From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B2C0C636CD for ; Sun, 5 Feb 2023 11:30:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229654AbjBELaR (ORCPT ); Sun, 5 Feb 2023 06:30:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39018 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229604AbjBEL37 (ORCPT ); Sun, 5 Feb 2023 06:29:59 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32E071A49D for ; Sun, 5 Feb 2023 03:29:58 -0800 (PST) Date: Sun, 05 Feb 2023 11:29:54 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1675596594; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1BJ78ZEelCzpc4Lc9YVZG0Euqu42pu8LhXEZqrUB7Ns=; b=Rasqx7Sxp3/GIb1lYBsexPs3s9q4eme/Q2h+BWhkTfXhq1qy4dGfEANF7Yf9454F0QJNrI AfyozrZOoHmKuXBmTUMjpUj9mZs/xJQEjvTma3G85RjyY53wgvg2H1NJ1Kp0hzSh/w37Kt wTfby3DbrLH2xP5m3GssWurE/aKLMOUDPPeoYbnIEhREEFk0UnXYpQjDVlHroed6MM1Mjs UNNOseo2h9NltFTJJW34qX1dO8afeNzHyIGulZ/HjyXFhtJa0NRBmXjiOI7z6JEE6ZQIKB 9JbEZsSIYu5YtqOYeetxUtP6j2I47+wzhjCQ3hmkS0K7FCsLdnCDxFEDy8VHXg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1675596594; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1BJ78ZEelCzpc4Lc9YVZG0Euqu42pu8LhXEZqrUB7Ns=; b=7HAsYgZrRw/0t35liYSeE18iINgjk+OckppEGy17a3A/sL5fEqf+pEjO+4w6yszcMId4vF OJMA7/qLUndrA6Bg== From: "irqchip-bot for Anup Patel" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-kernel@vger.kernel.org Subject: [irqchip: irq/irqchip-next] genirq: Add mechanism to multiplex a single HW IPI Cc: Anup Patel , Hector Martin , Marc Zyngier , tglx@linutronix.de In-Reply-To: <20230103141221.772261-4-apatel@ventanamicro.com> References: <20230103141221.772261-4-apatel@ventanamicro.com> MIME-Version: 1.0 Message-ID: <167559659451.4906.16474383879130890178.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the irq/irqchip-next branch of irqchip: Commit-ID: 835a486cd9f55790dee9f6b67ce0057d49f15da5 Gitweb: https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/835a486cd9f55790dee9f6b67ce0057d49f15da5 Author: Anup Patel AuthorDate: Tue, 03 Jan 2023 19:42:15 +05:30 Committer: Marc Zyngier CommitterDate: Sun, 05 Feb 2023 10:57:55 genirq: Add mechanism to multiplex a single HW IPI All RISC-V platforms have a single HW IPI provided by the INTC local interrupt controller. The HW method to trigger INTC IPI can be through external irqchip (e.g. RISC-V AIA), through platform specific device (e.g. SiFive CLINT timer), or through firmware (e.g. SBI IPI call). To support multiple IPIs on RISC-V, add a generic IPI multiplexing mechanism which help us create multiple virtual IPIs using a single HW IPI. This generic IPI multiplexing is inspired by the Apple AIC irqchip driver and it is shared by various RISC-V irqchip drivers. Signed-off-by: Anup Patel Reviewed-by: Hector Martin Tested-by: Hector Martin Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230103141221.772261-4-apatel@ventanamicro.com --- include/linux/irq.h | 3 +- kernel/irq/Kconfig | 5 +- kernel/irq/Makefile | 1 +- kernel/irq/ipi-mux.c | 207 ++++++++++++++++++++++++++++++++++++++++++- 4 files changed, 216 insertions(+) create mode 100644 kernel/irq/ipi-mux.c diff --git a/include/linux/irq.h b/include/linux/irq.h index c3eb896..b1b28af 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -1266,6 +1266,9 @@ int __ipi_send_mask(struct irq_desc *desc, const struct cpumask *dest); int ipi_send_single(unsigned