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

[Ioana Ciornei]

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

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

Signed-off-by: Ioana Ciornei <ioana.ciornei@xxxxxxx>
---
Changes in v2:
  - added proper documentation in /Documentation/ABI/
  - updated the MAINTAINERS file
Changes in v3:
  - no change

 Documentation/ABI/stable/sysfs-bus-fsl-mc |  7 +++++
 drivers/bus/fsl-mc/fsl-mc-bus.c           | 48 +++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/Documentation/ABI/stable/sysfs-bus-fsl-mc b/Documentation/ABI/stable/sysfs-bus-fsl-mc
index e530e8c..0663fbd 100644
--- a/Documentation/ABI/stable/sysfs-bus-fsl-mc
+++ b/Documentation/ABI/stable/sysfs-bus-fsl-mc
@@ -4,3 +4,10 @@ KernelVersion:	4.16
 Contact:	Ioana Ciornei <ioana.ciornei@xxxxxxx>
 Description:	Root dprc rescan attribute
 Users:		Userspace drivers and management tools
+
+What:		/sys/bus/fsl-mc/rescan
+Date:		March. 2018
+KernelVersion:	4.16
+Contact:	Ioana Ciornei <ioana.ciornei@xxxxxxx>
+Description:	Bus rescan attribute
+Users:		Userspace drivers and management tools
diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
index 9d02984..80010d1 100644
--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -172,11 +172,59 @@ static ssize_t rescan_store(struct device *dev,
 
 ATTRIBUTE_GROUPS(fsl_mc_dev);
 
+static int scan_fsl_mc_bus(struct device *dev, void *data)
+{
+	struct fsl_mc_device *root_mc_dev;
+	struct fsl_mc_bus *root_mc_bus;
+
+	if (!fsl_mc_is_root_dprc(dev))
+		goto exit;
+
+	root_mc_dev = to_fsl_mc_device(dev);
+	root_mc_bus = to_fsl_mc_bus(root_mc_dev);
+	mutex_lock(&root_mc_bus->scan_mutex);
+	dprc_scan_objects(root_mc_dev, NULL);
+	mutex_unlock(&root_mc_bus->scan_mutex);
+
+exit:
+	return 0;
+}
+
+static ssize_t bus_rescan_store(struct bus_type *bus,
+				const char *buf, size_t count)
+{
+	unsigned long val;
+
+	if (kstrtoul(buf, 0, &val) < 0)
+		return -EINVAL;
+
+	if (val)
+		bus_for_each_dev(bus, NULL, NULL, scan_fsl_mc_bus);
+
+	return count;
+}
+static BUS_ATTR(rescan, 0220, NULL, bus_rescan_store);
+
+static struct attribute *fsl_mc_bus_attrs[] = {
+	&bus_attr_rescan.attr,
+	NULL,
+};
+
+static const struct attribute_group fsl_mc_bus_group = {
+	.attrs = fsl_mc_bus_attrs,
+};
+
+static const struct attribute_group *fsl_mc_bus_groups[] = {
+	&fsl_mc_bus_group,
+	NULL,
+};
+
 struct bus_type fsl_mc_bus_type = {
 	.name = "fsl-mc",
 	.match = fsl_mc_bus_match,
 	.uevent = fsl_mc_bus_uevent,
 	.dev_groups = fsl_mc_dev_groups,
+	.bus_groups = fsl_mc_bus_groups,
 };
 EXPORT_SYMBOL_GPL(fsl_mc_bus_type);
 
-- 
1.9.1