RISC-V: smpboot: Add ACPI support in setup_smp()

Enable SMP boot on ACPI based platforms by using the RINTC
structures in the MADT table.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230515054928.2079268-13-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
index 3947175..f71ce21 100644 (file)
--- a/arch/riscv/include/asm/acpi.h
+++ b/arch/riscv/include/asm/acpi.h
@@ -64,6 +64,8 @@ struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu);
 u32 get_acpi_id_for_cpu(int cpu);
 int acpi_get_riscv_isa(struct acpi_table_header *table,
                       unsigned int cpu, const char **isa);
+
+static inline int acpi_numa_get_nid(unsigned int cpu) { return NUMA_NO_NODE; }
 #else
 static inline void acpi_init_rintc_map(void) { }
 static inline struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)

diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index a2e6612..67bc5ef 100644 (file)
--- 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 +71,72 @@ 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;
+       static bool found_boot_cpu;
+       struct acpi_madt_rintc *processor = (struct acpi_madt_rintc *)header;
+
+       /*
+        * Each RINTC structure in MADT will have a flag. If ACPI_MADT_ENABLED
+        * bit in the flag is not enabled, it means OS should not try to enable
+        * the cpu to which RINTC belongs.
+        */
+       if (!(processor->flags & ACPI_MADT_ENABLED))
+               return 0;
+
+       if (BAD_MADT_ENTRY(processor, end))
+               return -EINVAL;
+
+       acpi_table_print_madt_entry(&header->common);
+
+       hart = processor->hart_id;
+       if (hart == INVALID_HARTID) {
+               pr_warn("Invalid hartid\n");
+               return 0;
+       }
+
+       if (hart == cpuid_to_hartid_map(0)) {
+               BUG_ON(found_boot_cpu);
+               found_boot_cpu = true;
+               early_map_cpu_to_node(0, acpi_numa_get_nid(cpu_count));
+               return 0;
+       }
+
+       if (cpu_count >= NR_CPUS) {
+               pr_warn("NR_CPUS is too small for the number of ACPI tables.\n");
+               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);
+
+       acpi_table_parse_madt(ACPI_MADT_TYPE_RINTC, acpi_parse_rintc, 0);
+
+       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 +185,10 @@ 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)