[PATCH 4.9 15/43] arm64: arch_timer: Add erratum handler for CPU-specific capability

Greg Kroah-Hartman
2022-04-06T20:15:08Z

From: Marc Zyngier <marc.zyngier@arm.com>

commit 0064030c6fd4ca6cfab42de037b2a89445beeead upstream.

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>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/arch_timer.h | 1 +
drivers/clocksource/arm_arch_timer.c | 28 ++++++++++++++++++++++++----
2 files changed, 25 insertions(+), 4 deletions(-)

--- 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_time

enum arch_timer_erratum_match_type {
ate_match_dt,
+ ate_match_local_cap_id,
};

struct arch_timer_erratum_workaround {
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -162,6 +162,13 @@ bool arch_timer_check_dt_erratum(const s
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,
@@ -192,14 +199,16 @@ static void arch_timer_check_ool_workaro
{
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;
@@ -209,8 +218,17 @@ static void arch_timer_check_ool_workaro
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
@@ -470,6 +488,8 @@ static void __arch_timer_setup(unsigned
BUG();
}

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