[PATCH v3 07/18] arm64: arch_timer: Add erratum handler for CPU-specific capability

[Marc Zyngier]

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.zyng...@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 5cd964e90d11..1b0d7e994e0c 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 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;
-- 
2.11.0