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Message-Id: <1498844519-8845-4-git-send-email-mathieu.poirier@linaro.org>
Date: Fri, 30 Jun 2017 11:41:57 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 3/5] coresight: Add barrier packet for synchronisation
When a buffer overflow happens the synchronisation patckets usually
present at the beginning of the buffer are lost, a situation that
prevents the decoder from knowing the context of the traces being
decoded.
This patch adds a barrier packet to be used by sink IPs when a buffer
overflow condition is detected. These barrier packets are then used
by the decoding library as markers to force re-synchronisation.
Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
---
drivers/hwtracing/coresight/coresight-etb10.c | 22 +++++++++++++++++++--
drivers/hwtracing/coresight/coresight-priv.h | 2 ++
drivers/hwtracing/coresight/coresight-tmc-etf.c | 26 ++++++++++++++++++++++++-
drivers/hwtracing/coresight/coresight-tmc-etr.c | 12 ++++++++++++
drivers/hwtracing/coresight/coresight.c | 8 ++++++++
5 files changed, 67 insertions(+), 3 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index 50f4846e6271..42360306f049 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -200,8 +200,10 @@ static void etb_disable_hw(struct etb_drvdata *drvdata)
static void etb_dump_hw(struct etb_drvdata *drvdata)
{
+ bool lost = false;
int i;
u8 *buf_ptr;
+ const u32 *barrier;
u32 read_data, depth;
u32 read_ptr, write_ptr;
u32 frame_off, frame_endoff;
@@ -223,16 +225,24 @@ static void etb_dump_hw(struct etb_drvdata *drvdata)
}
if ((readl_relaxed(drvdata->base + ETB_STATUS_REG)
- & ETB_STATUS_RAM_FULL) == 0)
+ & ETB_STATUS_RAM_FULL) == 0) {
writel_relaxed(0x0, drvdata->base + ETB_RAM_READ_POINTER);
- else
+ } else {
writel_relaxed(write_ptr, drvdata->base + ETB_RAM_READ_POINTER);
+ lost = true;
+ }
depth = drvdata->buffer_depth;
buf_ptr = drvdata->buf;
+ barrier = barrier_pkt;
for (i = 0; i < depth; i++) {
read_data = readl_relaxed(drvdata->base +
ETB_RAM_READ_DATA_REG);
+ if (lost && *barrier) {
+ read_data = *barrier;
+ barrier++;
+ }
+
*(u32 *)buf_ptr = read_data;
buf_ptr += 4;
}
@@ -354,6 +364,7 @@ static void etb_update_buffer(struct coresight_device *csdev,
bool lost = false;
int i, cur;
u8 *buf_ptr;
+ const u32 *barrier;
u32 read_ptr, write_ptr, capacity;
u32 status, read_data, to_read;
unsigned long offset;
@@ -438,10 +449,17 @@ static void etb_update_buffer(struct coresight_device *csdev,
cur = buf->cur;
offset = buf->offset;
+ barrier = 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 && *barrier) {
+ read_data = *barrier;
+ barrier++;
+ }
+
*(u32 *)buf_ptr = read_data;
buf_ptr += 4;
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index 5f662d82052c..3e25b1dd1a1a 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -56,6 +56,8 @@ static ssize_t name##_show(struct device *_dev, \
} \
static DEVICE_ATTR_RO(name)
+extern const u32 barrier_pkt[5];
+
enum etm_addr_type {
ETM_ADDR_TYPE_NONE,
ETM_ADDR_TYPE_SINGLE,
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 2e0fb5b9372c..d189b28bd5c4 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -43,17 +43,34 @@ static void tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata)
{
+ bool lost = false;
char *bufp;
- u32 read_data;
+ const u32 *barrier;
+ u32 read_data, status;
int i;
+ /*
+ * Get a hold of the status register and see if a wrap around
+ * has occurred.
+ */
+ status = readl_relaxed(drvdata->base + TMC_STS);
+ if (status & TMC_STS_FULL)
+ lost = true;
+
bufp = drvdata->buf;
drvdata->len = 0;
+ barrier = barrier_pkt;
while (1) {
for (i = 0; i < drvdata->memwidth; i++) {
read_data = readl_relaxed(drvdata->base + TMC_RRD);
if (read_data == 0xFFFFFFFF)
return;
+
+ if (lost && *barrier) {
+ read_data = *barrier;
+ barrier++;
+ }
+
memcpy(bufp, &read_data, 4);
bufp += 4;
drvdata->len += 4;
@@ -371,6 +388,7 @@ static void tmc_update_etf_buffer(struct coresight_device *csdev,
{
bool lost = false;
int i, cur;
+ const u32 *barrier;
u32 *buf_ptr;
u32 read_ptr, write_ptr;
u32 status, to_read;
@@ -451,12 +469,18 @@ static void tmc_update_etf_buffer(struct coresight_device *csdev,
cur = buf->cur;
offset = buf->offset;
+ barrier = barrier_pkt;
/* for every byte to read */
for (i = 0; i < to_read; i += 4) {
buf_ptr = buf->data_pages[cur] + offset;
*buf_ptr = readl_relaxed(drvdata->base + TMC_RRD);
+ if (lost && *barrier) {
+ *buf_ptr = *barrier;
+ barrier++;
+ }
+
offset += 4;
if (offset >= PAGE_SIZE) {
offset = 0;
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 5d312699b3b9..b8fb981de7b6 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -59,6 +59,8 @@ static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
static void tmc_etr_dump_hw(struct tmc_drvdata *drvdata)
{
+ const u32 *barrier;
+ u32 *temp;
u32 rwp, val;
rwp = readl_relaxed(drvdata->base + TMC_RWP);
@@ -71,6 +73,16 @@ static void tmc_etr_dump_hw(struct tmc_drvdata *drvdata)
if (val & TMC_STS_FULL) {
drvdata->buf = drvdata->vaddr + rwp - drvdata->paddr;
drvdata->len = drvdata->size;
+
+ barrier = barrier_pkt;
+ temp = (u32 *)drvdata->buf;
+
+ while (*barrier) {
+ *temp = *barrier;
+ temp++;
+ barrier++;
+ }
+
} else {
drvdata->buf = drvdata->vaddr;
drvdata->len = rwp - drvdata->paddr;
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index 6a0202b7384f..b8091bef21dc 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -53,6 +53,14 @@ static DEFINE_PER_CPU(struct list_head *, tracer_path);
*/
static struct list_head *stm_path;
+/*
+ * When losing synchronisation a new barrier packet needs to be inserted at the
+ * beginning of the data collected in a buffer. That way the decoder knows that
+ * it needs to look for another sync sequence.
+ */
+const u32 barrier_pkt[5] = {0x7fffffff, 0x7fffffff,
+ 0x7fffffff, 0x7fffffff, 0x0};
+
static int coresight_id_match(struct device *dev, void *data)
{
int trace_id, i_trace_id;
--
2.7.4
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