intel_th: msu: Add a sysfs attribute to trigger window switch

Now that we have the means to trigger a window switch for the MSU trace
store, add a sysfs file to allow triggering it from userspace.

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

diff --git a/Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc b/Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc
index b940c5d91cf7a37e32cbf92690cf830712c671de..f54ae244f3f1716d8f997dc124b3edbf2bb52069 100644 (file)
--- 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 b0bb6994232857baf1d924bec75422d462ebcdd3..aed72b33675de877363b91919b4cedd4efb0b262 100644 (file)
--- 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,
 };