[PATCH v1 0/8] zorro: Improve handling of pointers in zorro_device_id::driver_data

[PATCH v1 0/8] zorro: Improve handling of pointers in zorro_device_id::driver_data

[Uwe Kleine-König (The Capable Hub)]

Hello,

this series is about improving the handling of pointers in struct
zorro_device_id's driver_data.

While it's ok on all current Linux platforms to store a pointer in an
unsigned long variable, it involves casting that loses type information.
This can be nicely seen in patch #7 where after profiting from patch #6
the compiler notices a missing const.

Preparing for that change, all zorro_device_ids are converted to use
named initializers, which is also a nice cleanup that could stand for
itself, as it improves readability for humans. (That is necessary
because an anonymous union can be initialized by name, but not using a
list initializer.)

My motivation for this series is the CHERI hardware extension. With that
pointers are bigger than longs and thus you cannot store pointers in
zorro_device_id::driver_data. So this series is also about getting
support for CHERI into the mainline, but I hope the clean up effects
mentioned above are justification enough to accept this series.

The dependencies in this series are as follows:

 - Patch #5 depends on #1, #2
 - Patches #7 and #8 depend on patch #6.

So if the ata maintainers agreed to merge their patch #1 via scsi, and
Geert agrees to patch #5 and that it's also merged via scsi, patches #1,
#2, #6 and #7 can go in without further coordination.

Patches #3, #4 and #5 are only about using the same initialization style
for all zorro_device_id and can go in without coordination.

Best regards
Uwe

Uwe Kleine-König (The Capable Hub) (8):
  ata: pata_budda: Use named initializer for zorro_device_id
  scsi: Use named initializer for zorro_device_id
  net: Use named initializer for zorro_device_id arrays
  i2c: icy: Use named initializer for zorro_device_id arrays
  video: fm2fb: Use named initializer for zorro_device_id array
  zorro: Simplify storing pointers in device id struct
  scsi: zorro7xx: Make use of struct zorro_device_id::driver_data_ptr
  video: cirrusfb: Make use of struct zorro_device_id::driver_data_ptr

 drivers/ata/pata_buddha.c             |  8 ++++----
 drivers/i2c/busses/i2c-icy.c          |  4 ++--
 drivers/net/ethernet/8390/hydra.c     |  4 ++--
 drivers/net/ethernet/8390/xsurf100.c  |  4 ++--
 drivers/net/ethernet/8390/zorro8390.c |  6 +++---
 drivers/net/ethernet/amd/a2065.c      |  8 ++++----
 drivers/net/ethernet/amd/ariadne.c    |  4 ++--
 drivers/scsi/a2091.c                  |  6 +++---
 drivers/scsi/gvp11.c                  | 17 ++++++++--------
 drivers/scsi/zorro7xx.c               | 16 +++++++--------
 drivers/scsi/zorro_esp.c              |  2 +-
 drivers/video/fbdev/cirrusfb.c        | 28 +++++++++++++--------------
 drivers/video/fbdev/fm2fb.c           |  6 +++---
 include/linux/mod_devicetable.h       |  6 +++++-
 14 files changed, 62 insertions(+), 57 deletions(-)


base-commit: d387b06f7c15b4639244ad66b4b0900c6a02b430
-- 
2.47.3

[PATCH v1 net-next 3/8] net: Use named initializer for zorro_device_id arrays

[Uwe Kleine-König (The Capable Hub)]

Using named initializers is more explicit and thus easier to parse for a
human.

While touching these arrays, drop explicit zeros from the list terminator.

This change doesn't introduce changes to the compiled zorro_device_id
arrays.

