2 files changed, 36 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc b/Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc
index b940c5d91cf7..f54ae244f3f1 100644
--- a/Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc
+++ b/Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc
@@ -30,4 +30,12 @@ Description:	(RW) Configure MSC buffer size for "single" or "multi" modes.
                 there are no active users and tracing is not enabled) and then
                 allocates a new one.
 
+What:           /sys/bus/intel_th/devices/<intel_th_id>-msc<msc-id>/win_switch
+Date:           May 2019
+KernelVersion:  5.2
+Contact:        Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:    (RW) Trigger window switch for the MSC's buffer, in
+                multi-window mode. In "multi" mode, accepts writes of "1", thereby
+                triggering a window switch for the buffer. Returns an error in any
+                other operating mode or attempts to write something other than "1".
 
diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
index b0bb69942328..aed72b33675d 100644
--- a/drivers/hwtracing/intel_th/msu.c
+++ b/drivers/hwtracing/intel_th/msu.c
@@ -1572,10 +1572,38 @@ free_win:
 
 static DEVICE_ATTR_RW(nr_pages);
 
+static ssize_t
+win_switch_store(struct device *dev, struct device_attribute *attr,
+                 const char *buf, size_t size)
+{
+        struct msc *msc = dev_get_drvdata(dev);
+        unsigned long val;
+        int ret;
+
+        ret = kstrtoul(buf, 10, &val);
+        if (ret)
+                return ret;
+
+        if (val != 1)
+                return -EINVAL;
+
+        mutex_lock(&msc->buf_mutex);
+        if (msc->mode != MSC_MODE_MULTI)
+                ret = -ENOTSUPP;
+        else
+                ret = intel_th_trace_switch(msc->thdev);
+        mutex_unlock(&msc->buf_mutex);
+
+        return ret ? ret : size;
+}
+
+static DEVICE_ATTR_WO(win_switch);
+
 static struct attribute *msc_output_attrs[] = {
         &dev_attr_wrap.attr,
         &dev_attr_mode.attr,
         &dev_attr_nr_pages.attr,
+        &dev_attr_win_switch.attr,
         NULL,
 };