[PATCH v3 2/4] irqchip: RISC-V Per-HART Local Interrupt Controller Driver
From: Anup Patel
Date: Wed Feb 19 2020 - 12:16:38 EST
The RISC-V per-HART local interrupt controller manages software
interrupts, timer interrupts, external interrupts (which are routed
via the platform level interrupt controller) and per-HART local
interrupts.
This patch add a driver for RISC-V local interrupt controller. It
is a major re-write over perviously submitted version.
(Refer, https://www.spinics.net/lists/devicetree/msg241230.html)
Few advantages of this new driver over previous one are:
1. It registers all local interrupts as per-CPU interrupts
2. We can develop drivers for devices with per-CPU local interrupts
without changing arch code or this driver
3. It will be useful to direct interrupt injection in KVM RISC-V
as well
The RISC-V INTC driver is compliant with RISC-V Hart-Level Interrupt
Controller DT bindings located at:
Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Signed-off-by: Anup Patel <anup.patel@xxxxxxx>
---
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/irq.h | 2 -
arch/riscv/kernel/irq.c | 33 +------
arch/riscv/kernel/traps.c | 2 -
drivers/irqchip/Kconfig | 13 +++
drivers/irqchip/Makefile | 1 +
drivers/irqchip/irq-riscv-intc.c | 139 ++++++++++++++++++++++++++++++
drivers/irqchip/irq-sifive-plic.c | 39 ++++++++-
include/linux/cpuhotplug.h | 2 +
9 files changed, 194 insertions(+), 38 deletions(-)
create mode 100644 drivers/irqchip/irq-riscv-intc.c
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 73f029eae0cc..fe05f99357c7 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -39,6 +39,7 @@ config RISCV
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_SYSCALL_TRACEPOINTS
+ select HANDLE_DOMAIN_IRQ
select IRQ_DOMAIN
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
index 0183e15ace66..a9e5f07a7e9c 100644
--- a/arch/riscv/include/asm/irq.h
+++ b/arch/riscv/include/asm/irq.h
@@ -10,8 +10,6 @@
#include <linux/interrupt.h>
#include <linux/linkage.h>
-#define NR_IRQS 0
-
void riscv_timer_interrupt(void);
#include <asm-generic/irq.h>
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index bb0bfcd537e7..eb8777642ce6 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -7,7 +7,6 @@
#include <linux/interrupt.h>
#include <linux/irqchip.h>
-#include <linux/irqdomain.h>
#include <linux/seq_file.h>
#include <asm/smp.h>
@@ -19,39 +18,13 @@ int arch_show_interrupts(struct seq_file *p, int prec)
asmlinkage __visible void __irq_entry do_IRQ(struct pt_regs *regs)
{
- struct pt_regs *old_regs;
-
- switch (regs->cause & ~CAUSE_IRQ_FLAG) {
- case RV_IRQ_TIMER:
- old_regs = set_irq_regs(regs);
- irq_enter();
- riscv_timer_interrupt();
- irq_exit();
- set_irq_regs(old_regs);
- break;
-#ifdef CONFIG_SMP
- case RV_IRQ_SOFT:
- /*
- * We only use software interrupts to pass IPIs, so if a non-SMP
- * system gets one, then we don't know what to do.
- */
- handle_IPI(regs);
- break;
-#endif
- case RV_IRQ_EXT:
- old_regs = set_irq_regs(regs);
- irq_enter();
+ if (handle_arch_irq)
handle_arch_irq(regs);
- irq_exit();
- set_irq_regs(old_regs);
- break;
- default:
- pr_alert("unexpected interrupt cause 0x%lx", regs->cause);
- BUG();
- }
}
void __init init_IRQ(void)
{
irqchip_init();
+ if (!handle_arch_irq)
+ panic("No interrupt controller found.");
}
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index f4cad5163bf2..a62fcf4b7eed 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -156,6 +156,4 @@ void __init trap_init(void)
csr_write(CSR_SCRATCH, 0);
/* Set the exception vector address */
csr_write(CSR_TVEC, &handle_exception);
- /* Enable all interrupts */
- csr_write(CSR_IE, -1);
}
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 6d397732138d..cf7a4ce2f121 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -493,6 +493,19 @@ config TI_SCI_INTA_IRQCHIP
If you wish to use interrupt aggregator irq resources managed by the
TI System Controller, say Y here. Otherwise, say N.
