iommu/io-pgtable-arm: Add support to use system cache

Add a quirk IO_PGTABLE_QUIRK_ARM_OUTER_WBWA to override
the outer-cacheability attributes set in the TCR for a
non-coherent page table walker when using system cache.

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Link: https://lore.kernel.org/r/f818676b4a2a9ad1edb92721947d47db41ed6a7c.1606287059.git.saiprakash.ranjan@codeaurora.org
Signed-off-by: Will Deacon <will@kernel.org>

drivers/iommu/io-pgtable-arm.c

@@ -761,7 +761,8 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
 
 	if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS |
 			    IO_PGTABLE_QUIRK_NON_STRICT |
-			    IO_PGTABLE_QUIRK_ARM_TTBR1))
+			    IO_PGTABLE_QUIRK_ARM_TTBR1 |
+			    IO_PGTABLE_QUIRK_ARM_OUTER_WBWA))
 		return NULL;
 
 	data = arm_lpae_alloc_pgtable(cfg);
@@ -773,10 +774,15 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
 		tcr->sh = ARM_LPAE_TCR_SH_IS;
 		tcr->irgn = ARM_LPAE_TCR_RGN_WBWA;
 		tcr->orgn = ARM_LPAE_TCR_RGN_WBWA;
+		if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_OUTER_WBWA)
+			goto out_free_data;
 	} else {
 		tcr->sh = ARM_LPAE_TCR_SH_OS;
 		tcr->irgn = ARM_LPAE_TCR_RGN_NC;
-		tcr->orgn = ARM_LPAE_TCR_RGN_NC;
+		if (!(cfg->quirks & IO_PGTABLE_QUIRK_ARM_OUTER_WBWA))
+			tcr->orgn = ARM_LPAE_TCR_RGN_NC;
+		else
+			tcr->orgn = ARM_LPAE_TCR_RGN_WBWA;
 	}
 
 	tg1 = cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1;

include/linux/io-pgtable.h

@@ -86,6 +86,9 @@ struct io_pgtable_cfg {
 	 *
 	 * IO_PGTABLE_QUIRK_ARM_TTBR1: (ARM LPAE format) Configure the table
 	 *	for use in the upper half of a split address space.
+	 *
+	 * IO_PGTABLE_QUIRK_ARM_OUTER_WBWA: Override the outer-cacheability
+	 *	attributes set in the TCR for a non-coherent page-table walker.
 	 */
 	#define IO_PGTABLE_QUIRK_ARM_NS		BIT(0)
 	#define IO_PGTABLE_QUIRK_NO_PERMS	BIT(1)
@@ -93,6 +96,7 @@ struct io_pgtable_cfg {
 	#define IO_PGTABLE_QUIRK_ARM_MTK_EXT	BIT(3)
 	#define IO_PGTABLE_QUIRK_NON_STRICT	BIT(4)
 	#define IO_PGTABLE_QUIRK_ARM_TTBR1	BIT(5)
+	#define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA	BIT(6)
 	unsigned long			quirks;
 	unsigned long			pgsize_bitmap;
 	unsigned int			ias;