[PATCH V2 08/10] irqchip, gicv3, its: Probe ITS in the ACPI way.

[Tomasz Nowicki <tn@semihalf.com>]

Since we prepared ITS for being initialized different that via DT,
it is now possible to parse MADT and pass mandatory info to
firmware-agnostic ITS init call.

Note that we are using here IORT lib to keep track of allocated
domain handler which will be used to build PCI MSI domain on top
in the later patches.

Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
---
 drivers/irqchip/irq-gic-v3-its.c | 56 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index fecb7a6..2adb220 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -15,10 +15,12 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/acpi.h>
 #include <linux/bitmap.h>
 #include <linux/cpu.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
+#include <linux/iort.h>
 #include <linux/log2.h>
 #include <linux/mm.h>
 #include <linux/msi.h>
@@ -1272,6 +1274,11 @@ static int its_irq_gic_domain_alloc(struct irq_domain *domain,
 		fwspec.param[0] = GIC_IRQ_TYPE_LPI;
 		fwspec.param[1] = hwirq;
 		fwspec.param[2] = IRQ_TYPE_EDGE_RISING;
+	} else if (is_fwnode_irqchip(domain->parent->fwnode)) {
+		fwspec.fwnode = domain->parent->fwnode;
+		fwspec.param_count = 2;
+		fwspec.param[0] = hwirq;
+		fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
 	} else {
 		return -EINVAL;
 	}
@@ -1594,6 +1601,52 @@ int its_cpu_init(void)
 	return 0;
 }
 
+#ifdef CONFIG_ACPI
+
+#define ACPI_GICV3_ITS_MEM_SIZE (2 * SZ_64K)
+
+static struct irq_domain *its_parent __initdata;
+
+static int __init
+gic_acpi_parse_madt_its(struct acpi_subtable_header *header,
+			const unsigned long end)
+{
+	struct acpi_madt_generic_translator *its_entry;
+	struct fwnode_handle *domain_handle;
+	int err;
+
+	its_entry = (struct acpi_madt_generic_translator *)header;
+	domain_handle = irq_domain_alloc_fwnode((void *)its_entry->base_address);
+	if (!domain_handle) {
+		pr_err("Unable to allocate GICv2m domain token\n");
+		return -ENOMEM;
+	}
+
+	/* ITS works as msi controller in ACPI case */
+	err = its_probe_one(its_entry->base_address, ACPI_GICV3_ITS_MEM_SIZE,
+			    its_parent, true, domain_handle);
+	if (err) {
+		irq_domain_free_fwnode(domain_handle);
+		return err;
+	}
+	iort_register_domain_token(its_entry->translation_id, domain_handle);
+	return 0;
+}
+
+void __init its_acpi_probe(struct irq_domain *parent_domain)
+{
+	int count;
+
+	its_parent = parent_domain;
+	count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
+				      gic_acpi_parse_madt_its, 0);
+	if (count <= 0)
+		pr_info("No valid GIC ITS entries exist\n");
+}
+#else
+static inline void __init its_acpi_probe(struct irq_domain *parent_domain) { }
+#endif
+
 static struct of_device_id its_device_id[] = {
 	{	.compatible	= "arm,gic-v3-its",	},
 	{},
@@ -1610,7 +1663,8 @@ int __init its_init(struct fwnode_handle *handle, struct rdists *rdists,
 		     np = of_find_matching_node(np, its_device_id)) {
 			its_of_probe(np, parent_domain);
 		}
-	}
+	} else
+		its_acpi_probe(parent_domain);
 
 	if (list_empty(&its_nodes)) {
 		pr_warn("ITS: No ITS available, not enabling LPIs\n");
-- 
1.9.1