[PATCH V3 10/20] RISC-V: smpboot: Add ACPI support in smp_setup()

Sunil V L
2023-03-03T13:38:50Z

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>
---
arch/riscv/kernel/smpboot.c | 72 ++++++++++++++++++++++++++++++++++++-
1 file changed, 71 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 26214ddefaa4..27047322d3bb 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 +71,72 @@ 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, NUMA_NO_NODE);
+ 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, NUMA_NO_NODE);
+ 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)
--
2.34.1