LoongArch: Prepare to support multiple pch-pic and pch-msi irqdomain

For systems with two chipsets, there are two related pch-pic and
pch-msi irqdomains, each of which has the same node id as its
parent irqdomain. So we use a structure to mantain the relation
of node and it's parent irqdomain as pch irqdomin, the 'pci_segment'
field is only used to match the pci segment of a pci device when
setting msi irqdomain for the device.

struct acpi_vector_group {
        int node;
        int pci_segment;
        struct irq_domain *parent;
};

The field 'pci_segment' and 'node' are initialized from MCFG, and
the parent irqdomain driver will set field 'parent' by matching same
'node'.
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1658314292-35346-7-git-send-email-lvjianmin@loongson.cn

arch/loongarch/include/asm/irq.h

@@ -48,6 +48,14 @@ void arch_trigger_cpumask_backtrace(const struct cpumask *mask, bool exclude_sel
 #define MAX_IO_PICS 2
 #define NR_IRQS	(64 + (256 * MAX_IO_PICS))
 
+struct acpi_vector_group {
+	int node;
+	int pci_segment;
+	struct irq_domain *parent;
+};
+extern struct acpi_vector_group pch_group[MAX_IO_PICS];
+extern struct acpi_vector_group msi_group[MAX_IO_PICS];
+
 #define CORES_PER_EIO_NODE	4
 
 #define LOONGSON_CPU_UART0_VEC		10 /* CPU UART0 */

arch/loongarch/kernel/irq.c

@@ -31,6 +31,8 @@ struct irq_domain *pch_lpc_domain;
 struct irq_domain *pch_msi_domain[MAX_IO_PICS];
 struct irq_domain *pch_pic_domain[MAX_IO_PICS];
 
+struct acpi_vector_group pch_group[MAX_IO_PICS];
+struct acpi_vector_group msi_group[MAX_IO_PICS];
 /*
  * 'what should we do if we get a hw irq event on an illegal vector'.
  * each architecture has to answer this themselves.
@@ -56,6 +58,41 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 	return 0;
 }
 
+static int __init early_pci_mcfg_parse(struct acpi_table_header *header)
+{
+	struct acpi_table_mcfg *mcfg;
+	struct acpi_mcfg_allocation *mptr;
+	int i, n;
+
+	if (header->length < sizeof(struct acpi_table_mcfg))
+		return -EINVAL;
+
+	n = (header->length - sizeof(struct acpi_table_mcfg)) /
+					sizeof(struct acpi_mcfg_allocation);
+	mcfg = (struct acpi_table_mcfg *)header;
+	mptr = (struct acpi_mcfg_allocation *) &mcfg[1];
+
+	for (i = 0; i < n; i++, mptr++) {
+		msi_group[i].pci_segment = mptr->pci_segment;
+		pch_group[i].node = msi_group[i].node = (mptr->address >> 44) & 0xf;
+	}
+
+	return 0;
+}
+
+static void __init init_vec_parent_group(void)
+{
+	int i;
+
+	for (i = 0; i < MAX_IO_PICS; i++) {
+		msi_group[i].pci_segment = -1;
+		msi_group[i].node = -1;
+		pch_group[i].node = -1;
+	}
+
+	acpi_table_parse(ACPI_SIG_MCFG, early_pci_mcfg_parse);
+}
+
 void __init init_IRQ(void)
 {
 	int i;
@@ -69,6 +106,7 @@ void __init init_IRQ(void)
 	clear_csr_ecfg(ECFG0_IM);
 	clear_csr_estat(ESTATF_IP);
 
+	init_vec_parent_group();
 	irqchip_init();
 #ifdef CONFIG_SMP
 	ipi_irq = EXCCODE_IPI - EXCCODE_INT_START;