bus: fsl-mc: add bus rescan attribute

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@nxp.com>

Documentation/ABI/stable/sysfs-bus-fsl-mc

@@ -7,3 +7,13 @@ Description:	Writing a non-zero value to this attribute will
 		synchronize the objects under dprc.X and the
 		Management Complex firmware.
 Users:		Userspace drivers and management tools
+
+What:		/sys/bus/fsl-mc/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 fsl-mc bus in the system and
+		synchronize the objects under fsl-mc bus and the
+		Management Complex firmware.
+Users:		Userspace drivers and management tools

drivers/bus/fsl-mc/dprc-driver.c

@@ -214,8 +214,8 @@ static void dprc_add_new_devices(struct fsl_mc_device *mc_bus_dev,
  * populated before they can get allocation requests from probe callbacks
  * of the device drivers for the non-allocatable devices.
  */
-static int dprc_scan_objects(struct fsl_mc_device *mc_bus_dev,
-			     unsigned int *total_irq_count)
+int dprc_scan_objects(struct fsl_mc_device *mc_bus_dev,
+		      unsigned int *total_irq_count)
 {
 	int num_child_objects;
 	int dprc_get_obj_failures;

drivers/bus/fsl-mc/fsl-mc-bus.c

@@ -154,12 +154,53 @@ static struct attribute *fsl_mc_dev_attrs[] = {
 
 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 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_WO(rescan);
+
+static struct attribute *fsl_mc_bus_attrs[] = {
+	&bus_attr_rescan.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(fsl_mc_bus);
+
 struct bus_type fsl_mc_bus_type = {
 	.name = "fsl-mc",
 	.match = fsl_mc_bus_match,
 	.uevent = fsl_mc_bus_uevent,
 	.dma_configure  = fsl_mc_dma_configure,
 	.dev_groups = fsl_mc_dev_groups,
+	.bus_groups = fsl_mc_bus_groups,
 };
 EXPORT_SYMBOL_GPL(fsl_mc_bus_type);
 

drivers/bus/fsl-mc/fsl-mc-private.h

@@ -556,6 +556,8 @@ int __init dprc_driver_init(void);
 
 void dprc_driver_exit(void);
 
+int dprc_scan_objects(struct fsl_mc_device *mc_bus_dev,
+		      unsigned int *total_irq_count);
 int __init fsl_mc_allocator_driver_init(void);
 
 void fsl_mc_allocator_driver_exit(void);