[PATCH 3/4] iommu/io-pgtable: Add DART PTE support for t6000

[Sven Peter via iommu]

The DARTs present in the M1 Pro/Max SoC support a 42bit physical address
space by shifting the paddr and extending its mask inside the PTE.

Signed-off-by: Sven Peter <s...@svenpeter.dev>
---
 drivers/iommu/io-pgtable-arm.c | 30 +++++++++++++++++++++++++++++-
 include/linux/io-pgtable.h     |  2 ++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index a8c660b8b3e9..be66774aaf70 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -137,6 +137,11 @@
 #define APPLE_DART_PTE_SUBPAGE_START   GENMASK_ULL(63, 52)
 #define APPLE_DART_PTE_SUBPAGE_END     GENMASK_ULL(51, 40)
 
+#define APPLE_DART_PADDR_MASK_PS_36BIT GENMASK_ULL(35, 12)
+#define APPLE_DART_PADDR_SHIFT_PS_36BIT        (0)
+#define APPLE_DART_PADDR_MASK_PS_42BIT GENMASK_ULL(37, 10)
+#define APPLE_DART_PADDR_SHIFT_PS_42BIT        (4)
+
 /* IOPTE accessors */
 #define iopte_deref(pte,d) __va(iopte_to_paddr(pte, d))
 
@@ -171,6 +176,13 @@ static arm_lpae_iopte paddr_to_iopte(phys_addr_t paddr,
 {
        arm_lpae_iopte pte = paddr;
 
+       if (data->iop.fmt == APPLE_DART) {
+               pte = paddr >> data->iop.cfg.apple_dart_cfg.paddr_shift;
+               pte &= data->iop.cfg.apple_dart_cfg.paddr_mask;
+
+               return pte;
+       }
+
        /* Of the bits which overlap, either 51:48 or 15:12 are always RES0 */
        return (pte | (pte >> (48 - 12))) & ARM_LPAE_PTE_ADDR_MASK;
 }
@@ -180,6 +192,12 @@ static phys_addr_t iopte_to_paddr(arm_lpae_iopte pte,
 {
        u64 paddr = pte & ARM_LPAE_PTE_ADDR_MASK;
 
+       if (data->iop.fmt == APPLE_DART) {
+               paddr = pte & data->iop.cfg.apple_dart_cfg.paddr_mask;
+               paddr <<= data->iop.cfg.apple_dart_cfg.paddr_shift;
+               return paddr;
+       }
+
        if (ARM_LPAE_GRANULE(data) < SZ_64K)
                return paddr;
 
@@ -1122,8 +1140,18 @@ apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, 
void *cookie)
        struct arm_lpae_io_pgtable *data;
        int i;
 
-       if (cfg->oas > 36)
+       switch (cfg->oas) {
+       case 36:
+               cfg->apple_dart_cfg.paddr_shift = 
APPLE_DART_PADDR_SHIFT_PS_36BIT;
+               cfg->apple_dart_cfg.paddr_mask = APPLE_DART_PADDR_MASK_PS_36BIT;
+               break;
+       case 42:
+               cfg->apple_dart_cfg.paddr_shift = 
APPLE_DART_PADDR_SHIFT_PS_42BIT;
+               cfg->apple_dart_cfg.paddr_mask = APPLE_DART_PADDR_MASK_PS_42BIT;
+               break;
+       default:
                return NULL;
+       }
 
        data = arm_lpae_alloc_pgtable(cfg);
        if (!data)
diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index 86af6f0a00a2..4e26ebb0be93 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -136,6 +136,8 @@ struct io_pgtable_cfg {
                struct {
                        u64 ttbr[4];
                        u32 n_ttbrs;
+                       u32 paddr_shift;
+                       u64 paddr_mask;
                } apple_dart_cfg;
        };
 };
-- 
2.25.1

_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu