Merge tag 'scmi-updates-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into arm/drivers

ARM SCMI updates/fixes for v5.4

Handful of fixes/updates including:
1. SCMI v2.0(recently released) support for:
	- Performance protocol fast channels
	- Reset Management Protocol
2. SCMI infrastructure/core support for recieve(Rx) channels,
   asynchronous commands and delayed response
3. Usage of asynchronous commands for clock rate setting and sensor
   reading based on the attributes read from the firmware
4. Miscellaneous cleanups(typos, naming alignment with specification,
   and SPDX License identifier)
5. Couple of fixes: removal of extra check for invalid length and
   additional check to ensure platform/firmware has released shared
   memory before using it in OSPM

* tag 'scmi-updates-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux: (22 commits)
  reset: Add support for resets provided by SCMI
  firmware: arm_scmi: Add RESET protocol in SCMI v2.0
  dt-bindings: arm: Extend SCMI to support new reset protocol
  firmware: arm_scmi: Make use SCMI v2.0 fastchannel for performance protocol
  firmware: arm_scmi: Add discovery of SCMI v2.0 performance fastchannels
  firmware: arm_scmi: Use {get,put}_unaligned_le{32,64} accessors
  firmware: arm_scmi: Use asynchronous CLOCK_RATE_SET when possible
  firmware: arm_scmi: Drop config flag in clk_ops->rate_set
  firmware: arm_scmi: Add asynchronous sensor read if it supports
  firmware: arm_scmi: Drop async flag in sensor_ops->reading_get
  firmware: arm_scmi: Add support for asynchronous commands and delayed response
  firmware: arm_scmi: Add mechanism to unpack message headers
  firmware: arm_scmi: Separate out tx buffer handling and prepare to add rx
  firmware: arm_scmi: Add receive channel support for notifications
  firmware: arm_scmi: Segregate tx channel handling and prepare to add rx
  firmware: arm_scmi: Reorder some functions to avoid forward declarations
  firmware: arm_scmi: Check if platform has released shmem before using
  firmware: arm_scmi: Use the term 'message' instead of 'command'
  firmware: arm_scmi: Fix few trivial typos in comments
  firmware: arm_scmi: Remove extra check for invalid length message responses
  ...

Link: https://lore.kernel.org/r/20190814172454.26191-1-sudeep.holla@arm.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

17 files changed, 981 insertions, 202 deletions

diff --git a/Documentation/devicetree/bindings/arm/arm,scmi.txt b/Documentation/devicetree/bindings/arm/arm,scmi.txt
index 317a2fc3667a..083dbf96ee00 100644
--- a/Documentation/devicetree/bindings/arm/arm,scmi.txt
+++ b/Documentation/devicetree/bindings/arm/arm,scmi.txt
@@ -73,6 +73,16 @@ Required properties:
 			 as used by the firmware. Refer to  platform details
 			 for your implementation for the IDs to use.
 
+Reset signal bindings for the reset domains based on SCMI Message Protocol
+------------------------------------------------------------
+
+This binding for the SCMI reset domain providers uses the generic reset
+signal binding[5].
+
+Required properties:
+ - #reset-cells : Should be 1. Contains the reset domain ID value used
+		  by SCMI commands.
+
 SRAM and Shared Memory for SCMI
 -------------------------------
 
@@ -93,6 +103,7 @@ Required sub-node properties:
 [2] Documentation/devicetree/bindings/power/power_domain.txt
 [3] Documentation/devicetree/bindings/thermal/thermal.txt
 [4] Documentation/devicetree/bindings/sram/sram.txt
+[5] Documentation/devicetree/bindings/reset/reset.txt
 
 Example:
 
@@ -152,6 +163,11 @@ firmware {
 			reg = <0x15>;
 			#thermal-sensor-cells = <1>;
 		};
+
+		scmi_reset: protocol@16 {
+			reg = <0x16>;
+			#reset-cells = <1>;
+		};
 	};
 };
 
@@ -166,6 +182,7 @@ hdlcd@7ff60000 {
 	reg = <0 0x7ff60000 0 0x1000>;
 	clocks = <&scmi_clk 4>;
 	power-domains = <&scmi_devpd 1>;
+	resets = <&scmi_reset 10>;
 };
 
 thermal-zones {
diff --git a/MAINTAINERS b/MAINTAINERS
index 0872e4cb98ef..bd95faf18f40 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15557,6 +15557,7 @@ F:	drivers/clk/clk-sc[mp]i.c
 F:	drivers/cpufreq/sc[mp]i-cpufreq.c
 F:	drivers/firmware/arm_scpi.c
 F:	drivers/firmware/arm_scmi/
+F:	drivers/reset/reset-scmi.c
 F:	include/linux/sc[mp]i_protocol.h
 
 SYSTEM RESET/SHUTDOWN DRIVERS
diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
index a2287c770d5c..886f7c5df51a 100644
--- a/drivers/clk/clk-scmi.c
+++ b/drivers/clk/clk-scmi.c
@@ -69,7 +69,7 @@ static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 {
 	struct scmi_clk *clk = to_scmi_clk(hw);
 
-	return clk->handle->clk_ops->rate_set(clk->handle, clk->id, 0, rate);
+	return clk->handle->clk_ops->rate_set(clk->handle, clk->id, rate);
 }
 
 static int scmi_clk_enable(struct clk_hw *hw)
diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
index c47d28d556b6..5f298f00a82e 100644
--- a/drivers/firmware/arm_scmi/Makefile
+++ b/drivers/firmware/arm_scmi/Makefile
@@ -2,5 +2,5 @@
 obj-y	= scmi-bus.o scmi-driver.o scmi-protocols.o
 scmi-bus-y = bus.o
 scmi-driver-y = driver.o
-scmi-protocols-y = base.o clock.o perf.o power.o sensors.o
+scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o
 obj-$(CONFIG_ARM_SCMI_POWER_DOMAIN) += scmi_pm_domain.o
diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c
index 204390297f4b..f804e8af6521 100644
--- a/drivers/firmware/arm_scmi/base.c
+++ b/drivers/firmware/arm_scmi/base.c
@@ -204,7 +204,7 @@ static int scmi_base_discover_agent_get(const struct scmi_handle *handle,
 	if (ret)
 		return ret;
 
-	*(__le32 *)t->tx.buf = cpu_to_le32(id);
+	put_unaligned_le32(id, t->tx.buf);
 
 	ret = scmi_do_xfer(handle, t);
 	if (!ret)
diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
index 0a194af92438..32526a793f3a 100644
--- a/drivers/firmware/arm_scmi/clock.c
+++ b/drivers/firmware/arm_scmi/clock.c
@@ -56,7 +56,7 @@ struct scmi_msg_resp_clock_describe_rates {
 struct scmi_clock_set_rate {
 	__le32 flags;
 #define CLOCK_SET_ASYNC		BIT(0)
-#define CLOCK_SET_DELAYED	BIT(1)
+#define CLOCK_SET_IGNORE_RESP	BIT(1)
 #define CLOCK_SET_ROUND_UP	BIT(2)
 #define CLOCK_SET_ROUND_AUTO	BIT(3)
 	__le32 id;
@@ -67,6 +67,7 @@ struct scmi_clock_set_rate {
 struct clock_info {
 	int num_clocks;
 	int max_async_req;
+	atomic_t cur_async_req;
 	struct scmi_clock_info *clk;
 };
 
