LoongArch: Add multi-processor (SMP) support

LoongArch-based procesors have 4, 8 or 16 cores per package. This patch
adds multi-processor (SMP) support for LoongArch.

Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 39 insertions, 1 deletions

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 03d9b74eb2a9..85ef258d36d2 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -64,6 +64,7 @@ config LOONGARCH
 	select GENERIC_LIB_UCMPDI2
 	select GENERIC_PCI_IOMAP
 	select GENERIC_SCHED_CLOCK
+	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
 	select GPIOLIB
 	select HAVE_ARCH_AUDITSYSCALL
@@ -92,7 +93,7 @@ config LOONGARCH
 	select HAVE_RSEQ
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_TIF_NOHZ
-	select HAVE_VIRT_CPU_ACCOUNTING_GEN
+	select HAVE_VIRT_CPU_ACCOUNTING_GEN if !SMP
 	select IRQ_FORCED_THREADING
 	select IRQ_LOONGARCH_CPU
 	select MODULES_USE_ELF_RELA if MODULES
@@ -297,6 +298,43 @@ config EFI
 	  This enables the kernel to use EFI runtime services that are
 	  available (such as the EFI variable services).
 
+config SMP
+	bool "Multi-Processing support"
+	help
+	  This enables support for systems with more than one CPU. If you have
+	  a system with only one CPU, say N. If you have a system with more
+	  than one CPU, say Y.
+
+	  If you say N here, the kernel will run on uni- and multiprocessor
+	  machines, but will use only one CPU of a multiprocessor machine. If
+	  you say Y here, the kernel will run on many, but not all,
+	  uniprocessor machines. On a uniprocessor machine, the kernel
+	  will run faster if you say N here.
+
+	  See also the SMP-HOWTO available at <http://www.tldp.org/docs.html#howto>.
+
+	  If you don't know what to do here, say N.
+
+config HOTPLUG_CPU
+	bool "Support for hot-pluggable CPUs"
+	depends on SMP
+	select GENERIC_IRQ_MIGRATION
+	help
+	  Say Y here to allow turning CPUs off and on. CPUs can be
+	  controlled through /sys/devices/system/cpu.
+	  (Note: power management support will enable this option
+	    automatically on SMP systems. )
+	  Say N if you want to disable CPU hotplug.
+
+config NR_CPUS
+	int "Maximum number of CPUs (2-256)"
+	range 2 256
+	depends on SMP
+	default "64"
+	help
+	  This allows you to specify the maximum number of CPUs which this
+	  kernel will support.
+
 config FORCE_MAX_ZONEORDER
 	int "Maximum zone order"
 	range 14 64 if PAGE_SIZE_64KB