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

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.

Signed-off-by Inochi Amaoto <[email protected]>

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.

Signed-off-by Inochi Amaoto <[email protected]>

drivers/irqchip/Kconfig config STARFIVE_JH8100_INTC · line 617

Quoted 4 lines · Inochi Amaoto

drivers/irqchip/Kconfig +4 -0

+config THEAD_C900_ACLINT_SSWI
+	bool "THEAD C9XX ACLINT S-mode IPI Interrupt Controller"
+	depends on RISCV
+	select IRQ_DOMAIN_HIERARCHY

Lacks
select GENERIC_IRQ_IPI_MUX

Other than that this looks good.

Thanks,

tglx

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.

Signed-off-by Inochi Amaoto <[email protected]>

---
 drivers/irqchip/Kconfig                      |  10 ++
 drivers/irqchip/Makefile                     |   1 +
 drivers/irqchip/irq-thead-c900-aclint-sswi.c | 166 +++++++++++++++++++
 include/linux/cpuhotplug.h                   |   1 +
 4 files changed, 178 insertions(+)
 create mode 100644 drivers/irqchip/irq-thead-c900-aclint-sswi.c

drivers/irqchip/Kconfig +10 -0

index 341cd9ca5a05..32671385cbb7 100644
@@ -611,6 +611,16 @@ 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
+	select IRQ_DOMAIN_HIERARCHY
+	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

drivers/irqchip/Makefile +1 -0

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

drivers/irqchip/irq-thead-c900-aclint-sswi.c new file +24 -0

new file mode 100644
index 000000000000..b96d3b81dc14
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Inochi Amaoto <[email protected]>
+ */
+
+#define pr_fmt(fmt) "thead-c900-aclint-sswi: " fmt
+#include <linux/cpu.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/pci.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/string_choices.h>
+
+#define ACLINT_xSWI_REGISTER_SIZE	4
+
+static int sswi_ipi_virq __ro_after_init;

drivers/irqchip/irq-thead-c900-aclint-sswi.c new file +132 -0

+}
+
+static void thead_aclint_sswi_ipi_handle(struct irq_desc *desc)
+{
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+
+	chained_irq_enter(chip, desc);
+
+	csr_clear(CSR_IP, IE_SIE);
+	thead_aclint_sswi_ipi_clear();
+
+	ipi_mux_process();
+
+	chained_irq_exit(chip, desc);
+}
+
+static int thead_aclint_sswi_starting_cpu(unsigned int cpu)
+{
+	enable_percpu_irq(sswi_ipi_virq, irq_get_trigger_type(sswi_ipi_virq));
+
+	return 0;
+}
+
+static int thead_aclint_sswi_dying_cpu(unsigned int cpu)
+{
+	thead_aclint_sswi_ipi_clear();
+
+	disable_percpu_irq(sswi_ipi_virq);
+
+	return 0;
+}
+
+static int __init aclint_sswi_parse_irq(struct fwnode_handle *fwnode,
+					void __iomem *reg)
+{
+	struct of_phandle_args parent;
+	unsigned long hartid;
+	u32 contexts, i;
+	int rc, cpu;
+
+	contexts = of_irq_count(to_of_node(fwnode));
+	if (!(contexts)) {
+		pr_err("%pfwP: no ACLINT SSWI context available\n", fwnode);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < contexts; i++) {
+		rc = of_irq_parse_one(to_of_node(fwnode), i, &parent);
+		if (rc)
+			return rc;
+
+		rc = riscv_of_parent_hartid(parent.np, &hartid);
+		if (rc)
+			return rc;
+
+		if (parent.args[0] != RV_IRQ_SOFT)
+			return -ENOTSUPP;
+
+		cpu = riscv_hartid_to_cpuid(hartid);
+
+		per_cpu(sswi_cpu_regs, cpu) = reg + i * ACLINT_xSWI_REGISTER_SIZE;
+	}
+
+	pr_info("%pfwP: register %u CPU%s\n", fwnode, contexts, str_plural(contexts));
+
+	return 0;
+}
+
+static int __init aclint_sswi_probe(struct fwnode_handle *fwnode)
+{
+	struct irq_domain *domain;
+	void __iomem *reg;
+	int virq, rc;
+
+	if (!is_of_node(fwnode))
+		return -EINVAL;
+
+	reg = of_iomap(to_of_node(fwnode), 0);
+	if (!reg)
+		return -ENOMEM;
+
+	/* Parse SSWI setting */
+	rc = aclint_sswi_parse_irq(fwnode, reg);
+	if (rc < 0)
+		return rc;
+
+	/* If mulitple SSWI devices are present, do not register irq again */
+	if (sswi_ipi_virq)
+		return 0;
+
+	/* Find riscv intc domain and create IPI irq mapping */
+	domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(), DOMAIN_BUS_ANY);
+	if (!domain) {
+		pr_err("%pfwP: Failed to find INTC domain\n", fwnode);
+		return -ENOENT;
+	}
+
+	sswi_ipi_virq = irq_create_mapping(domain, RV_IRQ_SOFT);
+	if (!sswi_ipi_virq) {
+		pr_err("unable to create ACLINT SSWI IRQ mapping\n");
+		return -ENOMEM;
+	}
+
+	/* Register SSWI irq and handler */
+	virq = ipi_mux_create(BITS_PER_BYTE, thead_aclint_sswi_ipi_send);
+	if (virq <= 0) {
+		pr_err("unable to create muxed IPIs\n");
+		irq_dispose_mapping(sswi_ipi_virq);
+		return virq < 0 ? virq : -ENOMEM;
+	}
+
+	irq_set_chained_handler(sswi_ipi_virq, thead_aclint_sswi_ipi_handle);
+
+	cpuhp_setup_state(CPUHP_AP_IRQ_THEAD_ACLINT_SSWI_STARTING,
+			  "irqchip/thead-aclint-sswi:starting",
+			  thead_aclint_sswi_starting_cpu,
+			  thead_aclint_sswi_dying_cpu);
+
+	riscv_ipi_set_virq_range(virq, BITS_PER_BYTE);
+
+	/* Announce that SSWI is providing IPIs */
+	pr_info("providing IPIs using THEAD ACLINT SSWI\n");
+
+	return 0;
+}
+
+static int __init aclint_sswi_early_probe(struct device_node *node,
+					  struct device_node *parent)
+{
+	return aclint_sswi_probe(&node->fwnode);
+}
+IRQCHIP_DECLARE(thead_aclint_sswi, "thead,c900-aclint-sswi", aclint_sswi_early_probe);

