firmware: arm_scmi: Refactor protocol device creation

Move protocol device request helpers from driver.c compilation unit to
bus.c, so reducing the cross interactions between driver.c and bus.c.

Get rid of old protocol device creation process as a whole from driver.c
and remove also stale SCMI system power unicity checks.

While at that make such helpers call into scmi_requested_devices_nh
notification chain.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-6-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

1 files changed, 156 insertions, 1 deletions

diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index bed566f58029..e63cc1194d43 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -9,6 +9,7 @@
 
 #include <linux/types.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/device.h>
@@ -20,6 +21,160 @@ EXPORT_SYMBOL_GPL(scmi_requested_devices_nh);
 
 static DEFINE_IDA(scmi_bus_id);
 
+static DEFINE_IDR(scmi_requested_devices);
+/* Protect access to scmi_requested_devices */
+static DEFINE_MUTEX(scmi_requested_devices_mtx);
+
+struct scmi_requested_dev {
+	const struct scmi_device_id *id_table;
+	struct list_head node;
+};
+
+/**
+ * scmi_protocol_device_request  - Helper to request a device
+ *
+ * @id_table: A protocol/name pair descriptor for the device to be created.
+ *
+ * This helper let an SCMI driver request specific devices identified by the
+ * @id_table to be created for each active SCMI instance.
+ *
+ * The requested device name MUST NOT be already existent for any protocol;
+ * at first the freshly requested @id_table is annotated in the IDR table
+ * @scmi_requested_devices and then the requested device is advertised to any
+ * registered party via the @scmi_requested_devices_nh notification chain.
+ *
+ * Return: 0 on Success
+ */
+static int scmi_protocol_device_request(const struct scmi_device_id *id_table)
+{
+	int ret = 0;
+	unsigned int id = 0;
+	struct list_head *head, *phead = NULL;
+	struct scmi_requested_dev *rdev;
+
+	pr_debug("Requesting SCMI device (%s) for protocol %x\n",
+		 id_table->name, id_table->protocol_id);
+
+	/*
+	 * Search for the matching protocol rdev list and then search
+	 * of any existent equally named device...fails if any duplicate found.
+	 */
+	mutex_lock(&scmi_requested_devices_mtx);
+	idr_for_each_entry(&scmi_requested_devices, head, id) {
+		if (!phead) {
+			/* A list found registered in the IDR is never empty */
+			rdev = list_first_entry(head, struct scmi_requested_dev,
+						node);
+			if (rdev->id_table->protocol_id ==
+			    id_table->protocol_id)
+				phead = head;
+		}
+		list_for_each_entry(rdev, head, node) {
+			if (!strcmp(rdev->id_table->name, id_table->name)) {
+				pr_err("Ignoring duplicate request [%d] %s\n",
+				       rdev->id_table->protocol_id,
+				       rdev->id_table->name);
+				ret = -EINVAL;
+				goto out;
+			}
+		}
+	}
+
+	/*
+	 * No duplicate found for requested id_table, so let's create a new
+	 * requested device entry for this new valid request.
+	 */
+	rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
+	if (!rdev) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	rdev->id_table = id_table;
+
+	/*
+	 * Append the new requested device table descriptor to the head of the
+	 * related protocol list, eventually creating such head if not already
+	 * there.
+	 */
+	if (!phead) {
+		phead = kzalloc(sizeof(*phead), GFP_KERNEL);
+		if (!phead) {
+			kfree(rdev);
+			ret = -ENOMEM;
+			goto out;
+		}
+		INIT_LIST_HEAD(phead);
+
+		ret = idr_alloc(&scmi_requested_devices, (void *)phead,
+				id_table->protocol_id,
+				id_table->protocol_id + 1, GFP_KERNEL);
+		if (ret != id_table->protocol_id) {
+			pr_err("Failed to save SCMI device - ret:%d\n", ret);
+			kfree(rdev);
+			kfree(phead);
+			ret = -EINVAL;
+			goto out;
+		}
+		ret = 0;
+	}
+	list_add(&rdev->node, phead);
+
+out:
+	mutex_unlock(&scmi_requested_devices_mtx);
+
+	if (!ret)
+		blocking_notifier_call_chain(&scmi_requested_devices_nh,
+					     SCMI_BUS_NOTIFY_DEVICE_REQUEST,
+					     (void *)rdev->id_table);
+
+	return ret;
+}
+
+/**
+ * scmi_protocol_device_unrequest  - Helper to unrequest a device
+ *
+ * @id_table: A protocol/name pair descriptor for the device to be unrequested.
+ *
+ * The unrequested device, described by the provided id_table, is at first
+ * removed from the IDR @scmi_requested_devices and then the removal is
+ * advertised to any registered party via the @scmi_requested_devices_nh
+ * notification chain.
+ */
+static void scmi_protocol_device_unrequest(const struct scmi_device_id *id_table)
+{
+	struct list_head *phead;
+
+	pr_debug("Unrequesting SCMI device (%s) for protocol %x\n",
+		 id_table->name, id_table->protocol_id);
+
+	mutex_lock(&scmi_requested_devices_mtx);
+	phead = idr_find(&scmi_requested_devices, id_table->protocol_id);
+	if (phead) {
+		struct scmi_requested_dev *victim, *tmp;
+
+		list_for_each_entry_safe(victim, tmp, phead, node) {
+			if (!strcmp(victim->id_table->name, id_table->name)) {
+				list_del(&victim->node);
+
+				mutex_unlock(&scmi_requested_devices_mtx);
+				blocking_notifier_call_chain(&scmi_requested_devices_nh,
+							     SCMI_BUS_NOTIFY_DEVICE_UNREQUEST,
+							     (void *)victim->id_table);
+				kfree(victim);
+				mutex_lock(&scmi_requested_devices_mtx);
+				break;
+			}
+		}
+
+		if (list_empty(phead)) {
+			idr_remove(&scmi_requested_devices,
+				   id_table->protocol_id);
+			kfree(phead);
+		}
+	}
+	mutex_unlock(&scmi_requested_devices_mtx);
+}
+
 static const struct scmi_device_id *
 scmi_dev_match_id(struct scmi_device *scmi_dev, struct scmi_driver *scmi_drv)
 {
@@ -124,7 +279,7 @@ int scmi_driver_register(struct scmi_driver *driver, struct module *owner,
 
 	retval = driver_register(&driver->driver);
 	if (!retval)
-		pr_debug("registered new scmi driver %s\n", driver->name);
+		pr_debug("Registered new scmi driver %s\n", driver->name);
 
 	return retval;
 }