@@ -106,7 +107,7 @@ static int scmi_clock_attributes_get(const struct scmi_handle *handle,
 	if (ret)
 		return ret;
 
-	*(__le32 *)t->tx.buf = cpu_to_le32(clk_id);
+	put_unaligned_le32(clk_id, t->tx.buf);
 	attr = t->rx.buf;
 
 	ret = scmi_do_xfer(handle, t);
@@ -203,39 +204,47 @@ scmi_clock_rate_get(const struct scmi_handle *handle, u32 clk_id, u64 *value)
 	if (ret)
 		return ret;
 
-	*(__le32 *)t->tx.buf = cpu_to_le32(clk_id);
+	put_unaligned_le32(clk_id, t->tx.buf);
 
 	ret = scmi_do_xfer(handle, t);
-	if (!ret) {
-		__le32 *pval = t->rx.buf;
-
-		*value = le32_to_cpu(*pval);
-		*value |= (u64)le32_to_cpu(*(pval + 1)) << 32;
-	}
+	if (!ret)
+		*value = get_unaligned_le64(t->rx.buf);
 
 	scmi_xfer_put(handle, t);
 	return ret;
 }
 
 static int scmi_clock_rate_set(const struct scmi_handle *handle, u32 clk_id,
-			       u32 config, u64 rate)
+			       u64 rate)
 {
 	int ret;
+	u32 flags = 0;
 	struct scmi_xfer *t;
 	struct scmi_clock_set_rate *cfg;
+	struct clock_info *ci = handle->clk_priv;
 
 	ret = scmi_xfer_get_init(handle, CLOCK_RATE_SET, SCMI_PROTOCOL_CLOCK,
 				 sizeof(*cfg), 0, &t);
 	if (ret)
 		return ret;
 
+	if (ci->max_async_req &&
+	    atomic_inc_return(&ci->cur_async_req) < ci->max_async_req)
+		flags |= CLOCK_SET_ASYNC;
+
 	cfg = t->tx.buf;
-	cfg->flags = cpu_to_le32(config);
+	cfg->flags = cpu_to_le32(flags);
 	cfg->id = cpu_to_le32(clk_id);
 	cfg->value_low = cpu_to_le32(rate & 0xffffffff);
 	cfg->value_high = cpu_to_le32(rate >> 32);
 
-	ret = scmi_do_xfer(handle, t);
+	if (flags & CLOCK_SET_ASYNC)
+		ret = scmi_do_xfer_with_response(handle, t);
+	else
+		ret = scmi_do_xfer(handle, t);
+
+	if (ci->max_async_req)
+		atomic_dec(&ci->cur_async_req);
 
 	scmi_xfer_put(handle, t);
 	return ret;
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index 44fd4f9404a9..5237c2ff79fe 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -15,6 +15,8 @@
 #include <linux/scmi_protocol.h>
 #include <linux/types.h>
 
+#include <asm/unaligned.h>
+
 #define PROTOCOL_REV_MINOR_MASK	GENMASK(15, 0)
 #define PROTOCOL_REV_MAJOR_MASK	GENMASK(31, 16)
 #define PROTOCOL_REV_MAJOR(x)	(u16)(FIELD_GET(PROTOCOL_REV_MAJOR_MASK, (x)))
@@ -48,11 +50,11 @@ struct scmi_msg_resp_prot_version {
 /**
  * struct scmi_msg_hdr - Message(Tx/Rx) header
  *
- * @id: The identifier of the command being sent
- * @protocol_id: The identifier of the protocol used to send @id command
- * @seq: The token to identify the message. when a message/command returns,
- *	the platform returns the whole message header unmodified including
- *	the token
+ * @id: The identifier of the message being sent
+ * @protocol_id: The identifier of the protocol used to send @id message
+ * @seq: The token to identify the message. When a message returns, the
+ *	platform returns the whole message header unmodified including the
+ *	token
  * @status: Status of the transfer once it's complete
  * @poll_completion: Indicate if the transfer needs to be polled for
  *	completion or interrupt mode is used
@@ -84,17 +86,21 @@ struct scmi_msg {
  * @rx: Receive message, the buffer should be pre-allocated to store
  *	message. If request-ACK protocol is used, we can reuse the same
  *	buffer for the rx path as we use for the tx path.
- * @done: completion event
+ * @done: command message transmit completion event
+ * @async: pointer to delayed response message received event completion
  */
 struct scmi_xfer {
 	struct scmi_msg_hdr hdr;
 	struct scmi_msg tx;
 	struct scmi_msg rx;
 	struct completion done;
+	struct completion *async_done;
 };
 
 void scmi_xfer_put(const struct scmi_handle *h, struct scmi_xfer *xfer);
 int scmi_do_xfer(const struct scmi_handle *h, struct scmi_xfer *xfer);
+int scmi_do_xfer_with_response(const struct scmi_handle *h,
+			       struct scmi_xfer *xfer);
 int scmi_xfer_get_init(const struct scmi_handle *h, u8 msg_id, u8 prot_id,
 		       size_t tx_size, size_t rx_size, struct scmi_xfer **p);
 int scmi_handle_put(const struct scmi_handle *handle);
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index b5bc4c7a8fab..3eb0382491ce 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -30,8 +30,14 @@
 #include "common.h"
 
 #define MSG_ID_MASK		GENMASK(7, 0)
+#define MSG_XTRACT_ID(hdr)	FIELD_GET(MSG_ID_MASK, (hdr))
 #define MSG_TYPE_MASK		GENMASK(9, 8)
+#define MSG_XTRACT_TYPE(hdr)	FIELD_GET(MSG_TYPE_MASK, (hdr))
+#define MSG_TYPE_COMMAND	0
+#define MSG_TYPE_DELAYED_RESP	2
+#define MSG_TYPE_NOTIFICATION	3
 #define MSG_PROTOCOL_ID_MASK	GENMASK(17, 10)
+#define MSG_XTRACT_PROT_ID(hdr)	FIELD_GET(MSG_PROTOCOL_ID_MASK, (hdr))
 #define MSG_TOKEN_ID_MASK	GENMASK(27, 18)
 #define MSG_XTRACT_TOKEN(hdr)	FIELD_GET(MSG_TOKEN_ID_MASK, (hdr))
 #define MSG_TOKEN_MAX		(MSG_XTRACT_TOKEN(MSG_TOKEN_ID_MASK) + 1)
@@ -86,7 +92,7 @@ struct scmi_desc {
 };
 
