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

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Date:   Mon, 22 Oct 2018 17:15:14 +0530
From:   Anup Patel <anup@...infault.org>
To:     Palmer Dabbelt <palmer@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>
Cc:     Atish Patra <atish.patra@....com>,
        Christoph Hellwig <hch@...radead.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anup Patel <anup@...infault.org>
Subject: [PATCH 1/4] 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@...infault.org>
---
 drivers/irqchip/irq-sifive-plic.c | 51 +++++++++++++------------------
 1 file changed, 22 insertions(+), 29 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index 357e9daf94ae..f93ec83eaff4 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -36,14 +36,14 @@
  * We always hardwire it to one in Linux.
  */
 #define PRIORITY_BASE			0
-#define     PRIORITY_PER_ID		4
+#define PRIORITY_PER_ID			4
 
 /*
  * Each hart context has a vector of interrupt enable bits associated with it.
  * There's one bit for each interrupt source.
  */
 #define ENABLE_BASE			0x2000
-#define     ENABLE_PER_HART		0x80
+#define ENABLE_PER_HART			0x80
 
 /*
  * Each hart context has a set of control registers associated with it.  Right
@@ -51,45 +51,33 @@
  * take an interrupt, and a register to claim interrupts.
  */
 #define CONTEXT_BASE			0x200000
-#define     CONTEXT_PER_HART		0x1000
-#define     CONTEXT_THRESHOLD		0x00
-#define     CONTEXT_CLAIM		0x04
+#define CONTEXT_PER_HART		0x1000
+#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 __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