Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2698 insertions, 0 deletions

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
new file mode 100644
index 000000000..fe06dc193
--- /dev/null
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -0,0 +1,2698 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Message Protocol driver
+ *
+ * SCMI Message Protocol is used between the System Control Processor(SCP)
+ * and the Application Processors(AP). The Message Handling Unit(MHU)
+ * provides a mechanism for inter-processor communication between SCP's
+ * Cortex M3 and AP.
+ *
+ * SCP offers control and management of the core/cluster power states,
+ * various power domain DVFS including the core/cluster, certain system
+ * clocks configuration, thermal sensors and many others.
+ *
+ * Copyright (C) 2018-2021 ARM Ltd.
+ */
+
+#include <linux/bitmap.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/idr.h>
+#include <linux/io.h>
+#include <linux/io-64-nonatomic-hi-lo.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/hashtable.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/processor.h>
+#include <linux/refcount.h>
+#include <linux/slab.h>
+
+#include "common.h"
+#include "notify.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/scmi.h>
+
+enum scmi_error_codes {
+	SCMI_SUCCESS = 0,	/* Success */
+	SCMI_ERR_SUPPORT = -1,	/* Not supported */
+	SCMI_ERR_PARAMS = -2,	/* Invalid Parameters */
+	SCMI_ERR_ACCESS = -3,	/* Invalid access/permission denied */
+	SCMI_ERR_ENTRY = -4,	/* Not found */
+	SCMI_ERR_RANGE = -5,	/* Value out of range */
+	SCMI_ERR_BUSY = -6,	/* Device busy */
+	SCMI_ERR_COMMS = -7,	/* Communication Error */
+	SCMI_ERR_GENERIC = -8,	/* Generic Error */
+	SCMI_ERR_HARDWARE = -9,	/* Hardware Error */
+	SCMI_ERR_PROTOCOL = -10,/* Protocol Error */
+};
+
+/* List of all SCMI devices active in system */
+static LIST_HEAD(scmi_list);
+/* Protection for the entire list */
+static DEFINE_MUTEX(scmi_list_mutex);
+/* Track the unique id for the transfers for debug & profiling purpose */
+static atomic_t transfer_last_id;
+
+static DEFINE_IDR(scmi_requested_devices);
+static DEFINE_MUTEX(scmi_requested_devices_mtx);
+
+/* Track globally the creation of SCMI SystemPower related devices */
+static bool scmi_syspower_registered;
+/* Protect access to scmi_syspower_registered */
+static DEFINE_MUTEX(scmi_syspower_mtx);
+
+struct scmi_requested_dev {
+	const struct scmi_device_id *id_table;
+	struct list_head node;
+};
+
+/**
+ * struct scmi_xfers_info - Structure to manage transfer information
+ *
+ * @xfer_alloc_table: Bitmap table for allocated messages.
+ *	Index of this bitmap table is also used for message
+ *	sequence identifier.
+ * @xfer_lock: Protection for message allocation
+ * @max_msg: Maximum number of messages that can be pending
+ * @free_xfers: A free list for available to use xfers. It is initialized with
+ *		a number of xfers equal to the maximum allowed in-flight
+ *		messages.
+ * @pending_xfers: An hashtable, indexed by msg_hdr.seq, used to keep all the
+ *		   currently in-flight messages.
+ */
+struct scmi_xfers_info {
+	unsigned long *xfer_alloc_table;
+	spinlock_t xfer_lock;
+	int max_msg;
+	struct hlist_head free_xfers;
+	DECLARE_HASHTABLE(pending_xfers, SCMI_PENDING_XFERS_HT_ORDER_SZ);
+};
+
+/**
+ * struct scmi_protocol_instance  - Describe an initialized protocol instance.
+ * @handle: Reference to the SCMI handle associated to this protocol instance.
+ * @proto: A reference to the protocol descriptor.
+ * @gid: A reference for per-protocol devres management.
+ * @users: A refcount to track effective users of this protocol.
+ * @priv: Reference for optional protocol private data.
+ * @ph: An embedded protocol handle that will be passed down to protocol
+ *	initialization code to identify this instance.
+ *
+ * Each protocol is initialized independently once for each SCMI platform in
+ * which is defined by DT and implemented by the SCMI server fw.
+ */
+struct scmi_protocol_instance {
+	const struct scmi_handle	*handle;
+	const struct scmi_protocol	*proto;
+	void				*gid;
+	refcount_t			users;
+	void				*priv;
+	struct scmi_protocol_handle	ph;
+};
+
+#define ph_to_pi(h)	container_of(h, struct scmi_protocol_instance, ph)
+
+/**
+ * struct scmi_info - Structure representing a SCMI instance
+ *
+ * @dev: Device pointer
+ * @desc: SoC description for this instance
+ * @version: SCMI revision information containing protocol version,
+ *	implementation version and (sub-)vendor identification.
+ * @handle: Instance of SCMI handle to send to clients
+ * @tx_minfo: Universal Transmit Message management info
+ * @rx_minfo: Universal Receive Message management 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: IDR for protocols' instance descriptors initialized for
+ *	       this SCMI instance: populated on protocol's first attempted
+ *	       usage.
+ * @protocols_mtx: A mutex to protect protocols instances initialization.
+ * @protocols_imp: List of protocols implemented, currently maximum of
+ *		   scmi_revision_info.num_protocols elements allocated by the
+ *		   base protocol
+ * @active_protocols: IDR storing device_nodes for protocols actually defined
+ *		      in the DT and confirmed as implemented by fw.
+ * @atomic_threshold: Optional system wide DT-configured threshold, expressed
+ *		      in microseconds, for atomic operations.
+ *		      Only SCMI synchronous commands reported by the platform
+ *		      to have an execution latency lesser-equal to the threshold
+ *		      should be considered for atomic mode operation: such
+ *		      decision is finally left up to the SCMI drivers.
+ * @notify_priv: Pointer to private data structure specific to notifications.
+ * @node: List head
+ * @users: Number of users of this instance
+ */
+struct scmi_info {
+	struct device *dev;
+	const struct scmi_desc *desc;
+	struct scmi_revision_info version;
+	struct scmi_handle handle;
+	struct scmi_xfers_info tx_minfo;
+	struct scmi_xfers_info rx_minfo;
+	struct idr tx_idr;
+	struct idr rx_idr;
+	struct idr protocols;
+	/* Ensure mutual exclusive access to protocols instance array */
+	struct mutex protocols_mtx;
+	u8 *protocols_imp;
+	struct idr active_protocols;
+	unsigned int atomic_threshold;
+	void *notify_priv;
+	struct list_head node;
+	int users;
+};
+
+#define handle_to_scmi_info(h)	container_of(h, struct scmi_info, handle)
+
+static const int scmi_linux_errmap[] = {
+	/* better than switch case as long as return value is continuous */
+	0,			/* SCMI_SUCCESS */
+	-EOPNOTSUPP,		/* SCMI_ERR_SUPPORT */
+	-EINVAL,		/* SCMI_ERR_PARAM */
+	-EACCES,		/* SCMI_ERR_ACCESS */
+	-ENOENT,		/* SCMI_ERR_ENTRY */
+	-ERANGE,		/* SCMI_ERR_RANGE */
+	-EBUSY,			/* SCMI_ERR_BUSY */
+	-ECOMM,			/* SCMI_ERR_COMMS */
+	-EIO,			/* SCMI_ERR_GENERIC */
+	-EREMOTEIO,		/* SCMI_ERR_HARDWARE */
+	-EPROTO,		/* SCMI_ERR_PROTOCOL */
+};
+
+static inline int scmi_to_linux_errno(int errno)
+{
+	int err_idx = -errno;
+
+	if (err_idx >= SCMI_SUCCESS && err_idx < ARRAY_SIZE(scmi_linux_errmap))
+		return scmi_linux_errmap[err_idx];
+	return -EIO;
+}
+
+void scmi_notification_instance_data_set(const struct scmi_handle *handle,
+					 void *priv)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	info->notify_priv = priv;
+	/* Ensure updated protocol private date are visible */
+	smp_wmb();
+}
+
+void *scmi_notification_instance_data_get(const struct scmi_handle *handle)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	/* Ensure protocols_private_data has been updated */
+	smp_rmb();
+	return info->notify_priv;
+}
+
+/**
+ * scmi_xfer_token_set  - Reserve and set new token for the xfer at hand
+ *
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
+ * @xfer: The xfer to act upon
+ *
+ * Pick the next unused monotonically increasing token and set it into
+ * xfer->hdr.seq: picking a monotonically increasing value avoids immediate
+ * reuse of freshly completed or timed-out xfers, thus mitigating the risk
+ * of incorrect association of a late and expired xfer with a live in-flight
+ * transaction, both happening to re-use the same token identifier.
+ *
+ * Since platform is NOT required to answer our request in-order we should
+ * account for a few rare but possible scenarios:
+ *
+ *  - exactly 'next_token' may be NOT available so pick xfer_id >= next_token
+ *    using find_next_zero_bit() starting from candidate next_token bit
+ *
+ *  - all tokens ahead upto (MSG_TOKEN_ID_MASK - 1) are used in-flight but we
+ *    are plenty of free tokens at start, so try a second pass using
+ *    find_next_zero_bit() and starting from 0.
+ *
+ *  X = used in-flight
+ *
+ * Normal
+ * ------
+ *
+ *		|- xfer_id picked
+ *   -----------+----------------------------------------------------------
+ *   | | |X|X|X| | | | | | ... ... ... ... ... ... ... ... ... ... ...|X|X|
+ *   ----------------------------------------------------------------------
+ *		^
+ *		|- next_token
+ *
+ * Out-of-order pending at start
+ * -----------------------------
+ *
+ *	  |- xfer_id picked, last_token fixed
+ *   -----+----------------------------------------------------------------
+ *   |X|X| | | | |X|X| ... ... ... ... ... ... ... ... ... ... ... ...|X| |
+ *   ----------------------------------------------------------------------
+ *    ^
+ *    |- next_token
+ *
+ *
+ * Out-of-order pending at end
+ * ---------------------------
+ *
+ *	  |- xfer_id picked, last_token fixed
+ *   -----+----------------------------------------------------------------
+ *   |X|X| | | | |X|X| ... ... ... ... ... ... ... ... ... ... |X|X|X||X|X|
+ *   ----------------------------------------------------------------------
+ *								^
+ *								|- next_token
+ *
+ * Context: Assumes to be called with @xfer_lock already acquired.
+ *
+ * Return: 0 on Success or error
+ */
+static int scmi_xfer_token_set(struct scmi_xfers_info *minfo,
+			       struct scmi_xfer *xfer)
+{
+	unsigned long xfer_id, next_token;
+
+	/*
+	 * Pick a candidate monotonic token in range [0, MSG_TOKEN_MAX - 1]
+	 * using the pre-allocated transfer_id as a base.
+	 * Note that the global transfer_id is shared across all message types
+	 * so there could be holes in the allocated set of monotonic sequence
+	 * numbers, but that is going to limit the effectiveness of the
+	 * mitigation only in very rare limit conditions.
