diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 1f09d043d086..ddb8ce5333ba 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -44,6 +44,8 @@ stable kernels.
 
 | Implementor    | Component       | Erratum ID      | Kconfig                     |
 +----------------+-----------------+-----------------+-----------------------------+
+| Allwinner      | A64/R18         | UNKNOWN1        | SUN50I_ERRATUM_UNKNOWN1     |
+|                |                 |                 |                             |
 | ARM            | Cortex-A53      | #826319         | ARM64_ERRATUM_826319        |
 | ARM            | Cortex-A53      | #827319         | ARM64_ERRATUM_827319        |
 | ARM            | Cortex-A53      | #824069         | ARM64_ERRATUM_824069        |
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index a9e26f6a81a1..8dfd3bc448d0 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -360,6 +360,16 @@ config ARM64_ERRATUM_858921
 	  The workaround will be dynamically enabled when an affected
 	  core is detected.
 
+config SUN50I_ERRATUM_UNKNOWN1
+	bool "Workaround for Allwinner A64 erratum UNKNOWN1"
+	default y
+	depends on ARM_ARCH_TIMER && ARM64 && ARCH_SUNXI
+	select ARM_ARCH_TIMER_OOL_WORKAROUND
+	help
+	  This option enables a workaround for instability in the timer on
+	  the Allwinner A64 SoC. The workaround will only be active if the
+	  allwinner,erratum-unknown1 property is found in the timer node.
+
 config ARM_GLOBAL_TIMER
 	bool "Support for the ARM global timer" if COMPILE_TEST
 	select TIMER_OF if OF
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 9a7d4dc00b6e..a8b20b65bd4b 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -326,6 +326,48 @@ static u64 notrace arm64_1188873_read_cntvct_el0(void)
 }
 #endif
 
+#ifdef CONFIG_SUN50I_ERRATUM_UNKNOWN1
+/*
+ * The low bits of the counter registers are indeterminate while bit 10 or
+ * greater is rolling over. Since the counter value can jump both backward
+ * (7ff -> 000 -> 800) and forward (7ff -> fff -> 800), ignore register values
+ * with all ones or all zeros in the low bits. Bound the loop by the maximum
+ * number of CPU cycles in 3 consecutive 24 MHz counter periods.
+ */
+#define __sun50i_a64_read_reg(reg) ({					\
+	u64 _val;							\
+	int _retries = 150;						\
+									\
+	do {								\
+		_val = read_sysreg(reg);				\
+		_retries--;						\
+	} while (((_val + 1) & GENMASK(9, 0)) <= 1 && _retries);	\
+									\
+	WARN_ON_ONCE(!_retries);					\
+	_val;								\
+})
+
+static u64 notrace sun50i_a64_read_cntpct_el0(void)
+{
+	return __sun50i_a64_read_reg(cntpct_el0);
+}
+
+static u64 notrace sun50i_a64_read_cntvct_el0(void)
+{
+	return __sun50i_a64_read_reg(cntvct_el0);
+}
+
+static u32 notrace sun50i_a64_read_cntp_tval_el0(void)
+{
+	return read_sysreg(cntp_cval_el0) - sun50i_a64_read_cntpct_el0();
+}
+
+static u32 notrace sun50i_a64_read_cntv_tval_el0(void)
+{
+	return read_sysreg(cntv_cval_el0) - sun50i_a64_read_cntvct_el0();
+}
+#endif
+
 #ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND
 DEFINE_PER_CPU(const struct arch_timer_erratum_workaround *, timer_unstable_counter_workaround);
 EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround);
@@ -423,6 +465,19 @@ static const struct arch_timer_erratum_workaround ool_workarounds[] = {
 		.read_cntvct_el0 = arm64_1188873_read_cntvct_el0,
 	},
 #endif
+#ifdef CONFIG_SUN50I_ERRATUM_UNKNOWN1
+	{
+		.match_type = ate_match_dt,
+		.id = "allwinner,erratum-unknown1",
+		.desc = "Allwinner erratum UNKNOWN1",
+		.read_cntp_tval_el0 = sun50i_a64_read_cntp_tval_el0,
+		.read_cntv_tval_el0 = sun50i_a64_read_cntv_tval_el0,
+		.read_cntpct_el0 = sun50i_a64_read_cntpct_el0,
+		.read_cntvct_el0 = sun50i_a64_read_cntvct_el0,
+		.set_next_event_phys = erratum_set_next_event_tval_phys,
+		.set_next_event_virt = erratum_set_next_event_tval_virt,
+	},
+#endif
 };
 
 typedef bool (*ate_match_fn_t)(const struct arch_timer_erratum_workaround *,