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; + + return false; +} + #endif diff --git a/arch/arm/mach-at91/include/mach/early_udelay.h b/arch/arm/mach-at91/include/mach/early_udelay.h new file mode 100644 index 000000000000..120b586310f0 --- /dev/null +++ b/arch/arm/mach-at91/include/mach/early_udelay.h @@ -0,0 +1,13 @@ +#ifndef __EARLY_UDELAY_H__ +#define __EARLY_UDELAY_H__ + +#include <linux/compiler.h> + +/* requires PIT to be initialized, but not the clocksource framework */ +void early_udelay(unsigned int usec); +void early_udelay_init(void __iomem *pmc_base, + void __iomem *pit_base, + unsigned clock, + unsigned int master_clock_rate); + +#endif -- 2.20.1 _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