 /**
- * struct scmi_chan_info - Structure representing a SCMI channel informfation
+ * struct scmi_chan_info - Structure representing a SCMI channel information
  *
  * @cl: Mailbox Client
  * @chan: Transmit/Receive mailbox channel
@@ -111,8 +117,9 @@ struct scmi_chan_info {
  * @handle: Instance of SCMI handle to send to clients
  * @version: SCMI revision information containing protocol version,
  *	implementation version and (sub-)vendor identification.
- * @minfo: Message info
- * @tx_idr: IDR object to map protocol id to channel info pointer
+ * @tx_minfo: Universal Transmit 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_imp: List of protocols implemented, currently maximum of
  *	MAX_PROTOCOLS_IMP elements allocated by the base protocol
  * @node: List head
@@ -123,8 +130,9 @@ struct scmi_info {
 	const struct scmi_desc *desc;
 	struct scmi_revision_info version;
 	struct scmi_handle handle;
-	struct scmi_xfers_info minfo;
+	struct scmi_xfers_info tx_minfo;
 	struct idr tx_idr;
+	struct idr rx_idr;
 	u8 *protocols_imp;
 	struct list_head node;
 	int users;
@@ -182,7 +190,7 @@ static inline int scmi_to_linux_errno(int errno)
 static inline void scmi_dump_header_dbg(struct device *dev,
 					struct scmi_msg_hdr *hdr)
 {
-	dev_dbg(dev, "Command ID: %x Sequence ID: %x Protocol: %x\n",
+	dev_dbg(dev, "Message ID: %x Sequence ID: %x Protocol: %x\n",
 		hdr->id, hdr->seq, hdr->protocol_id);
 }
 
@@ -190,7 +198,7 @@ static void scmi_fetch_response(struct scmi_xfer *xfer,
 				struct scmi_shared_mem __iomem *mem)
 {
 	xfer->hdr.status = ioread32(mem->msg_payload);
-	/* Skip the length of header and statues in payload area i.e 8 bytes*/
+	/* Skip the length of header and status in payload area i.e 8 bytes */
 	xfer->rx.len = min_t(size_t, xfer->rx.len, ioread32(&mem->length) - 8);
 
 	/* Take a copy to the rx buffer.. */
@@ -198,56 +206,12 @@ static void scmi_fetch_response(struct scmi_xfer *xfer,
 }
 
 /**
- * scmi_rx_callback() - mailbox client callback for receive messages
- *
- * @cl: client pointer
- * @m: mailbox message
- *
- * 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.
- */
-static void scmi_rx_callback(struct mbox_client *cl, void *m)
-{
-	u16 xfer_id;
-	struct scmi_xfer *xfer;
-	struct scmi_chan_info *cinfo = client_to_scmi_chan_info(cl);
-	struct device *dev = cinfo->dev;
-	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
-	struct scmi_xfers_info *minfo = &info->minfo;
-	struct scmi_shared_mem __iomem *mem = cinfo->payload;
-
-	xfer_id = MSG_XTRACT_TOKEN(ioread32(&mem->msg_header));
-
-	/* Are we even expecting this? */
-	if (!test_bit(xfer_id, minfo->xfer_alloc_table)) {
-		dev_err(dev, "message for %d is not expected!\n", xfer_id);
-		return;
-	}
-
-	xfer = &minfo->xfer_block[xfer_id];
-
-	scmi_dump_header_dbg(dev, &xfer->hdr);
-	/* Is the message of valid length? */
-	if (xfer->rx.len > info->desc->max_msg_size) {
-		dev_err(dev, "unable to handle %zu xfer(max %d)\n",
-			xfer->rx.len, info->desc->max_msg_size);
-		return;
-	}
-
-	scmi_fetch_response(xfer, mem);
-	complete(&xfer->done);
-}
-
-/**
  * pack_scmi_header() - packs and returns 32-bit header
  *
  * @hdr: pointer to header containing all the information on message id,
  *	protocol id and sequence id.
  *
- * Return: 32-bit packed command header to be sent to the platform.
+ * Return: 32-bit packed message header to be sent to the platform.
  */
 static inline u32 pack_scmi_header(struct scmi_msg_hdr *hdr)
 {
@@ -257,6 +221,18 @@ static inline u32 pack_scmi_header(struct scmi_msg_hdr *hdr)
 }
 
 /**
+ * unpack_scmi_header() - unpacks and records message and protocol id
+ *
+ * @msg_hdr: 32-bit packed message header sent from the platform
+ * @hdr: pointer to header to fetch message and protocol id.
+ */
+static inline void unpack_scmi_header(u32 msg_hdr, struct scmi_msg_hdr *hdr)
+{
+	hdr->id = MSG_XTRACT_ID(msg_hdr);
+	hdr->protocol_id = MSG_XTRACT_PROT_ID(msg_hdr);
+}
+
+/**
  * scmi_tx_prepare() - mailbox client callback to prepare for the transfer
  *
  * @cl: client pointer
@@ -271,6 +247,14 @@ static void scmi_tx_prepare(struct mbox_client *cl, void *m)
 	struct scmi_chan_info *cinfo = client_to_scmi_chan_info(cl);
 	struct scmi_shared_mem __iomem *mem = cinfo->payload;
 
+	/*
+	 * Ideally channel must be free by now unless OS timeout last
+	 * request and platform continued to process the same, wait
+	 * until it releases the shared memory, otherwise we may endup
+	 * overwriting its response with new message payload or vice-versa
+	 */
+	spin_until_cond(ioread32(&mem->channel_status) &
+			SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
 	/* Mark channel busy + clear error */
 	iowrite32(0x0, &mem->channel_status);
 	iowrite32(t->hdr.poll_completion ? 0 : SCMI_SHMEM_FLAG_INTR_ENABLED,
@@ -285,8 +269,9 @@ static void scmi_tx_prepare(struct mbox_client *cl, void *m)
  * scmi_xfer_get() - Allocate one message
  *
  * @handle: Pointer to SCMI entity handle
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
  *
- * Helper function which is used by various command functions that are
+ * Helper function which is used by various message functions that are
  * exposed to clients of this driver for allocating a message traffic event.
  *
  * This function can sleep depending on pending requests already in the system
@@ -295,13 +280,13 @@ static void scmi_tx_prepare(struct mbox_client *cl, void *m)
  *
  * Return: 0 if all went fine, else corresponding error.
  */
-static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle)
+static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle,
+				       struct scmi_xfers_info *minfo)
 {
 	u16 xfer_id;
 	struct scmi_xfer *xfer;
 	unsigned long flags, bit_pos;
 	struct scmi_info *info = handle_to_scmi_info(handle);
-	struct scmi_xfers_info *minfo = &info->minfo;
 
 	/* Keep the locked section as small as possible */
 	spin_lock_irqsave(&minfo->xfer_lock, flags);
@@ -324,18 +309,17 @@ static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle)
 }
 
 /**
- * scmi_xfer_put() - Release a message
+ * __scmi_xfer_put() - Release a message
  *
- * @handle: Pointer to SCMI entity handle
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
  * @xfer: message that was reserved by scmi_xfer_get
  *
  * This holds a spinlock to maintain integrity of internal data structures.
  */
-void scmi_xfer_put(const struct scmi_handle *handle, struct scmi_xfer *xfer)
+static void
+__scmi_xfer_put(struct scmi_xfers_info *minfo, struct scmi_xfer *xfer)
 {
 	unsigned long flags;
-	struct scmi_info *info = handle_to_scmi_info(handle);
-	struct scmi_xfers_info *minfo = &info->minfo;
 
