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. 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
