| Message ID | cover.1637592133.git.geert+renesas@glider.be (mailing list archive) |
|---|---|
| Headers | show |
| Series | Non-const bitfield helper conversions | expand |
Hi Alexandre, On Mon, Nov 22, 2021 at 6:50 PM Alexandre Belloni <alexandre.belloni@bootlin.com> wrote: > On 22/11/2021 16:53:53+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 already has its own > > field_{prep,get}() macros. > > My understanding was that this (being compile time only) was actually > done on purpose. Did I misunderstand? Yes, it was done on purpose, to maximize type safety. However, this imposes a severe limitation: we cannot use them in case the mask is non-const (i.e. stored in some data structure). This is a quite common use-case, given the examples I found and converted, and given you added field_{get,prep}() to the AT91 clock driver. 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
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. I have already submitted a few conversions to the FIELD_{GET,PREP}() helpers that were fixes for real bugs: - [PATCH] mips: cm: Convert to bitfield API to fix out-of-bounds access https://lore.kernel.org/r/0471c545117c5fa05bd9c73005cda9b74608a61e.1635501373.git.geert+renesas@glider.be - [PATCH] drm/armada: Fix off-by-one error in armada_overlay_get_property() https://lore.kernel.org/r/5818c8b04834e6a9525441bc181580a230354b69.1635501237.git.geert+renesas@glider.be Plus several patches for normal conversions: - [PATCH] ARM: ptrace: Use bitfield helpers https://lore.kernel.org/r/a1445d3abb45cfc95cb1b03180fd53caf122035b.1637593297.git.geert+renesas@glider.be - [PATCH] MIPS: CPC: Use bitfield helpers https://lore.kernel.org/r/35f0f17e3d987afaa9cd09cdcb8131d42a53c3e1.1637593297.git.geert+renesas@glider.be - [PATCH] MIPS: CPS: Use bitfield helpers https://lore.kernel.org/r/8bd8b1b9a3787e594285addcf2057754540d0a5f.1637593297.git.geert+renesas@glider.be - [PATCH] crypto: sa2ul - Use bitfield helpers https://lore.kernel.org/r/ca89d204ef2e40193479db2742eadf0d9cf3c0ff.1637593297.git.geert+renesas@glider.be - [PATCH] dmaengine: stm32-mdma: Use bitfield helpers https://lore.kernel.org/r/36ceab242a594233dc7dc6f1dddb4ac32d1e846f.1637593297.git.geert+renesas@glider.be - [PATCH] intel_th: Use bitfield helpers https://lore.kernel.org/r/b1e4f027aa88acfbdfaa771b0920bd1d977828ba.1637593297.git.geert+renesas@glider.be - [PATCH] Input: palmas-pwrbutton - use bitfield helpers https://lore.kernel.org/r/f8831b88346b36fc6e01e0910d0db6c94287d2b4.1637593297.git.geert+renesas@glider.be - [PATCH] irqchip/mips-gic: Use bitfield helpers https://lore.kernel.org/r/74f9d126961a90d3e311b92a54870eaac5b3ae57.1637593297.git.geert+renesas@glider.be - [PATCH] mfd: mc13xxx: Use bitfield helpers https://lore.kernel.org/r/afa46868cf8c1666e9cbbbec42767ca2294b024d.1637593297.git.geert+renesas@glider.be - [PATCH] regulator: lp873x: Use bitfield helpers https://lore.kernel.org/r/44d60384b640c8586b4ca7edbc9287a34ce21c5b.1637593297.git.geert+renesas@glider.be - [PATCH] regulator: lp87565: Use bitfield helpers https://lore.kernel.org/r/941c2dfd5b5b124b8950bcce42db4c343dfe9821.1637593297.git.geert+renesas@glider.be 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 already has