 	/*
 	 * Keep the locked section as small as possible
@@ -347,6 +331,68 @@ void scmi_xfer_put(const struct scmi_handle *handle, struct scmi_xfer *xfer)
 	spin_unlock_irqrestore(&minfo->xfer_lock, flags);
 }
 
+/**
+ * scmi_rx_callback() - mailbox client callback for receive messages
+ *
+ * @cl: client pointer
+ * @m: mailbox message
+ *
+ * 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.
+ */
+static void scmi_rx_callback(struct mbox_client *cl, void *m)
+{
+	u8 msg_type;
+	u32 msg_hdr;
+	u16 xfer_id;
+	struct scmi_xfer *xfer;
+	struct scmi_chan_info *cinfo = client_to_scmi_chan_info(cl);
+	struct device *dev = cinfo->dev;
+	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+	struct scmi_xfers_info *minfo = &info->tx_minfo;
+	struct scmi_shared_mem __iomem *mem = cinfo->payload;
+
+	msg_hdr = ioread32(&mem->msg_header);
+	msg_type = MSG_XTRACT_TYPE(msg_hdr);
+	xfer_id = MSG_XTRACT_TOKEN(msg_hdr);
+
+	if (msg_type == MSG_TYPE_NOTIFICATION)
+		return; /* Notifications not yet supported */
+
+	/* Are we even expecting this? */
+	if (!test_bit(xfer_id, minfo->xfer_alloc_table)) {
+		dev_err(dev, "message for %d is not expected!\n", xfer_id);
+		return;
+	}
+
+	xfer = &minfo->xfer_block[xfer_id];
+
+	scmi_dump_header_dbg(dev, &xfer->hdr);
+
+	scmi_fetch_response(xfer, mem);
+
+	if (msg_type == MSG_TYPE_DELAYED_RESP)
+		complete(xfer->async_done);
+	else
+		complete(&xfer->done);
+}
+
+/**
+ * scmi_xfer_put() - Release a transmit message
+ *
+ * @handle: Pointer to SCMI entity handle
+ * @xfer: message that was reserved by scmi_xfer_get
+ */
+void scmi_xfer_put(const struct scmi_handle *handle, struct scmi_xfer *xfer)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	__scmi_xfer_put(&info->tx_minfo, xfer);
+}
+
 static bool
 scmi_xfer_poll_done(const struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
 {
@@ -435,8 +481,36 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer)
 	return ret;
 }
 
+#define SCMI_MAX_RESPONSE_TIMEOUT	(2 * MSEC_PER_SEC)
+
+/**
+ * scmi_do_xfer_with_response() - Do one transfer and wait until the delayed
+ *	response is received
+ *
+ * @handle: Pointer to SCMI entity 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)
+{
+	int ret, timeout = msecs_to_jiffies(SCMI_MAX_RESPONSE_TIMEOUT);
+	DECLARE_COMPLETION_ONSTACK(async_response);
+
+	xfer->async_done = &async_response;
+
+	ret = scmi_do_xfer(handle, xfer);
+	if (!ret && !wait_for_completion_timeout(xfer->async_done, timeout))
+		ret = -ETIMEDOUT;
+
+	xfer->async_done = NULL;
+	return ret;
+}
+
 /**
- * scmi_xfer_get_init() - Allocate and initialise one message
+ * scmi_xfer_get_init() - Allocate and initialise one message for transmit
  *
  * @handle: Pointer to SCMI entity handle
  * @msg_id: Message identifier
@@ -457,6 +531,7 @@ int scmi_xfer_get_init(const struct scmi_handle *handle, u8 msg_id, u8 prot_id,
 	int ret;
 	struct scmi_xfer *xfer;
 	struct scmi_info *info = handle_to_scmi_info(handle);
+	struct scmi_xfers_info *minfo = &info->tx_minfo;
 	struct device *dev = info->dev;
 
 	/* Ensure we have sane transfer sizes */
@@ -464,7 +539,7 @@ 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);
+	xfer = scmi_xfer_get(handle, minfo);
 	if (IS_ERR(xfer)) {
 		ret = PTR_ERR(xfer);
 		dev_err(dev, "failed to get free message slot(%d)\n", ret);
@@ -597,27 +672,13 @@ int scmi_handle_put(const struct scmi_handle *handle)
 	return 0;
 }
 
-static const struct scmi_desc scmi_generic_desc = {
-	.max_rx_timeout_ms = 30,	/* We may increase this if required */
-	.max_msg = 20,		/* Limited by MBOX_TX_QUEUE_LEN */
-	.max_msg_size = 128,
-};
-
-/* Each compatible listed below must have descriptor associated with it */
-static const struct of_device_id scmi_of_match[] = {
-	{ .compatible = "arm,scmi", .data = &scmi_generic_desc },
-	{ /* Sentinel */ },
-};
-
-MODULE_DEVICE_TABLE(of, scmi_of_match);
-
 static int scmi_xfer_info_init(struct scmi_info *sinfo)
 {
 	int i;
 	struct scmi_xfer *xfer;
 	struct device *dev = sinfo->dev;
 	const struct scmi_desc *desc = sinfo->desc;
-	struct scmi_xfers_info *info = &sinfo->minfo;
+	struct scmi_xfers_info *info = &sinfo->tx_minfo;
 
 	/* Pre-allocated messages, no more than what hdr.seq can support */
 	if (WARN_ON(desc->max_msg >= MSG_TOKEN_MAX)) {
@@ -652,61 +713,32 @@ static int scmi_xfer_info_init(struct scmi_info *sinfo)
 	return 0;
 }
 
-static int scmi_mailbox_check(struct device_node *np)
+static int scmi_mailbox_check(struct device_node *np, int idx)
 {
-	return of_parse_phandle_with_args(np, "mboxes", "#mbox-cells", 0, NULL);
+	return of_parse_phandle_with_args(np, "mboxes", "#mbox-cells",
+					  idx, NULL);
 }
 
-static int scmi_mbox_free_channel(int id, void *p, void *data)
+static int scmi_mbox_chan_setup(struct scmi_info *info, struct device *dev,
+				int prot_id, bool tx)
 {
-	struct scmi_chan_info *cinfo = p;
-	struct idr *idr = data;
-
-	if (!IS_ERR_OR_NULL(cinfo->chan)) {
-		mbox_free_channel(cinfo->chan);
-		cinfo->chan = NULL;
-	}
-
-	idr_remove(idr, id);
-
-	return 0;
-}
-
-static int scmi_remove(struct platform_device *pdev)
-{
-	int ret = 0;
-	struct scmi_info *info = platform_get_drvdata(pdev);
-	struct idr *idr = &info->tx_idr;
-
-	mutex_lock(&scmi_list_mutex);
-	if (info->users)
-		ret = -EBUSY;
-	else
-		list_del(&info->node);
-	mutex_unlock(&scmi_list_mutex);
-
-	if (ret)
-		return ret;
-
-	/* Safe to free channels since no more users */
-	ret = idr_for_each(idr, scmi_mbox_free_channel, idr);
-	idr_destroy(&info->tx_idr);
-
-	return ret;
-}
-
-static inline int
-scmi_mbox_chan_setup(struct scmi_info *info, struct device *dev, int prot_id)
-{
-	int ret;
+	int ret, idx;
 	struct resource res;
 	resource_size_t size;
 	struct device_node *shmem, *np = dev->of_node;
 	struct scmi_chan_info *cinfo;
 	struct mbox_client *cl;
+	struct idr *idr;
+	const char *desc = tx ? "Tx" : "Rx";
 
