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From:   Jianmin Lv <lvjianmin@loongson.cn>
To:     Thomas Gleixner <tglx@linutronix.de>, Marc Zyngier <maz@kernel.org>
Cc:     linux-kernel@vger.kernel.org, Hanjun Guo <guohanjun@huawei.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Huacai Chen <chenhuacai@gmail.com>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Huacai Chen <chenhuacai@loongson.cn>,
        Jianmin Lv <lvjianmin@loongson.cn>
Subject: [PATCH RFC V3 00/11] irqchip: Add LoongArch-related irqchip drivers
Date:   Sat, 11 Jun 2022 22:02:35 +0800
Message-Id: <1654956155-936-1-git-send-email-lvjianmin@loongson.cn>
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LoongArch is a new RISC ISA, which is a bit like MIPS or RISC-V.
LoongArch includes a reduced 32-bit version (LA32R), a standard 32-bit
version (LA32S) and a 64-bit version (LA64). LoongArch use ACPI as its
boot protocol LoongArch-specific interrupt controllers (similar to APIC)
are already added in the ACPI Specification 6.5(which may be published in
early June this year and the board is reviewing the draft).

Currently, LoongArch based processors (e.g. Loongson-3A5000) can only
work together with LS7A chipsets. The irq chips in LoongArch computers
include CPUINTC (CPU Core Interrupt Controller), LIOINTC (Legacy I/O
Interrupt Controller), EIOINTC (Extended I/O Interrupt Controller),
HTVECINTC (Hyper-Transport Vector Interrupt Controller), PCH-PIC (Main
Interrupt Controller in LS7A chipset), PCH-LPC (LPC Interrupt Controller
in LS7A chipset) and PCH-MSI (MSI Interrupt Controller).

CPUINTC is a per-core controller (in CPU), LIOINTC/EIOINTC/HTVECINTC are
per-package controllers (in CPU), while PCH-PIC/PCH-LPC/PCH-MSI are all
controllers out of CPU (i.e., in chipsets). These controllers (in other
words, irqchips) are linked in a hierarchy, and there are two models of
hierarchy (legacy model and extended model). 

Legacy IRQ model:

In this model, the IPI (Inter-Processor Interrupt) and CPU Local Timer
interrupt go to CPUINTC directly, CPU UARTS interrupts go to LIOINTC,
while all other devices interrupts go to PCH-PIC/PCH-LPC/PCH-MSI and
gathered by HTVECINTC, and then go to LIOINTC, and then CPUINTC.

 +---------------------------------------------+
 |                                             |
 |    +-----+     +---------+     +-------+    |
 |    | IPI | --> | CPUINTC | <-- | Timer |    |
 |    +-----+     +---------+     +-------+    |
 |                     ^                       |
 |                     |                       |
 |                +---------+     +-------+    |
 |                | LIOINTC | <-- | UARTs |    |
 |                +---------+     +-------+    |
 |                     ^                       |
 |                     |                       |
 |               +-----------+                 |
 |               | HTVECINTC |                 |
 |               +-----------+                 |
 |                ^         ^                  |
 |                |         |                  |
 |          +---------+ +---------+            |
 |          | PCH-PIC | | PCH-MSI |            |
 |          +---------+ +---------+            |
 |            ^     ^           ^              |
 |            |     |           |              |
 |    +---------+ +---------+ +---------+      |
 |    | PCH-LPC | | Devices | | Devices |      |
 |    +---------+ +---------+ +---------+      |
 |         ^                                   |
 |         |                                   |
 |    +---------+                              |
 |    | Devices |                              |
 |    +---------+                              |
 |                                             |
 |                                             |
 +---------------------------------------------+

Extended IRQ model:

In this model, the IPI (Inter-Processor Interrupt) and CPU Local Timer
interrupt go to CPUINTC directly, CPU UARTS interrupts go to LIOINTC,
while all other devices interrupts go to PCH-PIC/PCH-LPC/PCH-MSI and
gathered by EIOINTC, and then go to to CPUINTC directly.

