arm64: arch_timer: Add erratum handler for CPU-specific capability

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>

1 files changed, 24 insertions, 4 deletions

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 5c5c2af74ad9..532e47fa43b3 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;