[PATCH v6 00/26] Non-const bitfield helpers

[PATCH v6 00/26] Non-const bitfield helpers

[Geert Uytterhoeven]

	Hi all,

<linux/bitfield.h> contains various helpers for accessing bitfields, as
typically used in hardware registers for memory-mapped I/O blocks.
These helpers ensure type safety, and deduce automatically shift values
from mask values, avoiding mistakes due to inconsistent shifts and
masks, and leading to a reduction in source code size.

The existing FIELD_{GET,PREP}() macros are limited to compile-time
constants.  However, it is very common to prepare or extract bitfield
elements where the bitfield mask is not a compile-time constant (e.g. it
comes from a table, or is created by shifting a compile-time constant).
To avoid this limitation, the AT91 clock driver introduced its own
field_{prep,get}() macros.  During the past four years, these have been
copied to multiple drivers, and more copies are on their way[1], leading
to the obvious review comment "please move this to <linux/bitfield.h>".

Hence this series
  1. Takes preparatory steps in drivers definining local
     field_{get,prep}() macros (patches 1-11),
  2. Introduces __FIELD_{PREP,GET}() helpers to avoid clang W=1 warnings
     (patch 12),
  3. Makes field_{prep,get}() available for general use (patch 13),
  4. Converts drivers with local variants to the common helpers (patches
     14-24),
  5. Converts a few Renesas drivers to the existing FIELD_{GET,PREP}()
     and the new field_{get,prep}() helpers (patches 25-26).

Alternatives would be to use the typed {u*,be*,le*,...}_{get,encode}_bits()
macros instead (which currently do not work with non-constant masks
either, and the first attempt to change that generates much worse code),
or to store the low bit and width of the mask instead (which would
require changing all code that passes masks directly, and also generates
worse code).

Changes compared to v5[2]:
  - Add Acked-by, Reviewed-by,
  - Update sunxi rawnand driver in linux-next,
  - Align \,
  - Add Return sections to kerneldoc,
  - Document field_{get,prep} in top comment block,
  - New patch to add less-checking __FIELD_{GET,PREP}() helpers,
  - Use less-checking __FIELD_{GET,PREP}() to avoid build issues with
    clang and W=1.

Changes compared to v4[3]:
  - Add preparatory patches to #undef field_{get,prep}() in individual
    drivers before defining local variants,
  - Update new smi330 IIO IMU driver in linux-next,
  - Add Acked-by,
  - Document that mask must be non-zero,
  - Document typical usage pattern,
  - Recommend using FIELD_{PREP,GET}() directly to ensure compile-time
    constant masks,
  - Check BITS_PER_TYPE(mask) instead of sizeof(mask),
  - Wire field_{get,prep}() to FIELD_{GET,PREP}() when mask is
    constant, to improve type checking,
  - Extract conversion of individual drivers into separate patches.

Changes compared to v3[4]:
  - Update recently introduced FIELD_MODIFY() macro,
  - Add Acked-by,
  - Rebase on top of commit 7c68005a46108ffa ("crypto: qat - relocate
    power management debugfs helper APIs") in v6.17-rc1,
  - Convert more recently introduced upstream copies:
      - drivers/edac/ie31200_edac.c
      - drivers/iio/dac/ad3530r.c

Changes compared to v2[5]:
  - New patch "[PATCH v3 1/4] bitfield: Drop underscores from macro
    parameters",
  - Add Acked-by,
  - Drop underscores from macro parameters,
  - Use __auto_type where possible,
  - Correctly cast reg to the mask type,
  - Introduces __val and __reg intermediates to simplify the actual
    operation,
  - Drop unneeded parentheses,
  - Clarify having both FIELD_{GET,PREP}() and field_{get,prep}(),

Changes compared to v1[6]:
  - Cast val resp. reg to the mask type,
  - Fix 64-bit use on 32-bit architectures,
  - Convert new upstream users:
      - drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c
      - drivers/gpio/gpio-aspeed.c
      - drivers/iio/temperature/mlx90614.c
      - drivers/pinctrl/nuvoton/pinctrl-ma35.c
      - sound/usb/mixer_quirks.c
  - Convert new user queued in renesas-devel for v6.15:
      - drivers/soc/renesas/rz-sysc.c
  - Drop the last 14 RFC patches.
    They can be updated/resubmitted/applied later.

In the meantime, two more copies ended up in the IIO and MTD trees and
in linux-next (commit 89cba586b8b4cde0 ("iio: imu: smi330: Add driver"
in next-20251021 and later, commits 6fc2619af1eb6f59 ("mtd: rawnand:
sunxi: rework pattern found registers") and d21b4338159ff7d7 ("mtd:
rawnand: sunxi: introduce ecc_mode_mask in sunxi_nfc_caps") in
next-20251029 and later).  As these commits are not yet upstream, any
updates (patches 10, 11, 23 and 24) for these drivers cannot be applied
with the rest of this series yet.

Yury kindly offered to take the lionshare of this series through his
bitmap tree, thanks for that!
I am fine with that, if he would also provide an immutable branch + tag,
which I can merge into the Renesas tree before taking patches 25 and 26
myself.  Once that tag has been merged in subsystem trees or upstream, I
plan to update and resend actual conversions (see patches 4-17 in
v1[6]).

To avoid build issues in linux-next, the IIO resp. MTD maintainers
should:
  1. Apply patch 10 resp. 11 now, and
  2. Apply patch 23 resp. 24 later, either after
       a. merging the immutable branch/tag, or
       b. the new helpers in <linux/bitfield.h> are upstream,

Note that there is also a minor conflict with linux-next due to the
removal of an include file from drivers/gpio/gpio-aspeed.c.

Thanks!

[1] Work-in-progress new copies posted during the last few months (there
    may be more):
      - "[PATCH v2 3/3] gpio: gpio-ltc4283: Add support for the LTC4283 Swap Controller"
	https://lore.kernel.org/20250903-ltc4283-support-v2-3-6bce091510bf@analog.com
      - "[PATCH v7 15/24] media: i2c: add Maxim GMSL2/3 serializer and deserializer framework"
	https://lore.kernel.org/20250718152500.2656391-16-demonsingur@gmail.com
[2] "[PATCH v5 00/23] Non-const bitfield helpers"
    https://lore.kernel.org/all/cover.1761588465.git.geert+renesas@glider.be
[3] "[PATCH v4 0/4] Non-const bitfield helpers"
    https://lore.kernel.org/cover.1760696560.git.geert+renesas@glider.be
[4] "[PATCH v3 0/4] Non-const bitfield helpers"
    https://lore.kernel.org/all/cover.1739540679.git.geert+renesas@glider.be
[5] "[PATCH v2 0/3] Non-const bitfield helpers"
    https://lore.kernel.org/all/cover.1738329458.git.geert+renesas@glider.be
[6] "[PATCH 00/17] Non-const bitfield helper conversions"
    https://lore.kernel.org/all/cover.1637592133.git.geert+renesas@glider.be

Geert Uytterhoeven (26):
  clk: at91: pmc: #undef field_{get,prep}() before definition
  crypto: qat - #undef field_get() before local definition
  EDAC/ie31200: #undef field_get() before local definition
  gpio: aspeed: #undef field_{get,prep}() before local definition
  iio: dac: ad3530r: #undef field_prep() before local definition
  iio: mlx90614: #undef field_{get,prep}() before local definition
  pinctrl: ma35: #undef field_{get,prep}() before local definition
  soc: renesas: rz-sysc: #undef field_get() before local definition
  ALSA: usb-audio: #undef field_{get,prep}() before local definition
  [-next] iio: imu: smi330: #undef field_{get,prep}() before definition
  [-next] mtd: rawnand: sunxi: #undef field_{get,prep}() before local
    definition
  bitfield: Add less-checking __FIELD_{GET,PREP}()
  bitfield: Add non-constant field_{prep,get}() helpers
  clk: at91: Convert to common field_{get,prep}() helpers
  crypto: qat - convert to common field_get() helper
  EDAC/ie31200: Convert to common field_get() helper
  gpio: aspeed: Convert to common field_{get,prep}() helpers
  iio: dac: Convert to common field_prep() helper
  iio: mlx90614: Convert to common field_{get,prep}() helpers
  pinctrl: ma35: Convert to common field_{get,prep}() helpers
  soc: renesas: rz-sysc: Convert to common field_get() helper
  ALSA: usb-audio: Convert to common field_{get,prep}() helpers
  [-next] iio: imu: smi330: Convert to common field_{get,prep}() helpers
  [-next] mtd: rawnand: sunxi: Convert to common field_{get,prep}()
    helpers
  clk: renesas: Use bitfield helpers
  soc: renesas: Use bitfield helpers

 drivers/clk/at91/clk-peripheral.c             |  1 +
 drivers/clk/at91/pmc.h                        |  3 -
 drivers/clk/renesas/clk-div6.c                |  6 +-
 drivers/clk/renesas/rcar-gen3-cpg.c           | 15 +--
 drivers/clk/renesas/rcar-gen4-cpg.c           |  9 +-
 .../intel/qat/qat_common/adf_pm_dbgfs_utils.c |  8 +-
 drivers/edac/ie31200_edac.c                   |  4 +-
 drivers/gpio/gpio-aspeed.c                    |  5 +-
 drivers/iio/dac/ad3530r.c                     |  3 -
 drivers/iio/imu/smi330/smi330_core.c          |  4 -
 drivers/iio/temperature/mlx90614.c            |  5 +-
 drivers/mtd/nand/raw/sunxi_nand.c             |  4 -
 drivers/pinctrl/nuvoton/pinctrl-ma35.c        |  4 -
 drivers/soc/renesas/renesas-soc.c             |  4 +-
 drivers/soc/renesas/rz-sysc.c                 |  3 +-
 include/linux/bitfield.h                      | 95 +++++++++++++++++--
 sound/usb/mixer_quirks.c                      |  4 -
 17 files changed, 106 insertions(+), 71 deletions(-)

-- 
2.43.0

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

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[PATCH v6 01/26] clk: at91: pmc: #undef field_{get,prep}() before definition

[Geert Uytterhoeven]

Prepare for the advent of globally available common field_get() and
field_prep() macros by undefining the symbols before defining local
variants.  This prevents redefinition warnings from the C preprocessor
when introducing the common macros later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
v6:
  - Add Acked-by,

v5:
  - New.
---
 drivers/clk/at91/pmc.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h
index 5daa32c4cf2540d7..78a87d31463e98b0 100644
--- a/drivers/clk/at91/pmc.h
+++ b/drivers/clk/at91/pmc.h
@@ -117,7 +117,9 @@ struct at91_clk_pms {
 	unsigned int parent;
 };
 
+#undef field_get
 #define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
+#undef field_prep
 #define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
 
 #define ndck(a, s) (a[s - 1].id + 1)
-- 
2.43.0


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[PATCH v6 02/26] crypto: qat - #undef field_get() before local definition

[Geert Uytterhoeven]

Prepare for the advent of a globally available common field_get() macro
by undefining the symbol before defining a local variant.  This prevents
redefinition warnings from the C preprocessor when introducing the common
macro later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
---
v6:
  - Add Acked-by,

v5:
  - New.
---
 drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c b/drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c
index 69295a9ddf0ac92f..6186fafb4a7b0dab 100644
--- a/drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c
+++ b/drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c
@@ -11,6 +11,7 @@
  * pm_scnprint_table(), making it not compile time constant, so the compile
  * asserts from FIELD_GET() or u32_get_bits() won't be fulfilled.
  */
+#undef field_get
 #define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
 
 #define PM_INFO_MAX_KEY_LEN	21
-- 
2.43.0


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[PATCH v6 03/26] EDAC/ie31200: #undef field_get() before local definition

[Geert Uytterhoeven]

Prepare for the advent of a globally available common field_get() macro
by undefining the symbol before defining a local variant.  This prevents
redefinition warnings from the C preprocessor when introducing the common
macro later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - New.
---
 drivers/edac/ie31200_edac.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/edac/ie31200_edac.c b/drivers/edac/ie31200_edac.c
index 5a080ab65476dacf..72290f430126c631 100644
--- a/drivers/edac/ie31200_edac.c
+++ b/drivers/edac/ie31200_edac.c
@@ -140,6 +140,7 @@
 #define IE31200_CAPID0_ECC		BIT(1)
 
 /* Non-constant mask variant of FIELD_GET() */
+#undef field_get
 #define field_get(_mask, _reg)  (((_reg) & (_mask)) >> (ffs(_mask) - 1))
 
 static int nr_channels;
-- 
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[PATCH v6 04/26] gpio: aspeed: #undef field_{get,prep}() before local definition

[Geert Uytterhoeven]

Prepare for the advent of globally available common field_get() and
field_prep() macros by undefining the symbols before defining local
variants.  This prevents redefinition warnings from the C preprocessor
when introducing the common macros later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
v6:
  - Add Acked-by,

v5:
  - New.
---
 drivers/gpio/gpio-aspeed.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c
index 7953a9c4e36d7550..ef4ccaf74a5b379e 100644
--- a/drivers/gpio/gpio-aspeed.c
+++ b/drivers/gpio/gpio-aspeed.c
@@ -32,7 +32,9 @@
 #include "gpiolib.h"
 
 /* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
+#undef field_get
 #define field_get(_mask, _reg)	(((_reg) & (_mask)) >> (ffs(_mask) - 1))
+#undef field_prep
 #define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))
 
 #define GPIO_G7_IRQ_STS_BASE 0x100
-- 
2.43.0


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[PATCH v6 05/26] iio: dac: ad3530r: #undef field_prep() before local definition

[Geert Uytterhoeven]

Prepare for the advent of a globally available common field_prep() macro
by undefining the symbol before defining a local variant.  This prevents
redefinition warnings from the C preprocessor when introducing the common
macro later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - New.
---
 drivers/iio/dac/ad3530r.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/dac/ad3530r.c b/drivers/iio/dac/ad3530r.c
index 6134613777b8e1d4..5684d11137f29948 100644
--- a/drivers/iio/dac/ad3530r.c
+++ b/drivers/iio/dac/ad3530r.c
@@ -54,6 +54,7 @@
 #define AD3531R_MAX_CHANNELS			4
 
 /* Non-constant mask variant of FIELD_PREP() */
+#undef field_prep
 #define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))
 
 enum ad3530r_mode {
-- 
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[PATCH v6 06/26] iio: mlx90614: #undef field_{get,prep}() before local definition

[Geert Uytterhoeven]

Prepare for the advent of globally available common field_get() and
field_prep() macros by undefining the symbols before defining local
variants.  This prevents redefinition warnings from the C preprocessor
when introducing the common macros later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - New.
---
 drivers/iio/temperature/mlx90614.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c
index 8a44a00bfd5ece38..de5615fdb396aa3c 100644
--- a/drivers/iio/temperature/mlx90614.c
+++ b/drivers/iio/temperature/mlx90614.c
@@ -69,7 +69,9 @@
 #define MLX90614_CONST_FIR 0x7 /* Fixed value for FIR part of low pass filter */
 
 /* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
+#undef field_get
 #define field_get(_mask, _reg)	(((_reg) & (_mask)) >> (ffs(_mask) - 1))
+#undef field_prep
 #define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))
 
 struct mlx_chip_info {
-- 
2.43.0


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[PATCH v6 07/26] pinctrl: ma35: #undef field_{get,prep}() before local definition

[Geert Uytterhoeven]

Prepare for the advent of globally available common field_get() and
field_prep() macros by undefining the symbols before defining local
variants.  This prevents redefinition warnings from the C preprocessor
when introducing the common macros later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
---
v6:
  - Add Acked-by,

v5:
  - New.
---
 drivers/pinctrl/nuvoton/pinctrl-ma35.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pinctrl/nuvoton/pinctrl-ma35.c b/drivers/pinctrl/nuvoton/pinctrl-ma35.c
index cdad01d68a37e365..925dd717c9deead5 100644
--- a/drivers/pinctrl/nuvoton/pinctrl-ma35.c
+++ b/drivers/pinctrl/nuvoton/pinctrl-ma35.c
@@ -82,7 +82,9 @@
 #define MVOLT_3300			1
 
 /* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
+#undef field_get
 #define field_get(_mask, _reg)	(((_reg) & (_mask)) >> (ffs(_mask) - 1))
+#undef field_prep
 #define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))
 
 static const char * const gpio_group_name[] = {
-- 
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[PATCH v6 08/26] soc: renesas: rz-sysc: #undef field_get() before local definition

[Geert Uytterhoeven]

Prepare for the advent of a globally available common field_get() macro
by undefining the symbol before defining a local variant.  This prevents
redefinition warnings from the C preprocessor when introducing the common
macro later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - New.
---
 drivers/soc/renesas/rz-sysc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/soc/renesas/rz-sysc.c b/drivers/soc/renesas/rz-sysc.c
index 9f79e299e6f41641..b9880085d3634065 100644
--- a/drivers/soc/renesas/rz-sysc.c
+++ b/drivers/soc/renesas/rz-sysc.c
@@ -16,6 +16,7 @@
 
 #include "rz-sysc.h"
 
+#undef field_get
 #define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
 
 /**
-- 
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[PATCH v6 09/26] ALSA: usb-audio: #undef field_{get,prep}() before local definition

[Geert Uytterhoeven]

Prepare for the advent of globally available common field_get() and
field_prep() macros by undefining the symbols before defining local
variants.  This prevents redefinition warnings from the C preprocessor
when introducing the common macros later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
v6:
  - Add Acked-by,

v5:
  - New.
---
 sound/usb/mixer_quirks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index 828af3095b86ee0a..713a8498b975e1ac 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -3312,7 +3312,9 @@ static int snd_bbfpro_controls_create(struct usb_mixer_interface *mixer)
 #define RME_DIGIFACE_INVERT BIT(31)
 
 /* Nonconst helpers */
+#undef field_get
 #define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
+#undef field_prep
 #define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
 
 static int snd_rme_digiface_write_reg(struct snd_kcontrol *kcontrol, int item, u16 mask, u16 val)
-- 
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[PATCH -next v6 10/26] iio: imu: smi330: #undef field_{get,prep}() before definition

[Geert Uytterhoeven]

Prepare for the advent of globally available common field_get() and
field_prep() macros by undefining the symbols before defining local
variants.  This prevents redefinition warnings from the C preprocessor
when introducing the common macros later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - New.
---
 drivers/iio/imu/smi330/smi330_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iio/imu/smi330/smi330_core.c b/drivers/iio/imu/smi330/smi330_core.c
index d9178725ade3da83..a79964fe68fadf47 100644
--- a/drivers/iio/imu/smi330/smi330_core.c
+++ b/drivers/iio/imu/smi330/smi330_core.c
@@ -68,7 +68,9 @@
 #define SMI330_SOFT_RESET_DELAY 2000
 
 /* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
+#undef field_get
 #define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
+#undef field_prep
 #define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
 
 #define SMI330_ACCEL_CHANNEL(_axis) {					\
-- 
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[PATCH -next v6 11/26] mtd: rawnand: sunxi: #undef field_{get,prep}() before local definition

[Geert Uytterhoeven]

Prepare for the advent of globally available common field_get() and
field_prep() macros by undefining the symbols before defining local
variants.  This prevents redefinition warnings from the C preprocessor
when introducing the common macros later.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - New.
---
 drivers/mtd/nand/raw/sunxi_nand.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index 031ab651c5a83b74..9dcdc93734cbff39 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -30,7 +30,9 @@
 #include <linux/reset.h>
 
 /* non compile-time field get/prep */
+#undef field_get
 #define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
+#undef field_prep
 #define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
 
 #define NFC_REG_CTL		0x0000
-- 
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[PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Geert Uytterhoeven]

The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned
(long) long" _mask types.  For constant masks, that condition is usually
met, as GENMASK() yields an UL value.  The few places where the
constant mask is stored in an intermediate variable were fixed by
changing the variable type to u64 (see e.g. [1] and [2]).

However, for non-constant masks, smaller unsigned types should be valid,
too, but currently lead to "result of comparison of constant
18446744073709551615 with expression of type ... is always
false"-warnings with clang and W=1.

Hence refactor the __BF_FIELD_CHECK() helper, and factor out
__FIELD_{GET,PREP}().  The later lack the single problematic check, but
are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
used in the fully non-const variants later.

[1] commit 5c667d5a5a3ec166 ("clk: sp7021: Adjust width of _m in
    HWM_FIELD_PREP()")
[2] commit cfd6fb45cfaf46fa ("crypto: ccree - avoid out-of-range
    warnings from clang")

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - New.

Alternatively, FIELD_{GET,PREP}() could be duplicated, with the second
parameter of __BF_FIELD_CHECK() changed from "0ULL" resp. "_reg" to
"_mask":

    #define __FIELD_PREP(_mask, _val)                                      \
	   ({                                                              \
		   __BF_FIELD_CHECK(_mask, _mask, _val, "__FIELD_PREP: "); \
		   ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask);   \
	   })

    #define __FIELD_GET(_mask, _reg)                                       \
	   ({                                                              \
		   __BF_FIELD_CHECK(_mask, _mask, 0U, "__FIELD_GET: ");    \
		   (typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \
	   })

But I think that is less intuitive, and prevents defining
FIELD_{GET,PREP}() using __FIELD_{GET,PREP}().
---
 include/linux/bitfield.h | 36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index 5355f8f806a97974..bf8e0ae4b5b41038 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h
@@ -60,7 +60,7 @@
 
 #define __bf_cast_unsigned(type, x)	((__unsigned_scalar_typeof(type))(x))
 
-#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx)			\
+#define __BF_FIELD_CHECK_MASK(_mask, _val, _pfx)			\
 	({								\
 		BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask),		\
 				 _pfx "mask is not constant");		\
@@ -69,13 +69,33 @@
 				 ~((_mask) >> __bf_shf(_mask)) &	\
 					(0 + (_val)) : 0,		\
 				 _pfx "value too large for the field"); \
-		BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) >	\
-				 __bf_cast_unsigned(_reg, ~0ull),	\
-				 _pfx "type of reg too small for mask"); \
 		__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) +			\
 					      (1ULL << __bf_shf(_mask))); \
 	})
 
+#define __BF_FIELD_CHECK_REG(mask, reg, pfx)				\
+	BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) >		\
+			 __bf_cast_unsigned(reg, ~0ull),		\
+			 pfx "type of reg too small for mask")
+
+#define __BF_FIELD_CHECK(mask, reg, val, pfx)				\
+	({								\
+		__BF_FIELD_CHECK_MASK(mask, val, pfx);			\
+		__BF_FIELD_CHECK_REG(mask, reg, pfx);			\
+	})
+
+#define __FIELD_PREP(mask, val, pfx)					\
+	({								\
+		__BF_FIELD_CHECK_MASK(mask, val, pfx);			\
+		((typeof(mask))(val) << __bf_shf(mask)) & (mask);	\
+	})
+
+#define __FIELD_GET(mask, reg, pfx)					\
+	({								\
+		__BF_FIELD_CHECK_MASK(mask, 0U, pfx);			\
+		(typeof(mask))(((reg) & (mask)) >> __bf_shf(mask));	\
+	})
+
 /**
  * FIELD_MAX() - produce the maximum value representable by a field
  * @_mask: shifted mask defining the field's length and position
@@ -112,8 +132,8 @@
  */
 #define FIELD_PREP(_mask, _val)						\
 	({								\
-		__BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: ");	\
-		((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask);	\
+		__BF_FIELD_CHECK_REG(_mask, 0ULL, "FIELD_PREP: ");	\
+		__FIELD_PREP(_mask, _val, "FIELD_PREP: ");		\
 	})
 
 #define __BF_CHECK_POW2(n)	BUILD_BUG_ON_ZERO(((n) & ((n) - 1)) != 0)
@@ -152,8 +172,8 @@
  */
 #define FIELD_GET(_mask, _reg)						\
 	({								\
-		__BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: ");	\
-		(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask));	\
+		__BF_FIELD_CHECK_REG(_mask, _reg, "FIELD_GET: ");	\
+		__FIELD_GET(_mask, _reg, "FIELD_GET: ");		\
 	})
 
 /**
-- 
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[PATCH v6 13/26] bitfield: Add non-constant field_{prep,get}() helpers

[Geert Uytterhoeven]

The existing FIELD_{GET,PREP}() macros are limited to compile-time
constants.  However, it is very common to prepare or extract bitfield
elements where the bitfield mask is not a compile-time constant.

