Re: [PATCH v2 1/4] irqchip: sifive-plic: Pre-compute context hart base and enable base

Atish Patra
2018-11-30T00:35:38Z

On 11/27/18 2:03 AM, Anup Patel wrote:
> This patch does following optimizations:
> 1. Pre-compute hart base for each context handler
> 2. Pre-compute enable base for each context handler
> 3. Have enable lock for each context handler instead
> of global plic_toggle_lock
>
> Signed-off-by: Anup Patel <anup@brainfault.org>
> ---
> drivers/irqchip/irq-sifive-plic.c | 41 +++++++++++++------------------
> 1 file changed, 17 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index 357e9daf94ae..56fce648a901 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -60,36 +60,24 @@ 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;

It should be u32. Otherwise, plic_toggle calculates incorrect address
and it does not boot on Unlheased.

> };
> static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
>
> -static inline void __iomem *plic_hart_offset(int ctxid)
> +static inline void plic_toggle(struct plic_handler *handler,
> + int hwirq, int enable)
> {
> - return plic_regs + CONTEXT_BASE + ctxid * CONTEXT_PER_HART;
> -}
> -
> -static inline u32 __iomem *plic_enable_base(int ctxid)
> -{
> - return plic_regs + ENABLE_BASE + ctxid * ENABLE_PER_HART;
> -}
> -
> -/*
> - * Protect mask operations on the registers given that we can't assume that
> - * atomic memory operations work on them.
> - */

Should we keep the comment for enable_lock ?

> -static DEFINE_RAW_SPINLOCK(plic_toggle_lock);
> -
> -static inline void plic_toggle(int ctxid, int hwirq, int enable)
> -{
> - u32 __iomem *reg = plic_enable_base(ctxid) + (hwirq / 32);
> + u32 __iomem *reg = handler->enable_base + (hwirq / 32);
> u32 hwirq_mask = 1 << (hwirq % 32);
>
> - raw_spin_lock(&plic_toggle_lock);
> + raw_spin_lock(&handler->enable_lock);
> if (enable)
> writel(readl(reg) | hwirq_mask, reg);
> else
> writel(readl(reg) & ~hwirq_mask, reg);
> - raw_spin_unlock(&plic_toggle_lock);
> + raw_spin_unlock(&handler->enable_lock);
> }
>
> static inline void plic_irq_toggle(struct irq_data *d, int enable)
> @@ -101,7 +89,7 @@ static inline void plic_irq_toggle(struct irq_data *d, int enable)
> struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
>
> if (handler->present)
> - plic_toggle(handler->ctxid, d->hwirq, enable);
> + plic_toggle(handler, d->hwirq, enable);
> }
> }
>
> @@ -150,7 +138,7 @@ static struct irq_domain *plic_irqdomain;
> static void plic_handle_irq(struct pt_regs *regs)
> {
> struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
> - void __iomem *claim = plic_hart_offset(handler->ctxid) + CONTEXT_CLAIM;
> + void __iomem *claim = handler->hart_base + CONTEXT_CLAIM;
> irq_hw_number_t hwirq;
>
> WARN_ON_ONCE(!handler->present);
> @@ -240,11 +228,16 @@ static int __init plic_init(struct device_node *node,
> handler = per_cpu_ptr(&plic_handlers, cpu);
> handler->present = true;
> handler->ctxid = i;
> + handler->hart_base =
> + 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;
>
> /* priority must be > threshold to trigger an interrupt */
> - writel(0, plic_hart_offset(i) + CONTEXT_THRESHOLD);
> + writel(0, handler->hart_base + CONTEXT_THRESHOLD);
> for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
> - plic_toggle(i, hwirq, 0);
> + plic_toggle(handler, hwirq, 0);
> nr_mapped++;
> }
>
>