mei: expose device state in sysfs

Expose mei device state to user-space through sysfs.
This gives indication to applications that driver is in transition,
usefully mostly to detect link reset state.

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 59 insertions, 6 deletions

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index b454df214dde..ad02097d7fee 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -28,6 +28,12 @@
 #include "mei_dev.h"
 #include "client.h"
 
+static struct class *mei_class;
+static dev_t mei_devt;
+#define MEI_MAX_DEVS  MINORMASK
+static DEFINE_MUTEX(mei_minor_lock);
+static DEFINE_IDR(mei_idr);
+
 /**
  * mei_open - the open function
  *
@@ -829,12 +835,65 @@ static ssize_t fw_ver_show(struct device *device,
 }
 static DEVICE_ATTR_RO(fw_ver);
 
+/**
+ * dev_state_show - display device state
+ *
+ * @device: device pointer
+ * @attr: attribute pointer
+ * @buf:  char out buffer
+ *
+ * Return: number of the bytes printed into buf or error
+ */
+static ssize_t dev_state_show(struct device *device,
+			      struct device_attribute *attr, char *buf)
+{
+	struct mei_device *dev = dev_get_drvdata(device);
+	enum mei_dev_state dev_state;
+
+	mutex_lock(&dev->device_lock);
+	dev_state = dev->dev_state;
+	mutex_unlock(&dev->device_lock);
+
+	return sprintf(buf, "%s", mei_dev_state_str(dev_state));
+}
+static DEVICE_ATTR_RO(dev_state);
+
+static int match_devt(struct device *dev, const void *data)
+{
+	const dev_t *devt = data;
+
+	return dev->devt == *devt;
+}
+
+/**
+ * dev_set_devstate: set to new device state and notify sysfs file.
+ *
+ * @dev: mei_device
+ * @state: new device state
+ */
+void mei_set_devstate(struct mei_device *dev, enum mei_dev_state state)
+{
+	struct device *clsdev;
+
+	if (dev->dev_state == state)
+		return;
+
+	dev->dev_state = state;
+
+	clsdev = class_find_device(mei_class, NULL, &dev->cdev.dev, match_devt);
+	if (clsdev) {
+		sysfs_notify(&clsdev->kobj, NULL, "dev_state");
+		put_device(clsdev);
+	}
+}
+
 static struct attribute *mei_attrs[] = {
 	&dev_attr_fw_status.attr,
 	&dev_attr_hbm_ver.attr,
 	&dev_attr_hbm_ver_drv.attr,
 	&dev_attr_tx_queue_limit.attr,
 	&dev_attr_fw_ver.attr,
+	&dev_attr_dev_state.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(mei);
@@ -858,12 +917,6 @@ static const struct file_operations mei_fops = {
 	.llseek = no_llseek
 };
 
-static struct class *mei_class;
-static dev_t mei_devt;
-#define MEI_MAX_DEVS  MINORMASK
-static DEFINE_MUTEX(mei_minor_lock);
-static DEFINE_IDR(mei_idr);
-
 /**
  * mei_minor_get - obtain next free device minor number
  *