Re: [RFC PATCH 06/10] net: ti: prueth: Adds HW timestamping support for PTP using PRU-ICSS IEP module

[Basharath Hussain Khaja <basharath@couthit.com>]

> On Fri, Jan 10, 2025 at 2:01 PM Basharath Hussain Khaja
> <basharath@couthit.com> wrote:
>>
>> From: Roger Quadros <rogerq@ti.com>
>>
>> PRU-ICSS IEP module, which is capable of timestamping RX and
>> TX packets at HW level, is used for time synchronization by PTP4L.
>>
>> This change includes interaction between firmware and user space
>> application (ptp4l) with required packet timestamps. The driver
>> initializes the PRU firmware with appropriate mode and configuration
>> flags. Firmware updates local registers with the flags set by driver
>> and uses for further operation. RX SOF timestamp comes along with
>> packet and firmware will rise interrupt with TX SOF timestamp after
>> pushing the packet on to the wire.
>>
>> IEP driver is available in upstream and we are reusing for hardware
>> configuration for ICSSM as well. On top of that we have extended it
>> with the changes for AM57xx SoC.
>>
>> Extended ethtool for reading HW timestamping capability of the PRU
>> interfaces.
>>
>> Currently ordinary clock (OC) configuration has been validated with
>> Linux ptp4l.
>>
>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>> Signed-off-by: Andrew F. Davis <afd@ti.com>
>> Signed-off-by: Parvathi Pudi <parvathi@couthit.com>
>> Signed-off-by: Basharath Hussain Khaja <basharath@couthit.com>
>> ---
>>  drivers/net/ethernet/ti/icssg/icss_iep.c      |  42 ++
>>  drivers/net/ethernet/ti/icssm/icssm_ethtool.c |  26 +
>>  drivers/net/ethernet/ti/icssm/icssm_prueth.c  | 443 +++++++++++++++++-
>>  drivers/net/ethernet/ti/icssm/icssm_prueth.h  |  11 +
>>  .../net/ethernet/ti/icssm/icssm_prueth_ptp.h  |  85 ++++
>>  5 files changed, 605 insertions(+), 2 deletions(-)
>>  create mode 100644 drivers/net/ethernet/ti/icssm/icssm_prueth_ptp.h
>>
>> diff --git a/drivers/net/ethernet/ti/icssg/icss_iep.c
>> b/drivers/net/ethernet/ti/icssg/icss_iep.c
>> index 768578c0d958..9a2ea13703d8 100644
>> --- a/drivers/net/ethernet/ti/icssg/icss_iep.c
>> +++ b/drivers/net/ethernet/ti/icssg/icss_iep.c
>> @@ -937,11 +937,53 @@ static const struct icss_iep_plat_data
>> am654_icss_iep_plat_data = {
>>         .config = &am654_icss_iep_regmap_config,
>>  };
>>
>> +static const struct icss_iep_plat_data am57xx_icss_iep_plat_data = {
>> +       .flags = ICSS_IEP_64BIT_COUNTER_SUPPORT |
>> +                ICSS_IEP_SLOW_COMPEN_REG_SUPPORT,
>> +       .reg_offs = {
>> +               [ICSS_IEP_GLOBAL_CFG_REG] = 0x00,
>> +               [ICSS_IEP_COMPEN_REG] = 0x08,
>> +               [ICSS_IEP_SLOW_COMPEN_REG] = 0x0C,
>> +               [ICSS_IEP_COUNT_REG0] = 0x10,
>> +               [ICSS_IEP_COUNT_REG1] = 0x14,
>> +               [ICSS_IEP_CAPTURE_CFG_REG] = 0x18,
>> +               [ICSS_IEP_CAPTURE_STAT_REG] = 0x1c,
>> +
>> +               [ICSS_IEP_CAP6_RISE_REG0] = 0x50,
>> +               [ICSS_IEP_CAP6_RISE_REG1] = 0x54,
>> +
>> +               [ICSS_IEP_CAP7_RISE_REG0] = 0x60,
