Messages in this thread Patch in this message | | | Date | Thu, 05 Feb 2015 18:11:47 +0800 | From | Hanjun Guo <> | Subject | Re: [PATCH v8 17/21] clocksource / arch_timer: Parse GTDT to initialize arch timer |
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Hi Lorenzo,
On 2015年02月05日 02:59, Lorenzo Pieralisi wrote: > On Mon, Feb 02, 2015 at 12:45:45PM +0000, Hanjun Guo wrote: >> Using the information presented by GTDT (Generic Timer Description Table) >> to initialize the arch timer (not memory-mapped). > > Why are you not initializing the memory mapped timer ?
We left it for later work because no need for that to boot available ARM64 hardware at now, and we have no hardware to test unless I missed some of platforms.
> >> CC: Daniel Lezcano <daniel.lezcano@linaro.org> >> Originally-by: Amit Daniel Kachhap <amit.daniel@samsung.com> >> Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> >> Tested-by: Yijing Wang <wangyijing@huawei.com> >> Tested-by: Mark Langsdorf <mlangsdo@redhat.com> >> Tested-by: Jon Masters <jcm@redhat.com> >> Tested-by: Timur Tabi <timur@codeaurora.org> >> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org> >> --- >> arch/arm64/kernel/time.c | 7 ++ >> drivers/clocksource/arm_arch_timer.c | 132 ++++++++++++++++++++++++++++------- >> include/linux/clocksource.h | 6 ++ >> 3 files changed, 118 insertions(+), 27 deletions(-) >> >> diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c >> index 1a7125c..42f9195 100644 >> --- a/arch/arm64/kernel/time.c >> +++ b/arch/arm64/kernel/time.c >> @@ -35,6 +35,7 @@ >> #include <linux/delay.h> >> #include <linux/clocksource.h> >> #include <linux/clk-provider.h> >> +#include <linux/acpi.h> >> >> #include <clocksource/arm_arch_timer.h> >> >> @@ -72,6 +73,12 @@ void __init time_init(void) >> >> tick_setup_hrtimer_broadcast(); >> >> + /* >> + * Since ACPI or FDT will only one be available in the system, >> + * we can use acpi_generic_timer_init() here safely >> + */ >> + acpi_generic_timer_init(); >> + >> arch_timer_rate = arch_timer_get_rate(); >> if (!arch_timer_rate) >> panic("Unable to initialise architected timer.\n"); >> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c >> index 095c177..407aa63 100644 >> --- a/drivers/clocksource/arm_arch_timer.c >> +++ b/drivers/clocksource/arm_arch_timer.c >> @@ -21,6 +21,7 @@ >> #include <linux/io.h> >> #include <linux/slab.h> >> #include <linux/sched_clock.h> >> +#include <linux/acpi.h> >> >> #include <asm/arch_timer.h> >> #include <asm/virt.h> >> @@ -370,8 +371,12 @@ arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np) >> if (arch_timer_rate) >> return; >> >> - /* Try to determine the frequency from the device tree or CNTFRQ */ >> - if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { >> + /* >> + * Try to determine the frequency from the device tree or CNTFRQ, >> + * if ACPI is enabled, get the frequency from CNTFRQ ONLY. >> + */ >> + if (!acpi_disabled || >> + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { > > This is getting a mess. cntbase tells you it is a memory mapped timer, > node pointer that you are probing through DT, and to top it all > acpi_disabled detects if you are probing in ACPI or DT mode. > > I think this function should be simplified, this driver is also > pending a refactoring to split arch timer and the memory mapped one > so I think you'd better wait that work to make things simpler.
Does anyone working on this now?
> > [...] > >> +/* Initialize all the generic timers presented in GTDT */ >> +void __init acpi_generic_timer_init(void) >> +{ >> + if (acpi_disabled) >> + return; > > acpi_disabled used again here, I repeat myself this is going to be > hard to track. You should try to organize the code something like: > > if (acpi_disabled) > timer_dt_probe(); > else > timer_acpi_probe(); > > mixing the code paths is getting unwieldy, see above to see my > reasoning.
Olof is unhappy with such approach, I think if (acpi_disabled) is self-contained because we only get DT or ACPI in the system, we can call this function time_init() without more if (acpi_disabled).
> >> + >> + acpi_table_parse(ACPI_SIG_GTDT, arch_timer_acpi_init); >> +} >> +#endif >> diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h >> index abcafaa..af6155a 100644 >> --- a/include/linux/clocksource.h >> +++ b/include/linux/clocksource.h >> @@ -346,4 +346,10 @@ extern void clocksource_of_init(void); >> static inline void clocksource_of_init(void) {} >> #endif >> >> +#ifdef CONFIG_ACPI >> +void acpi_generic_timer_init(void); >> +#else >> +static inline void acpi_generic_timer_init(void) { } >> +#endif >> + > > That's not nice, it is a generic header, arch specific stuff should be > avoided. I think you should have an ACPI generic layer similar to > clocksource_of_init(), and probe from there when matching the respective > timers.
I think I'm OK with it, but do we really need to introduce a heavy framework to init just arm arch timer (memory mapped or not) ?
Thanks Hanjun
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