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authorNicolas Pitre <nicolas.pitre@linaro.org>2012-04-12 01:40:31 -0400
committerNicolas Pitre <nicolas.pitre@linaro.org>2013-07-30 09:02:12 -0400
commit1a6b69b6548cd0dd82549393f30dd982ceeb79d2 (patch)
tree97758dd77421bcacb3191c5347194d3d48940a3b /drivers/irqchip
parent71a8986d7e4845b6fca1298fe6e3233ce6fde0b7 (diff)
downloadlinux-1a6b69b6548cd0dd82549393f30dd982ceeb79d2.tar.bz2
ARM: gic: add CPU migration support
This is required by the big.LITTLE switcher code. The gic_migrate_target() changes the CPU interface mapping for the current CPU to redirect SGIs to the specified interface, and it also updates the target CPU for each interrupts to that CPU interface if they were targeting the current interface. Finally, pending SGIs for the current CPU are forwarded to the new interface. Because Linux does not use it, the SGI source information for the forwarded SGIs is not preserved. Neither is the source information for the SGIs sent by the current CPU to other CPUs adjusted to match the new CPU interface mapping. The required registers are banked so only the target CPU could do it. Signed-off-by: Nicolas Pitre <nico@linaro.org>
Diffstat (limited to 'drivers/irqchip')
-rw-r--r--drivers/irqchip/irq-gic.c87
1 files changed, 84 insertions, 3 deletions
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index ee7c50312066..268874ac75e6 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -253,10 +253,9 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
if (cpu >= NR_GIC_CPU_IF || cpu >= nr_cpu_ids)
return -EINVAL;
+ raw_spin_lock(&irq_controller_lock);
mask = 0xff << shift;
bit = gic_cpu_map[cpu] << shift;
-
- raw_spin_lock(&irq_controller_lock);
val = readl_relaxed(reg) & ~mask;
writel_relaxed(val | bit, reg);
raw_spin_unlock(&irq_controller_lock);
@@ -646,7 +645,9 @@ static void __init gic_pm_init(struct gic_chip_data *gic)
void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
{
int cpu;
- unsigned long map = 0;
+ unsigned long flags, map = 0;
+
+ raw_spin_lock_irqsave(&irq_controller_lock, flags);
/* Convert our logical CPU mask into a physical one. */
for_each_cpu(cpu, mask)
@@ -660,6 +661,86 @@ void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
/* this always happens on GIC0 */
writel_relaxed(map << 16 | irq, gic_data_dist_base(&gic_data[0]) + GIC_DIST_SOFTINT);
+
+ raw_spin_unlock_irqrestore(&irq_controller_lock, flags);
+}
+#endif
+
+#ifdef CONFIG_BL_SWITCHER
+/*
+ * gic_migrate_target - migrate IRQs to another CPU interface
+ *
+ * @new_cpu_id: the CPU target ID to migrate IRQs to
+ *
+ * Migrate all peripheral interrupts with a target matching the current CPU
+ * to the interface corresponding to @new_cpu_id. The CPU interface mapping
+ * is also updated. Targets to other CPU interfaces are unchanged.
+ * This must be called with IRQs locally disabled.
+ */
+void gic_migrate_target(unsigned int new_cpu_id)
+{
+ unsigned int cur_cpu_id, gic_irqs, gic_nr = 0;
+ void __iomem *dist_base;
+ int i, ror_val, cpu = smp_processor_id();
+ u32 val, cur_target_mask, active_mask;
+
+ if (gic_nr >= MAX_GIC_NR)
+ BUG();
+
+ dist_base = gic_data_dist_base(&gic_data[gic_nr]);
+ if (!dist_base)
+ return;
+ gic_irqs = gic_data[gic_nr].gic_irqs;
+
+ cur_cpu_id = __ffs(gic_cpu_map[cpu]);
+ cur_target_mask = 0x01010101 << cur_cpu_id;
+ ror_val = (cur_cpu_id - new_cpu_id) & 31;
+
+ raw_spin_lock(&irq_controller_lock);
+
+ /* Update the target interface for this logical CPU */
+ gic_cpu_map[cpu] = 1 << new_cpu_id;
+
+ /*
+ * Find all the peripheral interrupts targetting the current
+ * CPU interface and migrate them to the new CPU interface.
+ * We skip DIST_TARGET 0 to 7 as they are read-only.
+ */
+ for (i = 8; i < DIV_ROUND_UP(gic_irqs, 4); i++) {
+ val = readl_relaxed(dist_base + GIC_DIST_TARGET + i * 4);
+ active_mask = val & cur_target_mask;
+ if (active_mask) {
+ val &= ~active_mask;
+ val |= ror32(active_mask, ror_val);
+ writel_relaxed(val, dist_base + GIC_DIST_TARGET + i*4);
+ }
+ }
+
+ raw_spin_unlock(&irq_controller_lock);
+
+ /*
+ * Now let's migrate and clear any potential SGIs that might be
+ * pending for us (cur_cpu_id). Since GIC_DIST_SGI_PENDING_SET
+ * is a banked register, we can only forward the SGI using
+ * GIC_DIST_SOFTINT. The original SGI source is lost but Linux
+ * doesn't use that information anyway.
+ *
+ * For the same reason we do not adjust SGI source information
+ * for previously sent SGIs by us to other CPUs either.
+ */
+ for (i = 0; i < 16; i += 4) {
+ int j;
+ val = readl_relaxed(dist_base + GIC_DIST_SGI_PENDING_SET + i);
+ if (!val)
+ continue;
+ writel_relaxed(val, dist_base + GIC_DIST_SGI_PENDING_CLEAR + i);
+ for (j = i; j < i + 4; j++) {
+ if (val & 0xff)
+ writel_relaxed((1 << (new_cpu_id + 16)) | j,
+ dist_base + GIC_DIST_SOFTINT);
+ val >>= 8;
+ }
+ }
}
#endif