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Subject[PATCH v2 17/18] arm64: arch_timer: Allow erratum matching with ACPI OEM information
Date
Just as we're able to identify a broken platform using some DT
information, let's enable a way to spot the offenders with ACPI.

The difference is that we can only match on some OEM info instead
of implementation-specific properties. So in order to avoid the
insane multiplication of errata structures, we allow an array
of OEM descriptions to be attached to an erratum structure.

Tested-by: dann frazier <dann.frazier@canonical.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/include/asm/arch_timer.h | 1 +
drivers/clocksource/arm_arch_timer.c | 32 ++++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)

diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index 3cba3a5e4ba1..a79c6932bf3f 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -42,6 +42,7 @@ enum arch_timer_erratum_match_type {
ate_match_dt,
ate_match_global_cap_id,
ate_match_local_cap_id,
+ ate_match_acpi_oem_info,
};

struct clock_event_device;
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index ba4be5859aa4..9e8cef63e59e 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -190,6 +190,12 @@ static struct cyclecounter cyclecounter __ro_after_init = {
.mask = CLOCKSOURCE_MASK(56),
};

+struct ate_acpi_oem_info {
+ char oem_id[ACPI_OEM_ID_SIZE + 1];
+ char oem_table_id[ACPI_OEM_TABLE_ID_SIZE + 1];
+ u32 oem_revision;
+};
+
#ifdef CONFIG_FSL_ERRATUM_A008585
/*
* The number of retries is an arbitrary value well beyond the highest number
@@ -378,6 +384,28 @@ bool arch_timer_check_local_cap_erratum(const struct arch_timer_erratum_workarou
return this_cpu_has_cap((uintptr_t)wa->id);
}

+
+static
+bool arch_timer_check_acpi_oem_erratum(const struct arch_timer_erratum_workaround *wa,
+ const void *arg)
+{
+ static const struct ate_acpi_oem_info empty_oem_info = {};
+ const struct ate_acpi_oem_info *info = wa->id;
+ const struct acpi_table_header *table = arg;
+
+ /* Iterate over the ACPI OEM info array, looking for a match */
+ while (memcmp(info, &empty_oem_info, sizeof(*info))) {
+ if (!memcmp(info->oem_id, table->oem_id, ACPI_OEM_ID_SIZE) &&
+ !memcmp(info->oem_table_id, table->oem_table_id, ACPI_OEM_TABLE_ID_SIZE) &&
+ info->oem_revision == table->oem_revision)
+ return true;
+
+ info++;
+ }
+
+ return false;
+}
+
static const struct arch_timer_erratum_workaround *
arch_timer_iterate_errata(enum arch_timer_erratum_match_type type,
ate_match_fn_t match_fn,
@@ -441,6 +469,9 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t
match_fn = arch_timer_check_local_cap_erratum;
local = true;
break;
+ case ate_match_acpi_oem_info:
+ match_fn = arch_timer_check_acpi_oem_erratum;
+ break;
}

wa = arch_timer_iterate_errata(type, match_fn, arg);
@@ -1286,6 +1317,7 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)

/* Check for globally applicable workarounds */
arch_timer_check_ool_workaround(ate_match_global_cap_id, NULL);
+ arch_timer_check_ool_workaround(ate_match_acpi_oem_info, table);

arch_timer_init();
return 0;
--
2.11.0
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