irqchip/gic-v3: ACPI: Add redistributor support via GICC structures

Following ACPI spec:
On systems supporting GICv3 and above, GICR Base Address in MADT GICC
structure holds the 64-bit physical address of the associated Redistributor.
If all of the GIC Redistributors are in the always-on power domain,
GICR structures should be used to describe the Redistributors instead,
and this field must be set to 0.

It means that we have two ways to initialize registirbutors map.
1. via GICD structure which can accommodate many redistributors as a region
2. via GICC which is able to describe single redistributor

This patch is going to add support for second option.
Considering redistributors, GICD and GICC subtables have be mutually
exclusive. While discovering and mapping redistributor, we need to know
its size in advance. For the GICC case, redistributor can be in
a power-domain that is off, thus we cannot relay on GICR TYPER register.
Therefore, we get GIC version from distributor register and map 2xSZ_64K
for GICv3 and 4xSZ_64K for GICv4.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-gic-v3.c

@@ -40,6 +40,7 @@
 struct redist_region {
 	void __iomem		*redist_base;
 	phys_addr_t		phys_base;
+	bool			single_redist;
 };
 
 struct gic_chip_data {
@@ -436,6 +437,9 @@ static int gic_populate_rdist(void)
 				return 0;
 			}
 
+			if (gic_data.redist_regions[i].single_redist)
+				break;
+
 			if (gic_data.redist_stride) {
 				ptr += gic_data.redist_stride;
 			} else {
@@ -964,8 +968,21 @@ out_unmap_dist:
 IRQCHIP_DECLARE(gic_v3, "arm,gic-v3", gic_of_init);
 
 #ifdef CONFIG_ACPI
+static void __iomem *dist_base;
 static struct redist_region *redist_regs __initdata;
 static u32 nr_redist_regions __initdata;
+static bool single_redist;
+
+static void __init
+gic_acpi_register_redist(phys_addr_t phys_base, void __iomem *redist_base)
+{
+	static int count = 0;
+
+	redist_regs[count].phys_base = phys_base;
+	redist_regs[count].redist_base = redist_base;
+	redist_regs[count].single_redist = single_redist;
+	count++;
+}
 
 static int __init
 gic_acpi_parse_madt_redist(struct acpi_subtable_header *header,
@@ -974,7 +991,6 @@ gic_acpi_parse_madt_redist(struct acpi_subtable_header *header,
 	struct acpi_madt_generic_redistributor *redist =
 			(struct acpi_madt_generic_redistributor *)header;
 	void __iomem *redist_base;
-	static int count = 0;
 
 	redist_base = ioremap(redist->base_address, redist->length);
 	if (!redist_base) {
@@ -982,12 +998,49 @@ gic_acpi_parse_madt_redist(struct acpi_subtable_header *header,
 		return -ENOMEM;
 	}
 
-	redist_regs[count].phys_base = redist->base_address;
-	redist_regs[count].redist_base = redist_base;
-	count++;
+	gic_acpi_register_redist(redist->base_address, redist_base);
 	return 0;
 }
 
+static int __init
+gic_acpi_parse_madt_gicc(struct acpi_subtable_header *header,
+			 const unsigned long end)
+{
+	struct acpi_madt_generic_interrupt *gicc =
+				(struct acpi_madt_generic_interrupt *)header;
+	u32 reg = readl_relaxed(dist_base + GICD_PIDR2) & GIC_PIDR2_ARCH_MASK;
+	u32 size = reg == GIC_PIDR2_ARCH_GICv4 ? SZ_64K * 4 : SZ_64K * 2;
+	void __iomem *redist_base;
+
+	redist_base = ioremap(gicc->gicr_base_address, size);
+	if (!redist_base)
+		return -ENOMEM;
+
+	gic_acpi_register_redist(gicc->gicr_base_address, redist_base);
+	return 0;
+}
+
+static int __init gic_acpi_collect_gicr_base(void)
+{
+	acpi_tbl_entry_handler redist_parser;
+	enum acpi_madt_type type;
+
+	if (single_redist) {
+		type = ACPI_MADT_TYPE_GENERIC_INTERRUPT;
+		redist_parser = gic_acpi_parse_madt_gicc;
+	} else {
+		type = ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR;
+		redist_parser = gic_acpi_parse_madt_redist;
+	}
+
+	/* Collect redistributor base addresses in GICR entries */
+	if (acpi_table_parse_madt(type, redist_parser, 0) > 0)
+		return 0;
+
+	pr_info("No valid GICR entries exist\n");
+	return -ENODEV;
+}
+
 static int __init gic_acpi_match_gicr(struct acpi_subtable_header *header,
 				  const unsigned long end)
 {
@@ -995,6 +1048,46 @@ static int __init gic_acpi_match_gicr(struct acpi_subtable_header *header,
 	return 0;
 }
 
+static int __init gic_acpi_match_gicc(struct acpi_subtable_header *header,
+				      const unsigned long end)
+{
+	struct acpi_madt_generic_interrupt *gicc =
+				(struct acpi_madt_generic_interrupt *)header;
+
+	/*
+	 * If GICC is enabled and has valid gicr base address, then it means
+	 * GICR base is presented via GICC
+	 */
+	if ((gicc->flags & ACPI_MADT_ENABLED) && gicc->gicr_base_address)
+		return 0;
+
+	return -ENODEV;
+}
+
+static int __init gic_acpi_count_gicr_regions(void)
+{
+	int count;
+
+	/*
+	 * Count how many redistributor regions we have. It is not allowed
+	 * to mix redistributor description, GICR and GICC subtables have to be
+	 * mutually exclusive.
+	 */
+	count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR,
+				      gic_acpi_match_gicr, 0);
+	if (count > 0) {
+		single_redist = false;
+		return count;
+	}
+
+	count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
+				      gic_acpi_match_gicc, 0);
+	if (count > 0)
+		single_redist = true;
+
+	return count;
+}
+
 static bool __init acpi_validate_gic_table(struct acpi_subtable_header *header,
 					   struct acpi_probe_entry *ape)
 {
@@ -1006,8 +1099,7 @@ static bool __init acpi_validate_gic_table(struct acpi_subtable_header *header,
 		return false;
 
 	/* We need to do that exercise anyway, the sooner the better */
-	count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR,
-				      gic_acpi_match_gicr, 0);
+	count = gic_acpi_count_gicr_regions();
 	if (count <= 0)
 		return false;
 
@@ -1022,8 +1114,7 @@ gic_acpi_init(struct acpi_subtable_header *header, const unsigned long end)
 {
 	struct acpi_madt_generic_distributor *dist;
 	struct fwnode_handle *domain_handle;
-	void __iomem *dist_base;
-	int i, err, count;
+	int i, err;
 
 	/* Get distributor base address */
 	dist = (struct acpi_madt_generic_distributor *)header;
@@ -1046,12 +1137,9 @@ gic_acpi_init(struct acpi_subtable_header *header, const unsigned long end)
 		goto out_dist_unmap;
 	}
 
-	count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR,
-				      gic_acpi_parse_madt_redist, 0);
-	if (count <= 0) {
-		err = -ENODEV;
+	err = gic_acpi_collect_gicr_base();
+	if (err)
 		goto out_redist_unmap;
-	}
 
 	domain_handle = irq_domain_alloc_fwnode(dist_base);
 	if (!domain_handle) {