To avoid this limitation, the AT91 clock driver and several other
drivers already have their own non-const field_{prep,get}() macros.
Make them available for general use by adding them to
<linux/bitfield.h>, and improve them slightly:
  1. Avoid evaluating macro parameters more than once,
  2. Replace "ffs() - 1" by "__ffs()",
  3. Support 64-bit use on 32-bit architectures,
  4. Wire field_{get,prep}() to FIELD_{GET,PREP}() when mask is
     actually constant.

This is deliberately not merged into the existing FIELD_{GET,PREP}()
macros, as people expressed the desire to keep stricter variants for
increased safety, or for performance critical paths.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Crt Mori <cmo@melexis.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Acked-by: Richard Genoud <richard.genoud@bootlin.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
---
v6:
  - Align \,
  - Add Return sections to kerneldoc,
  - Add Reviewed-by,
  - Document field_{get,prep} in top comment block,
  - Use less-checking __FIELD_{GET,PREP}() to avoid build issues with
    clang and W=1:
    https://lore.kernel.org/all/202510281335.UpSLYJG9-lkp@intel.com
    https://lore.kernel.org/all/202510281414.DnejZh4n-lkp@intel.com
    https://lore.kernel.org/all/202510281304.RK3J3c3t-lkp@intel.com

v5:
  - Add Acked-by,
  - Split off changes outside <linux/bitfield.h>,
  - Document that mask must be non-zero,
  - Document typical usage pattern,
  - Recommend using FIELD_{PREP,GET}() directly to ensure compile-time
    constant masks,
  - Check BITS_PER_TYPE(mask) instead of sizeof(mask),
  - Wire field_{get,prep}() to FIELD_{GET,PREP}() when mask is
    constant, to improve type checking.

v4:
  - Add Acked-by,
  - Rebase on top of commit 7c68005a46108ffa ("crypto: qat - relocate
    power management debugfs helper APIs") in v6.17-rc1,
  - Convert more recently introduced upstream copies:
      - drivers/edac/ie31200_edac.c
      - drivers/iio/dac/ad3530r.c

v3:
  - Add Acked-by,
  - Drop underscores from macro parameters,
  - Use __auto_type where possible,
  - Correctly cast reg to the mask type,
  - Introduces __val and __reg intermediates to simplify the actual
    operation,
  - Drop unneeded parentheses,
  - Clarify having both FIELD_{GET,PREP}() and field_{get,prep}(),

v2:
  - Cast val resp. reg to the mask type,
  - Fix 64-bit use on 32-bit architectures,
  - Convert new upstream users:
      - drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c
      - drivers/gpio/gpio-aspeed.c
      - drivers/iio/temperature/mlx90614.c
      - drivers/pinctrl/nuvoton/pinctrl-ma35.c
      - sound/usb/mixer_quirks.c
  - Convert new user queued in renesas-devel for v6.15:
      - drivers/soc/renesas/rz-sysc.c
---
 include/linux/bitfield.h | 59 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index bf8e0ae4b5b41038..f92e18c9629a59c6 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h
@@ -17,6 +17,7 @@
  * FIELD_{GET,PREP} macros take as first parameter shifted mask
  * from which they extract the base mask and shift amount.
  * Mask must be a compilation time constant.
+ * field_{get,prep} are variants that take a non-const mask.
  *
  * Example:
  *
@@ -240,4 +241,62 @@ __MAKE_OP(64)
 #undef __MAKE_OP
 #undef ____MAKE_OP
 
+#define __field_prep(mask, val)						\
+	({								\
+		__auto_type __mask = (mask);				\
+		typeof(mask) __val = (val);				\
+		unsigned int __shift = BITS_PER_TYPE(mask) <= 32 ?	\
+				       __ffs(__mask) : __ffs64(__mask);	\
+		(__val << __shift) & __mask;				\
+	})
+
+#define __field_get(mask, reg)						\
+	({								\
+		__auto_type __mask = (mask);				\
+		typeof(mask) __reg =  (reg);				\
+		unsigned int __shift = BITS_PER_TYPE(mask) <= 32 ?	\
+				       __ffs(__mask) : __ffs64(__mask);	\
+		(__reg & __mask) >> __shift;				\
+	})
+
+/**
+ * field_prep() - prepare a bitfield element
+ * @mask: shifted mask defining the field's length and position, must be
+ *        non-zero
+ * @val:  value to put in the field
+ *
+ * Return: field value masked and shifted to its final destination
+ *
+ * field_prep() masks and shifts up the value.  The result should be
+ * combined with other fields of the bitfield using logical OR.
+ * Unlike FIELD_PREP(), @mask is not limited to a compile-time constant.
+ * Typical usage patterns are a value stored in a table, or calculated by
+ * shifting a constant by a variable number of bits.
+ * If you want to ensure that @mask is a compile-time constant, please use
+ * FIELD_PREP() directly instead.
+ */
+#define field_prep(mask, val)						\
+	(__builtin_constant_p(mask) ? __FIELD_PREP(mask, val, "field_prep: ") \
+				    : __field_prep(mask, val))
+
+/**
+ * field_get() - extract a bitfield element
+ * @mask: shifted mask defining the field's length and position, must be
+ *        non-zero
+ * @reg:  value of entire bitfield
+ *
+ * Return: extracted field value
+ *
+ * field_get() extracts the field specified by @mask from the
+ * bitfield passed in as @reg by masking and shifting it down.
+ * Unlike FIELD_GET(), @mask is not limited to a compile-time constant.
+ * Typical usage patterns are a value stored in a table, or calculated by
+ * shifting a constant by a variable number of bits.
+ * If you want to ensure that @mask is a compile-time constant, please use
+ * FIELD_GET() directly instead.
+ */
+#define field_get(mask, reg)						\
+	(__builtin_constant_p(mask) ? __FIELD_GET(mask, reg, "field_get: ") \
+				    : __field_get(mask, reg))
+
 #endif
-- 
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[PATCH v6 14/26] clk: at91: Convert to common field_{get,prep}() helpers

[Geert Uytterhoeven]

Drop the driver-specific field_get() and field_prep() macros, in favor
of the globally available variants from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
v6:
  - No changes,

v5:
  - Extracted from "bitfield: Add non-constant field_{prep,get}()
    helpers".
---
 drivers/clk/at91/clk-peripheral.c | 1 +
 drivers/clk/at91/pmc.h            | 5 -----
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/clk/at91/clk-peripheral.c b/drivers/clk/at91/clk-peripheral.c
index e700f40fd87f9327..e7208c47268b6397 100644
--- a/drivers/clk/at91/clk-peripheral.c
+++ b/drivers/clk/at91/clk-peripheral.c
@@ -3,6 +3,7 @@
  *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
  */
 
+#include <linux/bitfield.h>
 #include <linux/bitops.h>
 #include <linux/clk-provider.h>
 #include <linux/clkdev.h>
diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h
index 78a87d31463e98b0..543d7aee8d248cdb 100644
--- a/drivers/clk/at91/pmc.h
+++ b/drivers/clk/at91/pmc.h
@@ -117,11 +117,6 @@ struct at91_clk_pms {
 	unsigned int parent;
 };
 
-#undef field_get
-#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
-#undef field_prep
-#define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
-
 #define ndck(a, s) (a[s - 1].id + 1)
 #define nck(a) (a[ARRAY_SIZE(a) - 1].id + 1)
 
-- 
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[PATCH v6 15/26] crypto: qat - convert to common field_get() helper

[Geert Uytterhoeven]

Drop the driver-specific field_get() macro, in favor of the globally
available variant from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
---
v6:
  - Add Acked-by,

v5:
  - Extracted from "bitfield: Add non-constant field_{prep,get}()
    helpers".
---
 drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c b/drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c
index 6186fafb4a7b0dab..4ccc94ed9493a64c 100644
--- a/drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c
+++ b/drivers/crypto/intel/qat/qat_common/adf_pm_dbgfs_utils.c
@@ -1,19 +1,12 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright(c) 2025 Intel Corporation */
+#include <linux/bitfield.h>
 #include <linux/bitops.h>
 #include <linux/sprintf.h>
 #include <linux/string_helpers.h>
 
 #include "adf_pm_dbgfs_utils.h"
 
-/*
- * This is needed because a variable is used to index the mask at
- * pm_scnprint_table(), making it not compile time constant, so the compile
- * asserts from FIELD_GET() or u32_get_bits() won't be fulfilled.
- */
-#undef field_get
-#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
-
 #define PM_INFO_MAX_KEY_LEN	21
 
 static int pm_scnprint_table(char *buff, const struct pm_status_row *table,
-- 
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[PATCH v6 16/26] EDAC/ie31200: Convert to common field_get() helper

[Geert Uytterhoeven]

Drop the driver-specific field_get() macro, in favor of the globally
available variant from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - Extracted from "bitfield: Add non-constant field_{prep,get}()
    helpers".
---
 drivers/edac/ie31200_edac.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/edac/ie31200_edac.c b/drivers/edac/ie31200_edac.c
index 72290f430126c631..dfc9a9cecd74207d 100644
--- a/drivers/edac/ie31200_edac.c
+++ b/drivers/edac/ie31200_edac.c
@@ -44,6 +44,7 @@
  * but lo_hi_readq() ensures that we are safe across all e3-1200 processors.
  */
 
+#include <linux/bitfield.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/pci.h>
@@ -139,10 +140,6 @@
 #define IE31200_CAPID0_DDPCD		BIT(6)
 #define IE31200_CAPID0_ECC		BIT(1)
 
-/* Non-constant mask variant of FIELD_GET() */
-#undef field_get
-#define field_get(_mask, _reg)  (((_reg) & (_mask)) >> (ffs(_mask) - 1))
-
 static int nr_channels;
 static struct pci_dev *mci_pdev;
 static int ie31200_registered = 1;
-- 
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[PATCH v6 17/26] gpio: aspeed: Convert to common field_{get,prep}() helpers

[Geert Uytterhoeven]

Drop the driver-specific field_get() and field_prep() macros, in favor
of the globally available variants from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - Extracted from "bitfield: Add non-constant field_{prep,get}()
    helpers".
---
 drivers/gpio/gpio-aspeed.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c
index ef4ccaf74a5b379e..3da999334971d501 100644
--- a/drivers/gpio/gpio-aspeed.c
+++ b/drivers/gpio/gpio-aspeed.c
@@ -5,6 +5,7 @@
  * Joel Stanley <joel@jms.id.au>
  */
 
+#include <linux/bitfield.h>
 #include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/gpio/aspeed.h>
@@ -31,12 +32,6 @@
 #include <linux/gpio/consumer.h>
 #include "gpiolib.h"
 
-/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
-#undef field_get
-#define field_get(_mask, _reg)	(((_reg) & (_mask)) >> (ffs(_mask) - 1))
-#undef field_prep
-#define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))
-
 #define GPIO_G7_IRQ_STS_BASE 0x100
 #define GPIO_G7_IRQ_STS_OFFSET(x) (GPIO_G7_IRQ_STS_BASE + (x) * 0x4)
 #define GPIO_G7_CTRL_REG_BASE 0x180
-- 
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[PATCH v6 18/26] iio: dac: Convert to common field_prep() helper

[Geert Uytterhoeven]

Drop the driver-specific field_prep() macro, in favor of the globally
available variant from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
v6:
  - No changes,

v5:
  - Extracted from "bitfield: Add non-constant field_{prep,get}()
    helpers".
---
 drivers/iio/dac/ad3530r.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/iio/dac/ad3530r.c b/drivers/iio/dac/ad3530r.c
index 5684d11137f29948..b97b46090d808ee7 100644
--- a/drivers/iio/dac/ad3530r.c
+++ b/drivers/iio/dac/ad3530r.c
@@ -53,10 +53,6 @@
 #define AD3530R_MAX_CHANNELS			8
 #define AD3531R_MAX_CHANNELS			4
 
-/* Non-constant mask variant of FIELD_PREP() */
-#undef field_prep
-#define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))
-
 enum ad3530r_mode {
 	AD3530R_NORMAL_OP,
 	AD3530R_POWERDOWN_1K,
-- 
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[PATCH v6 19/26] iio: mlx90614: Convert to common field_{get,prep}() helpers

[Geert Uytterhoeven]

Drop the driver-specific field_get() and field_prep() macros, in favor
of the globally available variants from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Crt Mori <cmo@melexis.com>
---
v6:
  - No changes,

v5:
  - Extracted from "bitfield: Add non-constant field_{prep,get}()
    helpers".
---
 drivers/iio/temperature/mlx90614.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c
index de5615fdb396aa3c..1ad21b73e1b44cb0 100644
--- a/drivers/iio/temperature/mlx90614.c
+++ b/drivers/iio/temperature/mlx90614.c
@@ -22,6 +22,7 @@
  * the "wakeup" GPIO is not given, power management will be disabled.
  */
 
+#include <linux/bitfield.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/gpio/consumer.h>
@@ -68,12 +69,6 @@
 #define MLX90614_CONST_SCALE 20 /* Scale in milliKelvin (0.02 * 1000) */
 #define MLX90614_CONST_FIR 0x7 /* Fixed value for FIR part of low pass filter */
 
-/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
-#undef field_get
-#define field_get(_mask, _reg)	(((_reg) & (_mask)) >> (ffs(_mask) - 1))
-#undef field_prep
-#define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))
-
 struct mlx_chip_info {
 	/* EEPROM offsets with 16-bit data, MSB first */
 	/* emissivity correction coefficient */
-- 
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[PATCH v6 20/26] pinctrl: ma35: Convert to common field_{get,prep}() helpers

[Geert Uytterhoeven]

Drop the driver-specific field_get() and field_prep() macros, in favor
of the globally available variants from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
v6:
  - Add Reviewed-by,

v5:
  - Extracted from "bitfield: Add non-constant field_{prep,get}()
    helpers".
---
 drivers/pinctrl/nuvoton/pinctrl-ma35.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/pinctrl/nuvoton/pinctrl-ma35.c b/drivers/pinctrl/nuvoton/pinctrl-ma35.c
index 925dd717c9deead5..8d71dc53cc1de1f8 100644
--- a/drivers/pinctrl/nuvoton/pinctrl-ma35.c
+++ b/drivers/pinctrl/nuvoton/pinctrl-ma35.c
@@ -81,12 +81,6 @@
 #define MVOLT_1800			0
 #define MVOLT_3300			1
 
-/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
-#undef field_get
-#define field_get(_mask, _reg)	(((_reg) & (_mask)) >> (ffs(_mask) - 1))
-#undef field_prep
-#define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))
-
 static const char * const gpio_group_name[] = {
 	"gpioa", "gpiob", "gpioc", "gpiod", "gpioe", "gpiof", "gpiog",
 	"gpioh", "gpioi", "gpioj", "gpiok", "gpiol", "gpiom", "gpion",
-- 
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[PATCH v6 21/26] soc: renesas: rz-sysc: Convert to common field_get() helper

[Geert Uytterhoeven]

Drop the driver-specific field_get() macro, in favor of the globally
available variant from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - Extracted from "bitfield: Add non-constant field_{prep,get}()
    helpers".
---
 drivers/soc/renesas/rz-sysc.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/soc/renesas/rz-sysc.c b/drivers/soc/renesas/rz-sysc.c
index b9880085d3634065..73eaf8b9d69f7208 100644
--- a/drivers/soc/renesas/rz-sysc.c
+++ b/drivers/soc/renesas/rz-sysc.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2024 Renesas Electronics Corp.
  */
 
+#include <linux/bitfield.h>
 #include <linux/cleanup.h>
 #include <linux/io.h>
 #include <linux/mfd/syscon.h>
@@ -16,9 +17,6 @@
 
 #include "rz-sysc.h"
 
-#undef field_get
-#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
-
 /**
  * struct rz_sysc - RZ SYSC private data structure
  * @base: SYSC base address
-- 
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[PATCH v6 22/26] ALSA: usb-audio: Convert to common field_{get,prep}() helpers

[Geert Uytterhoeven]

Drop the driver-specific field_get() and field_prep() macros, in favor
of the globally available variants from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
v6:
  - Add Acked-by,

v5:
  - Extracted from "bitfield: Add non-constant field_{prep,get}()
    helpers".
---
 sound/usb/mixer_quirks.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index 713a8498b975e1ac..6eee89cbc0867f2b 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -3311,12 +3311,6 @@ static int snd_bbfpro_controls_create(struct usb_mixer_interface *mixer)
 #define RME_DIGIFACE_REGISTER(reg, mask) (((reg) << 16) | (mask))
 #define RME_DIGIFACE_INVERT BIT(31)
 
-/* Nonconst helpers */
-#undef field_get
-#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
-#undef field_prep
-#define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
-
 static int snd_rme_digiface_write_reg(struct snd_kcontrol *kcontrol, int item, u16 mask, u16 val)
 {
 	struct usb_mixer_elem_list *list = snd_kcontrol_chip(kcontrol);
-- 
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[PATCH -next v6 23/26] iio: imu: smi330: Convert to common field_{get,prep}() helpers

[Geert Uytterhoeven]

Drop the driver-specific field_get() and field_prep() macros, in favor
of the globally available variants from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - New.
---
 drivers/iio/imu/smi330/smi330_core.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/iio/imu/smi330/smi330_core.c b/drivers/iio/imu/smi330/smi330_core.c
index a79964fe68fadf47..83e0dff5d973d046 100644
--- a/drivers/iio/imu/smi330/smi330_core.c
+++ b/drivers/iio/imu/smi330/smi330_core.c
@@ -67,12 +67,6 @@
 #define SMI330_CHIP_ID 0x42
 #define SMI330_SOFT_RESET_DELAY 2000
 
-/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
-#undef field_get
-#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
-#undef field_prep
-#define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
-
 #define SMI330_ACCEL_CHANNEL(_axis) {					\
 	.type = IIO_ACCEL,						\
 	.modified = 1,							\
-- 
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[PATCH -next v6 24/26] mtd: rawnand: sunxi: Convert to common field_{get,prep}() helpers

[Geert Uytterhoeven]

Drop the driver-specific field_get() and field_prep() macros, in favor
of the globally available variants from <linux/bitfield.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - New.
---
 drivers/mtd/nand/raw/sunxi_nand.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index 9dcdc93734cbff39..e66adfcca7cd63fb 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -29,12 +29,6 @@
 #include <linux/iopoll.h>
 #include <linux/reset.h>
 
-/* non compile-time field get/prep */
-#undef field_get
-#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
-#undef field_prep
-#define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
-
 #define NFC_REG_CTL		0x0000
 #define NFC_REG_ST		0x0004
 #define NFC_REG_INT		0x0008
-- 
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[PATCH v6 25/26] clk: renesas: Use bitfield helpers

[Geert Uytterhoeven]

Use the FIELD_{GET,PREP}() and field_{get,prep}() helpers for const
respective non-const bitfields, instead of open-coding the same
operations.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - No changes,

v4:
  - No changes,

v3:
  - No changes,

v2:
  - Rebase on top of commit 470e3f0d0b1529ab ("clk: renesas: rcar-gen4:
    Introduce R-Car Gen4 CPG driver").
---
 drivers/clk/renesas/clk-div6.c      |  6 +++---
 drivers/clk/renesas/rcar-gen3-cpg.c | 15 +++++----------
 drivers/clk/renesas/rcar-gen4-cpg.c |  9 +++------
 3 files changed, 11 insertions(+), 19 deletions(-)

diff --git a/drivers/clk/renesas/clk-div6.c b/drivers/clk/renesas/clk-div6.c
index 3abd6e5400aded6a..f7b827b5e9b2dd32 100644
--- a/drivers/clk/renesas/clk-div6.c
+++ b/drivers/clk/renesas/clk-div6.c
@@ -7,6 +7,7 @@
  * Contact: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
  */
 
+#include <linux/bitfield.h>
 #include <linux/clk-provider.h>
 #include <linux/init.h>
 #include <linux/io.h>
@@ -171,8 +172,7 @@ static u8 cpg_div6_clock_get_parent(struct clk_hw *hw)
 	if (clock->src_mask == 0)
 		return 0;
 
-	hw_index = (readl(clock->reg) & clock->src_mask) >>
-		   __ffs(clock->src_mask);
+	hw_index = field_get(clock->src_mask, readl(clock->reg));
 	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
 		if (clock->parents[i] == hw_index)
 			return i;
@@ -191,7 +191,7 @@ static int cpg_div6_clock_set_parent(struct clk_hw *hw, u8 index)
 	if (index >= clk_hw_get_num_parents(hw))
 		return -EINVAL;
 
-	src = clock->parents[index] << __ffs(clock->src_mask);
+	src = field_prep(clock->src_mask, clock->parents[index]);
 	writel((readl(clock->reg) & ~clock->src_mask) | src, clock->reg);
 	return 0;
 }
diff --git a/drivers/clk/renesas/rcar-gen3-cpg.c b/drivers/clk/renesas/rcar-gen3-cpg.c
index 10ae20489df9abd8..b954278ddd9d8aa8 100644
--- a/drivers/clk/renesas/rcar-gen3-cpg.c
+++ b/drivers/clk/renesas/rcar-gen3-cpg.c
@@ -54,10 +54,8 @@ static unsigned long cpg_pll_clk_recalc_rate(struct clk_hw *hw,
 {
 	struct cpg_pll_clk *pll_clk = to_pll_clk(hw);
 	unsigned int mult;
-	u32 val;
 
-	val = readl(pll_clk->pllcr_reg) & CPG_PLLnCR_STC_MASK;
-	mult = (val >> __ffs(CPG_PLLnCR_STC_MASK)) + 1;
+	mult = FIELD_GET(CPG_PLLnCR_STC_MASK, readl(pll_clk->pllcr_reg)) + 1;
 
 	return parent_rate * mult * pll_clk->fixed_mult;
 }
@@ -94,7 +92,7 @@ static int cpg_pll_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 
 	val = readl(pll_clk->pllcr_reg);
 	val &= ~CPG_PLLnCR_STC_MASK;
-	val |= (mult - 1) << __ffs(CPG_PLLnCR_STC_MASK);
+	val |= FIELD_PREP(CPG_PLLnCR_STC_MASK, mult - 1);
 	writel(val, pll_clk->pllcr_reg);
 
 	for (i = 1000; i; i--) {
@@ -176,11 +174,7 @@ static unsigned long cpg_z_clk_recalc_rate(struct clk_hw *hw,
 					   unsigned long parent_rate)
 {
 	struct cpg_z_clk *zclk = to_z_clk(hw);
-	unsigned int mult;
-	u32 val;
-
-	val = readl(zclk->reg) & zclk->mask;
-	mult = 32 - (val >> __ffs(zclk->mask));
+	unsigned int mult = 32 - field_get(zclk->mask, readl(zclk->reg));
 
 	return DIV_ROUND_CLOSEST_ULL((u64)parent_rate * mult,
 				     32 * zclk->fixed_div);
@@ -231,7 +225,8 @@ static int cpg_z_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 	if (readl(zclk->kick_reg) & CPG_FRQCRB_KICK)
 		return -EBUSY;
 
-	cpg_reg_modify(zclk->reg, zclk->mask, (32 - mult) << __ffs(zclk->mask));
+	cpg_reg_modify(zclk->reg, zclk->mask,
+		       field_prep(zclk->mask, 32 - mult));
 
 	/*
 	 * Set KICK bit in FRQCRB to update hardware setting and wait for
diff --git a/drivers/clk/renesas/rcar-gen4-cpg.c b/drivers/clk/renesas/rcar-gen4-cpg.c
index fb9a876aaba5cbcd..db3a0b8ef2b936bb 100644
--- a/drivers/clk/renesas/rcar-gen4-cpg.c
+++ b/drivers/clk/renesas/rcar-gen4-cpg.c
@@ -279,11 +279,7 @@ static unsigned long cpg_z_clk_recalc_rate(struct clk_hw *hw,
 					   unsigned long parent_rate)
 {
 	struct cpg_z_clk *zclk = to_z_clk(hw);
-	unsigned int mult;
-	u32 val;
-
-	val = readl(zclk->reg) & zclk->mask;
-	mult = 32 - (val >> __ffs(zclk->mask));
+	unsigned int mult = 32 - field_get(zclk->mask, readl(zclk->reg));
 
 	return DIV_ROUND_CLOSEST_ULL((u64)parent_rate * mult,
 				     32 * zclk->fixed_div);
@@ -334,7 +330,8 @@ static int cpg_z_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 	if (readl(zclk->kick_reg) & CPG_FRQCRB_KICK)
 		return -EBUSY;
 
-	cpg_reg_modify(zclk->reg, zclk->mask, (32 - mult) << __ffs(zclk->mask));
+	cpg_reg_modify(zclk->reg, zclk->mask,
+		       field_prep(zclk->mask, 32 - mult));
 
 	/*
 	 * Set KICK bit in FRQCRB to update hardware setting and wait for
-- 
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[PATCH v6 26/26] soc: renesas: Use bitfield helpers

[Geert Uytterhoeven]

Use the field_get() helper, instead of open-coding the same operation.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v6:
  - No changes,

v5:
  - No changes,

v4:
  - No changes,

v3:
  - No changes,

v2:
  - Drop RFC, as a dependency was applied.
---
 drivers/soc/renesas/renesas-soc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/renesas/renesas-soc.c b/drivers/soc/renesas/renesas-soc.c
index 1eb52356b996bdd7..ee4f17bb4db45db7 100644
--- a/drivers/soc/renesas/renesas-soc.c
+++ b/drivers/soc/renesas/renesas-soc.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2014-2016 Glider bvba
  */
 
+#include <linux/bitfield.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
@@ -524,8 +525,7 @@ static int __init renesas_soc_init(void)
 							   eshi, eslo);
 		}
 
-		if (soc->id &&
-		    ((product & id->mask) >> __ffs(id->mask)) != soc->id) {
+		if (soc->id && field_get(id->mask, product) != soc->id) {
 			pr_warn("SoC mismatch (product = 0x%x)\n", product);
 			ret = -ENODEV;
 			goto free_soc_dev_attr;
-- 
2.43.0


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Re: [PATCH -next v6 24/26] mtd: rawnand: sunxi: Convert to common field_{get,prep}() helpers

[Miquel Raynal]

Hello Geert,

On 06/11/2025 at 14:34:12 +01, Geert Uytterhoeven <geert+renesas@glider.be> wrote:

> Drop the driver-specific field_get() and field_prep() macros, in favor
> of the globally available variants from <linux/bitfield.h>.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> v6:
>   - New.

Thanks for preemptively handling this case!

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>

Thansk,
Miquèl

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Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Andy Shevchenko]

On Thu, Nov 06, 2025 at 02:34:00PM +0100, Geert Uytterhoeven wrote:
> The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned
> (long) long" _mask types.  For constant masks, that condition is usually
> met, as GENMASK() yields an UL value.  The few places where the
> constant mask is stored in an intermediate variable were fixed by
> changing the variable type to u64 (see e.g. [1] and [2]).
> 
> However, for non-constant masks, smaller unsigned types should be valid,
> too, but currently lead to "result of comparison of constant
> 18446744073709551615 with expression of type ... is always
> false"-warnings with clang and W=1.
> 
> Hence refactor the __BF_FIELD_CHECK() helper, and factor out
> __FIELD_{GET,PREP}().  The later lack the single problematic check, but
> are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
> used in the fully non-const variants later.
> 
> [1] commit 5c667d5a5a3ec166 ("clk: sp7021: Adjust width of _m in
>     HWM_FIELD_PREP()")
> [2] commit cfd6fb45cfaf46fa ("crypto: ccree - avoid out-of-range
>     warnings from clang")


Also can be made as

Link: https://git.kernel.org/torvalds/c/5c667d5a5a3ec166 [1]

The positive effect that one may click that on Git Web.
Ideally, of course, would be an additional parses on Git Web kernel.org uses to
parse that standard "commit ...()" notation to add the respective HREF link.

> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

...

> +	BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) >		\
> +			 __bf_cast_unsigned(reg, ~0ull),		\
> +			 pfx "type of reg too small for mask")

Perhaps we may convert this (and others?) to static_assert():s at some point?


-- 
With Best Regards,
Andy Shevchenko



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Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Geert Uytterhoeven]

Hi Andy,

On Thu, 6 Nov 2025 at 15:44, Andy Shevchenko
<andriy.shevchenko@intel.com> wrote:
> On Thu, Nov 06, 2025 at 02:34:00PM +0100, Geert Uytterhoeven wrote:
> > The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned
> > (long) long" _mask types.  For constant masks, that condition is usually
> > met, as GENMASK() yields an UL value.  The few places where the
> > constant mask is stored in an intermediate variable were fixed by
> > changing the variable type to u64 (see e.g. [1] and [2]).
> >
> > However, for non-constant masks, smaller unsigned types should be valid,
> > too, but currently lead to "result of comparison of constant
> > 18446744073709551615 with expression of type ... is always
> > false"-warnings with clang and W=1.
> >
> > Hence refactor the __BF_FIELD_CHECK() helper, and factor out
> > __FIELD_{GET,PREP}().  The later lack the single problematic check, but
> > are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
> > used in the fully non-const variants later.
> >
> > [1] commit 5c667d5a5a3ec166 ("clk: sp7021: Adjust width of _m in
> >     HWM_FIELD_PREP()")
> > [2] commit cfd6fb45cfaf46fa ("crypto: ccree - avoid out-of-range
> >     warnings from clang")
>
> Also can be made as
>
> Link: https://git.kernel.org/torvalds/c/5c667d5a5a3ec166 [1]

Nooooh... torvalds might click on it, and complain ;-)

> > +     BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) >               \
> > +                      __bf_cast_unsigned(reg, ~0ull),                \
> > +                      pfx "type of reg too small for mask")
>
> Perhaps we may convert this (and others?) to static_assert():s at some point?

Nick tried that before, without success:
https://lore.kernel.org/all/CAKwvOdm_prtk1UQNJQGidZm44Lk582S3p=of0y46+rVjnSgXJg@mail.gmail.com

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

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Re: [PATCH v6 01/26] clk: at91: pmc: #undef field_{get,prep}() before definition

[Claudiu Beznea]

On 11/6/25 15:33, Geert Uytterhoeven wrote:
> Prepare for the advent of globally available common field_get() and
> field_prep() macros by undefining the symbols before defining local
> variants.  This prevents redefinition warnings from the C preprocessor
> when introducing the common macros later.
> 
> Suggested-by: Yury Norov <yury.norov@gmail.com>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Acked-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>

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Re: [PATCH v6 08/26] soc: renesas: rz-sysc: #undef field_get() before local definition

[Claudiu Beznea]

On 11/6/25 15:33, Geert Uytterhoeven wrote:
> Prepare for the advent of a globally available common field_get() macro
> by undefining the symbol before defining a local variant.  This prevents
> redefinition warnings from the C preprocessor when introducing the common
> macro later.
> 
> Suggested-by: Yury Norov <yury.norov@gmail.com>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Reviewed-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>


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Re: [PATCH v6 21/26] soc: renesas: rz-sysc: Convert to common field_get() helper

[Claudiu Beznea]

On 11/6/25 15:34, Geert Uytterhoeven wrote:
> Drop the driver-specific field_get() macro, in favor of the globally
> available variant from <linux/bitfield.h>.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Reviewed-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

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Re: [PATCH v6 14/26] clk: at91: Convert to common field_{get,prep}() helpers

[Claudiu Beznea]

On 11/6/25 15:34, Geert Uytterhoeven wrote:
> Drop the driver-specific field_get() and field_prep() macros, in favor
> of the globally available variants from <linux/bitfield.h>.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>


Acked-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>

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Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Yury Norov]

On Thu, Nov 06, 2025 at 04:44:31PM +0200, Andy Shevchenko wrote:
> On Thu, Nov 06, 2025 at 02:34:00PM +0100, Geert Uytterhoeven wrote:
> > The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned
> > (long) long" _mask types.  For constant masks, that condition is usually
> > met, as GENMASK() yields an UL value.  The few places where the
> > constant mask is stored in an intermediate variable were fixed by
> > changing the variable type to u64 (see e.g. [1] and [2]).
> > 
> > However, for non-constant masks, smaller unsigned types should be valid,
> > too, but currently lead to "result of comparison of constant
> > 18446744073709551615 with expression of type ... is always
> > false"-warnings with clang and W=1.
> > 
> > Hence refactor the __BF_FIELD_CHECK() helper, and factor out
> > __FIELD_{GET,PREP}().  The later lack the single problematic check, but
> > are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
> > used in the fully non-const variants later.
> > 
> > [1] commit 5c667d5a5a3ec166 ("clk: sp7021: Adjust width of _m in
> >     HWM_FIELD_PREP()")
> > [2] commit cfd6fb45cfaf46fa ("crypto: ccree - avoid out-of-range
> >     warnings from clang")
> 
> 
> Also can be made as
> 
> Link: https://git.kernel.org/torvalds/c/5c667d5a5a3ec166 [1]
> 
> The positive effect that one may click that on Git Web.
> Ideally, of course, would be an additional parses on Git Web kernel.org uses to
> parse that standard "commit ...()" notation to add the respective HREF link.

Those flying over Atlantic or cruising cross Caribbean would disagree. :)
 
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> 
> ...
> 
> > +	BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) >		\
> > +			 __bf_cast_unsigned(reg, ~0ull),		\
> > +			 pfx "type of reg too small for mask")
> 
> Perhaps we may convert this (and others?) to static_assert():s at some point?
> 
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 

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Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Andy Shevchenko]

On Thu, Nov 06, 2025 at 11:01:39AM -0500, Yury Norov wrote:
> On Thu, Nov 06, 2025 at 04:44:31PM +0200, Andy Shevchenko wrote:
> > On Thu, Nov 06, 2025 at 02:34:00PM +0100, Geert Uytterhoeven wrote:
> > > The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned
> > > (long) long" _mask types.  For constant masks, that condition is usually
> > > met, as GENMASK() yields an UL value.  The few places where the
> > > constant mask is stored in an intermediate variable were fixed by
> > > changing the variable type to u64 (see e.g. [1] and [2]).
> > > 
> > > However, for non-constant masks, smaller unsigned types should be valid,
> > > too, but currently lead to "result of comparison of constant
> > > 18446744073709551615 with expression of type ... is always
> > > false"-warnings with clang and W=1.
> > > 
> > > Hence refactor the __BF_FIELD_CHECK() helper, and factor out
> > > __FIELD_{GET,PREP}().  The later lack the single problematic check, but
> > > are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
> > > used in the fully non-const variants later.
> > > 
> > > [1] commit 5c667d5a5a3ec166 ("clk: sp7021: Adjust width of _m in
> > >     HWM_FIELD_PREP()")
> > > [2] commit cfd6fb45cfaf46fa ("crypto: ccree - avoid out-of-range
> > >     warnings from clang")
> > 
> > 
> > Also can be made as
> > 
> > Link: https://git.kernel.org/torvalds/c/5c667d5a5a3ec166 [1]
> > 
> > The positive effect that one may click that on Git Web.
> > Ideally, of course, would be an additional parses on Git Web kernel.org uses to
> > parse that standard "commit ...()" notation to add the respective HREF link.
> 
> Those flying over Atlantic or cruising cross Caribbean would disagree. :)

They won't. The purpose of these Links is described in the above commit message.
Even they read the commit message before clicking.

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Andy Shevchenko



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Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Andy Shevchenko]

On Thu, Nov 06, 2025 at 03:49:03PM +0100, Geert Uytterhoeven wrote:
> Hi Andy,
> 
> On Thu, 6 Nov 2025 at 15:44, Andy Shevchenko
> <andriy.shevchenko@intel.com> wrote:
> > On Thu, Nov 06, 2025 at 02:34:00PM +0100, Geert Uytterhoeven wrote:
> > > The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned
> > > (long) long" _mask types.  For constant masks, that condition is usually
> > > met, as GENMASK() yields an UL value.  The few places where the
> > > constant mask is stored in an intermediate variable were fixed by
> > > changing the variable type to u64 (see e.g. [1] and [2]).
> > >
> > > However, for non-constant masks, smaller unsigned types should be valid,
> > > too, but currently lead to "result of comparison of constant
> > > 18446744073709551615 with expression of type ... is always
> > > false"-warnings with clang and W=1.
> > >
> > > Hence refactor the __BF_FIELD_CHECK() helper, and factor out
> > > __FIELD_{GET,PREP}().  The later lack the single problematic check, but
> > > are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
> > > used in the fully non-const variants later.
> > >
> > > [1] commit 5c667d5a5a3ec166 ("clk: sp7021: Adjust width of _m in
> > >     HWM_FIELD_PREP()")
> > > [2] commit cfd6fb45cfaf46fa ("crypto: ccree - avoid out-of-range
> > >     warnings from clang")
> >
> > Also can be made as
> >
> > Link: https://git.kernel.org/torvalds/c/5c667d5a5a3ec166 [1]
> 
> Nooooh... torvalds might click on it, and complain ;-)

See my reply to Yury.

> > > +     BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) >               \
> > > +                      __bf_cast_unsigned(reg, ~0ull),                \
> > > +                      pfx "type of reg too small for mask")
> >
> > Perhaps we may convert this (and others?) to static_assert():s at some point?
> 
> Nick tried that before, without success:
> https://lore.kernel.org/all/CAKwvOdm_prtk1UQNJQGidZm44Lk582S3p=of0y46+rVjnSgXJg@mail.gmail.com

Ah, this is unfortunate.

-- 
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Andy Shevchenko



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Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Geert Uytterhoeven]

Hi Andy,

On Thu, 6 Nov 2025 at 17:09, Andy Shevchenko
<andriy.shevchenko@intel.com> wrote:
> On Thu, Nov 06, 2025 at 03:49:03PM +0100, Geert Uytterhoeven wrote:
> > On Thu, 6 Nov 2025 at 15:44, Andy Shevchenko
> > <andriy.shevchenko@intel.com> wrote:
> > > On Thu, Nov 06, 2025 at 02:34:00PM +0100, Geert Uytterhoeven wrote:
> > > > The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned
> > > > (long) long" _mask types.  For constant masks, that condition is usually
> > > > met, as GENMASK() yields an UL value.  The few places where the
> > > > constant mask is stored in an intermediate variable were fixed by
> > > > changing the variable type to u64 (see e.g. [1] and [2]).
> > > >
> > > > However, for non-constant masks, smaller unsigned types should be valid,
> > > > too, but currently lead to "result of comparison of constant
> > > > 18446744073709551615 with expression of type ... is always
> > > > false"-warnings with clang and W=1.
> > > >
> > > > Hence refactor the __BF_FIELD_CHECK() helper, and factor out
> > > > __FIELD_{GET,PREP}().  The later lack the single problematic check, but
> > > > are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
> > > > used in the fully non-const variants later.

> > > > +     BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) >               \
> > > > +                      __bf_cast_unsigned(reg, ~0ull),                \
> > > > +                      pfx "type of reg too small for mask")
> > >
> > > Perhaps we may convert this (and others?) to static_assert():s at some point?
> >
> > Nick tried that before, without success:
> > https://lore.kernel.org/all/CAKwvOdm_prtk1UQNJQGidZm44Lk582S3p=of0y46+rVjnSgXJg@mail.gmail.com
>
> Ah, this is unfortunate.

Of course, it might be an actual bug in the i915 driver...

The extra checking in field_prep() in case the compiler can
determine that the mask is a constant already found a possible bug
in drivers/net/wireless/realtek/rtw89/core.c:rtw89_roc_end():

    rtw89_write32_mask(rtwdev, reg, B_AX_RX_FLTR_CFG_MASK, rtwdev->hal.rx_fltr);

drivers/net/wireless/realtek/rtw89/reg.h:

    #define B_AX_RX_MPDU_MAX_LEN_MASK GENMASK(21, 16)
    #define B_AX_RX_FLTR_CFG_MASK ((u32)~B_AX_RX_MPDU_MAX_LEN_MASK)

so it looks like B_AX_RX_FLTR_CFG_MASK is not the proper mask for
this operation...

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

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Re: [PATCH v6 13/26] bitfield: Add non-constant field_{prep,get}() helpers

[Yury Norov]

On Thu, Nov 06, 2025 at 02:34:01PM +0100, Geert Uytterhoeven wrote:
> The existing FIELD_{GET,PREP}() macros are limited to compile-time
> constants.  However, it is very common to prepare or extract bitfield
> elements where the bitfield mask is not a compile-time constant.
> 
> To avoid this limitation, the AT91 clock driver and several other
> drivers already have their own non-const field_{prep,get}() macros.
> Make them available for general use by adding them to
> <linux/bitfield.h>, and improve them slightly:
>   1. Avoid evaluating macro parameters more than once,
>   2. Replace "ffs() - 1" by "__ffs()",
>   3. Support 64-bit use on 32-bit architectures,
>   4. Wire field_{get,prep}() to FIELD_{GET,PREP}() when mask is
>      actually constant.
> 
> This is deliberately not merged into the existing FIELD_{GET,PREP}()
> macros, as people expressed the desire to keep stricter variants for
> increased safety, or for performance critical paths.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Acked-by: Crt Mori <cmo@melexis.com>
> Acked-by: Nuno Sá <nuno.sa@analog.com>
> Acked-by: Richard Genoud <richard.genoud@bootlin.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
> ---
> v6:
>   - Align \,
>   - Add Return sections to kerneldoc,
>   - Add Reviewed-by,
>   - Document field_{get,prep} in top comment block,
>   - Use less-checking __FIELD_{GET,PREP}() to avoid build issues with
>     clang and W=1:
>     https://lore.kernel.org/all/202510281335.UpSLYJG9-lkp@intel.com
>     https://lore.kernel.org/all/202510281414.DnejZh4n-lkp@intel.com
>     https://lore.kernel.org/all/202510281304.RK3J3c3t-lkp@intel.com
> 
> v5:
>   - Add Acked-by,
>   - Split off changes outside <linux/bitfield.h>,
>   - Document that mask must be non-zero,
>   - Document typical usage pattern,
>   - Recommend using FIELD_{PREP,GET}() directly to ensure compile-time
>     constant masks,
>   - Check BITS_PER_TYPE(mask) instead of sizeof(mask),
>   - Wire field_{get,prep}() to FIELD_{GET,PREP}() when mask is
>     constant, to improve type checking.
> 
> v4:
>   - Add Acked-by,
>   - Rebase on top of commit 7c68005a46108ffa ("crypto: qat - relocate
>     power management debugfs helper APIs") in v6.17-rc1,
>   - Convert more recently introduced upstream copies:
>       - drivers/edac/ie31200_edac.c
>       - drivers/iio/dac/ad3530r.c
> 
> v3:
>   - Add Acked-by,
>   - Drop underscores from macro parameters,
>   - Use __auto_type where possible,
>   - Correctly cast reg to the mask type,
>   - Introduces __val and __reg intermediates to simplify the actual
>     operation,
>   - Drop unneeded parentheses,
>   - Clarify having both FIELD_{GET,PREP}() and field_{get,prep}(),
> 
> v2:
>   - Cast val resp. reg to the mask type,
>   - Fix 64-bit use on 32-bit architectures,
>   - Convert new upstream users:
>       - drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c
>       - drivers/gpio/gpio-aspeed.c
>       - drivers/iio/temperature/mlx90614.c
>       - drivers/pinctrl/nuvoton/pinctrl-ma35.c
>       - sound/usb/mixer_quirks.c
>   - Convert new user queued in renesas-devel for v6.15:
>       - drivers/soc/renesas/rz-sysc.c
> ---
>  include/linux/bitfield.h | 59 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
> 
> diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
> index bf8e0ae4b5b41038..f92e18c9629a59c6 100644
> --- a/include/linux/bitfield.h
> +++ b/include/linux/bitfield.h
> @@ -17,6 +17,7 @@
>   * FIELD_{GET,PREP} macros take as first parameter shifted mask
>   * from which they extract the base mask and shift amount.
>   * Mask must be a compilation time constant.
> + * field_{get,prep} are variants that take a non-const mask.
>   *
>   * Example:
>   *
> @@ -240,4 +241,62 @@ __MAKE_OP(64)
>  #undef __MAKE_OP
>  #undef ____MAKE_OP
>  
> +#define __field_prep(mask, val)						\
> +	({								\
> +		__auto_type __mask = (mask);				\
> +		typeof(mask) __val = (val);				\

typeof(__mask), I guess.

> +		unsigned int __shift = BITS_PER_TYPE(mask) <= 32 ?	\

Same here: BITS_PER_TYPE(__mask). BITS_PER_TYPE() doesn't evaluate the
expression because it is based on sizeof(). But we definitely don't
want people check it every time they read the code.

No need to send another version for this. I can fix it inplace.

Reviewed-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>

> +				       __ffs(__mask) : __ffs64(__mask);	\
> +		(__val << __shift) & __mask;				\
> +	})
> +
> +#define __field_get(mask, reg)						\
> +	({								\
> +		__auto_type __mask = (mask);				\
> +		typeof(mask) __reg =  (reg);				\
> +		unsigned int __shift = BITS_PER_TYPE(mask) <= 32 ?	\
> +				       __ffs(__mask) : __ffs64(__mask);	\
> +		(__reg & __mask) >> __shift;				\
> +	})
> +
> +/**
> + * field_prep() - prepare a bitfield element
> + * @mask: shifted mask defining the field's length and position, must be
> + *        non-zero
> + * @val:  value to put in the field
> + *
> + * Return: field value masked and shifted to its final destination
> + *
> + * field_prep() masks and shifts up the value.  The result should be
> + * combined with other fields of the bitfield using logical OR.
> + * Unlike FIELD_PREP(), @mask is not limited to a compile-time constant.
> + * Typical usage patterns are a value stored in a table, or calculated by
> + * shifting a constant by a variable number of bits.
> + * If you want to ensure that @mask is a compile-time constant, please use
> + * FIELD_PREP() directly instead.
> + */
> +#define field_prep(mask, val)						\
> +	(__builtin_constant_p(mask) ? __FIELD_PREP(mask, val, "field_prep: ") \
> +				    : __field_prep(mask, val))
> +
> +/**
> + * field_get() - extract a bitfield element
> + * @mask: shifted mask defining the field's length and position, must be
> + *        non-zero
> + * @reg:  value of entire bitfield
> + *
> + * Return: extracted field value
> + *
> + * field_get() extracts the field specified by @mask from the
> + * bitfield passed in as @reg by masking and shifting it down.
> + * Unlike FIELD_GET(), @mask is not limited to a compile-time constant.
> + * Typical usage patterns are a value stored in a table, or calculated by
> + * shifting a constant by a variable number of bits.
> + * If you want to ensure that @mask is a compile-time constant, please use
> + * FIELD_GET() directly instead.
> + */
> +#define field_get(mask, reg)						\
> +	(__builtin_constant_p(mask) ? __FIELD_GET(mask, reg, "field_get: ") \
> +				    : __field_get(mask, reg))
> +
>  #endif
> -- 
> 2.43.0

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Re: [PATCH v6 00/26] Non-const bitfield helpers

[Yury Norov]

On Thu, Nov 06, 2025 at 02:33:48PM +0100, Geert Uytterhoeven wrote:
> 	Hi all,
> 
> <linux/bitfield.h> contains various helpers for accessing bitfields, as
> typically used in hardware registers for memory-mapped I/O blocks.
> These helpers ensure type safety, and deduce automatically shift values
> from mask values, avoiding mistakes due to inconsistent shifts and
> masks, and leading to a reduction in source code size.
> 
> The existing FIELD_{GET,PREP}() macros are limited to compile-time
> constants.  However, it is very common to prepare or extract bitfield
> elements where the bitfield mask is not a compile-time constant (e.g. it
> comes from a table, or is created by shifting a compile-time constant).
> To avoid this limitation, the AT91 clock driver introduced its own
> field_{prep,get}() macros.  During the past four years, these have been
> copied to multiple drivers, and more copies are on their way[1], leading
> to the obvious review comment "please move this to <linux/bitfield.h>".
> 
> Hence this series
>   1. Takes preparatory steps in drivers definining local
>      field_{get,prep}() macros (patches 1-11),
>   2. Introduces __FIELD_{PREP,GET}() helpers to avoid clang W=1 warnings
>      (patch 12),
>   3. Makes field_{prep,get}() available for general use (patch 13),
>   4. Converts drivers with local variants to the common helpers (patches
>      14-24),
>   5. Converts a few Renesas drivers to the existing FIELD_{GET,PREP}()
>      and the new field_{get,prep}() helpers (patches 25-26).
> 
> Alternatives would be to use the typed {u*,be*,le*,...}_{get,encode}_bits()
> macros instead (which currently do not work with non-constant masks
> either, and the first attempt to change that generates much worse code),
> or to store the low bit and width of the mask instead (which would
> require changing all code that passes masks directly, and also generates
> worse code).

Everyone please send your tags. I'm going to merge it in
bitmap-for-next before Monday.

Thanks,
Yury

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Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Andy Shevchenko]

On Fri, Nov 7, 2025 at 3:16 AM Ping-Ke Shih <pkshih@realtek.com> wrote:
>
> Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Thu, 6 Nov 2025 at 17:09, Andy Shevchenko
> > <andriy.shevchenko@intel.com> wrote:
> > > On Thu, Nov 06, 2025 at 03:49:03PM +0100, Geert Uytterhoeven wrote:
> > > > On Thu, 6 Nov 2025 at 15:44, Andy Shevchenko
> > > > <andriy.shevchenko@intel.com> wrote:
> > > > > On Thu, Nov 06, 2025 at 02:34:00PM +0100, Geert Uytterhoeven wrote:
> > > > > > The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned
> > > > > > (long) long" _mask types.  For constant masks, that condition is usually
> > > > > > met, as GENMASK() yields an UL value.  The few places where the
> > > > > > constant mask is stored in an intermediate variable were fixed by
> > > > > > changing the variable type to u64 (see e.g. [1] and [2]).
> > > > > >
> > > > > > However, for non-constant masks, smaller unsigned types should be valid,
> > > > > > too, but currently lead to "result of comparison of constant
> > > > > > 18446744073709551615 with expression of type ... is always
> > > > > > false"-warnings with clang and W=1.
> > > > > >
> > > > > > Hence refactor the __BF_FIELD_CHECK() helper, and factor out
> > > > > > __FIELD_{GET,PREP}().  The later lack the single problematic check, but
> > > > > > are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
> > > > > > used in the fully non-const variants later.
> >
> > > > > > +     BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) >               \
> > > > > > +                      __bf_cast_unsigned(reg, ~0ull),                \
> > > > > > +                      pfx "type of reg too small for mask")
> > > > >
> > > > > Perhaps we may convert this (and others?) to static_assert():s at some point?
> > > >
> > > > Nick tried that before, without success:
> > > > https://lore.kernel.org/all/CAKwvOdm_prtk1UQNJQGidZm44Lk582S3p=of0y46+rVjnSgXJg@mail.gmail.com
> > >
> > > Ah, this is unfortunate.
> >
> > Of course, it might be an actual bug in the i915 driver...
> >
> > The extra checking in field_prep() in case the compiler can
> > determine that the mask is a constant already found a possible bug
> > in drivers/net/wireless/realtek/rtw89/core.c:rtw89_roc_end():
> >
> >     rtw89_write32_mask(rtwdev, reg, B_AX_RX_FLTR_CFG_MASK, rtwdev->hal.rx_fltr);
> >
> > drivers/net/wireless/realtek/rtw89/reg.h:
> >
> >     #define B_AX_RX_MPDU_MAX_LEN_MASK GENMASK(21, 16)
> >     #define B_AX_RX_FLTR_CFG_MASK ((u32)~B_AX_RX_MPDU_MAX_LEN_MASK)
> >
> > so it looks like B_AX_RX_FLTR_CFG_MASK is not the proper mask for
> > this operation...
>
> The purpose of the statements is to update values excluding bits of
> B_AX_RX_MPDU_MAX_LEN_MASK. The use of B_AX_RX_FLTR_CFG_MASK is tricky, but
> the operation is correct because bit 0 is set, so __ffs(mask) returns 0 in
> rtw89_write32_mask(). Then, operation looks like
>
>    orig = read(reg);
>    new = (orig & ~mask) | (data & mask);
>    write(new);
>
> Since we don't use FIELD_{GET,PREP} macros with B_AX_RX_FLTR_CFG_MASK, how
> can you find the problem? Please guide us. Thanks.

Isn't FIELD_MODIFY() what you want to use?

-- 
With Best Regards,
Andy Shevchenko

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Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Geert Uytterhoeven]

Hi Ping-Ke,

On Fri, 7 Nov 2025 at 02:16, Ping-Ke Shih <pkshih@realtek.com> wrote:
> Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > The extra checking in field_prep() in case the compiler can
> > determine that the mask is a constant already found a possible bug
> > in drivers/net/wireless/realtek/rtw89/core.c:rtw89_roc_end():
> >
> >     rtw89_write32_mask(rtwdev, reg, B_AX_RX_FLTR_CFG_MASK, rtwdev->hal.rx_fltr);
> >
> > drivers/net/wireless/realtek/rtw89/reg.h:
> >
> >     #define B_AX_RX_MPDU_MAX_LEN_MASK GENMASK(21, 16)
> >     #define B_AX_RX_FLTR_CFG_MASK ((u32)~B_AX_RX_MPDU_MAX_LEN_MASK)
> >
> > so it looks like B_AX_RX_FLTR_CFG_MASK is not the proper mask for
> > this operation...
>
> The purpose of the statements is to update values excluding bits of
> B_AX_RX_MPDU_MAX_LEN_MASK. The use of B_AX_RX_FLTR_CFG_MASK is tricky, but
> the operation is correct because bit 0 is set, so __ffs(mask) returns 0 in
> rtw89_write32_mask(). Then, operation looks like
>
>    orig = read(reg);
>    new = (orig & ~mask) | (data & mask);
>    write(new);

Thanks for your quick confirmation!
So the intention really is to clear bits 22-31, and write the rx_fltr
value to bits 0-15?

if the clearing is not needed, it would be better to use
#define B_AX_RX_FLTR_CFG_MASK GENMASK(15, 0)

If the clearing is needed, I still think it would be better to
change B_AX_RX_FLTR_CFG_MASK, and split the clearing off in a separate
operation, to make it more explicit and obvious for the casual reader.

> Since we don't use FIELD_{GET,PREP} macros with B_AX_RX_FLTR_CFG_MASK, how
> can you find the problem? Please guide us. Thanks.

I still have "[PATCH/RFC 17/17] rtw89: Use bitfield helpers"
https://lore.kernel.org/all/f7b81122f7596fa004188bfae68f25a68c2d2392.1637592133.git.geert+renesas@glider.be/
in my local tree, which started flagging the use of a discontiguous
mask with the improved checking in field_prep().

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

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Re: [PATCH -next v6 10/26] iio: imu: smi330: #undef field_{get,prep}() before definition

[Jonathan Cameron]

On Thu,  6 Nov 2025 14:33:58 +0100
Geert Uytterhoeven <geert+renesas@glider.be> wrote:

> Prepare for the advent of globally available common field_get() and
> field_prep() macros by undefining the symbols before defining local
> variants.  This prevents redefinition warnings from the C preprocessor
> when introducing the common macros later.
> 
> Suggested-by: Yury Norov <yury.norov@gmail.com>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
I tweaked the original driver to avoid the naming clash so this can be dropped
and we can replace with the new function next cycle.

Thanks,

Jonathan

> ---
> v6:
>   - No changes,
> 
> v5:
>   - New.
> ---
>  drivers/iio/imu/smi330/smi330_core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iio/imu/smi330/smi330_core.c b/drivers/iio/imu/smi330/smi330_core.c
> index d9178725ade3da83..a79964fe68fadf47 100644
> --- a/drivers/iio/imu/smi330/smi330_core.c
> +++ b/drivers/iio/imu/smi330/smi330_core.c
> @@ -68,7 +68,9 @@
>  #define SMI330_SOFT_RESET_DELAY 2000
>  
>  /* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
> +#undef field_get
>  #define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
> +#undef field_prep
>  #define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
>  
>  #define SMI330_ACCEL_CHANNEL(_axis) {					\


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Re: [PATCH v6 05/26] iio: dac: ad3530r: #undef field_prep() before local definition

[Jonathan Cameron]

On Thu,  6 Nov 2025 14:33:53 +0100
Geert Uytterhoeven <geert+renesas@glider.be> wrote:

> Prepare for the advent of a globally available common field_prep() macro
> by undefining the symbol before defining a local variant.  This prevents
> redefinition warnings from the C preprocessor when introducing the common
> macro later.
> 
> Suggested-by: Yury Norov <yury.norov@gmail.com>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Jonathan Cameron <jonathan.cameron@huawei.com>


> ---
> v6:
>   - No changes,
> 
> v5:
>   - New.
> ---
>  drivers/iio/dac/ad3530r.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/iio/dac/ad3530r.c b/drivers/iio/dac/ad3530r.c
> index 6134613777b8e1d4..5684d11137f29948 100644
> --- a/drivers/iio/dac/ad3530r.c
> +++ b/drivers/iio/dac/ad3530r.c
> @@ -54,6 +54,7 @@
>  #define AD3531R_MAX_CHANNELS			4
>  
>  /* Non-constant mask variant of FIELD_PREP() */
> +#undef field_prep
>  #define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))
>  
>  enum ad3530r_mode {


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Re: [PATCH v6 06/26] iio: mlx90614: #undef field_{get,prep}() before local definition

[Jonathan Cameron]

On Thu,  6 Nov 2025 14:33:54 +0100
Geert Uytterhoeven <geert+renesas@glider.be> wrote:

> Prepare for the advent of globally available common field_get() and
> field_prep() macros by undefining the symbols before defining local
> variants.  This prevents redefinition warnings from the C preprocessor
> when introducing the common macros later.
> 
> Suggested-by: Yury Norov <yury.norov@gmail.com>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Jonathan Cameron <jonathan.cameron@huawei.com>

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Re: [PATCH -next v6 23/26] iio: imu: smi330: Convert to common field_{get,prep}() helpers

[Jonathan Cameron]

On Thu,  6 Nov 2025 14:34:11 +0100
Geert Uytterhoeven <geert+renesas@glider.be> wrote:

> Drop the driver-specific field_get() and field_prep() macros, in favor
> of the globally available variants from <linux/bitfield.h>.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

This will need a revist next cycle. I preferred not to have
the odd looking undef in the driver at introduction so prefixed with smi330_
instead.  Only one instance so it wasn't worth comments to make ti clear what was going on.