+	 */
+	next_token = (xfer->transfer_id & (MSG_TOKEN_MAX - 1));
+
+	/* Pick the next available xfer_id >= next_token */
+	xfer_id = find_next_zero_bit(minfo->xfer_alloc_table,
+				     MSG_TOKEN_MAX, next_token);
+	if (xfer_id == MSG_TOKEN_MAX) {
+		/*
+		 * After heavily out-of-order responses, there are no free
+		 * tokens ahead, but only at start of xfer_alloc_table so
+		 * try again from the beginning.
+		 */
+		xfer_id = find_next_zero_bit(minfo->xfer_alloc_table,
+					     MSG_TOKEN_MAX, 0);
+		/*
+		 * Something is wrong if we got here since there can be a
+		 * maximum number of (MSG_TOKEN_MAX - 1) in-flight messages
+		 * but we have not found any free token [0, MSG_TOKEN_MAX - 1].
+		 */
+		if (WARN_ON_ONCE(xfer_id == MSG_TOKEN_MAX))
+			return -ENOMEM;
+	}
+
+	/* Update +/- last_token accordingly if we skipped some hole */
+	if (xfer_id != next_token)
+		atomic_add((int)(xfer_id - next_token), &transfer_last_id);
+
+	/* Set in-flight */
+	set_bit(xfer_id, minfo->xfer_alloc_table);
+	xfer->hdr.seq = (u16)xfer_id;
+
+	return 0;
+}
+
+/**
+ * scmi_xfer_token_clear  - Release the token
+ *
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
+ * @xfer: The xfer to act upon
+ */
+static inline void scmi_xfer_token_clear(struct scmi_xfers_info *minfo,
+					 struct scmi_xfer *xfer)
+{
+	clear_bit(xfer->hdr.seq, minfo->xfer_alloc_table);
+}
+
+/**
+ * scmi_xfer_get() - Allocate one message
+ *
+ * @handle: Pointer to SCMI entity handle
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
+ * @set_pending: If true a monotonic token is picked and the xfer is added to
+ *		 the pending hash table.
+ *
+ * Helper function which is used by various message functions that are
+ * exposed to clients of this driver for allocating a message traffic event.
+ *
+ * Picks an xfer from the free list @free_xfers (if any available) and, if
+ * required, sets a monotonically increasing token and stores the inflight xfer
+ * into the @pending_xfers hashtable for later retrieval.
+ *
+ * The successfully initialized xfer is refcounted.
+ *
+ * Context: Holds @xfer_lock while manipulating @xfer_alloc_table and
+ *	    @free_xfers.
+ *
+ * Return: 0 if all went fine, else corresponding error.
+ */
+static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle,
+				       struct scmi_xfers_info *minfo,
+				       bool set_pending)
+{
+	int ret;
+	unsigned long flags;
+	struct scmi_xfer *xfer;
+
+	spin_lock_irqsave(&minfo->xfer_lock, flags);
+	if (hlist_empty(&minfo->free_xfers)) {
+		spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	/* grab an xfer from the free_list */
+	xfer = hlist_entry(minfo->free_xfers.first, struct scmi_xfer, node);
+	hlist_del_init(&xfer->node);
+
+	/*
+	 * Allocate transfer_id early so that can be used also as base for
+	 * monotonic sequence number generation if needed.
+	 */
+	xfer->transfer_id = atomic_inc_return(&transfer_last_id);
+
+	if (set_pending) {
+		/* Pick and set monotonic token */
+		ret = scmi_xfer_token_set(minfo, xfer);
+		if (!ret) {
+			hash_add(minfo->pending_xfers, &xfer->node,
+				 xfer->hdr.seq);
+			xfer->pending = true;
+		} else {
+			dev_err(handle->dev,
+				"Failed to get monotonic token %d\n", ret);
+			hlist_add_head(&xfer->node, &minfo->free_xfers);
+			xfer = ERR_PTR(ret);
+		}
+	}
+
+	if (!IS_ERR(xfer)) {
+		refcount_set(&xfer->users, 1);
+		atomic_set(&xfer->busy, SCMI_XFER_FREE);
+	}
+	spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+
+	return xfer;
+}
+
+/**
+ * __scmi_xfer_put() - Release a message
+ *
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
+ * @xfer: message that was reserved by scmi_xfer_get
+ *
+ * After refcount check, possibly release an xfer, clearing the token slot,
+ * removing xfer from @pending_xfers and putting it back into free_xfers.
+ *
+ * This holds a spinlock to maintain integrity of internal data structures.
+ */
+static void
+__scmi_xfer_put(struct scmi_xfers_info *minfo, struct scmi_xfer *xfer)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&minfo->xfer_lock, flags);
+	if (refcount_dec_and_test(&xfer->users)) {
+		if (xfer->pending) {
+			scmi_xfer_token_clear(minfo, xfer);
+			hash_del(&xfer->node);
+			xfer->pending = false;
+		}
+		hlist_add_head(&xfer->node, &minfo->free_xfers);
+	}
+	spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+}
+
+/**
+ * scmi_xfer_lookup_unlocked  -  Helper to lookup an xfer_id
+ *
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
+ * @xfer_id: Token ID to lookup in @pending_xfers
+ *
+ * Refcounting is untouched.
+ *
+ * Context: Assumes to be called with @xfer_lock already acquired.
+ *
+ * Return: A valid xfer on Success or error otherwise
+ */
+static struct scmi_xfer *
+scmi_xfer_lookup_unlocked(struct scmi_xfers_info *minfo, u16 xfer_id)
+{
+	struct scmi_xfer *xfer = NULL;
+
+	if (test_bit(xfer_id, minfo->xfer_alloc_table))
+		xfer = XFER_FIND(minfo->pending_xfers, xfer_id);
+
+	return xfer ?: ERR_PTR(-EINVAL);
+}
+
+/**
+ * scmi_msg_response_validate  - Validate message type against state of related
+ * xfer
+ *
+ * @cinfo: A reference to the channel descriptor.
+ * @msg_type: Message type to check
+ * @xfer: A reference to the xfer to validate against @msg_type
+ *
+ * This function checks if @msg_type is congruent with the current state of
+ * a pending @xfer; if an asynchronous delayed response is received before the
+ * related synchronous response (Out-of-Order Delayed Response) the missing
+ * synchronous response is assumed to be OK and completed, carrying on with the
+ * Delayed Response: this is done to address the case in which the underlying
+ * SCMI transport can deliver such out-of-order responses.
+ *
+ * Context: Assumes to be called with xfer->lock already acquired.
+ *
+ * Return: 0 on Success, error otherwise
+ */
+static inline int scmi_msg_response_validate(struct scmi_chan_info *cinfo,
+					     u8 msg_type,
+					     struct scmi_xfer *xfer)
+{
+	/*
+	 * Even if a response was indeed expected on this slot at this point,
+	 * a buggy platform could wrongly reply feeding us an unexpected
+	 * delayed response we're not prepared to handle: bail-out safely
+	 * blaming firmware.
+	 */
+	if (msg_type == MSG_TYPE_DELAYED_RESP && !xfer->async_done) {
+		dev_err(cinfo->dev,
+			"Delayed Response for %d not expected! Buggy F/W ?\n",
+			xfer->hdr.seq);
+		return -EINVAL;
+	}
+
+	switch (xfer->state) {
+	case SCMI_XFER_SENT_OK:
+		if (msg_type == MSG_TYPE_DELAYED_RESP) {
+			/*
+			 * Delayed Response expected but delivered earlier.
+			 * Assume message RESPONSE was OK and skip state.
+			 */
+			xfer->hdr.status = SCMI_SUCCESS;
+			xfer->state = SCMI_XFER_RESP_OK;
+			complete(&xfer->done);
+			dev_warn(cinfo->dev,
+				 "Received valid OoO Delayed Response for %d\n",
+				 xfer->hdr.seq);
+		}
+		break;
+	case SCMI_XFER_RESP_OK:
+		if (msg_type != MSG_TYPE_DELAYED_RESP)
+			return -EINVAL;
+		break;
+	case SCMI_XFER_DRESP_OK:
+		/* No further message expected once in SCMI_XFER_DRESP_OK */
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * scmi_xfer_state_update  - Update xfer state
+ *
+ * @xfer: A reference to the xfer to update
+ * @msg_type: Type of message being processed.
+ *
+ * Note that this message is assumed to have been already successfully validated
+ * by @scmi_msg_response_validate(), so here we just update the state.
+ *
+ * Context: Assumes to be called on an xfer exclusively acquired using the
+ *	    busy flag.
+ */
+static inline void scmi_xfer_state_update(struct scmi_xfer *xfer, u8 msg_type)
+{
+	xfer->hdr.type = msg_type;
+
+	/* Unknown command types were already discarded earlier */
+	if (xfer->hdr.type == MSG_TYPE_COMMAND)
+		xfer->state = SCMI_XFER_RESP_OK;
+	else
+		xfer->state = SCMI_XFER_DRESP_OK;
+}
+
+static bool scmi_xfer_acquired(struct scmi_xfer *xfer)
+{
+	int ret;
+
+	ret = atomic_cmpxchg(&xfer->busy, SCMI_XFER_FREE, SCMI_XFER_BUSY);
+
+	return ret == SCMI_XFER_FREE;
+}
+
+/**
+ * scmi_xfer_command_acquire  -  Helper to lookup and acquire a command xfer
+ *
+ * @cinfo: A reference to the channel descriptor.
+ * @msg_hdr: A message header to use as lookup key
+ *
+ * When a valid xfer is found for the sequence number embedded in the provided
+ * msg_hdr, reference counting is properly updated and exclusive access to this
+ * xfer is granted till released with @scmi_xfer_command_release.
+ *
+ * Return: A valid @xfer on Success or error otherwise.
+ */
+static inline struct scmi_xfer *
+scmi_xfer_command_acquire(struct scmi_chan_info *cinfo, u32 msg_hdr)
+{
+	int ret;
+	unsigned long flags;
+	struct scmi_xfer *xfer;
+	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+	struct scmi_xfers_info *minfo = &info->tx_minfo;
+	u8 msg_type = MSG_XTRACT_TYPE(msg_hdr);
+	u16 xfer_id = MSG_XTRACT_TOKEN(msg_hdr);
+
+	/* Are we even expecting this? */
+	spin_lock_irqsave(&minfo->xfer_lock, flags);
+	xfer = scmi_xfer_lookup_unlocked(minfo, xfer_id);
+	if (IS_ERR(xfer)) {
+		dev_err(cinfo->dev,
+			"Message for %d type %d is not expected!\n",
+			xfer_id, msg_type);
+		spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+		return xfer;
+	}
+	refcount_inc(&xfer->users);
+	spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+
+	spin_lock_irqsave(&xfer->lock, flags);
+	ret = scmi_msg_response_validate(cinfo, msg_type, xfer);
+	/*
+	 * If a pending xfer was found which was also in a congruent state with
+	 * the received message, acquire exclusive access to it setting the busy
+	 * flag.
+	 * Spins only on the rare limit condition of concurrent reception of
+	 * RESP and DRESP for the same xfer.
