linux-stable/drivers/pwm
Uwe Kleine-König 0491709eb3 pwm: lpc18xx: Fix period handling
[ Upstream commit 8933d30c5f ]

The calculation:

	val = (u64)NSEC_PER_SEC * LPC18XX_PWM_TIMER_MAX;
	do_div(val, lpc18xx_pwm->clk_rate);
	lpc18xx_pwm->max_period_ns = val;

is bogus because with NSEC_PER_SEC = 1000000000,
LPC18XX_PWM_TIMER_MAX = 0xffffffff and clk_rate < NSEC_PER_SEC this
overflows the (on lpc18xx (i.e. ARM32) 32 bit wide) unsigned int
.max_period_ns. This results (dependant of the actual clk rate) in an
arbitrary limitation of the maximal period.  E.g. for clkrate =
333333333 (Hz) we get max_period_ns = 9 instead of 12884901897.

So make .max_period_ns an u64 and pass period and duty as u64 to not
discard relevant digits. And also make use of mul_u64_u64_div_u64()
which prevents all overflows assuming clk_rate < NSEC_PER_SEC.

Fixes: 841e6f90bb ("pwm: NXP LPC18xx PWM/SCT driver")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-08-17 14:23:16 +02:00
..
core.c
Kconfig
Makefile
pwm-ab8500.c
pwm-atmel-hlcdc.c
pwm-atmel-tcb.c
pwm-atmel.c
pwm-bcm-iproc.c
pwm-bcm-kona.c
pwm-bcm2835.c
pwm-berlin.c
pwm-brcmstb.c
pwm-clps711x.c
pwm-crc.c
pwm-cros-ec.c
pwm-dwc.c
pwm-ep93xx.c
pwm-fsl-ftm.c
pwm-hibvt.c
pwm-img.c
pwm-imx-tpm.c
pwm-imx1.c
pwm-imx27.c
pwm-intel-lgm.c
pwm-iqs620a.c
pwm-jz4740.c
pwm-keembay.c
pwm-lp3943.c
pwm-lpc18xx-sct.c pwm: lpc18xx: Fix period handling 2022-08-17 14:23:16 +02:00
pwm-lpc32xx.c
pwm-lpss-pci.c
pwm-lpss-platform.c
pwm-lpss.c
pwm-lpss.h
pwm-mediatek.c
pwm-meson.c
pwm-mtk-disp.c
pwm-mxs.c
pwm-ntxec.c
pwm-omap-dmtimer.c
pwm-pca9685.c
pwm-pxa.c
pwm-raspberrypi-poe.c
pwm-rcar.c
pwm-renesas-tpu.c
pwm-rockchip.c
pwm-samsung.c
pwm-sifive.c pwm: sifive: Shut down hardware only after pwmchip_remove() completed 2022-08-17 14:23:15 +02:00
pwm-sl28cpld.c
pwm-spear.c
pwm-sprd.c
pwm-sti.c
pwm-stm32-lp.c
pwm-stm32.c
pwm-stmpe.c
pwm-sun4i.c
pwm-tegra.c
pwm-tiecap.c
pwm-tiehrpwm.c
pwm-twl-led.c
pwm-twl.c
pwm-visconti.c
pwm-vt8500.c
sysfs.c