riscv: interrupt-controller: Add T-HEAD C900 ACLINT SSWI

New version of T-HEAD C920 implement a fully featured ACLINT[1] device (This core is used by Sophgo SG2044). This ACLINT device provides a SSWI field to support fast S-mode IPI. This SSWI device is like the MSWI device in CLINT/ACLINT, but for S-mode. The only thing is different from the draft is that the T-HEAD version SSWI needs to write 0 on the SSWI address to clear the IPI.

Add full support for T-HEAD C900 SSWI device.

[1] https://github.com/riscv/riscv-aclint

Changed from v1:
1. patch 2: use computed reg offset to avoid uncessary reg additions when setting/clearing irq.
2. patch 2: fix mulitple format issues and improve some comments.
3. patch 2: disable cpu irq when CPU is stopped.

Changed from v2:
1. patch 2: add SXSTATUS.CLINTEE check for T-HEAD cores.
2. patch 2: add select GENERIC_IRQ_IPI_MUX in Kconfig

Changed from v3:
2. patch 2: add SMP depends in Kconfig

Inochi Amaoto (3):
dt-bindings: interrupt-controller: Add Sophgo SG2044 ACLINT SSWI
irqchip: add T-HEAD C900 ACLINT SSWI driver
riscv: defconfig: Enable T-HEAD C900 ACLINT SSWI drivers

 .../thead,c900-aclint-sswi.yaml               |  58 ++++++
 arch/riscv/configs/defconfig                  |   1 +
 drivers/irqchip/Kconfig                       |  12 ++
 drivers/irqchip/Makefile                      |   1 +
 drivers/irqchip/irq-thead-c900-aclint-sswi.c  | 176 ++++++++++++++++++
 include/linux/cpuhotplug.h                    |   1 +
 6 files changed, 249 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/interrupt-controller/thead,c900-aclint-sswi.yaml
 create mode 100644 drivers/irqchip/irq-thead-c900-aclint-sswi.c

--
2.47.0

Sophgo SG2044 has a new version of T-HEAD C920, which implement a fully featured ACLINT device. This ACLINT has an extra SSWI field to support fast S-mode IPI.

Add necessary compatible string for the T-HEAD ACLINT sswi device.

---
 .../thead,c900-aclint-sswi.yaml               | 58 +++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/interrupt-controller/thead,c900-aclint-sswi.yaml

new file mode 100644
index 000000000000..0106fbf3ea1f
@@ -0,0 +1,58 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/interrupt-controller/thead,c900-aclint-sswi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sophgo sg2044 ACLINT Supervisor-level Software Interrupt Device
+
+maintainers:
+  - Inochi Amaoto <[email protected]>
+
+description:
+  The SSWI device is a part of the riscv ACLINT device. It provides
+  supervisor-level IPI functionality for a set of HARTs on a RISC-V
+  platform. It provides a register to set an IPI (SETSSIP) for each
+  HART connected to the SSWI device.
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - sophgo,sg2044-aclint-sswi
+      - const: thead,c900-aclint-sswi
+
+  reg:
+    maxItems: 1
+
+  "#interrupt-cells":
+    const: 0
+
+  interrupt-controller: true
+
+  interrupts-extended:
+    minItems: 1
+    maxItems: 4095
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - "#interrupt-cells"
+  - interrupt-controller
+  - interrupts-extended
+
+examples:
+  - |
+    interrupt-controller@94000000 {
+      compatible = "sophgo,sg2044-aclint-sswi", "thead,c900-aclint-sswi";
+      reg = <0x94000000 0x00004000>;
+      #interrupt-cells = <0>;
+      interrupt-controller;
+      interrupts-extended = <&cpu1intc 1>,
+                            <&cpu2intc 1>,
+                            <&cpu3intc 1>,
+                            <&cpu4intc 1>;
+    };
+...

2.47.0

Add a driver for the T-HEAD C900 ACLINT SSWI device, which is an enhanced implementation of the RISC-V ACLINT SSWI specification. This device allows the system to send ipi via fast device interface.