+config RISCV_INTC
+ bool "RISC-V Local Interrupt Controller"
+ depends on RISCV
+ default y
+ help
+ This enables support for the per-HART local interrupt controller
+ found in standard RISC-V systems. The per-HART local interrupt
+ controller handles timer interrupts, software interrupts, and
+ hardware interrupts. Without a per-HART local interrupt controller,
+ a RISC-V system will be unable to handle any interrupts.
+
+ If you don't know what to do here, say Y.
+
config SIFIVE_PLIC
bool "SiFive Platform-Level Interrupt Controller"
depends on RISCV
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index eae0d78cbf22..31ba55d2b6fb 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -98,6 +98,7 @@ obj-$(CONFIG_NDS32) += irq-ativic32.o
obj-$(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_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-intc.c b/drivers/irqchip/irq-riscv-intc.c
new file mode 100644
index 000000000000..a2523fc663b1
--- /dev/null
+++ b/drivers/irqchip/irq-riscv-intc.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ * Copyright (C) 2017-2018 SiFive
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ */
+
+#define pr_fmt(fmt) "riscv-intc: " fmt
+#include <linux/atomic.h>
+#include <linux/bits.h>
+#include <linux/cpu.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqdomain.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/smp.h>
+
+static struct irq_domain *intc_domain;
+static atomic_t intc_init = ATOMIC_INIT(0);
+
+static asmlinkage void riscv_intc_irq(struct pt_regs *regs)
+{
+ struct pt_regs *old_regs;
+ unsigned long cause = regs->cause & ~CAUSE_IRQ_FLAG;
+
+ if (unlikely(cause >= BITS_PER_LONG))
+ panic("unexpected interrupt cause");
+
+ switch (cause) {
+ case RV_IRQ_TIMER:
+ old_regs = set_irq_regs(regs);
+ irq_enter();
+ riscv_timer_interrupt();
+ irq_exit();
+ set_irq_regs(old_regs);
+ break;
+#ifdef CONFIG_SMP
+ case RV_IRQ_SOFT:
+ /*
+ * We only use software interrupts to pass IPIs, so if a
+ * non-SMP system gets one, then we don't know what to do.
+ */
+ handle_IPI(regs);
+ break;
+#endif
+ default:
+ handle_domain_irq(intc_domain, cause, regs);
+ break;
+ }
+}
+
+/*
+ * On RISC-V systems local interrupts are masked or unmasked by writing
+ * the SIE (Supervisor Interrupt Enable) CSR. As CSRs can only be written
+ * on the local hart, these functions can only be called on the hart that
+ * corresponds to the IRQ chip.
+ */
+
+static void riscv_intc_irq_mask(struct irq_data *d)
+{
+ csr_clear(sie, 1 << (long)d->hwirq);
+}
+
+static void riscv_intc_irq_unmask(struct irq_data *d)
+{
+ csr_set(sie, 1 << (long)d->hwirq);
+}
+
+static int riscv_intc_cpu_starting(unsigned int cpu)
+{
+ csr_write(sie, 1UL << RV_IRQ_SOFT);
+ csr_write(sip, 0);
+ return 0;
+}
+
+static int riscv_intc_cpu_dying(unsigned int cpu)
+{
+ csr_clear(sie, 1UL << RV_IRQ_SOFT);
+ return 0;
+}
+
+static struct irq_chip riscv_intc_chip = {
+ .name = "RISC-V INTC",
+ .irq_mask = riscv_intc_irq_mask,
+ .irq_unmask = riscv_intc_irq_unmask,
+};
+
+static int riscv_intc_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, &riscv_intc_chip, d->host_data,
+ handle_percpu_devid_irq, NULL, NULL);
+ irq_set_status_flags(irq, IRQ_NOAUTOEN);
+
+ return 0;
+}
+
+static const struct irq_domain_ops riscv_intc_domain_ops = {
+ .map = riscv_intc_domain_map,
+ .xlate = irq_domain_xlate_onecell,
+};
+
+static int __init riscv_intc_init(struct device_node *node,
+ struct device_node *parent)
+{
+ /*
+ * RISC-V device trees can have one INTC DT node under
+ * each CPU DT node so INTC init function will be called
+ * once for each INTC DT node. We only need to do INTC
+ * init once for boot CPU so we use atomic counter to
+ * achieve this.
