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

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


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