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stm class: Add a helper for writing data packets

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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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexander Shishkin 2018-10-05 15:42:55 +03:00 committed by Greg Kroah-Hartman
parent c7fd62bc69
commit d279a38020
2 changed files with 43 additions and 15 deletions
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55
drivers/hwtracing/stm/core.c
View File

@ -569,27 +569,52 @@ stm_assign_first_policy(struct stm_device *stm, struct stm_output *output,
return err;
}
/**
* 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 = ts_first ? STP_PACKET_TIMESTAMPED : 0;
ssize_t sz;
size_t pos;
for (pos = 0, sz = 0; pos < count; pos += sz) {
sz = min_t(unsigned int, count - pos, 8);
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;
}
}
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)
{
unsigned int flags = STP_PACKET_TIMESTAMPED;
const unsigned char *p = buf, nil = 0;
size_t pos;
const unsigned char nil = 0;
ssize_t sz;
for (pos = 0, p = buf; count > pos; pos += sz, p += sz) {
sz = min_t(unsigned int, count - pos, 8);
sz = data->packet(data, master, channel, STP_PACKET_DATA, flags,
sz, p);
flags = 0;
sz = stm_data_write(data, master, channel, true, buf, count);
if (sz > 0)
data->packet(data, master, channel, STP_PACKET_FLAG, 0, 0,
&nil);
if (sz < 0)
break;
}
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,

3
drivers/hwtracing/stm/stm.h
View File

@ -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_ */