irqchip/sifive-plic: Pre-compute context hart base and enable base

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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index 254ecd7..715ef7b 100644 (file)
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -59,37 +59,28 @@ static void __iomem *plic_regs;
 
 struct plic_handler {
        bool                    present;
-       int                     ctxid;
+       void __iomem            *hart_base;
+       /*
+        * Protect mask operations on the registers given that we can't
+        * assume atomic memory operations work on them.
+        */
+       raw_spinlock_t          enable_lock;
+       void __iomem            *enable_base;
 };
 static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
 
-static inline void __iomem *plic_hart_offset(int ctxid)
-{
-       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.
- */
-static DEFINE_RAW_SPINLOCK(plic_toggle_lock);
-
-static inline void plic_toggle(int ctxid, int hwirq, int enable)
+static inline void plic_toggle(struct plic_handler *handler,
+                               int hwirq, int enable)
 {
-       u32 __iomem *reg = plic_enable_base(ctxid) + (hwirq / 32);
+       u32 __iomem *reg = handler->enable_base + (hwirq / 32) * sizeof(u32);
        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 +92,7 @@ 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 +141,7 @@ 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);
@@ -244,12 +235,16 @@ 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++;
        }