ARM: GIC: Convert GIC library to use the IO relaxed operations

The GIC register accesses today make use of readl()/writel()
which prove to be very expensive when used along with mandatory
barriers. This mandatory barriers also introduces an un-necessary
and expensive l2x0_sync() operation. On Cortex-A9 MP cores, GIC
IO accesses from CPU are direct and doesn't go through L2X0 write
buffer.

A DSB before writel_relaxed() in gic_raise_softirq() is added to be
compliant with the Barrier Litmus document - the mailbox scenario.

Change-Id: I4955471aefb7d54e209859813973226bfc3db464
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: srinidhi kasagar <srinidhi.kasagar@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/24148
Reviewed-by: QATEST
Tested-by: Jonas ABERG <jonas.aberg@stericsson.com>

1 files changed, 27 insertions, 24 deletions

diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c
index cb6b041c39d..197ddcc9d7a 100644
--- a/arch/arm/common/gic.c
+++ b/arch/arm/common/gic.c
@@ -89,7 +89,7 @@ static void gic_ack_irq(struct irq_data *d)
 	spin_lock(&irq_controller_lock);
 	if (gic_arch_extn.irq_ack)
 		gic_arch_extn.irq_ack(d);
-	writel(gic_irq(d), gic_cpu_base(d) + GIC_CPU_EOI);
+	writel_relaxed(gic_irq(d), gic_cpu_base(d) + GIC_CPU_EOI);
 	spin_unlock(&irq_controller_lock);
 }
 
@@ -98,7 +98,7 @@ static void gic_mask_irq(struct irq_data *d)
 	u32 mask = 1 << (d->irq % 32);
 
 	spin_lock(&irq_controller_lock);
-	writel(mask, gic_dist_base(d) + GIC_DIST_ENABLE_CLEAR + (gic_irq(d) / 32) * 4);
+	writel_relaxed(mask, gic_dist_base(d) + GIC_DIST_ENABLE_CLEAR + (gic_irq(d) / 32) * 4);
 	if (gic_arch_extn.irq_mask)
 		gic_arch_extn.irq_mask(d);
 	spin_unlock(&irq_controller_lock);
@@ -111,7 +111,7 @@ static void gic_unmask_irq(struct irq_data *d)
 	spin_lock(&irq_controller_lock);
 	if (gic_arch_extn.irq_unmask)
 		gic_arch_extn.irq_unmask(d);
-	writel(mask, gic_dist_base(d) + GIC_DIST_ENABLE_SET + (gic_irq(d) / 32) * 4);
+	writel_relaxed(mask, gic_dist_base(d) + GIC_DIST_ENABLE_SET + (gic_irq(d) / 32) * 4);
 	spin_unlock(&irq_controller_lock);
 }
 
@@ -138,7 +138,7 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
 	if (gic_arch_extn.irq_set_type)
 		gic_arch_extn.irq_set_type(d, type);
 
-	val = readl(base + GIC_DIST_CONFIG + confoff);
+	val = readl_relaxed(base + GIC_DIST_CONFIG + confoff);
 	if (type == IRQ_TYPE_LEVEL_HIGH)
 		val &= ~confmask;
 	else if (type == IRQ_TYPE_EDGE_RISING)
@@ -148,15 +148,15 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
 	 * As recommended by the spec, disable the interrupt before changing
 	 * the configuration
 	 */
-	if (readl(base + GIC_DIST_ENABLE_SET + enableoff) & enablemask) {
-		writel(enablemask, base + GIC_DIST_ENABLE_CLEAR + enableoff);
+	if (readl_relaxed(base + GIC_DIST_ENABLE_SET + enableoff) & enablemask) {
+		writel_relaxed(enablemask, base + GIC_DIST_ENABLE_CLEAR + enableoff);
 		enabled = true;
 	}
 
-	writel(val, base + GIC_DIST_CONFIG + confoff);
+	writel_relaxed(val, base + GIC_DIST_CONFIG + confoff);
 
 	if (enabled)
-		writel(enablemask, base + GIC_DIST_ENABLE_SET + enableoff);
+		writel_relaxed(enablemask, base + GIC_DIST_ENABLE_SET + enableoff);
 
 	spin_unlock(&irq_controller_lock);
 
@@ -188,8 +188,8 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
 
 	spin_lock(&irq_controller_lock);
 	d->node = cpu;
-	val = readl(reg) & ~mask;
-	writel(val | bit, reg);
+	val = readl_relaxed(reg) & ~mask;
+	writel_relaxed(val | bit, reg);
 	spin_unlock(&irq_controller_lock);
 
 	return 0;
@@ -222,7 +222,7 @@ static void gic_handle_cascade_irq(unsigned int irq, struct irq_desc *desc)
 	chip->irq_ack(&desc->irq_data);
 
 	spin_lock(&irq_controller_lock);
-	status = readl(chip_data->cpu_base + GIC_CPU_INTACK);
+	status = readl_relaxed(chip_data->cpu_base + GIC_CPU_INTACK);
 	spin_unlock(&irq_controller_lock);
 
 	gic_irq = (status & 0x3ff);
@@ -272,13 +272,13 @@ static void __init gic_dist_init(struct gic_chip_data *gic,
 	cpumask |= cpumask << 8;
 	cpumask |= cpumask << 16;
 