 +--------------------------------------------------------+
 |                                                        |
 |         +-----+     +---------+     +-------+          |
 |         | IPI | --> | CPUINTC | <-- | Timer |          |
 |         +-----+     +---------+     +-------+          |
 |                      ^       ^                         |
 |                      |       |                         |
 |               +---------+ +---------+     +-------+    |
 |               | EIOINTC | | LIOINTC | <-- | UARTs |    |
 |               +---------+ +---------+     +-------+    |
 |                ^       ^                               |
 |                |       |                               |
 |         +---------+ +---------+                        |
 |         | PCH-PIC | | PCH-MSI |                        |
 |         +---------+ +---------+                        |
 |           ^     ^           ^                          |
 |           |     |           |                          |
 |   +---------+ +---------+ +---------+                  |
 |   | PCH-LPC | | Devices | | Devices |                  |
 |   +---------+ +---------+ +---------+                  |
 |        ^                                               |
 |        |                                               |
 |   +---------+                                          |
 |   | Devices |                                          |
 |   +---------+                                          |
 |                                                        |
 |                                                        |
 +--------------------------------------------------------+

The hierarchy model is constructed by parsing irq contronler structures
in MADT. Some controllers((e.g. LIOINTC, HTVECINTC, EIOINTC and PCH-LPC)
are hardcodingly connected to their parents, so their irqdomins are
separately routed to their parents in a fixed way. Some controllers
(e.g. PCH-PIC and PCH-MSI) could be routed to different parents for different
CPU. The firmware will config EIOINTC for the newer CPU and config HTVECINTC
for old CPU in MADT. By this way, PCH-PIC and PCH-MSI irqdomain can only be
routed one parent irqdomin: HTVECINTC or EIOINTC.


Example of irqchip topology in a system with  two chipsets:

 +------------------------------------------------------------+
 |                                                            |
 |                     +------------------+                   |
 |                     |      CPUINTC     |                   |
 |                     +------------------+                   |
 |                     ^                  ^                   |
 |                     |                  |                   |
 |          +----------+                  +----------+        |
 |          | EIOINTC 0|                  | EIOINTC 1|        |
 |          +----------+                  +----------+        |
 |          ^          ^                  ^          ^        |
 |          |          |                  |          |        |
 | +----------+   +----------+   +----------+    +----------+ |
 | | PCH-PIC 0|   | PCH-MSI 0|   | PCH-PIC 1|    | PCH-MSI 1| |
 | +----------+   +----------+   +----------+    +----------+ |
 |                                                            |
 |                                                            |
 +------------------------------------------------------------+

For systems with two chipsets, there are tow group(consists of EIOINTC, PCH-PIC and PCH-MSI) irqdomains, 
and each group has same node id. So we defined a structure to mantain the relation of node and it's parent irqdomain.

struct acpi_vector_group {
        int node;
        struct irq_domain *parent;
};

The initialization and use of acpi_vector_group array are following:

1 Entry of struct acpi_vector_group array initialization:

By parsing MCFG, the node id（from bit44-47 of Base Address）of each pci segment is extracted. And from MADT, we have the node id of each EIOINTC.

entrys[pci segment].node = node id of pci segment
entrys[pci segment].parent = EIOINTC irqdomain(node id of EIOINTC == node id of pci segment)

2 Get parent irqdomain for PCH-PIC:

From MADT, we have the node id of each PCH-PIC(from bit44-47 of Base Address).
if (node of entry i == node of PCH-PIC)
	return entrys[i].parent;

entrys[pci segment].node = node id of pci segment
entrys[pci segment].parent = EIOINTC irqdomain(node id of EIOINTC == node id of pci segment)

3 Get parent irqdomain for PCH-MSI of pci segment:

	return entrys[pci segment].parent;

4 How to select a correct irqdomain to map irq for a device?
For devices using legacy irq behind PCH-PIC, GSI is used to select correct PCH-PIC irqdomain.
For devices using msi irq behind PCH-MSI, the pci segmen of the device is used to select correct PCH-MSI irqdomain.

V1 -> V2:
1, Remove queued patches;
2, Move common logic of DT/ACPI probing to common functions;
3, Split .suspend()/.resume() functions to separate patches.

V2 -> V3:
1, Fix a bug for loongson-pch-pic probe;
2, Some minor improvements for LPC controller.