int virq, unsigned int cpu); int ipi_send_mask(unsigned int virq, const struct cpumask *dest); +void ipi_mux_process(void); +int ipi_mux_create(unsigned int nr_ipi, void (*mux_send)(unsigned int cpu)); + #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER /* * Registers a generic IRQ handling function as the top-level IRQ handler in diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig index b64c44a..2531f34 100644 --- a/kernel/irq/Kconfig +++ b/kernel/irq/Kconfig @@ -86,6 +86,11 @@ config GENERIC_IRQ_IPI depends on SMP select IRQ_DOMAIN_HIERARCHY +# Generic IRQ IPI Mux support +config GENERIC_IRQ_IPI_MUX + bool + depends on SMP + # Generic MSI hierarchical interrupt domain support config GENERIC_MSI_IRQ bool diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile index b4f5371..f19d308 100644 --- a/kernel/irq/Makefile +++ b/kernel/irq/Makefile @@ -15,6 +15,7 @@ obj-$(CONFIG_GENERIC_IRQ_MIGRATION) += cpuhotplug.o obj-$(CONFIG_PM_SLEEP) += pm.o obj-$(CONFIG_GENERIC_MSI_IRQ) += msi.o obj-$(CONFIG_GENERIC_IRQ_IPI) += ipi.o +obj-$(CONFIG_GENERIC_IRQ_IPI_MUX) += ipi-mux.o obj-$(CONFIG_SMP) += affinity.o obj-$(CONFIG_GENERIC_IRQ_DEBUGFS) += debugfs.o obj-$(CONFIG_GENERIC_IRQ_MATRIX_ALLOCATOR) += matrix.o diff --git a/kernel/irq/ipi-mux.c b/kernel/irq/ipi-mux.c new file mode 100644 index 0000000..3a403c3 --- /dev/null +++ b/kernel/irq/ipi-mux.c @@ -0,0 +1,207 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Multiplex several virtual IPIs over a single HW IPI. + * + * Copyright The Asahi Linux Contributors + * Copyright (c) 2022 Ventana Micro Systems Inc. + */ + +#define pr_fmt(fmt) "ipi-mux: " fmt +#include +#include +#include +#include +#include +#include +#include +#include +#include + +struct ipi_mux_cpu { + atomic_t enable; + atomic_t bits; +}; + +static struct ipi_mux_cpu __percpu *ipi_mux_pcpu; +static struct irq_domain *ipi_mux_domain; +static void (*ipi_mux_send)(unsigned int cpu); + +static void ipi_mux_mask(struct irq_data *d) +{ + struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu); + + atomic_andnot(BIT(irqd_to_hwirq(d)), &icpu->enable); +} + +static void ipi_mux_unmask(struct irq_data *d) +{ + struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu); + u32 ibit = BIT(irqd_to_hwirq(d)); + + atomic_or(ibit, &icpu->enable); + + /* + * The atomic_or() above must complete before the atomic_read() + * below to avoid racing ipi_mux_send_mask(). + */ + smp_mb__after_atomic(); + + /* If a pending IPI was unmasked, raise a parent IPI immediately. */ + if (atomic_read(&icpu->bits) & ibit) + ipi_mux_send(smp_processor_id()); +} + +static void ipi_mux_send_mask(struct irq_data *d, const struct cpumask *mask) +{ + struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu); + u32 ibit = BIT(irqd_to_hwirq(d)); + unsigned long pending; + int cpu; + + for_each_cpu(cpu, mask) { + icpu = per_cpu_ptr(ipi_mux_pcpu, cpu); + + /* + * This sequence is the mirror of the one in ipi_mux_unmask(); + * see the comment there. Additionally, release semantics + * ensure that the vIPI flag set is ordered after any shared + * memory accesses that precede it. This therefore also pairs + * with the atomic_fetch_andnot in ipi_mux_process(). + */ + pending = atomic_fetch_or_release(ibit, &icpu->bits); + + /* + * The atomic_fetch_or_release() above must complete + * before the atomic_read() below to avoid racing with + * ipi_mux_unmask(). + */ + smp_mb__after_atomic(); + + /* + * The flag writes must complete before the physical IPI is + * issued to another CPU. This is implied by the control + * dependency on the result of atomic_read() below, which is + * itself already ordered after the vIPI flag write. + */ + if (!