irqchip: GICv3: ITS: irqchip implementation

The usual methods that are used to present an irqchip to the rest
of the kernel

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1416839720-18400-6-git-send-email-marc.zyngier@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-gic-v3-its.c

@@ -40,6 +40,8 @@
 
 #define ITS_FLAGS_CMDQ_NEEDS_FLUSHING		(1 << 0)
 
+#define RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING	(1 << 0)
+
 /*
  * Collection structure - just an ID, and a redistributor address to
  * ping. We use one per CPU as a bag of interrupts assigned to this
@@ -509,3 +511,78 @@ static void its_send_invall(struct its_node *its, struct its_collection *col)
 
 	its_send_single_command(its, its_build_invall_cmd, &desc);
 }
+
+/*
+ * irqchip functions - assumes MSI, mostly.
+ */
+
+static inline u32 its_get_event_id(struct irq_data *d)
+{
+	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
+	return d->hwirq - its_dev->lpi_base;
+}
+
+static void lpi_set_config(struct irq_data *d, bool enable)
+{
+	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
+	irq_hw_number_t hwirq = d->hwirq;
+	u32 id = its_get_event_id(d);
+	u8 *cfg = page_address(gic_rdists->prop_page) + hwirq - 8192;
+
+	if (enable)
+		*cfg |= LPI_PROP_ENABLED;
+	else
+		*cfg &= ~LPI_PROP_ENABLED;
+
+	/*
+	 * Make the above write visible to the redistributors.
+	 * And yes, we're flushing exactly: One. Single. Byte.
+	 * Humpf...
+	 */
+	if (gic_rdists->flags & RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING)
+		__flush_dcache_area(cfg, sizeof(*cfg));
+	else
+		dsb(ishst);
+	its_send_inv(its_dev, id);
+}
+
+static void its_mask_irq(struct irq_data *d)
+{
+	lpi_set_config(d, false);
+}
+
+static void its_unmask_irq(struct irq_data *d)
+{
+	lpi_set_config(d, true);
+}
+
+static void its_eoi_irq(struct irq_data *d)
+{
+	gic_write_eoir(d->hwirq);
+}
+
+static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
+			    bool force)
+{
+	unsigned int cpu = cpumask_any_and(mask_val, cpu_online_mask);
+	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
+	struct its_collection *target_col;
+	u32 id = its_get_event_id(d);
+
+	if (cpu >= nr_cpu_ids)
+		return -EINVAL;
+
+	target_col = &its_dev->its->collections[cpu];
+	its_send_movi(its_dev, target_col, id);
+	its_dev->collection = target_col;
+
+	return IRQ_SET_MASK_OK_DONE;
+}
+
+static struct irq_chip its_irq_chip = {
+	.name			= "ITS",
+	.irq_mask		= its_mask_irq,
+	.irq_unmask		= its_unmask_irq,
+	.irq_eoi		= its_eoi_irq,
+	.irq_set_affinity	= its_set_affinity,
+};