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

[Ioana Ciornei]

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@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 |  6 ++++++
 MAINTAINERS                               |  1 +
 drivers/bus/fsl-mc/dprc-driver.c          |  4 ++--
 drivers/bus/fsl-mc/fsl-mc-bus.c           | 28 ++++++++++++++++++++++++++++
 drivers/bus/fsl-mc/fsl-mc-private.h       |  3 +++
 5 files changed, 40 insertions(+), 2 deletions(-)
 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..e530e8c
--- /dev/null
+++ b/Documentation/ABI/stable/sysfs-bus-fsl-mc
@@ -0,0 +1,6 @@
+What:		/sys/bus/fsl-mc/devices/dprc.*/rescan
+Date:		March. 2018
+KernelVersion:	4.16
+Contact:	Ioana Ciornei <ioana.ciornei@xxxxxxx>
+Description:	Root dprc rescan attribute
+Users:		Userspace drivers and management tools
diff --git a/MAINTAINERS b/MAINTAINERS
index 861cf1d..e179dc6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11486,6 +11486,7 @@ 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@xxxxxx>
diff --git a/drivers/bus/fsl-mc/dprc-driver.c b/drivers/bus/fsl-mc/dprc-driver.c
index 52c7e15..be80e3a 100644
--- a/drivers/bus/fsl-mc/dprc-driver.c
+++ b/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;
diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
index 0ade415..9d02984 100644
--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -137,8 +137,36 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(modalias);
 
+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);
+
 static struct attribute *fsl_mc_dev_attrs[] = {
 	&dev_attr_modalias.attr,
+	&dev_attr_rescan.attr,
 	NULL,
 };
 
diff --git a/drivers/bus/fsl-mc/fsl-mc-private.h b/drivers/bus/fsl-mc/fsl-mc-private.h
index 00cca7d..c1fc80e 100644
--- a/drivers/bus/fsl-mc/fsl-mc-private.h
+++ b/drivers/bus/fsl-mc/fsl-mc-private.h
@@ -545,6 +545,9 @@ int __must_check fsl_mc_device_add(struct fsl_mc_obj_desc *obj_desc,
 
 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);
-- 
1.9.1