Re: [PATCH v3 6/8] coresight-tpdm: Add timestamp control register support for the CMB

From: Suzuki K Poulose
Date: Mon Jan 08 2024 - 05:43:03 EST

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On 05/01/2024 07:49, Tao Zhang wrote:

On 12/30/2023 5:39 PM, Suzuki K Poulose wrote:

On 25/12/2023 01:55, Tao Zhang wrote:

On 12/20/2023 7:07 PM, Suzuki K Poulose wrote:

On 20/12/2023 09:51, Tao Zhang wrote:

On 12/19/2023 9:51 PM, Suzuki K Poulose wrote:

On 19/12/2023 02:43, Tao Zhang wrote:

On 12/18/2023 6:46 PM, Suzuki K Poulose wrote:

On 21/11/2023 02:24, Tao Zhang wrote:

CMB_TIER register is CMB subunit timestamp insertion enable register.
Bit 0 is PATT_TSENAB bit. Set this bit to 1 to request a timestamp
following a CMB interface pattern match. Bit 1 is XTRIG_TSENAB bit.
Set this bit to 1 to request a timestamp following a CMB CTI timestamp
request. Bit 2 is TS_ALL bit. Set this bit to 1 to request timestamp
for all packets.

Reviewed-by: James Clark <james.clark@xxxxxxx>
Signed-off-by: Tao Zhang <quic_taozha@xxxxxxxxxxx>
Signed-off-by: Jinlong Mao <quic_jinlmao@xxxxxxxxxxx>
---
.../testing/sysfs-bus-coresight-devices-tpdm | 35 ++++++
drivers/hwtracing/coresight/coresight-tpdm.c | 116 +++++++++++++++++-
drivers/hwtracing/coresight/coresight-tpdm.h | 14 +++
3 files changed, 162 insertions(+), 3 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
index 53662ce7c2d0..e0b77107be13 100644
--- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
+++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
@@ -214,3 +214,38 @@ KernelVersion    6.7
Contact:    Jinlong Mao (QUIC) <quic_jinlmao@xxxxxxxxxxx>, Tao Zhang (QUIC) <quic_taozha@xxxxxxxxxxx>
Description:
          (RW) Set/Get the mask of the pattern for the CMB subunit TPDM.
+
+What: /sys/bus/coresight/devices/<tpdm-name>/cmb_patt/enable_ts
+Date:        September 2023
+KernelVersion    6.7
+Contact:    Jinlong Mao (QUIC) <quic_jinlmao@xxxxxxxxxxx>, Tao Zhang (QUIC) <quic_taozha@xxxxxxxxxxx>
+Description:
+        (Write) Set the pattern timestamp of CMB tpdm. Read
+        the pattern timestamp of CMB tpdm.
+
+        Accepts only one of the 2 values - 0 or 1.
+        0 : Disable CMB pattern timestamp.
+        1 : Enable CMB pattern timestamp.
+
+What: /sys/bus/coresight/devices/<tpdm-name>/cmb_trig_ts
+Date:        September 2023
+KernelVersion    6.7
+Contact:    Jinlong Mao (QUIC) <quic_jinlmao@xxxxxxxxxxx>, Tao Zhang (QUIC) <quic_taozha@xxxxxxxxxxx>
+Description:
+        (RW) Set/Get the trigger timestamp of the CMB for tpdm.
+
+        Accepts only one of the 2 values - 0 or 1.
+        0 : Set the CMB trigger type to false
+        1 : Set the CMB trigger type to true
+
+What: /sys/bus/coresight/devices/<tpdm-name>/cmb_ts_all
+Date:        September 2023
+KernelVersion    6.7
+Contact:    Jinlong Mao (QUIC) <quic_jinlmao@xxxxxxxxxxx>, Tao Zhang (QUIC) <quic_taozha@xxxxxxxxxxx>
+Description:
+        (RW) Read or write the status of timestamp upon all interface.
+        Only value 0 and 1 can be written to this node. Set this node to 1 to requeset
+        timestamp to all trace packet.
+        Accepts only one of the 2 values - 0 or 1.
+        0 : Disable the timestamp of all trace packets.
+        1 : Enable the timestamp of all trace packets.
diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c b/drivers/hwtracing/coresight/coresight-tpdm.c
index 894d4309f1c7..f6cda5616e84 100644
--- a/drivers/hwtracing/coresight/coresight-tpdm.c
+++ b/drivers/hwtracing/coresight/coresight-tpdm.c
@@ -331,6 +331,36 @@ static void tpdm_enable_dsb(struct tpdm_drvdata *drvdata)
      writel_relaxed(val, drvdata->base + TPDM_DSB_CR);
}
+static void set_cmb_tier(struct tpdm_drvdata *drvdata)
+{
+    u32 val;
+
+    val = readl_relaxed(drvdata->base + TPDM_CMB_TIER);
+
+    /* Clear all relevant fields */
+    val &= ~(TPDM_CMB_TIER_PATT_TSENAB | TPDM_CMB_TIER_TS_ALL |
+         TPDM_CMB_TIER_XTRIG_TSENAB);
+
+    /* Set pattern timestamp type and enablement */
+    if (drvdata->cmb->patt_ts)
+        val |= TPDM_CMB_TIER_PATT_TSENAB;

-- cut --

+    else
+        val &= ~TPDM_CMB_TIER_PATT_TSENAB;

All the else cases in this function are superfluous. Please remove all
of them.

I will update this in the next patch.

