coresight: tmc-etr: Refactor for handling errors

Refactor the tmc-etr enable operation to make it easier to
handle errors in enabling the hardware. We need to make
sure that the buffer is compatible with the ETR. This
patch re-arranges to make the error handling easier, by
deferring the hardware enablement until all the errors
are checked. This also avoids turning the CATU on/off
during a sysfs read session.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 43 insertions, 24 deletions

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 56fea4ff947e..c42693542ec8 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -918,21 +918,10 @@ static void tmc_sync_etr_buf(struct tmc_drvdata *drvdata)
                 tmc_etr_buf_insert_barrier_packet(etr_buf, etr_buf->offset);
 }
 
-static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
-                              struct etr_buf *etr_buf)
+static void __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
 {
         u32 axictl, sts;
-
-        /* Callers should provide an appropriate buffer for use */
-        if (WARN_ON(!etr_buf || drvdata->etr_buf))
-                return;
-        drvdata->etr_buf = etr_buf;
-
-        /*
-         * If this ETR is connected to a CATU, enable it before we turn
-         * this on
-         */
-        tmc_etr_enable_catu(drvdata);
+        struct etr_buf *etr_buf = drvdata->etr_buf;
 
         CS_UNLOCK(drvdata->base);
 
@@ -952,11 +941,8 @@ static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
                 axictl |= TMC_AXICTL_ARCACHE_OS;
         }
 
-        if (etr_buf->mode == ETR_MODE_ETR_SG) {
-                if (WARN_ON(!tmc_etr_has_cap(drvdata, TMC_ETR_SG)))
-                        return;
+        if (etr_buf->mode == ETR_MODE_ETR_SG)
                 axictl |= TMC_AXICTL_SCT_GAT_MODE;
-        }
 
         writel_relaxed(axictl, drvdata->base + TMC_AXICTL);
         tmc_write_dba(drvdata, etr_buf->hwaddr);
@@ -982,6 +968,32 @@ static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
         CS_LOCK(drvdata->base);
 }
 
+static int tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
+                             struct etr_buf *etr_buf)
+{
+        /* Callers should provide an appropriate buffer for use */
+        if (WARN_ON(!etr_buf))
+                return -EINVAL;
+
+        if ((etr_buf->mode == ETR_MODE_ETR_SG) &&
+            WARN_ON(!tmc_etr_has_cap(drvdata, TMC_ETR_SG)))
+                return -EINVAL;
+
+        if (WARN_ON(drvdata->etr_buf))
+                return -EBUSY;
+
+        /* Set the buffer for the session */
+        drvdata->etr_buf = etr_buf;
+        /*
+         * If this ETR is connected to a CATU, enable it before we turn
+         * this on.
+         */
+        tmc_etr_enable_catu(drvdata);
+
+        __tmc_etr_enable_hw(drvdata);
+        return 0;
+}
+
 /*
  * Return the available trace data in the buffer (starts at etr_buf->offset,
  * limited by etr_buf->len) from @pos, with a maximum limit of @len,
@@ -1037,7 +1049,7 @@ static void tmc_etr_sync_sysfs_buf(struct tmc_drvdata *drvdata)
         }
 }
 
-static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
+static void __tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
 {
         CS_UNLOCK(drvdata->base);
 
@@ -1053,6 +1065,11 @@ static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
 
         CS_LOCK(drvdata->base);
 
+}
+
+static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
+{
+        __tmc_etr_disable_hw(drvdata);
         /* Disable CATU device if this ETR is connected to one */
         tmc_etr_disable_catu(drvdata);
         /* Reset the ETR buf used by hardware */
@@ -1111,8 +1128,9 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
                 drvdata->sysfs_buf = new_buf;
         }
 
-        drvdata->mode = CS_MODE_SYSFS;
-        tmc_etr_enable_hw(drvdata, drvdata->sysfs_buf);
+        ret = tmc_etr_enable_hw(drvdata, drvdata->sysfs_buf);
+        if (!ret)
+                drvdata->mode = CS_MODE_SYSFS;
 out:
         spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
@@ -1342,8 +1360,9 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
 
         etr_perf->head = PERF_IDX2OFF(handle->head, etr_perf);
         drvdata->perf_data = etr_perf;
-        drvdata->mode = CS_MODE_PERF;
-        tmc_etr_enable_hw(drvdata, etr_perf->etr_buf);
+        rc = tmc_etr_enable_hw(drvdata, etr_perf->etr_buf);
+        if (!rc)
+                drvdata->mode = CS_MODE_PERF;
 
 unlock_out:
         spin_unlock_irqrestore(&drvdata->spinlock, flags);
@@ -1425,7 +1444,7 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
 
         /* Disable the TMC if we are trying to read from a running session. */
         if (drvdata->mode == CS_MODE_SYSFS)
-                tmc_etr_disable_hw(drvdata);
+                __tmc_etr_disable_hw(drvdata);
 
         drvdata->reading = true;
 out:
@@ -1452,7 +1471,7 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
                  * buffer. Since the tracer is still enabled drvdata::buf can't
                  * be NULL.
                  */
-                tmc_etr_enable_hw(drvdata, drvdata->sysfs_buf);
+                __tmc_etr_enable_hw(drvdata);
         } else {
                 /*
                  * The ETR is not tracing and the buffer was just read.