This patch adds a driver for the Platform Level Interrupt Controller (PLIC) specified as part of the RISC-V supervisor level ISA manual. The PLIC connocts global interrupt sources to the local interrupt controller on each hart. A PLIC is present on all RISC-V systems. Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxx> --- drivers/irqchip/Kconfig | 13 ++ drivers/irqchip/Makefile | 1 + drivers/irqchip/irq-riscv-plic.c | 379 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 393 insertions(+) create mode 100644 drivers/irqchip/irq-riscv-plic.c diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig index 7923d3fa8fae..c23539923c10 100644 --- a/drivers/irqchip/Kconfig +++ b/drivers/irqchip/Kconfig @@ -307,6 +307,19 @@ config QCOM_IRQ_COMBINER Say yes here to add support for the IRQ combiner devices embedded in Qualcomm Technologies chips. +config RISCV_PLIC + bool "Platform-Level Interrupt Controller" + depends on RISCV + default y + help + This enables support for the PLIC chip found in standard 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 (MSI, GPIO, etc) + are subordinate to the PLIC. + + If you don't know what to do here, say Y. + config RISCV_INTC def_bool y if RISCV #bool "RISC-V Interrupt Controller" diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile index b1aa9114afc4..7880c9cec40e 100644 --- a/drivers/irqchip/Makefile +++ b/drivers/irqchip/Makefile @@ -78,4 +78,5 @@ obj-$(CONFIG_EZNPS_GIC) += irq-eznps.o obj-$(CONFIG_ARCH_ASPEED) += irq-aspeed-vic.o irq-aspeed-i2c-ic.o obj-$(CONFIG_STM32_EXTI) += irq-stm32-exti.o obj-$(CONFIG_QCOM_IRQ_COMBINER) += qcom-irq-combiner.o +obj-$(CONFIG_RISCV_PLIC) += irq-riscv-plic.o obj-$(CONFIG_RISCV_INTC) += irq-riscv-intc.o diff --git a/drivers/irqchip/irq-riscv-plic.c b/drivers/irqchip/irq-riscv-plic.c new file mode 100644 index 000000000000..b5182b43b377 --- /dev/null +++ b/drivers/irqchip/irq-riscv-plic.c @@ -0,0 +1,379 @@ +/* + * Copyright (C) 2017 SiFive + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#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> +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/platform_device.h> +#include <linux/spinlock.h> + +/* + * From the RISC-V Privlidged Spec v1.10: + * + * Global interrupt sources are assigned small unsigned integer identifiers, + * beginning at the value 1. An interrupt ID of 0 is reserved to mean “no + * interrupt”. Interrupt identifiers are also used to break ties when two or + * more interrupt sources have the same assigned priority. Smaller values of + * interrupt ID take precedence over larger values of interrupt ID. + * + * While the RISC-V supervisor spec doesn't define the maximum number of + * devices supported by the PLIC, the largest number supported by devices + * marked as 'riscv,plic0' (which is the only device type this driver supports, + * and is the only extant PLIC as of now) is 1024. As mentioned above, device + * 0 is defined to be non-existant so this device really only supports 1023 + * devices. + */ +#define MAX_DEVICES 1024 +#define MAX_CONTEXTS 15872 + +/* + * The PLIC consists of memory-mapped control registers, with a memory map as + * follows: + * + * base + 0x000000: Reserved (interrupt source 0 does not exist) + * base + 0x000004: Interrupt source 1 priority + * base + 0x000008: Interrupt source 2 priority + * ... + * base + 0x000FFC: Interrupt source 1023 priority + * base + 0x001000: Pending 0 + * base + 0x001FFF: Pending + * base + 0x002000: Enable bits for sources 0-31 on context 0 + * base + 0x002004: Enable bits for sources 32-63 on context 0 + * ... + * base + 0x0020FC: Enable bits for sources 992-1023 on context 0 + * base + 0x002080: Enable bits for sources 0-31 on context 1 + * ... + * base + 0x002100: Enable bits for sources 0-31 on context 2 + * ... + * base + 0x1F1F80: Enable bits for sources 992-1023 on context 15871 + * base + 0x1F1F84: Reserved + * ... (higher