cdx: Register cdx bus as a device on cdx subsystem

While scanning for CDX devices, register newly discovered bus as a
cdx device. CDX device attributes are visible based on device type.

Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
Link: https://lore.kernel.org/r/20231017160505.10640-5-abhijit.gangurde@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/cdx/cdx.c

@@ -125,8 +125,13 @@ static int cdx_unregister_device(struct device *dev,
 {
 	struct cdx_device *cdx_dev = to_cdx_device(dev);
 
-	kfree(cdx_dev->driver_override);
+	if (cdx_dev->is_bus) {
-	cdx_dev->driver_override = NULL;
+		device_for_each_child(dev, NULL, cdx_unregister_device);
+	} else {
+		kfree(cdx_dev->driver_override);
+		cdx_dev->driver_override = NULL;
+	}
+
 	/*
 	 * Do not free cdx_dev here as it would be freed in
 	 * cdx_device_release() called from within put_device().
@@ -201,6 +206,9 @@ static int cdx_bus_match(struct device *dev, struct device_driver *drv)
 	const struct cdx_device_id *found_id = NULL;
 	const struct cdx_device_id *ids;
 
+	if (cdx_dev->is_bus)
+		return false;
+
 	ids = cdx_drv->match_id_table;
 
 	/* When driver_override is set, only bind to the matching driver */
@@ -265,10 +273,11 @@ static int cdx_dma_configure(struct device *dev)
 {
 	struct cdx_driver *cdx_drv = to_cdx_driver(dev->driver);
 	struct cdx_device *cdx_dev = to_cdx_device(dev);
+	struct cdx_controller *cdx = cdx_dev->cdx;
 	u32 input_id = cdx_dev->req_id;
 	int ret;
 
-	ret = of_dma_configure_id(dev, dev->parent->of_node, 0, &input_id);
+	ret = of_dma_configure_id(dev, cdx->dev->of_node, 0, &input_id);
 	if (ret && ret != -EPROBE_DEFER) {
 		dev_err(dev, "of_dma_configure_id() failed\n");
 		return ret;
@@ -374,6 +383,18 @@ static ssize_t driver_override_show(struct device *dev,
 }
 static DEVICE_ATTR_RW(driver_override);
 
+static umode_t cdx_dev_attrs_are_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct cdx_device *cdx_dev;
+
+	cdx_dev = to_cdx_device(dev);
+	if (!cdx_dev->is_bus)
+		return a->mode;
+
+	return 0;
+}
+
 static struct attribute *cdx_dev_attrs[] = {
 	&dev_attr_remove.attr,
 	&dev_attr_reset.attr,
@@ -382,7 +403,16 @@ static struct attribute *cdx_dev_attrs[] = {
 	&dev_attr_driver_override.attr,
 	NULL,
 };
-ATTRIBUTE_GROUPS(cdx_dev);
+
+static const struct attribute_group cdx_dev_group = {
+	.attrs = cdx_dev_attrs,
+	.is_visible = cdx_dev_attrs_are_visible,
+};
+
+static const struct attribute_group *cdx_dev_groups[] = {
+	&cdx_dev_group,
+	NULL,
+};
 
 static ssize_t rescan_store(const struct bus_type *bus,
 			    const char *buf, size_t count)
@@ -479,7 +509,6 @@ static void cdx_device_release(struct device *dev)
 int cdx_device_add(struct cdx_dev_params *dev_params)
 {
 	struct cdx_controller *cdx = dev_params->cdx;
-	struct device *parent = cdx->dev;
 	struct cdx_device *cdx_dev;
 	int ret;
 
@@ -503,7 +532,7 @@ int cdx_device_add(struct cdx_dev_params *dev_params)
 
 	/* Initialize generic device */
 	device_initialize(&cdx_dev->dev);
-	cdx_dev->dev.parent = parent;
+	cdx_dev->dev.parent = dev_params->parent;
 	cdx_dev->dev.bus = &cdx_bus_type;
 	cdx_dev->dev.dma_mask = &cdx_dev->dma_mask;
 	cdx_dev->dev.release = cdx_device_release;
@@ -532,6 +561,42 @@ fail:
 }
 EXPORT_SYMBOL_NS_GPL(cdx_device_add, CDX_BUS_CONTROLLER);
 
+struct device *cdx_bus_add(struct cdx_controller *cdx, u8 bus_num)
+{
+	struct cdx_device *cdx_dev;
+	int ret;
+
+	cdx_dev = kzalloc(sizeof(*cdx_dev), GFP_KERNEL);
+	if (!cdx_dev)
+		return NULL;
+
+	device_initialize(&cdx_dev->dev);
+	cdx_dev->cdx = cdx;
+
+	cdx_dev->dev.parent = cdx->dev;
+	cdx_dev->dev.bus = &cdx_bus_type;
+	cdx_dev->dev.release = cdx_device_release;
+	cdx_dev->is_bus = true;
+	cdx_dev->bus_num = bus_num;
+
+	dev_set_name(&cdx_dev->dev, "cdx-%02x",
+		     ((cdx->id << CDX_CONTROLLER_ID_SHIFT) | (bus_num & CDX_BUS_NUM_MASK)));
+
+	ret = device_add(&cdx_dev->dev);
+	if (ret) {
+		dev_err(&cdx_dev->dev, "cdx bus device add failed: %d\n", ret);
+		goto device_add_fail;
+	}
+
+	return &cdx_dev->dev;
+
+device_add_fail:
+	put_device(&cdx_dev->dev);
+
+	return NULL;
+}
+EXPORT_SYMBOL_NS_GPL(cdx_bus_add, CDX_BUS_CONTROLLER);
+
 int cdx_register_controller(struct cdx_controller *cdx)
 {
 	int ret;

drivers/cdx/cdx.h

@@ -13,7 +13,7 @@
 /**
  * struct cdx_dev_params - CDX device parameters
  * @cdx: CDX controller associated with the device
- * @parent: Associated CDX controller
+ * @parent: Associated CDX Bus device
  * @vendor: Vendor ID for CDX device
  * @device: Device ID for CDX device
  * @bus_num: Bus number for this CDX device
@@ -24,6 +24,7 @@
  */
 struct cdx_dev_params {
 	struct cdx_controller *cdx;
+	struct device *parent;
 	u16 vendor;
 	u16 device;
 	u8 bus_num;
@@ -59,4 +60,15 @@ void cdx_unregister_controller(struct cdx_controller *cdx);
  */
 int cdx_device_add(struct cdx_dev_params *dev_params);
 
+/**
+ * cdx_bus_add - Add a CDX bus. This function adds a bus on the CDX bus
+ *		subsystem. It creates a CDX device for the corresponding bus and
+ *		also registers an associated Linux generic device.
+ * @cdx: Associated CDX controller
+ * @us_num: Bus number
+ *
+ * Return: associated Linux generic device pointer on success or NULL on failure.
+ */
+struct device *cdx_bus_add(struct cdx_controller *cdx, u8 bus_num);
+
 #endif /* _CDX_H_ */

drivers/cdx/controller/cdx_controller.c

@@ -79,8 +79,14 @@ static int cdx_scan_devices(struct cdx_controller *cdx)
 	num_cdx_bus = (u8)ret;
 
 	for (bus_num = 0; bus_num < num_cdx_bus; bus_num++) {
+		struct device *bus_dev;
 		u8 num_cdx_dev;
 
+		/* Add the bus on cdx subsystem */
+		bus_dev = cdx_bus_add(cdx, bus_num);
+		if (!bus_dev)
+			continue;
+
 		/* MCDI FW Read: Fetch the number of devices present */
 		ret = cdx_mcdi_get_num_devs(cdx_mcdi, bus_num);
 		if (ret < 0) {
@@ -103,6 +109,7 @@ static int cdx_scan_devices(struct cdx_controller *cdx)
 				continue;
 			}
 			dev_params.cdx = cdx;
+			dev_params.parent = bus_dev;
 
 			/* Add the device to the cdx bus */
 			ret = cdx_device_add(&dev_params);

include/linux/cdx/cdx_bus.h

@@ -88,6 +88,7 @@ struct cdx_controller {
  * @dma_mask: Default DMA mask
  * @flags: CDX device flags
  * @req_id: Requestor ID associated with CDX device
+ * @is_bus: Is this bus device
  * @driver_override: driver name to force a match; do not set directly,
  *                   because core frees it; use driver_set_override() to
  *                   set or clear it.
@@ -104,6 +105,7 @@ struct cdx_device {
 	u64 dma_mask;
 	u16 flags;
 	u32 req_id;
+	bool is_bus;
 	const char *driver_override;
 };