feat: add helper functions for SP sleep
This patch introduces new helper utilities: virtualcounter_read() and
sp_sleep_elapsed_time() which are further used in sp_sleep() utility.
This patch also adds a needed isb when reading the virtual counter,
to prevent reading stale values, as well as reducing the number of
reads of the virtual counter required. Refer Arm ARM D11.2.2
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: Icaf1777e85ee2efc043bfa83d630edf54bf5a099
diff --git a/spm/common/sp_helpers.c b/spm/common/sp_helpers.c
index a6b6bc5..77031f8 100644
--- a/spm/common/sp_helpers.c
+++ b/spm/common/sp_helpers.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2018, Arm Limited. All rights reserved.
+ * Copyright (c) 2018-2021, Arm Limited. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -58,16 +58,25 @@
INFO("Test \"%s\" end.\n", test_desc);
}
-void sp_sleep(uint32_t ms)
+uint64_t sp_sleep_elapsed_time(uint32_t ms)
{
uint64_t timer_freq = read_cntfrq_el0();
VERBOSE("%s: Timer frequency = %llu\n", __func__, timer_freq);
VERBOSE("%s: Sleeping for %u milliseconds...\n", __func__, ms);
- uint64_t time1 = read_cntvct_el0();
+
+ uint64_t time1 = virtualcounter_read();
volatile uint64_t time2 = time1;
+
while ((time2 - time1) < ((ms * timer_freq) / 1000U)) {
- time2 = read_cntvct_el0();
+ time2 = virtualcounter_read();
}
+
+ return ((time2 - time1) * 1000) / timer_freq;
+}
+
+void sp_sleep(uint32_t ms)
+{
+ (void)sp_sleep_elapsed_time(ms);
}