context IDs would fit here, but wouldn't fit + * inside the per-context priority vector) + * base + 0x1FFFFC: Reserved + * base + 0x200000: Priority threshold for context 0 + * base + 0x200004: Claim/complete for context 0 + * base + 0x200008: Reserved + * ... + * base + 0x200FFC: Reserved + * base + 0x201000: Priority threshold for context 1 + * base + 0x201004: Claim/complete for context 1 + * ... + * base + 0xFFE000: Priority threshold for context 15871 + * base + 0xFFE004: Claim/complete for context 15871 + * base + 0xFFE008: Reserved + * ... + * base + 0xFFFFFC: Reserved + */ + +/* Each interrupt source has a priority register associated with it. */ +#define PRIORITY_BASE 0 +#define PRIORITY_PER_ID 4 + +/* + * Each hart context has a vector of interupt 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 0 +#define CONTEXT_CLAIM 4 + +/* + * PLIC devices are named like 'riscv,plic0,%llx', this is enough space to + * store that name. + */ +#define PLIC_DATA_NAME_SIZE 30 + +struct plic_handler { + bool present; + int contextid; + struct plic_data *data; +}; + +struct plic_data { + struct irq_chip chip; + struct irq_domain *domain; + u32 ndev; + void __iomem *reg; + int handlers; + struct plic_handler *handler; + char name[PLIC_DATA_NAME_SIZE]; + spinlock_t lock; +}; + +/* Addressing helper functions. */ +static inline +void __iomem *plic_enable_vector(struct plic_data *data, int contextid) +{ + return data->reg + ENABLE_BASE + contextid * ENABLE_PER_HART; +} + +static inline +void __iomem *plic_priority(struct plic_data *data, int hwirq) +{ + return data->reg + PRIORITY_BASE + hwirq * PRIORITY_PER_ID; +} + +static inline +void __iomem *plic_hart_threshold(struct plic_data *data, int contextid) +{ + return data->reg + CONTEXT_BASE + CONTEXT_PER_HART * contextid + CONTEXT_THRESHOLD; +} + +static inline +void __iomem *plic_hart_claim(struct plic_data *data, int contextid) +{ + return data->reg + CONTEXT_BASE + CONTEXT_PER_HART * contextid + CONTEXT_CLAIM; +} + +/* + * 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 inline +u32 plic_claim(struct plic_data *data, int contextid) +{ + return readl(plic_hart_claim(data, contextid)); +} + +static inline +void plic_complete(struct plic_data *data, int contextid, u32 claim) +{ + writel(claim, plic_hart_claim(data, contextid)); +} + +/* Explicit interrupt masking. */ +static void plic_disable(struct plic_data *data, int contextid, int hwirq) +{ + void __iomem *reg = plic_enable_vector(data, contextid) + (hwirq / 32); + u32 mask = ~(1 << (hwirq % 32)); + + spin_lock(&data->lock); + writel(readl(reg) & mask, reg); + spin_unlock(&data->lock); +} + +static void plic_enable(struct plic_data *data, int contextid, int hwirq) +{ + void __iomem *reg = plic_enable_vector(data, contextid) + (hwirq / 32); + u32 bit = 1 << (hwirq % 32); + + spin_lock(&data->lock); + writel(readl(reg) | bit, reg); + spin_unlock(&data->lock); +} + +/* + * There is no need to mask/unmask PLIC interrupts + * They are "masked" by reading claim and "unmasked" when writing it back. + */ +static void plic_irq_mask(struct irq_data *d) { } +static void plic_irq_unmask(struct irq_data *d) { } + +static void plic_irq_enable(struct irq_data *d) +{ + struct plic_data *data = irq_data_get_irq_chip_data(d); + void __iomem *priority = plic_priority(data, d->hwirq); + int i; + + writel(1, priority); + for (i = 0; i < data->handlers; ++i) + if (data->handler[i].present) + plic_enable(data, i, d->hwirq); +} + +static void plic_irq_disable(struct irq_data *d) +{ + struct plic_data *data = irq_data_get_irq_chip_data(d); + void __iomem *priority = plic_priority(data, d->hwirq); + int i; + + writel(0, priority); + for (i = 0; i < data->handlers; ++i) + if (data->handler[i].present) + plic_disable(data, i, d->hwirq); +} + +static void plic_irq_eoi(struct irq_data *d) +{ + /* FIXME: I can't figure out what's going on here: when I set the PLIC + * driver