diff options
Diffstat (limited to 'drivers/irqchip')
| -rw-r--r-- | drivers/irqchip/Kconfig | 12 | ||||
| -rw-r--r-- | drivers/irqchip/Makefile | 1 | ||||
| -rw-r--r-- | drivers/irqchip/irq-sifive-plic.c | 260 |
3 files changed, 273 insertions, 0 deletions
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig index e9233db16e03..df345b878ac2 100644 --- a/drivers/irqchip/Kconfig +++ b/drivers/irqchip/Kconfig @@ -372,3 +372,15 @@ config QCOM_PDC IRQs for Qualcomm Technologies Inc (QTI) mobile chips. endmenu + +config SIFIVE_PLIC + bool "SiFive Platform-Level Interrupt Controller" + depends on RISCV + help + This enables support for the PLIC chip found in SiFive (and + potentially other) RISC-V systems. The PLIC controls devices + interrupts and connects them to each core's local interrupt + controller. Aside from timer and software interrupts, all other + interrupt sources are subordinate to the PLIC. + + If you don't know what to do here, say Y. diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile index 15f268f646bf..fbd1ec8070ef 100644 --- a/drivers/irqchip/Makefile +++ b/drivers/irqchip/Makefile @@ -87,3 +87,4 @@ obj-$(CONFIG_MESON_IRQ_GPIO) += irq-meson-gpio.o obj-$(CONFIG_GOLDFISH_PIC) += irq-goldfish-pic.o obj-$(CONFIG_NDS32) += irq-ativic32.o obj-$(CONFIG_QCOM_PDC) += qcom-pdc.o +obj-$(CONFIG_SIFIVE_PLIC) += irq-sifive-plic.o diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c new file mode 100644 index 000000000000..532e9d68c704 --- /dev/null +++ b/drivers/irqchip/irq-sifive-plic.c @@ -0,0 +1,260 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2017 SiFive + * Copyright (C) 2018 Christoph Hellwig + */ +#define pr_fmt(fmt) "plic: " fmt +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/irq.h> +#include <linux/irqchip.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/platform_device.h> +#include <linux/spinlock.h> + +/* + * This driver implements a version of the RISC-V PLIC with the actual layout + * specified in chapter 8 of the SiFive U5 Coreplex Series Manual: + * + * https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf + * + * The largest number supported by devices marked as 'sifive,plic-1.0.0', is + * 1024, of which device 0 is defined as non-existent by the RISC-V Privileged + * Spec. + */ + +#define MAX_DEVICES 1024 +#define MAX_CONTEXTS 15872 + +/* + * Each interrupt source has a priority register associated with it. + * We always hardwire it to one in Linux. + */ +#define PRIORITY_BASE 0 +#define PRIORITY_PER_ID 4 + +/* + * Each hart context has a vector of interrupt enable bits associated with it. + * There's one bit for each interrupt source. + */ +#define ENABLE_BASE 0x2000 +#define ENABLE_PER_HART 0x80 + +/* + * Each hart context has a set of control registers associated with it. Right + * now there's only two: a source priority threshold over which the hart will + * take an interrupt, and a register to claim interrupts. + */ +#define CONTEXT_BASE 0x200000 +#define CONTEXT_PER_HART 0x1000 +#define CONTEXT_THRESHOLD 0x00 +#define CONTEXT_CLAIM 0x04 + +static void __iomem *plic_regs; + +struct plic_handler { + bool present; + int ctxid; +}; +static DEFINE_PER_CPU(struct plic_handler, plic_handlers); + +static inline void __iomem *plic_hart_offset(int ctxid) +{ + return plic_regs + CONTEXT_BASE + ctxid * CONTEXT_PER_HART; +} + +static inline u32 __iomem *plic_enable_base(int ctxid) +{ + return plic_regs + ENABLE_BASE + ctxid * ENABLE_PER_HART; +} + +/* + * Protect mask operations on the registers given that we can't assume that + * atomic memory operations work on them. + */ +static DEFINE_RAW_SPINLOCK(plic_toggle_lock); + +static inline void plic_toggle(int ctxid, int hwirq, int enable) +{ + u32 __iomem *reg = plic_enable_base(ctxid) + (hwirq / 32); + u32 hwirq_mask = 1 << (hwirq % 32); + + raw_spin_lock(&plic_toggle_lock); + if (enable) + writel(readl(reg) | hwirq_mask, reg); + else + writel(readl(reg) & ~hwirq_mask, reg); + raw_spin_unlock(&plic_toggle_lock); +} + +static inline void plic_irq_toggle(struct irq_data *d, int