>> +               [ICSS_IEP_CAP7_RISE_REG1] = 0x64,
>> +
>> +               [ICSS_IEP_CMP_CFG_REG] = 0x70,
>> +               [ICSS_IEP_CMP_STAT_REG] = 0x74,
>> +               [ICSS_IEP_CMP0_REG0] = 0x78,
>> +               [ICSS_IEP_CMP0_REG1] = 0x7c,
>> +               [ICSS_IEP_CMP1_REG0] = 0x80,
>> +               [ICSS_IEP_CMP1_REG1] = 0x84,
>> +
>> +               [ICSS_IEP_CMP8_REG0] = 0xc0,
>> +               [ICSS_IEP_CMP8_REG1] = 0xc4,
>> +               [ICSS_IEP_SYNC_CTRL_REG] = 0x180,
>> +               [ICSS_IEP_SYNC0_STAT_REG] = 0x188,
>> +               [ICSS_IEP_SYNC1_STAT_REG] = 0x18c,
>> +               [ICSS_IEP_SYNC_PWIDTH_REG] = 0x190,
>> +               [ICSS_IEP_SYNC0_PERIOD_REG] = 0x194,
>> +               [ICSS_IEP_SYNC1_DELAY_REG] = 0x198,
>> +               [ICSS_IEP_SYNC_START_REG] = 0x19c,
>> +       },
>> +       .config = &am654_icss_iep_regmap_config,
>> +};
>> +
>>  static const struct of_device_id icss_iep_of_match[] = {
>>         {
>>                 .compatible = "ti,am654-icss-iep",
>>                 .data = &am654_icss_iep_plat_data,
>>         },
>> +       {
>> +               .compatible = "ti,am5728-icss-iep",
>> +               .data = &am57xx_icss_iep_plat_data,
>> +       },
>>         {},
>>  };
>>  MODULE_DEVICE_TABLE(of, icss_iep_of_match);
>> diff --git a/drivers/net/ethernet/ti/icssm/icssm_ethtool.c
>> b/drivers/net/ethernet/ti/icssm/icssm_ethtool.c
>> index cce3276d5565..86d62d64dc4d 100644
>> --- a/drivers/net/ethernet/ti/icssm/icssm_ethtool.c
>> +++ b/drivers/net/ethernet/ti/icssm/icssm_ethtool.c
>> @@ -7,6 +7,7 @@
>>
>>  #include <linux/if_bridge.h>
>>  #include "icssm_prueth.h"
>> +#include "../icssg/icss_iep.h"
>>
>>  #define PRUETH_MODULE_VERSION "0.2"
>>  #define PRUETH_MODULE_DESCRIPTION "PRUSS Ethernet driver"
>> @@ -189,12 +190,37 @@ static void icssm_emac_get_regs(struct net_device *ndev,
>>         regs->version = PRUETH_REG_DUMP_GET_VER(prueth);
>>  }
>>
>> +static int icssm_emac_get_ts_info(struct net_device *ndev,
>> +                                 struct kernel_ethtool_ts_info *info)
>> +{
>> +       struct prueth_emac *emac = netdev_priv(ndev);
>> +
>> +       if ((PRUETH_IS_EMAC(emac->prueth) && !emac->emac_ptp_tx_irq))
>> +               return ethtool_op_get_ts_info(ndev, info);
>> +
>> +       info->so_timestamping =
>> +               SOF_TIMESTAMPING_TX_HARDWARE |
>> +               SOF_TIMESTAMPING_TX_SOFTWARE |
>> +               SOF_TIMESTAMPING_RX_HARDWARE |
>> +               SOF_TIMESTAMPING_RX_SOFTWARE |
>> +               SOF_TIMESTAMPING_SOFTWARE |
>> +               SOF_TIMESTAMPING_RAW_HARDWARE;
> 
> In addtion to what Richard suggested, there is no need to re-mark the
> following flags "SOF_TIMESTAMPING_RX_SOFTWARE" and
> "SOF_TIMESTAMPING_SOFTWARE", please see __ethtool_get_ts_info().
> 

Yes. This module always uses IEP HW timestamping both on RX side and TX side 
for better precision. We will clean this in the next version.

Thanks & Best Regards,
Basharath