linux-kernel - Re: [PATCH 04/12] riscv: cleanup the default power off implementation

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Message-ID: <alpine.DEB.2.21.9999.1910311655320.25874@viisi.sifive.com>
Date:   Thu, 31 Oct 2019 16:56:31 -0700 (PDT)
From:   Paul Walmsley <paul.walmsley@...ive.com>
To:     Christoph Hellwig <hch@....de>
cc:     Palmer Dabbelt <palmer@...ive.com>,
        Damien Le Moal <damien.lemoal@....com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atish.patra@....com>
Subject: Re: [PATCH 04/12] riscv: cleanup the default power off
 implementation

On Mon, 28 Oct 2019, Christoph Hellwig wrote:

> Move the sbi poweroff to a separate function and file that is only
> compiled if CONFIG_SBI is set.  Provide a new default fallback
> power off that just sits in a wfi loop to save some power.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> Reviewed-by: Anup Patel <anup@...infault.org>
> Reviewed-by: Atish Patra <atish.patra@....com>

And here's the other part of this patch, queued for v5.5-rc1.


- Paul


From: Christoph Hellwig <hch@....de>
Date: Mon, 28 Oct 2019 13:10:35 +0100
Subject: [PATCH] riscv: cleanup the default power off implementation

Move the sbi poweroff to a separate function and file that is only
compiled if CONFIG_SBI is set.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Anup Patel <anup@...infault.org>
Reviewed-by: Atish Patra <atish.patra@....com>
[paul.walmsley@...ive.com: split the WFI fix into a separate patch]
Signed-off-by: Paul Walmsley <paul.walmsley@...ive.com>
---
 arch/riscv/kernel/Makefile |  1 +
 arch/riscv/kernel/reset.c  |  2 --
 arch/riscv/kernel/sbi.c    | 17 +++++++++++++++++
 3 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 arch/riscv/kernel/sbi.c

diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 696020ff72db..d8c35fa93cc6 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -41,5 +41,6 @@ obj-$(CONFIG_DYNAMIC_FTRACE)	+= mcount-dyn.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_callchain.o
 obj-$(CONFIG_HAVE_PERF_REGS)	+= perf_regs.o
+obj-$(CONFIG_RISCV_SBI)		+= sbi.o
 
 clean:
diff --git a/arch/riscv/kernel/reset.c b/arch/riscv/kernel/reset.c
index 485be426d9b1..ee5878d968cc 100644
--- a/arch/riscv/kernel/reset.c
+++ b/arch/riscv/kernel/reset.c
@@ -5,11 +5,9 @@
 
 #include <linux/reboot.h>
 #include <linux/pm.h>
-#include <asm/sbi.h>
 
 static void default_power_off(void)
 {
-	sbi_shutdown();
 	while (1)
 		wait_for_interrupt();
 }
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
new file mode 100644
index 000000000000..f6c7c3e82d28
--- /dev/null
+++ b/arch/riscv/kernel/sbi.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/init.h>
+#include <linux/pm.h>
+#include <asm/sbi.h>
+
+static void sbi_power_off(void)
+{
+	sbi_shutdown();
+}
+
+static int __init sbi_init(void)
+{
+	pm_power_off = sbi_power_off;
+	return 0;
+}
+early_initcall(sbi_init);
-- 
2.24.0.rc0