-	if (scmi_mailbox_check(np)) {
-		cinfo = idr_find(&info->tx_idr, SCMI_PROTOCOL_BASE);
+	/* Transmit channel is first entry i.e. index 0 */
+	idx = tx ? 0 : 1;
+	idr = tx ? &info->tx_idr : &info->rx_idr;
+
+	if (scmi_mailbox_check(np, idx)) {
+		cinfo = idr_find(idr, SCMI_PROTOCOL_BASE);
+		if (unlikely(!cinfo)) /* Possible only if platform has no Rx */
+			return -EINVAL;
 		goto idr_alloc;
 	}
 
@@ -719,36 +751,36 @@ scmi_mbox_chan_setup(struct scmi_info *info, struct device *dev, int prot_id)
 	cl = &cinfo->cl;
 	cl->dev = dev;
 	cl->rx_callback = scmi_rx_callback;
-	cl->tx_prepare = scmi_tx_prepare;
+	cl->tx_prepare = tx ? scmi_tx_prepare : NULL;
 	cl->tx_block = false;
-	cl->knows_txdone = true;
+	cl->knows_txdone = tx;
 
-	shmem = of_parse_phandle(np, "shmem", 0);
+	shmem = of_parse_phandle(np, "shmem", idx);
 	ret = of_address_to_resource(shmem, 0, &res);
 	of_node_put(shmem);
 	if (ret) {
-		dev_err(dev, "failed to get SCMI Tx payload mem resource\n");
+		dev_err(dev, "failed to get SCMI %s payload memory\n", desc);
 		return ret;
 	}
 
 	size = resource_size(&res);
 	cinfo->payload = devm_ioremap(info->dev, res.start, size);
 	if (!cinfo->payload) {
-		dev_err(dev, "failed to ioremap SCMI Tx payload\n");
+		dev_err(dev, "failed to ioremap SCMI %s payload\n", desc);
 		return -EADDRNOTAVAIL;
 	}
 
-	/* Transmit channel is first entry i.e. index 0 */
-	cinfo->chan = mbox_request_channel(cl, 0);
+	cinfo->chan = mbox_request_channel(cl, idx);
 	if (IS_ERR(cinfo->chan)) {
 		ret = PTR_ERR(cinfo->chan);
 		if (ret != -EPROBE_DEFER)
-			dev_err(dev, "failed to request SCMI Tx mailbox\n");
+			dev_err(dev, "failed to request SCMI %s mailbox\n",
+				desc);
 		return ret;
 	}
 
 idr_alloc:
-	ret = idr_alloc(&info->tx_idr, cinfo, prot_id, prot_id + 1, GFP_KERNEL);
+	ret = idr_alloc(idr, cinfo, prot_id, prot_id + 1, GFP_KERNEL);
 	if (ret != prot_id) {
 		dev_err(dev, "unable to allocate SCMI idr slot err %d\n", ret);
 		return ret;
@@ -758,6 +790,17 @@ idr_alloc:
 	return 0;
 }
 
+static inline int
+scmi_mbox_txrx_setup(struct scmi_info *info, struct device *dev, int prot_id)
+{
+	int ret = scmi_mbox_chan_setup(info, dev, prot_id, true);
+
+	if (!ret) /* Rx is optional, hence no error check */
+		scmi_mbox_chan_setup(info, dev, prot_id, false);
+
+	return ret;
+}
+
 static inline void
 scmi_create_protocol_device(struct device_node *np, struct scmi_info *info,
 			    int prot_id)
@@ -771,7 +814,7 @@ scmi_create_protocol_device(struct device_node *np, struct scmi_info *info,
 		return;
 	}
 
-	if (scmi_mbox_chan_setup(info, &sdev->dev, prot_id)) {
+	if (scmi_mbox_txrx_setup(info, &sdev->dev, prot_id)) {
 		dev_err(&sdev->dev, "failed to setup transport\n");
 		scmi_device_destroy(sdev);
 		return;
@@ -791,7 +834,7 @@ static int scmi_probe(struct platform_device *pdev)
 	struct device_node *child, *np = dev->of_node;
 
 	/* Only mailbox method supported, check for the presence of one */
-	if (scmi_mailbox_check(np)) {
+	if (scmi_mailbox_check(np, 0)) {
 		dev_err(dev, "no mailbox found in %pOF\n", np);
 		return -EINVAL;
 	}
@@ -814,12 +857,13 @@ static int scmi_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, info);
 	idr_init(&info->tx_idr);
+	idr_init(&info->rx_idr);
 
 	handle = &info->handle;
 	handle->dev = info->dev;
 	handle->version = &info->version;
 
-	ret = scmi_mbox_chan_setup(info, dev, SCMI_PROTOCOL_BASE);
+	ret = scmi_mbox_txrx_setup(info, dev, SCMI_PROTOCOL_BASE);
 	if (ret)
 		return ret;
 
@@ -854,6 +898,62 @@ static int scmi_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static int scmi_mbox_free_channel(int id, void *p, void *data)
+{
+	struct scmi_chan_info *cinfo = p;
+	struct idr *idr = data;
+
+	if (!IS_ERR_OR_NULL(cinfo->chan)) {
+		mbox_free_channel(cinfo->chan);
+		cinfo->chan = NULL;
+	}
+
+	idr_remove(idr, id);
+
+	return 0;
+}
+
+static int scmi_remove(struct platform_device *pdev)
+{
+	int ret = 0;
+	struct scmi_info *info = platform_get_drvdata(pdev);
+	struct idr *idr = &info->tx_idr;
+
+	mutex_lock(&scmi_list_mutex);
+	if (info->users)
+		ret = -EBUSY;
+	else
+		list_del(&info->node);
+	mutex_unlock(&scmi_list_mutex);
+
+	if (ret)
+		return ret;
+
+	/* Safe to free channels since no more users */
+	ret = idr_for_each(idr, scmi_mbox_free_channel, idr);
+	idr_destroy(&info->tx_idr);
+
+	idr = &info->rx_idr;
+	ret = idr_for_each(idr, scmi_mbox_free_channel, idr);
+	idr_destroy(&info->rx_idr);
+
+	return ret;
+}
+
+static const struct scmi_desc scmi_generic_desc = {
+	.max_rx_timeout_ms = 30,	/* We may increase this if required */
+	.max_msg = 20,		/* Limited by MBOX_TX_QUEUE_LEN */
+	.max_msg_size = 128,
+};
+
+/* Each compatible listed below must have descriptor associated with it */
+static const struct of_device_id scmi_of_match[] = {
+	{ .compatible = "arm,scmi", .data = &scmi_generic_desc },
+	{ /* Sentinel */ },
+};
+
+MODULE_DEVICE_TABLE(of, scmi_of_match);
+
 static struct platform_driver scmi_driver = {
 	.driver = {
 		   .name = "arm-scmi",
diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
index 3c8ae7cc35de..4a8012e3cb8c 100644
--- a/drivers/firmware/arm_scmi/perf.c
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -5,7 +5,10 @@
  * Copyright (C) 2018 ARM Ltd.
  */
 
