in coresight/coresight-etb10.c [427:572]
static unsigned long etb_update_buffer(struct coresight_device *csdev,
struct perf_output_handle *handle,
void *sink_config)
{
bool lost = false;
int i, cur;
u8 *buf_ptr;
const u32 *barrier;
u32 read_ptr, write_ptr, capacity;
u32 status, read_data;
unsigned long offset, to_read = 0, flags;
struct cs_buffers *buf = sink_config;
struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
if (!buf)
return 0;
capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS;
spin_lock_irqsave(&drvdata->spinlock, flags);
/* Don't do anything if another tracer is using this sink */
if (atomic_read(csdev->refcnt) != 1)
goto out;
__etb_disable_hw(drvdata);
CS_UNLOCK(drvdata->base);
/* unit is in words, not bytes */
read_ptr = readl_relaxed(drvdata->base + ETB_RAM_READ_POINTER);
write_ptr = readl_relaxed(drvdata->base + ETB_RAM_WRITE_POINTER);
/*
* Entries should be aligned to the frame size. If they are not
* go back to the last alignment point to give decoding tools a
* chance to fix things.
*/
if (write_ptr % ETB_FRAME_SIZE_WORDS) {
dev_err(&csdev->dev,
"write_ptr: %lu not aligned to formatter frame size\n",
(unsigned long)write_ptr);
write_ptr &= ~(ETB_FRAME_SIZE_WORDS - 1);
lost = true;
}
/*
* Get a hold of the status register and see if a wrap around
* has occurred. If so adjust things accordingly. Otherwise
* start at the beginning and go until the write pointer has
* been reached.
*/
status = readl_relaxed(drvdata->base + ETB_STATUS_REG);
if (status & ETB_STATUS_RAM_FULL) {
lost = true;
to_read = capacity;
read_ptr = write_ptr;
} else {
to_read = CIRC_CNT(write_ptr, read_ptr, drvdata->buffer_depth);
to_read *= ETB_FRAME_SIZE_WORDS;
}
/*
* Make sure we don't overwrite data that hasn't been consumed yet.
* It is entirely possible that the HW buffer has more data than the
* ring buffer can currently handle. If so adjust the start address
* to take only the last traces.
*
* In snapshot mode we are looking to get the latest traces only and as
* such, we don't care about not overwriting data that hasn't been
* processed by user space.
*/
if (!buf->snapshot && to_read > handle->size) {
u32 mask = ~(ETB_FRAME_SIZE_WORDS - 1);
/* The new read pointer must be frame size aligned */
to_read = handle->size & mask;
/*
* Move the RAM read pointer up, keeping in mind that
* everything is in frame size units.
*/
read_ptr = (write_ptr + drvdata->buffer_depth) -
to_read / ETB_FRAME_SIZE_WORDS;
/* Wrap around if need be*/
if (read_ptr > (drvdata->buffer_depth - 1))
read_ptr -= drvdata->buffer_depth;
/* let the decoder know we've skipped ahead */
lost = true;
}
/*
* Don't set the TRUNCATED flag in snapshot mode because 1) the
* captured buffer is expected to be truncated and 2) a full buffer
* prevents the event from being re-enabled by the perf core,
* resulting in stale data being send to user space.
*/
if (!buf->snapshot && lost)
perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
/* finally tell HW where we want to start reading from */
writel_relaxed(read_ptr, drvdata->base + ETB_RAM_READ_POINTER);
cur = buf->cur;
offset = buf->offset;
barrier = coresight_barrier_pkt;
for (i = 0; i < to_read; i += 4) {
buf_ptr = buf->data_pages[cur] + offset;
read_data = readl_relaxed(drvdata->base +
ETB_RAM_READ_DATA_REG);
if (lost && i < CORESIGHT_BARRIER_PKT_SIZE) {
read_data = *barrier;
barrier++;
}
*(u32 *)buf_ptr = read_data;
buf_ptr += 4;
offset += 4;
if (offset >= PAGE_SIZE) {
offset = 0;
cur++;
/* wrap around at the end of the buffer */
cur &= buf->nr_pages - 1;
}
}
/* reset ETB buffer for next run */
writel_relaxed(0x0, drvdata->base + ETB_RAM_READ_POINTER);
writel_relaxed(0x0, drvdata->base + ETB_RAM_WRITE_POINTER);
/*
* In snapshot mode we simply increment the head by the number of byte
* that were written. User space will figure out how many bytes to get
* from the AUX buffer based on the position of the head.
*/
if (buf->snapshot)
handle->head += to_read;
__etb_enable_hw(drvdata);
CS_LOCK(drvdata->base);
out:
spin_unlock_irqrestore(&drvdata->spinlock, flags);
return to_read;
}