Re: [v2 PATCH] irqchip/sifive-plic: Add support for multiple PLICs

Anup Patel
2020-02-28T04:07:15Z

On Sat, Feb 22, 2020 at 4:53 AM Atish Patra <atish.patra@wdc.com> wrote:
>
> Current, PLIC driver can support only 1 PLIC on the board. However,
> there can be multiple PLICs present on a two socket systems in RISC-V.
>
> Modify the driver so that each PLIC handler can have a information
> about individual PLIC registers and an irqdomain associated with it.
>
> Tested on two socket RISC-V system based on VCU118 FPGA connected via
> OmniXtend protocol.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
> This patch is rebased on top of 5.6-rc2 and following plic fix from
> hotplug series.
>
> https://lkml.org/lkml/2020/2/20/1220
>
> Changes from v1->v2:
> 1. Use irq_chip_get_data to retrieve host_data
> 2. Renamed plic_hw to plic_node_ctx
> ---
> drivers/irqchip/irq-sifive-plic.c | 82 ++++++++++++++++++++-----------
> 1 file changed, 52 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index 7c7f37393f99..9b9b6f4def4f 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -59,7 +59,11 @@
> #define PLIC_DISABLE_THRESHOLD 0xf
> #define PLIC_ENABLE_THRESHOLD 0
>
> -static void __iomem *plic_regs;
> +struct plic_node_ctx {

I think "plic_node_ctx" is a non-trivial name. I guess much
simpler and cleaner name will be "plic_priv" because this
structure represents private data for each PLIC instance.

