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@lst.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
[paul.walmsley@sifive.com: split the WFI fix into a separate patch]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

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:

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();
 }

arch/riscv/kernel/sbi.c

+// 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);