I think the header file could avoid redefinition errors.
 at compile time by adding macro definitions.

Signed-off-by: Li zeming <zeming@nfschina.com>
---
 drivers/macintosh/windfarm_pid.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/macintosh/windfarm_pid.h b/drivers/macintosh/windfarm_pid.h
index 83f747dbeafc..9882e90a5071 100644
--- a/drivers/macintosh/windfarm_pid.h
+++ b/drivers/macintosh/windfarm_pid.h
@@ -1,4 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _WINDFARM_PID_H
+#define _WINDFARM_PID_H
+
 /*
  * Windfarm PowerMac thermal control. Generic PID helpers
  *
@@ -82,3 +85,4 @@ struct wf_cpu_pid_state {
 extern void wf_cpu_pid_init(struct wf_cpu_pid_state *st,
 			    struct wf_cpu_pid_param *param);
 extern s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 power, s32 temp);
+#endif
-- 
2.18.2

On Thu, 7 Jul 2022 09:59:49 +0800, Li zeming wrote:
> I think the header file could avoid redefinition errors.
>  at compile time by adding macro definitions.
> 
> 

Applied to powerpc/next.

[1/1] macintosh/windfarm_pid: Add header file macro definition
      https://git.kernel.org/powerpc/c/e3e528d29d13c01289f382a0d3ddb5312ac3dae3

cheers