[PATCH v5 7/7] clocksource/drivers/arm_arch_timer: validate arch_timer_rate
From: Ionela Voinescu <hidden>
Date: 2020-02-26 13:31:07
Also in:
linux-doc, linux-pm, lkml
Subsystem:
arm architected timer driver, clocksource, clockevent drivers, the rest · Maintainers:
Mark Rutland, Marc Zyngier, Daniel Lezcano, Thomas Gleixner, Linus Torvalds
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. Signed-off-by: Ionela Voinescu <redacted> Suggested-by: Valentin Schneider <redacted> Acked-by: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Marc Zyngier <maz@kernel.org> --- drivers/clocksource/arm_arch_timer.c | 18 +++++++++++++++--- 1 file 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();
--
2.17.1
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