[PATCH] armv8: mmu: Extend mmu_map_region() to allow uncached mappings

[Sumit Garg]

From: Sumit Garg <sumit.garg at oss.qualcomm.com>

On Qcom platforms, cmd-db region is required to be mapped as uncached
region especially when executing at EL2. Otherwise an xPU violation
can be triggered due to cache operations as descibed by a similar fix
for the kernel here:

Commit f9bb896eab22 ("soc: qcom: cmd-db: Map shared memory as WC, not WB")

So, let's map CMD-DB region as uncached to avoid any issues while
booting U-Boot in EL2 mode.

Fixes: a9cbf76e4dd3 ("soc: qcom: cmd-db: map cmd-db region")
Signed-off-by: Sumit Garg <sumit.garg at oss.qualcomm.com>
---
 arch/arm/cpu/armv8/cache_v8.c | 11 ++++++++---
 arch/arm/include/asm/system.h |  3 ++-
 drivers/soc/qcom/cmd-db.c     |  2 +-
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/arm/cpu/armv8/cache_v8.c b/arch/arm/cpu/armv8/cache_v8.c
index 39479df7b21..05e90e1eb32 100644
--- a/arch/arm/cpu/armv8/cache_v8.c
+++ b/arch/arm/cpu/armv8/cache_v8.c
@@ -388,13 +388,18 @@ static void map_range(u64 virt, u64 phys, u64 size, int level,
 	}
 }
 
-void mmu_map_region(phys_addr_t addr, u64 size, bool emergency)
+void mmu_map_region(phys_addr_t addr, u64 size, bool cached, bool emergency)
 {
 	u64 va_bits;
 	int level = 0;
-	u64 attrs = PTE_BLOCK_MEMTYPE(MT_NORMAL) | PTE_BLOCK_INNER_SHARE;
+	u64 attrs;
 
-	attrs |= PTE_TYPE_BLOCK | PTE_BLOCK_AF;
+	if (cached)
+		attrs = PTE_BLOCK_MEMTYPE(MT_NORMAL);
+	else
+		attrs = PTE_BLOCK_MEMTYPE(MT_NORMAL_NC);
+
+	attrs |= PTE_BLOCK_INNER_SHARE | PTE_TYPE_BLOCK | PTE_BLOCK_AF;
 
 	get_tcr(NULL, &va_bits);
 	if (va_bits < 39)
diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index 5ed6833c155..52ab86112fb 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -306,9 +306,10 @@ void flush_l3_cache(void);
  *
  * @start: Start address of the region
  * @size: Size of the region
+ * @cached: Map memory as cacheable or not
  * @emerg: Also map the region in the emergency table
  */
-void mmu_map_region(phys_addr_t start, u64 size, bool emerg);
+void mmu_map_region(phys_addr_t start, u64 size, bool cached, bool emerg);
 
 /**
  * mmu_change_region_attr() - change a mapped region attributes
diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c
index d0a6047b8a6..61e15783123 100644
--- a/drivers/soc/qcom/cmd-db.c
+++ b/drivers/soc/qcom/cmd-db.c
@@ -248,7 +248,7 @@ static int cmd_db_bind(struct udevice *dev)
 	}
 
 	/* On SM8550/SM8650 and newer SoCs cmd-db might not be mapped */
-	mmu_map_region((phys_addr_t)base, (phys_size_t)size, false);
+	mmu_map_region((phys_addr_t)base, (phys_size_t)size, false, false);
 
 	cmd_db_header = base;
 	if (!cmd_db_magic_matches(cmd_db_header)) {
-- 
2.51.0