clocksource/drivers/arm_arch_timer: validate arch_timer_rate (c265861a) · Commits · 戴 / test

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>

drivers/clocksource/arm_arch_timer.c

+15 −3

Original line number	Diff line number	Diff line
		@@ -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();

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