J


> ---
> v6:
>   - No changes,
> 
> v5:
>   - New.
> ---
>  drivers/iio/imu/smi330/smi330_core.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/iio/imu/smi330/smi330_core.c b/drivers/iio/imu/smi330/smi330_core.c
> index a79964fe68fadf47..83e0dff5d973d046 100644
> --- a/drivers/iio/imu/smi330/smi330_core.c
> +++ b/drivers/iio/imu/smi330/smi330_core.c
> @@ -67,12 +67,6 @@
>  #define SMI330_CHIP_ID 0x42
>  #define SMI330_SOFT_RESET_DELAY 2000
>  
> -/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
> -#undef field_get
> -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
> -#undef field_prep
> -#define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
> -
>  #define SMI330_ACCEL_CHANNEL(_axis) {					\
>  	.type = IIO_ACCEL,						\
>  	.modified = 1,							\


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Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Geert Uytterhoeven]

Hi Ady,

On Fri, 7 Nov 2025 at 09:00, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> On Fri, Nov 7, 2025 at 3:16 AM Ping-Ke Shih <pkshih@realtek.com> wrote:
> > Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > On Thu, 6 Nov 2025 at 17:09, Andy Shevchenko
> > > <andriy.shevchenko@intel.com> wrote:
> > > > On Thu, Nov 06, 2025 at 03:49:03PM +0100, Geert Uytterhoeven wrote:
> > > > > On Thu, 6 Nov 2025 at 15:44, Andy Shevchenko
> > > > > <andriy.shevchenko@intel.com> wrote:
> > > > > > On Thu, Nov 06, 2025 at 02:34:00PM +0100, Geert Uytterhoeven wrote:
> > > > > > > The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned
> > > > > > > (long) long" _mask types.  For constant masks, that condition is usually
> > > > > > > met, as GENMASK() yields an UL value.  The few places where the
> > > > > > > constant mask is stored in an intermediate variable were fixed by
> > > > > > > changing the variable type to u64 (see e.g. [1] and [2]).
> > > > > > >
> > > > > > > However, for non-constant masks, smaller unsigned types should be valid,
> > > > > > > too, but currently lead to "result of comparison of constant
> > > > > > > 18446744073709551615 with expression of type ... is always
> > > > > > > false"-warnings with clang and W=1.
> > > > > > >
> > > > > > > Hence refactor the __BF_FIELD_CHECK() helper, and factor out
> > > > > > > __FIELD_{GET,PREP}().  The later lack the single problematic check, but
> > > > > > > are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
> > > > > > > used in the fully non-const variants later.
> > >
> > > > > > > +     BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) >               \
> > > > > > > +                      __bf_cast_unsigned(reg, ~0ull),                \
> > > > > > > +                      pfx "type of reg too small for mask")
> > > > > >
> > > > > > Perhaps we may convert this (and others?) to static_assert():s at some point?
> > > > >
> > > > > Nick tried that before, without success:
> > > > > https://lore.kernel.org/all/CAKwvOdm_prtk1UQNJQGidZm44Lk582S3p=of0y46+rVjnSgXJg@mail.gmail.com
> > > >
> > > > Ah, this is unfortunate.
> > >
> > > Of course, it might be an actual bug in the i915 driver...
> > >
> > > The extra checking in field_prep() in case the compiler can
> > > determine that the mask is a constant already found a possible bug
> > > in drivers/net/wireless/realtek/rtw89/core.c:rtw89_roc_end():
> > >
> > >     rtw89_write32_mask(rtwdev, reg, B_AX_RX_FLTR_CFG_MASK, rtwdev->hal.rx_fltr);
> > >
> > > drivers/net/wireless/realtek/rtw89/reg.h:
> > >
> > >     #define B_AX_RX_MPDU_MAX_LEN_MASK GENMASK(21, 16)
> > >     #define B_AX_RX_FLTR_CFG_MASK ((u32)~B_AX_RX_MPDU_MAX_LEN_MASK)
> > >
> > > so it looks like B_AX_RX_FLTR_CFG_MASK is not the proper mask for
> > > this operation...
> >
> > The purpose of the statements is to update values excluding bits of
> > B_AX_RX_MPDU_MAX_LEN_MASK. The use of B_AX_RX_FLTR_CFG_MASK is tricky, but
> > the operation is correct because bit 0 is set, so __ffs(mask) returns 0 in
> > rtw89_write32_mask(). Then, operation looks like
> >
> >    orig = read(reg);
> >    new = (orig & ~mask) | (data & mask);
> >    write(new);
> >
> > Since we don't use FIELD_{GET,PREP} macros with B_AX_RX_FLTR_CFG_MASK, how
> > can you find the problem? Please guide us. Thanks.
>
> Isn't FIELD_MODIFY() what you want to use?

FIELD_MODIFY() is a rather recent addition.
That is also the reason why I didn't add a non-const field_modify() yet
(I didn't want to risk delaying this series even more ;-)

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

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RE: [PATCH v6 03/26] EDAC/ie31200: #undef field_get() before local definition

[Zhuo, Qiuxu]

> From: Geert Uytterhoeven <geert+renesas@glider.be>
> Sent: Thursday, November 6, 2025 9:34 PM
> To: Yury Norov <yury.norov@gmail.com>; Michael Turquette
> <mturquette@baylibre.com>; Stephen Boyd <sboyd@kernel.org>; Nicolas
> Ferre <nicolas.ferre@microchip.com>; Alexandre Belloni
> <alexandre.belloni@bootlin.com>; Claudiu Beznea
> <claudiu.beznea@tuxon.dev>; Cabiddu, Giovanni
> <giovanni.cabiddu@intel.com>; Herbert Xu <herbert@gondor.apana.org.au>;
> David Miller <davem@davemloft.net>; Linus Walleij
> <linus.walleij@linaro.org>; Bartosz Golaszewski <brgl@bgdev.pl>; Joel Stanley
> <joel@jms.id.au>; Andrew Jeffery <andrew@codeconstruct.com.au>; Crt
> Mori <cmo@melexis.com>; Jonathan Cameron <jic23@kernel.org>; Lars-
> Peter Clausen <lars@metafoo.de>; Jacky Huang <ychuang3@nuvoton.com>;
> Shan-Chun Hung <schung@nuvoton.com>; Rasmus Villemoes
> <linux@rasmusvillemoes.dk>; Jaroslav Kysela <perex@perex.cz>; Takashi Iwai
> <tiwai@suse.com>; Johannes Berg <johannes@sipsolutions.net>; Jakub
> Kicinski <kuba@kernel.org>; Alex Elder <elder@ieee.org>; David Laight
> <david.laight.linux@gmail.com>; Vincent Mailhol
> <mailhol.vincent@wanadoo.fr>; Jason Baron <jbaron@akamai.com>; Borislav
> Petkov <bp@alien8.de>; Luck, Tony <tony.luck@intel.com>; Michael
> Hennerich <Michael.Hennerich@analog.com>; Kim Seer Paller
> <kimseer.paller@analog.com>; Lechner, David <dlechner@baylibre.com>;
> Nuno Sá <nuno.sa@analog.com>; Andy Shevchenko <andy@kernel.org>;
> Richard Genoud <richard.genoud@bootlin.com>; Cosmin Tanislav
> <demonsingur@gmail.com>; Biju Das <biju.das.jz@bp.renesas.com>;
> Jianping Shen <Jianping.Shen@de.bosch.com>; Nathan Chancellor
> <nathan@kernel.org>; Nick Desaulniers <nick.desaulniers+lkml@gmail.com>;
> Miquel Raynal <miquel.raynal@bootlin.com>; Richard Weinberger
> <richard@nod.at>; Vignesh Raghavendra <vigneshr@ti.com>
> Cc: linux-clk@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> renesas-soc@vger.kernel.org; linux-crypto@vger.kernel.org; linux-
> edac@vger.kernel.org; qat-linux <qat-linux@intel.com>; linux-
> gpio@vger.kernel.org; linux-aspeed@lists.ozlabs.org; linux-
> iio@vger.kernel.org; linux-sound@vger.kernel.org; linux-
> mtd@lists.infradead.org; linux-kernel@vger.kernel.org; Geert Uytterhoeven
> <geert+renesas@glider.be>
> Subject: [PATCH v6 03/26] EDAC/ie31200: #undef field_get() before local
> definition
> 
> Prepare for the advent of a globally available common field_get() macro by
> undefining the symbol before defining a local variant.  This prevents
> redefinition warnings from the C preprocessor when introducing the common
> macro later.
> 
> Suggested-by: Yury Norov <yury.norov@gmail.com>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Good to see the global field_{get,prep}() macros are available for use.
Thanks.

Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>

> [...]

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RE: [PATCH v6 16/26] EDAC/ie31200: Convert to common field_get() helper

[Zhuo, Qiuxu]

> From: Geert Uytterhoeven <geert+renesas@glider.be>
> Sent: Thursday, November 6, 2025 9:34 PM
> To: Yury Norov <yury.norov@gmail.com>; Michael Turquette
> <mturquette@baylibre.com>; Stephen Boyd <sboyd@kernel.org>; Nicolas
> Ferre <nicolas.ferre@microchip.com>; Alexandre Belloni
> <alexandre.belloni@bootlin.com>; Claudiu Beznea
> <claudiu.beznea@tuxon.dev>; Cabiddu, Giovanni
> <giovanni.cabiddu@intel.com>; Herbert Xu <herbert@gondor.apana.org.au>;
> David Miller <davem@davemloft.net>; Linus Walleij
> <linus.walleij@linaro.org>; Bartosz Golaszewski <brgl@bgdev.pl>; Joel Stanley
> <joel@jms.id.au>; Andrew Jeffery <andrew@codeconstruct.com.au>; Crt
> Mori <cmo@melexis.com>; Jonathan Cameron <jic23@kernel.org>; Lars-
> Peter Clausen <lars@metafoo.de>; Jacky Huang <ychuang3@nuvoton.com>;
> Shan-Chun Hung <schung@nuvoton.com>; Rasmus Villemoes
> <linux@rasmusvillemoes.dk>; Jaroslav Kysela <perex@perex.cz>; Takashi Iwai
> <tiwai@suse.com>; Johannes Berg <johannes@sipsolutions.net>; Jakub
> Kicinski <kuba@kernel.org>; Alex Elder <elder@ieee.org>; David Laight
> <david.laight.linux@gmail.com>; Vincent Mailhol
> <mailhol.vincent@wanadoo.fr>; Jason Baron <jbaron@akamai.com>; Borislav
> Petkov <bp@alien8.de>; Luck, Tony <tony.luck@intel.com>; Michael
> Hennerich <Michael.Hennerich@analog.com>; Kim Seer Paller
> <kimseer.paller@analog.com>; Lechner, David <dlechner@baylibre.com>;
> Nuno Sá <nuno.sa@analog.com>; Andy Shevchenko <andy@kernel.org>;
> Richard Genoud <richard.genoud@bootlin.com>; Cosmin Tanislav
> <demonsingur@gmail.com>; Biju Das <biju.das.jz@bp.renesas.com>;
> Jianping Shen <Jianping.Shen@de.bosch.com>; Nathan Chancellor
> <nathan@kernel.org>; Nick Desaulniers <nick.desaulniers+lkml@gmail.com>;
> Miquel Raynal <miquel.raynal@bootlin.com>; Richard Weinberger
> <richard@nod.at>; Vignesh Raghavendra <vigneshr@ti.com>
> Cc: linux-clk@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> renesas-soc@vger.kernel.org; linux-crypto@vger.kernel.org; linux-
> edac@vger.kernel.org; qat-linux <qat-linux@intel.com>; linux-
> gpio@vger.kernel.org; linux-aspeed@lists.ozlabs.org; linux-
> iio@vger.kernel.org; linux-sound@vger.kernel.org; linux-
> mtd@lists.infradead.org; linux-kernel@vger.kernel.org; Geert Uytterhoeven
> <geert+renesas@glider.be>
> Subject: [PATCH v6 16/26] EDAC/ie31200: Convert to common field_get()
> helper
> 
> Drop the driver-specific field_get() macro, in favor of the globally available
> variant from <linux/bitfield.h>.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Good to see the global field_{get,prep}() macros are available for use.
Thanks.

Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>

> [...]

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