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.
Also since a DSB does not guarantee that the device state has
been changed, a read back from the device is introduced wherever
necessary.
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
---
Tested on OMAP4430 SDP.
arch/arm/common/gic.c | 57 ++++++++++++++++++++++++++++--------------------
1 files changed, 33 insertions(+), 24 deletions(-)
diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c
index f70ec7d..e013f65 100644
--- a/arch/arm/common/gic.c
+++ b/arch/arm/common/gic.c
@@ -89,7 +89,9 @@ 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);
+ barrier();
+ readl_relaxed(gic_cpu_base(d) + GIC_CPU_EOI);
spin_unlock(&irq_controller_lock);
}
@@ -98,7 +100,9 @@ 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);
+ barrier();
+ readl_relaxed(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 +115,9 @@ 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);
+ barrier();
+ readl_relaxed(gic_dist_base(d) + GIC_DIST_ENABLE_SET + (gic_irq(d) / 32) * 4);
spin_unlock(&irq_controller_lock);
}
@@ -138,7 +144,7 @@ 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 +154,15 @@ 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 +194,9 @@ 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;
+ barrier();
+ writel_relaxed(val | bit, reg);
spin_unlock(&irq_controller_lock);
return 0;
@@ -222,7 +229,7 @@ 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 +279,13 @@ 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 +294,26 @@ 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
@@ -324,7 +331,7 @@ 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)
@@ -337,17 +344,17 @@ 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,
@@ -392,6 +399,8 @@ void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
unsigned long map = *cpus_addr(*mask);
/* 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);
+ barrier();
+ readl_relaxed(gic_data[0].dist_base + GIC_DIST_SOFTINT);
}
#endif
--
1.6.0.4
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
