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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>
This commit is contained in:
Alexander Shishkin 2019-05-03 11:44:50 +03:00 committed by Greg Kroah-Hartman
parent 4840572d3d
commit 6cac7866c2
2 changed files with 36 additions and 0 deletions
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8
Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc
View File

@ -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".

28
drivers/hwtracing/intel_th/msu.c
View File

@ -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,
};