+	 */
+	if (!ret) {
+		spin_until_cond(scmi_xfer_acquired(xfer));
+		scmi_xfer_state_update(xfer, msg_type);
+	}
+	spin_unlock_irqrestore(&xfer->lock, flags);
+
+	if (ret) {
+		dev_err(cinfo->dev,
+			"Invalid message type:%d for %d - HDR:0x%X  state:%d\n",
+			msg_type, xfer_id, msg_hdr, xfer->state);
+		/* On error the refcount incremented above has to be dropped */
+		__scmi_xfer_put(minfo, xfer);
+		xfer = ERR_PTR(-EINVAL);
+	}
+
+	return xfer;
+}
+
+static inline void scmi_xfer_command_release(struct scmi_info *info,
+					     struct scmi_xfer *xfer)
+{
+	atomic_set(&xfer->busy, SCMI_XFER_FREE);
+	__scmi_xfer_put(&info->tx_minfo, xfer);
+}
+
+static inline void scmi_clear_channel(struct scmi_info *info,
+				      struct scmi_chan_info *cinfo)
+{
+	if (info->desc->ops->clear_channel)
+		info->desc->ops->clear_channel(cinfo);
+}
+
+static inline bool is_polling_required(struct scmi_chan_info *cinfo,
+				       struct scmi_info *info)
+{
+	return cinfo->no_completion_irq || info->desc->force_polling;
+}
+
+static inline bool is_transport_polling_capable(struct scmi_info *info)
+{
+	return info->desc->ops->poll_done ||
+		info->desc->sync_cmds_completed_on_ret;
+}
+
+static inline bool is_polling_enabled(struct scmi_chan_info *cinfo,
+				      struct scmi_info *info)
+{
+	return is_polling_required(cinfo, info) &&
+		is_transport_polling_capable(info);
+}
+
+static void scmi_handle_notification(struct scmi_chan_info *cinfo,
+				     u32 msg_hdr, void *priv)
+{
+	struct scmi_xfer *xfer;
+	struct device *dev = cinfo->dev;
+	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+	struct scmi_xfers_info *minfo = &info->rx_minfo;
+	ktime_t ts;
+
+	ts = ktime_get_boottime();
+	xfer = scmi_xfer_get(cinfo->handle, minfo, false);
+	if (IS_ERR(xfer)) {
+		dev_err(dev, "failed to get free message slot (%ld)\n",
+			PTR_ERR(xfer));
+		scmi_clear_channel(info, cinfo);
+		return;
+	}
+
+	unpack_scmi_header(msg_hdr, &xfer->hdr);
+	if (priv)
+		/* Ensure order between xfer->priv store and following ops */
+		smp_store_mb(xfer->priv, priv);
+	info->desc->ops->fetch_notification(cinfo, info->desc->max_msg_size,
+					    xfer);
+
+	trace_scmi_msg_dump(xfer->hdr.protocol_id, xfer->hdr.id, "NOTI",
+			    xfer->hdr.seq, xfer->hdr.status,
+			    xfer->rx.buf, xfer->rx.len);
+
+	scmi_notify(cinfo->handle, xfer->hdr.protocol_id,
+		    xfer->hdr.id, xfer->rx.buf, xfer->rx.len, ts);
+
+	trace_scmi_rx_done(xfer->transfer_id, xfer->hdr.id,
+			   xfer->hdr.protocol_id, xfer->hdr.seq,
+			   MSG_TYPE_NOTIFICATION);
+
+	__scmi_xfer_put(minfo, xfer);
+
+	scmi_clear_channel(info, cinfo);
+}
+
+static void scmi_handle_response(struct scmi_chan_info *cinfo,
+				 u32 msg_hdr, void *priv)
+{
+	struct scmi_xfer *xfer;
+	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+
+	xfer = scmi_xfer_command_acquire(cinfo, msg_hdr);
+	if (IS_ERR(xfer)) {
+		if (MSG_XTRACT_TYPE(msg_hdr) == MSG_TYPE_DELAYED_RESP)
+			scmi_clear_channel(info, cinfo);
+		return;
+	}
+
+	/* rx.len could be shrunk in the sync do_xfer, so reset to maxsz */
+	if (xfer->hdr.type == MSG_TYPE_DELAYED_RESP)
+		xfer->rx.len = info->desc->max_msg_size;
+
+	if (priv)
+		/* Ensure order between xfer->priv store and following ops */
+		smp_store_mb(xfer->priv, priv);
+	info->desc->ops->fetch_response(cinfo, xfer);
+
+	trace_scmi_msg_dump(xfer->hdr.protocol_id, xfer->hdr.id,
+			    xfer->hdr.type == MSG_TYPE_DELAYED_RESP ?
+			    "DLYD" : "RESP",
+			    xfer->hdr.seq, xfer->hdr.status,
+			    xfer->rx.buf, xfer->rx.len);
+
+	trace_scmi_rx_done(xfer->transfer_id, xfer->hdr.id,
+			   xfer->hdr.protocol_id, xfer->hdr.seq,
+			   xfer->hdr.type);
+
+	if (xfer->hdr.type == MSG_TYPE_DELAYED_RESP) {
+		scmi_clear_channel(info, cinfo);
+		complete(xfer->async_done);
+	} else {
+		complete(&xfer->done);
+	}
+
+	scmi_xfer_command_release(info, xfer);
+}
+
+/**
+ * scmi_rx_callback() - callback for receiving messages
+ *
+ * @cinfo: SCMI channel info
+ * @msg_hdr: Message header
+ * @priv: Transport specific private data.
+ *
+ * Processes one received message to appropriate transfer information and
+ * signals completion of the transfer.
+ *
+ * NOTE: This function will be invoked in IRQ context, hence should be
+ * as optimal as possible.
+ */
+void scmi_rx_callback(struct scmi_chan_info *cinfo, u32 msg_hdr, void *priv)
+{
+	u8 msg_type = MSG_XTRACT_TYPE(msg_hdr);
+
+	switch (msg_type) {
+	case MSG_TYPE_NOTIFICATION:
+		scmi_handle_notification(cinfo, msg_hdr, priv);
+		break;
+	case MSG_TYPE_COMMAND:
+	case MSG_TYPE_DELAYED_RESP:
+		scmi_handle_response(cinfo, msg_hdr, priv);
+		break;
+	default:
+		WARN_ONCE(1, "received unknown msg_type:%d\n", msg_type);
+		break;
+	}
+}
+
+/**
+ * xfer_put() - Release a transmit message
+ *
+ * @ph: Pointer to SCMI protocol handle
+ * @xfer: message that was reserved by xfer_get_init
+ */
+static void xfer_put(const struct scmi_protocol_handle *ph,
+		     struct scmi_xfer *xfer)
+{
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+	struct scmi_info *info = handle_to_scmi_info(pi->handle);
+
+	__scmi_xfer_put(&info->tx_minfo, xfer);
+}
+
+static bool scmi_xfer_done_no_timeout(struct scmi_chan_info *cinfo,
+				      struct scmi_xfer *xfer, ktime_t stop)
+{
+	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+
+	/*
+	 * Poll also on xfer->done so that polling can be forcibly terminated
+	 * in case of out-of-order receptions of delayed responses
+	 */
+	return info->desc->ops->poll_done(cinfo, xfer) ||
+	       try_wait_for_completion(&xfer->done) ||
+	       ktime_after(ktime_get(), stop);
+}
+
+/**
+ * scmi_wait_for_message_response  - An helper to group all the possible ways of
+ * waiting for a synchronous message response.
+ *
+ * @cinfo: SCMI channel info
+ * @xfer: Reference to the transfer being waited for.
+ *
+ * Chooses waiting strategy (sleep-waiting vs busy-waiting) depending on
+ * configuration flags like xfer->hdr.poll_completion.
+ *
+ * Return: 0 on Success, error otherwise.
+ */
+static int scmi_wait_for_message_response(struct scmi_chan_info *cinfo,
+					  struct scmi_xfer *xfer)
+{
+	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+	struct device *dev = info->dev;
+	int ret = 0, timeout_ms = info->desc->max_rx_timeout_ms;
+
+	trace_scmi_xfer_response_wait(xfer->transfer_id, xfer->hdr.id,
+				      xfer->hdr.protocol_id, xfer->hdr.seq,
+				      timeout_ms,
+				      xfer->hdr.poll_completion);
+
+	if (xfer->hdr.poll_completion) {
+		/*
+		 * Real polling is needed only if transport has NOT declared
+		 * itself to support synchronous commands replies.
+		 */
+		if (!info->desc->sync_cmds_completed_on_ret) {
+			/*
+			 * Poll on xfer using transport provided .poll_done();
+			 * assumes no completion interrupt was available.
+			 */
+			ktime_t stop = ktime_add_ms(ktime_get(), timeout_ms);
+
+			spin_until_cond(scmi_xfer_done_no_timeout(cinfo,
+								  xfer, stop));
+			if (ktime_after(ktime_get(), stop)) {
+				dev_err(dev,
+					"timed out in resp(caller: %pS) - polling\n",
+					(void *)_RET_IP_);
+				ret = -ETIMEDOUT;
+			}
+		}
+
+		if (!ret) {
+			unsigned long flags;
+
+			/*
+			 * Do not fetch_response if an out-of-order delayed
+			 * response is being processed.
+			 */
+			spin_lock_irqsave(&xfer->lock, flags);
+			if (xfer->state == SCMI_XFER_SENT_OK) {
+				info->desc->ops->fetch_response(cinfo, xfer);
+				xfer->state = SCMI_XFER_RESP_OK;
+			}
+			spin_unlock_irqrestore(&xfer->lock, flags);
+
+			/* Trace polled replies. */
+			trace_scmi_msg_dump(xfer->hdr.protocol_id, xfer->hdr.id,
+					    "RESP",
+					    xfer->hdr.seq, xfer->hdr.status,
+					    xfer->rx.buf, xfer->rx.len);
+		}
+	} else {
+		/* And we wait for the response. */
+		if (!wait_for_completion_timeout(&xfer->done,
+						 msecs_to_jiffies(timeout_ms))) {
+			dev_err(dev, "timed out in resp(caller: %pS)\n",
+				(void *)_RET_IP_);
+			ret = -ETIMEDOUT;
+		}
+	}
+
+	return ret;
+}
+
+/**
+ * do_xfer() - Do one transfer
+ *
+ * @ph: Pointer to SCMI protocol handle
+ * @xfer: Transfer to initiate and wait for response
+ *
+ * Return: -ETIMEDOUT in case of no response, if transmit error,
+ *	return corresponding error, else if all goes well,
+ *	return 0.
+ */
+static int do_xfer(const struct scmi_protocol_handle *ph,
+		   struct scmi_xfer *xfer)
+{
+	int ret;
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+	struct scmi_info *info = handle_to_scmi_info(pi->handle);
+	struct device *dev = info->dev;
+	struct scmi_chan_info *cinfo;
+
+	/* Check for polling request on custom command xfers at first */
+	if (xfer->hdr.poll_completion && !is_transport_polling_capable(info)) {
+		dev_warn_once(dev,
+			      "Polling mode is not supported by transport.\n");
+		return -EINVAL;
+	}
+
+	cinfo = idr_find(&info->tx_idr, pi->proto->id);
+	if (unlikely(!cinfo))
+		return -EINVAL;
+
+	/* True ONLY if also supported by transport. */
+	if (is_polling_enabled(cinfo, info))
+		xfer->hdr.poll_completion = true;
+
+	/*
+	 * Initialise protocol id now from protocol handle to avoid it being
+	 * overridden by mistake (or malice) by the protocol code mangling with
+	 * the scmi_xfer structure prior to this.
