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Date: Fri, 21 Feb 2020 11:44:06 +0530
From: Anup Patel <anup@...infault.org>
To: Atish Patra <atish.patra@....com>
Cc: "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
Albert Ou <aou@...s.berkeley.edu>,
Borislav Petkov <bp@...e.de>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Jason Cooper <jason@...edaemon.net>,
Kees Cook <keescook@...omium.org>,
linux-riscv <linux-riscv@...ts.infradead.org>,
Mao Han <han_mao@...ky.com>, Marc Zyngier <maz@...nel.org>,
Mike Rapoport <rppt@...ux.ibm.com>,
Nick Hu <nickhu@...estech.com>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Vincent Chen <vincent.chen@...ive.com>
Subject: Re: [PATCH v9 12/12] irqchip/sifive-plic: Initialize the plic handler
when cpu comes online
On Fri, Feb 21, 2020 at 6:14 AM Atish Patra <atish.patra@....com> wrote:
>
> Currently, plic threshold and priority are only initialized once in the
> beginning. However, threshold can be set to disabled if cpu is marked
> offline with cpu hotplug feature. This will not allow to change the
> irq affinity to a cpu that just came online.
>
> Add plic specific cpu hotplug callback and initialize the per cpu handler
> when cpu comes online.
>
> Signed-off-by: Atish Patra <atish.patra@....com>
> ---
> arch/riscv/kernel/traps.c | 2 +-
> drivers/irqchip/irq-sifive-plic.c | 38 +++++++++++++++++++++++++++----
> include/linux/cpuhotplug.h | 1 +
> 3 files changed, 36 insertions(+), 5 deletions(-)
>
> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> index 8e13ad45ccaa..16c59807da6a 100644
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -157,5 +157,5 @@ void trap_init(void)
> /* Set the exception vector address */
> csr_write(CSR_TVEC, &handle_exception);
> /* Enable interrupts */
> - csr_write(CSR_IE, IE_SIE | IE_EIE);
> + csr_write(CSR_IE, IE_SIE);
> }
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index aa4af886e43a..7c7f37393f99 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -4,6 +4,7 @@
> * 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>
> @@ -55,6 +56,9 @@
> #define CONTEXT_THRESHOLD 0x00
> #define CONTEXT_CLAIM 0x04
>
> +#define PLIC_DISABLE_THRESHOLD 0xf
> +#define PLIC_ENABLE_THRESHOLD 0
> +
> static void __iomem *plic_regs;
>
> struct plic_handler {
> @@ -230,6 +234,32 @@ static int plic_find_hart_id(struct device_node *node)
> return -1;
> }
>
> +static void plic_set_threshold(struct plic_handler *handler, u32 threshold)
> +{
> + /* priority must be > threshold to trigger an interrupt */
> + writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);
> +}
> +
> +static int plic_dying_cpu(unsigned int cpu)
> +{
> + struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
> +
> + csr_clear(CSR_IE, IE_EIE);
> + plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
> +
> + return 0;
> +}
> +
> +static int plic_starting_cpu(unsigned int cpu)
> +{
> + struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
> +
> + csr_set(CSR_IE, IE_EIE);
> + plic_set_threshold(handler, PLIC_ENABLE_THRESHOLD);
> +
> + return 0;
> +}
> +
> static int __init plic_init(struct device_node *node,
> struct device_node *parent)
> {
> @@ -267,7 +297,6 @@ static int __init plic_init(struct device_node *node,
> struct plic_handler *handler;
> irq_hw_number_t hwirq;
> int cpu, hartid;
> - u32 threshold = 0;
>
> if (of_irq_parse_one(node, i, &parent)) {
> pr_err("failed to parse parent for context %d.\n", i);
> @@ -301,7 +330,7 @@ static int __init plic_init(struct device_node *node,
> handler = per_cpu_ptr(&plic_handlers, cpu);
> if (handler->present) {
> pr_warn("handler already present for context %d.\n", i);
> - threshold = 0xffffffff;
> + plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
> goto done;
> }
>
> @@ -313,13 +342,14 @@ static int __init plic_init(struct device_node *node,
> plic_regs + ENABLE_BASE + i * ENABLE_PER_HART;
>
> done:
> - /* priority must be > threshold to trigger an interrupt */
> - writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);
> for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
> plic_toggle(handler, hwirq, 0);
> nr_handlers++;
> }
>
> + cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
> + "irqchip/sifive/plic:starting",
> + plic_starting_cpu, plic_dying_cpu);
> pr_info("mapped %d interrupts with %d handlers for %d contexts.\n",
> nr_irqs, nr_handlers, nr_contexts);
> set_handle_irq(plic_handle_irq);
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index d37c17e68268..77d70b633531 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -102,6 +102,7 @@ enum cpuhp_state {
> CPUHP_AP_IRQ_ARMADA_XP_STARTING,
> CPUHP_AP_IRQ_BCM2836_STARTING,
> CPUHP_AP_IRQ_MIPS_GIC_STARTING,
> + CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
> CPUHP_AP_ARM_MVEBU_COHERENCY,
> CPUHP_AP_MICROCODE_LOADER,
> CPUHP_AP_PERF_X86_AMD_UNCORE_STARTING,
> --
> 2.25.0
>
Looks good to me.
Reviewed-by: Anup Patel <anup@...infault.org>
I will rebase my RISC-V local interrupt controller driver patches
upon this patch series.
Regards,
Anup
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