| Message ID | 1824412519cb8791ab428065116927ee7b77cf35.1738329459.git.geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Non-const bitfield helpers | expand |
On 31/01/2025 14:46:51+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 consolidating them in > <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. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> > --- > 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 > --- > drivers/clk/at91/clk-peripheral.c | 1 + > drivers/clk/at91/pmc.h | 3 -- > .../qat/qat_common/adf_gen4_pm_debugfs.c | 8 +---- > drivers/gpio/gpio-aspeed.c | 5 +-- > drivers/iio/temperature/mlx90614.c | 5 +-- > drivers/pinctrl/nuvoton/pinctrl-ma35.c | 4 --- > drivers/soc/renesas/rz-sysc.c | 3 +- > include/linux/bitfield.h | 34 +++++++++++++++++++ > sound/usb/mixer_quirks.c | 4 --- > 9 files changed, 39 insertions(+), 28 deletions(-) > > diff --git a/drivers/clk/at91/clk-peripheral.c b/drivers/clk/at91/clk-peripheral.c > index c173a44c800aa8cc..60208bdc3fe4797e 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 4fb29ca111f7d427..3838e4f7df2d4a70 100644 > --- a/drivers/clk/at91/pmc.h > +++ b/drivers/clk/at91/pmc.h > @@ -116,9 +116,6 @@ struct at91_clk_pms { > unsigned int parent; > }; > > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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) > > diff --git a/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c b/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c > index 2e4095c4c12c94f9..ebaa59e934178309 100644 > --- a/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c > +++ b/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c > @@ -1,5 +1,6 @@ > // SPDX-License-Identifier: GPL-2.0-only > /* Copyright(c) 2023 Intel Corporation */ > +#include <linux/bitfield.h> > #include <linux/dma-mapping.h> > #include <linux/kernel.h> > #include <linux/string_helpers.h> > @@ -11,13 +12,6 @@ > #include "adf_gen4_pm.h" > #include "icp_qat_fw_init_admin.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. > - */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > - > #define PM_INFO_MEMBER_OFF(member) \ > (offsetof(struct icp_qat_fw_init_admin_pm_info, member) / sizeof(u32)) > > diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c > index 40c1bd80f8b0434d..b45e4dd8d8e4f00a 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/clk.h> > #include <linux/gpio/aspeed.h> > #include <linux/gpio/driver.h> > @@ -30,10 +31,6 @@ > #include <linux/gpio/consumer.h> > #include "gpiolib.h" > > -/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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 > diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c > index 740018d4b3dfb35e..c58dc59d4f570831 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> > @@ -68,10 +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() */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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 */ > diff --git a/drivers/pinctrl/nuvoton/pinctrl-ma35.c b/drivers/pinctrl/nuvoton/pinctrl-ma35.c > index 59c4e7c6cddea127..3ba28faa8e1418a9 100644 > --- a/drivers/pinctrl/nuvoton/pinctrl-ma35.c > +++ b/drivers/pinctrl/nuvoton/pinctrl-ma35.c > @@ -81,10 +81,6 @@ > #define MVOLT_1800 0 > #define MVOLT_3300 1 > > -/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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", > diff --git a/drivers/soc/renesas/rz-sysc.c b/drivers/soc/renesas/rz-sysc.c > index 1c98da37b7d18745..917a029d849585cd 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/io.h> > #include <linux/of.h> > #include <linux/platform_device.h> > @@ -12,8 +13,6 @@ > > #include "rz-sysc.h" > > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > - > /** > * struct rz_sysc - RZ SYSC private data structure > * @base: SYSC base address > diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h > index 63928f1732230700..c62324a9fcc81241 100644 > --- a/include/linux/bitfield.h > +++ b/include/linux/bitfield.h > @@ -203,4 +203,38 @@ __MAKE_OP(64) > #undef __MAKE_OP > #undef ____MAKE_OP > > +/** > + * field_prep() - prepare a bitfield element > + * @_mask: shifted mask defining the field's length and position > + * @_val: value to put in the field > + * > + * 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. > + */ > +#define field_prep(_mask, _val) \ > + ({ \ > + typeof(_mask) __mask = (_mask); \ > + unsigned int __shift = sizeof(_mask) <= 4 ? \ > + __ffs(__mask) : __ffs64(__mask); \ > + (((typeof(_mask))(_val) << __shift) & (__mask)); \ > + }) > + > +/** > + * field_get() - extract a bitfield element > + * @_mask: shifted mask defining the field's length and position > + * @_reg: value of entire bitfield > + * > + * 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. > + */ > +#define field_get(_mask, _reg) \ > + ({ \ > + typeof(_mask) __mask = _mask; \ > + unsigned int __shift = sizeof(_mask) <= 4 ? \ > + __ffs(__mask) : __ffs64(__mask); \ > + (typeof(_mask))(((_reg) & (__mask)) >> __shift); \ > + }) > + > #endif > diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c > index 23fcd680167d0298..00ab811e4b11a573 100644 > --- a/sound/usb/mixer_quirks.c > +++ b/sound/usb/mixer_quirks.c > @@ -3109,10 +3109,6 @@ 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 */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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); > -- > 2.43.0 >
On Fri, 31 Jan 2025 14:46:51 +0100 Geert Uytterhoeven <geert+renesas@glider.be> 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 consolidating them in > <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. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> For the IIO one. Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > 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 > --- > drivers/clk/at91/clk-peripheral.c | 1 + > drivers/clk/at91/pmc.h | 3 -- > .../qat/qat_common/adf_gen4_pm_debugfs.c | 8 +---- > drivers/gpio/gpio-aspeed.c | 5 +-- > drivers/iio/temperature/mlx90614.c | 5 +-- > drivers/pinctrl/nuvoton/pinctrl-ma35.c | 4 --- > drivers/soc/renesas/rz-sysc.c | 3 +- > include/linux/bitfield.h | 34 +++++++++++++++++++ > sound/usb/mixer_quirks.c | 4 --- > 9 files changed, 39 insertions(+), 28 deletions(-) > > diff --git a/drivers/clk/at91/clk-peripheral.c b/drivers/clk/at91/clk-peripheral.c > index c173a44c800aa8cc..60208bdc3fe4797e 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 4fb29ca111f7d427..3838e4f7df2d4a70 100644 > --- a/drivers/clk/at91/pmc.h > +++ b/drivers/clk/at91/pmc.h > @@ -116,9 +116,6 @@ struct at91_clk_pms { > unsigned int parent; > }; > > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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) > > diff --git a/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c b/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c > index 2e4095c4c12c94f9..ebaa59e934178309 100644 > --- a/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c > +++ b/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c > @@ -1,5 +1,6 @@ > // SPDX-License-Identifier: GPL-2.0-only > /* Copyright(c) 2023 Intel Corporation */ > +#include <linux/bitfield.h> > #include <linux/dma-mapping.h> > #include <linux/kernel.h> > #include <linux/string_helpers.h> > @@ -11,13 +12,6 @@ > #include "adf_gen4_pm.h" > #include "icp_qat_fw_init_admin.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. > - */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > - > #define PM_INFO_MEMBER_OFF(member) \ > (offsetof(struct icp_qat_fw_init_admin_pm_info, member) / sizeof(u32)) > > diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c > index 40c1bd80f8b0434d..b45e4dd8d8e4f00a 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/clk.h> > #include <linux/gpio/aspeed.h> > #include <linux/gpio/driver.h> > @@ -30,10 +31,6 @@ > #include <linux/gpio/consumer.h> > #include "gpiolib.h" > > -/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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 > diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c > index 740018d4b3dfb35e..c58dc59d4f570831 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> > @@ -68,10 +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() */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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 */ > diff --git a/drivers/pinctrl/nuvoton/pinctrl-ma35.c b/drivers/pinctrl/nuvoton/pinctrl-ma35.c > index 59c4e7c6cddea127..3ba28faa8e1418a9 100644 > --- a/drivers/pinctrl/nuvoton/pinctrl-ma35.c > +++ b/drivers/pinctrl/nuvoton/pinctrl-ma35.c > @@ -81,10 +81,6 @@ > #define MVOLT_1800 0 > #define MVOLT_3300 1 > > -/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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", > diff --git a/drivers/soc/renesas/rz-sysc.c b/drivers/soc/renesas/rz-sysc.c > index 1c98da37b7d18745..917a029d849585cd 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/io.h> > #include <linux/of.h> > #include <linux/platform_device.h> > @@ -12,8 +13,6 @@ > > #include "rz-sysc.h" > > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > - > /** > * struct rz_sysc - RZ SYSC private data structure > * @base: SYSC base address > diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h > index 63928f1732230700..c62324a9fcc81241 100644 > --- a/include/linux/bitfield.h > +++ b/include/linux/bitfield.h > @@ -203,4 +203,38 @@ __MAKE_OP(64) > #undef __MAKE_OP > #undef ____MAKE_OP > > +/** > + * field_prep() - prepare a bitfield element > + * @_mask: shifted mask defining the field's length and position > + * @_val: value to put in the field > + * > + * 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. > + */ > +#define field_prep(_mask, _val) \ > + ({ \ > + typeof(_mask) __mask = (_mask); \ > + unsigned int __shift = sizeof(_mask) <= 4 ? \ > + __ffs(__mask) : __ffs64(__mask); \ > + (((typeof(_mask))(_val) << __shift) & (__mask)); \ > + }) > + > +/** > + * field_get() - extract a bitfield element > + * @_mask: shifted mask defining the field's length and position > + * @_reg: value of entire bitfield > + * > + * 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. > + */ > +#define field_get(_mask, _reg) \ > + ({ \ > + typeof(_mask) __mask = _mask; \ > + unsigned int __shift = sizeof(_mask) <= 4 ? \ > + __ffs(__mask) : __ffs64(__mask); \ > + (typeof(_mask))(((_reg) & (__mask)) >> __shift); \ > + }) > + > #endif > diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c > index 23fcd680167d0298..00ab811e4b11a573 100644 > --- a/sound/usb/mixer_quirks.c > +++ b/sound/usb/mixer_quirks.c > @@ -3109,10 +3109,6 @@ 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 */ > -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) > -#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);
On Fri, 31 Jan 2025 14:46:51 +0100 Geert Uytterhoeven <geert+renesas@glider.be> 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 consolidating them in > <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. ... > diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h > index 63928f1732230700..c62324a9fcc81241 100644 > --- a/include/linux/bitfield.h > +++ b/include/linux/bitfield.h > @@ -203,4 +203,38 @@ __MAKE_OP(64) > #undef __MAKE_OP > #undef ____MAKE_OP > > +/** > + * field_prep() - prepare a bitfield element > + * @_mask: shifted mask defining the field's length and position > + * @_val: value to put in the field > + * > + * 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. > + */ > +#define field_prep(_mask, _val) \ You don't need an _ prefix on the 'parameters' - it doesn't gain anything. > + ({ \ > + typeof(_mask) __mask = (_mask); \ Use: __auto_type __mask = (_mask); > + unsigned int __shift = sizeof(_mask) <= 4 ? \ > + __ffs(__mask) : __ffs64(__mask); \ > + (((typeof(_mask))(_val) << __shift) & (__mask)); \ There are a lot of () in that line, perhaps: __auto_type(__mask) = (_mask); typeof (__mask) __val = (_val); unsigned int __shift = ...; (__val << __shift) & __mask; Note the typeof (__mask) - avoids line-length 'bloat' when the arguments are non-trivial. David
On 31/01/2025 at 22:46, 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. Why is it that the existing FIELD_{GET,PREP}() macros must be limited to compile time constants? Instead of creating another variant for non-constant bitfields, wouldn't it be better to make the existing macro accept both? As far as I can see, only __BUILD_BUG_ON_NOT_POWER_OF_2() and __BF_FIELD_CHECK() need to be adjusted. I am thinking of this: diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h index 63928f173223..c6bedab862d1 100644 --- a/include/linux/bitfield.h +++ b/include/linux/bitfield.h @@ -8,6 +8,7 @@ #define _LINUX_BITFIELD_H #include <linux/build_bug.h> +#include <linux/compiler.h> #include <asm/byteorder.h> /* @@ -62,15 +63,13 @@ #define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \ ({ \ - BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \ - _pfx "mask is not constant"); \ - BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero"); \ - BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \ - ~((_mask) >> __bf_shf(_mask)) & \ - (0 + (_val)) : 0, \ + BUILD_BUG_ON_MSG(statically_true((_mask) == 0), \ + _pfx "mask is zero"); \ + BUILD_BUG_ON_MSG(statically_true(~((_mask) >> __bf_shf(_mask)) & \ + (0 + (_val))), \ _pfx "value too large for the field"); \ - BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \ - __bf_cast_unsigned(_reg, ~0ull), \ + BUILD_BUG_ON_MSG(statically_true(__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))); \ diff --git a/include/linux/build_bug.h b/include/linux/build_bug.h index 3aa3640f8c18..3b8055ebb55f 100644 --- a/include/linux/build_bug.h +++ b/include/linux/build_bug.h @@ -18,9 +18,9 @@ /* Force a compilation error if a constant expression is not a power of 2 */ #define __BUILD_BUG_ON_NOT_POWER_OF_2(n) \ - BUILD_BUG_ON(((n) & ((n) - 1)) != 0) + BUILD_BUG_ON(statically_true((n) & ((n) - 1))) #define BUILD_BUG_ON_NOT_POWER_OF_2(n) \ - BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0)) + BUILD_BUG_ON(statically_true(!(n) || ((n) & ((n) - 1)))) /* * BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the > 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 consolidating them in > <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. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> (...) Yours sincerely, Vincent Mailhol
diff --git a/drivers/clk/at91/clk-peripheral.c b/drivers/clk/at91/clk-peripheral.c index c173a44c800aa8cc..60208bdc3fe4797e 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 4fb29ca111f7d427..3838e4f7df2d4a70 100644 --- a/drivers/clk/at91/pmc.h +++ b/drivers/clk/at91/pmc.h @@ -116,9 +116,6 @@ struct at91_clk_pms { unsigned int parent; }; -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) -#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) diff --git a/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c b/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c index 2e4095c4c12c94f9..ebaa59e934178309 100644 --- a/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c +++ b/drivers/crypto/intel/qat/qat_common/adf_gen4_pm_debugfs.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0-only /* Copyright(c) 2023 Intel Corporation */ +#include <linux/bitfield.h> #include <linux/dma-mapping.h> #include <linux/kernel.h> #include <linux/string_helpers.h> @@ -11,13 +12,6 @@ #include "adf_gen4_pm.h" #include "icp_qat_fw_init_admin.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. - */ -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) - #define PM_INFO_MEMBER_OFF(member) \ (offsetof(struct icp_qat_fw_init_admin_pm_info, member) / sizeof(u32)) diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c index 40c1bd80f8b0434d..b45e4dd8d8e4f00a 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/clk.h> #include <linux/gpio/aspeed.h> #include <linux/gpio/driver.h> @@ -30,10 +31,6 @@ #include <linux/gpio/consumer.h> #include "gpiolib.h" -/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */ -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) -#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 diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c index 740018d4b3dfb35e..c58dc59d4f570831 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> @@ -68,10 +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() */ -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) -#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 */ diff --git a/drivers/pinctrl/nuvoton/pinctrl-ma35.c b/drivers/pinctrl/nuvoton/pinctrl-ma35.c index 59c4e7c6cddea127..3ba28faa8e1418a9 100644 --- a/drivers/pinctrl/nuvoton/pinctrl-ma35.c +++ b/drivers/pinctrl/nuvoton/pinctrl-ma35.c @@ -81,10 +81,6 @@ #define MVOLT_1800 0 #define MVOLT_3300 1 -/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */ -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) -#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", diff --git a/drivers/soc/renesas/rz-sysc.c b/drivers/soc/renesas/rz-sysc.c index 1c98da37b7d18745..917a029d849585cd 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/io.h> #include <linux/of.h> #include <linux/platform_device.h> @@ -12,8 +13,6 @@ #include "rz-sysc.h" -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) - /** * struct rz_sysc - RZ SYSC private data structure * @base: SYSC base address diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h index 63928f1732230700..c62324a9fcc81241 100644 --- a/include/linux/bitfield.h +++ b/include/linux/bitfield.h @@ -203,4 +203,38 @@ __MAKE_OP(64) #undef __MAKE_OP #undef ____MAKE_OP +/** + * field_prep() - prepare a bitfield element + * @_mask: shifted mask defining the field's length and position + * @_val: value to put in the field + * + * 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. + */ +#define field_prep(_mask, _val) \ + ({ \ + typeof(_mask) __mask = (_mask); \ + unsigned int __shift = sizeof(_mask) <= 4 ? \ + __ffs(__mask) : __ffs64(__mask); \ + (((typeof(_mask))(_val) << __shift) & (__mask)); \ + }) + +/** + * field_get() - extract a bitfield element + * @_mask: shifted mask defining the field's length and position + * @_reg: value of entire bitfield + * + * 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. + */ +#define field_get(_mask, _reg) \ + ({ \ + typeof(_mask) __mask = _mask; \ + unsigned int __shift = sizeof(_mask) <= 4 ? \ + __ffs(__mask) : __ffs64(__mask); \ + (typeof(_mask))(((_reg) & (__mask)) >> __shift); \ + }) + #endif diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c index 23fcd680167d0298..00ab811e4b11a573 100644 --- a/sound/usb/mixer_quirks.c +++ b/sound/usb/mixer_quirks.c @@ -3109,10 +3109,6 @@ 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 */ -#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1)) -#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);
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 consolidating them in <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. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- 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 --- drivers/clk/at91/clk-peripheral.c | 1 + drivers/clk/at91/pmc.h | 3 -- .../qat/qat_common/adf_gen4_pm_debugfs.c | 8 +---- drivers/gpio/gpio-aspeed.c | 5 +-- drivers/iio/temperature/mlx90614.c | 5 +-- drivers/pinctrl/nuvoton/pinctrl-ma35.c | 4 --- drivers/soc/renesas/rz-sysc.c | 3 +- include/linux/bitfield.h | 34 +++++++++++++++++++ sound/usb/mixer_quirks.c | 4 --- 9 files changed, 39 insertions(+), 28 deletions(-)