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authorIonela Voinescu <ionela.voinescu@arm.com>2020-03-05 09:06:27 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2020-03-06 16:02:51 +0000
commitc265861af2af0f667e88b1b70acc234f8c61e0ae (patch)
treef36f6f925eba70829a5d62aac147839d7360e75e /drivers/clocksource
parentcd0ed03a8903a0b0c6fc36e32d133d1ddfe70cd6 (diff)
clocksource/drivers/arm_arch_timer: validate arch_timer_rate
Using an arch timer with a frequency of less than 1MHz can potentially result in incorrect functionality in systems that assume a reasonable rate of the arch timer of 1 to 50MHz, described as typical in the architecture specification. Therefore, warn if the arch timer rate is below 1MHz, which is considered atypical and worth emphasizing. Suggested-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com> Acked-by: Marc Zyngier <maz@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'drivers/clocksource')
-rw-r--r--drivers/clocksource/arm_arch_timer.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 9a5464c625b4..4faa930eabf8 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -885,6 +885,17 @@ static int arch_timer_starting_cpu(unsigned int cpu)
return 0;
}
+static int validate_timer_rate(void)
+{
+ if (!arch_timer_rate)
+ return -EINVAL;
+
+ /* Arch timer frequency < 1MHz can cause trouble */
+ WARN_ON(arch_timer_rate < 1000000);
+
+ return 0;
+}
+
/*
* For historical reasons, when probing with DT we use whichever (non-zero)
* rate was probed first, and don't verify that others match. If the first node
@@ -900,7 +911,7 @@ static void arch_timer_of_configure_rate(u32 rate, struct device_node *np)
arch_timer_rate = rate;
/* Check the timer frequency. */
- if (arch_timer_rate == 0)
+ if (validate_timer_rate())
pr_warn("frequency not available\n");
}
@@ -1594,9 +1605,10 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
* CNTFRQ value. This *must* be correct.
*/
arch_timer_rate = arch_timer_get_cntfrq();
- if (!arch_timer_rate) {
+ ret = validate_timer_rate();
+ if (ret) {
pr_err(FW_BUG "frequency not available.\n");
- return -EINVAL;
+ return ret;
}
arch_timer_uses_ppi = arch_timer_select_ppi();