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authorAngelos Mouzakitis <a.mouzakitis@virtualopensystems.com>2023-10-10 14:33:42 +0000
committerAngelos Mouzakitis <a.mouzakitis@virtualopensystems.com>2023-10-10 14:33:42 +0000
commitaf1a266670d040d2f4083ff309d732d648afba2a (patch)
tree2fc46203448ddcc6f81546d379abfaeb323575e9 /roms/u-boot/arch/arm/cpu/armv8/generic_timer.c
parente02cda008591317b1625707ff8e115a4841aa889 (diff)
Add submodule dependency filesHEADmaster
Change-Id: Iaf8d18082d3991dec7c0ebbea540f092188eb4ec
Diffstat (limited to 'roms/u-boot/arch/arm/cpu/armv8/generic_timer.c')
-rw-r--r--roms/u-boot/arch/arm/cpu/armv8/generic_timer.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/roms/u-boot/arch/arm/cpu/armv8/generic_timer.c b/roms/u-boot/arch/arm/cpu/armv8/generic_timer.c
new file mode 100644
index 000000000..f27a74b9d
--- /dev/null
+++ b/roms/u-boot/arch/arm/cpu/armv8/generic_timer.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2013
+ * David Feng <fenghua@phytium.com.cn>
+ */
+
+#include <common.h>
+#include <bootstage.h>
+#include <command.h>
+#include <time.h>
+#include <asm/global_data.h>
+#include <asm/system.h>
+#include <linux/bitops.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * Generic timer implementation of get_tbclk()
+ */
+unsigned long get_tbclk(void)
+{
+ unsigned long cntfrq;
+ asm volatile("mrs %0, cntfrq_el0" : "=r" (cntfrq));
+ return cntfrq;
+}
+
+#ifdef CONFIG_SYS_FSL_ERRATUM_A008585
+/*
+ * FSL erratum A-008585 says that the ARM generic timer counter "has the
+ * potential to contain an erroneous value for a small number of core
+ * clock cycles every time the timer value changes".
+ * This sometimes leads to a consecutive counter read returning a lower
+ * value than the previous one, thus reporting the time to go backwards.
+ * The workaround is to read the counter twice and only return when the value
+ * was the same in both reads.
+ * Assumes that the CPU runs in much higher frequency than the timer.
+ */
+unsigned long timer_read_counter(void)
+{
+ unsigned long cntpct;
+ unsigned long temp;
+
+ isb();
+ asm volatile("mrs %0, cntpct_el0" : "=r" (cntpct));
+ asm volatile("mrs %0, cntpct_el0" : "=r" (temp));
+ while (temp != cntpct) {
+ asm volatile("mrs %0, cntpct_el0" : "=r" (cntpct));
+ asm volatile("mrs %0, cntpct_el0" : "=r" (temp));
+ }
+
+ return cntpct;
+}
+#elif CONFIG_SUNXI_A64_TIMER_ERRATUM
+/*
+ * This erratum sometimes flips the lower 11 bits of the counter value
+ * to all 0's or all 1's, leading to jumps forwards or backwards.
+ * Backwards jumps might be interpreted all roll-overs and be treated as
+ * huge jumps forward.
+ * The workaround is to check whether the lower 11 bits of the counter are
+ * all 0 or all 1, then discard this value and read again.
+ * This occasionally discards valid values, but will catch all erroneous
+ * reads and fixes the problem reliably. Also this mostly requires only a
+ * single read, so does not have any significant overhead.
+ * The algorithm was conceived by Samuel Holland.
+ */
+unsigned long timer_read_counter(void)
+{
+ unsigned long cntpct;
+
+ isb();
+ do {
+ asm volatile("mrs %0, cntpct_el0" : "=r" (cntpct));
+ } while (((cntpct + 1) & GENMASK(10, 0)) <= 1);
+
+ return cntpct;
+}
+#else
+/*
+ * timer_read_counter() using the Arm Generic Timer (aka arch timer).
+ */
+unsigned long timer_read_counter(void)
+{
+ unsigned long cntpct;
+
+ isb();
+ asm volatile("mrs %0, cntpct_el0" : "=r" (cntpct));
+
+ return cntpct;
+}
+#endif
+
+uint64_t get_ticks(void)
+{
+ unsigned long ticks = timer_read_counter();
+
+ gd->arch.tbl = ticks;
+
+ return ticks;
+}
+
+unsigned long usec2ticks(unsigned long usec)
+{
+ ulong ticks;
+ if (usec < 1000)
+ ticks = ((usec * (get_tbclk()/1000)) + 500) / 1000;
+ else
+ ticks = ((usec / 10) * (get_tbclk() / 100000));
+
+ return ticks;
+}
+
+ulong timer_get_boot_us(void)
+{
+ u64 val = get_ticks() * 1000000;
+
+ return val / get_tbclk();
+}