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 <graf@amazon.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Link: https://lore.kernel.org/r/20210803121651.61594-2-sven@svenpeter.dev
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 63 insertions, 0 deletions

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 053df4048a29..0779eb96bd29 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -130,6 +130,9 @@
 #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))
 
@@ -402,6 +405,15 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
 {
 	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) {
 		pte = ARM_LPAE_PTE_nG;
@@ -1102,6 +1114,52 @@ out_free_data:
 	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,
@@ -1127,6 +1185,11 @@ struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns = {
 	.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,
+};
+
 #ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE_SELFTEST
 
 static struct io_pgtable_cfg *cfg_cookie __initdata;