include/linux/cpuhotplug.h +1 -0

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,

Hi Inochi,

Quoted 76 lines · Inochi Amaoto

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.

Signed-off-by Inochi Amaoto <[email protected]>

---
 drivers/irqchip/Kconfig                      |  10 ++
 drivers/irqchip/Makefile                     |   1 +
 drivers/irqchip/irq-thead-c900-aclint-sswi.c | 166 +++++++++++++++++++
 include/linux/cpuhotplug.h                   |   1 +
 4 files changed, 178 insertions(+)
 create mode 100644 drivers/irqchip/irq-thead-c900-aclint-sswi.c

drivers/irqchip/Kconfig +10 -0

index 341cd9ca5a05..32671385cbb7 100644
@@ -611,6 +611,16 @@ 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
+	select IRQ_DOMAIN_HIERARCHY
+	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

drivers/irqchip/Makefile +1 -0

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

drivers/irqchip/irq-thead-c900-aclint-sswi.c new file +24 -0

new file mode 100644
index 000000000000..b96d3b81dc14
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Inochi Amaoto <[email protected]>
+ */
+
+#define pr_fmt(fmt) "thead-c900-aclint-sswi: " fmt
+#include <linux/cpu.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/pci.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/string_choices.h>
+
+#define ACLINT_xSWI_REGISTER_SIZE	4
+
+static int sswi_ipi_virq __ro_after_init;

drivers/irqchip/irq-thead-c900-aclint-sswi.c line 34

Quoted 10 lines

drivers/irqchip/irq-thead-c900-aclint-sswi.c new file +10 -0

+static DEFINE_PER_CPU(void __iomem *, sswi_cpu_regs);
+
+static void thead_aclint_sswi_ipi_send(unsigned int cpu)
+{
+	writel_relaxed(0x1, per_cpu(sswi_cpu_regs, cpu));
+}
+
+static void thead_aclint_sswi_ipi_clear(void)
+{
+	writel_relaxed(0x0, this_cpu_read(sswi_cpu_regs));

This isn't quite compliant with the ACLINT spec[1], which states: "Writing 0 to the least significant bit of a SETSSIP register has no effect". In a RISC-V ACLINT, only the CSR write is required to clear the interrupt.

This implementation does match the behavior of the T-HEAD CLINT extensions which are also present in C906/C910[2][3][4].

This raises the question: in the older CPUs, using this functionality requires setting the mxstatus.CLINTEE bit from M-mode. Is this still the case for the C920 CPU in SG2044? If so, the driver should check sxstatus.CLINTEE when probing.

It would also be ideal if we could support the other SoCs that use this same IP block, but with the other CLINT binding.

