[PATCH 15/17] coresight: etr_buf: Add helper for padding an area of trace data

[Suzuki K Poulose]

This patch adds a helper to insert barrier packets for a given
size (aligned to packet size) at given offset in an etr_buf. This
will be used later for perf mode when we try to start in the
middle of an SG buffer.

Cc: Mathieu Poirier <mathieu.poir...@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
---
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 52 ++++++++++++++++++++++---
 1 file changed, 46 insertions(+), 6 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c 
b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index f8e654e1f5b2..229c36b7266c 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -999,18 +999,58 @@ static ssize_t tmc_etr_buf_get_data(struct etr_buf 
*etr_buf,
        return etr_buf->ops->get_data(etr_buf, (u64)offset, len, bufpp);
 }
 
+/*
+ * tmc_etr_buf_insert_barrier_packets : Insert barrier packets at @offset upto
+ * @size of bytes in the given buffer. @size should be aligned to the barrier
+ * packet size.
+ *
+ * Returns the new @offset after filling the barriers on success. Otherwise
+ * returns error.
+ */
 static inline s64
-tmc_etr_buf_insert_barrier_packet(struct etr_buf *etr_buf, u64 offset)
+tmc_etr_buf_insert_barrier_packets(struct etr_buf *etr_buf,
+                                  u64 offset, u64 size)
 {
        ssize_t len;
        char *bufp;
 
-       len = tmc_etr_buf_get_data(etr_buf, offset,
-                                  CORESIGHT_BARRIER_PKT_SIZE, &bufp);
-       if (WARN_ON(len <= CORESIGHT_BARRIER_PKT_SIZE))
+       if ((size % CORESIGHT_BARRIER_PKT_SIZE) ||
+           (offset % CORESIGHT_BARRIER_PKT_SIZE))
                return -EINVAL;
-       coresight_insert_barrier_packet(bufp);
-       return offset + CORESIGHT_BARRIER_PKT_SIZE;
+       do {
+               len = tmc_etr_buf_get_data(etr_buf, offset, size, &bufp);
+               if (WARN_ON(len <= 0))
+                       return -EINVAL;
+               /*
+                * We are guaranteed that @bufp will point to a linear range
+                * of @len bytes, where @len <= @size.
+                */
+               size -= len;
+               offset += len;
+               while (len >= CORESIGHT_BARRIER_PKT_SIZE) {
+                       coresight_insert_barrier_packet(bufp);
+                       bufp += CORESIGHT_BARRIER_PKT_SIZE;
+                       len -= CORESIGHT_BARRIER_PKT_SIZE;
+               }
+
+               /*
+                * Normally we shouldn't have any left over here, as the trace
+                * should always be aligned to ETR Frame size.
+                */
+               WARN_ON(len);
+               /* If we reached the end of the buffer, wrap around */
+               if (offset == etr_buf->size)
+                       offset -= etr_buf->size;
+       } while (size);
+
+       return offset;
+}
+
+static inline s64
+tmc_etr_buf_insert_barrier_packet(struct etr_buf *etr_buf, u64 offset)
+{
+       return tmc_etr_buf_insert_barrier_packets(etr_buf, offset,
+                                         CORESIGHT_BARRIER_PKT_SIZE);
 }
 
 /*
-- 
2.13.6