The RISC-V ACLINT defines MSWI and SSWI devices for M-mode and
S-mode software interrupts respectively. We add irqchip driver
which provide IPI operations based on ACLINT [M|S]SWI devices
to the Linux RISC-V kernel.
Signed-off-by: Anup Patel <anup.patel@xxxxxxx>
---
drivers/irqchip/Kconfig | 9 +
drivers/irqchip/Makefile | 1 +
drivers/irqchip/irq-riscv-aclint-swi.c | 282 +++++++++++++++++++
include/linux/irqchip/irq-riscv-aclint-swi.h | 19 ++
4 files changed, 311 insertions(+)
create mode 100644 drivers/irqchip/irq-riscv-aclint-swi.c
create mode 100644 include/linux/irqchip/irq-riscv-aclint-swi.h
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index aca7b595c4c7..c354d0576b1a 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -509,6 +509,15 @@ config RISCV_INTC
If you don't know what to do here, say Y.
+config RISCV_ACLINT_SWI
+ bool "RISC-V Advanced Core Local Interruptor Software Interrupts"
+ depends on RISCV
+ help
+ This enables support for software interrupts using the Advanced
+ Core Local Interruptor (ACLINT) found in RISC-V systems. The
+ RISC-V ACLINT provides devices for inter-process interrupt and
+ timer functionality.
+
config SIFIVE_PLIC
bool "SiFive Platform-Level Interrupt Controller"
depends on RISCV
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index f88cbf36a9d2..81306d560972 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -97,6 +97,7 @@ obj-$(CONFIG_QCOM_PDC) += qcom-pdc.o
obj-$(CONFIG_CSKY_MPINTC) += irq-csky-mpintc.o
obj-$(CONFIG_CSKY_APB_INTC) += irq-csky-apb-intc.o
obj-$(CONFIG_RISCV_INTC) += irq-riscv-intc.o
+obj-$(CONFIG_RISCV_ACLINT_SWI) += irq-riscv-aclint-swi.o
obj-$(CONFIG_SIFIVE_PLIC) += irq-sifive-plic.o
obj-$(CONFIG_IMX_IRQSTEER) += irq-imx-irqsteer.o
obj-$(CONFIG_IMX_INTMUX) += irq-imx-intmux.o
diff --git a/drivers/irqchip/irq-riscv-aclint-swi.c b/drivers/irqchip/irq-riscv-aclint-swi.c
new file mode 100644
index 000000000000..ffd16cb795ba
--- /dev/null
+++ b/drivers/irqchip/irq-riscv-aclint-swi.c
@@ -0,0 +1,282 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ */
+
+#define pr_fmt(fmt) "aclint-swi: " fmt
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqchip/irq-riscv-aclint-swi.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/smp.h>
+
+struct aclint_swi {
+ void __iomem *sip_reg;
+ unsigned long bits;
+};
+
+static int aclint_swi_parent_irq __ro_after_init;
+static struct irq_domain *aclint_swi_domain __ro_after_init;
+static DEFINE_PER_CPU(struct aclint_swi, aclint_swis);
+
+static void aclint_swi_dummy(struct irq_data *d)
+{
+}
+
+static void aclint_swi_send_mask(struct irq_data *d,
+ const struct cpumask *mask)
+{
+ int cpu;
+ struct aclint_swi *swi;
+
+ /* Barrier before doing atomic bit update to IPI bits */
+ smp_mb__before_atomic();
+
+ for_each_cpu(cpu, mask) {
+ swi = per_cpu_ptr(&aclint_swis, cpu);
+ set_bit(d->hwirq, &swi->bits);
+ writel(1, swi->sip_reg);
+ }
+
+ /* Barrier after doing atomic bit update to IPI bits */
+ smp_mb__after_atomic();
+}
+
+static struct irq_chip aclint_swi_chip = {
+ .name = "RISC-V ACLINT SWI",
