On Wed, Feb 20, 2019 at 10:20:32AM +0100, Sascha Hauer wrote: > On Tue, Feb 19, 2019 at 06:21:41PM +0100, Ahmad Fatoum wrote: > > For use by the incoming at91bootstrap DDRAMC initialization code, > > this commit provides an early_udelay function usable in PBL imported from > > https://github.com/linux4sam/at91bootstrap/blob/v3.8.12/driver/at91_pit.c > > > > Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> > > --- > > arch/arm/mach-at91/Makefile | 1 + > > arch/arm/mach-at91/early_udelay.c | 53 +++++++++++++++++++ > > .../include/mach/at91_lowlevel_clock.h | 9 ++++ > > .../arm/mach-at91/include/mach/early_udelay.h | 13 +++++ > > 4 files changed, 76 insertions(+) > > create mode 100644 arch/arm/mach-at91/early_udelay.c > > create mode 100644 arch/arm/mach-at91/include/mach/early_udelay.h > > > > diff --git a/arch/arm/mach-at91/Makefile b/arch/arm/mach-at91/Makefile > > index 7c4c58b080a1..b8ff6428d05a 100644 > > --- a/arch/arm/mach-at91/Makefile > > +++ b/arch/arm/mach-at91/Makefile > > @@ -1,5 +1,6 @@ > > obj-y += setup.o > > pbl-y += lowlevel_clock.o > > +pbl-$(CONFIG_CLOCKSOURCE_ATMEL_PIT) += early_udelay.o > > > > ifeq ($(CONFIG_COMMON_CLK_OF_PROVIDER),) > > obj-y += clock.o > > diff --git a/arch/arm/mach-at91/early_udelay.c b/arch/arm/mach-at91/early_udelay.c > > new file mode 100644 > > index 000000000000..fb8d8bba5434 > > --- /dev/null > > +++ b/arch/arm/mach-at91/early_udelay.c > > @@ -0,0 +1,53 @@ > > +// SPDX-License-Identifier: BSD-1-Clause > > +/* > > + * Copyright (c) 2012, Atmel Corporation > > + */ > > + > > +#include <mach/hardware.h> > > +#include <asm/io.h> > > +#include <mach/at91_lowlevel_clock.h> > > +#include <mach/at91_pit.h> > > +#include <mach/early_udelay.h> > > + > > +static unsigned int master_clock; > > +static void __iomem *pmc, *pit; > > + > > +/* Because the below statement is used in the function: > > + * ((MASTER_CLOCK >> 10) * usec) is used, > > + * to our 32-bit system. the argu "usec" maximum value is: > > + * supposed "MASTER_CLOCK" is 132M. > > + * 132000000 / 1024 = 128906 > > + * (0xffffffff) / 128906 = 33318. > > + * So the maximum delay time is 33318 us. > > + */ > > +/* requires PIT to be initialized, but not the clocksource framework */ > > +void early_udelay(unsigned int usec) > > +{ > > + unsigned int delay; > > + unsigned int current; > > + unsigned int base = readl(pit + AT91_PIT_PIIR); > > + > > + if (at91_pmc_check_mck_h32mxdiv(pmc)) > > + master_clock /= 2; > > + > > + delay = ((master_clock >> 10) * usec) >> 14; > > + > > + do { > > + current = readl(pit + AT91_PIT_PIIR); > > + current -= base; > > + } while (current < delay); > > +} > > + > > +void early_udelay_init(void __iomem *pmc_base, > > + void __iomem *pit_base, > > + unsigned clock, > > + unsigned int master_clock_rate) > > +{ > > + master_clock = master_clock_rate; > > + pmc = pmc_base; > > + pit = pit_base; > > + > > + writel(AT91_PIT_PIV | AT91_PIT_PITEN, pit + AT91_PIT_MR); > > + > > + at91_pmc_enable_periph_clock(pmc_base, clock); > > +} > > diff --git a/arch/arm/mach-at91/include/mach/at91_lowlevel_clock.h b/arch/arm/mach-at91/include/mach/at91_lowlevel_clock.h > > index 8d04e30b644b..e4bdaade740c 100644 > > --- a/arch/arm/mach-at91/include/mach/at91_lowlevel_clock.h > > +++ b/arch/arm/mach-at91/include/mach/at91_lowlevel_clock.h > > @@ -9,6 +9,7 @@ > > #include <errno.h> > > #include <asm/io.h> > > #include <mach/at91_pmc.h> > > +#include <linux/types.h> > > > > void at91_lowlevel_clock_init(void __iomem *pmc_base); > > void at91_pmc_cfg_mck(void __iomem *pmc_base, u32 pmc_mckr); > > @@ -40,4 +41,12 @@ static inline int at91_pmc_enable_periph_clock(void __iomem *pmc_base, > > return 0; > > } > > > > +static inline bool at91_pmc_check_mck_h32mxdiv(void __iomem *pmc_base) > > +{ > > + if (IS_ENABLED(CONFIG_HAVE_AT91_H32MX)) > > + return readl(pmc_base + AT91_PMC_MCKR) & AT91_PMC_H32MXDIV; > > Okay, here's another build time dependency on the SoC type. In this case > early_udelay_init() would need a flag whether to apply this additional > divider or not. Even better create SoC specific variants of > early_udelay_init() to make it more convenient for the caller. Another thing worth considering: The accuracy of early_udelay is probably not critical. Maybe you could in doubt simply use the longer delay. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
