Re: [RFC] clock: incorporate dummy clocksource into core clock code

[Sascha Hauer <s.hauer@pengutronix.de>]

On Tue, Dec 02, 2014 at 03:03:28AM +0300, Antony Pavlov wrote:
> Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
> ---
>  common/clock.c               | 20 ++++++++++++++--
>  drivers/clocksource/Kconfig  | 27 ++++++++--------------
>  drivers/clocksource/Makefile |  1 -
>  drivers/clocksource/dummy.c  | 55 --------------------------------------------
>  4 files changed, 28 insertions(+), 75 deletions(-)

Applied, thanks

Sascha

> 
> diff --git a/common/clock.c b/common/clock.c
> index 2ee81da..35c9e6c 100644
> --- a/common/clock.c
> +++ b/common/clock.c
> @@ -22,6 +22,7 @@
>   */
>  
>  #include <common.h>
> +#include <init.h>
>  #include <asm-generic/div64.h>
>  #include <clock.h>
>  #include <poller.h>
> @@ -35,6 +36,16 @@ static uint64_t time_ns;
>   */
>  uint64_t time_beginning;
>  
> +static int dummy_csrc_warn(void)
> +{
> +	if (!current_clock) {
> +		pr_warn("Warning: Using dummy clocksource\n");
> +	}
> +
> +	return 0;
> +}
> +late_initcall(dummy_csrc_warn);
> +
>  /**
>   * get_time_ns - get current timestamp in nanoseconds
>   */
> @@ -44,8 +55,13 @@ uint64_t get_time_ns(void)
>  	uint64_t cycle_now, cycle_delta;
>  	uint64_t ns_offset;
>  
> -	if (!cs)
> -		return 0;
> +	if (!cs) {
> +		static uint64_t dummy_counter;
> +
> +		dummy_counter += CONFIG_CLOCKSOURCE_DUMMY_RATE;
> +
> +		return dummy_counter;
> +	}
>  
>  	/* read clocksource: */
>  	cycle_now = cs->read() & cs->mask;
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index fc5a389..598edc9 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -18,28 +18,21 @@ config CLOCKSOURCE_DIGIC
>  	bool
>  	depends on ARCH_DIGIC
>  
> -config CLOCKSOURCE_DUMMY
> -	bool "Enable dummy software-only clocksource"
> +config CLOCKSOURCE_DUMMY_RATE
> +	int
> +	prompt "dummy clocksource rate"
> +	default 1000
>  	help
>  	  When porting barebox to a new SoC there might be a case
>  	  of broken or absent clocksource. This causes barebox serial
>  	  console to be non functional.
> -	  To solve the problem this software-only clocksource driver is used.
> -	      WARNING!!! This clocksource doesn't provide correct timing.
> -	  To adjust this clocksource please use CONFIG_CLOCKSOURCE_DUMMY_RATE.
> +	  To solve the problem barebox has built-in software-only clocksource.
> +	  The software-only clocksource is used only if no hardware clocksource
> +	  is registered. This can help if initialization order is wrong so that
> +	  the time functions are used before the real clocksource was initialized.
> +	      WARNING!!! Built-in software-only clocksource doesn't provide correct timing.
> +	  The option CONFIG_CLOCKSOURCE_DUMMY_RATE is used to adjust this clocksource.
>  	  The bigger rate valuest makes clocksource "faster".
> -	  It's possible to add this clocksource unconditionally.
> -	  This clocksource starts very early (pure_initcall) so
> -	  real clocksource will take over.
> -	  This can help if initialization order is wrong so that
> -	  the time functions are used before the real clocksource
> -	  was initialized.
> -
> -config CLOCKSOURCE_DUMMY_RATE
> -	int
> -	prompt "dummy clocksource rate"
> -	depends on CLOCKSOURCE_DUMMY
> -	default 1000
>  
>  config CLOCKSOURCE_MVEBU
>  	bool
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index b80df6b..f5f5141 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -3,7 +3,6 @@ obj-$(CONFIG_ARM_SMP_TWD) += arm_smp_twd.o
>  obj-$(CONFIG_CLOCKSOURCE_BCM2835) += bcm2835.o
>  obj-$(CONFIG_CLOCKSOURCE_CLPS711X) += clps711x.o
>  obj-$(CONFIG_CLOCKSOURCE_DIGIC)   += digic.o
> -obj-$(CONFIG_CLOCKSOURCE_DUMMY)   += dummy.o
>  obj-$(CONFIG_CLOCKSOURCE_MVEBU)   += mvebu.o
>  obj-$(CONFIG_CLOCKSOURCE_NOMADIK) += nomadik.o
>  obj-$(CONFIG_CLOCKSOURCE_ORION)   += orion.o
> diff --git a/drivers/clocksource/dummy.c b/drivers/clocksource/dummy.c
> deleted file mode 100644
> index 96f9b6e..0000000
> --- a/drivers/clocksource/dummy.c
> +++ /dev/null
> @@ -1,55 +0,0 @@
> -/*
> - * Copyright (C) 2013 Antony Pavlov <antonynpavlov@gmail.com>
> - *
> - * This file is part of barebox.
> - * See file CREDITS for list of people who contributed to this project.
> - *
> - * This program is free software; you can redistribute it and/or modify
> - * it under the terms of the GNU General Public License version 2
> - * as published by the Free Software Foundation.
> - *
> - * This program is distributed in the hope that it will be useful,
> - * but WITHOUT ANY WARRANTY; without even the implied warranty of
> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> - * GNU General Public License for more details.
> - *
> - */
> -
> -#include <common.h>
> -#include <init.h>
> -#include <clock.h>
> -
> -static uint64_t dummy_counter;
> -
> -static uint64_t dummy_cs_read(void)
> -{
> -	static int first;
> -
> -	if (!first) {
> -		pr_warn("Warning: Using dummy clocksource\n");
> -		first = 1;
> -	}
> -
> -	dummy_counter += CONFIG_CLOCKSOURCE_DUMMY_RATE;
> -
> -	return dummy_counter;
> -}
> -
> -static struct clocksource dummy_cs = {
> -	.read	= dummy_cs_read,
> -	.mask   = CLOCKSOURCE_MASK(32),
> -};
> -
> -static int clocksource_init(void)
> -{
> -	dummy_counter = 0;
> -
> -	clocks_calc_mult_shift(&dummy_cs.mult, &dummy_cs.shift,
> -		100000000, NSEC_PER_SEC, 10);
> -
> -	pr_debug("clocksource_init: mult=%08x, shift=%08x\n",
> -			dummy_cs.mult, dummy_cs.shift);
> -
> -	return init_clock(&dummy_cs);
> -}
> -pure_initcall(clocksource_init);
> -- 
> 2.1.3
> 
> 

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