irqchip/gic-v3-its: Add probing for VLPI properties

Add the probing code for the ITS VLPI support. This includes
configuring the ITS number if not supporting the single VMOVP
command feature.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 67 insertions, 4 deletions

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 2232250f1442..89da961e949e 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -101,6 +101,7 @@ struct its_node {
 	u32			ite_size;
 	u32			device_ids;
 	int			numa_node;
+	bool			is_v4;
 };
 
 #define ITS_ITT_ALIGN		SZ_256
@@ -133,6 +134,14 @@ static DEFINE_SPINLOCK(its_lock);
 static struct rdists *gic_rdists;
 static struct irq_domain *its_parent;
 
+/*
+ * We have a maximum number of 16 ITSs in the whole system if we're
+ * using the ITSList mechanism
+ */
+#define ITS_LIST_MAX		16
+
+static unsigned long its_list_map;
+
 #define gic_data_rdist()		(raw_cpu_ptr(gic_rdists->rdist))
 #define gic_data_rdist_rd_base()	(gic_data_rdist()->rd_base)
 
@@ -1679,13 +1688,51 @@ static int its_init_domain(struct fwnode_handle *handle, struct its_node *its)
 	return 0;
 }
 
+static int __init its_compute_its_list_map(struct resource *res,
+					   void __iomem *its_base)
+{
+	int its_number;
+	u32 ctlr;
+
+	/*
+	 * This is assumed to be done early enough that we're
+	 * guaranteed to be single-threaded, hence no
+	 * locking. Should this change, we should address
+	 * this.
+	 */
+	its_number = find_first_zero_bit(&its_list_map, ITS_LIST_MAX);
+	if (its_number >= ITS_LIST_MAX) {
+		pr_err("ITS@%pa: No ITSList entry available!\n",
+		       &res->start);
+		return -EINVAL;
+	}
+
+	ctlr = readl_relaxed(its_base + GITS_CTLR);
+	ctlr &= ~GITS_CTLR_ITS_NUMBER;
+	ctlr |= its_number << GITS_CTLR_ITS_NUMBER_SHIFT;
+	writel_relaxed(ctlr, its_base + GITS_CTLR);
+	ctlr = readl_relaxed(its_base + GITS_CTLR);
+	if ((ctlr & GITS_CTLR_ITS_NUMBER) != (its_number << GITS_CTLR_ITS_NUMBER_SHIFT)) {
+		its_number = ctlr & GITS_CTLR_ITS_NUMBER;
+		its_number >>= GITS_CTLR_ITS_NUMBER_SHIFT;
+	}
+
+	if (test_and_set_bit(its_number, &its_list_map)) {
+		pr_err("ITS@%pa: Duplicate ITSList entry %d\n",
+		       &res->start, its_number);
+		return -EINVAL;
+	}
+
+	return its_number;
+}
+
 static int __init its_probe_one(struct resource *res,
 				struct fwnode_handle *handle, int numa_node)
 {
 	struct its_node *its;
 	void __iomem *its_base;
-	u32 val;
-	u64 baser, tmp;
+	u32 val, ctlr;
+	u64 baser, tmp, typer;
 	int err;
 
 	its_base = ioremap(res->start, resource_size(res));
@@ -1718,9 +1765,24 @@ static int __init its_probe_one(struct resource *res,
 	raw_spin_lock_init(&its->lock);
 	INIT_LIST_HEAD(&its->entry);
 	INIT_LIST_HEAD(&its->its_device_list);
+	typer = gic_read_typer(its_base + GITS_TYPER);
 	its->base = its_base;
 	its->phys_base = res->start;
-	its->ite_size = ((gic_read_typer(its_base + GITS_TYPER) >> 4) & 0xf) + 1;
+	its->ite_size = GITS_TYPER_ITT_ENTRY_SIZE(typer);
+	its->is_v4 = !!(typer & GITS_TYPER_VLPIS);
+	if (its->is_v4) {
+		if (!(typer & GITS_TYPER_VMOVP)) {
+			err = its_compute_its_list_map(res, its_base);
+			if (err < 0)
+				goto out_free_its;
+
+			pr_info("ITS@%pa: Using ITS number %d\n",
+				&res->start, err);
+		} else {
+			pr_info("ITS@%pa: Single VMOVP capable\n", &res->start);
+		}
+	}
+
 	its->numa_node = numa_node;
 
 	its->cmd_base = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
@@ -1767,7 +1829,8 @@ static int __init its_probe_one(struct resource *res,
 	}
 
 	gits_write_cwriter(0, its->base + GITS_CWRITER);
-	writel_relaxed(GITS_CTLR_ENABLE, its->base + GITS_CTLR);
+	ctlr = readl_relaxed(its->base + GITS_CTLR);
+	writel_relaxed(ctlr | GITS_CTLR_ENABLE, its->base + GITS_CTLR);
 
 	err = its_init_domain(handle, its);
 	if (err)