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Subject[GIT PULL 09/16] stm class: p_sys-t: Add support for CLOCKSYNC packets
Date
This adds support for CLOCKSYNC SyS-T packets, that establish correlation
between the transport clock (STP timestamps) and SyS-T timestamps. These
packets are sent periodically to allow the decoder to keep both time
sources in sync.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
drivers/hwtracing/stm/p_sys-t.c | 80 +++++++++++++++++++++++++++++++++
1 file changed, 80 insertions(+)

diff --git a/drivers/hwtracing/stm/p_sys-t.c b/drivers/hwtracing/stm/p_sys-t.c
index ffeb057b777c..b178a5495b67 100644
--- a/drivers/hwtracing/stm/p_sys-t.c
+++ b/drivers/hwtracing/stm/p_sys-t.c
@@ -72,15 +72,20 @@ enum sys_t_message_string_subtype {
MIPI_SYST_SEVERITY(INFO) | \
MIPI_SYST_OPT_GUID)

+#define CLOCK_SYNC_HEADER (MIPI_SYST_TYPES(CLOCK, TRANSPORT_SYNC) | \
+ MIPI_SYST_SEVERITY(MAX))
+
struct sys_t_policy_node {
uuid_t uuid;
bool do_len;
unsigned long ts_interval;
+ unsigned long clocksync_interval;
};

struct sys_t_output {
struct sys_t_policy_node node;
unsigned long ts_jiffies;
+ unsigned long clocksync_jiffies;
};

static void sys_t_policy_node_init(void *priv)
@@ -191,10 +196,42 @@ sys_t_policy_ts_interval_store(struct config_item *item, const char *page,

CONFIGFS_ATTR(sys_t_policy_, ts_interval);

+static ssize_t sys_t_policy_clocksync_interval_show(struct config_item *item,
+ char *page)
+{
+ struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
+
+ return sprintf(page, "%u\n", jiffies_to_msecs(pn->clocksync_interval));
+}
+
+static ssize_t
+sys_t_policy_clocksync_interval_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct mutex *mutexp = &item->ci_group->cg_subsys->su_mutex;
+ struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
+ unsigned int ms;
+ int ret;
+
+ mutex_lock(mutexp);
+ ret = kstrtouint(page, 10, &ms);
+ mutex_unlock(mutexp);
+
+ if (!ret) {
+ pn->clocksync_interval = msecs_to_jiffies(ms);
+ return count;
+ }
+
+ return ret;
+}
+
+CONFIGFS_ATTR(sys_t_policy_, clocksync_interval);
+
static struct configfs_attribute *sys_t_policy_attrs[] = {
&sys_t_policy_attr_uuid,
&sys_t_policy_attr_do_len,
&sys_t_policy_attr_ts_interval,
+ &sys_t_policy_attr_clocksync_interval,
NULL,
};

@@ -210,6 +247,43 @@ static inline bool sys_t_need_ts(struct sys_t_output *op)
return false;
}

+static bool sys_t_need_clock_sync(struct sys_t_output *op)
+{
+ if (op->node.clocksync_interval &&
+ time_after(op->clocksync_jiffies + op->node.clocksync_interval,
+ jiffies)) {
+ op->clocksync_jiffies = jiffies;
+
+ return true;
+ }
+
+ return false;
+}
+
+static ssize_t
+sys_t_clock_sync(struct stm_data *data, unsigned int m, unsigned int c)
+{
+ u32 header = CLOCK_SYNC_HEADER;
+ const unsigned char nil = 0;
+ u64 payload[2]; /* Clock value and frequency */
+ ssize_t sz;
+
+ sz = data->packet(data, m, c, STP_PACKET_DATA, STP_PACKET_TIMESTAMPED,
+ 4, (u8 *)&header);
+ if (sz <= 0)
+ return sz;
+
+ payload[0] = ktime_get_real_ns();
+ payload[1] = NSEC_PER_SEC;
+ sz = stm_data_write(data, m, c, false, &payload, sizeof(payload));
+ if (sz <= 0)
+ return sz;
+
+ data->packet(data, m, c, STP_PACKET_FLAG, 0, 0, &nil);
+
+ return sizeof(header) + sizeof(payload);
+}
+
static ssize_t sys_t_write(struct stm_data *data, struct stm_output *output,
unsigned int chan, const char *buf, size_t count)
{
@@ -224,6 +298,12 @@ static ssize_t sys_t_write(struct stm_data *data, struct stm_output *output,
if (!op)
return -EINVAL;

+ if (sys_t_need_clock_sync(op)) {
+ sz = sys_t_clock_sync(data, m, c);
+ if (sz <= 0)
+ return sz;
+ }
+
if (op->node.do_len)
header |= MIPI_SYST_OPT_LEN;
if (sys_t_need_ts(op))
--
2.19.0
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