---
 drivers/irqchip/Kconfig                      |  12 ++
 drivers/irqchip/Makefile                     |   1 +
 drivers/irqchip/irq-thead-c900-aclint-sswi.c | 176 +++++++++++++++++++
 include/linux/cpuhotplug.h                   |   1 +
 4 files changed, 190 insertions(+)
 create mode 100644 drivers/irqchip/irq-thead-c900-aclint-sswi.c

index 341cd9ca5a05..b6e8411f28d3 100644
@@ -611,6 +611,18 @@ config STARFIVE_JH8100_INTC
 
 	  If you don't know what to do here, say Y.
 
+config THEAD_C900_ACLINT_SSWI
+	bool "THEAD C9XX ACLINT S-mode IPI Interrupt Controller"
+	depends on RISCV
+	depends on SMP
+	select IRQ_DOMAIN_HIERARCHY
+	select GENERIC_IRQ_IPI_MUX
+	help
+	  This enables support for T-HEAD specific ACLINT SSWI device
+	  support.
+
+	  If you don't know what to do here, say Y.
+
 config EXYNOS_IRQ_COMBINER
 	bool "Samsung Exynos IRQ combiner support" if COMPILE_TEST
 	depends on (ARCH_EXYNOS && ARM) || COMPILE_TEST

index e3679ec2b9f7..583418261253 100644
@@ -101,6 +101,7 @@ obj-$(CONFIG_RISCV_APLIC_MSI)		+= irq-riscv-aplic-msi.o
 obj-$(CONFIG_RISCV_IMSIC)		+= irq-riscv-imsic-state.o irq-riscv-imsic-early.o irq-riscv-imsic-platform.o
 obj-$(CONFIG_SIFIVE_PLIC)		+= irq-sifive-plic.o
 obj-$(CONFIG_STARFIVE_JH8100_INTC)	+= irq-starfive-jh8100-intc.o
+obj-$(CONFIG_THEAD_C900_ACLINT_SSWI)	+= irq-thead-c900-aclint-sswi.o
 obj-$(CONFIG_IMX_IRQSTEER)		+= irq-imx-irqsteer.o
 obj-$(CONFIG_IMX_INTMUX)		+= irq-imx-intmux.o
 obj-$(CONFIG_IMX_MU_MSI)		+= irq-imx-mu-msi.o

index 2361ed4d2b15..799052249c7b 100644
@@ -147,6 +147,7 @@ enum cpuhp_state {
 	CPUHP_AP_IRQ_EIOINTC_STARTING,
 	CPUHP_AP_IRQ_AVECINTC_STARTING,
 	CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
+	CPUHP_AP_IRQ_THEAD_ACLINT_SSWI_STARTING,
 	CPUHP_AP_IRQ_RISCV_IMSIC_STARTING,
 	CPUHP_AP_IRQ_RISCV_SBI_IPI_STARTING,
 	CPUHP_AP_ARM_MVEBU_COHERENCY,

2.47.0

Can someone from the RISCV folks please confirm that thtis is good to go?

Thanks,

tglx

Hi Thomas,

The T-HEAD C900 ACLINT SSWI is not compliant to any RISC-V specification so at this point it is a T-HEAD specific device. The RISC-V ACLINT SSWI specification cited by this driver was never ratified by RISC-V international in-favor of the ratified RISC-V AIA specification which has a much cleaner way of doing IPI (as software injected MSIs) implemented by the IMSIC driver and this also supports IPI virtualization.

Since this is a T-HEAD specific implementation, the description in all patches of this series should be updated to replace references of the RISC-V ACLINT SSWI specification with publicly available T-HEAD documentation. Once, this is done, I think this series can go ahead.

Regards,
Anup

Thanks for your kindly explanation. I will update all the description about these patch.

Regards,
Inochi

Add support for T-HEAD C900 ACLINT SSWI irqchip.

---
 arch/riscv/configs/defconfig | 1 +
 1 file changed, 1 insertion(+)

index 2341393cfac1..5b1d6325df85 100644
@@ -256,6 +256,7 @@ CONFIG_RPMSG_CTRL=y
 CONFIG_RPMSG_VIRTIO=y
 CONFIG_PM_DEVFREQ=y
 CONFIG_IIO=y
+CONFIG_THEAD_C900_ACLINT_SSWI=y
 CONFIG_PHY_SUN4I_USB=m
 CONFIG_PHY_STARFIVE_JH7110_DPHY_RX=m
 CONFIG_PHY_STARFIVE_JH7110_PCIE=m

2.47.0