enable) +{ + int cpu; + + writel(enable, plic_regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID); + for_each_cpu(cpu, irq_data_get_affinity_mask(d)) { + struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu); + + if (handler->present) + plic_toggle(handler->ctxid, d->hwirq, enable); + } +} + +static void plic_irq_enable(struct irq_data *d) +{ + plic_irq_toggle(d, 1); +} + +static void plic_irq_disable(struct irq_data *d) +{ + plic_irq_toggle(d, 0); +} + +static struct irq_chip plic_chip = { + .name = "SiFive PLIC", + /* + * There is no need to mask/unmask PLIC interrupts. They are "masked" + * by reading claim and "unmasked" when writing it back. + */ + .irq_enable = plic_irq_enable, + .irq_disable = plic_irq_disable, +}; + +static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq, + irq_hw_number_t hwirq) +{ + irq_set_chip_and_handler(irq, &plic_chip, handle_simple_irq); + irq_set_chip_data(irq, NULL); + irq_set_noprobe(irq); + return 0; +} + +static const struct irq_domain_ops plic_irqdomain_ops = { + .map = plic_irqdomain_map, + .xlate = irq_domain_xlate_onecell, +}; + +static struct irq_domain *plic_irqdomain; + +/* + * Handling an interrupt is a two-step process: first you claim the interrupt + * by reading the claim register, then you complete the interrupt by writing + * 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) +{ + struct plic_handler *handler = this_cpu_ptr(&plic_handlers); + void __iomem *claim = plic_hart_offset(handler->ctxid) + CONTEXT_CLAIM; + irq_hw_number_t hwirq; + + WARN_ON_ONCE(!handler->present); + + csr_clear(sie, SIE_SEIE); + while ((hwirq = readl(claim))) { + int irq = irq_find_mapping(plic_irqdomain, hwirq); + + if (unlikely(irq <= 0)) + pr_warn_ratelimited("can't find mapping for hwirq %lu\n", + hwirq); + else + generic_handle_irq(irq); + writel(hwirq, claim); + } + csr_set(sie, SIE_SEIE); +} + +/* + * Walk up the DT tree until we find an active RISC-V core (HART) node and + * extract the cpuid from it. + */ +static int plic_find_hart_id(struct device_node *node) +{ + for (; node; node = node->parent) { + if (of_device_is_compatible(node, "riscv")) + return riscv_of_processor_hart(node); + } + + return -1; +} + +static int __init plic_init(struct device_node *node, + struct device_node *parent) +{ + int error = 0, nr_handlers, nr_mapped = 0, i; + u32 nr_irqs; + + if (plic_regs) { + pr_warn("PLIC already present.\n"); + return -ENXIO; + } + + plic_regs = of_iomap(node, 0); + if (WARN_ON(!plic_regs)) + return -EIO; + + error = -EINVAL; + of_property_read_u32(node, "riscv,ndev", &nr_irqs); + if (WARN_ON(!nr_irqs)) + goto out_iounmap; + + nr_handlers = of_irq_count(node); + if (WARN_ON(!nr_handlers)) + goto out_iounmap; + if (WARN_ON(nr_handlers < num_possible_cpus())) + goto out_iounmap; + + error = -ENOMEM; + plic_irqdomain = irq_domain_add_linear(node, nr_irqs + 1, + &plic_irqdomain_ops, NULL); + if (WARN_ON(!plic_irqdomain)) + goto out_iounmap; + + for (i = 0; i < nr_handlers; i++) { + struct of_phandle_args parent; + struct plic_handler *handler; + irq_hw_number_t hwirq; + int cpu; + + if (of_irq_parse_one(node, i, &parent)) { + pr_err("failed to parse parent for context %d.\n", i); + continue; + } + + /* skip context holes */ + if (parent.args[0] == -1) + continue; + + cpu = plic_find_hart_id(parent.np); + if (cpu < 0) { + pr_warn("failed to parse hart ID for context %d.\n", i); + continue; + } + + handler = per_cpu_ptr(&plic_handlers, cpu); + handler->present = true; + handler->ctxid = i; + + /* priority must be > threshold to trigger an interrupt */ + writel(0, plic_hart_offset(i) + CONTEXT_THRESHOLD); + for (hwirq = 1; hwirq <= nr_irqs; hwirq++) + plic_toggle(i, hwirq, 0); + nr_mapped++; + } + + pr_info("mapped %d interrupts to %d (out of %d) handlers.\n", + nr_irqs, nr_mapped, nr_handlers); + set_handle_irq(plic_handle_irq); + return 0; + +out_iounmap: + iounmap(plic_regs); + return error; +} + +IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init); +IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */ |