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Subject[PATCH v2 08/18] arm64: arch_timer: Add erratum handler for CPU-specific capability
Date
Should we ever have a workaround for an erratum that is detected using
a capability and affecting a particular CPU, it'd be nice to have
a way to probe them directly.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/include/asm/arch_timer.h | 1 +
drivers/clocksource/arm_arch_timer.c | 28 ++++++++++++++++++++++++----
2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index 48bd730d568f..e5325299aa6d 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -40,6 +40,7 @@ extern struct static_key_false arch_timer_read_ool_enabled;
enum arch_timer_erratum_match_type {
ate_match_dt,
ate_match_global_cap_id,
+ ate_match_local_cap_id,
};

struct arch_timer_erratum_workaround {
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index a0b1108a4a24..5069cb3d4326 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -221,6 +221,13 @@ bool arch_timer_check_global_cap_erratum(const struct arch_timer_erratum_workaro
return cpus_have_cap((uintptr_t)wa->id);
}

+static
+bool arch_timer_check_local_cap_erratum(const struct arch_timer_erratum_workaround *wa,
+ const void *arg)
+{
+ return this_cpu_has_cap((uintptr_t)wa->id);
+}
+
static const struct arch_timer_erratum_workaround *
arch_timer_iterate_errata(enum arch_timer_erratum_match_type type,
ate_match_fn_t match_fn,
@@ -251,9 +258,7 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t
{
const struct arch_timer_erratum_workaround *wa;
ate_match_fn_t match_fn = NULL;
-
- if (static_branch_unlikely(&arch_timer_read_ool_enabled))
- return;
+ bool local = false;

switch (type) {
case ate_match_dt:
@@ -262,14 +267,27 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t
case ate_match_global_cap_id:
match_fn = arch_timer_check_global_cap_erratum;
break;
+ case ate_match_local_cap_id:
+ match_fn = arch_timer_check_local_cap_erratum;
+ local = true;
+ break;
}

wa = arch_timer_iterate_errata(type, match_fn, arg);
if (!wa)
return;

+ if (static_branch_unlikely(&arch_timer_read_ool_enabled)) {
+ if (wa != timer_unstable_counter_workaround)
+ pr_warn("Can't enable workaround for %s (clashes with %s\n)",
+ wa->desc,
+ timer_unstable_counter_workaround->desc);
+ return;
+ }
+
arch_timer_enable_workaround(wa);
- pr_info("Enabling global workaround for %s\n", wa->desc);
+ pr_info("Enabling %s workaround for %s\n",
+ local ? "local" : "global", wa->desc);
}

#else
@@ -529,6 +547,8 @@ static void __arch_timer_setup(unsigned type,
BUG();
}

+ arch_timer_check_ool_workaround(ate_match_local_cap_id, NULL);
+
erratum_workaround_set_sne(clk);
} else {
clk->features |= CLOCK_EVT_FEAT_DYNIRQ;
--
2.11.0
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