[PATCH RFC 0/7] spacemit: k3: Replace bad CLINT node with ACLINT nodes

[Junhui Liu]

When testing OpenSBI with the upstream Device Tree, the CLINT controller
failed to function properly with the irqchip.riscv_imsic_noipi boot
parameter:

  Platform IPI Device         : aclint-mswi
  Platform Timer Device       : aclint-mtimer @ 24000000Hz
  
  Domain0 Region03            : 0x00000000e081c000-0x00000000e081ffff M: (I,R,W) S/U: ()
  
  [    0.091014] smp: Bringing up secondary CPUs ...
  [   10.104917] CPU1 failed to report alive state
  [   20.118689] CPU2 failed to report alive state
  [   30.132288] CPU3 failed to report alive state
  [   40.145953] CPU4 failed to report alive state
  [   50.159604] CPU5 failed to report alive state
  [   60.173212] CPU6 failed to report alive state
  [   70.186981] CPU7 failed to report alive state
  [   70.191411] smp: Brought up 1 node, 1 CPU

Through exploring and testing, I discovered that the K3 actually
provides all three complete ACLINT components, and subsequent
confirmation with the vendor yielded the following information:

The ACLINT controllers are mapped to two physical memory regions:
secure (0xf1810000-0xf1820000) and non-secure (0xe0810000-0xe0820000),
with varying accessibility per controller and execution mode:

+---------+--------+------------------------+-----------------------+
| Offset  | Module | Secure Region          | Non-Secure Region     |
+---------+--------+------------------------+-----------------------+
| +0x0000 | MSWI   | 0xf1810000-0xf1813fff  | 0xe0810000-0xe0813fff |
|         |        | (M-mode only)          | (Inaccessible)        |
+---------+--------+------------------------+-----------------------+
| +0x4000 | MTIMER | 0xf1814000-0xf181bfff  | 0xe0814000-0xe081bfff |
|         |        | (M-mode only)          | (Inaccessible)        |
+---------+--------+------------------------+-----------------------+
| +0xc000 | SSWI   | 0xf181c000-0xf181ffff  | 0xe081c000-0xe081ffff |
|         |        | (M-mode only if efused)| (M/S-mode Accessible) |
+---------+--------+------------------------+-----------------------+

Taking these constraints into account, we choose the secure region
(0xf1810000-0xf181bfff) for the M-mode ACLINT components (MSWI and
MTIMER), and the non-secure region (0xe081c000-0xe081ffff) for the
S-mode SSWI component.

This series is marked as RFC to discuss the ACLINT compatible string
strategy. Existing ACLINT compatibles in upstream carry specific quirks
(e.g., Nuclei/T-Head MTIMER requiring 32-bit MMIO access, or MIPS SSWI
adding extra DT properties). This series introduces the standard generic
"riscv,aclint-*" fallback compatibles, similar to "riscv,imsics" and
"riscv,aplic", to prevent constantly updating drivers for future SoCs.

Feedback is welcomed on this approach versus potential alternatives,
such as using standalone "spacemit,k3-aclint-*" compatibles without
fallbacks, or selecting distinct existing fallbacks per ACLINT
sub-module to bypass known vendor quirks.

Signed-off-by: Junhui Liu <junhui.liu at pigmoral.tech>
---
Junhui Liu (7):
      dt-bindings: timer: thead,c900-aclint-mtimer: Add SpacemiT K3
      dt-bindings: interrupt-controller: thead,c900-aclint-mswi: Add SpacemiT K3
      dt-bindings: interrupt-controller: thead,c900-aclint-sswi: Add SpacemiT K3
      dt-bindings: timer: sifive,clint: Mark spacemit,k3-clint as deprecated
      irqchip/aclint-sswi: Add generic riscv,aclint-sswi match
      riscv: dts: spacemit: k3: Fix SSWI node misidentified as CLINT
      riscv: dts: spacemit: k3: Add ACLINT MSWI and MTIMER nodes

 .../thead,c900-aclint-mswi.yaml                    |  4 +++
 .../thead,c900-aclint-sswi.yaml                    |  4 +++
 .../devicetree/bindings/timer/sifive,clint.yaml    |  5 ++-
 .../bindings/timer/thead,c900-aclint-mtimer.yaml   |  4 +++
 arch/riscv/boot/dts/spacemit/k3.dtsi               | 37 ++++++++++++++++------
 drivers/irqchip/irq-aclint-sswi.c                  |  1 +
 6 files changed, 44 insertions(+), 11 deletions(-)
---
base-commit: 46380e4b1534c1626cecd7f4d0abb5e0cce09af6
change-id: 20260729-k3-aclint-94ca9d3f818f

Best regards,
--  
Junhui Liu <junhui.liu at pigmoral.tech>