iommu/io-pgtable: Add DART pagetable format

Apple's DART iommu uses a pagetable format that shares some
similarities with the ones already implemented by io-pgtable.c.
Add a new format variant to support the required differences
so that we don't have to duplicate the pagetable handling code.

Reviewed-by: Alexander Graf <[e-mail]>
Reviewed-by: Alyssa Rosenzweig <[e-mail]>
Reviewed-by: Robin Murphy <[e-mail]>
Signed-off-by: Sven Peter <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Joerg Roedel <[e-mail]>

drivers/iommu/io-pgtable-arm.c

···
 #define ARM_MALI_LPAE_MEMATTR_IMP_DEF	0x88ULL
 #define ARM_MALI_LPAE_MEMATTR_WRITE_ALLOC 0x8DULL
 
+#define APPLE_DART_PTE_PROT_NO_WRITE (1<<7)
+#define APPLE_DART_PTE_PROT_NO_READ (1<<8)
+
 /* IOPTE accessors */
 #define iopte_deref(pte,d) __va(iopte_to_paddr(pte, d))
 
···
 					   int prot)
 {
 	arm_lpae_iopte pte;
+
+	if (data->iop.fmt == APPLE_DART) {
+		pte = 0;
+		if (!(prot & IOMMU_WRITE))
+			pte |= APPLE_DART_PTE_PROT_NO_WRITE;
+		if (!(prot & IOMMU_READ))
+			pte |= APPLE_DART_PTE_PROT_NO_READ;
+		return pte;
+	}
 
 	if (data->iop.fmt == ARM_64_LPAE_S1 ||
 	    data->iop.fmt == ARM_32_LPAE_S1) {
···
 	return NULL;
 }
 
+static struct io_pgtable *
+apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
+{
+	struct arm_lpae_io_pgtable *data;
+	int i;
+
+	if (cfg->oas > 36)
+		return NULL;
+
+	data = arm_lpae_alloc_pgtable(cfg);
+	if (!data)
+		return NULL;
+
+	/*
+	 * The table format itself always uses two levels, but the total VA
+	 * space is mapped by four separate tables, making the MMIO registers
+	 * an effective "level 1". For simplicity, though, we treat this
+	 * equivalently to LPAE stage 2 concatenation at level 2, with the
+	 * additional TTBRs each just pointing at consecutive pages.
+	 */
+	if (data->start_level < 1)
+		goto out_free_data;
+	if (data->start_level == 1 && data->pgd_bits > 2)
+		goto out_free_data;
+	if (data->start_level > 1)
+		data->pgd_bits = 0;
+	data->start_level = 2;
+	cfg->apple_dart_cfg.n_ttbrs = 1 << data->pgd_bits;
+	data->pgd_bits += data->bits_per_level;
+
+	data->pgd = __arm_lpae_alloc_pages(ARM_LPAE_PGD_SIZE(data), GFP_KERNEL,
+					   cfg);
+	if (!data->pgd)
+		goto out_free_data;
+
+	for (i = 0; i < cfg->apple_dart_cfg.n_ttbrs; ++i)
+		cfg->apple_dart_cfg.ttbr[i] =
+			virt_to_phys(data->pgd + i * ARM_LPAE_GRANULE(data));
+
+	return &data->iop;
+
+out_free_data:
+	kfree(data);
+	return NULL;
+}
+
 struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns = {
 	.alloc	= arm_64_lpae_alloc_pgtable_s1,
 	.free	= arm_lpae_free_pgtable,
···
 
 struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns = {
 	.alloc	= arm_mali_lpae_alloc_pgtable,
+	.free	= arm_lpae_free_pgtable,
+};
+
+struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns = {
+	.alloc	= apple_dart_alloc_pgtable,
 	.free	= arm_lpae_free_pgtable,
 };
 

drivers/iommu/io-pgtable.c

···
 	[ARM_64_LPAE_S1] = &io_pgtable_arm_64_lpae_s1_init_fns,
 	[ARM_64_LPAE_S2] = &io_pgtable_arm_64_lpae_s2_init_fns,
 	[ARM_MALI_LPAE] = &io_pgtable_arm_mali_lpae_init_fns,
+	[APPLE_DART] = &io_pgtable_apple_dart_init_fns,
 #endif
 #ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S
 	[ARM_V7S] = &io_pgtable_arm_v7s_init_fns,

include/linux/io-pgtable.h

···
 	ARM_V7S,
 	ARM_MALI_LPAE,
 	AMD_IOMMU_V1,
+	APPLE_DART,
 	IO_PGTABLE_NUM_FMTS,
 };
 
···
 			u64	transtab;
 			u64	memattr;
 		} arm_mali_lpae_cfg;
+
+		struct {
+			u64 ttbr[4];
+			u32 n_ttbrs;
+		} apple_dart_cfg;
 	};
 };
 
···
 extern struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_amd_iommu_v1_init_fns;
+extern struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns;
 
 #endif /* __IO_PGTABLE_H */