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-rw-r--r--lib/psci/aarch32/psci_helpers.S148
1 files changed, 148 insertions, 0 deletions
diff --git a/lib/psci/aarch32/psci_helpers.S b/lib/psci/aarch32/psci_helpers.S
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+/*
+ * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <asm_macros.S>
+#include <lib/psci/psci.h>
+#include <platform_def.h>
+
+ .globl psci_do_pwrdown_cache_maintenance
+ .globl psci_do_pwrup_cache_maintenance
+ .globl psci_power_down_wfi
+
+/* -----------------------------------------------------------------------
+ * void psci_do_pwrdown_cache_maintenance(unsigned int power level);
+ *
+ * This function performs cache maintenance for the specified power
+ * level. The levels of cache affected are determined by the power
+ * level which is passed as the argument i.e. level 0 results
+ * in a flush of the L1 cache. Both the L1 and L2 caches are flushed
+ * for a higher power level.
+ *
+ * Additionally, this function also ensures that stack memory is correctly
+ * flushed out to avoid coherency issues due to a change in its memory
+ * attributes after the data cache is disabled.
+ * -----------------------------------------------------------------------
+ */
+func psci_do_pwrdown_cache_maintenance
+ push {r4, lr}
+
+ /* ----------------------------------------------
+ * Turn OFF cache and do stack maintenance
+ * prior to cpu operations . This sequence is
+ * different from AArch64 because in AArch32 the
+ * assembler routines for cpu operations utilize
+ * the stack whereas in AArch64 it doesn't.
+ * ----------------------------------------------
+ */
+ mov r4, r0
+ bl do_stack_maintenance
+
+ /* ---------------------------------------------
+ * Invoke CPU-specifc power down operations for
+ * the appropriate level
+ * ---------------------------------------------
+ */
+ mov r0, r4
+ pop {r4, lr}
+ b prepare_cpu_pwr_dwn
+endfunc psci_do_pwrdown_cache_maintenance
+
+
+/* -----------------------------------------------------------------------
+ * void psci_do_pwrup_cache_maintenance(void);
+ *
+ * This function performs cache maintenance after this cpu is powered up.
+ * Currently, this involves managing the used stack memory before turning
+ * on the data cache.
+ * -----------------------------------------------------------------------
+ */
+func psci_do_pwrup_cache_maintenance
+ /* r12 is pushed to meet the 8 byte stack alignment requirement */
+ push {r12, lr}
+
+ /* ---------------------------------------------
+ * Ensure any inflight stack writes have made it
+ * to main memory.
+ * ---------------------------------------------
+ */
+ dmb st
+
+ /* ---------------------------------------------
+ * Calculate and store the size of the used
+ * stack memory in r1. Calculate and store the
+ * stack base address in r0.
+ * ---------------------------------------------
+ */
+ bl plat_get_my_stack
+ mov r1, sp
+ sub r1, r0, r1
+ mov r0, sp
+ bl inv_dcache_range
+
+ /* ---------------------------------------------
+ * Enable the data cache.
+ * ---------------------------------------------
+ */
+ ldcopr r0, SCTLR
+ orr r0, r0, #SCTLR_C_BIT
+ stcopr r0, SCTLR
+ isb
+
+ pop {r12, pc}
+endfunc psci_do_pwrup_cache_maintenance
+
+ /* ---------------------------------------------
+ * void do_stack_maintenance(void)
+ * Do stack maintenance by flushing the used
+ * stack to the main memory and invalidating the
+ * remainder.
+ * ---------------------------------------------
+ */
+func do_stack_maintenance
+ push {r4, lr}
+ bl plat_get_my_stack
+
+ /* Turn off the D-cache */
+ ldcopr r1, SCTLR
+ bic r1, #SCTLR_C_BIT
+ stcopr r1, SCTLR
+ isb
+
+ /* ---------------------------------------------
+ * Calculate and store the size of the used
+ * stack memory in r1.
+ * ---------------------------------------------
+ */
+ mov r4, r0
+ mov r1, sp
+ sub r1, r0, r1
+ mov r0, sp
+ bl flush_dcache_range
+
+ /* ---------------------------------------------
+ * Calculate and store the size of the unused
+ * stack memory in r1. Calculate and store the
+ * stack base address in r0.
+ * ---------------------------------------------
+ */
+ sub r0, r4, #PLATFORM_STACK_SIZE
+ sub r1, sp, r0
+ bl inv_dcache_range
+
+ pop {r4, pc}
+endfunc do_stack_maintenance
+
+/* -----------------------------------------------------------------------
+ * This function is called to indicate to the power controller that it
+ * is safe to power down this cpu. It should not exit the wfi and will
+ * be released from reset upon power up.
+ * -----------------------------------------------------------------------
+ */
+func psci_power_down_wfi
+ dsb sy // ensure write buffer empty
+ wfi
+ no_ret plat_panic_handler
+endfunc psci_power_down_wfi