[U-Boot] [PATCH v3 05/11] dm: timer: Support 64-bit counter
Bin Meng
bmeng.cn at gmail.com
Mon Nov 16 03:19:34 CET 2015
Hi Simon,
On Sat, Nov 14, 2015 at 10:04 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Bin,
>
> On 13 November 2015 at 01:11, Bin Meng <bmeng.cn at gmail.com> wrote:
>> There are timers with a 64-bit counter value but current timer
>> uclass driver assumes a 32-bit one. Modify timer_get_count()
>> to ask timer driver to always return a 64-bit counter value,
>> and provide an inline helper function timer_conv_64() to handle
>> the 32-bit/64-bit conversion automatically.
>>
>> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
>>
>> ---
>>
>> Changes in v3:
>> - Update commit message to reflect the v2 changes (ie: there is
>> no "counter-64bit" property)
>>
>> Changes in v2:
>> - Do not use "counter-64bit" property, instead create an inline
>> function for 32-bit timer driver to construct a 64-bit timer value.
>>
>> drivers/timer/altera_timer.c | 4 ++--
>> drivers/timer/sandbox_timer.c | 2 +-
>> drivers/timer/timer-uclass.c | 8 +++-----
>> include/timer.h | 23 ++++++++++++++++++++---
>> lib/time.c | 9 ++++++---
>> 5 files changed, 32 insertions(+), 14 deletions(-)
>
> Is there a binding file for this timer somewhere? If both altera and
> sandbox share this property, should we add a generic binding? It
> doesn't look like Linux has one though.
>
>>
>> diff --git a/drivers/timer/altera_timer.c b/drivers/timer/altera_timer.c
>> index 6fe24f2..a7ed3cc 100644
>> --- a/drivers/timer/altera_timer.c
>> +++ b/drivers/timer/altera_timer.c
>> @@ -34,7 +34,7 @@ struct altera_timer_platdata {
>> struct altera_timer_regs *regs;
>> };
>>
>> -static int altera_timer_get_count(struct udevice *dev, unsigned long *count)
>> +static int altera_timer_get_count(struct udevice *dev, u64 *count)
>> {
>> struct altera_timer_platdata *plat = dev->platdata;
>> struct altera_timer_regs *const regs = plat->regs;
>> @@ -46,7 +46,7 @@ static int altera_timer_get_count(struct udevice *dev, unsigned long *count)
>> /* Read timer value */
>> val = readl(®s->snapl) & 0xffff;
>> val |= (readl(®s->snaph) & 0xffff) << 16;
>> - *count = ~val;
>> + *count = timer_conv_64(~val);
>>
>> return 0;
>> }
>> diff --git a/drivers/timer/sandbox_timer.c b/drivers/timer/sandbox_timer.c
>> index 4b20af2..00a9944 100644
>> --- a/drivers/timer/sandbox_timer.c
>> +++ b/drivers/timer/sandbox_timer.c
>> @@ -18,7 +18,7 @@ void sandbox_timer_add_offset(unsigned long offset)
>> sandbox_timer_offset += offset;
>> }
>>
>> -static int sandbox_timer_get_count(struct udevice *dev, unsigned long *count)
>> +static int sandbox_timer_get_count(struct udevice *dev, u64 *count)
>> {
>> *count = os_get_nsec() / 1000 + sandbox_timer_offset * 1000;
>>
>> diff --git a/drivers/timer/timer-uclass.c b/drivers/timer/timer-uclass.c
>> index 0218591..1ef0012 100644
>> --- a/drivers/timer/timer-uclass.c
>> +++ b/drivers/timer/timer-uclass.c
>> @@ -9,18 +9,16 @@
>> #include <errno.h>
>> #include <timer.h>
>>
>> -DECLARE_GLOBAL_DATA_PTR;
>> -
>> /*
>> * Implement a timer uclass to work with lib/time.c. The timer is usually
>> - * a 32 bits free-running up counter. The get_rate() method is used to get
>> + * a 32/64 bits free-running up counter. The get_rate() method is used to get
>> * the input clock frequency of the timer. The get_count() method is used
>> - * to get the current 32 bits count value. If the hardware is counting down,
>> + * to get the current 64 bits count value. If the hardware is counting down,
>> * the value should be inversed inside the method. There may be no real
>> * tick, and no timer interrupt.