+ .irq_mask = aclint_swi_dummy,
+ .irq_unmask = aclint_swi_dummy,
+ .ipi_send_mask = aclint_swi_send_mask,
+};
+
+static int aclint_swi_domain_map(struct irq_domain *d, unsigned int irq,
+ irq_hw_number_t hwirq)
+{
+ irq_set_percpu_devid(irq);
+ irq_domain_set_info(d, irq, hwirq, &aclint_swi_chip, d->host_data,
+ handle_percpu_devid_irq, NULL, NULL);
+
+ return 0;
+}
+
+static int aclint_swi_domain_alloc(struct irq_domain *d, unsigned int virq,
+ unsigned int nr_irqs, void *arg)
+{
+ int i, ret;
+ irq_hw_number_t hwirq;
+ unsigned int type = IRQ_TYPE_NONE;
+ struct irq_fwspec *fwspec = arg;
+
+ ret = irq_domain_translate_onecell(d, fwspec, &hwirq, &type);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < nr_irqs; i++) {
+ ret = aclint_swi_domain_map(d, virq + i, hwirq + i);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static const struct irq_domain_ops aclint_swi_domain_ops = {
+ .translate = irq_domain_translate_onecell,
+ .alloc = aclint_swi_domain_alloc,
+ .free = irq_domain_free_irqs_top,
+};
+
+static void aclint_swi_handle_irq(struct irq_desc *desc)
+{
+ int err;
+ unsigned long irqs;
+ irq_hw_number_t hwirq;
+ struct irq_chip *chip = irq_desc_get_chip(desc);
+ struct aclint_swi *swi = this_cpu_ptr(&aclint_swis);
+
+ chained_irq_enter(chip, desc);
+
+ while (true) {
+#ifdef CONFIG_RISCV_M_MODE
+ writel(0, swi->sip_reg);
+#else
+ csr_clear(CSR_IP, IE_SIE);
+#endif
+
+ /* Order bit clearing and data access. */
+ mb();
+
+ irqs = xchg(&swi->bits, 0);
+ if (!irqs)
+ goto done;
+
+ for_each_set_bit(hwirq, &irqs, BITS_PER_LONG) {
+ err = generic_handle_domain_irq(aclint_swi_domain,
+ hwirq);
+ if (unlikely(err))
+ pr_warn_ratelimited(
+ "can't find mapping for hwirq %lu\n",
+ hwirq);
+ }
+ }
+
+done:
+ chained_irq_exit(chip, desc);
+}
+
+static int aclint_swi_dying_cpu(unsigned int cpu)
+{
+ disable_percpu_irq(aclint_swi_parent_irq);
+ return 0;
+}
+
+static int aclint_swi_starting_cpu(unsigned int cpu)
+{
+ enable_percpu_irq(aclint_swi_parent_irq,
+ irq_get_trigger_type(aclint_swi_parent_irq));
+ return 0;
+}
+
+static int __init aclint_swi_domain_init(struct device_node *node)
+{
+ int virq;
+ struct irq_fwspec ipi;
+
+ /*
+ * We can have multiple ACLINT SWI devices but we only need
+ * one IRQ domain for providing per-HART (or per-CPU) IPIs.
+ */
+ if (aclint_swi_domain)
+ return 0;
+
+ aclint_swi_domain = irq_domain_add_linear(node, BITS_PER_LONG,
+ &aclint_swi_domain_ops, NULL);
+ if (!aclint_swi_domain) {
+ pr_err("unable to add ACLINT SWI IRQ domain\n");
+ return -ENOMEM;
+ }
+
+ ipi.fwnode = aclint_swi_domain->fwnode;
+ ipi.param_count = 1;
+ ipi.param[0] = 0;
+ virq = __irq_domain_alloc_irqs(aclint_swi_domain, -1, BITS_PER_LONG,
+ NUMA_NO_NODE, &ipi,
+ false, NULL);
+ if (virq <= 0) {
+ pr_err("unable to alloc IRQs from ACLINT SWI IRQ domain\n");
+ return -ENOMEM;
+ }
+
+ riscv_ipi_set_virq_range(virq, BITS_PER_LONG, true);
+
+ return 0;
+}
+
+/**
+ * aclint_swi_init() - Function to initialize ACLINT from SiFive CLINT
+ * timer driver used by NoMMU (M-mode) kernel.