Signed-off-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com>
---
 drivers/net/ethernet/8390/hydra.c     | 4 ++--
 drivers/net/ethernet/8390/xsurf100.c  | 4 ++--
 drivers/net/ethernet/8390/zorro8390.c | 6 +++---
 drivers/net/ethernet/amd/a2065.c      | 8 ++++----
 drivers/net/ethernet/amd/ariadne.c    | 4 ++--
 5 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/8390/hydra.c b/drivers/net/ethernet/8390/hydra.c
index fd9dcdc356e6..9a59915436d2 100644
--- a/drivers/net/ethernet/8390/hydra.c
+++ b/drivers/net/ethernet/8390/hydra.c
@@ -66,8 +66,8 @@ static void hydra_block_output(struct net_device *dev, int count,
 static void hydra_remove_one(struct zorro_dev *z);
 
 static struct zorro_device_id hydra_zorro_tbl[] = {
-    { ZORRO_PROD_HYDRA_SYSTEMS_AMIGANET },
-    { 0 }
+    { .id = ZORRO_PROD_HYDRA_SYSTEMS_AMIGANET },
+    { }
 };
 MODULE_DEVICE_TABLE(zorro, hydra_zorro_tbl);
 
diff --git a/drivers/net/ethernet/8390/xsurf100.c b/drivers/net/ethernet/8390/xsurf100.c
index fe7a74707aa4..370c19aa5fb9 100644
--- a/drivers/net/ethernet/8390/xsurf100.c
+++ b/drivers/net/ethernet/8390/xsurf100.c
@@ -357,8 +357,8 @@ static void xsurf100_remove(struct zorro_dev *zdev)
 }
 
 static const struct zorro_device_id xsurf100_zorro_tbl[] = {
-	{ ZORRO_PROD_INDIVIDUAL_COMPUTERS_X_SURF100, },
-	{ 0 }
+	{ .id = ZORRO_PROD_INDIVIDUAL_COMPUTERS_X_SURF100 },
+	{ }
 };
 
 MODULE_DEVICE_TABLE(zorro, xsurf100_zorro_tbl);
diff --git a/drivers/net/ethernet/8390/zorro8390.c b/drivers/net/ethernet/8390/zorro8390.c
index c24dd4fe7a10..cb1d5ed20874 100644
--- a/drivers/net/ethernet/8390/zorro8390.c
+++ b/drivers/net/ethernet/8390/zorro8390.c
@@ -262,9 +262,9 @@ static void zorro8390_remove_one(struct zorro_dev *z)
 }
 
 static struct zorro_device_id zorro8390_zorro_tbl[] = {
-	{ ZORRO_PROD_VILLAGE_TRONIC_ARIADNE2, },
-	{ ZORRO_PROD_INDIVIDUAL_COMPUTERS_X_SURF, },
-	{ 0 }
+	{ .id = ZORRO_PROD_VILLAGE_TRONIC_ARIADNE2 },
+	{ .id = ZORRO_PROD_INDIVIDUAL_COMPUTERS_X_SURF },
+	{ }
 };
 MODULE_DEVICE_TABLE(zorro, zorro8390_zorro_tbl);
 
diff --git a/drivers/net/ethernet/amd/a2065.c b/drivers/net/ethernet/amd/a2065.c
index ce9445425045..672c4996b30e 100644
--- a/drivers/net/ethernet/amd/a2065.c
+++ b/drivers/net/ethernet/amd/a2065.c
@@ -647,10 +647,10 @@ static void a2065_remove_one(struct zorro_dev *z);
 
 
 static const struct zorro_device_id a2065_zorro_tbl[] = {
-	{ ZORRO_PROD_CBM_A2065_1 },
-	{ ZORRO_PROD_CBM_A2065_2 },
-	{ ZORRO_PROD_AMERISTAR_A2065 },
-	{ 0 }
+	{ .id = ZORRO_PROD_CBM_A2065_1 },
+	{ .id = ZORRO_PROD_CBM_A2065_2 },
+	{ .id = ZORRO_PROD_AMERISTAR_A2065 },
+	{ }
 };
 MODULE_DEVICE_TABLE(zorro, a2065_zorro_tbl);
 
