[PATCH v5 5/5] arm64: arch_timer: Add command line parameter for A-008585
From: oss@buserror.net (Scott Wood)
Date: 2016-09-10 01:03:33
Also in:
linux-devicetree
Subsystem:
arm architected timer driver, clocksource, clockevent drivers, documentation, the rest · Maintainers:
Mark Rutland, Marc Zyngier, Daniel Lezcano, Thomas Gleixner, Jonathan Corbet, Linus Torvalds
This allows KVM users to enable the workaround until a mechanism is implemented to automatically communicate this information. Signed-off-by: Scott Wood <oss@buserror.net> --- Documentation/kernel-parameters.txt | 9 +++++++++ drivers/clocksource/arm_arch_timer.c | 20 +++++++++++++++++++- 2 files changed, 28 insertions(+), 1 deletion(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a4f4d69..25037de 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt@@ -698,6 +698,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted. loops can be debugged more effectively on production systems. + clocksource.arm_arch_timer.fsl-a008585= + [ARM64] + Format: <bool> + Enable/disable the workaround of Freescale/NXP + erratum A-008585. This can be useful for KVM + guests, if the guest device tree doesn't show the + erratum. If unspecified, the workaround is + enabled based on the device tree. + clearcpuid=BITNUM [X86] Disable CPUID feature X for the kernel. See arch/x86/include/asm/cpufeatures.h for the valid bit
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 36d4ee1..e70e530 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c@@ -98,6 +98,22 @@ early_param("clocksource.arm_arch_timer.evtstrm", early_evtstrm_cfg); DEFINE_STATIC_KEY_FALSE(arch_timer_read_ool_enabled); EXPORT_SYMBOL_GPL(arch_timer_read_ool_enabled); +static int fsl_a008585_enable = -1; + +static int __init early_fsl_a008585_cfg(char *buf) +{ + int ret; + bool val; + + ret = strtobool(buf, &val); + if (ret) + return ret; + + fsl_a008585_enable = val; + return 0; +} +early_param("clocksource.arm_arch_timer.fsl-a008585", early_fsl_a008585_cfg); + /* * __always_inline is used to ensure that func() is not an actual function * pointer, which would result in the register accesses potentially being too
@@ -895,7 +911,9 @@ static int __init arch_timer_of_init(struct device_node *np) arch_timer_c3stop = !of_property_read_bool(np, "always-on"); #ifdef CONFIG_FSL_ERRATUM_A008585 - if (of_property_read_bool(np, "fsl,erratum-a008585")) + if (fsl_a008585_enable < 0) + fsl_a008585_enable = of_property_read_bool(np, "fsl,erratum-a008585"); + if (fsl_a008585_enable) static_branch_enable(&arch_timer_read_ool_enabled); #endif
--
2.7.4