>> */
>>
>> -int timer_get_count(struct udevice *dev, unsigned long *count)
>> +int timer_get_count(struct udevice *dev, u64 *count)
>> {
>> const struct timer_ops *ops = device_get_ops(dev);
>>
>> diff --git a/include/timer.h b/include/timer.h
>> index ed5c685..4eed504 100644
>> --- a/include/timer.h
>> +++ b/include/timer.h
>> @@ -7,6 +7,23 @@
>> #ifndef _TIMER_H_
>> #define _TIMER_H_
>>
>> +DECLARE_GLOBAL_DATA_PTR;
>> +
>> +/*
>> + * timer_conv_64 - convert 32-bit counter value to 64-bit
>> + *
>> + * @count: 32-bit counter value
>> + * @return: 64-bit counter value
>> + */
>> +static inline u64 timer_conv_64(u32 count)
>> +{
>> + /* increment tbh if tbl has rolled over */
>> + if (count < gd->timebase_l)
>> + gd->timebase_h++;
>> + gd->timebase_l = count;
>> + return ((u64)gd->timebase_h << 32) | gd->timebase_l;
>> +}
>> +
>> /*
>> * Get the current timer count
>> *
>> @@ -14,7 +31,7 @@
>> * @count: pointer that returns the current timer count
>> * @return: 0 if OK, -ve on error
>> */
>> -int timer_get_count(struct udevice *dev, unsigned long *count);
>> +int timer_get_count(struct udevice *dev, u64 *count);
>>
>> /*
>> * Get the timer input clock frequency
>> @@ -35,10 +52,10 @@ struct timer_ops {
>> * Get the current timer count
>> *
>> * @dev: The timer device
>> - * @count: pointer that returns the current timer count
>> + * @count: pointer that returns the current 64-bit timer count
>> * @return: 0 if OK, -ve on error
>> */
>> - int (*get_count)(struct udevice *dev, unsigned long *count);
>> + int (*get_count)(struct udevice *dev, u64 *count);
>
> Why do we need to change the API to 64-bit?
IMHO, this API should be created to be accept a 64-bit value in the
first place. As you see the U-Boot time APIs in lib/time.c like
get_ticks() has been using 64-bit value.
>
> My only concern is that we are pretty happy with the 32-bit timer and
> I'm not sure it should change. At present unsigned long can be 32-bit
> on 32-bit machines.
32-bit timer has to be converted to 64-bit value as get_ticks()
requires 64-bit. As for 'unsigned long can be 32-bit on 32-bit
machines', I think we should explicitly declare its width as this is
hardware limitation (32-bit timer can only produce 32-bit value, even
if it is on a 64-bit machine, where long on 64-bit means 64-bit, which
is wrong for this 32-bit timer hardware).
>
>> };
>>
>> /*
>> diff --git a/lib/time.c b/lib/time.c
>> index b001745..f37a662 100644
>> --- a/lib/time.c
>> +++ b/lib/time.c
>> @@ -69,9 +69,9 @@ ulong notrace get_tbclk(void)
>> return timer_get_rate(gd->timer);
>> }
>>
>> -unsigned long notrace timer_read_counter(void)
>> +uint64_t notrace get_ticks(void)
>> {
>> - unsigned long count;
>> + u64 count;
>> int ret;
>>
>> ret = dm_timer_init();
>> @@ -84,7 +84,8 @@ unsigned long notrace timer_read_counter(void)
>>
>> return count;
>> }
>> -#endif /* CONFIG_TIMER */
>> +
>> +#else /* !CONFIG_TIMER */
>>
>> uint64_t __weak notrace get_ticks(void)
>> {
>> @@ -97,6 +98,8 @@ uint64_t __weak notrace get_ticks(void)
>> return ((uint64_t)gd->timebase_h << 32) | gd->timebase_l;
>> }
>>
>> +#endif /* CONFIG_TIMER */
>> +
>> /* Returns time in milliseconds */
>> static uint64_t notrace tick_to_time(uint64_t tick)
>> {
>> --
Regards,
Bin
More information about the U-Boot
mailing list