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

From: Sven Peter
Date: Wed Nov 17 2021 - 16:15:55 EST


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 <sven@xxxxxxxxxxxxx>
---
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