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Subject[PATCH v2 03/12] irqchip: mips-gic: Introduce gic_with_each_online_cpu()
Date
From: Paul Burton <paulburton@kernel.org>

A few pieces of code in the MIPS GIC driver operate on the GIC local
register block for each online CPU, accessing each via the GIC's
other/redirect register block. This patch abstracts the process of
iterating over online CPUs & configuring the other/redirect region to
access their registers through a new gic_with_each_online_cpu() macro.

This simplifies users of the new macro slightly, and more importantly
prepares us for handling multi-cluster systems where the register
configuration will be done via the CM's GCR_CL_REDIRECT register. By
abstracting all other/redirect block configuration through this macro,
and the __gic_with_next_online_cpu() function which backs it, users will
trivially gain support for multi-cluster when it is implemented in
__gic_with_next_online_cpu().

Signed-off-by: Paul Burton <paulburton@kernel.org>
Signed-off-by: Chao-ying Fu <cfu@wavecomp.com>
Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@syrmia.com>

diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index ff89b36267dd..4872bebe24cf 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -65,6 +65,45 @@ static struct gic_all_vpes_chip_data {
bool mask;
} gic_all_vpes_chip_data[GIC_NUM_LOCAL_INTRS];

+static int __gic_with_next_online_cpu(int prev)
+{
+ unsigned int cpu;
+
+ /* Discover the next online CPU */
+ cpu = cpumask_next(prev, cpu_online_mask);
+
+ /* If there isn't one, we're done */
+ if (cpu >= nr_cpu_ids)
+ return cpu;
+
+ /*
+ * Lock access to the next CPU's GIC local register block.
+ *
+ * In the single cluster case we simply set GIC_VL_OTHER. The caller
+ * holds gic_lock so nothing can clobber the value we write.
+ */
+ write_gic_vl_other(mips_cm_vp_id(cpu));
+
+ return cpu;
+}
+
+/**
+ * gic_with_each_online_cpu() - Iterate over online CPUs, access local registers
+ * @cpu: An integer variable to hold the current CPU number
+ *
+ * Iterate over online CPUs & configure the other/redirect register region to
+ * access each CPUs GIC local register block, which can be accessed from the
+ * loop body using read_gic_vo_*() or write_gic_vo_*() accessor functions or
+ * their derivatives.
+ *
+ * The caller must hold gic_lock throughout the loop, such that GIC_VL_OTHER
+ * cannot be clobbered.
+ */
+#define gic_with_each_online_cpu(cpu) \
+ for ((cpu) = __gic_with_next_online_cpu(-1); \
+ (cpu) = __gic_with_next_online_cpu(cpu), \
+ (cpu) < nr_cpu_ids;)
+
static void gic_clear_pcpu_masks(unsigned int intr)
{
unsigned int i;
@@ -357,10 +396,8 @@ static void gic_mask_local_irq_all_vpes(struct irq_data *d)
cd->mask = false;

spin_lock_irqsave(&gic_lock, flags);
- for_each_online_cpu(cpu) {
- write_gic_vl_other(mips_cm_vp_id(cpu));
+ gic_with_each_online_cpu(cpu)
write_gic_vo_rmask(BIT(intr));
- }
spin_unlock_irqrestore(&gic_lock, flags);
}

@@ -375,10 +412,8 @@ static void gic_unmask_local_irq_all_vpes(struct irq_data *d)
cd->mask = true;

spin_lock_irqsave(&gic_lock, flags);
- for_each_online_cpu(cpu) {
- write_gic_vl_other(mips_cm_vp_id(cpu));
+ gic_with_each_online_cpu(cpu)
write_gic_vo_smask(BIT(intr));
- }
spin_unlock_irqrestore(&gic_lock, flags);
}

@@ -532,10 +567,8 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int virq,
return -EPERM;

spin_lock_irqsave(&gic_lock, flags);
- for_each_online_cpu(cpu) {
- write_gic_vl_other(mips_cm_vp_id(cpu));
+ gic_with_each_online_cpu(cpu)
write_gic_vo_map(mips_gic_vx_map_reg(intr), map);
- }
spin_unlock_irqrestore(&gic_lock, flags);

return 0;
--
2.17.1
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