(pending & ibit) && (atomic_read(&icpu->enable) & ibit)) + ipi_mux_send(cpu); + } +} + +static const struct irq_chip ipi_mux_chip = { + .name = "IPI Mux", + .irq_mask = ipi_mux_mask, + .irq_unmask = ipi_mux_unmask, + .ipi_send_mask = ipi_mux_send_mask, +}; + +static int ipi_mux_domain_alloc(struct irq_domain *d, unsigned int virq, + unsigned int nr_irqs, void *arg) +{ + int i; + + for (i = 0; i < nr_irqs; i++) { + irq_set_percpu_devid(virq + i); + irq_domain_set_info(d, virq + i, i, &ipi_mux_chip, NULL, + handle_percpu_devid_irq, NULL, NULL); + } + + return 0; +} + +static const struct irq_domain_ops ipi_mux_domain_ops = { + .alloc = ipi_mux_domain_alloc, + .free = irq_domain_free_irqs_top, +}; + +/** + * ipi_mux_process - Process multiplexed virtual IPIs + */ +void ipi_mux_process(void) +{ + struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu); + irq_hw_number_t hwirq; + unsigned long ipis; + unsigned int en; + + /* + * Reading enable mask does not need to be ordered as long as + * this function is called from interrupt handler because only + * the CPU itself can change it's own enable mask. + */ + en = atomic_read(&icpu->enable); + + /* + * Clear the IPIs we are about to handle. This pairs with the + * atomic_fetch_or_release() in ipi_mux_send_mask(). + */ + ipis = atomic_fetch_andnot(en, &icpu->bits) & en; + + for_each_set_bit(hwirq, &ipis, BITS_PER_TYPE(int)) + generic_handle_domain_irq(ipi_mux_domain, hwirq); +} + +/** + * ipi_mux_create - Create virtual IPIs multiplexed on top of a single + * parent IPI. + * @nr_ipi: number of virtual IPIs to create. This should + * be <= BITS_PER_TYPE(int) + * @mux_send: callback to trigger parent IPI for a particular CPU + * + * Returns first virq of the newly created virtual IPIs upon success + * or <=0 upon failure + */ +int ipi_mux_create(unsigned int nr_ipi, void (*mux_send)(unsigned int cpu)) +{ + struct fwnode_handle *fwnode; + struct irq_domain *domain; + int rc; + + if (ipi_mux_domain) + return -EEXIST; + + if (BITS_PER_TYPE(int) < nr_ipi || !mux_send) + return -EINVAL; + + ipi_mux_pcpu = alloc_percpu(typeof(*ipi_mux_pcpu)); + if (!ipi_mux_pcpu) + return -ENOMEM; + + fwnode = irq_domain_alloc_named_fwnode("IPI-Mux"); + if (!fwnode) { + pr_err("unable to create IPI Mux fwnode\n"); + rc = -ENOMEM; + goto fail_free_cpu; + } + + domain = irq_domain_create_linear(fwnode, nr_ipi, + &ipi_mux_domain_ops, NULL); + if (!domain) { + pr_err("unable to add IPI Mux domain\n"); + rc = -ENOMEM; + goto fail_free_fwnode; + } + + domain->flags |= IRQ_DOMAIN_FLAG_IPI_SINGLE; + irq_domain_update_bus_token(domain, DOMAIN_BUS_IPI); + + rc = __irq_domain_alloc_irqs(domain, -1, nr_ipi, + NUMA_NO_NODE, NULL, false, NULL); + if (rc <= 0) { + pr_err("unable to alloc IRQs from IPI Mux domain\n"); + goto fail_free_domain; + } + + ipi_mux_domain = domain; + ipi_mux_send = mux_send; + + return rc; + +fail_free_domain: + irq_domain_remove(domain); +fail_free_fwnode: + irq_domain_free_fwnode(fwnode); +fail_free_cpu: + free_percpu(ipi_mux_pcpu); + return rc; +}