+#include <linux/bits.h>
 #include <linux/of.h>
+#include <linux/io.h>
+#include <linux/io-64-nonatomic-hi-lo.h>
 #include <linux/platform_device.h>
 #include <linux/pm_opp.h>
 #include <linux/sort.h>
@@ -21,6 +24,7 @@ enum scmi_performance_protocol_cmd {
 	PERF_LEVEL_GET = 0x8,
 	PERF_NOTIFY_LIMITS = 0x9,
 	PERF_NOTIFY_LEVEL = 0xa,
+	PERF_DESCRIBE_FASTCHANNEL = 0xb,
 };
 
 struct scmi_opp {
@@ -44,6 +48,7 @@ struct scmi_msg_resp_perf_domain_attributes {
 #define SUPPORTS_SET_PERF_LVL(x)	((x) & BIT(30))
 #define SUPPORTS_PERF_LIMIT_NOTIFY(x)	((x) & BIT(29))
 #define SUPPORTS_PERF_LEVEL_NOTIFY(x)	((x) & BIT(28))
+#define SUPPORTS_PERF_FASTCHANNELS(x)	((x) & BIT(27))
 	__le32 rate_limit_us;
 	__le32 sustained_freq_khz;
 	__le32 sustained_perf_level;
@@ -87,17 +92,56 @@ struct scmi_msg_resp_perf_describe_levels {
 	} opp[0];
 };
 
+struct scmi_perf_get_fc_info {
+	__le32 domain;
+	__le32 message_id;
+};
+
+struct scmi_msg_resp_perf_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;
+};
+
+struct scmi_fc_db_info {
+	int width;
+	u64 set;
+	u64 mask;
+	void __iomem *addr;
+};
+
+struct scmi_fc_info {
+	void __iomem *level_set_addr;
+	void __iomem *limit_set_addr;
+	void __iomem *level_get_addr;
+	void __iomem *limit_get_addr;
+	struct scmi_fc_db_info *level_set_db;
+	struct scmi_fc_db_info *limit_set_db;
+};
+
 struct perf_dom_info {
 	bool set_limits;
 	bool set_perf;
 	bool perf_limit_notify;
 	bool perf_level_notify;
+	bool perf_fastchannels;
 	u32 opp_count;
 	u32 sustained_freq_khz;
 	u32 sustained_perf_level;
 	u32 mult_factor;
 	char name[SCMI_MAX_STR_SIZE];
 	struct scmi_opp opp[MAX_OPPS];
+	struct scmi_fc_info *fc_info;
 };
 
 struct scmi_perf_info {
@@ -151,7 +195,7 @@ scmi_perf_domain_attributes_get(const struct scmi_handle *handle, u32 domain,
 	if (ret)
 		return ret;
 
-	*(__le32 *)t->tx.buf = cpu_to_le32(domain);
+	put_unaligned_le32(domain, t->tx.buf);
 	attr = t->rx.buf;
 
 	ret = scmi_do_xfer(handle, t);
@@ -162,6 +206,7 @@ scmi_perf_domain_attributes_get(const struct scmi_handle *handle, u32 domain,
 		dom_info->set_perf = SUPPORTS_SET_PERF_LVL(flags);
 		dom_info->perf_limit_notify = SUPPORTS_PERF_LIMIT_NOTIFY(flags);
 		dom_info->perf_level_notify = SUPPORTS_PERF_LEVEL_NOTIFY(flags);
+		dom_info->perf_fastchannels = SUPPORTS_PERF_FASTCHANNELS(flags);
 		dom_info->sustained_freq_khz =
 					le32_to_cpu(attr->sustained_freq_khz);
 		dom_info->sustained_perf_level =
@@ -249,8 +294,42 @@ scmi_perf_describe_levels_get(const struct scmi_handle *handle, u32 domain,
 	return ret;
 }
 
-static int scmi_perf_limits_set(const struct scmi_handle *handle, u32 domain,
-				u32 max_perf, u32 min_perf)
+#define SCMI_PERF_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_perf_fc_ring_db(struct scmi_fc_db_info *db)
+{
+	if (!db || !db->addr)
+		return;
+
+	if (db->width == 1)
+		SCMI_PERF_FC_RING_DB(8);
+	else if (db->width == 2)
+		SCMI_PERF_FC_RING_DB(16);
+	else if (db->width == 4)
+		SCMI_PERF_FC_RING_DB(32);
+	else /* db->width == 8 */
+#ifdef CONFIG_64BIT
+		SCMI_PERF_FC_RING_DB(64);
+#else
+	{
+		u64 val = 0;
+
+		if (db->mask)
+			val = ioread64_hi_lo(db->addr) & db->mask;
+		iowrite64_hi_lo(db->set, db->addr);
+	}
+#endif
+}
+
+static int scmi_perf_mb_limits_set(const struct scmi_handle *handle, u32 domain,
+				   u32 max_perf, u32 min_perf)
 {
 	int ret;
 	struct scmi_xfer *t;
@@ -272,8 +351,24 @@ static int scmi_perf_limits_set(const struct scmi_handle *handle, u32 domain,
 	return ret;
 }
 
-static int scmi_perf_limits_get(const struct scmi_handle *handle, u32 domain,
-				u32 *max_perf, u32 *min_perf)
+static int scmi_perf_limits_set(const struct scmi_handle *handle, u32 domain,
+				u32 max_perf, u32 min_perf)
+{
+	struct scmi_perf_info *pi = handle->perf_priv;
+	struct perf_dom_info *dom = pi->dom_info + domain;
+
+	if (dom->fc_info && dom->fc_info->limit_set_addr) {
+		iowrite32(max_perf, dom->fc_info->limit_set_addr);
+		iowrite32(min_perf, dom->fc_info->limit_set_addr + 4);
+		scmi_perf_fc_ring_db(dom->fc_info->limit_set_db);
+		return 0;
+	}
+
+	return scmi_perf_mb_limits_set(handle, domain, max_perf, min_perf);
+}
+
+static int scmi_perf_mb_limits_get(const struct scmi_handle *handle, u32 domain,
+				   u32 *max_perf, u32 *min_perf)
 {
 	int ret;
 	struct scmi_xfer *t;
@@ -284,7 +379,7 @@ static int scmi_perf_limits_get(const struct scmi_handle *handle, u32 domain,
 	if (ret)
 		return ret;
 
-	*(__le32 *)t->tx.buf = cpu_to_le32(domain);
+	put_unaligned_le32(domain, t->tx.buf);
 
 	ret = scmi_do_xfer(handle, t);
 	if (!ret) {
@@ -298,8 +393,23 @@ static int scmi_perf_limits_get(const struct scmi_handle *handle, u32 domain,
 	return ret;
 }
 
