[0/5] Dedicated CLINT timer driver

Message

Anup Patel May 21, 2020, 1:45 p.m. UTC

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-5.7-rc6 and can be found at riscv_clint_v1
branch of: https://github.com/avpatel/linux.git

These patches require "New RISC-V Local Interrupt Controller Driver"
which can be found at at riscv_intc_v5 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)

Anup Patel (5):
  RISC-V: Add mechanism to provide custom IPI operations
  RISC-V: Remove CLINT related code
  clocksource/drivers/timer-riscv: Remove MMIO related stuff
  clocksource/drivers: Add CLINT timer driver
  dt-bindings: timer: Add CLINT bindings

 .../bindings/timer/sifive,clint.txt           |  33 +++
 arch/riscv/Kconfig                            |   2 +-
 arch/riscv/include/asm/clint.h                |  39 ---
 arch/riscv/include/asm/smp.h                  |  11 +
 arch/riscv/include/asm/timex.h                |  28 +--
 arch/riscv/kernel/Makefile                    |   2 +-
 arch/riscv/kernel/clint.c                     |  44 ----
 arch/riscv/kernel/setup.c                     |   2 -
 arch/riscv/kernel/smp.c                       |  53 ++--
 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 +
 15 files changed, 330 insertions(+), 145 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/timer/sifive,clint.txt
 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