On 21/07/2020 13:49, Anup Patel wrote:
> On Tue, Jul 21, 2020 at 4:32 PM Daniel Lezcano
> <daniel.lezcano@xxxxxxxxxx> wrote:
>>
>> On 17/07/2020 09:50, Anup Patel wrote:
>>> We add a separate CLINT timer driver for Linux RISC-V M-mode (i.e.
>>> RISC-V NoMMU kernel).
>>>
>>> The CLINT MMIO device provides three things:
>>> 1. 64bit free running counter register
>>> 2. 64bit per-CPU time compare registers
>>> 3. 32bit per-CPU inter-processor interrupt registers
>>>
>>> Unlike other timer devices, CLINT provides IPI registers along with
>>> timer registers. To use CLINT IPI registers, the CLINT timer driver
>>> provides IPI related callbacks to arch/riscv.
>>>
>>> Signed-off-by: Anup Patel <anup.patel@xxxxxxx>
>>> Tested-by: Emil Renner Berhing <kernel@xxxxxxxx>
>>> ---
>>> drivers/clocksource/Kconfig | 9 ++
>>> drivers/clocksource/Makefile | 1 +
>>> drivers/clocksource/timer-clint.c | 231 ++++++++++++++++++++++++++++++
>>> include/linux/cpuhotplug.h | 1 +
>>> 4 files changed, 242 insertions(+)
>>> create mode 100644 drivers/clocksource/timer-clint.c
>>>
>>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>>> index 91418381fcd4..e1ce0d510a03 100644
>>> --- a/drivers/clocksource/Kconfig
>>> +++ b/drivers/clocksource/Kconfig
>>> @@ -658,6 +658,15 @@ config RISCV_TIMER
>>> is accessed via both the SBI and the rdcycle instruction. This is
>>> required for all RISC-V systems.
>>>
>>> +config CLINT_TIMER
>>> + bool "Timer for the RISC-V platform"
>>> + depends on GENERIC_SCHED_CLOCK && RISCV_M_MODE
>>> + select TIMER_PROBE
>>> + select TIMER_OF
>>> + help
>>> + This option enables the CLINT timer for RISC-V systems. The CLINT
>>> + driver is usually used for NoMMU RISC-V systems.
>>
>> V3 has a comment about fixing the Kconfig option.
>
> I have removed "default y" from the Kconfig option as-per your suggestions.
>
> I looked at other Timer Kconfig options. Most of them have menuconfig name.
> Also, we can certainly have different timer MMIO timer drivers in future. Do
> you still insist on making this kconfig option totally silent ??
Yes, and there is an effort to change the entries to be silent as much
as possible.
Just add:
bool "Timer for the RISC-V platform" if COMPILE_TEST
and remove the RISCV_M_MODE dependency.
Or alternatively:
replace the RISCV_M_MODE dependency with COMPILE_TEST
The goal is to be able to compile the driver on different platforms for
compilation test covering.
Then when more mmio drivers will added we will figure out.
>> [ ... ]
>>
>>> +{
>>> + bool *registered = per_cpu_ptr(&clint_clock_event_registered, cpu);
>>> + struct clock_event_device *ce = per_cpu_ptr(&clint_clock_event, cpu);
>>> +
>>> + if (!(*registered)) {
>>> + ce->cpumask = cpumask_of(cpu);
>>> + clockevents_config_and_register(ce, clint_timer_freq, 200,
>>> + ULONG_MAX);
>>> + *registered = true;
>>> + }
>>
>>
>> I was unsure about the clockevents_config_and_register() multiple calls
>> when doing the comment. It seems like it is fine to call it several
>> times and that is done in several places like riscv or arch_arm_timer.
>>
>> It is probably safe to drop the 'registered' code here, sorry for the
>> confusion.
>
> Okay, will revert these changes.
>
>>
>>> + enable_percpu_irq(clint_timer_irq,
>>> + irq_get_trigger_type(clint_timer_irq));
>>> + return 0;
>>> +}
>>> +
>>
>> [ ... ]
>>
>>
>> --
>> <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
>>
>> Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
>> <http://twitter.com/#!/linaroorg> Twitter |
>> <http://www.linaro.org/linaro-blog/> Blog
>
> Regards,
> Anup
>
--
<http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog
