[PATCH v5 0/6] New RISC-V Local Interrupt Controller Driver

[Anup Patel]

This patchset provides a new RISC-V Local Interrupt Controller Driver
for managing per-CPU local interrupts. The overall approach is inspired
from the way per-CPU local interrupts are handled by Linux ARM64 and
ARM GICv3 driver.

Few advantages of this new driver over previous one are:
1. All local interrupts are registered as per-CPU interrupts
2. The RISC-V timer driver can register timer interrupt handler
   using kernel irq subsystem without relying on arch/riscv to
   explicitly call it's interrupt handler
3. The KVM RISC-V can use this driver to implement interrupt
   handler for per-HART guest external interrupt defined by
   the RISC-V H-Extension
4. In future, we can develop drivers for devices with per-HART
   interrupts without changing arch code or this driver (example,
   CLINT timer driver for RISC-V M-mode kernel)

With this patchset, output of "cat /proc/interrupts" looks as follows:
           CPU0       CPU1       CPU2       CPU3       
  2:        379          0          0          0  SiFive PLIC  10  ttyS0
  3:        591          0          0          0  SiFive PLIC   8  virtio0
  5:       5079      10821       8435      12984  RISC-V INTC   5  riscv-timer
IPI0:      2045       2537        891        870  Rescheduling interrupts
IPI1:         9        269         91        168  Function call interrupts
IPI2:         0          0          0          0  CPU stop interrupts

The patchset is based up Linux-5.7-rc6 and can be found 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)

Changes since v4:
 - Rebased to Linux-5.7-rc6 and multi-PLIC improvement patches
 - Added separate patch to force select RISCV_INTC for CONFIG_RISCV
 - Fixed the driver for Linux RISC-V NoMMU

Changes since v3:
 - Rebased to Linux-5.6-rc5 and Atish's PLIC patches
 - Added separate patch to rename and move plic_find_hart_id()
   to arch directory
 - Use riscv_of_parent_hartid() in riscv_intc_init() instead of
   atomic counter

Changes since v2:
 - Dropped PATCH2 since it was merged long-time back
 - Rebased series from Linux-4.19-rc2 to Linux-5.6-rc2

Changes since v1:
 - Removed changes related to puggable IPI triggering
 - Separate patch for self-contained IPI handling routine
 - Removed patch for GENERIC_IRQ kconfig options
 - Added patch to remove do_IRQ() function
 - Rebased upon Atish's SMP patches

Anup Patel (6):
  RISC-V: self-contained IPI handling routine
  RISC-V: Rename and move plic_find_hart_id() to arch directory
  irqchip: RISC-V per-HART local interrupt controller driver
  clocksource/drivers/timer-riscv: Use per-CPU timer interrupt
  RISC-V: Remove do_IRQ() function
  RISC-V: Force select RISCV_INTC for CONFIG_RISCV

 arch/riscv/Kconfig                     |   2 +
 arch/riscv/include/asm/irq.h           |   5 -
 arch/riscv/include/asm/processor.h     |   1 +
 arch/riscv/include/asm/smp.h           |   3 +
 arch/riscv/kernel/cpu.c                |  16 +++
 arch/riscv/kernel/entry.S              |   4 +-
 arch/riscv/kernel/irq.c                |  33 +-----
 arch/riscv/kernel/smp.c                |  11 +-
 arch/riscv/kernel/traps.c              |   2 -
 drivers/clocksource/timer-riscv.c      |  30 ++++-
 drivers/irqchip/Kconfig                |  13 +++
 drivers/irqchip/Makefile               |   1 +
 drivers/irqchip/irq-riscv-intc.c       | 150 +++++++++++++++++++++++++
 drivers/irqchip/irq-sifive-plic.c      |  52 +++++----
 include/linux/cpuhotplug.h             |   1 +
 include/linux/irqchip/irq-riscv-intc.h |  20 ++++
 16 files changed, 280 insertions(+), 64 deletions(-)
 create mode 100644 drivers/irqchip/irq-riscv-intc.c
 create mode 100644 include/linux/irqchip/irq-riscv-intc.h

-- 
2.25.1