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

Atish Patra
2020-02-28T18:25:50Z

On Fri, 2020-02-28 at 09:36 +0530, Anup Patel wrote:
> 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.
>

ok. Sure. I will update the patch.

> > + 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>
>

Thanks.

> Regards,
> Anup

--
Regards,
Atish