+ * @node: device node pointer
+ * @base: base address of the [M|S]SWI registers
+ */
+int __init aclint_swi_init(struct device_node *node, void __iomem *base)
+{
+ int rc;
+ struct aclint_swi *swi;
+ u32 i, nr_irqs, nr_cpus = 0;
+
+ /* Iterate over each target CPU connected with this ACLINT */
+ nr_irqs = of_irq_count(node);
+ for (i = 0; i < nr_irqs; i++) {
+ struct of_phandle_args parent;
+ int cpu, hartid;
+
+ if (of_irq_parse_one(node, i, &parent)) {
+ pr_err("%pOFP: failed to parse irq %d.\n",
+ node, i);
+ continue;
+ }
+
+ if (parent.args[0] != RV_IRQ_SOFT)
+ continue;
+
+ hartid = riscv_of_parent_hartid(parent.np);
+ if (hartid < 0) {
+ pr_warn("failed to parse hart ID for irq %d.\n", i);
+ continue;
+ }
+
+ cpu = riscv_hartid_to_cpuid(hartid);
+ if (cpu < 0) {
+ pr_warn("Invalid cpuid for irq %d\n", i);
+ continue;
+ }
+
+ /* Find parent domain and register chained handler */
+ if (!aclint_swi_parent_irq && irq_find_host(parent.np)) {
+ aclint_swi_parent_irq = irq_of_parse_and_map(node, i);
+ if (aclint_swi_parent_irq) {
+ irq_set_chained_handler(aclint_swi_parent_irq,
+ aclint_swi_handle_irq);
+ cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
+ "irqchip/riscv/aclint-swi:starting",
+ aclint_swi_starting_cpu,
+ aclint_swi_dying_cpu);
+ }
+ }
+
+ swi = per_cpu_ptr(&aclint_swis, cpu);
+ swi->sip_reg = base + nr_cpus * sizeof(u32);
+ writel(0, swi->sip_reg);
+
+ nr_cpus++;
+ }
+
+ /* Create the IPI domain for ACLINT SWI device */
+ rc = aclint_swi_domain_init(node);
+ if (rc)
+ return rc;
+
+ /* Announce the ACLINT SWI device */
+ pr_info("%pOFP: providing IPIs for %d CPUs\n", node, nr_cpus);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(aclint_swi_init);
+
+static int __init aclint_swi_of_init(struct device_node *node,
+ struct device_node *parent)
+{
+ int rc;
+ void __iomem *base;
+
+ /* Map the registers */
+ base = of_iomap(node, 0);
+ if (!base) {
+ pr_err("%pOFP: could not map registers\n", node);
+ return -ENODEV;
+ }
+
+ /* Call common/exported ACLINT SWI initialization */
+ rc = aclint_swi_init(node, base);
+ if (rc) {
+ iounmap(base);
+ return rc;
+ }
+
+ return 0;
+}
+
+#ifdef CONFIG_RISCV_M_MODE
+IRQCHIP_DECLARE(riscv_aclint_swi, "riscv,aclint-mswi", aclint_swi_of_init);
+#else
+IRQCHIP_DECLARE(riscv_aclint_swi, "riscv,aclint-sswi", aclint_swi_of_init);
+#endif
diff --git a/include/linux/irqchip/irq-riscv-aclint-swi.h b/include/linux/irqchip/irq-riscv-aclint-swi.h
new file mode 100644
index 000000000000..766b7ec26667
--- /dev/null
+++ b/include/linux/irqchip/irq-riscv-aclint-swi.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __IRQ_RISCV_ACLINT_SWI_H
+#define __IRQ_RISCV_ACLINT_SWI_H
+
+#include <linux/types.h>
+
+struct device_node;
+
+#ifdef CONFIG_RISCV_ACLINT_SWI
+int aclint_swi_init(struct device_node *node, void __iomem *base);
+#else
+static inline int aclint_swi_init(struct device_node *node,
+ void __iomem *base)
+{
+ return 0;
+}
+#endif
+
+#endif /* __IRQ_RISCV_ACLINT_SWI_H */
--
2.25.1
