drm/panthor: Make MMU cache maintenance use FLUSH_CACHES command

As the FLUSH_MEM and FLUSH_PT MMU_AS commands are deprecated in GPUs
from Mali-Gx20 onwards, this patch adds support for performing cache
maintenance via the FLUSH_CACHES command in GPU_COMMAND in place of
FLUSH_MEM and FLUSH_PT commands.

Mali-Gx10 and Mali-Gx15 GPUs also has support for the FLUSH_CACHES
command and will also use this by default going forward.

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Karunika Choo <karunika.choo@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20250807162633.3666310-7-karunika.choo@arm.com

Author: Karunika Choo

drivers/gpu/drm/panthor/panthor_mmu.c

@@ -29,6 +29,7 @@
 
 #include "panthor_device.h"
 #include "panthor_gem.h"
+#include "panthor_gpu.h"
 #include "panthor_heap.h"
 #include "panthor_mmu.h"
 #include "panthor_regs.h"
@@ -568,6 +569,35 @@ static void lock_region(struct panthor_device *ptdev, u32 as_nr,
 	write_cmd(ptdev, as_nr, AS_COMMAND_LOCK);
 }
 
+static int mmu_hw_do_flush_on_gpu_ctrl(struct panthor_device *ptdev, int as_nr,
+				       u32 op)
+{
+	const u32 l2_flush_op = CACHE_CLEAN | CACHE_INV;
+	u32 lsc_flush_op = 0;
+	int ret;
+
+	if (op == AS_COMMAND_FLUSH_MEM)
+		lsc_flush_op = CACHE_CLEAN | CACHE_INV;
+
+	ret = wait_ready(ptdev, as_nr);
+	if (ret)
+		return ret;
+
+	ret = panthor_gpu_flush_caches(ptdev, l2_flush_op, lsc_flush_op, 0);
+	if (ret)
+		return ret;
+
+	/*
+	 * Explicitly unlock the region as the AS is not unlocked automatically
+	 * at the end of the GPU_CONTROL cache flush command, unlike
+	 * AS_COMMAND_FLUSH_MEM or AS_COMMAND_FLUSH_PT.
+	 */
+	write_cmd(ptdev, as_nr, AS_COMMAND_UNLOCK);
+
+	/* Wait for the unlock command to complete */
+	return wait_ready(ptdev, as_nr);
+}
+
 static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
 				      u64 iova, u64 size, u32 op)
 {
@@ -585,6 +615,9 @@ static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
 	if (op != AS_COMMAND_UNLOCK)
 		lock_region(ptdev, as_nr, iova, size);
 
+	if (op == AS_COMMAND_FLUSH_MEM || op == AS_COMMAND_FLUSH_PT)
+		return mmu_hw_do_flush_on_gpu_ctrl(ptdev, as_nr, op);
+
 	/* Run the MMU operation */
 	write_cmd(ptdev, as_nr, op);