-static int scmi_perf_level_set(const struct scmi_handle *handle, u32 domain,
-			       u32 level, bool poll)
+static int scmi_perf_limits_get(const struct scmi_handle *handle, u32 domain,
+				u32 *max_perf, u32 *min_perf)
+{
+	struct scmi_perf_info *pi = handle->perf_priv;
+	struct perf_dom_info *dom = pi->dom_info + domain;
+
+	if (dom->fc_info && dom->fc_info->limit_get_addr) {
+		*max_perf = ioread32(dom->fc_info->limit_get_addr);
+		*min_perf = ioread32(dom->fc_info->limit_get_addr + 4);
+		return 0;
+	}
+
+	return scmi_perf_mb_limits_get(handle, domain, max_perf, min_perf);
+}
+
+static int scmi_perf_mb_level_set(const struct scmi_handle *handle, u32 domain,
+				  u32 level, bool poll)
 {
 	int ret;
 	struct scmi_xfer *t;
@@ -321,8 +431,23 @@ static int scmi_perf_level_set(const struct scmi_handle *handle, u32 domain,
 	return ret;
 }
 
-static int scmi_perf_level_get(const struct scmi_handle *handle, u32 domain,
-			       u32 *level, bool poll)
+static int scmi_perf_level_set(const struct scmi_handle *handle, u32 domain,
+			       u32 level, bool poll)
+{
+	struct scmi_perf_info *pi = handle->perf_priv;
+	struct perf_dom_info *dom = pi->dom_info + domain;
+
+	if (dom->fc_info && dom->fc_info->level_set_addr) {
+		iowrite32(level, dom->fc_info->level_set_addr);
+		scmi_perf_fc_ring_db(dom->fc_info->level_set_db);
+		return 0;
+	}
+
+	return scmi_perf_mb_level_set(handle, domain, level, poll);
+}
+
+static int scmi_perf_mb_level_get(const struct scmi_handle *handle, u32 domain,
+				  u32 *level, bool poll)
 {
 	int ret;
 	struct scmi_xfer *t;
@@ -333,16 +458,128 @@ static int scmi_perf_level_get(const struct scmi_handle *handle, u32 domain,
 		return ret;
 
 	t->hdr.poll_completion = poll;
-	*(__le32 *)t->tx.buf = cpu_to_le32(domain);
+	put_unaligned_le32(domain, t->tx.buf);
 
 	ret = scmi_do_xfer(handle, t);
 	if (!ret)
-		*level = le32_to_cpu(*(__le32 *)t->rx.buf);
+		*level = get_unaligned_le32(t->rx.buf);
 
 	scmi_xfer_put(handle, t);
 	return ret;
 }
 
+static int scmi_perf_level_get(const struct scmi_handle *handle, u32 domain,
+			       u32 *level, bool poll)
+{
+	struct scmi_perf_info *pi = handle->perf_priv;
+	struct perf_dom_info *dom = pi->dom_info + domain;
+
+	if (dom->fc_info && dom->fc_info->level_get_addr) {
+		*level = ioread32(dom->fc_info->level_get_addr);
+		return 0;
+	}
+
+	return scmi_perf_mb_level_get(handle, domain, level, poll);
+}
+
+static bool scmi_perf_fc_size_is_valid(u32 msg, u32 size)
+{
+	if ((msg == PERF_LEVEL_GET || msg == PERF_LEVEL_SET) && size == 4)
+		return true;
+	if ((msg == PERF_LIMITS_GET || msg == PERF_LIMITS_SET) && size == 8)
+		return true;
+	return false;
+}
+
+static void
+scmi_perf_domain_desc_fc(const struct scmi_handle *handle, u32 domain,
+			 u32 message_id, 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;
+	struct scmi_perf_get_fc_info *info;
+	struct scmi_msg_resp_perf_desc_fc *resp;
+
+	if (!p_addr)
+		return;
+
+	ret = scmi_xfer_get_init(handle, PERF_DESCRIBE_FASTCHANNEL,
+				 SCMI_PROTOCOL_PERF,
+				 sizeof(*info), sizeof(*resp), &t);
+	if (ret)
+		return;
+
+	info = t->tx.buf;
+	info->domain = cpu_to_le32(domain);
+	info->message_id = cpu_to_le32(message_id);
+
+	ret = scmi_do_xfer(handle, t);
+	if (ret)
+		goto err_xfer;
+
+	resp = t->rx.buf;
+	flags = le32_to_cpu(resp->attr);
+	size = le32_to_cpu(resp->chan_size);
+	if (!scmi_perf_fc_size_is_valid(message_id, size))
+		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(handle->dev, phys_addr, size);
+	if (!addr)
+		goto err_xfer;
+	*p_addr = addr;
+
+	if (p_db && SUPPORTS_DOORBELL(flags)) {
+		db = devm_kzalloc(handle->dev, sizeof(*db), GFP_KERNEL);
+		if (!db)
+			goto err_xfer;
+
+		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(handle->dev, phys_addr, size);
+		if (!addr)
+			goto err_xfer;
+
+		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;
+	}
+err_xfer:
+	scmi_xfer_put(handle, t);
+}
+
+static void scmi_perf_domain_init_fc(const struct scmi_handle *handle,
+				     u32 domain, struct scmi_fc_info **p_fc)
+{
+	struct scmi_fc_info *fc;
+
+	fc = devm_kzalloc(handle->dev, sizeof(*fc), GFP_KERNEL);
+	if (!fc)
+		return;
+
+	scmi_perf_domain_desc_fc(handle, domain, PERF_LEVEL_SET,
+				 &fc->level_set_addr, &fc->level_set_db);
+	scmi_perf_domain_desc_fc(handle, domain, PERF_LEVEL_GET,
+				 &fc->level_get_addr, NULL);
+	scmi_perf_domain_desc_fc(handle, domain, PERF_LIMITS_SET,
+				 &fc->limit_set_addr, &fc->limit_set_db);
+	scmi_perf_domain_desc_fc(handle, domain, PERF_LIMITS_GET,
+				 &fc->limit_get_addr, NULL);
+	*p_fc = fc;
+}
+
 /* Device specific ops */
 static int scmi_dev_domain_id(struct device *dev)
 {
@@ -494,6 +731,9 @@ static int scmi_perf_protocol_init(struct scmi_handle *handle)
 
 		scmi_perf_domain_attributes_get(handle, domain, dom);
 		scmi_perf_describe_levels_get(handle, domain, dom);
+
+		if (dom->perf_fastchannels)
+			scmi_perf_domain_init_fc(handle, domain, &dom->fc_info);
 	}
 
 	handle->perf_ops = &perf_ops;
diff --git a/drivers/firmware/arm_scmi/power.c b/drivers/firmware/arm_scmi/power.c
index 62f3401a1f01..5abef7079c0a 100644
--- a/drivers/firmware/arm_scmi/power.c
+++ b/drivers/firmware/arm_scmi/power.c
@@ -96,7 +96,7 @@ scmi_power_domain_attributes_get(const struct scmi_handle *handle, u32 domain,
 	if (ret)
 		return ret;
 
-	*(__le32 *)t->tx.buf = cpu_to_le32(domain);
+	put_unaligned_le32(domain, t->tx.buf);
 	attr = t->rx.buf;
 
 	ret = scmi_do_xfer(handle, t);
@@ -147,11 +147,11 @@ scmi_power_state_get(const struct scmi_handle *handle, u32 domain, u32 *state)
 	if (ret)
 		return ret;
 