+	 */
+	xfer->hdr.protocol_id = pi->proto->id;
+	reinit_completion(&xfer->done);
+
+	trace_scmi_xfer_begin(xfer->transfer_id, xfer->hdr.id,
+			      xfer->hdr.protocol_id, xfer->hdr.seq,
+			      xfer->hdr.poll_completion);
+
+	/* Clear any stale status */
+	xfer->hdr.status = SCMI_SUCCESS;
+	xfer->state = SCMI_XFER_SENT_OK;
+	/*
+	 * Even though spinlocking is not needed here since no race is possible
+	 * on xfer->state due to the monotonically increasing tokens allocation,
+	 * we must anyway ensure xfer->state initialization is not re-ordered
+	 * after the .send_message() to be sure that on the RX path an early
+	 * ISR calling scmi_rx_callback() cannot see an old stale xfer->state.
+	 */
+	smp_mb();
+
+	ret = info->desc->ops->send_message(cinfo, xfer);
+	if (ret < 0) {
+		dev_dbg(dev, "Failed to send message %d\n", ret);
+		return ret;
+	}
+
+	trace_scmi_msg_dump(xfer->hdr.protocol_id, xfer->hdr.id, "CMND",
+			    xfer->hdr.seq, xfer->hdr.status,
+			    xfer->tx.buf, xfer->tx.len);
+
+	ret = scmi_wait_for_message_response(cinfo, xfer);
+	if (!ret && xfer->hdr.status)
+		ret = scmi_to_linux_errno(xfer->hdr.status);
+
+	if (info->desc->ops->mark_txdone)
+		info->desc->ops->mark_txdone(cinfo, ret, xfer);
+
+	trace_scmi_xfer_end(xfer->transfer_id, xfer->hdr.id,
+			    xfer->hdr.protocol_id, xfer->hdr.seq, ret);
+
+	return ret;
+}
+
+static void reset_rx_to_maxsz(const struct scmi_protocol_handle *ph,
+			      struct scmi_xfer *xfer)
+{
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+	struct scmi_info *info = handle_to_scmi_info(pi->handle);
+
+	xfer->rx.len = info->desc->max_msg_size;
+}
+
+#define SCMI_MAX_RESPONSE_TIMEOUT	(2 * MSEC_PER_SEC)
+
+/**
+ * do_xfer_with_response() - Do one transfer and wait until the delayed
+ *	response is received
+ *
+ * @ph: Pointer to SCMI protocol handle
+ * @xfer: Transfer to initiate and wait for response
+ *
+ * Using asynchronous commands in atomic/polling mode should be avoided since
+ * it could cause long busy-waiting here, so ignore polling for the delayed
+ * response and WARN if it was requested for this command transaction since
+ * upper layers should refrain from issuing such kind of requests.
+ *
+ * The only other option would have been to refrain from using any asynchronous
+ * command even if made available, when an atomic transport is detected, and
+ * instead forcibly use the synchronous version (thing that can be easily
+ * attained at the protocol layer), but this would also have led to longer
+ * stalls of the channel for synchronous commands and possibly timeouts.
+ * (in other words there is usually a good reason if a platform provides an
+ *  asynchronous version of a command and we should prefer to use it...just not
+ *  when using atomic/polling mode)
+ *
+ * Return: -ETIMEDOUT in case of no delayed response, if transmit error,
+ *	return corresponding error, else if all goes well, return 0.
+ */
+static int do_xfer_with_response(const struct scmi_protocol_handle *ph,
+				 struct scmi_xfer *xfer)
+{
+	int ret, timeout = msecs_to_jiffies(SCMI_MAX_RESPONSE_TIMEOUT);
+	DECLARE_COMPLETION_ONSTACK(async_response);
+
+	xfer->async_done = &async_response;
+
+	/*
+	 * Delayed responses should not be polled, so an async command should
+	 * not have been used when requiring an atomic/poll context; WARN and
+	 * perform instead a sleeping wait.
+	 * (Note Async + IgnoreDelayedResponses are sent via do_xfer)
+	 */
+	WARN_ON_ONCE(xfer->hdr.poll_completion);
+
+	ret = do_xfer(ph, xfer);
+	if (!ret) {
+		if (!wait_for_completion_timeout(xfer->async_done, timeout)) {
+			dev_err(ph->dev,
+				"timed out in delayed resp(caller: %pS)\n",
+				(void *)_RET_IP_);
+			ret = -ETIMEDOUT;
+		} else if (xfer->hdr.status) {
+			ret = scmi_to_linux_errno(xfer->hdr.status);
+		}
+	}
+
+	xfer->async_done = NULL;
+	return ret;
+}
+
+/**
+ * xfer_get_init() - Allocate and initialise one message for transmit
+ *
+ * @ph: Pointer to SCMI protocol handle
+ * @msg_id: Message identifier
+ * @tx_size: transmit message size
+ * @rx_size: receive message size
+ * @p: pointer to the allocated and initialised message
+ *
+ * This function allocates the message using @scmi_xfer_get and
+ * initialise the header.
+ *
+ * Return: 0 if all went fine with @p pointing to message, else
+ *	corresponding error.
+ */
+static int xfer_get_init(const struct scmi_protocol_handle *ph,
+			 u8 msg_id, size_t tx_size, size_t rx_size,
+			 struct scmi_xfer **p)
+{
+	int ret;
+	struct scmi_xfer *xfer;
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+	struct scmi_info *info = handle_to_scmi_info(pi->handle);
+	struct scmi_xfers_info *minfo = &info->tx_minfo;
+	struct device *dev = info->dev;
+
+	/* Ensure we have sane transfer sizes */
+	if (rx_size > info->desc->max_msg_size ||
+	    tx_size > info->desc->max_msg_size)
+		return -ERANGE;
+
+	xfer = scmi_xfer_get(pi->handle, minfo, true);
+	if (IS_ERR(xfer)) {
+		ret = PTR_ERR(xfer);
+		dev_err(dev, "failed to get free message slot(%d)\n", ret);
+		return ret;
+	}
+
+	xfer->tx.len = tx_size;
+	xfer->rx.len = rx_size ? : info->desc->max_msg_size;
+	xfer->hdr.type = MSG_TYPE_COMMAND;
+	xfer->hdr.id = msg_id;
+	xfer->hdr.poll_completion = false;
+
+	*p = xfer;
+
+	return 0;
+}
+
+/**
+ * version_get() - command to get the revision of the SCMI entity
+ *
+ * @ph: Pointer to SCMI protocol handle
+ * @version: Holds returned version of protocol.
+ *
+ * Updates the SCMI information in the internal data structure.
+ *
+ * Return: 0 if all went fine, else return appropriate error.
+ */
+static int version_get(const struct scmi_protocol_handle *ph, u32 *version)
+{
+	int ret;
+	__le32 *rev_info;
+	struct scmi_xfer *t;
+
+	ret = xfer_get_init(ph, PROTOCOL_VERSION, 0, sizeof(*version), &t);
+	if (ret)
+		return ret;
+
+	ret = do_xfer(ph, t);
+	if (!ret) {
+		rev_info = t->rx.buf;
+		*version = le32_to_cpu(*rev_info);
+	}
+
+	xfer_put(ph, t);
+	return ret;
+}
+
+/**
+ * scmi_set_protocol_priv  - Set protocol specific data at init time
+ *
+ * @ph: A reference to the protocol handle.
+ * @priv: The private data to set.
+ *
+ * Return: 0 on Success
+ */
+static int scmi_set_protocol_priv(const struct scmi_protocol_handle *ph,
+				  void *priv)
+{
+	struct scmi_protocol_instance *pi = ph_to_pi(ph);
+
+	pi->priv = priv;
+
+	return 0;
+}
+
+/**
+ * scmi_get_protocol_priv  - Set protocol specific data at init time
+ *
+ * @ph: A reference to the protocol handle.
+ *
+ * Return: Protocol private data if any was set.
+ */
+static void *scmi_get_protocol_priv(const struct scmi_protocol_handle *ph)
+{
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+
+	return pi->priv;
+}
+
+static const struct scmi_xfer_ops xfer_ops = {
+	.version_get = version_get,
+	.xfer_get_init = xfer_get_init,
+	.reset_rx_to_maxsz = reset_rx_to_maxsz,
+	.do_xfer = do_xfer,
+	.do_xfer_with_response = do_xfer_with_response,
+	.xfer_put = xfer_put,
+};
+
+struct scmi_msg_resp_domain_name_get {
+	__le32 flags;
+	u8 name[SCMI_MAX_STR_SIZE];
+};
+
+/**
+ * scmi_common_extended_name_get  - Common helper to get extended resources name
+ * @ph: A protocol handle reference.
+ * @cmd_id: The specific command ID to use.
+ * @res_id: The specific resource ID to use.
+ * @name: A pointer to the preallocated area where the retrieved name will be
+ *	  stored as a NULL terminated string.
+ * @len: The len in bytes of the @name char array.
+ *
+ * Return: 0 on Succcess
+ */
+static int scmi_common_extended_name_get(const struct scmi_protocol_handle *ph,
+					 u8 cmd_id, u32 res_id, char *name,
+					 size_t len)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_msg_resp_domain_name_get *resp;
+
+	ret = ph->xops->xfer_get_init(ph, cmd_id, sizeof(res_id),
+				      sizeof(*resp), &t);
+	if (ret)
+		goto out;
+
+	put_unaligned_le32(res_id, t->tx.buf);
+	resp = t->rx.buf;
+
+	ret = ph->xops->do_xfer(ph, t);
+	if (!ret)
+		strscpy(name, resp->name, len);
+
+	ph->xops->xfer_put(ph, t);
+out:
+	if (ret)
+		dev_warn(ph->dev,
+			 "Failed to get extended name - id:%u (ret:%d). Using %s\n",
+			 res_id, ret, name);
+	return ret;
+}
+
+/**
+ * struct scmi_iterator  - Iterator descriptor
+ * @msg: A reference to the message TX buffer; filled by @prepare_message with
+ *	 a proper custom command payload for each multi-part command request.
+ * @resp: A reference to the response RX buffer; used by @update_state and
+ *	  @process_response to parse the multi-part replies.
+ * @t: A reference to the underlying xfer initialized and used transparently by
+ *     the iterator internal routines.
+ * @ph: A reference to the associated protocol handle to be used.
+ * @ops: A reference to the custom provided iterator operations.
+ * @state: The current iterator state; used and updated in turn by the iterators
+ *	   internal routines and by the caller-provided @scmi_iterator_ops.
+ * @priv: A reference to optional private data as provided by the caller and
+ *	  passed back to the @@scmi_iterator_ops.
+ */
+struct scmi_iterator {
+	void *msg;
+	void *resp;
+	struct scmi_xfer *t;
+	const struct scmi_protocol_handle *ph;
+	struct scmi_iterator_ops *ops;
+	struct scmi_iterator_state state;
+	void *priv;
+};
+
+static void *scmi_iterator_init(const struct scmi_protocol_handle *ph,
+				struct scmi_iterator_ops *ops,
+				unsigned int max_resources, u8 msg_id,
+				size_t tx_size, void *priv)
+{
+	int ret;
+	struct scmi_iterator *i;
+
+	i = devm_kzalloc(ph->dev, sizeof(*i), GFP_KERNEL);
+	if (!i)
+		return ERR_PTR(-ENOMEM);
+
+	i->ph = ph;
+	i->ops = ops;
+	i->priv = priv;
+
+	ret = ph->xops->xfer_get_init(ph, msg_id, tx_size, 0, &i->t);
+	if (ret) {
+		devm_kfree(ph->dev, i);
+		return ERR_PTR(ret);
+	}
+
+	i->state.max_resources = max_resources;
+	i->msg = i->t->tx.buf;
+	i->resp = i->t->rx.buf;
+
+	return i;
+}
+
+static int scmi_iterator_run(void *iter)
+{
+	int ret = -EINVAL;
+	struct scmi_iterator_ops *iops;
+	const struct scmi_protocol_handle *ph;
+	struct scmi_iterator_state *st;
+	struct scmi_iterator *i = iter;
+
+	if (!i || !i->ops || !i->ph)
+		return ret;
+
+	iops = i->ops;
+	ph = i->ph;
+	st = &i->state;
+
+	do {
+		iops->prepare_message(i->msg, st->desc_index, i->priv);
+		ret = ph->xops->do_xfer(ph, i->t);
+		if (ret)
+			break;
+
+		st->rx_len = i->t->rx.len;
+		ret = iops->update_state(st, i->resp, i->priv);
+		if (ret)
+			break;
+
+		if (st->num_returned > st->max_resources - st->desc_index) {
+			dev_err(ph->dev,
+				"No. of resources can't exceed %d\n",
+				st->max_resources);
+			ret = -EINVAL;
+			break;
+		}
+
+		for (st->loop_idx = 0; st->loop_idx < st->num_returned;
+		     st->loop_idx++) {
+			ret = iops->process_response(ph, i->resp, st, i->priv);
+			if (ret)
+				goto out;
+		}
+
+		st->desc_index += st->num_returned;
+		ph->xops->reset_rx_to_maxsz(ph, i->t);
+		/*
+		 * check for both returned and remaining to avoid infinite
+		 * loop due to buggy firmware
+		 */
+	} while (st->num_returned && st->num_remaining);
+
+out:
+	/* Finalize and destroy iterator */
+	ph->xops->xfer_put(ph, i->t);
+	devm_kfree(ph->dev, i);
+
+	return ret;
+}
+
+struct scmi_msg_get_fc_info {
+	__le32 domain;
+	__le32 message_id;
+};
+
+struct scmi_msg_resp_desc_fc {
+	__le32 attr;
+#define SUPPORTS_DOORBELL(x)		((x) & BIT(0))
+#define DOORBELL_REG_WIDTH(x)		FIELD_GET(GENMASK(2, 1), (x))
+	__le32 rate_limit;
+	__le32 chan_addr_low;
+	__le32 chan_addr_high;
+	__le32 chan_size;
+	__le32 db_addr_low;
+	__le32 db_addr_high;
+	__le32 db_set_lmask;
+	__le32 db_set_hmask;
+	__le32 db_preserve_lmask;
+	__le32 db_preserve_hmask;
+};
+
+static void
+scmi_common_fastchannel_init(const struct scmi_protocol_handle *ph,
+			     u8 describe_id, u32 message_id, u32 valid_size,
+			     u32 domain, void __iomem **p_addr,
+			     struct scmi_fc_db_info **p_db)
+{
+	int ret;
+	u32 flags;
+	u64 phys_addr;
+	u8 size;
+	void __iomem *addr;
+	struct scmi_xfer *t;
+	struct scmi_fc_db_info *db = NULL;
+	struct scmi_msg_get_fc_info *info;
+	struct scmi_msg_resp_desc_fc *resp;
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+
+	if (!p_addr) {
+		ret = -EINVAL;
+		goto err_out;
+	}
+
+	ret = ph->xops->xfer_get_init(ph, describe_id,
+				      sizeof(*info), sizeof(*resp), &t);
+	if (ret)
+		goto err_out;
+
+	info = t->tx.buf;
+	info->domain = cpu_to_le32(domain);
+	info->message_id = cpu_to_le32(message_id);
+
+	/*
+	 * Bail out on error leaving fc_info addresses zeroed; this includes
+	 * the case in which the requested domain/message_id does NOT support
+	 * fastchannels at all.
+	 */
+	ret = ph->xops->do_xfer(ph, t);
+	if (ret)
+		goto err_xfer;
+
+	resp = t->rx.buf;
+	flags = le32_to_cpu(resp->attr);
+	size = le32_to_cpu(resp->chan_size);
+	if (size != valid_size) {
+		ret = -EINVAL;
+		goto err_xfer;
+	}
+
+	phys_addr = le32_to_cpu(resp->chan_addr_low);
+	phys_addr |= (u64)le32_to_cpu(resp->chan_addr_high) << 32;
+	addr = devm_ioremap(ph->dev, phys_addr, size);
+	if (!addr) {
+		ret = -EADDRNOTAVAIL;
+		goto err_xfer;
+	}
+
+	*p_addr = addr;
+
+	if (p_db && SUPPORTS_DOORBELL(flags)) {
+		db = devm_kzalloc(ph->dev, sizeof(*db), GFP_KERNEL);
+		if (!db) {
+			ret = -ENOMEM;
+			goto err_db;
+		}
+
+		size = 1 << DOORBELL_REG_WIDTH(flags);
+		phys_addr = le32_to_cpu(resp->db_addr_low);
+		phys_addr |= (u64)le32_to_cpu(resp->db_addr_high) << 32;
+		addr = devm_ioremap(ph->dev, phys_addr, size);
+		if (!addr) {
+			ret = -EADDRNOTAVAIL;
+			goto err_db_mem;
+		}
+
+		db->addr = addr;
+		db->width = size;
+		db->set = le32_to_cpu(resp->db_set_lmask);
+		db->set |= (u64)le32_to_cpu(resp->db_set_hmask) << 32;
+		db->mask = le32_to_cpu(resp->db_preserve_lmask);
+		db->mask |= (u64)le32_to_cpu(resp->db_preserve_hmask) << 32;
+
+		*p_db = db;
+	}
+
+	ph->xops->xfer_put(ph, t);
+
+	dev_dbg(ph->dev,
+		"Using valid FC for protocol %X [MSG_ID:%u / RES_ID:%u]\n",
+		pi->proto->id, message_id, domain);
+
+	return;
+
+err_db_mem:
+	devm_kfree(ph->dev, db);
+
+err_db:
+	*p_addr = NULL;
+
+err_xfer:
+	ph->xops->xfer_put(ph, t);
+
+err_out:
+	dev_warn(ph->dev,
+		 "Failed to get FC for protocol %X [MSG_ID:%u / RES_ID:%u] - ret:%d. Using regular messaging.\n",
+		 pi->proto->id, message_id, domain, ret);
+}
+
+#define SCMI_PROTO_FC_RING_DB(w)			\
+do {							\
+	u##w val = 0;					\
+							\
+	if (db->mask)					\
+		val = ioread##w(db->addr) & db->mask;	\
+	iowrite##w((u##w)db->set | val, db->addr);	\
+} while (0)
+
+static void scmi_common_fastchannel_db_ring(struct scmi_fc_db_info *db)
+{
+	if (!db || !db->addr)
+		return;
+
+	if (db->width == 1)
+		SCMI_PROTO_FC_RING_DB(8);
+	else if (db->width == 2)
+		SCMI_PROTO_FC_RING_DB(16);
+	else if (db->width == 4)
+		SCMI_PROTO_FC_RING_DB(32);
+	else /* db->width == 8 */
+#ifdef CONFIG_64BIT
+		SCMI_PROTO_FC_RING_DB(64);
+#else
+	{
+		u64 val = 0;
+
+		if (db->mask)
+			val = ioread64_hi_lo(db->addr) & db->mask;
+		iowrite64_hi_lo(db->set | val, db->addr);
+	}
+#endif
+}
+
+static const struct scmi_proto_helpers_ops helpers_ops = {
+	.extended_name_get = scmi_common_extended_name_get,
+	.iter_response_init = scmi_iterator_init,
+	.iter_response_run = scmi_iterator_run,
+	.fastchannel_init = scmi_common_fastchannel_init,
+	.fastchannel_db_ring = scmi_common_fastchannel_db_ring,
+};
+
+/**
+ * scmi_revision_area_get  - Retrieve version memory area.
+ *
+ * @ph: A reference to the protocol handle.
+ *
+ * A helper to grab the version memory area reference during SCMI Base protocol
+ * initialization.
+ *
+ * Return: A reference to the version memory area associated to the SCMI
+ *	   instance underlying this protocol handle.
+ */
+struct scmi_revision_info *
+scmi_revision_area_get(const struct scmi_protocol_handle *ph)
+{
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+
+	return pi->handle->version;
+}
+
+/**
+ * scmi_alloc_init_protocol_instance  - Allocate and initialize a protocol
+ * instance descriptor.
+ * @info: The reference to the related SCMI instance.
+ * @proto: The protocol descriptor.
+ *
+ * Allocate a new protocol instance descriptor, using the provided @proto
+ * description, against the specified SCMI instance @info, and initialize it;
+ * all resources management is handled via a dedicated per-protocol devres
+ * group.
+ *
+ * Context: Assumes to be called with @protocols_mtx already acquired.
+ * Return: A reference to a freshly allocated and initialized protocol instance
+ *	   or ERR_PTR on failure. On failure the @proto reference is at first
+ *	   put using @scmi_protocol_put() before releasing all the devres group.
+ */
+static struct scmi_protocol_instance *
+scmi_alloc_init_protocol_instance(struct scmi_info *info,
+				  const struct scmi_protocol *proto)
+{
+	int ret = -ENOMEM;
+	void *gid;
+	struct scmi_protocol_instance *pi;
+	const struct scmi_handle *handle = &info->handle;
+
+	/* Protocol specific devres group */
+	gid = devres_open_group(handle->dev, NULL, GFP_KERNEL);
+	if (!gid) {
+		scmi_protocol_put(proto->id);
+		goto out;
+	}
+
+	pi = devm_kzalloc(handle->dev, sizeof(*pi), GFP_KERNEL);
+	if (!pi)
+		goto clean;
+
+	pi->gid = gid;
+	pi->proto = proto;
+	pi->handle = handle;
+	pi->ph.dev = handle->dev;
+	pi->ph.xops = &xfer_ops;
+	pi->ph.hops = &helpers_ops;
+	pi->ph.set_priv = scmi_set_protocol_priv;
+	pi->ph.get_priv = scmi_get_protocol_priv;
+	refcount_set(&pi->users, 1);
+	/* proto->init is assured NON NULL by scmi_protocol_register */
+	ret = pi->proto->instance_init(&pi->ph);
+	if (ret)
+		goto clean;
+
+	ret = idr_alloc(&info->protocols, pi, proto->id, proto->id + 1,
+			GFP_KERNEL);
+	if (ret != proto->id)
+		goto clean;
+
+	/*
+	 * Warn but ignore events registration errors since we do not want
+	 * to skip whole protocols if their notifications are messed up.
+	 */
+	if (pi->proto->events) {
+		ret = scmi_register_protocol_events(handle, pi->proto->id,
+						    &pi->ph,
+						    pi->proto->events);
+		if (ret)
+			dev_warn(handle->dev,
+				 "Protocol:%X - Events Registration Failed - err:%d\n",
+				 pi->proto->id, ret);
+	}
+
+	devres_close_group(handle->dev, pi->gid);
+	dev_dbg(handle->dev, "Initialized protocol: 0x%X\n", pi->proto->id);
+
+	return pi;
+
+clean:
+	/* Take care to put the protocol module's owner before releasing all */
+	scmi_protocol_put(proto->id);
+	devres_release_group(handle->dev, gid);
+out:
+	return ERR_PTR(ret);
+}
+
+/**
+ * scmi_get_protocol_instance  - Protocol initialization helper.
+ * @handle: A reference to the SCMI platform instance.
+ * @protocol_id: The protocol being requested.
+ *
+ * In case the required protocol has never been requested before for this
+ * instance, allocate and initialize all the needed structures while handling
+ * resource allocation with a dedicated per-protocol devres subgroup.
+ *
+ * Return: A reference to an initialized protocol instance or error on failure:
+ *	   in particular returns -EPROBE_DEFER when the desired protocol could
+ *	   NOT be found.
+ */
+static struct scmi_protocol_instance * __must_check
+scmi_get_protocol_instance(const struct scmi_handle *handle, u8 protocol_id)
+{
+	struct scmi_protocol_instance *pi;
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	mutex_lock(&info->protocols_mtx);
+	pi = idr_find(&info->protocols, protocol_id);
+
+	if (pi) {
+		refcount_inc(&pi->users);
+	} else {
+		const struct scmi_protocol *proto;
+
+		/* Fails if protocol not registered on bus */
+		proto = scmi_protocol_get(protocol_id);
+		if (proto)
+			pi = scmi_alloc_init_protocol_instance(info, proto);
+		else
+			pi = ERR_PTR(-EPROBE_DEFER);
+	}
+	mutex_unlock(&info->protocols_mtx);
+
+	return pi;
+}
+
+/**
+ * scmi_protocol_acquire  - Protocol acquire
+ * @handle: A reference to the SCMI platform instance.
+ * @protocol_id: The protocol being requested.
+ *
+ * Register a new user for the requested protocol on the specified SCMI
+ * platform instance, possibly triggering its initialization on first user.
+ *
+ * Return: 0 if protocol was acquired successfully.
+ */
+int scmi_protocol_acquire(const struct scmi_handle *handle, u8 protocol_id)
+{
+	return PTR_ERR_OR_ZERO(scmi_get_protocol_instance(handle, protocol_id));
+}
+
+/**
+ * scmi_protocol_release  - Protocol de-initialization helper.
+ * @handle: A reference to the SCMI platform instance.
+ * @protocol_id: The protocol being requested.
+ *
+ * Remove one user for the specified protocol and triggers de-initialization
+ * and resources de-allocation once the last user has gone.
+ */
+void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+	struct scmi_protocol_instance *pi;
+
+	mutex_lock(&info->protocols_mtx);
+	pi = idr_find(&info->protocols, protocol_id);
+	if (WARN_ON(!pi))
+		goto out;
+
+	if (refcount_dec_and_test(&pi->users)) {
+		void *gid = pi->gid;
+
+		if (pi->proto->events)
+			scmi_deregister_protocol_events(handle, protocol_id);
+
+		if (pi->proto->instance_deinit)
+			pi->proto->instance_deinit(&pi->ph);
+
+		idr_remove(&info->protocols, protocol_id);
+
+		scmi_protocol_put(protocol_id);
+
+		devres_release_group(handle->dev, gid);
+		dev_dbg(handle->dev, "De-Initialized protocol: 0x%X\n",
+			protocol_id);
+	}
+
+out:
+	mutex_unlock(&info->protocols_mtx);
+}
+
+void scmi_setup_protocol_implemented(const struct scmi_protocol_handle *ph,
+				     u8 *prot_imp)
+{
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+	struct scmi_info *info = handle_to_scmi_info(pi->handle);
+
+	info->protocols_imp = prot_imp;
+}
+
+static bool
+scmi_is_protocol_implemented(const struct scmi_handle *handle, u8 prot_id)
+{
+	int i;
+	struct scmi_info *info = handle_to_scmi_info(handle);
+	struct scmi_revision_info *rev = handle->version;
+
+	if (!info->protocols_imp)
+		return false;
+
+	for (i = 0; i < rev->num_protocols; i++)
+		if (info->protocols_imp[i] == prot_id)
+			return true;
+	return false;
+}
+
+struct scmi_protocol_devres {
+	const struct scmi_handle *handle;
+	u8 protocol_id;
+};
+
+static void scmi_devm_release_protocol(struct device *dev, void *res)
+{
+	struct scmi_protocol_devres *dres = res;
+
+	scmi_protocol_release(dres->handle, dres->protocol_id);
+}
+
+static struct scmi_protocol_instance __must_check *
+scmi_devres_protocol_instance_get(struct scmi_device *sdev, u8 protocol_id)
+{
+	struct scmi_protocol_instance *pi;
+	struct scmi_protocol_devres *dres;
+
+	dres = devres_alloc(scmi_devm_release_protocol,
+			    sizeof(*dres), GFP_KERNEL);
+	if (!dres)
+		return ERR_PTR(-ENOMEM);
+
+	pi = scmi_get_protocol_instance(sdev->handle, protocol_id);
+	if (IS_ERR(pi)) {
+		devres_free(dres);
+		return pi;
+	}
+
+	dres->handle = sdev->handle;
+	dres->protocol_id = protocol_id;
+	devres_add(&sdev->dev, dres);
+
+	return pi;
+}
+
+/**
+ * scmi_devm_protocol_get  - Devres managed get protocol operations and handle
+ * @sdev: A reference to an scmi_device whose embedded struct device is to
+ *	  be used for devres accounting.
+ * @protocol_id: The protocol being requested.
+ * @ph: A pointer reference used to pass back the associated protocol handle.
+ *
+ * Get hold of a protocol accounting for its usage, eventually triggering its
+ * initialization, and returning the protocol specific operations and related
+ * protocol handle which will be used as first argument in most of the
+ * protocols operations methods.
+ * Being a devres based managed method, protocol hold will be automatically
+ * released, and possibly de-initialized on last user, once the SCMI driver
+ * owning the scmi_device is unbound from it.
+ *
+ * Return: A reference to the requested protocol operations or error.
+ *	   Must be checked for errors by caller.
+ */
+static const void __must_check *
+scmi_devm_protocol_get(struct scmi_device *sdev, u8 protocol_id,
+		       struct scmi_protocol_handle **ph)
+{
+	struct scmi_protocol_instance *pi;
+
+	if (!ph)
+		return ERR_PTR(-EINVAL);
+
+	pi = scmi_devres_protocol_instance_get(sdev, protocol_id);
+	if (IS_ERR(pi))
+		return pi;
+
+	*ph = &pi->ph;
+
+	return pi->proto->ops;
+}
+
+/**
+ * scmi_devm_protocol_acquire  - Devres managed helper to get hold of a protocol
+ * @sdev: A reference to an scmi_device whose embedded struct device is to
+ *	  be used for devres accounting.
+ * @protocol_id: The protocol being requested.
+ *
+ * Get hold of a protocol accounting for its usage, possibly triggering its
+ * initialization but without getting access to its protocol specific operations
+ * and handle.
+ *
+ * Being a devres based managed method, protocol hold will be automatically
+ * released, and possibly de-initialized on last user, once the SCMI driver
+ * owning the scmi_device is unbound from it.
+ *
+ * Return: 0 on SUCCESS
+ */
+static int __must_check scmi_devm_protocol_acquire(struct scmi_device *sdev,
+						   u8 protocol_id)
+{
+	struct scmi_protocol_instance *pi;
+
+	pi = scmi_devres_protocol_instance_get(sdev, protocol_id);
+	if (IS_ERR(pi))
+		return PTR_ERR(pi);
+
+	return 0;
+}
+
+static int scmi_devm_protocol_match(struct device *dev, void *res, void *data)
+{
+	struct scmi_protocol_devres *dres = res;
+
+	if (WARN_ON(!dres || !data))
+		return 0;
+
+	return dres->protocol_id == *((u8 *)data);
+}
+
+/**
+ * scmi_devm_protocol_put  - Devres managed put protocol operations and handle
+ * @sdev: A reference to an scmi_device whose embedded struct device is to
+ *	  be used for devres accounting.
+ * @protocol_id: The protocol being requested.
+ *
+ * Explicitly release a protocol hold previously obtained calling the above
+ * @scmi_devm_protocol_get.
+ */
+static void scmi_devm_protocol_put(struct scmi_device *sdev, u8 protocol_id)
+{
+	int ret;
+
+	ret = devres_release(&sdev->dev, scmi_devm_release_protocol,
+			     scmi_devm_protocol_match, &protocol_id);
+	WARN_ON(ret);
+}
+
+/**
+ * scmi_is_transport_atomic  - Method to check if underlying transport for an
+ * SCMI instance is configured as atomic.
+ *
+ * @handle: A reference to the SCMI platform instance.
+ * @atomic_threshold: An optional return value for the system wide currently
+ *		      configured threshold for atomic operations.
+ *
+ * Return: True if transport is configured as atomic
+ */
+static bool scmi_is_transport_atomic(const struct scmi_handle *handle,
+				     unsigned int *atomic_threshold)
+{
+	bool ret;
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	ret = info->desc->atomic_enabled && is_transport_polling_capable(info);
+	if (ret && atomic_threshold)
+		*atomic_threshold = info->atomic_threshold;
+
+	return ret;
+}
+
+static inline
+struct scmi_handle *scmi_handle_get_from_info_unlocked(struct scmi_info *info)
+{
+	info->users++;
+	return &info->handle;
+}
+
+/**
+ * scmi_handle_get() - Get the SCMI handle for a device
+ *
+ * @dev: pointer to device for which we want SCMI handle
+ *
+ * NOTE: The function does not track individual clients of the framework
+ * and is expected to be maintained by caller of SCMI protocol library.
+ * scmi_handle_put must be balanced with successful scmi_handle_get
+ *
+ * Return: pointer to handle if successful, NULL on error
+ */
+struct scmi_handle *scmi_handle_get(struct device *dev)
+{
+	struct list_head *p;
+	struct scmi_info *info;
+	struct scmi_handle *handle = NULL;
+
+	mutex_lock(&scmi_list_mutex);
+	list_for_each(p, &scmi_list) {
+		info = list_entry(p, struct scmi_info, node);
+		if (dev->parent == info->dev) {
+			handle = scmi_handle_get_from_info_unlocked(info);
+			break;
+		}
+	}
+	mutex_unlock(&scmi_list_mutex);
+
+	return handle;
+}
+
+/**
+ * scmi_handle_put() - Release the handle acquired by scmi_handle_get
+ *
+ * @handle: handle acquired by scmi_handle_get
+ *
+ * NOTE: The function does not track individual clients of the framework
+ * and is expected to be maintained by caller of SCMI protocol library.
+ * scmi_handle_put must be balanced with successful scmi_handle_get
+ *
+ * Return: 0 is successfully released
+ *	if null was passed, it returns -EINVAL;
+ */
+int scmi_handle_put(const struct scmi_handle *handle)
+{
+	struct scmi_info *info;
+
+	if (!handle)
+		return -EINVAL;
+
+	info = handle_to_scmi_info(handle);
+	mutex_lock(&scmi_list_mutex);
+	if (!WARN_ON(!info->users))
+		info->users--;
+	mutex_unlock(&scmi_list_mutex);
+
+	return 0;
+}
+
+static int __scmi_xfer_info_init(struct scmi_info *sinfo,
+				 struct scmi_xfers_info *info)
+{
+	int i;
+	struct scmi_xfer *xfer;
+	struct device *dev = sinfo->dev;
+	const struct scmi_desc *desc = sinfo->desc;
+
+	/* Pre-allocated messages, no more than what hdr.seq can support */
+	if (WARN_ON(!info->max_msg || info->max_msg > MSG_TOKEN_MAX)) {
+		dev_err(dev,
+			"Invalid maximum messages %d, not in range [1 - %lu]\n",
+			info->max_msg, MSG_TOKEN_MAX);
+		return -EINVAL;
+	}
+
+	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);
+	if (!info->xfer_alloc_table)
+		return -ENOMEM;
+
+	/*
+	 * Preallocate a number of xfers equal to max inflight messages,
+	 * pre-initialize the buffer pointer to pre-allocated buffers and
+	 * attach all of them to the free list
+	 */
+	INIT_HLIST_HEAD(&info->free_xfers);
+	for (i = 0; i < info->max_msg; i++) {
+		xfer = devm_kzalloc(dev, sizeof(*xfer), GFP_KERNEL);
+		if (!xfer)
+			return -ENOMEM;
+
+		xfer->rx.buf = devm_kcalloc(dev, sizeof(u8), desc->max_msg_size,
+					    GFP_KERNEL);
+		if (!xfer->rx.buf)
+			return -ENOMEM;
+
+		xfer->tx.buf = xfer->rx.buf;
+		init_completion(&xfer->done);
+		spin_lock_init(&xfer->lock);
+
+		/* Add initialized xfer to the free list */
+		hlist_add_head(&xfer->node, &info->free_xfers);
+	}
+
+	spin_lock_init(&info->xfer_lock);
+
+	return 0;
+}
+
+static int scmi_channels_max_msg_configure(struct scmi_info *sinfo)
+{
+	const struct scmi_desc *desc = sinfo->desc;
+
+	if (!desc->ops->get_max_msg) {
+		sinfo->tx_minfo.max_msg = desc->max_msg;
+		sinfo->rx_minfo.max_msg = desc->max_msg;
+	} else {
+		struct scmi_chan_info *base_cinfo;
+
+		base_cinfo = idr_find(&sinfo->tx_idr, SCMI_PROTOCOL_BASE);
+		if (!base_cinfo)
+			return -EINVAL;
+		sinfo->tx_minfo.max_msg = desc->ops->get_max_msg(base_cinfo);
+
+		/* RX channel is optional so can be skipped */
+		base_cinfo = idr_find(&sinfo->rx_idr, SCMI_PROTOCOL_BASE);
+		if (base_cinfo)
+			sinfo->rx_minfo.max_msg =
+				desc->ops->get_max_msg(base_cinfo);
+	}
+
+	return 0;
+}
+
+static int scmi_xfer_info_init(struct scmi_info *sinfo)
+{
+	int ret;
+
+	ret = scmi_channels_max_msg_configure(sinfo);
+	if (ret)
+		return ret;
+
+	ret = __scmi_xfer_info_init(sinfo, &sinfo->tx_minfo);
+	if (!ret && !idr_is_empty(&sinfo->rx_idr))
+		ret = __scmi_xfer_info_init(sinfo, &sinfo->rx_minfo);
+
+	return ret;
+}
+
+static int scmi_chan_setup(struct scmi_info *info, struct device *dev,
+			   int prot_id, bool tx)
+{
+	int ret, idx;
+	struct scmi_chan_info *cinfo;
+	struct idr *idr;
+
+	/* Transmit channel is first entry i.e. index 0 */
+	idx = tx ? 0 : 1;
+	idr = tx ? &info->tx_idr : &info->rx_idr;
+
+	/* check if already allocated, used for multiple device per protocol */
+	cinfo = idr_find(idr, prot_id);
+	if (cinfo)
+		return 0;
+
+	if (!info->desc->ops->chan_available(dev, idx)) {
+		cinfo = idr_find(idr, SCMI_PROTOCOL_BASE);
+		if (unlikely(!cinfo)) /* Possible only if platform has no Rx */
+			return -EINVAL;
+		goto idr_alloc;
+	}
+
+	cinfo = devm_kzalloc(info->dev, sizeof(*cinfo), GFP_KERNEL);
+	if (!cinfo)
+		return -ENOMEM;
+
+	cinfo->dev = dev;
+	cinfo->rx_timeout_ms = info->desc->max_rx_timeout_ms;
+
+	ret = info->desc->ops->chan_setup(cinfo, info->dev, tx);
+	if (ret)
+		return ret;
+
+	if (tx && is_polling_required(cinfo, info)) {
+		if (is_transport_polling_capable(info))
+			dev_info(dev,
+				 "Enabled polling mode TX channel - prot_id:%d\n",
+				 prot_id);
+		else
+			dev_warn(dev,
+				 "Polling mode NOT supported by transport.\n");
+	}
+
+idr_alloc:
+	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;
+	}
+
+	cinfo->handle = &info->handle;
+	return 0;
+}
+
+static inline int
+scmi_txrx_setup(struct scmi_info *info, struct device *dev, int prot_id)
+{
+	int ret = scmi_chan_setup(info, dev, prot_id, true);
+
+	if (!ret) {
+		/* Rx is optional, report only memory errors */
+		ret = scmi_chan_setup(info, dev, prot_id, false);
+		if (ret && ret != -ENOMEM)
+			ret = 0;
+	}
+
+	return ret;
+}
+
+/**
+ * scmi_get_protocol_device  - Helper to get/create an SCMI device.
+ *
+ * @np: A device node representing a valid active protocols for the referred
+ * SCMI instance.
+ * @info: The referred SCMI instance for which we are getting/creating this
+ * device.
+ * @prot_id: The protocol ID.
+ * @name: The device name.
+ *
+ * Referring to the specific SCMI instance identified by @info, this helper
+ * takes care to return a properly initialized device matching the requested
+ * @proto_id and @name: if device was still not existent it is created as a
+ * child of the specified SCMI instance @info and its transport properly
+ * initialized as usual.
+ *
+ * Return: A properly initialized scmi device, NULL otherwise.
+ */
+static inline struct scmi_device *
+scmi_get_protocol_device(struct device_node *np, struct scmi_info *info,
+			 int prot_id, const char *name)
+{
+	struct scmi_device *sdev;
+
+	/* Already created for this parent SCMI instance ? */
+	sdev = scmi_child_dev_find(info->dev, prot_id, name);
+	if (sdev)
+		return sdev;
+
+	mutex_lock(&scmi_syspower_mtx);
+	if (prot_id == SCMI_PROTOCOL_SYSTEM && scmi_syspower_registered) {
+		dev_warn(info->dev,
+			 "SCMI SystemPower protocol device must be unique !\n");
+		mutex_unlock(&scmi_syspower_mtx);
+
+		return NULL;
+	}
+
+	pr_debug("Creating SCMI device (%s) for protocol %x\n", name, prot_id);
+
+	sdev = scmi_device_create(np, info->dev, prot_id, name);
+	if (!sdev) {
+		dev_err(info->dev, "failed to create %d protocol device\n",
+			prot_id);
+		mutex_unlock(&scmi_syspower_mtx);
+
+		return NULL;
+	}
+
+	if (scmi_txrx_setup(info, &sdev->dev, prot_id)) {
+		dev_err(&sdev->dev, "failed to setup transport\n");
+		scmi_device_destroy(sdev);
+		mutex_unlock(&scmi_syspower_mtx);
+
+		return NULL;
+	}
+
+	if (prot_id == SCMI_PROTOCOL_SYSTEM)
+		scmi_syspower_registered = true;
+
+	mutex_unlock(&scmi_syspower_mtx);
+
+	return sdev;
+}
+
+static inline void
+scmi_create_protocol_device(struct device_node *np, struct scmi_info *info,
+			    int prot_id, const char *name)
+{
+	struct scmi_device *sdev;
+
+	sdev = scmi_get_protocol_device(np, info, prot_id, name);
+	if (!sdev)
+		return;
+
+	/* setup handle now as the transport is ready */
+	scmi_set_handle(sdev);
+}
+
+/**
+ * scmi_create_protocol_devices  - Create devices for all pending requests for
+ * this SCMI instance.
+ *
+ * @np: The device node describing the protocol
+ * @info: The SCMI instance descriptor
+ * @prot_id: The protocol ID
+ *
+ * All devices previously requested for this instance (if any) are found and
+ * created by scanning the proper @&scmi_requested_devices entry.
+ */
+static void scmi_create_protocol_devices(struct device_node *np,
+					 struct scmi_info *info, int prot_id)
+{
+	struct list_head *phead;
+
+	mutex_lock(&scmi_requested_devices_mtx);
+	phead = idr_find(&scmi_requested_devices, prot_id);
+	if (phead) {
+		struct scmi_requested_dev *rdev;
+
+		list_for_each_entry(rdev, phead, node)
+			scmi_create_protocol_device(np, info, prot_id,
+						    rdev->id_table->name);
+	}
+	mutex_unlock(&scmi_requested_devices_mtx);
+}
+
+/**
+ * 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, then a matching device is created for each already
+ * active SCMI instance. (if any)
+ *
+ * This way the requested device is created straight-away for all the already
+ * initialized(probed) SCMI instances (handles) and it remains also annotated
+ * as pending creation if the requesting SCMI driver was loaded before some
+ * SCMI instance and related transports were available: when such late instance
+ * is probed, its probe will take care to scan the list of pending requested
+ * devices and create those on its own (see @scmi_create_protocol_devices and
+ * its enclosing loop)
+ *
+ * Return: 0 on Success
+ */
+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;
+	struct scmi_info *info;
+
+	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);
+
+	/*
+	 * Now effectively create and initialize the requested device for every
+	 * already initialized SCMI instance which has registered the requested
+	 * protocol as a valid active one: i.e. defined in DT and supported by
+	 * current platform FW.
+	 */
+	mutex_lock(&scmi_list_mutex);
+	list_for_each_entry(info, &scmi_list, node) {
+		struct device_node *child;
+
+		child = idr_find(&info->active_protocols,
+				 id_table->protocol_id);
+		if (child) {
+			struct scmi_device *sdev;
+
+			sdev = scmi_get_protocol_device(child, info,
+							id_table->protocol_id,
+							id_table->name);
+			if (sdev) {
+				/* Set handle if not already set: device existed */
+				if (!sdev->handle)
+					sdev->handle =
+						scmi_handle_get_from_info_unlocked(info);
+				/* Relink consumer and suppliers */
+				if (sdev->handle)
+					scmi_device_link_add(&sdev->dev,
+							     sdev->handle->dev);
+			}
+		} else {
+			dev_err(info->dev,
+				"Failed. SCMI protocol %d not active.\n",
+				id_table->protocol_id);
+		}
+	}
+	mutex_unlock(&scmi_list_mutex);
+
+out:
+	mutex_unlock(&scmi_requested_devices_mtx);
+
+	return ret;
+}
+
+/**
+ * scmi_protocol_device_unrequest  - Helper to unrequest a device
+ *
+ * @id_table: A protocol/name pair descriptor for the device to be unrequested.
+ *
+ * An helper to let an SCMI driver release its request about devices; note that
+ * devices are created and initialized once the first SCMI driver request them
+ * but they destroyed only on SCMI core unloading/unbinding.
+ *
+ * The current SCMI transport layer uses such devices as internal references and
+ * as such they could be shared as same transport between multiple drivers so
+ * that cannot be safely destroyed till the whole SCMI stack is removed.
+ * (unless adding further burden of refcounting.)
+ */
+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);
+				kfree(victim);
+				break;
+			}
+		}
+
+		if (list_empty(phead)) {
+			idr_remove(&scmi_requested_devices,
+				   id_table->protocol_id);
+			kfree(phead);
+		}
+	}
+	mutex_unlock(&scmi_requested_devices_mtx);
+}
+
+static int scmi_cleanup_txrx_channels(struct scmi_info *info)
+{
+	int ret;
+	struct idr *idr = &info->tx_idr;
+
+	ret = idr_for_each(idr, info->desc->ops->chan_free, idr);
+	idr_destroy(&info->tx_idr);
+
+	idr = &info->rx_idr;
+	ret = idr_for_each(idr, info->desc->ops->chan_free, idr);
+	idr_destroy(&info->rx_idr);
+
+	return ret;
+}
+
+static int scmi_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct scmi_handle *handle;
+	const struct scmi_desc *desc;
+	struct scmi_info *info;
+	struct device *dev = &pdev->dev;
+	struct device_node *child, *np = dev->of_node;
+
+	desc = of_device_get_match_data(dev);
+	if (!desc)
+		return -EINVAL;
+
+	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->dev = dev;
+	info->desc = desc;
+	INIT_LIST_HEAD(&info->node);
+	idr_init(&info->protocols);
+	mutex_init(&info->protocols_mtx);
+	idr_init(&info->active_protocols);
+
+	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;
+	handle->devm_protocol_acquire = scmi_devm_protocol_acquire;
+	handle->devm_protocol_get = scmi_devm_protocol_get;
+	handle->devm_protocol_put = scmi_devm_protocol_put;
+
+	/* System wide atomic threshold for atomic ops .. if any */
+	if (!of_property_read_u32(np, "atomic-threshold-us",
+				  &info->atomic_threshold))
+		dev_info(dev,
+			 "SCMI System wide atomic threshold set to %d us\n",
+			 info->atomic_threshold);
+	handle->is_transport_atomic = scmi_is_transport_atomic;
+
+	if (desc->ops->link_supplier) {
+		ret = desc->ops->link_supplier(dev);
+		if (ret)
+			return ret;
+	}
+
+	ret = scmi_txrx_setup(info, dev, SCMI_PROTOCOL_BASE);
+	if (ret)
+		return ret;
+
+	ret = scmi_xfer_info_init(info);
+	if (ret)
+		goto clear_txrx_setup;
+
+	if (scmi_notification_init(handle))
+		dev_err(dev, "SCMI Notifications NOT available.\n");
+
+	if (info->desc->atomic_enabled && !is_transport_polling_capable(info))
+		dev_err(dev,
+			"Transport is not polling capable. Atomic mode not supported.\n");
+
+	/*
+	 * Trigger SCMI Base protocol initialization.
+	 * It's mandatory and won't be ever released/deinit until the
+	 * SCMI stack is shutdown/unloaded as a whole.
+	 */
+	ret = scmi_protocol_acquire(handle, SCMI_PROTOCOL_BASE);
+	if (ret) {
+		dev_err(dev, "unable to communicate with SCMI\n");
+		goto notification_exit;
+	}
+
+	mutex_lock(&scmi_list_mutex);
+	list_add_tail(&info->node, &scmi_list);
+	mutex_unlock(&scmi_list_mutex);
+
+	for_each_available_child_of_node(np, child) {
+		u32 prot_id;
+
+		if (of_property_read_u32(child, "reg", &prot_id))
+			continue;
+
+		if (!FIELD_FIT(MSG_PROTOCOL_ID_MASK, prot_id))
+			dev_err(dev, "Out of range protocol %d\n", prot_id);
+
+		if (!scmi_is_protocol_implemented(handle, prot_id)) {
+			dev_err(dev, "SCMI protocol %d not implemented\n",
+				prot_id);
+			continue;
+		}
+
+		/*
+		 * Save this valid DT protocol descriptor amongst
+		 * @active_protocols for this SCMI instance/
+		 */
+		ret = idr_alloc(&info->active_protocols, child,
+				prot_id, prot_id + 1, GFP_KERNEL);
+		if (ret != prot_id) {
+			dev_err(dev, "SCMI protocol %d already activated. Skip\n",
+				prot_id);
+			continue;
+		}
+
+		of_node_get(child);
+		scmi_create_protocol_devices(child, info, prot_id);
+	}
+
+	return 0;
+
+notification_exit:
+	scmi_notification_exit(&info->handle);
+clear_txrx_setup:
+	scmi_cleanup_txrx_channels(info);
+	return ret;
+}
+
+void scmi_free_channel(struct scmi_chan_info *cinfo, struct idr *idr, int id)
+{
+	idr_remove(idr, id);
+}
+
+static int scmi_remove(struct platform_device *pdev)
+{
+	int ret, id;
+	struct scmi_info *info = platform_get_drvdata(pdev);
+	struct device_node *child;
+
+	mutex_lock(&scmi_list_mutex);
+	if (info->users)
+		dev_warn(&pdev->dev,
+			 "Still active SCMI users will be forcibly unbound.\n");
+	list_del(&info->node);
+	mutex_unlock(&scmi_list_mutex);
+
+	scmi_notification_exit(&info->handle);
+
+	mutex_lock(&info->protocols_mtx);
+	idr_destroy(&info->protocols);
+	mutex_unlock(&info->protocols_mtx);
+
+	idr_for_each_entry(&info->active_protocols, child, id)
+		of_node_put(child);
+	idr_destroy(&info->active_protocols);
+
+	/* Safe to free channels since no more users */
+	ret = scmi_cleanup_txrx_channels(info);
+	if (ret)
+		dev_warn(&pdev->dev, "Failed to cleanup SCMI channels.\n");
+
+	return 0;
+}
+
+static ssize_t protocol_version_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct scmi_info *info = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u.%u\n", info->version.major_ver,
+		       info->version.minor_ver);
+}
+static DEVICE_ATTR_RO(protocol_version);
+
+static ssize_t firmware_version_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct scmi_info *info = dev_get_drvdata(dev);
+
+	return sprintf(buf, "0x%x\n", info->version.impl_ver);
+}
+static DEVICE_ATTR_RO(firmware_version);
+
+static ssize_t vendor_id_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct scmi_info *info = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", info->version.vendor_id);
+}
+static DEVICE_ATTR_RO(vendor_id);
+
+static ssize_t sub_vendor_id_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct scmi_info *info = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", info->version.sub_vendor_id);
+}
+static DEVICE_ATTR_RO(sub_vendor_id);
+
+static struct attribute *versions_attrs[] = {
+	&dev_attr_firmware_version.attr,
+	&dev_attr_protocol_version.attr,
+	&dev_attr_vendor_id.attr,
+	&dev_attr_sub_vendor_id.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(versions);
+
+/* Each compatible listed below must have descriptor associated with it */
+static const struct of_device_id scmi_of_match[] = {
+#ifdef CONFIG_ARM_SCMI_TRANSPORT_MAILBOX
+	{ .compatible = "arm,scmi", .data = &scmi_mailbox_desc },
+#endif
+#ifdef CONFIG_ARM_SCMI_TRANSPORT_OPTEE
+	{ .compatible = "linaro,scmi-optee", .data = &scmi_optee_desc },
+#endif
+#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC
+	{ .compatible = "arm,scmi-smc", .data = &scmi_smc_desc},
+#endif
+#ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
+	{ .compatible = "arm,scmi-virtio", .data = &scmi_virtio_desc},
+#endif
+	{ /* Sentinel */ },
+};
+
+MODULE_DEVICE_TABLE(of, scmi_of_match);
+
+static struct platform_driver scmi_driver = {
+	.driver = {
+		   .name = "arm-scmi",
+		   .suppress_bind_attrs = true,
+		   .of_match_table = scmi_of_match,
+		   .dev_groups = versions_groups,
+		   },
+	.probe = scmi_probe,
+	.remove = scmi_remove,
+};
+
+/**
+ * __scmi_transports_setup  - Common helper to call transport-specific
+ * .init/.exit code if provided.
+ *
+ * @init: A flag to distinguish between init and exit.
+ *
+ * Note that, if provided, we invoke .init/.exit functions for all the
+ * transports currently compiled in.
+ *
+ * Return: 0 on Success.
+ */
+static inline int __scmi_transports_setup(bool init)
+{
+	int ret = 0;
+	const struct of_device_id *trans;
+
+	for (trans = scmi_of_match; trans->data; trans++) {
+		const struct scmi_desc *tdesc = trans->data;
+
+		if ((init && !tdesc->transport_init) ||
+		    (!init && !tdesc->transport_exit))
+			continue;
+
+		if (init)
+			ret = tdesc->transport_init();
+		else
+			tdesc->transport_exit();
+
+		if (ret) {
+			pr_err("SCMI transport %s FAILED initialization!\n",
+			       trans->compatible);
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static int __init scmi_transports_init(void)
+{
+	return __scmi_transports_setup(true);
+}
+
+static void __exit scmi_transports_exit(void)
+{
+	__scmi_transports_setup(false);
+}
+
+static int __init scmi_driver_init(void)
+{
+	int ret;
+
+	/* Bail out if no SCMI transport was configured */
+	if (WARN_ON(!IS_ENABLED(CONFIG_ARM_SCMI_HAVE_TRANSPORT)))
+		return -EINVAL;
+
+	scmi_bus_init();
+
+	/* Initialize any compiled-in transport which provided an init/exit */
+	ret = scmi_transports_init();
+	if (ret)
+		return ret;
+
+	scmi_base_register();
+
+	scmi_clock_register();
+	scmi_perf_register();
+	scmi_power_register();
+	scmi_reset_register();
+	scmi_sensors_register();
+	scmi_voltage_register();
+	scmi_system_register();
+	scmi_powercap_register();
+
+	return platform_driver_register(&scmi_driver);
+}
+subsys_initcall(scmi_driver_init);
+
+static void __exit scmi_driver_exit(void)
+{
+	scmi_base_unregister();
+
+	scmi_clock_unregister();
+	scmi_perf_unregister();
+	scmi_power_unregister();
+	scmi_reset_unregister();
+	scmi_sensors_unregister();
+	scmi_voltage_unregister();
+	scmi_system_unregister();
+	scmi_powercap_unregister();
+
+	scmi_bus_exit();
+
+	scmi_transports_exit();
+
+	platform_driver_unregister(&scmi_driver);
+}
+module_exit(scmi_driver_exit);
+
+MODULE_ALIAS("platform:arm-scmi");
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI protocol driver");
+MODULE_LICENSE("GPL v2");