Re: [RFC PATCH 2/3] net: macb: Add support for 1588 for Zynq Ultrascale+ MPSoC

[Michal Simek]

Hi Nicolas,

just a note: Here is the link to public Linux repo
https://github.com/Xilinx/linux-xlnx

Thanks,
Michal


On 9.8.2016 18:56, Punnaiah Choudary Kalluri wrote:
> Hi Nicolas,
> 
>  1588 implementation in cadence GEM IP we have in Zynq Ultascale+ MPSoC is
> Different to the one in Zynq SOC.
> 
> In earlier version, all timestamp values will be stored in registers and there is no specific
> Mechanism to distinguish the received ethernet frame that contains time stamp information
> Other than parsing the frame for PTP packet type.
> 
> We have basic implementation for earlier version in our out of tree driver, which is going to be deprecated
> Soon. You could also check the below driver for 1588 support.
> https://gitenterprise.xilinx.com/Linux/linux-xlnx/blob/master/drivers/net/ethernet/xilinx/xilinx_emacps.c
> 
> 
> Regards,
> Punnaiah
> 
>> -----Original Message-----
>> From: Nicolas Ferre [mailto:nicolas.ferre@xxxxxxxxx]
>> Sent: Tuesday, August 09, 2016 10:10 PM
>> To: Harini Katakam <harinikatakamlinux@xxxxxxxxx>; Harini Katakam
>> <harinik@xxxxxxxxxx>; Andrei Pistirica <Andrei.Pistirica@xxxxxxxxxxxxx>
>> Cc: davem@xxxxxxxxxxxxx; Boris Brezillon <boris.brezillon@free-
>> electrons.com>; alexandre.belloni@xxxxxxxxxxxxxxxxxx;
>> netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
>> devicetree@xxxxxxxxxxxxxxx; Punnaiah Choudary Kalluri
>> <punnaia@xxxxxxxxxx>; Michal Simek <michals@xxxxxxxxxx>; Anirudha
>> Sarangi <anirudh@xxxxxxxxxx>
>> Subject: Re: [RFC PATCH 2/3] net: macb: Add support for 1588 for Zynq
>> Ultrascale+ MPSoC
>>
>> Le 21/09/2015 Ã 19:49, Harini Katakam a Ãcrit :
>>> On Fri, Sep 11, 2015 at 1:27 PM, Harini Katakam
>>> <harini.katakam@xxxxxxxxxx> wrote:
>>>> Cadence GEM in Zynq Ultrascale+ MPSoC supports 1588 and provides a
>>>> 102 bit time counter with 48 bits for seconds, 30 bits for nsecs and
>>>> 24 bits for sub-nsecs. The timestamp is made available to the SW through
>>>> registers as well as (more precisely) through upper two words in
>>>> an extended BD.
>>>>
>>>> This patch does the following:
>>>> - Adds MACB_CAPS_TSU in zynqmp_config.
>>>> - Registers to ptp clock framework (after checking for timestamp support
>> in
>>>>   IP and capability in config).
>>>> - TX BD and RX BD control registers are written to populate timestamp in
>>>>   extended BD words.
>>>> - Timer initialization is done by writing time of day to the timer counter.
>>>> - ns increment register is programmed as NS_PER_SEC/TSU_CLK.
>>>>   For a 24 bit subns precision, the subns increment equals
>>>>   remainder of (NS_PER_SEC/TSU_CLK) * (2^24).
>>>>   TSU (Time stamp unit) clock is obtained by the  driver from devicetree.
>>>> - HW time stamp capabilities are advertised via ethtool and macb ioctl is
>>>>   updated accordingly.
>>>> - For all PTP event frames, nanoseconds and the lower 5 bits of seconds
>> are
>>>>   obtained from the BD. This offers a precise timestamp. The upper bits
>>>>   (which dont vary between consecutive packets) are obtained from the
>>>>   TX/RX PTP event/PEER registers. The timestamp obtained thus is
>> updated
>>>>   in skb for upper layers to access.
>>>> - The drivers register functions with ptp to perform time and frequency
>>>>   adjustment.
>>>> - Time adjustment is done by writing to the 1558_ADJUST register.
>>>>   The controller will read the delta in this register and update the timer
>>>>   counter register. Alternatively, for large time offset adjustments,
>>>>   the driver reads the secs and nsecs counter values, adds/subtracts the
>>>>   delta and updates the timer counter. In order to be as precise as
>> possible,
>>>>   nsecs counter is read again if secs has incremented during the counter
>> read.
>>>> - Frequency adjustment is not directly supported by this IP.
>>>>   addend is the initial value ns increment and similarly addendesub.
>>>>   The ppb (parts per billion) provided is used as
>>>>   ns_incr = addend +/- (ppb/rate).
>>>>   Similarly the remainder of the above is used to populate subns
>> increment.
>>>>   In case the ppb requested is negative AND subns adjustment greater
>> than
>>>>   the addendsub, ns_incr is reduced by 1 and subns_incr is adjusted in
>>>>   positive accordingly.
>>>>
>>>> Signed-off-by: Harini Katakam <harinik@xxxxxxxxxx>:
>>>> ---
>>>>  drivers/net/ethernet/cadence/macb.c |  372
>> ++++++++++++++++++++++++++++++++++-
>>>>  drivers/net/ethernet/cadence/macb.h |   64 ++++++
>>>>  2 files changed, 428 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/drivers/net/ethernet/cadence/macb.c
>> b/drivers/net/ethernet/cadence/macb.c
>>>> index bb2932c..b531008 100644
>>>> --- a/drivers/net/ethernet/cadence/macb.c
>>>> +++ b/drivers/net/ethernet/cadence/macb.c
>>>> @@ -30,6 +30,8 @@
>>>>  #include <linux/of_device.h>
>>>>  #include <linux/of_mdio.h>
>>
>> [..]
>>
>>>> +       unsigned int            ns_incr;
>>>> +       unsigned int            subns_incr;
>>>>  };
>>>>
>>>>  static inline bool macb_is_gem(struct macb *bp)
>>>> --
>>>> 1.7.9.5
>>>
>>> Ping
>>>
>>> Thanks.
>>
>> Harini,
>>
>> I come back to this patch of last year and I'm sorry about being so late
>> answering you.
>>
>> Andrei who is added to the discussion will have some time to deal with
>> this feature and we would like to make some progress with it. He already
>> had some work done on his side before I recall your email.
>>
>> So, could you please re-send your original 1588 patch with Andrei in
>> copy so that we can all (re-)start the discussion and progress for
>> adding this feature.
>>
>> We must also note that some hardware differences between our platforms
>> may have an impact on the code and how we implement things (as
>> highlighted on this forum:
>> http://www.at91.com/discussions/viewtopic.php/f,12/t,25462.html).
>> Anyway, we'll overcome this and have a widely tested solution at the end
>> of the day!
>>
>> Thanks for your patience, bye!
>>
>> PS: for some reason, I only have this "ping" part of your email but not
>> the original one
>> --
>> Nicolas Ferre