linux-kernel - [RFT PATCH 4/4] RISC-V: Parse cpu topology during boot.

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Message-Id: <1543532957-22661-5-git-send-email-atish.patra@wdc.com>
Date:   Thu, 29 Nov 2018 15:09:17 -0800
From:   Atish Patra <atish.patra@....com>
To:     linux-kernel@...r.kernel.org, atish.patra@....com
Subject: [RFT PATCH 4/4] RISC-V: Parse cpu topology during boot.

Currently, there are no topology defined for RISC-V.
Parse the cpu-map node from device tree and setup the
cpu topology.

CPU topology after applying the patch.
$cat /sys/devices/system/cpu/cpu2/topology/core_siblings_list
0-3
$cat /sys/devices/system/cpu/cpu3/topology/core_siblings_list
0-3
$cat /sys/devices/system/cpu/cpu3/topology/physical_package_id
0
$cat /sys/devices/system/cpu/cpu3/topology/core_id
3

Signed-off-by: Atish Patra <atish.patra@....com>
---
 arch/riscv/Kconfig          | 1 +
 arch/riscv/kernel/smpboot.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 55da93f4..b0b1fe1a 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -42,6 +42,7 @@ config RISCV
 	select THREAD_INFO_IN_TASK
 	select RISCV_TIMER
 	select GENERIC_IRQ_MULTI_HANDLER
+	select GENERIC_ARCH_TOPOLOGY if SMP
 	select ARCH_HAS_PTE_SPECIAL

 config MMU
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 18cda0e8..5f435af7 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -16,6 +16,7 @@
  * GNU General Public License for more details.
  */

+#include <linux/arch_topology.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -42,6 +43,7 @@ void *__cpu_up_task_pointer[NR_CPUS];

 void __init smp_prepare_boot_cpu(void)
 {
+	init_cpu_topology();
 }

 void __init smp_prepare_cpus(unsigned int max_cpus)
@@ -115,6 +117,7 @@ asmlinkage void __init smp_callin(void)

 	trap_init();
 	notify_cpu_starting(smp_processor_id());
+	update_siblings_masks(smp_processor_id());
 	set_cpu_online(smp_processor_id(), 1);
 	/*
 	 * Remote TLB flushes are ignored while the CPU is offline, so emit
-- 
2.7.4