to use hadle_fasteoi_irq I end up with !handler here. The + * difference is that here we get an irq_data and use + * common.handler_data, while in the working version we get an + * irq_desc and use irq_common_data.handler_data. */ + struct plic_handler *handler = d->common->handler_data; + BUG_ON(!handler); + plic_complete(handler->data, handler->contextid, d->hwirq); +} + +static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq, + irq_hw_number_t hwirq) +{ + struct plic_data *data = d->host_data; + + /* FIXME: ... I want to set handle_fasteoi_irq here. */ + irq_set_chip_and_handler(irq, &data->chip, handle_simple_irq); + irq_set_chip_data(irq, data); + 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 void plic_chained_handle_irq(struct irq_desc *desc) +{ + struct plic_handler *handler = irq_desc_get_handler_data(desc); + struct irq_chip *chip = irq_desc_get_chip(desc); + struct irq_domain *domain = handler->data->domain; + u32 what; + + chained_irq_enter(chip, desc); + + while ((what = plic_claim(handler->data, handler->contextid))) { + int irq = irq_find_mapping(domain, what); + + if (irq > 0) + generic_handle_irq(irq); + else + handle_bad_irq(desc); + plic_complete(handler->data, handler->contextid, what); + } + + chained_irq_exit(chip, desc); +} + +static int plic_init(struct device_node *node, struct device_node *parent) +{ + struct plic_data *data; + struct resource resource; + int i, ok = 0; + int out = -1; + + data = kzalloc(sizeof(*data), GFP_KERNEL); + if (WARN_ON(!data)) + return -ENOMEM; + + spin_lock_init(&data->lock); + + data->reg = of_iomap(node, 0); + if (WARN_ON(!data->reg)) { + out = -EIO; + goto free_data; + } + + of_property_read_u32(node, "riscv,ndev", &data->ndev); + if (WARN_ON(!data->ndev)) { + out = -EINVAL; + goto free_reg; + } + + data->handlers = of_irq_count(node); + if (WARN_ON(!data->handlers)) { + out = -EINVAL; + goto free_reg; + } + + data->handler = + kcalloc(data->handlers, sizeof(*data->handler), GFP_KERNEL); + if (WARN_ON(!data->handler)) { + out = -ENOMEM; + goto free_reg; + } + + data->domain = irq_domain_add_linear(node, data->ndev+1, &plic_irqdomain_ops, data); + if (WARN_ON(!data->domain)) { + out = -ENOMEM; + goto free_handler; + } + + of_address_to_resource(node, 0, &resource); + snprintf(data->name, sizeof(data->name), + "riscv,plic0,%llx", resource.start); + data->chip.name = data->name; + data->chip.irq_mask = plic_irq_mask; + data->chip.irq_unmask = plic_irq_unmask; + data->chip.irq_enable = plic_irq_enable; + data->chip.irq_disable = plic_irq_disable; + data->chip.irq_eoi = plic_irq_eoi; + + for (i = 0; i < data->handlers; ++i) { + struct plic_handler *handler = &data->handler[i]; + struct of_phandle_args parent; + int parent_irq, hwirq; + + handler->present = false; + + if (of_irq_parse_one(node, i, &parent)) + continue; + /* skip context holes */ + if (parent.args[0] == -1) + continue; + + /* skip any contexts that lead to inactive harts */ + if (of_device_is_compatible(parent.np, "riscv,cpu-intc") && + parent.np->parent && + riscv_of_processor_hart(parent.np->parent) < 0) + continue; + + parent_irq = irq_create_of_mapping(&parent); + if (!parent_irq) + continue; + + handler->present = true; + handler->contextid = i; + handler->data = data; + /* hwirq prio must be > this to trigger an interrupt */ + writel(0, plic_hart_threshold(data, i)); + + for (hwirq = 1; hwirq <= data->ndev; ++hwirq) + plic_disable(data, i, hwirq); + irq_set_chained_handler_and_data(parent_irq, plic_chained_handle_irq, handler); + ++ok; + } + + pr_info("%s: mapped %d interrupts to %d/%d handlers\n", + data->name, data->ndev, ok, data->handlers); + WARN_ON(!ok); + return 0; + +free_handler: + kfree(data->handler); +free_reg: + iounmap(data->reg); +free_data: + kfree(data); + return out; +} + +IRQCHIP_DECLARE(plic0, "riscv,plic0", plic_init); -- 2.13.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html