENABLE;
+       if (!val)
+               goto unlock;
+
+       pd = page_address(as->pd);
+       if (!pd)
+               goto unlock;
+
+       seq_printf(s, "[SWGROUP: %s] ", swgrp->name);
+       seq_printf(s, "[as: (id: %d), ", as->id);
+       seq_printf(s, "(attr: %c|%c|%c), ",
+                  as->attr & SMMU_PD_READABLE ? 'R' : '-',
+                  as->attr & SMMU_PD_WRITABLE ? 'W' : '-',
+                  as->attr & SMMU_PD_NONSECURE ? '-' : 'S');
+       seq_printf(s, "(pd_dma: %pad)]\n", &as->pd_dma);
+       seq_puts(s, "{\n");
+
+       spin_lock_irqsave(&as->lock, flags);
+
+       for (pd_index = 0; pd_index < SMMU_NUM_PDE; pd_index++) {
+               struct page *pt_page;
+               unsigned int i;
+               u32 *addr;
+
+               /* An empty PDE should not have a pte use count */
+               WARN_ON_ONCE(!pd[pd_index] ^ !as->count[pd_index]);
+
+               /* Skip this empty PDE */
+               if (!pd[pd_index])
+                       continue;
+
+               pde_count++;
+               pte_count += as->count[pd_index];
+               seq_printf(s, "\t[index: %u] 0x%x (count: %d)\n",
+                          pd_index, pd[pd_index], as->count[pd_index]);
+               pt_page = as->pts[pd_index];
+               addr = page_address(pt_page);
+
+               seq_puts(s, "\t{\n");
+               seq_printf(s, "\t\t%-14s | %-4s | %-10s%s | %-10s%s | %-11s\n",
+                          "PTE RANGE", "ATTR",
+                          "PHYS", sizeof(phys_addr_t) > 4 ? "        " : "",
+                          "IOVA", sizeof(dma_addr_t)  > 4 ? "        " : "",
+                          "SIZE");
+               for (pt_index = 0; pt_index < SMMU_NUM_PTE; pt_index += i) {
+                       size_t size = SMMU_SIZE_PT;
+                       dma_addr_t iova;
+                       phys_addr_t pa;
+
+                       i = 1;
+
+                       if (!addr[pt_index])
+                               continue;
+
+                       iova = pd_pt_index_iova(pd_index, pt_index);
+                       pa = SMMU_PFN_PHYS(addr[pt_index] & ~SMMU_PTE_ATTR);
+
+                       /* Check contiguous mappings and increase size */
+                       while (pt_index + i < SMMU_NUM_PTE) {
+                               dma_addr_t next_iova;
+                               phys_addr_t next_pa;
+
+                               if (!addr[pt_index + i])
+                                       break;
+
+                               next_iova = pd_pt_index_iova(pd_index, pt_index 
+ i);
+                               next_pa = SMMU_PFN_PHYS(addr[pt_index + i] & 
~SMMU_PTE_ATTR);
+
+                               /* Break at the end of a linear mapping */
+                               if ((next_iova - iova != SMMU_SIZE_PT * i) ||
+                                   (next_pa - pa != SMMU_SIZE_PT * i))
+                                       break;
+
+                               i++;
+                       }
+
+                       seq_printf(s, "\t\t[#%-4u, #%-4u] | 0x%-2x | %pa | %pad 
| 0x%-9zx\n",
+                                  pt_index, pt_index + i - 1,
+                                  addr[pt_index] >> SMMU_PTE_ATTR_SHIFT,
+                                  &pa, &iova, size * i);
+               }
+               seq_puts(s, "\t}\n");
+       }
+
+       spin_unlock_irqrestore(&as->lock, flags);
+
+       seq_puts(s, "}\n");
+       seq_printf(s, "Total PDEs: %u, total PTEs: %llu\n ", pde_count, 
pte_count);
+
+unlock:
+       mutex_unlock(&smmu->lock);
+
+       return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(tegra_smmu_debugfs_mappings);
+
 static void tegra_smmu_attach_as(struct tegra_smmu *smmu,
                                 struct tegra_smmu_as *as,
                                 unsigned int swgroup)
@@ -517,6 +646,12 @@ static void tegra_smmu_attach_as(struct tegra_smmu *smmu,
                        dev_warn(smmu->dev,
                                 "overwriting group->as for swgroup: %s\n", 
swgrp->name);
                group->as = as;
+
+               if (smmu->debugfs_mappings)
+                       debugfs_create_file(group->swgrp->name, 0444,
+                                           smmu->debugfs_mappings, group,
+                                           &tegra_smmu_debugfs_mappings_fops);
+
                break;
        }
 
@@ -541,6 +676,12 @@ static void tegra_smmu_detach_as(struct tegra_smmu *smmu,
                if (group->swgrp != swgrp)
                        continue;
                group->as = NULL;
+
+               if (smmu->debugfs_mappings) {
+                       d = debugfs_lookup(group->swgrp->name, 
smmu->debugfs_mappings);
+                       debugfs_remove(d);
+               }
+
                break;
        }
 
@@ -1133,6 +1274,8 @@ static void tegra_smmu_debugfs_init(struct tegra_smmu 
*smmu)
                            &tegra_smmu_swgroups_fops);
        debugfs_create_file("clients", S_IRUGO, smmu->debugfs, smmu,
                            &tegra_smmu_clients_fops);
+
+       smmu->debugfs_mappings = debugfs_create_dir("mappings", smmu->debugfs);
 }
 
 static void tegra_smmu_debugfs_exit(struct tegra_smmu *smmu)
-- 
2.17.1

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