its own field_{prep,get}() macros. This patch series makes them available for general use, and converts several drivers to the existing FIELD_{GET,PREP}() and the new field_{get,prep}() helpers. I can take the first two patches through the reneas-clk tree for v5.17, but probably it is best for the remaining patches to be postponed to v5.18. Thanks for your comments! Geert Uytterhoeven (17): bitfield: Add non-constant field_{prep,get}() helpers clk: renesas: Use bitfield helpers [RFC] soc: renesas: Use bitfield helpers [RFC] ARM: OMAP2+: Use bitfield helpers [RFC] bus: omap_l3_noc: Use bitfield helpers [RFC] clk: ti: Use bitfield helpers [RFC] iio: st_sensors: Use bitfield helpers [RFC] iio: humidity: hts221: Use bitfield helpers [RFC] iio: imu: st_lsm6dsx: Use bitfield helpers [RFC] media: ti-vpe: cal: Use bitfield helpers [RFC] mmc: sdhci-of-aspeed: Use bitfield helpers [RFC] pinctrl: aspeed: Use bitfield helpers [RFC] pinctl: ti: iodelay: Use bitfield helpers [RFC] regulator: ti-abb: Use bitfield helpers [RFC] thermal/ti-soc-thermal: Use bitfield helpers [RFC] ALSA: ice1724: Use bitfield helpers [RFC] rtw89: Use bitfield helpers arch/arm/mach-omap2/clkt2xxx_dpllcore.c | 5 +- arch/arm/mach-omap2/cm2xxx.c | 11 ++- arch/arm/mach-omap2/cm2xxx_3xxx.h | 9 +-- arch/arm/mach-omap2/cm33xx.c | 9 +-- arch/arm/mach-omap2/cm3xxx.c | 7 +- arch/arm/mach-omap2/cminst44xx.c | 9 +-- arch/arm/mach-omap2/powerdomains3xxx_data.c | 3 +- arch/arm/mach-omap2/prm.h | 2 - arch/arm/mach-omap2/prm2xxx.c | 4 +- arch/arm/mach-omap2/prm2xxx_3xxx.c | 7 +- arch/arm/mach-omap2/prm2xxx_3xxx.h | 9 +-- arch/arm/mach-omap2/prm33xx.c | 53 +++++------- arch/arm/mach-omap2/prm3xxx.c | 3 +- arch/arm/mach-omap2/prm44xx.c | 53 ++++-------- arch/arm/mach-omap2/vc.c | 12 +-- arch/arm/mach-omap2/vp.c | 11 +-- drivers/bus/omap_l3_noc.c | 4 +- drivers/clk/at91/clk-peripheral.c | 1 + drivers/clk/at91/pmc.h | 3 - drivers/clk/renesas/clk-div6.c | 6 +- drivers/clk/renesas/r8a779a0-cpg-mssr.c | 9 +-- drivers/clk/renesas/rcar-gen3-cpg.c | 15 ++-- drivers/clk/ti/apll.c | 25 +++--- drivers/clk/ti/dpll3xxx.c | 81 ++++++++----------- .../iio/common/st_sensors/st_sensors_core.c | 5 +- drivers/iio/humidity/hts221_core.c | 8 +- drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h | 1 - .../iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c | 7 +- drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c | 45 +++++------ drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c | 11 +-- drivers/media/platform/ti-vpe/cal.h | 4 +- drivers/mmc/host/sdhci-of-aspeed.c | 5 +- drivers/net/wireless/realtek/rtw89/core.h | 38 ++------- drivers/pinctrl/aspeed/pinctrl-aspeed-g4.c | 3 +- drivers/pinctrl/aspeed/pinctrl-aspeed-g5.c | 3 +- drivers/pinctrl/aspeed/pinctrl-aspeed-g6.c | 3 +- drivers/pinctrl/aspeed/pinctrl-aspeed.c | 5 +- drivers/pinctrl/aspeed/pinmux-aspeed.c | 6 +- drivers/pinctrl/ti/pinctrl-ti-iodelay.c | 35 +++----- drivers/regulator/ti-abb-regulator.c | 7 +- drivers/soc/renesas/renesas-soc.c | 4 +- drivers/thermal/ti-soc-thermal/ti-bandgap.c | 11 ++- include/linux/bitfield.h | 30 +++++++ sound/pci/ice1712/wm8766.c | 14 ++-- sound/pci/ice1712/wm8776.c | 14 ++-- 45 files changed, 263 insertions(+), 347 deletions(-)