diff --git a/drivers/net/ethernet/amd/ariadne.c b/drivers/net/ethernet/amd/ariadne.c
index fa201da567ed..ec6e7e8c14fe 100644
--- a/drivers/net/ethernet/amd/ariadne.c
+++ b/drivers/net/ethernet/amd/ariadne.c
@@ -693,8 +693,8 @@ static void ariadne_remove_one(struct zorro_dev *z)
 }
 
 static const struct zorro_device_id ariadne_zorro_tbl[] = {
-	{ ZORRO_PROD_VILLAGE_TRONIC_ARIADNE },
-	{ 0 }
+	{ .id = ZORRO_PROD_VILLAGE_TRONIC_ARIADNE },
+	{ }
 };
 MODULE_DEVICE_TABLE(zorro, ariadne_zorro_tbl);
 
-- 
2.47.3

[PATCH v1 6/8] zorro: Simplify storing pointers in device id struct

[Uwe Kleine-König (The Capable Hub)]

Technically it is fine (on all current Linux architectures) to store a
pointer in an unsigned long variable. However this needs explicit
casting which is an easy source for type mismatches.

By replacing the plain unsigned long .driver_data in struct
zorro_device_id by an anonymous union, most of the casting can be
dropped. There is still some implicit casting involved (between a void *
and a driver specific pointer type), but that's better than the approach
to store a pointer in an unsigned long variable as this doesn't lose the
information that the data being pointed to is const.

All users of struct zorro_device_id are initialized in a way that is
compatible with the new definition, so no adaptions are needed there.

Signed-off-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com>
---
 include/linux/mod_devicetable.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 3b0c9a251a2e..2673a1bd82c4 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -640,7 +640,11 @@ struct mdio_device_id {
 
 struct zorro_device_id {
 	__u32 id;			/* Device ID or ZORRO_WILDCARD */
-	kernel_ulong_t driver_data;	/* Data private to the driver */
+	union {
+		/* Data private to the driver */
+		kernel_ulong_t driver_data;
+		const void *driver_data_ptr;
+	};
 };
 
 #define ZORRO_WILDCARD			(0xffffffff)	/* not official */
-- 
2.47.3

Re: [PATCH v1 0/8] zorro: Improve handling of pointers in zorro_device_id::driver_data

[Geert Uytterhoeven]

Hi Uwe,

On Tue, 26 May 2026 at 16:17, Uwe Kleine-König (The Capable Hub)
<u.kleine-koenig@baylibre.com> wrote:
> this series is about improving the handling of pointers in struct
> zorro_device_id's driver_data.
>
> While it's ok on all current Linux platforms to store a pointer in an
> unsigned long variable, it involves casting that loses type information.
> This can be nicely seen in patch #7 where after profiting from patch #6
> the compiler notices a missing const.
>
> Preparing for that change, all zorro_device_ids are converted to use
> named initializers, which is also a nice cleanup that could stand for
> itself, as it improves readability for humans. (That is necessary
> because an anonymous union can be initialized by name, but not using a
> list initializer.)
>
> My motivation for this series is the CHERI hardware extension. With that
> pointers are bigger than longs and thus you cannot store pointers in
> zorro_device_id::driver_data. So this series is also about getting
> support for CHERI into the mainline, but I hope the clean up effects
> mentioned above are justification enough to accept this series.

Thanks for your series!

> The dependencies in this series are as follows:
>
>  - Patch #5 depends on #1, #2

s/5/6/?

>  - Patches #7 and #8 depend on patch #6.
>
> So if the ata maintainers agreed to merge their patch #1 via scsi, and
> Geert agrees to patch #5 and that it's also merged via scsi, patches #1,

s/5/6/?

