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

Anup Patel
2018-11-27T10:03:14Z

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;
};
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.
- */
-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++;
}

--
2.17.1