+
+    /* Set trigger timestamp */
+    if (drvdata->cmb->trig_ts)
+        val |= TPDM_CMB_TIER_XTRIG_TSENAB;
+    else
+        val &= ~TPDM_CMB_TIER_XTRIG_TSENAB;
+
+    /* Set all timestamp enablement*/
+    if (drvdata->cmb->ts_all)
+        val |= TPDM_CMB_TIER_TS_ALL;
+    else
+        val &= ~TPDM_CMB_TIER_TS_ALL;
+    writel_relaxed(val, drvdata->base + TPDM_CMB_TIER);
+}
+
static void tpdm_enable_cmb(struct tpdm_drvdata *drvdata)
{
      u32 val, i;
@@ -347,6 +377,8 @@ static void tpdm_enable_cmb(struct tpdm_drvdata *drvdata)
                  drvdata->base + TPDM_CMB_XPMR(i));
      }
+    set_cmb_tier(drvdata);
+
      val = readl_relaxed(drvdata->base + TPDM_CMB_CR);
      /*
       * Set to 0 for continuous CMB collection mode,
@@ -695,9 +727,17 @@ static ssize_t enable_ts_show(struct device *dev,
                    char *buf)
{
      struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+    ssize_t size = 0;
-    return sysfs_emit(buf, "%u\n",
-             (unsigned int)drvdata->dsb->patt_ts);
+    if (tpdm_has_dsb_dataset(drvdata))
+        size = sysfs_emit(buf, "%u\n",
+                 (unsigned int)drvdata->dsb->patt_ts);
+
+    if (tpdm_has_cmb_dataset(drvdata))
+        size = sysfs_emit(buf, "%u\n",
+                 (unsigned int)drvdata->cmb->patt_ts);

Why does this need to show two values ? This must only show ONE value.
How you deduce that might be based on the availability of the feature
set. Or store the TS value in the drvdata and use that instead for
controlling CMB/DSB.

Since both of CMB/DSB need to have "enable_ts" SysFs file, can I separate them

The question really is, do we need fine grained control. i.e.,

enable TS for DSB but not for CMB or vice versa.

I am not an expert on the usage scenario of the same. So, if you/Qcomm
thinks the users need separate, fine grained control for timestamp
for the DSB and CMB, then yes, follow your recommendation below.
i.e., tpdm.../dsb_patt/enable_ts

as "enable_dsb_ts" and "enable_cmb_ts"? The path will be like below.

tpdm0/dsb_patt/enable_dsb_ts

You don't need enable_dsb_ts. It could be "enable_ts"

tpdm1/cmb_patt/enable_cmb_ts

Is this design appropriate?

Otherwise, stick to single enable_ts : which enables the ts for both
CMB/DSB. And it only ever show one value : 0 (TS is disabled for both
CMB/DSB) 1 : TS enabled for both.

We have a very special case, such as the TPDM supporting both CMB and

DSB datasets. Although this case is very rare, it still exists.

Can I use the data bit to instruct whether timestamp is enabled for CMB/DSB or not? For example,

size = sysfs_emit(buf, "%u\n",
                 (unsigned int)(drvdata->dsb->patt_ts << 1 | drvdata->cmb->patt_ts));

Thus, this value can instruct the following situations.

0 - TS is disabled for both CMB/DSB

1 - TS is enabled for CMB

2 - TS is enabled for DSB

3 - TS is enabled for both

Is this approach acceptable?

No, please stick to separate controls for TS. Do not complicate
the user interface.

i.e.,
tpdm0/dsb_patt/enable_ts
tpdm0/cmb_patt/enable_ts

We need to be able to control/show dsb and cmb timestamp enablement independently.

Can we achieve this requirement if we use a sysfs file with the same name?

They are independent and in their respective directory (group) for CMB and DSB. What am I missing ?
e.g., if you want to enable TS for DSB, you do :

$ echo 1 > dsb_patt/enable_ts

And that only works for DSB not for CMB.

We have a special case that the TPDM supports both DSB and CMB dataset. In this special case, when we

issue this command to enable timestamp, it will call enable_ts_store API, right?

    if (tpdm_has_dsb_dataset(drvdata))
       drvdata->dsb->patt_ts = !!val;

   if (tpdm_has_cmb_dataset(drvdata))
       drvdata->cmb->patt_ts = !!val;

I don't understand. If they both are under different subgroups, why
should they be conflicting ? Are you not able to distinguish them, when
you creat those attributes ? i.e., create two different "attributes" ?

See below.

Since this special TPDM supports both DSB and CMB dataset, both DSB patt_ts and CMB patt_ts will be set

in this case even if I only configure the file in the DSB directory, right?

This is the problem we have now.

+
+    return size;
}
/*
@@ -715,8 +755,13 @@ static ssize_t enable_ts_store(struct device *dev,
          return -EINVAL;
      spin_lock(&drvdata->spinlock);
-    drvdata->dsb->patt_ts = !!val;
+    if (tpdm_has_dsb_dataset(drvdata))
+        drvdata->dsb->patt_ts = !!val;
+
+    if (tpdm_has_cmb_dataset(drvdata))
+        drvdata->cmb->patt_ts = !!val;
      spin_unlock(&drvdata->spinlock);
+
      return size;
}
static DEVICE_ATTR_RW(enable_ts);

Do not overload the same for both DSB and CMB. Create one for each in DSB and CMB ? They could share the same show/store routines, but could
be done with additional variable to indicate which attribute they are controlling. Like the other attributes, using dev_ext_attribute or such.

Suzuki

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