Regards,
Samuel

[1]: https://github.com/riscv/riscv-aclint/blob/main/riscv-aclint.adoc
[2]:
https://occ-intl-prod.oss-ap-southeast-1.aliyuncs.com/resource/XuanTie-OpenC906-UserManual.pdf
[3]:
https://github.com/XUANTIE-RV/openc906/blob/main/C906_RTL_FACTORY/gen_rtl/clint/rtl/clint_func.v#L285
[4]:
https://github.com/XUANTIE-RV/openc906/blob/main/C906_RTL_FACTORY/gen_rtl/cp0/rtl/aq_cp0_trap_csr.v#L1240

Quoted 144 lines

drivers/irqchip/irq-thead-c900-aclint-sswi.c new file +132 -0

+}
+
+static void thead_aclint_sswi_ipi_handle(struct irq_desc *desc)
+{
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+
+	chained_irq_enter(chip, desc);
+
+	csr_clear(CSR_IP, IE_SIE);
+	thead_aclint_sswi_ipi_clear();
+
+	ipi_mux_process();
+
+	chained_irq_exit(chip, desc);
+}
+
+static int thead_aclint_sswi_starting_cpu(unsigned int cpu)
+{
+	enable_percpu_irq(sswi_ipi_virq, irq_get_trigger_type(sswi_ipi_virq));
+
+	return 0;
+}
+
+static int thead_aclint_sswi_dying_cpu(unsigned int cpu)
+{
+	thead_aclint_sswi_ipi_clear();
+
+	disable_percpu_irq(sswi_ipi_virq);
+
+	return 0;
+}
+
+static int __init aclint_sswi_parse_irq(struct fwnode_handle *fwnode,
+					void __iomem *reg)
+{
+	struct of_phandle_args parent;
+	unsigned long hartid;
+	u32 contexts, i;
+	int rc, cpu;
+
+	contexts = of_irq_count(to_of_node(fwnode));
+	if (!(contexts)) {
+		pr_err("%pfwP: no ACLINT SSWI context available\n", fwnode);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < contexts; i++) {
+		rc = of_irq_parse_one(to_of_node(fwnode), i, &parent);
+		if (rc)
+			return rc;
+
+		rc = riscv_of_parent_hartid(parent.np, &hartid);
+		if (rc)
+			return rc;
+
+		if (parent.args[0] != RV_IRQ_SOFT)
+			return -ENOTSUPP;
+
+		cpu = riscv_hartid_to_cpuid(hartid);
+
+		per_cpu(sswi_cpu_regs, cpu) = reg + i * ACLINT_xSWI_REGISTER_SIZE;
+	}
+
+	pr_info("%pfwP: register %u CPU%s\n", fwnode, contexts, str_plural(contexts));
+
+	return 0;
+}
+
+static int __init aclint_sswi_probe(struct fwnode_handle *fwnode)
+{
+	struct irq_domain *domain;
+	void __iomem *reg;
+	int virq, rc;
+
+	if (!is_of_node(fwnode))
+		return -EINVAL;
+
+	reg = of_iomap(to_of_node(fwnode), 0);
+	if (!reg)
+		return -ENOMEM;
+
+	/* Parse SSWI setting */
+	rc = aclint_sswi_parse_irq(fwnode, reg);
+	if (rc < 0)
+		return rc;
+
+	/* If mulitple SSWI devices are present, do not register irq again */
+	if (sswi_ipi_virq)
+		return 0;
+
+	/* Find riscv intc domain and create IPI irq mapping */
+	domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(), DOMAIN_BUS_ANY);
+	if (!domain) {
+		pr_err("%pfwP: Failed to find INTC domain\n", fwnode);
+		return -ENOENT;
+	}
+
+	sswi_ipi_virq = irq_create_mapping(domain, RV_IRQ_SOFT);
+	if (!sswi_ipi_virq) {
+		pr_err("unable to create ACLINT SSWI IRQ mapping\n");
+		return -ENOMEM;
+	}
+
+	/* Register SSWI irq and handler */
+	virq = ipi_mux_create(BITS_PER_BYTE, thead_aclint_sswi_ipi_send);
+	if (virq <= 0) {
+		pr_err("unable to create muxed IPIs\n");
+		irq_dispose_mapping(sswi_ipi_virq);
+		return virq < 0 ? virq : -ENOMEM;
+	}
+
+	irq_set_chained_handler(sswi_ipi_virq, thead_aclint_sswi_ipi_handle);
+
+	cpuhp_setup_state(CPUHP_AP_IRQ_THEAD_ACLINT_SSWI_STARTING,
+			  "irqchip/thead-aclint-sswi:starting",
+			  thead_aclint_sswi_starting_cpu,
+			  thead_aclint_sswi_dying_cpu);
+
+	riscv_ipi_set_virq_range(virq, BITS_PER_BYTE);
+
+	/* Announce that SSWI is providing IPIs */
+	pr_info("providing IPIs using THEAD ACLINT SSWI\n");
+
+	return 0;
+}
+
+static int __init aclint_sswi_early_probe(struct device_node *node,
+					  struct device_node *parent)
+{
+	return aclint_sswi_probe(&node->fwnode);
+}
+IRQCHIP_DECLARE(thead_aclint_sswi, "thead,c900-aclint-sswi", aclint_sswi_early_probe);

include/linux/cpuhotplug.h +1 -0

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,