[U-Boot] [PATCH 2/3] arm: mx31: use common timer functions

[Marek Vasut]

On Tuesday, August 12, 2014 at 04:26:00 PM, andrew.ruder at elecsyscorp.com wrote:
> From: Andrew Ruder <andrew.ruder at elecsyscorp.com>
> 
> This patch moves mx31 to the common timer functions added in commit
> 
>   8dfafdd - Introduce common timer functions <Rob Herring>
> 
> The (removed) mx31 timer code (specifically __udelay()) could deadlock at
> the 32-bit boundary of get_ticks().  get_ticks() returned a 32-bit value
> cast up to a 64-bit value.  If get_ticks() + tmo in __udelay() crossed
> the 32-bit boundary, the while condition became unconditionally true and
> locks the processor.  Rather than patch the specific mx31 issues, simply
> move everything over to the common code.
> 
> Signed-off-by: Andrew Ruder <andrew.ruder at elecsyscorp.com>
> Cc: Marek Vasut <marex at denx.de>
> Cc: Linus Walleij <linus.walleij at linaro.org>
> Cc: Wolfgang Denk <wd at denx.de>
> Cc: Fabio Estevam <fabio.estevam at freescale.com>
> Cc: Helmut Raiger <helmut.raiger at hale.at>

+CC Stefano 

> ---
> 
> This patch has been COMPILE tested only.  The situation isn't quite as
> bad on mx31 as 32-bit rollover occurs in about a day and a half.
> 
> Before patch:
> Configuring for qong board...
> 456 -rw-r--r-- 1 andy andy 463236 Aug 12 08:36 u-boot.bin
> 
> After patch:
> Configuring for qong board...
> 456 -rw-r--r-- 1 andy andy 463248 Aug 12 08:38 u-boot.bin
> 
>  arch/arm/cpu/arm1136/mx31/timer.c         | 104
> +----------------------------- arch/arm/include/asm/arch-mx31/imx-regs.h |
>  10 +++
>  2 files changed, 12 insertions(+), 102 deletions(-)
> 
> diff --git a/arch/arm/cpu/arm1136/mx31/timer.c
> b/arch/arm/cpu/arm1136/mx31/timer.c index f111242..3a81ce4 100644
> --- a/arch/arm/cpu/arm1136/mx31/timer.c
> +++ b/arch/arm/cpu/arm1136/mx31/timer.c
> @@ -7,9 +7,6 @@
> 
>  #include <common.h>
>  #include <asm/arch/imx-regs.h>
> -#include <asm/arch/clock.h>
> -#include <div64.h>
> -#include <watchdog.h>
>  #include <asm/io.h>
> 
>  #define TIMER_BASE 0x53f90000 /* General purpose timer 1 */
> @@ -28,57 +25,6 @@
> 
>  DECLARE_GLOBAL_DATA_PTR;
> 
> -/*
> - * "time" is measured in 1 / CONFIG_SYS_HZ seconds,
> - * "tick" is internal timer period
> - */
> -
> -#ifdef CONFIG_MX31_TIMER_HIGH_PRECISION
> -/* ~0.4% error - measured with stop-watch on 100s boot-delay */
> -static inline unsigned long long tick_to_time(unsigned long long tick)
> -{
> -	tick *= CONFIG_SYS_HZ;
> -	do_div(tick, MXC_CLK32);
> -	return tick;
> -}
> -
> -static inline unsigned long long time_to_tick(unsigned long long time)
> -{
> -	time *= MXC_CLK32;
> -	do_div(time, CONFIG_SYS_HZ);
> -	return time;
> -}
> -
> -static inline unsigned long long us_to_tick(unsigned long long us)
> -{
> -	us = us * MXC_CLK32 + 999999;
> -	do_div(us, 1000000);
> -	return us;
> -}
> -#else
> -/* ~2% error */
> -#define TICK_PER_TIME	((MXC_CLK32 + CONFIG_SYS_HZ / 2) / CONFIG_SYS_HZ)
> -#define US_PER_TICK	(1000000 / MXC_CLK32)
> -
> -static inline unsigned long long tick_to_time(unsigned long long tick)
> -{
> -	do_div(tick, TICK_PER_TIME);
> -	return tick;
> -}
> -
> -static inline unsigned long long time_to_tick(unsigned long long time)
> -{
> -	return time * TICK_PER_TIME;
> -}
> -
> -static inline unsigned long long us_to_tick(unsigned long long us)
> -{
> -	us += US_PER_TICK - 1;
> -	do_div(us, US_PER_TICK);
> -	return us;
> -}
> -#endif
> -
>  /* The 32768Hz 32-bit timer overruns in 131072 seconds */
>  int timer_init(void)
>  {
> @@ -95,53 +41,7 @@ int timer_init(void)
>  	return 0;
>  }
> 
> -unsigned long long get_ticks(void)
> -{
> -	ulong now = GPTCNT; /* current tick value */
> -
> -	if (now >= gd->arch.lastinc)	/* normal mode (non roll) */
> -		/* move stamp forward with absolut diff ticks */
> -		gd->arch.tbl += (now - gd->arch.lastinc);
> -	else			/* we have rollover of incrementer */
> -		gd->arch.tbl += (0xFFFFFFFF - gd->arch.lastinc) + now;
> -	gd->arch.lastinc = now;
> -	return gd->arch.tbl;
> -}
> -
> -ulong get_timer_masked(void)
> -{
> -	/*
> -	 * get_ticks() returns a long long (64 bit), it wraps in
> -	 * 2^64 / MXC_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
> -	 * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
> -	 * 5 * 10^6 days - long enough.
> -	 */
> -	return tick_to_time(get_ticks());
> -}
> -
> -ulong get_timer(ulong base)
> -{
> -	return get_timer_masked() - base;
> -}
> -
> -/* delay x useconds AND preserve advance timestamp value */
> -void __udelay(unsigned long usec)
> -{
> -	unsigned long long tmp;
> -	ulong tmo;
> -
> -	tmo = us_to_tick(usec);
> -	tmp = get_ticks() + tmo;	/* get current timestamp */
> -
> -	while (get_ticks() < tmp)	/* loop till event */
> -		 /*NOP*/;
> -}
> -
> -/*
> - * This function is derived from PowerPC code (timebase clock frequency).
> - * On ARM it returns the number of timer ticks per second.
> - */
> -ulong get_tbclk(void)
> +unsigned long timer_read_counter(void)
>  {
> -	return MXC_CLK32;
> +	return GPTCNT;
>  }
> diff --git a/arch/arm/include/asm/arch-mx31/imx-regs.h
> b/arch/arm/include/asm/arch-mx31/imx-regs.h index f23350e..71ebd24 100644
> --- a/arch/arm/include/asm/arch-mx31/imx-regs.h
> +++ b/arch/arm/include/asm/arch-mx31/imx-regs.h
> @@ -909,9 +909,19 @@ struct esdc_regs {
>  #define MXC_CSPIPERIOD_32KHZ	(1 << 15)
>  #define MAX_SPI_BYTES	4
> 
> +
>  #define MXC_SPI_BASE_ADDRESSES \
>  	0x43fa4000, \
>  	0x50010000, \
>  	0x53f84000,
> 
> +/*
> + * Generic timer support
> + */
> +#ifdef CONFIG_MX31_CLK32
> +#define	CONFIG_SYS_TIMER_RATE	CONFIG_MX31_CLK32
> +#else
> +#define	CONFIG_SYS_TIMER_RATE	32768
> +#endif
> +
>  #endif /* __ASM_ARCH_MX31_IMX_REGS_H */