V3 -> V4:
1, Rework the CPU interrupt controller driver;
2, Some minor improvements for other controllers.

V4 -> V5:
1, Add a description of LoonArch's IRQ model;
2, Support multiple EIOINTCs in one system;
3, Some minor improvements for other controllers.

V5 -> V6:
1, Attach a fwnode to CPUINTC irq domain;
2, Use raw spinlock instead of generic spinlock;
3, Improve the method of restoring EIOINTC state;
4, Update documentation, comments and commit messages.

V6 -> V7:
1, Fix build warnings reported by kernel test robot.

V7 -> V8:
1, Add arguments sanity checking for irqchip init functions;
2, Support Loongson-3C5000 (One NUMA Node includes 4 EIOINTC Node).

V8 -> V9:
1, Rebase on 5.17-rc5;
2, Update cover letter;
3, Some small improvements.

V9 -> V10:
1, Rebase on 5.17-rc6;
2, Fix build warnings reported by kernel test robot.

V10 -> V11:
1, Rebase on 5.18-rc4;
2, Fix irq affinity setting for EIOINTC;
3, Fix hwirq allocation failure for EIOINTC.

V11 -> RFC:
1, Refactored the way to build irqchip hierarchy topology.

RFC -> RFC V2:
1, Move all IO-interrupt related code to driver/irqchip from arch directory.
2. Add description for an example of two chipsets system.

RFC V2 -> RFC V3:
1, Add support for multiple GSI domains
2, Use ACPI_GENERIC_GSI for GSI handling
3, Drop suspend-resume stuff
4, Export fwnode handles instead of irq domain handles

Huacai Chen (1):
  irqchip: Adjust Kconfig for Loongson

Jianmin Lv (10):
  APCI: irq: Add support for multiple GSI domains
  genirq/generic_chip: export irq_unmap_generic_chip
  irqchip: Add LoongArch CPU interrupt controller support
  irqchip: create library file for LoongArch irqchip driver
  irqchip/loongson-pch-pic: Add ACPI init support
  irqchip/loongson-pch-msi: Add ACPI init support
  irqchip/loongson-htvec: Add ACPI init support
  irqchip/loongson-liointc: Add ACPI init support
  irqchip: Add Loongson Extended I/O interrupt controller support
  irqchip: Add Loongson PCH LPC controller support

 drivers/acpi/bus.c                         |   3 +
 drivers/acpi/irq.c                         |  40 ++--
 drivers/irqchip/Kconfig                    |  38 +++-
 drivers/irqchip/Makefile                   |   3 +
 drivers/irqchip/irq-gic-v3.c               |  18 +-
 drivers/irqchip/irq-gic.c                  |  18 +-
 drivers/irqchip/irq-loongarch-cpu.c        | 134 +++++++++++
 drivers/irqchip/irq-loongarch-pic-common.c | 122 ++++++++++
 drivers/irqchip/irq-loongarch-pic-common.h |  39 ++++
 drivers/irqchip/irq-loongson-eiointc.c     | 347 +++++++++++++++++++++++++++++
 drivers/irqchip/irq-loongson-htvec.c       | 119 +++++++---
 drivers/irqchip/irq-loongson-liointc.c     | 232 ++++++++++++-------
 drivers/irqchip/irq-loongson-pch-lpc.c     | 202 +++++++++++++++++
 drivers/irqchip/irq-loongson-pch-msi.c     | 138 ++++++++----
 drivers/irqchip/irq-loongson-pch-pic.c     | 167 +++++++++++---
 include/linux/acpi.h                       |   3 +-
 include/linux/cpuhotplug.h                 |   1 +
 include/linux/irq.h                        |   1 +
 kernel/irq/generic-chip.c                  |   2 +-
 19 files changed, 1409 insertions(+), 218 deletions(-)
 create mode 100644 drivers/irqchip/irq-loongarch-cpu.c
 create mode 100644 drivers/irqchip/irq-loongarch-pic-common.c
 create mode 100644 drivers/irqchip/irq-loongarch-pic-common.h
 create mode 100644 drivers/irqchip/irq-loongson-eiointc.c
 create mode 100644 drivers/irqchip/irq-loongson-pch-lpc.c

-- 
1.8.3.1