From 6cac7866c27418cd784fbb8041c2dddd6d966bc7 Mon Sep 17 00:00:00 2001
From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Date: Fri, 3 May 2019 11:44:50 +0300
Subject: [PATCH] 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>
---
.../testing/sysfs-bus-intel_th-devices-msc | 8 ++++++
drivers/hwtracing/intel_th/msu.c | 28 +++++++++++++++++++
2 files changed, 36 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc b/Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc
index b940c5d91cf7a3..f54ae244f3f171 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 b0bb6994232857..aed72b33675de8 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,
};
--
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