Re: [PATCH v6 0/4] Dedicated CLINT timer driver

[Anup Patel]

On Wed, Aug 5, 2020 at 7:17 AM Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote:
>
> On Fri, 24 Jul 2020 00:18:18 PDT (-0700), Anup Patel wrote:
> > The current RISC-V timer driver is convoluted and implements two
> > distinct timers:
> >  1. S-mode timer: This is for Linux RISC-V S-mode with MMU. The
> >     clocksource is implemented using TIME CSR and clockevent device
> >     is implemented using SBI Timer calls.
> >  2. M-mode timer: This is for Linux RISC-V M-mode without MMU. The
> >     clocksource is implemented using CLINT MMIO time register and
> >     clockevent device is implemented using CLINT MMIO timecmp registers.
> >
> > This patchset removes clint related code from RISC-V timer driver and
> > arch/riscv directory. Instead, the series adds a dedicated MMIO based
> > CLINT driver under drivers/clocksource directory which can be used by
> > Linux RISC-V M-mode (i.e NoMMU Linux RISC-V).
> >
> > The patchset is based up Linux-5.8-rc6 and can be found at riscv_clint_v6
> > branch of: https://github.com/avpatel/linux.git
> >
> > This series is tested on:
> >  1. QEMU RV64 virt machine using Linux RISC-V S-mode
> >  2. QEMU RV32 virt machine using Linux RISC-V S-mode
> >  3. QEMU RV64 virt machine using Linux RISC-V M-mode (i.e. NoMMU)
> >
> > Changes since v5:
> >  - Fixed order of compatible strings in PATCH4
> >  - Added "additionalProperties: false" in PATCH4
> >  - Fixed register space size for example DT node in PATCH4
> >
> > Changes since v4:
> >  - Rebased series on Linux-5.8-rc6
> >  - Updated Kconfig option as suggested by Daniel in PATCH2
> >  - Removed per-CPU registered flag in PATCH2
> >  - Addressed nit comments from Atish in PATCH2
> >
> > Changes since v3:
> >  - Updated commit description of PATCH2
> >  - Use clint_get_cycles64() in clint_rdtime() of PATCH2
> >  - Call clockevents_config_and_register() only once for each CPU in
> >    clint_timer_starting_cpu of PATCH2
> >  - Select CLINT timer driver from platform Kconfig in PATCH3
> >  - Fixed 'make dt_binding_check' for PATCH4
> >
> > Changes since v2:
> >  - Rebased series on Linux-5.8-rc5
> >  - Squashed PATCH3 onto PATCH2 to preserve GIT bisectability
> >  - Moved PATCH4 before PATCH2 to preserve GIT bisectability
> >  - Replaced CLINT dt-bindings text document with YAML schema
> >  - Use SiFive CLINT compatible string as per SiFive IP block versioning
> >
> > Changes since v1:
> >  - Rebased series on Linux-5.8-rc2
> >  - Added pr_warn() for case where ipi_ops not available in PATCH1
> >  - Updated ipi_inject() prototype to use "struct cpumask *" in PATCH1
> >  - Updated CLINT_TIMER kconfig option to depend on RISCV_M_MODE in PATCH4
> >  - Added riscv,clint0 compatible string in DT bindings document
> >
> > Anup Patel (4):
> >   RISC-V: Add mechanism to provide custom IPI operations
> >   clocksource/drivers: Add CLINT timer driver
> >   RISC-V: Remove CLINT related code from timer and arch
> >   dt-bindings: timer: Add CLINT bindings
> >
> >  .../bindings/timer/sifive,clint.yaml          |  60 +++++
> >  arch/riscv/Kconfig                            |   2 +-
> >  arch/riscv/Kconfig.socs                       |   2 +
> >  arch/riscv/configs/nommu_virt_defconfig       |   7 +-
> >  arch/riscv/include/asm/clint.h                |  39 ---
> >  arch/riscv/include/asm/smp.h                  |  19 ++
> >  arch/riscv/include/asm/timex.h                |  28 +--
> >  arch/riscv/kernel/Makefile                    |   2 +-
> >  arch/riscv/kernel/clint.c                     |  44 ----
> >  arch/riscv/kernel/sbi.c                       |  14 ++
> >  arch/riscv/kernel/setup.c                     |   2 -
> >  arch/riscv/kernel/smp.c                       |  44 ++--
> >  arch/riscv/kernel/smpboot.c                   |   4 +-
> >  drivers/clocksource/Kconfig                   |  12 +-
> >  drivers/clocksource/Makefile                  |   1 +
> >  drivers/clocksource/timer-clint.c             | 226 ++++++++++++++++++
> >  drivers/clocksource/timer-riscv.c             |  17 +-
> >  include/linux/cpuhotplug.h                    |   1 +
> >  18 files changed, 371 insertions(+), 153 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/timer/sifive,clint.yaml
> >  delete mode 100644 arch/riscv/include/asm/clint.h
> >  delete mode 100644 arch/riscv/kernel/clint.c
> >  create mode 100644 drivers/clocksource/timer-clint.c
>
> Thanks, this is way cleaner.  Patchwork is still broken but IIRC we reached
> consensus on these.  I'm not going to include these in my first 5.9 PR, as I
> want to get that out tomorrow to avoid more merge conflicts, but assuming
> there's reviews from the other maintainers I'd like to take this for my second
> 5.9 merge window PR.
>
> Assuming you've been collecting reviews and acks, do you mind posting another
> version with them?  If not I have some scripts to dig them out, so it's not a
> big deal.

Most of the Reviewed-by and Ack-by are already there, except yours and
Rob Herring's Reviewed-by. I will post v7 based on Linux-5.9-rc1

Regards,
Anup