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Subject[PATCH 07/29] arm64: arch_timer: Add erratum handler for CPU-specific capability
Date
From: Marc Zyngier <marc.zyngier@arm.com>

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.

Acked-by: Thomas Gleixner <tglx@linutronix.de>
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 5cd964e..1b0d7e9 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -39,6 +39,7 @@ extern struct static_key_false arch_timer_read_ool_enabled;

enum arch_timer_erratum_match_type {
ate_match_dt,
+ 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 5c5c2af..532e47fa 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -214,6 +214,13 @@ bool arch_timer_check_dt_erratum(const struct arch_timer_erratum_workaround *wa,
return of_property_read_bool(np, 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,
@@ -244,14 +251,16 @@ 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:
match_fn = arch_timer_check_dt_erratum;
break;
+ case ate_match_local_cap_id:
+ match_fn = arch_timer_check_local_cap_erratum;
+ local = true;
+ break;
default:
WARN_ON(1);
return;
@@ -261,8 +270,17 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t
if (!wa)
return;

+ if (needs_unstable_timer_counter_workaround()) {
+ 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
@@ -522,6 +540,8 @@ 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;
--
2.7.4
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