firmware: arm_scmi: Add receive channel support for notifications

With scmi_mbox_chan_setup enabled to identify and setup both Tx and Rx,
let's consolidate setting up of both the channels under the function
scmi_mbox_txrx_setup.

Since some platforms may opt not to support notifications or delayed
response, they may not need support for Rx. Hence Rx is optional and
failure of setting one up is not considered fatal.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/driver.c

@@ -113,6 +113,7 @@ struct scmi_chan_info {
  *	implementation version and (sub-)vendor identification.
  * @minfo: Message info
  * @tx_idr: IDR object to map protocol id to Tx channel info pointer
+ * @rx_idr: IDR object to map protocol id to Rx channel info pointer
  * @protocols_imp: List of protocols implemented, currently maximum of
  *	MAX_PROTOCOLS_IMP elements allocated by the base protocol
  * @node: List head
@@ -125,6 +126,7 @@ struct scmi_info {
 	struct scmi_handle handle;
 	struct scmi_xfers_info minfo;
 	struct idr tx_idr;
+	struct idr rx_idr;
 	u8 *protocols_imp;
 	struct list_head node;
 	int users;
@@ -655,13 +657,17 @@ static int scmi_mbox_chan_setup(struct scmi_info *info, struct device *dev,
 	struct device_node *shmem, *np = dev->of_node;
 	struct scmi_chan_info *cinfo;
 	struct mbox_client *cl;
+	struct idr *idr;
 	const char *desc = tx ? "Tx" : "Rx";
 
 	/* Transmit channel is first entry i.e. index 0 */
 	idx = tx ? 0 : 1;
+	idr = tx ? &info->tx_idr : &info->rx_idr;
 
 	if (scmi_mailbox_check(np, idx)) {
-		cinfo = idr_find(&info->tx_idr, SCMI_PROTOCOL_BASE);
+		cinfo = idr_find(idr, SCMI_PROTOCOL_BASE);
+		if (unlikely(!cinfo)) /* Possible only if platform has no Rx */
+			return -EINVAL;
 		goto idr_alloc;
 	}
 
@@ -703,7 +709,7 @@ static int scmi_mbox_chan_setup(struct scmi_info *info, struct device *dev,
 	}
 
 idr_alloc:
-	ret = idr_alloc(&info->tx_idr, cinfo, prot_id, prot_id + 1, GFP_KERNEL);
+	ret = idr_alloc(idr, cinfo, prot_id, prot_id + 1, GFP_KERNEL);
 	if (ret != prot_id) {
 		dev_err(dev, "unable to allocate SCMI idr slot err %d\n", ret);
 		return ret;
@@ -713,6 +719,17 @@ idr_alloc:
 	return 0;
 }
 
+static inline int
+scmi_mbox_txrx_setup(struct scmi_info *info, struct device *dev, int prot_id)
+{
+	int ret = scmi_mbox_chan_setup(info, dev, prot_id, true);
+
+	if (!ret) /* Rx is optional, hence no error check */
+		scmi_mbox_chan_setup(info, dev, prot_id, false);
+
+	return ret;
+}
+
 static inline void
 scmi_create_protocol_device(struct device_node *np, struct scmi_info *info,
 			    int prot_id)
@@ -726,7 +743,7 @@ scmi_create_protocol_device(struct device_node *np, struct scmi_info *info,
 		return;
 	}
 
-	if (scmi_mbox_chan_setup(info, &sdev->dev, prot_id, true)) {
+	if (scmi_mbox_txrx_setup(info, &sdev->dev, prot_id)) {
 		dev_err(&sdev->dev, "failed to setup transport\n");
 		scmi_device_destroy(sdev);
 		return;
@@ -769,12 +786,13 @@ static int scmi_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, info);
 	idr_init(&info->tx_idr);
+	idr_init(&info->rx_idr);
 
 	handle = &info->handle;
 	handle->dev = info->dev;
 	handle->version = &info->version;
 
-	ret = scmi_mbox_chan_setup(info, dev, SCMI_PROTOCOL_BASE, true);
+	ret = scmi_mbox_txrx_setup(info, dev, SCMI_PROTOCOL_BASE);
 	if (ret)
 		return ret;
 
@@ -844,6 +862,10 @@ static int scmi_remove(struct platform_device *pdev)
 	ret = idr_for_each(idr, scmi_mbox_free_channel, idr);
 	idr_destroy(&info->tx_idr);
 
+	idr = &info->rx_idr;
+	ret = idr_for_each(idr, scmi_mbox_free_channel, idr);
+	idr_destroy(&info->rx_idr);
+
 	return ret;
 }