[PATCH v2] time: Fix get_ticks being non-monotonic

[Sean Anderson <seanga2@gmail.com>]

On 3/1/21 11:40 AM, Michael Opdenacker wrote:
> Hi Simon,
> 
> I'm back working on this old issue. Thanks for your help with this!
> 
> So, SPL support for Atmel/Microchip SAMA5D3 is still broken in the
> latest mainline, at least for the Xplained board with the MMC configuration.
> 
> My comments and further questions below...
> 
> On 11/22/20 12:07 AM, Simon Glass wrote:
>> Hi Michael,
>>
>> On Thu, 19 Nov 2020 at 04:23, Michael Opdenacker
>> <michael.opdenacker@bootlin.com> wrote:
>>> Hi,
>>>
>>> Sorry, no messaging quoting, I was not subscribed to the list at that time.
>>>
>>> Merging this change into master actually broke the SPL on
>>> Atmel/Microchip SAMA5D3, at least booting from MMC:
>>>
>>> RomBOOT
>>>
>>> <debug_uart>
>>> Could not initialize timer (err -11)
>>>
>>> Could not initialize timer (err -11)
>>>
>>> Could not initialize timer (err -11)
>>> ...
>>>
>>> I'll look for a fix, but suggestions are welcome!
> 
> 
> Now, it's:
> 
> Could not initialize timer (err -19)
> (-19 is -ENODEV  /* No such device */)
> 
>> The board might need CONFIG_TIMER_EARLY, but otherwise I think it is a
>> case of figuring out why the timer is used before it is available.
> 
> 
> I tried to enable CONFIG_TIMER_EARLY but it fails at link time:
> 
>    LD      u-boot
> arm-linux-ld.bfd: lib/built-in.o: in function `get_tbclk':
> /home/mike/work/git/git.denx.de/u-boot/lib/time.c:70: undefined
> reference to `timer_early_get_rate'
> arm-linux-ld.bfd: lib/built-in.o: in function `get_ticks':
> /home/mike/work/git/git.denx.de/u-boot/lib/time.c:90: undefined
> reference to `timer_early_get_count'
> make: *** [Makefile:1765: u-boot] Error 1
> 
> 
> This is not a surprise, as according to
> https://elixir.bootlin.com/u-boot/latest/C/ident/timer_early_get_rate,
> timer_early_get_rate() is not implemented on ARM, only on sandbox
> (drivers/timer/sandbox_timer.c) and on x86 (drivers/timer/tsc_timer.c).

It is also available on most RISC-V boards, not that it helps :)

> 
> So, I'm moving to your second suggestion...
> 
> 
>>
>> You can use dm_dump_all() to print out available devices and whether
>> they are probed.
> 
> 
> Done, I added dm_dump_all to lib/time.c right before the panic() message:
> 
>   Class     Index  Probed  Driver                Name
> -----------------------------------------------------------
>   root  0  [ + ]   root_driver  root_driver
>   simple_bus  0  [   ]   simple_bus  `-- ahb
>   simple_bus  1  [   ]   simple_bus      `-- apb
>   mmc  0  [   ]   atmel-mci          |-- mmc at f0000000
>   blk  0  [   ]   mmc_blk          |   `-- mmc at f0000000.blk
>   mmc  1  [   ]   atmel-mci          |-- mmc at f8000000
>   blk  1  [   ]   mmc_blk          |   `-- mmc at f8000000.blk
>   serial  0  [   ]   serial_atmel          |-- serial at ffffee00
>   pinctrl  0  [   ]   atmel_sama5d3_pinctrl          |-- pinctrl at fffff200
>   pinconfig  0  [   ]   pinconfig          |   |-- dbgu
>   pinconfig  1  [   ]   pinconfig          |   |   `-- dbgu-0
>   pinconfig  2  [   ]   pinconfig          |   |-- mmc0
>   pinconfig  3  [   ]   pinconfig          |   |   |-- mmc0_clk_cmd_dat0
>   pinconfig  4  [   ]   pinconfig          |   |   |-- mmc0_dat1_3
>   pinconfig  5  [   ]   pinconfig          |   |   `-- mmc0_dat4_7
>   pinconfig  6  [   ]   pinconfig          |   |-- mmc1
>   pinconfig  7  [   ]   pinconfig          |   |   |-- mmc1_clk_cmd_dat0
>   pinconfig  8  [   ]   pinconfig          |   |   `-- mmc1_dat1_3
>   pinconfig  9  [   ]   pinconfig          |   |-- spi0
>   pinconfig  10  [   ]   pinconfig          |   |   `-- spi0-0
>   pinconfig  11  [   ]   pinconfig          |   |-- spi1
>   pinconfig  12  [   ]   pinconfig          |   |   `-- spi1-0
>   pinconfig  13  [   ]   pinconfig          |   `-- board
>   pinconfig  14  [   ]   pinconfig          |       |-- mmc0_cd
>   pinconfig  15  [   ]   pinconfig          |       `-- mmc1_cd
>   gpio  0  [   ]   atmel_at91rm9200_gpio          |-- gpio at fffff200
>   gpio  1  [   ]   atmel_at91rm9200_gpio          |-- gpio at fffff400
>   gpio  2  [   ]   atmel_at91rm9200_gpio          |-- gpio at fffff600
>   gpio  3  [   ]   atmel_at91rm9200_gpio          |-- gpio at fffff800
>   gpio  4  [   ]   atmel_at91rm9200_gpio          |-- gpio at fffffa00
>   simple_bus  2  [   ]   at91-pmc          `-- pmc at fffffc00
>   clk  0  [   ]   at91sam9x5-utmi-clk              |-- utmick
>   clk  1  [   ]   at91-master-clk              |-- masterck
>   misc  0  [   ]   sam9x5-periph-clk              `-- periphck
>   clk  2  [   ]   periph-clk                  |-- dbgu_clk at 2
>   clk  3  [   ]   periph-clk                  |-- pioA_clk at 6
>   clk  4  [   ]   periph-clk                  |-- pioB_clk at 7
>   clk  5  [   ]   periph-clk                  |-- pioC_clk at 8
>   clk  6  [   ]   periph-clk                  |-- pioD_clk at 9
>   clk  7  [   ]   periph-clk                  |-- pioE_clk at 10
>   clk  8  [   ]   periph-clk                  |-- mci0_clk at 21
>   clk  9  [   ]   periph-clk                  |-- mci1_clk at 22
>   clk  10  [   ]   periph-clk                  |-- spi0_clk at 24
>   clk  11  [   ]   periph-clk                  `-- spi1_clk at 25
> Could not initialize timer (err -19)

So nothing here is probed, but additionally nothing has UCLASS_TIMER.
What do you expect the timer device to be?

--Sean

> 
> I'm not familiar enough with U-Boot yet (and with SAMA5D3 support
> either) to see why the timer device is missing here, but I hope our
> Microchip friends can give us further clues...
> 
> Thanks again,
> 
> Cheers,
> 
> Michael.
>