[PATCH v3 3/4] bus: fsl-mc: add root dprc rescan attribute

[Ioana Ciornei <ioana.ciornei@nxp.com>]

Introduce the rescan attribute as a device attribute to
synchronize the fsl-mc bus objects and the MC firmware.

To rescan the root dprc only, e.g.
echo 1 > /sys/bus/fsl-mc/devices/dprc.1/rescan

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
---
Changes in v2:
   - remove the rescan dev_attr on the remove path
Changes in v3:
   - none

 Documentation/ABI/stable/sysfs-bus-fsl-mc |  9 ++++++++
 MAINTAINERS                               |  1 +
 drivers/bus/fsl-mc/dprc-driver.c          | 36 +++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+)
 create mode 100644 Documentation/ABI/stable/sysfs-bus-fsl-mc

diff --git a/Documentation/ABI/stable/sysfs-bus-fsl-mc b/Documentation/ABI/stable/sysfs-bus-fsl-mc
new file mode 100644
index 0000000..9f3a95e
--- /dev/null
+++ b/Documentation/ABI/stable/sysfs-bus-fsl-mc
@@ -0,0 +1,9 @@
+What:		/sys/bus/fsl-mc/devices/dprc.*/rescan
+Date:		November 2018
+KernelVersion:	5.0
+Contact:	Ioana Ciornei <ioana.ciornei@nxp.com>
+Description:	Writing a non-zero value to this attribute will
+		force a rescan of dprc.X container in the system and
+		synchronize the objects under dprc.X and the
+		Management Complex firmware.
+Users:		Userspace drivers and management tools
diff --git a/MAINTAINERS b/MAINTAINERS
index e841cc4..7b76a80 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12283,6 +12283,7 @@ F:	drivers/bus/fsl-mc/
 F:	Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt
 F:	Documentation/networking/dpaa2/overview.rst
 F:	include/uapi/linux/fsl_mc.h
+F:	Documentation/ABI/stable/sysfs-bus-fsl-mc
 
 QT1010 MEDIA DRIVER
 M:	Antti Palosaari <crope@iki.fi>
diff --git a/drivers/bus/fsl-mc/dprc-driver.c b/drivers/bus/fsl-mc/dprc-driver.c
index bab0d5a..2f94aba 100644
--- a/drivers/bus/fsl-mc/dprc-driver.c
+++ b/drivers/bus/fsl-mc/dprc-driver.c
@@ -354,6 +354,33 @@ static int dprc_scan_container(struct fsl_mc_device *mc_bus_dev)
 	return 0;
 }
 
+static ssize_t rescan_store(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct fsl_mc_device *root_mc_dev;
+	struct fsl_mc_bus *root_mc_bus;
+	unsigned long val;
+
+	if (!fsl_mc_is_root_dprc(dev))
+		return -EINVAL;
+
+	root_mc_dev = to_fsl_mc_device(dev);
+	root_mc_bus = to_fsl_mc_bus(root_mc_dev);
+
+	if (kstrtoul(buf, 0, &val) < 0)
+		return -EINVAL;
+
+	if (val) {
+		mutex_lock(&root_mc_bus->scan_mutex);
+		dprc_scan_objects(root_mc_dev, NULL);
+		mutex_unlock(&root_mc_bus->scan_mutex);
+	}
+
+	return count;
+}
+static DEVICE_ATTR_WO(rescan);
+
 /**
  * dprc_irq0_handler - Regular ISR for DPRC interrupt 0
  *
@@ -692,6 +719,13 @@ static int dprc_probe(struct fsl_mc_device *mc_dev)
 
 	mutex_init(&mc_bus->scan_mutex);
 
+	error = device_create_file(&mc_dev->dev, &dev_attr_rescan);
+	if (error < 0) {
+		dev_err(&mc_dev->dev, "device_create_file() failed: %d\n",
+			error);
+		goto error_cleanup_open;
+	}
+
 	/*
 	 * Discover MC objects in DPRC object:
 	 */
@@ -788,6 +822,8 @@ static int dprc_remove(struct fsl_mc_device *mc_dev)
 		fsl_mc_uapi_remove_device_file(mc_bus);
 	}
 
+	device_remove_file(&mc_dev->dev, &dev_attr_rescan);
+
 	dev_info(&mc_dev->dev, "DPRC device unbound from driver");
 	return 0;
 }
-- 
1.9.1