> #2, #6 and #7 can go in without further coordination.
>
> Patches #3, #4 and #5 are only about using the same initialization style
> for all zorro_device_id and can go in without coordination.
>
> Best regards
> Uwe
>
> Uwe Kleine-König (The Capable Hub) (8):
>   ata: pata_budda: Use named initializer for zorro_device_id
>   scsi: Use named initializer for zorro_device_id
>   net: Use named initializer for zorro_device_id arrays
>   i2c: icy: Use named initializer for zorro_device_id arrays
>   video: fm2fb: Use named initializer for zorro_device_id array
>   zorro: Simplify storing pointers in device id struct
>   scsi: zorro7xx: Make use of struct zorro_device_id::driver_data_ptr
>   video: cirrusfb: Make use of struct zorro_device_id::driver_data_ptr

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

Re: [PATCH v1 net-next 3/8] net: Use named initializer for zorro_device_id arrays

[Geert Uytterhoeven]

On Tue, 26 May 2026 at 16:18, Uwe Kleine-König (The Capable Hub)
<u.kleine-koenig@baylibre.com> wrote:
> Using named initializers is more explicit and thus easier to parse for a
> human.
>
> While touching these arrays, drop explicit zeros from the list terminator.
>
> This change doesn't introduce changes to the compiled zorro_device_id
> arrays.
>
> Signed-off-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com>

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>

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

Re: [PATCH v1 6/8] zorro: Simplify storing pointers in device id struct

[Geert Uytterhoeven]

On Tue, 26 May 2026 at 16:18, Uwe Kleine-König (The Capable Hub)
<u.kleine-koenig@baylibre.com> wrote:
> Technically it is fine (on all current Linux architectures) to store a
> pointer in an unsigned long variable. However this needs explicit
> casting which is an easy source for type mismatches.
>
> By replacing the plain unsigned long .driver_data in struct
> zorro_device_id by an anonymous union, most of the casting can be
> dropped. There is still some implicit casting involved (between a void *
> and a driver specific pointer type), but that's better than the approach
> to store a pointer in an unsigned long variable as this doesn't lose the
> information that the data being pointed to is const.
>
> All users of struct zorro_device_id are initialized in a way that is
> compatible with the new definition, so no adaptions are needed there.
>
> Signed-off-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com>

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

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

Re: [PATCH v1 6/8] zorro: Simplify storing pointers in device id struct

[Max Staudt]

On 5/26/26 11:17 PM, Uwe Kleine-König (The Capable Hub) wrote:
> Technically it is fine (on all current Linux architectures) to store a
> pointer in an unsigned long variable. However this needs explicit
> casting which is an easy source for type mismatches.
> 
> By replacing the plain unsigned long .driver_data in struct
> zorro_device_id by an anonymous union, most of the casting can be
> dropped. There is still some implicit casting involved (between a void *
> and a driver specific pointer type), but that's better than the approach
> to store a pointer in an unsigned long variable as this doesn't lose the
> information that the data being pointed to is const.
> 
> All users of struct zorro_device_id are initialized in a way that is
> compatible with the new definition, so no adaptions are needed there.
> 
> Signed-off-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com>


Thanks Uwe!

Reviewed-by: Max Staudt <max@enpas.org>

Re: [PATCH v1 0/8] zorro: Improve handling of pointers in zorro_device_id::driver_data

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 26 May 2026 16:17:26 +0200 you wrote:
> Hello,
> 
> this series is about improving the handling of pointers in struct
> zorro_device_id's driver_data.
> 
> While it's ok on all current Linux platforms to store a pointer in an
> unsigned long variable, it involves casting that loses type information.
> This can be nicely seen in patch #7 where after profiting from patch #6
> the compiler notices a missing const.
> 
> [...]

Here is the summary with links:
  - [v1,net-next,3/8] net: Use named initializer for zorro_device_id arrays
    https://git.kernel.org/netdev/net-next/c/4933a658369a
  - [v1,6/8] zorro: Simplify storing pointers in device id struct
    (no matching commit)

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html