bus: fsl-mc: add autorescan sysfs

Add the autorescan sysfs in order to enable/disable the DPRC IRQs on
which automatic rescan of the bus is performed. This is important when
dynamic creation of objects is needed to happen in a timely manner because
object creation can be bundled together.

Acked-by: Laurentiu Tudor <[e-mail]>
Signed-off-by: Ioana Ciornei <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

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

···
 		synchronize the objects under fsl-mc bus and the
 		Management Complex firmware.
 Users:		Userspace drivers and management tools
+
+What:		/sys/bus/fsl-mc/autorescan
+Date:		January 2021
+KernelVersion:	5.12
+Contact:	Ioana Ciornei <[e-mail]>
+Description:	Writing a zero value to this attribute will
+		disable the DPRC IRQs on which automatic rescan
+		of the fsl-mc bus is performed. A non-zero value
+		will enable the DPRC IRQs.
+Users:		Userspace drivers and management tools

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

···
 /*
  * Disable and clear interrupt for a given DPRC object
  */
-static int disable_dprc_irq(struct fsl_mc_device *mc_dev)
+int disable_dprc_irq(struct fsl_mc_device *mc_dev)
 {
+	struct fsl_mc_bus *mc_bus = to_fsl_mc_bus(mc_dev);
 	int error;
 	struct fsl_mc_io *mc_io = mc_dev->mc_io;
 
···
 		return error;
 	}
 
+	mc_bus->irq_enabled = 0;
+
 	return 0;
+}
+
+int get_dprc_irq_state(struct fsl_mc_device *mc_dev)
+{
+	struct fsl_mc_bus *mc_bus = to_fsl_mc_bus(mc_dev);
+
+	return mc_bus->irq_enabled;
 }
 
 static int register_dprc_irq_handler(struct fsl_mc_device *mc_dev)
···
 	return 0;
 }
 
-static int enable_dprc_irq(struct fsl_mc_device *mc_dev)
+int enable_dprc_irq(struct fsl_mc_device *mc_dev)
 {
+	struct fsl_mc_bus *mc_bus = to_fsl_mc_bus(mc_dev);
 	int error;
 
 	/*
···
 
 		return error;
 	}
+
+	mc_bus->irq_enabled = 1;
 
 	return 0;
 }

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

···
 }
 static BUS_ATTR_WO(rescan);
 
+static int fsl_mc_bus_set_autorescan(struct device *dev, void *data)
+{
+	struct fsl_mc_device *root_mc_dev;
+	unsigned long val;
+	char *buf = data;
+
+	if (!fsl_mc_is_root_dprc(dev))
+		goto exit;
+
+	root_mc_dev = to_fsl_mc_device(dev);
+
+	if (kstrtoul(buf, 0, &val) < 0)
+		return -EINVAL;
+
+	if (val)
+		enable_dprc_irq(root_mc_dev);
+	else
+		disable_dprc_irq(root_mc_dev);
+
+exit:
+	return 0;
+}
+
+static int fsl_mc_bus_get_autorescan(struct device *dev, void *data)
+{
+	struct fsl_mc_device *root_mc_dev;
+	char *buf = data;
+
+	if (!fsl_mc_is_root_dprc(dev))
+		goto exit;
+
+	root_mc_dev = to_fsl_mc_device(dev);
+
+	sprintf(buf, "%d\n", get_dprc_irq_state(root_mc_dev));
+exit:
+	return 0;
+}
+
+static ssize_t autorescan_store(struct bus_type *bus,
+				const char *buf, size_t count)
+{
+	bus_for_each_dev(bus, NULL, (void *)buf, fsl_mc_bus_set_autorescan);
+
+	return count;
+}
+
+static ssize_t autorescan_show(struct bus_type *bus, char *buf)
+{
+	bus_for_each_dev(bus, NULL, (void *)buf, fsl_mc_bus_get_autorescan);
+	return strlen(buf);
+}
+
+static BUS_ATTR_RW(autorescan);
+
 static struct attribute *fsl_mc_bus_attrs[] = {
 	&bus_attr_rescan.attr,
+	&bus_attr_autorescan.attr,
 	NULL,
 };
 

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

···
 	struct mutex scan_mutex;    /* serializes bus scanning */
 	struct dprc_attributes dprc_attr;
 	struct fsl_mc_uapi uapi_misc;
+	int irq_enabled;
 };
 
 #define to_fsl_mc_bus(_mc_dev) \
···
 }
 
 #endif
+
+int disable_dprc_irq(struct fsl_mc_device *mc_dev);
+int enable_dprc_irq(struct fsl_mc_device *mc_dev);
+int get_dprc_irq_state(struct fsl_mc_device *mc_dev);
 
 #endif /* _FSL_MC_PRIVATE_H_ */