We've unfortunately started seeing a situation where percpu interrupts are partitioned in the system: one arbitrary set of CPUs has an interrupt connected to a type of device, while another disjoint set of CPUs has the same interrupt connected to another type of device. This makes it impossible to have a device driver requesting this interrupt using the current percpu-interrupt abstraction, as the same interrupt number is now potentially claimed by at least two drivers, and we forbid interrupt sharing on per-cpu interrupt. A solution to this is to turn things upside down. Let's assume that our system describes all the possible partitions for a given interrupt, and give each of them a unique identifier. It is then possible to create a namespace where the affinity identifier itself is a form of interrupt number. At this point, it becomes easy to implement a set of partitions as a cascaded irqchip, each affinity identifier being the HW irq. This allows us to keep a number of nice properties: - Each partition results in a separate percpu-interrupt (with a restrictied affinity), which keeps drivers happy. - Because the underlying interrupt is still per-cpu, the overhead of the indirection can be kept pretty minimal. - The core code can ignore most of that crap. For that purpose, we implement a small library that deals with some of the boilerplate code, relying on platform-specific drivers to provide a description of the affinity sets and a set of callbacks. Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> --- drivers/irqchip/Kconfig | 3 + drivers/irqchip/Makefile | 1 + drivers/irqchip/irq-partition-percpu.c | 256 +++++++++++++++++++++++++++ include/linux/irqchip/irq-partition-percpu.h | 59 ++++++ 4 files changed, 319 insertions(+) create mode 100644 drivers/irqchip/irq-partition-percpu.c create mode 100644 include/linux/irqchip/irq-partition-percpu.h diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig index 3e12479..ea1836b 100644 --- a/drivers/irqchip/Kconfig +++ b/drivers/irqchip/Kconfig @@ -244,3 +244,6 @@ config IRQ_MXS config MVEBU_ODMI bool select GENERIC_MSI_IRQ_DOMAIN + +config PARTITION_PERCPU + bool diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile index b03cfcb..e354b00c 100644 --- a/drivers/irqchip/Makefile +++ b/drivers/irqchip/Makefile @@ -27,6 +27,7 @@ obj-$(CONFIG_REALVIEW_DT) += irq-gic-realview.o obj-$(CONFIG_ARM_GIC_V2M) += irq-gic-v2m.o obj-$(CONFIG_ARM_GIC_V3) += irq-gic-v3.o irq-gic-common.o obj-$(CONFIG_ARM_GIC_V3_ITS) += irq-gic-v3-its.o irq-gic-v3-its-pci-msi.o irq-gic-v3-its-platform-msi.o +obj-$(CONFIG_PARTITION_PERCPU) += irq-partition-percpu.o obj-$(CONFIG_HISILICON_IRQ_MBIGEN) += irq-mbigen.o obj-$(CONFIG_ARM_NVIC) += irq-nvic.o obj-$(CONFIG_ARM_VIC) += irq-vic.o diff --git a/drivers/irqchip/irq-partition-percpu.c b/drivers/irqchip/irq-partition-percpu.c new file mode 100644 index 0000000..ccd72c2 --- /dev/null +++ b/drivers/irqchip/irq-partition-percpu.c @@ -0,0 +1,256 @@ +/* + * Copyright (C) 2016 ARM Limited, All Rights Reserved. + * Author: Marc Zyngier <marc.zyngier@xxxxxxx> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/bitops.h> +#include <linux/interrupt.h> +#include <linux/irqchip.h> +#include <linux/irqchip/chained_irq.h> +#include <linux/irqchip/irq-partition-percpu.h> +#include <linux/irqdomain.h> +#include <linux/seq_file.h> +#include <linux/slab.h> + +struct partition_desc { + int nr_parts; + struct partition_affinity *parts; + struct irq_domain *domain; + struct irq_desc *chained_desc; + unsigned long *bitmap; + struct irq_domain_ops ops; +}; + +static bool partition_check_cpu(struct partition_desc *part, + unsigned int