stm class: Support devices that override software assigned masters

Some STM devices adjust software assigned master numbers depending on
the trace source and its runtime state and whatnot. This patch adds
a sysfs attribute to inform the trace-side software that master numbers
assigned to software sources will not match those in the STP stream,
so that, for example, master/channel allocation policy can be adjusted
accordingly.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 2591442e2c5b..ff31108b066f 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -67,9 +67,24 @@ static ssize_t channels_show(struct device *dev,
 
 static DEVICE_ATTR_RO(channels);
 
+static ssize_t hw_override_show(struct device *dev,
+                                struct device_attribute *attr,
+                                char *buf)
+{
+        struct stm_device *stm = to_stm_device(dev);
+        int ret;
+
+        ret = sprintf(buf, "%u\n", stm->data->hw_override);
+
+        return ret;
+}
+
+static DEVICE_ATTR_RO(hw_override);
+
 static struct attribute *stm_attrs[] = {
         &dev_attr_masters.attr,
         &dev_attr_channels.attr,
+        &dev_attr_hw_override.attr,
         NULL,
 };