+ */
+ if (atomic_inc_return(&intc_init) > 1)
+ return 0;
+
+ intc_domain = irq_domain_add_linear(node, BITS_PER_LONG,
+ &riscv_intc_domain_ops, NULL);
+ if (!intc_domain)
+ goto error_add_linear;
+
+ set_handle_irq(&riscv_intc_irq);
+
+ cpuhp_setup_state(CPUHP_AP_IRQ_RISCV_STARTING,
+ "irqchip/riscv/intc:starting",
+ riscv_intc_cpu_starting,
+ riscv_intc_cpu_dying);
+
+ pr_info("%lu local interrupts mapped\n", (long)BITS_PER_LONG);
+
+ return 0;
+
+error_add_linear:
+ pr_warn("unable to add IRQ domain\n");
+ return -ENXIO;
+}
+
+IRQCHIP_DECLARE(riscv, "riscv,cpu-intc", riscv_intc_init);
diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index aa4af886e43a..a4f247a00a3c 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -4,10 +4,12 @@
* Copyright (C) 2018 Christoph Hellwig
*/
#define pr_fmt(fmt) "plic: " 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/irqdomain.h>
#include <linux/module.h>
#include <linux/of.h>
@@ -187,6 +189,7 @@ static const struct irq_domain_ops plic_irqdomain_ops = {
.free = irq_domain_free_irqs_top,
};
+static int plic_parent_irq;
static struct irq_domain *plic_irqdomain;
/*
@@ -195,15 +198,17 @@ static struct irq_domain *plic_irqdomain;
* that source ID back to the same claim register. This automatically enables
* and disables the interrupt, so there's nothing else to do.
*/
-static void plic_handle_irq(struct pt_regs *regs)
+static void plic_handle_irq(struct irq_desc *desc)
{
struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
+ struct irq_chip *chip = irq_desc_get_chip(desc);
void __iomem *claim = handler->hart_base + CONTEXT_CLAIM;
irq_hw_number_t hwirq;
WARN_ON_ONCE(!handler->present);
- csr_clear(CSR_IE, IE_EIE);
+ chained_irq_enter(chip, desc);
+
while ((hwirq = readl(claim))) {
int irq = irq_find_mapping(plic_irqdomain, hwirq);
@@ -213,7 +218,23 @@ static void plic_handle_irq(struct pt_regs *regs)
else
generic_handle_irq(irq);
}
- csr_set(CSR_IE, IE_EIE);
+
+ chained_irq_exit(chip, desc);
+}
+
+static int plic_cpu_starting(unsigned int cpu)
+{
+ if (plic_parent_irq)
+ enable_percpu_irq(plic_parent_irq,
+ irq_get_trigger_type(plic_parent_irq));
+ return 0;
+}
+
+static int plic_cpu_dying(unsigned int cpu)
+{
+ if (plic_parent_irq)
+ disable_percpu_irq(plic_parent_irq);
+ return 0;
}
/*
@@ -281,6 +302,13 @@ static int __init plic_init(struct device_node *node,
if (parent.args[0] != RV_IRQ_EXT)
continue;
+ if (irq_find_host(parent.np)) {
+ plic_parent_irq = irq_of_parse_and_map(node, i);
+ if (plic_parent_irq)
+ irq_set_chained_handler(plic_parent_irq,
+ plic_handle_irq);
+ }
+
hartid = plic_find_hart_id(parent.np);
if (hartid < 0) {
pr_warn("failed to parse hart ID for context %d.\n", i);
@@ -320,9 +348,12 @@ static int __init plic_init(struct device_node *node,
nr_handlers++;
}
+ cpuhp_setup_state(CPUHP_AP_IRQ_PLIC_STARTING,
+ "irqchip/sifive/plic:starting",
+ plic_cpu_starting, plic_cpu_dying);
+
pr_info("mapped %d interrupts with %d handlers for %d contexts.\n",
nr_irqs, nr_handlers, nr_contexts);
- set_handle_irq(plic_handle_irq);
return 0;
out_iounmap:
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index d37c17e68268..133baff276d0 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -102,6 +102,8 @@ enum cpuhp_state {
CPUHP_AP_IRQ_ARMADA_XP_STARTING,
CPUHP_AP_IRQ_BCM2836_STARTING,
CPUHP_AP_IRQ_MIPS_GIC_STARTING,
+ CPUHP_AP_IRQ_RISCV_STARTING,
+ CPUHP_AP_IRQ_PLIC_STARTING,
CPUHP_AP_ARM_MVEBU_COHERENCY,
CPUHP_AP_MICROCODE_LOADER,
CPUHP_AP_PERF_X86_AMD_UNCORE_STARTING,
--
2.17.1