cpu, unsigned int hwirq) +{ + return cpumask_test_cpu(cpu, &part->parts[hwirq].mask); +} + +static void partition_irq_mask(struct irq_data *d) +{ + struct partition_desc *part = irq_data_get_irq_chip_data(d); + struct irq_chip *chip = irq_desc_get_chip(part->chained_desc); + struct irq_data *data = irq_desc_get_irq_data(part->chained_desc); + + if (partition_check_cpu(part, smp_processor_id(), d->hwirq) && + chip->irq_mask) + chip->irq_mask(data); +} + +static void partition_irq_unmask(struct irq_data *d) +{ + struct partition_desc *part = irq_data_get_irq_chip_data(d); + struct irq_chip *chip = irq_desc_get_chip(part->chained_desc); + struct irq_data *data = irq_desc_get_irq_data(part->chained_desc); + + if (partition_check_cpu(part, smp_processor_id(), d->hwirq) && + chip->irq_unmask) + chip->irq_unmask(data); +} + +static int partition_irq_set_irqchip_state(struct irq_data *d, + enum irqchip_irq_state which, + bool val) +{ + struct partition_desc *part = irq_data_get_irq_chip_data(d); + struct irq_chip *chip = irq_desc_get_chip(part->chained_desc); + struct irq_data *data = irq_desc_get_irq_data(part->chained_desc); + + if (partition_check_cpu(part, smp_processor_id(), d->hwirq) && + chip->irq_set_irqchip_state) + return chip->irq_set_irqchip_state(data, which, val); + + return -EINVAL; +} + +static int partition_irq_get_irqchip_state(struct irq_data *d, + enum irqchip_irq_state which, + bool *val) +{ + struct partition_desc *part = irq_data_get_irq_chip_data(d); + struct irq_chip *chip = irq_desc_get_chip(part->chained_desc); + struct irq_data *data = irq_desc_get_irq_data(part->chained_desc); + + if (partition_check_cpu(part, smp_processor_id(), d->hwirq) && + chip->irq_get_irqchip_state) + return chip->irq_get_irqchip_state(data, which, val); + + return -EINVAL; +} + +static int partition_irq_set_type(struct irq_data *d, unsigned int type) +{ + struct partition_desc *part = irq_data_get_irq_chip_data(d); + struct irq_chip *chip = irq_desc_get_chip(part->chained_desc); + struct irq_data *data = irq_desc_get_irq_data(part->chained_desc); + + if (chip->irq_set_type) + return chip->irq_set_type(data, type); + + return -EINVAL; +} + +static void partition_irq_print_chip(struct irq_data *d, struct seq_file *p) +{ + struct partition_desc *part = irq_data_get_irq_chip_data(d); + struct irq_chip *chip = irq_desc_get_chip(part->chained_desc); + struct irq_data *data = irq_desc_get_irq_data(part->chained_desc); + + seq_printf(p, " %5s-%lu", chip->name, data->hwirq); +} + +static struct irq_chip partition_irq_chip = { + .irq_mask = partition_irq_mask, + .irq_unmask = partition_irq_unmask, + .irq_set_type = partition_irq_set_type, + .irq_get_irqchip_state = partition_irq_get_irqchip_state, + .irq_set_irqchip_state = partition_irq_set_irqchip_state, + .irq_print_chip = partition_irq_print_chip, +}; + +static void partition_handle_irq(struct irq_desc *desc) +{ + struct partition_desc *part = irq_desc_get_handler_data(desc); + struct irq_chip *chip = irq_desc_get_chip(desc); + int cpu = smp_processor_id(); + int hwirq; + + chained_irq_enter(chip, desc); + + for_each_set_bit(hwirq, part->bitmap, part->nr_parts) { + if (partition_check_cpu(part, cpu, hwirq)) + break; + } + + if (unlikely(hwirq == part->nr_parts)) { + handle_bad_irq(desc); + } else { + unsigned int irq; + irq = irq_find_mapping(part->domain, hwirq); + generic_handle_irq(irq); + } + + chained_irq_exit(chip, desc); +} + +static int partition_domain_alloc(struct irq_domain *domain, unsigned int virq, + unsigned int nr_irqs, void *arg) +{ + int ret; + irq_hw_number_t hwirq; + unsigned int type; + struct irq_fwspec *fwspec = arg; + struct