> + struct cpumask lmask;
> + struct irq_domain *irqdomain;
> + void __iomem *regs;
> +};
>
> struct plic_handler {
> bool present;
> @@ -70,6 +74,7 @@ struct plic_handler {
> */
> raw_spinlock_t enable_lock;
> void __iomem *enable_base;
> + struct plic_node_ctx *node_ctx;
> };
> static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
>
> @@ -88,31 +93,41 @@ static inline void plic_toggle(struct plic_handler *handler,
> }
>
> static inline void plic_irq_toggle(const struct cpumask *mask,
> - int hwirq, int enable)
> + struct irq_data *d, int enable)
> {
> int cpu;
> + struct plic_node_ctx *node_ctx = irq_get_chip_data(d->irq);
>
> - writel(enable, plic_regs + PRIORITY_BASE + hwirq * PRIORITY_PER_ID);
> + writel(enable,
> + node_ctx->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
> for_each_cpu(cpu, mask) {
> struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
>
> - if (handler->present)
> - plic_toggle(handler, hwirq, enable);
> + if (handler->present &&
> + cpumask_test_cpu(cpu, &handler->node_ctx->lmask))
> + plic_toggle(handler, d->hwirq, enable);
> }
> }
>
> static void plic_irq_unmask(struct irq_data *d)
> {
> - unsigned int cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
> - cpu_online_mask);
> + struct cpumask amask;
> + unsigned int cpu;
> + struct plic_node_ctx *node_ctx = irq_get_chip_data(d->irq);
> +
> + cpumask_and(&amask, &node_ctx->lmask, cpu_online_mask);
> + cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
> + &amask);
> if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
> return;
> - plic_irq_toggle(cpumask_of(cpu), d->hwirq, 1);
> + plic_irq_toggle(cpumask_of(cpu), d, 1);
> }
>
> static void plic_irq_mask(struct irq_data *d)
> {
> - plic_irq_toggle(cpu_possible_mask, d->hwirq, 0);
> + struct plic_node_ctx *node_ctx = irq_get_chip_data(d->irq);
> +
> + plic_irq_toggle(&node_ctx->lmask, d, 0);
> }
>
> #ifdef CONFIG_SMP
> @@ -120,17 +135,21 @@ static int plic_set_affinity(struct irq_data *d,
> const struct cpumask *mask_val, bool force)
> {
> unsigned int cpu;
> + struct cpumask amask;
> + struct plic_node_ctx *node_ctx = irq_get_chip_data(d->irq);
> +
> + cpumask_and(&amask, &node_ctx->lmask, mask_val);
>
> if (force)
> - cpu = cpumask_first(mask_val);
> + cpu = cpumask_first(&amask);
> else
> - cpu = cpumask_any_and(mask_val, cpu_online_mask);
> + cpu = cpumask_any_and(&amask, cpu_online_mask);
>
> if (cpu >= nr_cpu_ids)
> return -EINVAL;
>
> - plic_irq_toggle(cpu_possible_mask, d->hwirq, 0);
> - plic_irq_toggle(cpumask_of(cpu), d->hwirq, 1);
> + plic_irq_toggle(&node_ctx->lmask, d, 0);
> + plic_irq_toggle(cpumask_of(cpu), d, 1);
>
> irq_data_update_effective_affinity(d, cpumask_of(cpu));
>
> @@ -191,8 +210,6 @@ static const struct irq_domain_ops plic_irqdomain_ops = {
> .free = irq_domain_free_irqs_top,
> };
>
> -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
> @@ -209,7 +226,7 @@ static void plic_handle_irq(struct pt_regs *regs)
>
> csr_clear(CSR_IE, IE_EIE);
> while ((hwirq = readl(claim))) {
> - int irq = irq_find_mapping(plic_irqdomain, hwirq);
> + int irq = irq_find_mapping(handler->node_ctx->irqdomain, hwirq);
>
> if (unlikely(irq <= 0))
> pr_warn_ratelimited("can't find mapping for hwirq %lu\n",
> @@ -265,15 +282,17 @@ static int __init plic_init(struct device_node *node,
> {
> int error = 0, nr_contexts, nr_handlers = 0, i;
> u32 nr_irqs;
> + struct plic_node_ctx *node_ctx;
>
> - if (plic_regs) {
> - pr_warn("PLIC already present.\n");
> - return -ENXIO;
> - }
> + node_ctx = kzalloc(sizeof(*node_ctx), GFP_KERNEL);
> + if (!node_ctx)
> + return -ENOMEM;
>
> - plic_regs = of_iomap(node, 0);
> - if (WARN_ON(!plic_regs))
> - return -EIO;
> + node_ctx->regs = of_iomap(node, 0);
> + if (WARN_ON(!node_ctx->regs)) {
> + error = -EIO;
> + goto out_free_nctx;
> + }
>
> error = -EINVAL;
> of_property_read_u32(node, "riscv,ndev", &nr_irqs);
> @@ -287,9 +306,9 @@ static int __init plic_init(struct device_node *node,
> goto out_iounmap;
>
> error = -ENOMEM;
> - plic_irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
> - &plic_irqdomain_ops, NULL);
> - if (WARN_ON(!plic_irqdomain))
> + node_ctx->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
> + &plic_irqdomain_ops, node_ctx);
> + if (WARN_ON(!node_ctx->irqdomain))
> goto out_iounmap;
>
> for (i = 0; i < nr_contexts; i++) {
> @@ -334,13 +353,14 @@ static int __init plic_init(struct device_node *node,
> goto done;
> }
>
> + cpumask_set_cpu(cpu, &node_ctx->lmask);
> handler->present = true;
> handler->hart_base =
> - plic_regs + CONTEXT_BASE + i * CONTEXT_PER_HART;
> + node_ctx->regs + CONTEXT_BASE + i * CONTEXT_PER_HART;
> raw_spin_lock_init(&handler->enable_lock);
> handler->enable_base =
> - plic_regs + ENABLE_BASE + i * ENABLE_PER_HART;
> -
> + node_ctx->regs + ENABLE_BASE + i * ENABLE_PER_HART;
> + handler->node_ctx = node_ctx;
> done:
> for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
> plic_toggle(handler, hwirq, 0);
> @@ -356,7 +376,9 @@ static int __init plic_init(struct device_node *node,
> return 0;
>
> out_iounmap:
> - iounmap(plic_regs);
> + iounmap(node_ctx->regs);
> +out_free_nctx:
> + kfree(node_ctx);
> return error;
> }
>
> --
> 2.25.0
>

Apart from above nit, looks good to me.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup