When building with W=1:

    arch/m68k/mac/iop.c:235:13: warning: no previous prototype for ‘iop_init’ [-Wmissing-prototypes]
      235 | void __init iop_init(void)
	  |             ^~~~~~~~
    arch/m68k/mac/via.c:112:13: warning: no previous prototype for ‘via_init’ [-Wmissing-prototypes]
      111 | void __init via_init(void)
	  |             ^~~~~~~~
    arch/m68k/mac/via.c:623:13: warning: no previous prototype for ‘via_init_clock’ [-Wmissing-prototypes]
      593 | void __init via_init_clock(void)
	  |             ^~~~~~~~~~~~~~
    arch/m68k/mac/oss.c:37:13: warning: no previous prototype for ‘oss_init’ [-Wmissing-prototypes]
       37 | void __init oss_init(void)
	  |             ^~~~~~~~
    arch/m68k/mac/psc.c:76:13: warning: no previous prototype for ‘psc_init’ [-Wmissing-prototypes]
       76 | void __init psc_init(void)
	  |             ^~~~~~~~
    arch/m68k/mac/baboon.c:25:13: warning: no previous prototype for ‘baboon_init’ [-Wmissing-prototypes]
       25 | void __init baboon_init(void)
	  |             ^~~~~~~~~~~
    arch/m68k/mac/macboing.c:155:6: warning: no previous prototype for ‘mac_mksound’ [-Wmissing-prototypes]
      155 | void mac_mksound( unsigned int freq, unsigned int length )
	  |      ^~~~~~~~~~~
    arch/m68k/mac/misc.c:608:5: warning: no previous prototype for ‘mac_hwclk’ [-Wmissing-prototypes]
      608 | int mac_hwclk(int op, struct rtc_time *t)
	  |     ^~~~~~~~~

Fix this by introducing a new header file "mac.h" for holding the
prototypes of functions implemented in arch/m68k/mac/.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 arch/m68k/mac/baboon.c   |  2 ++
 arch/m68k/mac/config.c   | 12 ++----------
 arch/m68k/mac/iop.c      |  2 ++
 arch/m68k/mac/mac.h      | 25 +++++++++++++++++++++++++
 arch/m68k/mac/macboing.c |  2 ++
 arch/m68k/mac/misc.c     |  2 ++
 arch/m68k/mac/oss.c      |  2 ++
 arch/m68k/mac/psc.c      |  2 ++
 arch/m68k/mac/via.c      |  2 ++
 9 files changed, 41 insertions(+), 10 deletions(-)
 create mode 100644 arch/m68k/mac/mac.h

diff --git a/arch/m68k/mac/baboon.c b/arch/m68k/mac/baboon.c
index a7d280220662c747..5c97a7058bcdee2e 100644
--- a/arch/m68k/mac/baboon.c
+++ b/arch/m68k/mac/baboon.c
@@ -15,6 +15,8 @@
 #include <asm/macints.h>
 #include <asm/mac_baboon.h>
 
+#include "mac.h"
+
 int baboon_present;
 static volatile struct baboon *baboon;
 
diff --git a/arch/m68k/mac/config.c b/arch/m68k/mac/config.c
index d56affefd5cabeb5..e324410ef239c09f 100644
--- a/arch/m68k/mac/config.c
+++ b/arch/m68k/mac/config.c
@@ -50,22 +50,14 @@
 #include <asm/mac_psc.h>
 #include <asm/config.h>
 
+#include "mac.h"
+
 /* Mac bootinfo struct */
 struct mac_booter_data mac_bi_data;
 
 /* The phys. video addr. - might be bogus on some machines */
 static unsigned long mac_orig_videoaddr;
 
-extern int mac_hwclk(int, struct rtc_time *);
-extern void iop_init(void);
-extern void via_init(void);
-extern void via_init_clock(void);
-extern void oss_init(void);
-extern void psc_init(void);
-extern void baboon_init(void);
-
-extern void mac_mksound(unsigned int, unsigned int);
-
 static void mac_get_model(char *str);
 static void mac_identify(void);
 static void mac_report_hardware(void);
diff --git a/arch/m68k/mac/iop.c b/arch/m68k/mac/iop.c
index 010b3b5ae8e8584a..a92740d530ac4fbe 100644
--- a/arch/m68k/mac/iop.c
+++ b/arch/m68k/mac/iop.c
@@ -119,6 +119,8 @@
 #include <asm/macints.h>
 #include <asm/mac_iop.h>
 
+#include "mac.h"
+
 #ifdef DEBUG
 #define iop_pr_debug(fmt, ...) \
 	printk(KERN_DEBUG "%s: " fmt, __func__, ##__VA_ARGS__)
diff --git a/arch/m68k/mac/mac.h b/arch/m68k/mac/mac.h
new file mode 100644
index 0000000000000000..d3d142cea3b4b911
--- /dev/null
+++ b/arch/m68k/mac/mac.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+struct rtc_time;
+
+/* baboon.c */
+void baboon_init(void);
+
+/* iop.c */
+void iop_init(void);
+
+/* misc.c */
+int mac_hwclk(int op, struct rtc_time *t);
+
+/* macboing.c */
+void mac_mksound(unsigned int freq, unsigned int length);
+
+/* oss.c */
+void oss_init(void);
+
+/* psc.c */
+void psc_init(void);
+
+/* via.c */
+void via_init(void);
+void via_init_clock(void);
diff --git a/arch/m68k/mac/macboing.c b/arch/m68k/mac/macboing.c
index 76431241347682fc..faea2265a540192d 100644
--- a/arch/m68k/mac/macboing.c
+++ b/arch/m68k/mac/macboing.c
@@ -16,6 +16,8 @@
 #include <asm/macintosh.h>
 #include <asm/mac_asc.h>
 
+#include "mac.h"
+
 static int mac_asc_inited;
 /*
  * dumb triangular wave table
diff --git a/arch/m68k/mac/misc.c b/arch/m68k/mac/misc.c
index 65107abc8848232c..4c8f8cbfa05f3404 100644
--- a/arch/m68k/mac/misc.c
+++ b/arch/m68k/mac/misc.c
@@ -25,6 +25,8 @@
 
 #include <asm/machdep.h>
 
+#include "mac.h"
+
 /*
  * Offset between Unix time (1970-based) and Mac time (1904-based). Cuda and PMU
  * times wrap in 2040. If we need to handle later times, the read_time functions
diff --git a/arch/m68k/mac/oss.c b/arch/m68k/mac/oss.c
index 921e6c092f2c6626..1641607f300d981c 100644
--- a/arch/m68k/mac/oss.c
+++ b/arch/m68k/mac/oss.c
@@ -27,6 +27,8 @@
 #include <asm/mac_via.h>
 #include <asm/mac_oss.h>
 
+#include "mac.h"
+
 int oss_present;
 volatile struct mac_oss *oss;
 
diff --git a/arch/m68k/mac/psc.c b/arch/m68k/mac/psc.c
index 0d0965b19c09b439..b4183cf66efef7f5 100644
--- a/arch/m68k/mac/psc.c
+++ b/arch/m68k/mac/psc.c
@@ -26,6 +26,8 @@
 #include <asm/macints.h>
 #include <asm/mac_psc.h>
 
+#include "mac.h"
+
 #define DEBUG_PSC
 
 volatile __u8 *psc;
diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c
index 3d11d6219cdd56da..01e6b0e37f8dd0e8 100644
--- a/arch/m68k/mac/via.c
+++ b/arch/m68k/mac/via.c
@@ -38,6 +38,8 @@
 #include <asm/mac_psc.h>
 #include <asm/mac_oss.h>
 
+#include "mac.h"
+
 volatile __u8 *via1, *via2;
 int rbv_present;
 int via_alt_mapping;
-- 
2.34.1

On Thu, 7 Sep 2023, Geert Uytterhoeven wrote:

> diff --git a/arch/m68k/mac/baboon.c b/arch/m68k/mac/baboon.c
> index a7d280220662c747..5c97a7058bcdee2e 100644
> --- a/arch/m68k/mac/baboon.c
> +++ b/arch/m68k/mac/baboon.c
> @@ -15,6 +15,8 @@
>  #include <asm/macints.h>
>  #include <asm/mac_baboon.h>
>  
> +#include "mac.h"
> +
>  int baboon_present;
>  static volatile struct baboon *baboon;
>  
> diff --git a/arch/m68k/mac/config.c b/arch/m68k/mac/config.c
> index d56affefd5cabeb5..e324410ef239c09f 100644
> --- a/arch/m68k/mac/config.c
> +++ b/arch/m68k/mac/config.c
> @@ -50,22 +50,14 @@
>  #include <asm/mac_psc.h>
>  #include <asm/config.h>
>  
> +#include "mac.h"
> +
>  /* Mac bootinfo struct */
>  struct mac_booter_data mac_bi_data;
>  
>  /* The phys. video addr. - might be bogus on some machines */
>  static unsigned long mac_orig_videoaddr;
>  
> -extern int mac_hwclk(int, struct rtc_time *);
> -extern void iop_init(void);
> -extern void via_init(void);
> -extern void via_init_clock(void);
> -extern void oss_init(void);
> -extern void psc_init(void);
> -extern void baboon_init(void);
> -
> -extern void mac_mksound(unsigned int, unsigned int);
> -
>  static void mac_get_model(char *str);
>  static void mac_identify(void);
>  static void mac_report_hardware(void);
> diff --git a/arch/m68k/mac/iop.c b/arch/m68k/mac/iop.c
> index 010b3b5ae8e8584a..a92740d530ac4fbe 100644
> --- a/arch/m68k/mac/iop.c
> +++ b/arch/m68k/mac/iop.c
> @@ -119,6 +119,8 @@
>  #include <asm/macints.h>
>  #include <asm/mac_iop.h>
>  
> +#include "mac.h"
> +
>  #ifdef DEBUG
>  #define iop_pr_debug(fmt, ...) \
>  	printk(KERN_DEBUG "%s: " fmt, __func__, ##__VA_ARGS__)
> diff --git a/arch/m68k/mac/mac.h b/arch/m68k/mac/mac.h
> new file mode 100644
> index 0000000000000000..d3d142cea3b4b911
> --- /dev/null
> +++ b/arch/m68k/mac/mac.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +struct rtc_time;
> +

I don't think we need a new header file. Related function prototypes 
already have homes in existing header files --

> +/* baboon.c */
> +void baboon_init(void);
> +

this could go into mac_baboon.h

> +/* iop.c */
> +void iop_init(void);
> +

mac_iop.h

> +/* misc.c */
> +int mac_hwclk(int op, struct rtc_time *t);
> +

macintosh.h

> +/* macboing.c */
> +void mac_mksound(unsigned int freq, unsigned int length);
> +

mac_asc.h

> +/* oss.c */
> +void oss_init(void);
> +

mac_oss.h

> +/* psc.c */
> +void psc_init(void);
> +

mac_psc.h

> +/* via.c */
> +void via_init(void);
> +void via_init_clock(void);

mac_via.h

> diff --git a/arch/m68k/mac/macboing.c b/arch/m68k/mac/macboing.c
> index 76431241347682fc..faea2265a540192d 100644
> --- a/arch/m68k/mac/macboing.c
> +++ b/arch/m68k/mac/macboing.c
> @@ -16,6 +16,8 @@
>  #include <asm/macintosh.h>
>  #include <asm/mac_asc.h>
>  
> +#include "mac.h"
> +
>  static int mac_asc_inited;
>  /*
>   * dumb triangular wave table
> diff --git a/arch/m68k/mac/misc.c b/arch/m68k/mac/misc.c
> index 65107abc8848232c..4c8f8cbfa05f3404 100644
> --- a/arch/m68k/mac/misc.c
> +++ b/arch/m68k/mac/misc.c
> @@ -25,6 +25,8 @@
>  
>  #include <asm/machdep.h>
>  
> +#include "mac.h"
> +
>  /*
>   * Offset between Unix time (1970-based) and Mac time (1904-based). Cuda and PMU
>   * times wrap in 2040. If we need to handle later times, the read_time functions
> diff --git a/arch/m68k/mac/oss.c b/arch/m68k/mac/oss.c
> index 921e6c092f2c6626..1641607f300d981c 100644
> --- a/arch/m68k/mac/oss.c
> +++ b/arch/m68k/mac/oss.c
> @@ -27,6 +27,8 @@
>  #include <asm/mac_via.h>
>  #include <asm/mac_oss.h>
>  
> +#include "mac.h"
> +
>  int oss_present;
>  volatile struct mac_oss *oss;
>  
> diff --git a/arch/m68k/mac/psc.c b/arch/m68k/mac/psc.c
> index 0d0965b19c09b439..b4183cf66efef7f5 100644
> --- a/arch/m68k/mac/psc.c
> +++ b/arch/m68k/mac/psc.c
> @@ -26,6 +26,8 @@
>  #include <asm/macints.h>
>  #include <asm/mac_psc.h>
>  
> +#include "mac.h"
> +
>  #define DEBUG_PSC
>  
>  volatile __u8 *psc;
> diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c
> index 3d11d6219cdd56da..01e6b0e37f8dd0e8 100644
> --- a/arch/m68k/mac/via.c
> +++ b/arch/m68k/mac/via.c
> @@ -38,6 +38,8 @@
>  #include <asm/mac_psc.h>
>  #include <asm/mac_oss.h>
>  
> +#include "mac.h"
> +
>  volatile __u8 *via1, *via2;
>  int rbv_present;
>  int via_alt_mapping;
>

Hi Finn,

On Fri, Sep 8, 2023 at 1:44 AM Finn Thain <fthain@linux-m68k.org> wrote:
> On Thu, 7 Sep 2023, Geert Uytterhoeven wrote:
> > --- /dev/null
> > +++ b/arch/m68k/mac/mac.h
> > @@ -0,0 +1,25 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +
> > +struct rtc_time;
> > +
>
> I don't think we need a new header file. Related function prototypes
> already have homes in existing header files --
>
> > +/* baboon.c */
> > +void baboon_init(void);
> > +
>
> this could go into mac_baboon.h
>
> > +/* iop.c */
> > +void iop_init(void);
> > +
>
> mac_iop.h
>
> > +/* misc.c */
> > +int mac_hwclk(int op, struct rtc_time *t);
> > +
>
> macintosh.h
>
> > +/* macboing.c */
> > +void mac_mksound(unsigned int freq, unsigned int length);
> > +
>
> mac_asc.h
>
> > +/* oss.c */
> > +void oss_init(void);
> > +
>
> mac_oss.h
>
> > +/* psc.c */
> > +void psc_init(void);
> > +
>
> mac_psc.h
>
> > +/* via.c */
> > +void via_init(void);
> > +void via_init_clock(void);
>
> mac_via.h

