ti: k3: common: Do not disable cache on TI K3 core powerdown

Leave the caches on and explicitly flush any data that
may be stale when the core is powered down. This prevents
non-coherent interconnect access which has negative side-
effects on AM65x.
Signed-off-by: Andrew F. Davis <afd@ti.com>

lib/cpus/aarch64/cortex_a53.S

@@ -228,11 +228,13 @@ endfunc cortex_a53_reset_func
 func cortex_a53_core_pwr_dwn
 	mov	x18, x30
 
+#if !TI_AM65X_WORKAROUND
 	/* ---------------------------------------------
 	 * Turn off caches.
 	 * ---------------------------------------------
 	 */
 	bl	cortex_a53_disable_dcache
+#endif
 
 	/* ---------------------------------------------
 	 * Flush L1 caches.
@@ -252,11 +254,13 @@ endfunc cortex_a53_core_pwr_dwn
 func cortex_a53_cluster_pwr_dwn
 	mov	x18, x30
 
+#if !TI_AM65X_WORKAROUND
 	/* ---------------------------------------------
 	 * Turn off caches.
 	 * ---------------------------------------------
 	 */
 	bl	cortex_a53_disable_dcache
+#endif
 
 	/* ---------------------------------------------
 	 * Flush L1 caches.

plat/ti/k3/common/k3_psci.c

@@ -6,9 +6,12 @@
 
 #include <arch_helpers.h>
 #include <assert.h>
+#include <cpu_data.h>
 #include <debug.h>
 #include <k3_gicv3.h>
 #include <psci.h>
+/* Need to flush psci internal locks before shutdown or their values are lost */
+#include <../../lib/psci/psci_private.h>
 #include <platform.h>
 #include <stdbool.h>
 
@@ -99,6 +102,14 @@ void k3_pwr_domain_on_finish(const psci_power_state_t *target_state)
 	k3_gic_cpuif_enable();
 }
 
+static void  __dead2 k3_pwr_domain_pwr_down_wfi(const psci_power_state_t
+						  *target_state)
+{
+	flush_cpu_data(psci_svc_cpu_data);
+	flush_dcache_range((uintptr_t) psci_locks, sizeof(psci_locks));
+	psci_power_down_wfi();
+}
+
 static void __dead2 k3_system_reset(void)
 {
 	/* Send the system reset request to system firmware */
@@ -128,6 +139,7 @@ static const plat_psci_ops_t k3_plat_psci_ops = {
 	.pwr_domain_on = k3_pwr_domain_on,
 	.pwr_domain_off = k3_pwr_domain_off,
 	.pwr_domain_on_finish = k3_pwr_domain_on_finish,
+	.pwr_domain_pwr_down_wfi = k3_pwr_domain_pwr_down_wfi,
 	.system_reset = k3_system_reset,
 	.validate_power_state = k3_validate_power_state,
 	.validate_ns_entrypoint = k3_validate_ns_entrypoint

plat/ti/k3/common/plat_common.mk

@@ -12,7 +12,7 @@ COLD_BOOT_SINGLE_CPU	:=	1
 PROGRAMMABLE_RESET_ADDRESS:=	1
 
 # System coherency is managed in hardware
-WARMBOOT_ENABLE_DCACHE_EARLY:=	1
+HW_ASSISTED_COHERENCY	:=	1
 USE_COHERENT_MEM	:=	0
 
 # A53 erratum for SoC. (enable them all)
@@ -22,6 +22,10 @@ ERRATA_A53_836870	:=	1
 ERRATA_A53_843419	:=	1
 ERRATA_A53_855873	:=	1
 
+# Leave the caches enabled on core powerdown path
+TI_AM65X_WORKAROUND	:=	1
+$(eval $(call add_define,TI_AM65X_WORKAROUND))
+
 MULTI_CONSOLE_API	:=	1
 TI_16550_MDR_QUIRK	:=	1
 $(eval $(call add_define,TI_16550_MDR_QUIRK))