[U-Boot] [RESEND PATCH v2 2/5] Tegra2: Add microsecond timer functions

[Albert ARIBAUD]

Hi Simon,

Le 05/07/2011 18:49, Simon Glass a écrit :
> These functions provide access to the high resolution microsecond timer
> and tidy up a global variable in the code.
>
> Signed-off-by: Simon Glass<sjg at chromium.org>
> ---
>   arch/arm/cpu/armv7/tegra2/timer.c        |   27 +++++++++++++++++------
>   arch/arm/include/asm/arch-tegra2/timer.h |   34 ++++++++++++++++++++++++++++++
>   2 files changed, 54 insertions(+), 7 deletions(-)
>   create mode 100644 arch/arm/include/asm/arch-tegra2/timer.h
>
> diff --git a/arch/arm/cpu/armv7/tegra2/timer.c b/arch/arm/cpu/armv7/tegra2/timer.c
> index fb061d0..b69c172 100644
> --- a/arch/arm/cpu/armv7/tegra2/timer.c
> +++ b/arch/arm/cpu/armv7/tegra2/timer.c
> @@ -38,13 +38,12 @@
>   #include<common.h>
>   #include<asm/io.h>
>   #include<asm/arch/tegra2.h>
> +#include<asm/arch/timer.h>
>
>   DECLARE_GLOBAL_DATA_PTR;
>
> -struct timerus *timer_base = (struct timerus *)NV_PA_TMRUS_BASE;
> -
>   /* counter runs at 1MHz */
> -#define TIMER_CLK	(1000000)
> +#define TIMER_CLK	1000000
>   #define TIMER_LOAD_VAL	0xffffffff
>
>   /* timer without interrupts */
> @@ -67,10 +66,10 @@ void set_timer(ulong t)
>   void __udelay(unsigned long usec)
>   {
>   	long tmo = usec * (TIMER_CLK / 1000) / 1000;
> -	unsigned long now, last = readl(&timer_base->cntr_1us);
> +	unsigned long now, last = timer_get_us();
>
>   	while (tmo>  0) {
> -		now = readl(&timer_base->cntr_1us);
> +		now = timer_get_us();
>   		if (last>  now) /* count up timer overflow */
>   			tmo -= TIMER_LOAD_VAL - last + now;
>   		else
> @@ -82,7 +81,7 @@ void __udelay(unsigned long usec)
>   void reset_timer_masked(void)
>   {
>   	/* reset time, capture current incrementer value time */
> -	gd->lastinc = readl(&timer_base->cntr_1us) / (TIMER_CLK/CONFIG_SYS_HZ);
> +	gd->lastinc = timer_get_us() / (TIMER_CLK/CONFIG_SYS_HZ);
>   	gd->tbl = 0;		/* start "advancing" time stamp from 0 */
>   }
>
> @@ -91,7 +90,7 @@ ulong get_timer_masked(void)
>   	ulong now;
>
>   	/* current tick value */
> -	now = readl(&timer_base->cntr_1us) / (TIMER_CLK / CONFIG_SYS_HZ);
> +	now = timer_get_us() / (TIMER_CLK / CONFIG_SYS_HZ);
>
>   	if (now>= gd->lastinc)	/* normal mode (non roll) */
>   		/* move stamp forward with absolute diff ticks */
> @@ -120,3 +119,17 @@ ulong get_tbclk(void)
>   {
>   	return CONFIG_SYS_HZ;
>   }
> +
> +
> +unsigned long timer_get_us(void)
> +{
> +	struct timerus *timer_base = (struct timerus *)NV_PA_TMRUS_BASE;
> +
> +	return readl(&timer_base->cntr_1us);
> +}
> +
> +unsigned long timer_get_future_us(u32 delay)
> +{
> +	return timer_get_us() + delay;
> +}

What is the added value in a function that just adds its argument to the 
return value of another function? Might as well do the addition directly 
instead of calling this 'future' function.

> +
> diff --git a/arch/arm/include/asm/arch-tegra2/timer.h b/arch/arm/include/asm/arch-tegra2/timer.h
> new file mode 100644
> index 0000000..5d5445e
> --- /dev/null
> +++ b/arch/arm/include/asm/arch-tegra2/timer.h
> @@ -0,0 +1,34 @@
> +/*
> + * Copyright (c) 2011 The Chromium OS Authors.
> + * 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 as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> + * MA 02111-1307 USA
> + */
> +
> +/* Tegra2 timer functions */
> +
> +#ifndef _TEGRA2_TIMER_H
> +#define _TEGRA2_TIMER_H
> +
> +/* returns the current monotonic timer value in microseconds */
> +unsigned long timer_get_us(void);
> +
> +/* returns what the time will likely be some microseconds into the future */
> +unsigned long timer_get_future_us(u32 delay);
> +
> +#endif
> +


Amicalement,
-- 
Albert.