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Date:   Fri, 28 Feb 2020 18:25:46 +0000
From:   Atish Patra <Atish.Patra@....com>
To:     "anup@...infault.org" <anup@...infault.org>
CC:     "maz@...nel.org" <maz@...nel.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "palmer@...belt.com" <palmer@...belt.com>,
        "paul.walmsley@...ive.com" <paul.walmsley@...ive.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jason@...edaemon.net" <jason@...edaemon.net>,
        "tglx@...utronix.de" <tglx@...utronix.de>
Subject: Re: [v2 PATCH] irqchip/sifive-plic: Add support for multiple PLICs

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@....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@....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@...infault.org>
> 

Thanks.

> Regards,
> Anup

-- 
Regards,
Atish

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