linux-kernel - [PATCH v4 4/5] iommu/io-pgtable-dart: Add DART PTE support for t6000

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Date:   Thu,  1 Sep 2022 03:25:18 +0200
From:   Janne Grunau <j@...nau.net>
To:     iommu@...ts.linux.dev
Cc:     Konrad Dybcio <konrad.dybcio@...ainline.org>,
        asahi@...ts.linux.dev, Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Hector Martin <marcan@...can.st>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 4/5] iommu/io-pgtable-dart: Add DART PTE support for t6000

From: Sven Peter <sven@...npeter.dev>

The DARTs present in the M1 Pro/Max/Ultra SoC use a diffent PTE format.
They support a 42bit physical address space by shifting the paddr and
extending its mask inside the PTE.
They also come with mandatory sub-page protection now which we just
configure to always allow access to the entire page. This feature is
already present but optional on the previous DARTs which allows to
unconditionally configure it.

Signed-off-by: Sven Peter <sven@...npeter.dev>
Co-developed-by: Janne Grunau <j@...nau.net>
Signed-off-by: Janne Grunau <j@...nau.net>

---

(no changes since v3)

Changes in v3:
- apply change to io-pgtable-dart.c
- handle pte <> paddr conversion based on the pte format instead of
  the output address size

Changes in v2:
- add APPLE_DART2 PTE format

 drivers/iommu/io-pgtable-dart.c | 49 ++++++++++++++++++++++++++++-----
 drivers/iommu/io-pgtable.c      |  1 +
 include/linux/io-pgtable.h      |  1 +
 3 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/io-pgtable-dart.c b/drivers/iommu/io-pgtable-dart.c
index 659dd9e83d2c..e91d2c654d7c 100644
--- a/drivers/iommu/io-pgtable-dart.c
+++ b/drivers/iommu/io-pgtable-dart.c
@@ -45,12 +45,19 @@
 #define APPLE_DART_PTE_SUBPAGE_END     GENMASK_ULL(51, 40)
 
 #define APPLE_DART1_PADDR_MASK	GENMASK_ULL(35, 12)
+#define APPLE_DART2_PADDR_MASK	GENMASK_ULL(37, 10)
+#define APPLE_DART2_PADDR_SHIFT	(4)
 
 /* Apple DART1 protection bits */
 #define APPLE_DART1_PTE_PROT_NO_READ	BIT(8)
 #define APPLE_DART1_PTE_PROT_NO_WRITE	BIT(7)
 #define APPLE_DART1_PTE_PROT_SP_DIS	BIT(1)
 
+/* Apple DART2 protection bits */
+#define APPLE_DART2_PTE_PROT_NO_READ	BIT(3)
+#define APPLE_DART2_PTE_PROT_NO_WRITE	BIT(2)
+#define APPLE_DART2_PTE_PROT_NO_CACHE	BIT(1)
+
 /* marks PTE as valid */
 #define APPLE_DART_PTE_VALID		BIT(0)
 
@@ -72,13 +79,31 @@ typedef u64 dart_iopte;
 static dart_iopte paddr_to_iopte(phys_addr_t paddr,
 				     struct dart_io_pgtable *data)
 {
-	return paddr & APPLE_DART1_PADDR_MASK;
+	dart_iopte pte;
+
+	if (data->iop.fmt == APPLE_DART)
+		return paddr & APPLE_DART1_PADDR_MASK;
+
+	/* format is APPLE_DART2 */
+	pte = paddr >> APPLE_DART2_PADDR_SHIFT;
+	pte &= APPLE_DART2_PADDR_MASK;
+
+	return pte;
 }
 
 static phys_addr_t iopte_to_paddr(dart_iopte pte,
 				  struct dart_io_pgtable *data)
 {
-	return pte & APPLE_DART1_PADDR_MASK;
+	u64 paddr;
+
+	if (data->iop.fmt == APPLE_DART)
+		return pte & APPLE_DART1_PADDR_MASK;
+
+	/* format is APPLE_DART2 */
+	paddr = pte & APPLE_DART2_PADDR_MASK;
+	paddr <<= APPLE_DART2_PADDR_SHIFT;
+
+	return paddr;
 }
 
 static void *__dart_alloc_pages(size_t size, gfp_t gfp,
@@ -192,10 +217,20 @@ static dart_iopte dart_prot_to_pte(struct dart_io_pgtable *data,
 {
 	dart_iopte pte = 0;
 
-	if (!(prot & IOMMU_WRITE))
-		pte |= APPLE_DART1_PTE_PROT_NO_WRITE;
-	if (!(prot & IOMMU_READ))
-		pte |= APPLE_DART1_PTE_PROT_NO_READ;
+	if (data->iop.fmt == APPLE_DART) {
+		if (!(prot & IOMMU_WRITE))
+			pte |= APPLE_DART1_PTE_PROT_NO_WRITE;
+		if (!(prot & IOMMU_READ))
+			pte |= APPLE_DART1_PTE_PROT_NO_READ;
+	}
+	if (data->iop.fmt == APPLE_DART2) {
+		if (!(prot & IOMMU_WRITE))
+			pte |= APPLE_DART2_PTE_PROT_NO_WRITE;
+		if (!(prot & IOMMU_READ))
+			pte |= APPLE_DART2_PTE_PROT_NO_READ;
+		if (!(prot & IOMMU_CACHE))
+			pte |= APPLE_DART2_PTE_PROT_NO_CACHE;
+	}
 
 	return pte;
 }
@@ -370,7 +405,7 @@ apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
 	if (!cfg->coherent_walk)
 		return NULL;
 
-	if (cfg->oas > DART1_MAX_ADDR_BITS)
+	if (cfg->oas != 36 && cfg->oas != 42)
 		return NULL;
 
 	if (cfg->ias > cfg->oas)
diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c
index 16205ea9272c..49f46e1eabf7 100644
--- a/drivers/iommu/io-pgtable.c
+++ b/drivers/iommu/io-pgtable.c
@@ -23,6 +23,7 @@ io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {
 #endif
 #ifdef CONFIG_IOMMU_IO_PGTABLE_DART
 	[APPLE_DART] = &io_pgtable_apple_dart_init_fns,
+	[APPLE_DART2] = &io_pgtable_apple_dart_init_fns,
 #endif
 #ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S
 	[ARM_V7S] = &io_pgtable_arm_v7s_init_fns,
diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index 86af6f0a00a2..76b98511cbc8 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -17,6 +17,7 @@ enum io_pgtable_fmt {
 	ARM_MALI_LPAE,
 	AMD_IOMMU_V1,
 	APPLE_DART,
+	APPLE_DART2,
 	IO_PGTABLE_NUM_FMTS,
 };
 
-- 
2.35.1