[RFC PATCH v2 13/21] irqchip: riscv-intc: Add ACPI support for AIA

[Sunil V L]

The RINTC subtype structure in MADT also has information about other
interrupt controllers like MMIO. So, save those information and provide
interfaces to retrieve them when required by corresponding drivers.

Signed-off-by: Sunil V L <sunilvl at ventanamicro.com>
---
 arch/riscv/include/asm/irq.h     |  19 ++++++
 drivers/irqchip/irq-riscv-intc.c | 102 ++++++++++++++++++++++++++++++-
 2 files changed, 120 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
index 8e10a94430a2..ef102b6fa86e 100644
--- a/arch/riscv/include/asm/irq.h
+++ b/arch/riscv/include/asm/irq.h
@@ -12,8 +12,27 @@
 
 #include <asm-generic/irq.h>
 
+#ifdef CONFIG_ACPI
+
+/*
+ * The ext_intc_id format is as follows:
+ * Bits [31:24] APLIC/PLIC ID
+ * Bits [15:0] APLIC IDC ID / PLIC S-Mode Context ID for this hart
+ */
+#define APLIC_PLIC_ID(x) ((x) >> 24)
+#define IDC_CONTEXT_ID(x) ((x) & 0x0000ffff)
+
+int __init acpi_get_intc_index_hartid(u32 index, unsigned long *hartid);
+int acpi_get_ext_intc_parent_hartid(u8 id, u32 idx, unsigned long *hartid);
+void acpi_get_plic_nr_contexts(u8 id, int *nr_contexts);
+int acpi_get_plic_context(u8 id, u32 idx, int *context_id);
+int __init acpi_get_imsic_mmio_info(u32 index, struct resource *res);
+
+#endif
+
 void riscv_set_intc_hwnode_fn(struct fwnode_handle *(*fn)(void));
 
 struct fwnode_handle *riscv_get_intc_hwnode(void);
+int acpi_imsic_probe(struct fwnode_handle *parent);
 
 #endif /* _ASM_RISCV_IRQ_H */
diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
index bab536bbaf2c..f3aaecde12dd 100644
--- a/drivers/irqchip/irq-riscv-intc.c
+++ b/drivers/irqchip/irq-riscv-intc.c
@@ -18,6 +18,7 @@
 #include <linux/of.h>
 #include <linux/smp.h>
 #include <asm/hwcap.h>
+#include "../pci/pci.h"
 
 static struct irq_domain *intc_domain;
 
@@ -195,13 +196,100 @@ IRQCHIP_DECLARE(riscv, "riscv,cpu-intc", riscv_intc_init);
 
 #ifdef CONFIG_ACPI
 
+struct rintc_data {
+	u32 ext_intc_id;
+	unsigned long hart_id;
+	u64 imsic_addr;
+	u32 imsic_size;
+};
+
+static u32 nr_rintc;
+static struct rintc_data *rintc_acpi_data[NR_CPUS];
+
+int acpi_get_intc_index_hartid(u32 index, unsigned long *hartid)
+{
+	if (index >= nr_rintc)
+		return -1;
+
+	*hartid = rintc_acpi_data[index]->hart_id;
+	return 0;
+}
+
+int acpi_get_ext_intc_parent_hartid(u8 id, u32 idx, unsigned long *hartid)
+{
+	int i, j = 0;
+
+	for (i = 0; i < nr_rintc; i++) {
+		if (APLIC_PLIC_ID(rintc_acpi_data[i]->ext_intc_id) == id) {
+			if (idx == j) {
+				*hartid = rintc_acpi_data[i]->hart_id;
+				return 0;
+			}
+			j++;
+		}
+	}
+
+	return -1;
+}
+
+void acpi_get_plic_nr_contexts(u8 id, int *nr_contexts)
+{
+	int i, j = 0;
+
+	for (i = 0; i < nr_rintc; i++) {
+		if (APLIC_PLIC_ID(rintc_acpi_data[i]->ext_intc_id) == id)
+			j++;
+	}
+
+	*nr_contexts = j;
+}
+
+int acpi_get_plic_context(u8 id, u32 idx, int *context_id)
+{
+	int i, j = 0;
+
+	for (i = 0; i < nr_rintc; i++) {
+		if (APLIC_PLIC_ID(rintc_acpi_data[i]->ext_intc_id) == id) {
+			if (idx == j) {
+				*context_id = IDC_CONTEXT_ID(rintc_acpi_data[i]->ext_intc_id);
+				return 0;
+			}
+
+			j++;
+		}
+	}
+
+	return -1;
+}
+
+int acpi_get_imsic_mmio_info(u32 index, struct resource *res)
+{
+	if (index >= nr_rintc)
+		return -1;
+
+	res->start = rintc_acpi_data[index]->imsic_addr;
+	res->end = res->start + rintc_acpi_data[index]->imsic_size - 1;
+	res->flags = IORESOURCE_MEM;
+	return 0;
+}
+
 static int __init riscv_intc_acpi_init(union acpi_subtable_headers *header,
 				       const unsigned long end)
 {
 	struct fwnode_handle *fn;
 	struct acpi_madt_rintc *rintc;
+	int rc;
 
 	rintc = (struct acpi_madt_rintc *)header;
+	rintc_acpi_data[nr_rintc] = kzalloc(sizeof(*rintc_acpi_data[0]), GFP_KERNEL);
+	if (!rintc_acpi_data[nr_rintc])
+		return -ENOMEM;
+
+	rintc_acpi_data[nr_rintc]->ext_intc_id = rintc->ext_intc_id;
+	rintc_acpi_data[nr_rintc]->hart_id = rintc->hart_id;
+	rintc_acpi_data[nr_rintc]->imsic_addr = rintc->imsic_addr;
+	rintc_acpi_data[nr_rintc]->imsic_size = rintc->imsic_size;
+	nr_rintc++;
 
 	/*
 	 * The ACPI MADT will have one INTC for each CPU (or HART)
@@ -218,7 +306,19 @@ static int __init riscv_intc_acpi_init(union acpi_subtable_headers *header,
 		return -ENOMEM;
 	}
 
-	return riscv_intc_init_common(fn);
+	rc = riscv_intc_init_common(fn);
+	if (rc) {
+		irq_domain_free_fwnode(fn);
+		return rc;
+	}
+
+	/*
+	 * MSI controller (IMSIC) in RISC-V is optional. So, unless
+	 * IMSIC is discovered, set system wide MSI support as
+	 * unsupported. Once IMSIC is probed, MSI support will be set.
+	 */
+	pci_no_msi();
+	return 0;
 }
 
 IRQCHIP_ACPI_DECLARE(riscv_intc, ACPI_MADT_TYPE_RINTC, NULL,
-- 
2.39.2