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Subject[GIT PULL 05/16] stm class: Add a helper for writing data packets
Date
Add a helper to write a sequence of bytes as STP data packets. This
is used by protocol drivers to output their metadata, as well as the
actual data payload.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
drivers/hwtracing/stm/core.c | 51 +++++++++++++++++++++++++++---------
drivers/hwtracing/stm/stm.h | 3 +++
2 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 915af2541dcd..b789a5f0688e 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -569,27 +569,52 @@ stm_assign_first_policy(struct stm_device *stm, struct stm_output *output,
return err;
}

-static ssize_t notrace stm_write(struct stm_data *data, unsigned int master,
- unsigned int channel, const char *buf, size_t count)
+/**
+ * stm_data_write() - send the given payload as data packets
+ * @data: stm driver's data
+ * @m: STP master
+ * @c: STP channel
+ * @ts_first: timestamp the first packet
+ * @buf: data payload buffer
+ * @count: data payload size
+ */
+ssize_t notrace stm_data_write(struct stm_data *data, unsigned int m,
+ unsigned int c, bool ts_first, const void *buf,
+ size_t count)
{
- unsigned int flags = STP_PACKET_TIMESTAMPED;
- const unsigned char *p = buf, nil = 0;
- size_t pos;
+ unsigned int flags = ts_first ? STP_PACKET_TIMESTAMPED : 0;
ssize_t sz;
+ size_t pos;

- for (pos = 0, p = buf; count > pos; pos += sz, p += sz) {
+ for (pos = 0, sz = 0; pos < count; pos += sz) {
sz = min_t(unsigned int, count - pos, 8);
- sz = data->packet(data, master, channel, STP_PACKET_DATA, flags,
- sz, p);
- flags = 0;
-
- if (sz < 0)
+ sz = data->packet(data, m, c, STP_PACKET_DATA, flags, sz,
+ &((u8 *)buf)[pos]);
+ if (sz <= 0)
break;
+
+ if (ts_first) {
+ flags = 0;
+ ts_first = false;
+ }
}

- data->packet(data, master, channel, STP_PACKET_FLAG, 0, 0, &nil);
+ return sz < 0 ? sz : pos;
+}
+EXPORT_SYMBOL_GPL(stm_data_write);
+
+static ssize_t notrace stm_write(struct stm_data *data, unsigned int master,
+ unsigned int channel, const char *buf, size_t count)
+{
+ const unsigned char nil = 0;
+ ssize_t sz;
+
+ sz = stm_data_write(data, master, channel, true, buf, count);
+ if (sz > 0)
+ data->packet(data, master, channel, STP_PACKET_FLAG, 0, 0,
+ &nil);

- return pos;
+ return sz;
}

static ssize_t stm_char_write(struct file *file, const char __user *buf,
diff --git a/drivers/hwtracing/stm/stm.h b/drivers/hwtracing/stm/stm.h
index ed7f3d07fa47..3569439d53bb 100644
--- a/drivers/hwtracing/stm/stm.h
+++ b/drivers/hwtracing/stm/stm.h
@@ -110,5 +110,8 @@ int stm_lookup_protocol(const char *name,
const struct stm_protocol_driver **pdrv,
const struct config_item_type **type);
void stm_put_protocol(const struct stm_protocol_driver *pdrv);
+ssize_t stm_data_write(struct stm_data *data, unsigned int m,
+ unsigned int c, bool ts_first, const void *buf,
+ size_t count);

#endif /* _STM_STM_H_ */
--
2.19.0
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