All mac*.h you suggest live under arch/m68k/include/asm/, and are thus
shared with the whole tree, while only the core code under arch/m68k/
needs these definitions.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

On Fri, 8 Sep 2023, Geert Uytterhoeven wrote:

> On Fri, Sep 8, 2023 at 1:44 AM Finn Thain <fthain@linux-m68k.org> wrote:
> > On Thu, 7 Sep 2023, Geert Uytterhoeven wrote:
> > > --- /dev/null
> > > +++ b/arch/m68k/mac/mac.h
> > > @@ -0,0 +1,25 @@
> > > +/* SPDX-License-Identifier: GPL-2.0 */
> > > +
> > > +struct rtc_time;
> > > +
> >
> > I don't think we need a new header file. Related function prototypes
> > already have homes in existing header files --
> >
> > > +/* baboon.c */
> > > +void baboon_init(void);
> > > +
> >
> > this could go into mac_baboon.h
> >
> > > +/* iop.c */
> > > +void iop_init(void);
> > > +
> >
> > mac_iop.h
> >
> > > +/* misc.c */
> > > +int mac_hwclk(int op, struct rtc_time *t);
> > > +
> >
> > macintosh.h
> >
> > > +/* macboing.c */
> > > +void mac_mksound(unsigned int freq, unsigned int length);
> > > +
> >
> > mac_asc.h
> >
> > > +/* oss.c */
> > > +void oss_init(void);
> > > +
> >
> > mac_oss.h
> >
> > > +/* psc.c */
> > > +void psc_init(void);
> > > +
> >
> > mac_psc.h
> >
> > > +/* via.c */
> > > +void via_init(void);
> > > +void via_init_clock(void);
> >
> > mac_via.h
> 
> All mac*.h you suggest live under arch/m68k/include/asm/, and are thus 
> shared with the whole tree, while only the core code under arch/m68k/ 
> needs these definitions.
> 

I guess #include "../mac/mac.h" is expected but
#include "../../m68k/mac/mac.h" is not intended (?)

Hi Finn,

On Sat, Sep 9, 2023 at 12:59 AM Finn Thain <fthain@linux-m68k.org> wrote:
> On Fri, 8 Sep 2023, Geert Uytterhoeven wrote:
> > On Fri, Sep 8, 2023 at 1:44 AM Finn Thain <fthain@linux-m68k.org> wrote:
> > > On Thu, 7 Sep 2023, Geert Uytterhoeven wrote:
> > > > --- /dev/null
> > > > +++ b/arch/m68k/mac/mac.h
> > > > @@ -0,0 +1,25 @@
> > > > +/* SPDX-License-Identifier: GPL-2.0 */
> > > > +
> > > > +struct rtc_time;
> > > > +
> > >
> > > I don't think we need a new header file. Related function prototypes
> > > already have homes in existing header files --
> > >
> > > > +/* baboon.c */
> > > > +void baboon_init(void);
> > > > +
> > >
> > > this could go into mac_baboon.h
> > >
> > > > +/* iop.c */
> > > > +void iop_init(void);
> > > > +
> > >
> > > mac_iop.h
> > >
> > > > +/* misc.c */
> > > > +int mac_hwclk(int op, struct rtc_time *t);
> > > > +
> > >
> > > macintosh.h
> > >
> > > > +/* macboing.c */
> > > > +void mac_mksound(unsigned int freq, unsigned int length);
> > > > +
> > >
> > > mac_asc.h
> > >
> > > > +/* oss.c */
> > > > +void oss_init(void);
> > > > +
> > >
> > > mac_oss.h
> > >
> > > > +/* psc.c */
> > > > +void psc_init(void);
> > > > +
> > >
> > > mac_psc.h
> > >
> > > > +/* via.c */
> > > > +void via_init(void);
> > > > +void via_init_clock(void);
> > >
> > > mac_via.h
> >
> > All mac*.h you suggest live under arch/m68k/include/asm/, and are thus
> > shared with the whole tree, while only the core code under arch/m68k/
> > needs these definitions.
> >
>
> I guess #include "../mac/mac.h" is expected but
> #include "../../m68k/mac/mac.h" is not intended (?)

Yes indeed.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds