Merge tag 'arm-drivers-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc

Pull ARM SoC driver updates from Arnd Bergmann:
 "Updates for SoC specific drivers include a few subsystems that have
  their own maintainers but send them through the soc tree:

  TEE/OP-TEE:
   - Add tracepoints around calls to secure world

  Memory controller drivers:
   - Minor fixes for Renesas, Exynos, Mediatek and Tegra platforms
   - Add debug statistics to Tegra20 memory controller
   - Update Tegra bindings and convert to dtschema

  ARM SCMI Firmware:
   - Support for modular SCMI protocols and vendor specific extensions
   - New SCMI IIO driver
   - Per-cpu DVFS

  The other driver changes are all from the platform maintainers
  directly and reflect the drivers that don't fit into any other
  subsystem as well as treewide changes for a particular platform.

  SoCFPGA:
   - Various cleanups contributed by Krzysztof Kozlowski

  Mediatek:
   - add MT8183 support to mutex driver
   - MMSYS: use per SoC array to describe the possible routing
   - add MMSYS support for MT8183 and MT8167
   - add support for PMIC wrapper with integrated arbiter
   - add support for MT8192/MT6873

  Tegra:
   - Bug fixes to PMC and clock drivers

  NXP/i.MX:
   - Update SCU power domain driver to keep console domain power on.
   - Add missing ADC1 power domain to SCU power domain driver.
   - Update comments for single global power domain in SCU power domain
     driver.
   - Add i.MX51/i.MX53 unique id support to i.MX SoC driver.

  NXP/FSL SoC driver updates for v5.13
   - Add ACPI support for RCPM driver
   - Use generic io{read,write} for QE drivers after performance
     optimized for PowerPC
   - Fix QBMAN probe to cleanup HW states correctly for kexec
   - Various cleanup and style fix for QBMAN/QE/GUTS drivers

  OMAP:
   - Preparation to use devicetree for genpd
   - ti-sysc needs iorange check improved when the interconnect target
     module has no control registers listed
   - ti-sysc needs to probe l4_wkup and l4_cfg interconnects first to
     avoid issues with missing resources and unnecessary deferred probe
   - ti-sysc debug option can now detect more devices
   - ti-sysc now warns if an old incomplete devicetree data is found as
     we now rely on it being complete for am3 and 4
   - soc init code needs to check for prcm and prm nodes for omap4/5 and
     dra7
   - omap-prm driver needs to enable autoidle retention support for
     omap4
   - omap5 clocks are missing gpmc and ocmc clock registers
   - pci-dra7xx now needs to use builtin_platform_driver instead of
     using builtin_platform_driver_probe for deferred probe to work

  Raspberry Pi:
   - Fix-up all RPi firmware drivers so as for unbind to happen in an
     orderly fashion
   - Support for RPi's PoE hat PWM bus

  Qualcomm
   - Improved detection for SCM calling conventions
   - Support for OEM specific wifi firmware path
   - Added drivers for SC7280/SM8350: RPMH, LLCC< AOSS QMP"

* tag 'arm-drivers-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (165 commits)
  soc: aspeed: fix a ternary sign expansion bug
  memory: mtk-smi: Add device-link between smi-larb and smi-common
  memory: samsung: exynos5422-dmc: handle clk_set_parent() failure
  memory: renesas-rpc-if: fix possible NULL pointer dereference of resource
  clk: socfpga: fix iomem pointer cast on 64-bit
  soc: aspeed: Adapt to new LPC device tree layout
  pinctrl: aspeed-g5: Adapt to new LPC device tree layout
  ipmi: kcs: aspeed: Adapt to new LPC DTS layout
  ARM: dts: Remove LPC BMC and Host partitions
  dt-bindings: aspeed-lpc: Remove LPC partitioning
  soc: fsl: enable acpi support in RCPM driver
  soc: qcom: mdt_loader: Detect truncated read of segments
  soc: qcom: mdt_loader: Validate that p_filesz < p_memsz
  soc: qcom: pdr: Fix error return code in pdr_register_listener
  firmware: qcom_scm: Fix kernel-doc function names to match
  firmware: qcom_scm: Suppress sysfs bind attributes
  firmware: qcom_scm: Workaround lack of "is available" call on SC7180
  firmware: qcom_scm: Reduce locking section for __get_convention()
  firmware: qcom_scm: Make __qcom_scm_is_call_available() return bool
  Revert "soc: fsl: qe: introduce qe_io{read,write}* wrappers"
  ...

1 files changed, 725 insertions, 73 deletions

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 3e748e57deab..66eb3f0e5daf 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -11,18 +11,22 @@
  * various power domain DVFS including the core/cluster, certain system
  * clocks configuration, thermal sensors and many others.
  *
- * Copyright (C) 2018 ARM Ltd.
+ * 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/kernel.h>
 #include <linux/ktime.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"
@@ -53,6 +57,14 @@ 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);
+
+struct scmi_requested_dev {
+	const struct scmi_device_id *id_table;
+	struct list_head node;
+};
+
 /**
  * struct scmi_xfers_info - Structure to manage transfer information
  *
@@ -69,6 +81,30 @@ struct scmi_xfers_info {
 };
 
 /**
+ * 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
@@ -80,8 +116,15 @@ struct scmi_xfers_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
  *	MAX_PROTOCOLS_IMP 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.
+ * @notify_priv: Pointer to private data structure specific to notifications.
  * @node: List head
  * @users: Number of users of this instance
  */
@@ -94,7 +137,12 @@ struct scmi_info {
 	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;
+	void *notify_priv;
 	struct list_head node;
 	int users;
 };
@@ -136,6 +184,25 @@ static inline void scmi_dump_header_dbg(struct device *dev,
 		hdr->id, hdr->seq, hdr->protocol_id);
 }
 
+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_get() - Allocate one message
  *
@@ -316,14 +383,16 @@ void scmi_rx_callback(struct scmi_chan_info *cinfo, u32 msg_hdr)
 }
 
 /**
- * scmi_xfer_put() - Release a transmit message
+ * xfer_put() - Release a transmit message
  *
- * @handle: Pointer to SCMI entity handle
+ * @ph: Pointer to SCMI protocol handle
  * @xfer: message that was reserved by scmi_xfer_get
  */
-void scmi_xfer_put(const struct scmi_handle *handle, struct scmi_xfer *xfer)
+static void xfer_put(const struct scmi_protocol_handle *ph,
+		     struct scmi_xfer *xfer)
 {
-	struct scmi_info *info = handle_to_scmi_info(handle);
+	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);
 }
@@ -340,23 +409,32 @@ static bool scmi_xfer_done_no_timeout(struct scmi_chan_info *cinfo,
 }
 
 /**
- * scmi_do_xfer() - Do one transfer
+ * do_xfer() - Do one transfer
  *
- * @handle: Pointer to SCMI entity handle
+ * @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.
  */
-int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer)
+static int do_xfer(const struct scmi_protocol_handle *ph,
+		   struct scmi_xfer *xfer)
 {
 	int ret;
 	int timeout;
-	struct scmi_info *info = handle_to_scmi_info(handle);
+	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;
 
+	/*
+	 * Re-instate protocol id here from protocol handle so that cannot be
+	 * overridden by mistake (or malice) by the protocol code mangling with
+	 * the scmi_xfer structure.
+	 */
+	xfer->hdr.protocol_id = pi->proto->id;
+
 	cinfo = idr_find(&info->tx_idr, xfer->hdr.protocol_id);
 	if (unlikely(!cinfo))
 		return -EINVAL;
@@ -402,10 +480,11 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer)
 	return ret;
 }
 
-void scmi_reset_rx_to_maxsz(const struct scmi_handle *handle,
-			    struct scmi_xfer *xfer)
+static void reset_rx_to_maxsz(const struct scmi_protocol_handle *ph,
+			      struct scmi_xfer *xfer)
 {
-	struct scmi_info *info = handle_to_scmi_info(handle);
+	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;
 }
@@ -413,24 +492,27 @@ void scmi_reset_rx_to_maxsz(const struct scmi_handle *handle,
 #define SCMI_MAX_RESPONSE_TIMEOUT	(2 * MSEC_PER_SEC)
 
 /**
- * scmi_do_xfer_with_response() - Do one transfer and wait until the delayed
+ * do_xfer_with_response() - Do one transfer and wait until the delayed
  *	response is received
  *
- * @handle: Pointer to SCMI entity handle
+ * @ph: Pointer to SCMI protocol handle
  * @xfer: Transfer to initiate and wait for response
  *
  * Return: -ETIMEDOUT in case of no delayed response, if transmit error,
  *	return corresponding error, else if all goes well, return 0.
  */
-int scmi_do_xfer_with_response(const struct scmi_handle *handle,
-			       struct scmi_xfer *xfer)
+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);
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
 	DECLARE_COMPLETION_ONSTACK(async_response);
 
+	xfer->hdr.protocol_id = pi->proto->id;
+
 	xfer->async_done = &async_response;
 
-	ret = scmi_do_xfer(handle, xfer);
+	ret = do_xfer(ph, xfer);
 	if (!ret && !wait_for_completion_timeout(xfer->async_done, timeout))
 		ret = -ETIMEDOUT;
 
@@ -439,11 +521,10 @@ int scmi_do_xfer_with_response(const struct scmi_handle *handle,
 }
 
 /**
- * scmi_xfer_get_init() - Allocate and initialise one message for transmit
+ * xfer_get_init() - Allocate and initialise one message for transmit
  *
- * @handle: Pointer to SCMI entity handle
+ * @ph: Pointer to SCMI protocol handle
  * @msg_id: Message identifier
- * @prot_id: Protocol identifier for the message
  * @tx_size: transmit message size
  * @rx_size: receive message size
  * @p: pointer to the allocated and initialised message
@@ -454,12 +535,14 @@ int scmi_do_xfer_with_response(const struct scmi_handle *handle,
  * Return: 0 if all went fine with @p pointing to message, else
  *	corresponding error.
  */
-int scmi_xfer_get_init(const struct scmi_handle *handle, u8 msg_id, u8 prot_id,
-		       size_t tx_size, size_t rx_size, struct scmi_xfer **p)
+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;
-	struct scmi_info *info = handle_to_scmi_info(handle);
+	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;
 
@@ -468,7 +551,7 @@ int scmi_xfer_get_init(const struct scmi_handle *handle, u8 msg_id, u8 prot_id,
 	    tx_size > info->desc->max_msg_size)
 		return -ERANGE;
 
-	xfer = scmi_xfer_get(handle, minfo);
+	xfer = scmi_xfer_get(pi->handle, minfo);
 	if (IS_ERR(xfer)) {
 		ret = PTR_ERR(xfer);
 		dev_err(dev, "failed to get free message slot(%d)\n", ret);
@@ -478,7 +561,7 @@ int scmi_xfer_get_init(const struct scmi_handle *handle, u8 msg_id, u8 prot_id,
 	xfer->tx.len = tx_size;
 	xfer->rx.len = rx_size ? : info->desc->max_msg_size;
 	xfer->hdr.id = msg_id;
-	xfer->hdr.protocol_id = prot_id;
+	xfer->hdr.protocol_id = pi->proto->id;
 	xfer->hdr.poll_completion = false;
 
 	*p = xfer;
@@ -487,43 +570,276 @@ int scmi_xfer_get_init(const struct scmi_handle *handle, u8 msg_id, u8 prot_id,
 }
 
 /**
- * scmi_version_get() - command to get the revision of the SCMI entity
+ * version_get() - command to get the revision of the SCMI entity
  *
- * @handle: Pointer to SCMI entity handle
- * @protocol: Protocol identifier for the message
+ * @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.
  */
-int scmi_version_get(const struct scmi_handle *handle, u8 protocol,
-		     u32 *version)
+static int version_get(const struct scmi_protocol_handle *ph, u32 *version)
 {
 	int ret;
 	__le32 *rev_info;
 	struct scmi_xfer *t;
 
-	ret = scmi_xfer_get_init(handle, PROTOCOL_VERSION, protocol, 0,
-				 sizeof(*version), &t);
+	ret = xfer_get_init(ph, PROTOCOL_VERSION, 0, sizeof(*version), &t);
 	if (ret)
 		return ret;
 
-	ret = scmi_do_xfer(handle, t);
+	ret = do_xfer(ph, t);
 	if (!ret) {
 		rev_info = t->rx.buf;
 		*version = le32_to_cpu(*rev_info);
 	}
 
-	scmi_xfer_put(handle, t);
+	xfer_put(ph, t);
 	return ret;
 }
 
-void scmi_setup_protocol_implemented(const struct scmi_handle *handle,
-				     u8 *prot_imp)
+/**
+ * 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,
+};
+
+/**
+ * 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.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;
 }
 
@@ -542,6 +858,102 @@ scmi_is_protocol_implemented(const struct scmi_handle *handle, u8 prot_id)
 	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);
+}
+
+/**
+ * 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;
+	struct scmi_protocol_devres *dres;
+	struct scmi_handle *handle = sdev->handle;
+
+	if (!ph)
+		return ERR_PTR(-EINVAL);
+
+	dres = devres_alloc(scmi_devm_release_protocol,
+			    sizeof(*dres), GFP_KERNEL);
+	if (!dres)
+		return ERR_PTR(-ENOMEM);
+
+	pi = scmi_get_protocol_instance(handle, protocol_id);
+	if (IS_ERR(pi)) {
+		devres_free(dres);
+		return pi;
+	}
+
+	dres->handle = handle;
+	dres->protocol_id = protocol_id;
+	devres_add(&sdev->dev, dres);
+
+	*ph = &pi->ph;
+
+	return pi->proto->ops;
+}
+
+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);
+}
+
+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
  *
@@ -563,8 +975,7 @@ struct scmi_handle *scmi_handle_get(struct device *dev)
 	list_for_each(p, &scmi_list) {
 		info = list_entry(p, struct scmi_info, node);
 		if (dev->parent == info->dev) {
-			handle = &info->handle;
-			info->users++;
+			handle = scmi_handle_get_from_info_unlocked(info);
 			break;
 		}
 	}
@@ -707,63 +1118,268 @@ scmi_txrx_setup(struct scmi_info *info, struct device *dev, int prot_id)
 	return ret;
 }
 
-static inline void
-scmi_create_protocol_device(struct device_node *np, struct scmi_info *info,
-			    int prot_id, const char *name)
+/**
+ * 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.
+ */
+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;
+
+	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);
-		return;
+		return NULL;
 	}
 
 	if (scmi_txrx_setup(info, &sdev->dev, prot_id)) {
 		dev_err(&sdev->dev, "failed to setup transport\n");
 		scmi_device_destroy(sdev);
-		return;
+		return NULL;
 	}
 
+	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);
 }
 
-#define MAX_SCMI_DEV_PER_PROTOCOL	2
-struct scmi_prot_devnames {
-	int protocol_id;
-	char *names[MAX_SCMI_DEV_PER_PROTOCOL];
-};
+/**
+ * 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;
 
-static struct scmi_prot_devnames devnames[] = {
-	{ SCMI_PROTOCOL_POWER,  { "genpd" },},
-	{ SCMI_PROTOCOL_SYSTEM, { "syspower" },},
-	{ SCMI_PROTOCOL_PERF,   { "cpufreq" },},
-	{ SCMI_PROTOCOL_CLOCK,  { "clocks" },},
-	{ SCMI_PROTOCOL_SENSOR, { "hwmon", "iiodev" },},
-	{ SCMI_PROTOCOL_RESET,  { "reset" },},
-	{ SCMI_PROTOCOL_VOLTAGE,  { "regulator" },},
-};
+	mutex_lock(&scmi_requested_devices_mtx);
+	phead = idr_find(&scmi_requested_devices, prot_id);
+	if (phead) {
+		struct scmi_requested_dev *rdev;
 
-static inline void
-scmi_create_protocol_devices(struct device_node *np, struct scmi_info *info,
-			     int prot_id)
+		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 loop, cnt;
+	int ret = 0;
+	unsigned int id = 0;
+	struct list_head *head, *phead = NULL;
+	struct scmi_requested_dev *rdev;
+	struct scmi_info *info;
 
-	for (loop = 0; loop < ARRAY_SIZE(devnames); loop++) {
-		if (devnames[loop].protocol_id != prot_id)
-			continue;
+	pr_debug("Requesting SCMI device (%s) for protocol %x\n",
+		 id_table->name, id_table->protocol_id);
 
-		for (cnt = 0; cnt < ARRAY_SIZE(devnames[loop].names); cnt++) {
-			const char *name = devnames[loop].names[cnt];
+	/*
+	 * 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;
 
-			if (name)
-				scmi_create_protocol_device(np, info, prot_id,
-							    name);
+	/*
+	 * 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);
+			/* Set handle if not already set: device existed */
+			if (sdev && !sdev->handle)
+				sdev->handle =
+					scmi_handle_get_from_info_unlocked(info);
+		} 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_probe(struct platform_device *pdev)
@@ -786,6 +1402,9 @@ static int scmi_probe(struct platform_device *pdev)
 	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);
@@ -794,6 +1413,8 @@ static int scmi_probe(struct platform_device *pdev)
 	handle = &info->handle;
 	handle->dev = info->dev;
 	handle->version = &info->version;
+	handle->devm_protocol_get = scmi_devm_protocol_get;
+	handle->devm_protocol_put = scmi_devm_protocol_put;
 
 	ret = scmi_txrx_setup(info, dev, SCMI_PROTOCOL_BASE);
 	if (ret)
@@ -806,9 +1427,14 @@ static int scmi_probe(struct platform_device *pdev)
 	if (scmi_notification_init(handle))
 		dev_err(dev, "SCMI Notifications NOT available.\n");
 
-	ret = scmi_base_protocol_init(handle);
+	/*
+	 * 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(%d)\n", ret);
+		dev_err(dev, "unable to communicate with SCMI\n");
 		return ret;
 	}
 
@@ -831,6 +1457,19 @@ static int scmi_probe(struct platform_device *pdev)
 			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);
 	}
 
@@ -844,9 +1483,10 @@ void scmi_free_channel(struct scmi_chan_info *cinfo, struct idr *idr, int id)
 
 static int scmi_remove(struct platform_device *pdev)
 {
-	int ret = 0;
+	int ret = 0, id;
 	struct scmi_info *info = platform_get_drvdata(pdev);
 	struct idr *idr = &info->tx_idr;
+	struct device_node *child;
 
 	mutex_lock(&scmi_list_mutex);
 	if (info->users)
@@ -860,6 +1500,14 @@ static int scmi_remove(struct platform_device *pdev)
 
 	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 = idr_for_each(idr, info->desc->ops->chan_free, idr);
 	idr_destroy(&info->tx_idr);
@@ -942,6 +1590,8 @@ static int __init scmi_driver_init(void)
 {
 	scmi_bus_init();
 
+	scmi_base_register();
+
 	scmi_clock_register();
 	scmi_perf_register();
 	scmi_power_register();
@@ -956,7 +1606,7 @@ subsys_initcall(scmi_driver_init);
 
 static void __exit scmi_driver_exit(void)
 {
-	scmi_bus_exit();
+	scmi_base_unregister();
 
 	scmi_clock_unregister();
 	scmi_perf_unregister();
@@ -966,6 +1616,8 @@ static void __exit scmi_driver_exit(void)
 	scmi_voltage_unregister();
 	scmi_system_unregister();
 
+	scmi_bus_exit();
+
 	platform_driver_unregister(&scmi_driver);
 }
 module_exit(scmi_driver_exit);