[U-Boot] [PATCH 4/8] nomadik_mtu: support configurable clock rates

[Tom <Tom.Rix@windriver.com>]

Rabin Vincent wrote:
> Change the Nomadik MTU driver to get the clock rate and prescaler from
> the config file.  Also remove the hardcoded divisors and do the
> calculations based on the configured rate.
> 
> Acked-by: Alessandro Rubini <rubini@unipv.it>
> Acked-by: Michael Brandt <michael.brandt@stericsson.com>
> Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
> ---
>  drivers/misc/nomadik_mtu.c |   22 +++++++++++++---------
>  include/configs/nhk8815.h  |    3 +++
>  2 files changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/misc/nomadik_mtu.c b/drivers/misc/nomadik_mtu.c
> index b9c0fb1..4ec75ad 100644
> --- a/drivers/misc/nomadik_mtu.c
> +++ b/drivers/misc/nomadik_mtu.c
> @@ -22,25 +22,29 @@
>  
>  #include <common.h>
>  #include <asm/io.h>
> +#include <div64.h>
>  #include <nomadik_mtu.h>
>  
> -/*
> - * The timer is a decrementer, we'll left it free running at 2.4MHz.
> - * We have 2.4 ticks per microsecond and an overflow in almost 30min
> - */
> -#define TIMER_CLOCK		(24 * 100 * 1000)
> -#define COUNT_TO_USEC(x)	((x) * 5 / 12)	/* overflows at 6min */
> -#define USEC_TO_COUNT(x)	((x) * 12 / 5)	/* overflows at 6min */
> +#define TIMER_CLOCK		CONFIG_NOMADIK_MTU_CLOCK
>  #define TICKS_PER_HZ		(TIMER_CLOCK / CONFIG_SYS_HZ)
>  #define TICKS_TO_HZ(x)		((x) / TICKS_PER_HZ)

TICKS_TO_HZ is only used once.
This macro should be expanded in get_timer() and removed

TICKS_PER_HZ is only used in TICKS_PER_HZ, it should be expanded and removed

TIMER_CLOCK is a remapping of CONFIG_NOMADIK_MTU_CLOCK.
CONFIG_NOMADIK_MTU_CLOCK should just be used

>  
>  /* macro to read the decrementing 32 bit timer as an increasing count */
>  #define READ_TIMER() (0 - readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0)))
>  
> +static unsigned long usec_to_count(unsigned long long usec)
> +{
> +	unsigned long long count = usec * TIMER_CLOCK;
> +
> +	do_div(count, 1000000);
> +
> +	return count;
> +}
> +
>  /* Configure a free-running, auto-wrap counter with no prescaler */
>  int timer_init(void)
>  {
> -	writel(MTU_CRn_ENA | MTU_CRn_PRESCALE_1 | MTU_CRn_32BITS,
> +	writel(MTU_CRn_ENA | CONFIG_NOMADIK_MTU_PRESCALE | MTU_CRn_32BITS,
>  	       CONFIG_SYS_TIMERBASE + MTU_CR(0));
>  	reset_timer();
>  	return 0;
> @@ -73,7 +77,7 @@ void __udelay(unsigned long usec)
>  	ulong ini, end;
>  
>  	ini = READ_TIMER();
> -	end = ini + USEC_TO_COUNT(usec);
> +	end = ini + usec_to_count(usec);
>  	while ((signed)(end - READ_TIMER()) > 0)
>  		;
>  }
> diff --git a/include/configs/nhk8815.h b/include/configs/nhk8815.h
> index 8ba1e5e..d52f50c 100644
> --- a/include/configs/nhk8815.h
> +++ b/include/configs/nhk8815.h
> @@ -98,6 +98,9 @@
>  #define CONFIG_SYS_HZ		1000 /* Mandatory... */
>  #define CONFIG_SYS_TIMERBASE	0x101E2000
>  #define CONFIG_NOMADIK_MTU
> +/* We have 2.4 ticks per microsecond and an overflow in almost 30min */
> +#define CONFIG_NOMADIK_MTU_CLOCK	(24 * 100 * 1000)
> +#define CONFIG_NOMADIK_MTU_PRESCALE	MTU_CRn_PRESCALE_1
>  
>  /* GPIO */
>  #define CONFIG_NOMADIK_GPIO

Tom