Merge tag 'scmi-updates-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into soc/drivers

Arm SCMI updates for v6.4

The main and only new addition this time around is the support for
unidirectional mailbox channels. SCMI communicates between the agent
and the platform using one bidirectional 'a2p' channel used by the agent
to send SCMI commands and synchronously receive the related replies, and
an optional 'p2a' unidirectional channel used to asynchronously receive
delayed responses and notifications emitted from the platform.

In order to support platforms that support only unidirectional mailbox
hardware channels, the existing bindings are extended to support the
same. Both bidirectional and unidirectional channels support for the
SCMI mailbox can coexist. The correct and effective combination of
defined 'mboxes' and 'shmem' descriptors determines the type of the
mailbox channel.

This also contains a fix for the transfers allocation on Rx channel
especially when the base protocol doesn't use Rx channel while some
of the protocols can have dedicated Rx channels.

* tag 'scmi-updates-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
  firmware: arm_scmi: Add support for unidirectional mailbox channels
  dt-bindings: firmware: arm,scmi: Support mailboxes unidirectional channels
  firmware: arm_scmi: Fix xfers allocation on Rx channel
  firmware: arm_scmi: Use the bitmap API to allocate bitmaps
  firmware: arm_scmi: Fix device node validation for mailbox transport
  firmware: arm_scmi: Fix raw coexistence mode behaviour on failure path
  firmware: arm_scmi: Remove duplicate include header inclusion
  firmware: arm_scmi: Return a literal instead of a variable
  firmware: arm_scmi: Clean up a return statement in scmi_probe

Link: https://lore.kernel.org/r/20230417145743.1904318-1-sudeep.holla@arm.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

3 files changed, 124 insertions, 15 deletions

diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 73140b854b31..c15928b8c5cc 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -14,7 +14,6 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/device.h>
-#include <linux/of.h>
 
 #include "common.h"
 
@@ -436,7 +435,7 @@ struct scmi_device *scmi_device_create(struct device_node *np,
 	/* Nothing to do. */
 	if (!phead) {
 		mutex_unlock(&scmi_requested_devices_mtx);
-		return scmi_dev;
+		return NULL;
 	}
 
 	/* Walk the list of requested devices for protocol and create them */
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index d21c7eafd641..e7d97b59963b 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -2221,8 +2221,8 @@ static int __scmi_xfer_info_init(struct scmi_info *sinfo,
 	hash_init(info->pending_xfers);
 
 	/* Allocate a bitmask sized to hold MSG_TOKEN_MAX tokens */
-	info->xfer_alloc_table = devm_kcalloc(dev, BITS_TO_LONGS(MSG_TOKEN_MAX),
-					      sizeof(long), GFP_KERNEL);
+	info->xfer_alloc_table = devm_bitmap_zalloc(dev, MSG_TOKEN_MAX,
+						    GFP_KERNEL);
 	if (!info->xfer_alloc_table)
 		return -ENOMEM;
 
@@ -2289,7 +2289,7 @@ static int scmi_xfer_info_init(struct scmi_info *sinfo)
 		return ret;
 
 	ret = __scmi_xfer_info_init(sinfo, &sinfo->tx_minfo);
-	if (!ret && idr_find(&sinfo->rx_idr, SCMI_PROTOCOL_BASE))
+	if (!ret && !idr_is_empty(&sinfo->rx_idr))
 		ret = __scmi_xfer_info_init(sinfo, &sinfo->rx_minfo);
 
 	return ret;
@@ -2657,6 +2657,7 @@ static int scmi_probe(struct platform_device *pdev)
 	struct scmi_handle *handle;
 	const struct scmi_desc *desc;
 	struct scmi_info *info;
+	bool coex = IS_ENABLED(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT_COEX);
 	struct device *dev = &pdev->dev;
 	struct device_node *child, *np = dev->of_node;
 
@@ -2731,16 +2732,13 @@ static int scmi_probe(struct platform_device *pdev)
 			dev_warn(dev, "Failed to setup SCMI debugfs.\n");
 
 		if (IS_ENABLED(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT)) {
-			bool coex =
-			      IS_ENABLED(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT_COEX);
-
 			ret = scmi_debugfs_raw_mode_setup(info);
 			if (!coex) {
 				if (ret)
 					goto clear_dev_req_notifier;
 
-				/* Bail out anyway when coex enabled */
-				return ret;
+				/* Bail out anyway when coex disabled. */
+				return 0;
 			}
 
 			/* Coex enabled, carry on in any case. */
@@ -2764,6 +2762,8 @@ static int scmi_probe(struct platform_device *pdev)
 	ret = scmi_protocol_acquire(handle, SCMI_PROTOCOL_BASE);
 	if (ret) {
 		dev_err(dev, "unable to communicate with SCMI\n");
+		if (coex)
+			return 0;
 		goto notification_exit;
 	}
 
diff --git a/drivers/firmware/arm_scmi/mailbox.c b/drivers/firmware/arm_scmi/mailbox.c
index 0d9c9538b7f4..1efa5e9392c4 100644
--- a/drivers/firmware/arm_scmi/mailbox.c
+++ b/drivers/firmware/arm_scmi/mailbox.c
@@ -19,13 +19,15 @@
  * struct scmi_mailbox - Structure representing a SCMI mailbox transport
  *
  * @cl: Mailbox Client
- * @chan: Transmit/Receive mailbox channel
+ * @chan: Transmit/Receive mailbox uni/bi-directional channel
+ * @chan_receiver: Optional Receiver mailbox unidirectional channel
  * @cinfo: SCMI channel info
  * @shmem: Transmit/Receive shared memory area
  */
 struct scmi_mailbox {
 	struct mbox_client cl;
 	struct mbox_chan *chan;
+	struct mbox_chan *chan_receiver;
 	struct scmi_chan_info *cinfo;
 	struct scmi_shared_mem __iomem *shmem;
 };
@@ -48,10 +50,98 @@ static void rx_callback(struct mbox_client *cl, void *m)
 
 static bool mailbox_chan_available(struct device_node *of_node, int idx)
 {
+	int num_mb;
+
+	/*
+	 * Just check if bidirrectional channels are involved, and check the
+	 * index accordingly; proper full validation will be made later
+	 * in mailbox_chan_setup().
+	 */
+	num_mb = of_count_phandle_with_args(of_node, "mboxes", "#mbox-cells");
+	if (num_mb == 3 && idx == 1)
+		idx = 2;
+
 	return !of_parse_phandle_with_args(of_node, "mboxes",
 					   "#mbox-cells", idx, NULL);
 }
 
+/**
+ * mailbox_chan_validate  - Validate transport configuration and map channels
+ *
+ * @cdev: Reference to the underlying transport device carrying the
+ *	  of_node descriptor to analyze.
+ * @a2p_rx_chan: A reference to an optional unidirectional channel to use
+ *		 for replies on the a2p channel. Set as zero if not present.
+ * @p2a_chan: A reference to the optional p2a channel.
+ *	      Set as zero if not present.
+ *
+ * At first, validate the transport configuration as described in terms of
+ * 'mboxes' and 'shmem', then determin which mailbox channel indexes are
+ * appropriate to be use in the current configuration.
+ *
+ * Return: 0 on Success or error
+ */
+static int mailbox_chan_validate(struct device *cdev,
+				 int *a2p_rx_chan, int *p2a_chan)
+{
+	int num_mb, num_sh, ret = 0;
+	struct device_node *np = cdev->of_node;
+
+	num_mb = of_count_phandle_with_args(np, "mboxes", "#mbox-cells");
+	num_sh = of_count_phandle_with_args(np, "shmem", NULL);
+	dev_dbg(cdev, "Found %d mboxes and %d shmems !\n", num_mb, num_sh);
+
+	/* Bail out if mboxes and shmem descriptors are inconsistent */
+	if (num_mb <= 0 || num_sh <= 0 || num_sh > 2 || num_mb > 3 ||
+	    (num_mb == 1 && num_sh != 1) || (num_mb == 3 && num_sh != 2)) {
+		dev_warn(cdev,
+			 "Invalid channel descriptor for '%s' - mbs:%d  shm:%d\n",
+			 of_node_full_name(np), num_mb, num_sh);
+		return -EINVAL;
+	}
+
+	/* Bail out if provided shmem descriptors do not refer distinct areas  */
+	if (num_sh > 1) {
+		struct device_node *np_tx, *np_rx;
+
+		np_tx = of_parse_phandle(np, "shmem", 0);
+		np_rx = of_parse_phandle(np, "shmem", 1);
+		if (!np_tx || !np_rx || np_tx == np_rx) {
+			dev_warn(cdev, "Invalid shmem descriptor for '%s'\n",
+				 of_node_full_name(np));
+			ret = -EINVAL;
+		}
+
+		of_node_put(np_tx);
+		of_node_put(np_rx);
+	}
+
+	/* Calculate channels IDs to use depending on mboxes/shmem layout */
+	if (!ret) {
+		switch (num_mb) {
+		case 1:
+			*a2p_rx_chan = 0;
+			*p2a_chan = 0;
+			break;
+		case 2:
+			if (num_sh == 2) {
+				*a2p_rx_chan = 0;
+				*p2a_chan = 1;
+			} else {
+				*a2p_rx_chan = 1;
+				*p2a_chan = 0;
+			}
+			break;
+		case 3:
+			*a2p_rx_chan = 1;
+			*p2a_chan = 2;
+			break;
+		}
+	}
+
+	return ret;
+}
+
 static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
 			      bool tx)
 {
@@ -59,11 +149,18 @@ static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
 	struct device *cdev = cinfo->dev;
 	struct scmi_mailbox *smbox;
 	struct device_node *shmem;
-	int ret, idx = tx ? 0 : 1;
+	int ret, a2p_rx_chan, p2a_chan, idx = tx ? 0 : 1;
 	struct mbox_client *cl;
 	resource_size_t size;
 	struct resource res;
 
+	ret = mailbox_chan_validate(cdev, &a2p_rx_chan, &p2a_chan);
+	if (ret)
+		return ret;
+
+	if (!tx && !p2a_chan)
+		return -ENODEV;
+
 	smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL);
 	if (!smbox)
 		return -ENOMEM;
@@ -93,15 +190,26 @@ static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
 	cl->tx_block = false;
 	cl->knows_txdone = tx;
 
-	smbox->chan = mbox_request_channel(cl, tx ? 0 : 1);
+	smbox->chan = mbox_request_channel(cl, tx ? 0 : p2a_chan);
 	if (IS_ERR(smbox->chan)) {
 		ret = PTR_ERR(smbox->chan);
 		if (ret != -EPROBE_DEFER)
-			dev_err(cdev, "failed to request SCMI %s mailbox\n",
-				tx ? "Tx" : "Rx");
+			dev_err(cdev,
+				"failed to request SCMI %s mailbox\n", desc);
 		return ret;
 	}
 
+	/* Additional unidirectional channel for TX if needed */
+	if (tx && a2p_rx_chan) {
+		smbox->chan_receiver = mbox_request_channel(cl, a2p_rx_chan);
+		if (IS_ERR(smbox->chan_receiver)) {
+			ret = PTR_ERR(smbox->chan_receiver);
+			if (ret != -EPROBE_DEFER)
+				dev_err(cdev, "failed to request SCMI Tx Receiver mailbox\n");
+			return ret;
+		}
+	}
+
 	cinfo->transport_info = smbox;
 	smbox->cinfo = cinfo;
 
@@ -115,8 +223,10 @@ static int mailbox_chan_free(int id, void *p, void *data)
 
 	if (smbox && !IS_ERR(smbox->chan)) {
 		mbox_free_channel(smbox->chan);
+		mbox_free_channel(smbox->chan_receiver);
 		cinfo->transport_info = NULL;
 		smbox->chan = NULL;
+		smbox->chan_receiver = NULL;
 		smbox->cinfo = NULL;
 	}