[PATCH 13/24] RISC-V: ACPI: smpboot: Add ACPI support in smp_setup()

[Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>]

Add function to parse the RINTC structure in
the MADT table and create the required initializations to
enable SMP boot on ACPI based platforms.

Signed-off-by: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
---
 arch/riscv/include/asm/acpi.h |  7 ++++
 arch/riscv/kernel/smpboot.c   | 73 ++++++++++++++++++++++++++++++++++-
 2 files changed, 79 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
index c5cb9f96d404..d1f1e53ec657 100644
--- a/arch/riscv/include/asm/acpi.h
+++ b/arch/riscv/include/asm/acpi.h
@@ -58,6 +58,13 @@ static inline bool acpi_has_cpu_in_madt(void)
 }
 
 static inline void arch_fix_phys_package_id(int num, u32 slot) { }
+
+#ifdef CONFIG_ACPI_NUMA
+int acpi_numa_get_nid(unsigned int cpu);
+#else
+static inline int acpi_numa_get_nid(unsigned int cpu) { return NUMA_NO_NODE; }
+#endif /* CONFIG_ACPI_NUMA */
+
 #endif
 
 #endif /*_ASM_ACPI_H*/
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 26214ddefaa4..e48cf88d0bc1 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -8,6 +8,7 @@
  * Copyright (C) 2017 SiFive
  */
 
+#include <linux/acpi.h>
 #include <linux/arch_topology.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -70,6 +71,73 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 	}
 }
 
+#ifdef CONFIG_ACPI
+static unsigned int cpu_count = 1;
+
+static int __init
+acpi_parse_rintc(union acpi_subtable_headers *header,
+			     const unsigned long end)
+{
+	unsigned long hart;
+	bool found_boot_cpu = false;
+
+	struct acpi_madt_rintc *processor;
+
+	processor = (struct acpi_madt_rintc *)header;
+
+	/* RINTC entry which has !ACPI_MADT_ENABLED is not enabled so skip */
+	if (!(processor->flags & ACPI_MADT_ENABLED))
+		return 0;
+
+	hart = processor->hart_id;
+	if (hart < 0)
+		return 0;
+	if (hart == cpuid_to_hartid_map(0)) {
+		BUG_ON(found_boot_cpu);
+		found_boot_cpu = 1;
+		early_map_cpu_to_node(0, acpi_numa_get_nid(cpu_count));
+		return 0;
+	}
+	if (cpu_count >= NR_CPUS) {
+		pr_warn("Invalid cpuid [%d] for hartid [%lu]\n",
+			cpu_count, hart);
+		return 0;
+	}
+
+	cpuid_to_hartid_map(cpu_count) = hart;
+	early_map_cpu_to_node(cpu_count, acpi_numa_get_nid(cpu_count));
+	cpu_count++;
+	return 0;
+}
+
+static void __init acpi_parse_and_init_cpus(void)
+{
+	int cpuid;
+
+	cpu_set_ops(0);
+	/*
+	 * do a walk of MADT to determine how many CPUs
+	 * we have including disabled CPUs, and get information
+	 * we need for SMP init.
+	 */
+	acpi_table_parse_madt(ACPI_MADT_TYPE_RINTC,
+				      acpi_parse_rintc, 0);
+
+	/*
+	 * NUMA - TODO
+	 */
+
+	for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
+		if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) {
+			cpu_set_ops(cpuid);
+			set_cpu_possible(cpuid, true);
+		}
+	}
+}
+#else
+#define acpi_parse_and_init_cpus(...)	do { } while (0)
+#endif
+
 static void __init of_parse_and_init_cpus(void)
 {
 	struct device_node *dn;
@@ -118,7 +186,10 @@ static void __init of_parse_and_init_cpus(void)
 
 void __init setup_smp(void)
 {
-	of_parse_and_init_cpus();
+	if (acpi_disabled)
+		of_parse_and_init_cpus();
+	else
+		acpi_parse_and_init_cpus();
 }
 
 static int start_secondary_cpu(int cpu, struct task_struct *tidle)
-- 
2.38.0