Re: [PATCH v2 2/4] irqchip: sifive-plic: More flexible plic_irq_toggle()

Atish Patra
2018-11-30T01:40:02Z

On 11/27/18 2:03 AM, Anup Patel wrote:
> We make plic_irq_toggle() more generic so that we can enable/disable
> hwirq for given cpumask. This generic plic_irq_toggle() will be
> eventually used to implement set_affinity for PLIC driver.
>
> Signed-off-by: Anup Patel <anup@brainfault.org>
> ---
> drivers/irqchip/irq-sifive-plic.c | 79 +++++++++++++++----------------
> 1 file changed, 39 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index 56fce648a901..95b4b92ca9b8 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -55,19 +55,26 @@
> #define CONTEXT_THRESHOLD 0x00
> #define CONTEXT_CLAIM 0x04
>
> -static void __iomem *plic_regs;
> -
> struct plic_handler {
> bool present;
> - int ctxid;
> void __iomem *hart_base;
> raw_spinlock_t enable_lock;
> void __iomem *enable_base;
> };
> +
> static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
>
> -static inline void plic_toggle(struct plic_handler *handler,
> - int hwirq, int enable)
> +struct plic_hw {
> + u32 nr_irqs;
> + u32 nr_handlers;
> + u32 nr_mapped;

Why these three are moved inside a structure? I don't see them being
used outside plic_init. Am I missing something ?

> + void __iomem *regs;
> + struct irq_domain *irqdomain;
> +};
> +
> +static struct plic_hw plic;
> +
> +static void plic_toggle(struct plic_handler *handler, int hwirq, int enable)
> {
> u32 __iomem *reg = handler->enable_base + (hwirq / 32);
> u32 hwirq_mask = 1 << (hwirq % 32);
> @@ -80,27 +87,23 @@ static inline void plic_toggle(struct plic_handler *handler,
> raw_spin_unlock(&handler->enable_lock);
> }
>
> -static inline void plic_irq_toggle(struct irq_data *d, int enable)
> +static void plic_irq_toggle(const struct cpumask *mask, int hwirq, int enable)
> {
> int cpu;
>
> - writel(enable, plic_regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
> - for_each_cpu(cpu, irq_data_get_affinity_mask(d)) {
> - struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
> -
> - if (handler->present)
> - plic_toggle(handler, d->hwirq, enable);
> - }
> + writel(enable, plic.regs + PRIORITY_BASE + hwirq * PRIORITY_PER_ID);
> + for_each_cpu(cpu, mask)
> + plic_toggle(per_cpu_ptr(&plic_handlers, cpu), hwirq, enable);

Any specific reason to remove the handler->present check.

Moreover, only this part matches commit text. Most of the other changes
looks like cosmetic cleanup because of variable is moved to a structure.
May be separate patch for those changes if they are are required at all.

> }
>
> static void plic_irq_enable(struct irq_data *d)
> {
> - plic_irq_toggle(d, 1);
> + plic_irq_toggle(irq_data_get_affinity_mask(d), d->hwirq, 1);
> }
>
> static void plic_irq_disable(struct irq_data *d)
> {
> - plic_irq_toggle(d, 0);
> + plic_irq_toggle(irq_data_get_affinity_mask(d), d->hwirq, 0);
> }
>
> static struct irq_chip plic_chip = {
> @@ -127,8 +130,6 @@ static const struct irq_domain_ops plic_irqdomain_ops = {
> .xlate = irq_domain_xlate_onecell,
> };
>
> -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
> @@ -145,7 +146,7 @@ static void plic_handle_irq(struct pt_regs *regs)
>
> csr_clear(sie, SIE_SEIE);
> while ((hwirq = readl(claim))) {
> - int irq = irq_find_mapping(plic_irqdomain, hwirq);
> + int irq = irq_find_mapping(plic.irqdomain, hwirq);
>
> if (unlikely(irq <= 0))
> pr_warn_ratelimited("can't find mapping for hwirq %lu\n",
> @@ -174,36 +175,34 @@ static int plic_find_hart_id(struct device_node *node)
> static int __init plic_init(struct device_node *node,
> struct device_node *parent)
> {
> - int error = 0, nr_handlers, nr_mapped = 0, i;
> - u32 nr_irqs;
> + int error = 0, i;
>
> - if (plic_regs) {
> + if (plic.regs) {
> pr_warn("PLIC already present.\n");
> return -ENXIO;
> }
>
> - plic_regs = of_iomap(node, 0);
> - if (WARN_ON(!plic_regs))
> + plic.regs = of_iomap(node, 0);
> + if (WARN_ON(!plic.regs))
> return -EIO;
>
> error = -EINVAL;
> - of_property_read_u32(node, "riscv,ndev", &nr_irqs);
> - if (WARN_ON(!nr_irqs))
> + of_property_read_u32(node, "riscv,ndev", &plic.nr_irqs);
> + if (WARN_ON(!plic.nr_irqs))
> goto out_iounmap;
>
> - nr_handlers = of_irq_count(node);
> - if (WARN_ON(!nr_handlers))
> + plic.nr_handlers = of_irq_count(node);
> + if (WARN_ON(!plic.nr_handlers))
> goto out_iounmap;
> - if (WARN_ON(nr_handlers < num_possible_cpus()))
> + if (WARN_ON(plic.nr_handlers < num_possible_cpus()))
> goto out_iounmap;
>
> - error = -ENOMEM;
> - plic_irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
> - &plic_irqdomain_ops, NULL);
> - if (WARN_ON(!plic_irqdomain))
> + plic.irqdomain = irq_domain_add_linear(node, plic.nr_irqs + 1,
> + &plic_irqdomain_ops, NULL);
> + if (WARN_ON(!plic.irqdomain))
> goto out_iounmap;
>

Should we return EINVAL if irq_domain_add_linear fails ? Earlier, it was
returning ENOMEM.

> - for (i = 0; i < nr_handlers; i++) {
> + for (i = 0; i < plic.nr_handlers; i++) {
> struct of_phandle_args parent;
> struct plic_handler *handler;
> irq_hw_number_t hwirq;
> @@ -227,27 +226,27 @@ static int __init plic_init(struct device_node *node,
> cpu = riscv_hartid_to_cpuid(hartid);
> handler = per_cpu_ptr(&plic_handlers, cpu);
> handler->present = true;
> - handler->ctxid = i;

The previous patch removed all the usage of ctxid. So this line also can
be included in that patch as well to make it more coherent.

Regards,
Atish
> handler->hart_base =
> - plic_regs + CONTEXT_BASE + i * CONTEXT_PER_HART;
> + plic.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;
> + plic.regs + ENABLE_BASE + i * ENABLE_PER_HART;
>
> /* priority must be > threshold to trigger an interrupt */
> writel(0, handler->hart_base + CONTEXT_THRESHOLD);
> - for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
> + for (hwirq = 1; hwirq <= plic.nr_irqs; hwirq++)
> plic_toggle(handler, hwirq, 0);
> - nr_mapped++;
> +
> + plic.nr_mapped++;
> }
>
> pr_info("mapped %d interrupts to %d (out of %d) handlers.\n",
> - nr_irqs, nr_mapped, nr_handlers);
> + plic.nr_irqs, plic.nr_mapped, plic.nr_handlers);
> set_handle_irq(plic_handle_irq);
> return 0;
>
> out_iounmap:
> - iounmap(plic_regs);
> + iounmap(plic.regs);
> return error;
> }
>
>