partition_desc *part; + + BUG_ON(nr_irqs != 1); + ret = domain->ops->translate(domain, fwspec, &hwirq, &type); + if (ret) + return ret; + + part = domain->host_data; + + set_bit(hwirq, part->bitmap); + irq_set_chained_handler_and_data(irq_desc_get_irq(part->chained_desc), + partition_handle_irq, part); + irq_set_percpu_devid_partition(virq, &part->parts[hwirq].mask); + irq_domain_set_info(domain, virq, hwirq, &partition_irq_chip, part, + handle_percpu_devid_irq, NULL, NULL); + irq_set_status_flags(virq, IRQ_NOAUTOEN); + + return 0; +} + +static void partition_domain_free(struct irq_domain *domain, unsigned int virq, + unsigned int nr_irqs) +{ + struct irq_data *d; + + BUG_ON(nr_irqs != 1); + + d = irq_domain_get_irq_data(domain, virq); + irq_set_handler(virq, NULL); + irq_domain_reset_irq_data(d); +} + +int partition_translate_id(struct partition_desc *desc, void *partition_id) +{ + struct partition_affinity *part = NULL; + int i; + + for (i = 0; i < desc->nr_parts; i++) { + if (desc->parts[i].partition_id == partition_id) { + part = &desc->parts[i]; + break; + } + } + + if (WARN_ON(!part)) { + pr_err("Failed to find partition\n"); + return -EINVAL; + } + + return i; +} + +struct partition_desc *partition_create_desc(struct fwnode_handle *fwnode, + struct partition_affinity *parts, + int nr_parts, + int chained_irq, + const struct irq_domain_ops *ops) +{ + struct partition_desc *desc; + struct irq_domain *d; + + BUG_ON(!ops->select || !ops->translate); + + desc = kzalloc(sizeof(*desc), GFP_KERNEL); + if (!desc) + return NULL; + + desc->ops = *ops; + desc->ops.free = partition_domain_free; + desc->ops.alloc = partition_domain_alloc; + + d = irq_domain_create_linear(fwnode, nr_parts, &desc->ops, desc); + if (!d) + goto out; + desc->domain = d; + + desc->bitmap = kzalloc(sizeof(long) * BITS_TO_LONGS(nr_parts), + GFP_KERNEL); + if (WARN_ON(!desc->bitmap)) + goto out; + + desc->chained_desc = irq_to_desc(chained_irq); + desc->nr_parts = nr_parts; + desc->parts = parts; + + return desc; +out: + if (d) + irq_domain_remove(d); + kfree(desc); + + return NULL; +} + +struct irq_domain *partition_get_domain(struct partition_desc *dsc) +{ + if (dsc) + return dsc->domain; + + return NULL; +} diff --git a/include/linux/irqchip/irq-partition-percpu.h b/include/linux/irqchip/irq-partition-percpu.h new file mode 100644 index 0000000..87433a5 --- /dev/null +++ b/include/linux/irqchip/irq-partition-percpu.h @@ -0,0 +1,59 @@ +/* + * Copyright (C) 2016 ARM Limited, All Rights Reserved. + * Author: Marc Zyngier <marc.zyngier@xxxxxxx> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/fwnode.h> +#include <linux/cpumask.h> +#include <linux/irqdomain.h> + +struct partition_affinity { + cpumask_t mask; + void *partition_id; +}; + +struct partition_desc; + +#ifdef CONFIG_PARTITION_PERCPU +int partition_translate_id(struct partition_desc *desc, void *partition_id); +struct partition_desc *partition_create_desc(struct fwnode_handle *fwnode, + struct partition_affinity *parts, + int nr_parts, + int chained_irq, + const struct irq_domain_ops *ops); +struct irq_domain *partition_get_domain(struct partition_desc *dsc); +#else +static inline int partition_translate_id(struct partition_desc *desc, + void *partition_id) +{ + return -EINVAL; +} + +static inline +struct partition_desc *partition_create_desc(struct fwnode_handle *fwnode, + struct partition_affinity *parts, + int nr_parts, + int chained_irq, + const struct irq_domain_ops *ops) +{ + return NULL; +} + +static inline +struct irq_domain *partition_get_domain(struct partition_desc *dsc) +{ + return NULL; +} +#endif -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