-	writel(0, base + GIC_DIST_CTRL);
+	writel_relaxed(0, base + GIC_DIST_CTRL);
 
 	/*
 	 * Find out how many interrupts are supported.
 	 * The GIC only supports up to 1020 interrupt sources.
 	 */
-	gic_irqs = readl(base + GIC_DIST_CTR) & 0x1f;
+	gic_irqs = readl_relaxed(base + GIC_DIST_CTR) & 0x1f;
 	gic_irqs = (gic_irqs + 1) * 32;
 	if (gic_irqs > 1020)
 		gic_irqs = 1020;
@@ -287,26 +287,26 @@ static void __init gic_dist_init(struct gic_chip_data *gic,
 	 * Set all global interrupts to be level triggered, active low.
 	 */
 	for (i = 32; i < gic_irqs; i += 16)
-		writel(0, base + GIC_DIST_CONFIG + i * 4 / 16);
+		writel_relaxed(0, base + GIC_DIST_CONFIG + i * 4 / 16);
 
 	/*
 	 * Set all global interrupts to this CPU only.
 	 */
 	for (i = 32; i < gic_irqs; i += 4)
-		writel(cpumask, base + GIC_DIST_TARGET + i * 4 / 4);
+		writel_relaxed(cpumask, base + GIC_DIST_TARGET + i * 4 / 4);
 
 	/*
 	 * Set priority on all global interrupts.
 	 */
 	for (i = 32; i < gic_irqs; i += 4)
-		writel(0xa0a0a0a0, base + GIC_DIST_PRI + i * 4 / 4);
+		writel_relaxed(0xa0a0a0a0, base + GIC_DIST_PRI + i * 4 / 4);
 
 	/*
 	 * Disable all interrupts.  Leave the PPI and SGIs alone
 	 * as these enables are banked registers.
 	 */
 	for (i = 32; i < gic_irqs; i += 32)
-		writel(0xffffffff, base + GIC_DIST_ENABLE_CLEAR + i * 4 / 32);
+		writel_relaxed(0xffffffff, base + GIC_DIST_ENABLE_CLEAR + i * 4 / 32);
 
 	/*
 	 * Limit number of interrupts registered to the platform maximum
@@ -325,7 +325,7 @@ static void __init gic_dist_init(struct gic_chip_data *gic,
 		set_irq_flags(i, IRQF_VALID | IRQF_PROBE);
 	}
 
-	writel(1, base + GIC_DIST_CTRL);
+	writel_relaxed(1, base + GIC_DIST_CTRL);
 }
 
 static void __cpuinit gic_cpu_init(struct gic_chip_data *gic)
@@ -338,17 +338,17 @@ static void __cpuinit gic_cpu_init(struct gic_chip_data *gic)
 	 * Deal with the banked PPI and SGI interrupts - disable all
 	 * PPI interrupts, ensure all SGI interrupts are enabled.
 	 */
-	writel(0xffff0000, dist_base + GIC_DIST_ENABLE_CLEAR);
-	writel(0x0000ffff, dist_base + GIC_DIST_ENABLE_SET);
+	writel_relaxed(0xffff0000, dist_base + GIC_DIST_ENABLE_CLEAR);
+	writel_relaxed(0x0000ffff, dist_base + GIC_DIST_ENABLE_SET);
 
 	/*
 	 * Set priority on PPI and SGI interrupts
 	 */
 	for (i = 0; i < 32; i += 4)
-		writel(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4 / 4);
+		writel_relaxed(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4 / 4);
 
-	writel(0xf0, base + GIC_CPU_PRIMASK);
-	writel(1, base + GIC_CPU_CTRL);
+	writel_relaxed(0xf0, base + GIC_CPU_PRIMASK);
+	writel_relaxed(1, base + GIC_CPU_CTRL);
 }
 
 void __init gic_init(unsigned int gic_nr, unsigned int irq_start,
@@ -392,7 +392,10 @@ void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
 {
 	unsigned long map = *cpus_addr(*mask);
 
+	/* ensure the completion of previous memory access */
+	dsb();
+
 	/* this always happens on GIC0 */
-	writel(map << 16 | irq, gic_data[0].dist_base + GIC_DIST_SOFTINT);
+	writel_relaxed(map << 16 | irq, gic_data[0].dist_base + GIC_DIST_SOFTINT);
 }
 #endif