ARM: at91: setup outer cache .write_sec() callback if needed

When running under OP-TEE, the L2 cache is configured by OP-TEE and the
sam platform code does not allow any modification yet. Setup a dummy
.write_sec() callback to avoid triggering exceptions when Linux tries
to modify the L2 cache configuration.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
[claudiu.beznea: keep .init_early populated only for SAMA5D2, remove
 sam_secure_init() from sama5d2_init() as it is also called in
 sama5_secure_cache_init()]
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220606145701.185552-3-clement.leger@bootlin.com

arch/arm/mach-at91/sama5.c

@@ -9,13 +9,27 @@
 #include <linux/of.h>
 #include <linux/of_platform.h>
 
+#include <asm/hardware/cache-l2x0.h>
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
+#include <asm/outercache.h>
 #include <asm/system_misc.h>
 
 #include "generic.h"
 #include "sam_secure.h"
 
+static void sama5_l2c310_write_sec(unsigned long val, unsigned reg)
+{
+	/* OP-TEE configures the L2 cache and does not allow modifying it yet */
+}
+
+static void __init sama5_secure_cache_init(void)
+{
+	sam_secure_init();
+	if (sam_linux_is_optee_available())
+		outer_cache.write_sec = sama5_l2c310_write_sec;
+}
+
 static void __init sama5_dt_device_init(void)
 {
 	of_platform_default_populate(NULL, NULL, NULL);
@@ -48,7 +62,6 @@ MACHINE_END
 static void __init sama5d2_init(void)
 {
 	of_platform_default_populate(NULL, NULL, NULL);
-	sam_secure_init();
 	sama5d2_pm_init();
 }
 
@@ -60,6 +73,7 @@ static const char *const sama5d2_compat[] __initconst = {
 DT_MACHINE_START(sama5d2, "Atmel SAMA5")
 	/* Maintainer: Atmel */
 	.init_machine	= sama5d2_init,
+	.init_early	= sama5_secure_cache_init,
 	.dt_compat	= sama5d2_compat,
 	.l2c_aux_mask	= ~0UL,
 MACHINE_END