-	*(__le32 *)t->tx.buf = cpu_to_le32(domain);
+	put_unaligned_le32(domain, t->tx.buf);
 
 	ret = scmi_do_xfer(handle, t);
 	if (!ret)
-		*state = le32_to_cpu(*(__le32 *)t->rx.buf);
+		*state = get_unaligned_le32(t->rx.buf);
 
 	scmi_xfer_put(handle, t);
 	return ret;
diff --git a/drivers/firmware/arm_scmi/reset.c b/drivers/firmware/arm_scmi/reset.c
new file mode 100644
index 000000000000..64cc81915581
--- /dev/null
+++ b/drivers/firmware/arm_scmi/reset.c
@@ -0,0 +1,231 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Reset Protocol
+ *
+ * Copyright (C) 2019 ARM Ltd.
+ */
+
+#include "common.h"
+
+enum scmi_reset_protocol_cmd {
+	RESET_DOMAIN_ATTRIBUTES = 0x3,
+	RESET = 0x4,
+	RESET_NOTIFY = 0x5,
+};
+
+enum scmi_reset_protocol_notify {
+	RESET_ISSUED = 0x0,
+};
+
+#define NUM_RESET_DOMAIN_MASK	0xffff
+#define RESET_NOTIFY_ENABLE	BIT(0)
+
+struct scmi_msg_resp_reset_domain_attributes {
+	__le32 attributes;
+#define SUPPORTS_ASYNC_RESET(x)		((x) & BIT(31))
+#define SUPPORTS_NOTIFY_RESET(x)	((x) & BIT(30))
+	__le32 latency;
+	    u8 name[SCMI_MAX_STR_SIZE];
+};
+
+struct scmi_msg_reset_domain_reset {
+	__le32 domain_id;
+	__le32 flags;
+#define AUTONOMOUS_RESET	BIT(0)
+#define EXPLICIT_RESET_ASSERT	BIT(1)
+#define ASYNCHRONOUS_RESET	BIT(2)
+	__le32 reset_state;
+#define ARCH_RESET_TYPE		BIT(31)
+#define COLD_RESET_STATE	BIT(0)
+#define ARCH_COLD_RESET		(ARCH_RESET_TYPE | COLD_RESET_STATE)
+};
+
+struct reset_dom_info {
+	bool async_reset;
+	bool reset_notify;
+	u32 latency_us;
+	char name[SCMI_MAX_STR_SIZE];
+};
+
+struct scmi_reset_info {
+	int num_domains;
+	struct reset_dom_info *dom_info;
+};
+
+static int scmi_reset_attributes_get(const struct scmi_handle *handle,
+				     struct scmi_reset_info *pi)
+{
+	int ret;
+	struct scmi_xfer *t;
+	u32 attr;
+
+	ret = scmi_xfer_get_init(handle, PROTOCOL_ATTRIBUTES,
+				 SCMI_PROTOCOL_RESET, 0, sizeof(attr), &t);
+	if (ret)
+		return ret;
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret) {
+		attr = get_unaligned_le32(t->rx.buf);
+		pi->num_domains = attr & NUM_RESET_DOMAIN_MASK;
+	}
+
+	scmi_xfer_put(handle, t);
+	return ret;
+}
+
+static int
+scmi_reset_domain_attributes_get(const struct scmi_handle *handle, u32 domain,
+				 struct reset_dom_info *dom_info)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_msg_resp_reset_domain_attributes *attr;
+
+	ret = scmi_xfer_get_init(handle, RESET_DOMAIN_ATTRIBUTES,
+				 SCMI_PROTOCOL_RESET, sizeof(domain),
+				 sizeof(*attr), &t);
+	if (ret)
+		return ret;
+
+	put_unaligned_le32(domain, t->tx.buf);
+	attr = t->rx.buf;
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret) {
+		u32 attributes = le32_to_cpu(attr->attributes);
+
+		dom_info->async_reset = SUPPORTS_ASYNC_RESET(attributes);
+		dom_info->reset_notify = SUPPORTS_NOTIFY_RESET(attributes);
+		dom_info->latency_us = le32_to_cpu(attr->latency);
+		if (dom_info->latency_us == U32_MAX)
+			dom_info->latency_us = 0;
+		strlcpy(dom_info->name, attr->name, SCMI_MAX_STR_SIZE);
+	}
+
+	scmi_xfer_put(handle, t);
+	return ret;
+}
+
+static int scmi_reset_num_domains_get(const struct scmi_handle *handle)
+{
+	struct scmi_reset_info *pi = handle->reset_priv;
+
+	return pi->num_domains;
+}
+
+static char *scmi_reset_name_get(const struct scmi_handle *handle, u32 domain)
+{
+	struct scmi_reset_info *pi = handle->reset_priv;
+	struct reset_dom_info *dom = pi->dom_info + domain;
+
+	return dom->name;
+}
+
+static int scmi_reset_latency_get(const struct scmi_handle *handle, u32 domain)
+{
+	struct scmi_reset_info *pi = handle->reset_priv;
+	struct reset_dom_info *dom = pi->dom_info + domain;
+
+	return dom->latency_us;
+}
+
+static int scmi_domain_reset(const struct scmi_handle *handle, u32 domain,
+			     u32 flags, u32 state)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_msg_reset_domain_reset *dom;
+	struct scmi_reset_info *pi = handle->reset_priv;
+	struct reset_dom_info *rdom = pi->dom_info + domain;
+
+	if (rdom->async_reset)
+		flags |= ASYNCHRONOUS_RESET;
+
+	ret = scmi_xfer_get_init(handle, RESET, SCMI_PROTOCOL_RESET,
+				 sizeof(*dom), 0, &t);
+	if (ret)
+		return ret;
+
+	dom = t->tx.buf;
+	dom->domain_id = cpu_to_le32(domain);
+	dom->flags = cpu_to_le32(flags);
+	dom->domain_id = cpu_to_le32(state);
+
+	if (rdom->async_reset)
+		ret = scmi_do_xfer_with_response(handle, t);
+	else
+		ret = scmi_do_xfer(handle, t);
+
+	scmi_xfer_put(handle, t);
+	return ret;
+}
+
+static int scmi_reset_domain_reset(const struct scmi_handle *handle, u32 domain)
+{
+	return scmi_domain_reset(handle, domain, AUTONOMOUS_RESET,
+				 ARCH_COLD_RESET);
+}
+
+static int
+scmi_reset_domain_assert(const struct scmi_handle *handle, u32 domain)
+{
+	return scmi_domain_reset(handle, domain, EXPLICIT_RESET_ASSERT,
+				 ARCH_COLD_RESET);
+}
+
+static int
+scmi_reset_domain_deassert(const struct scmi_handle *handle, u32 domain)
+{
+	return scmi_domain_reset(handle, domain, 0, ARCH_COLD_RESET);
+}
+
+static struct scmi_reset_ops reset_ops = {
+	.num_domains_get = scmi_reset_num_domains_get,
+	.name_get = scmi_reset_name_get,
+	.latency_get = scmi_reset_latency_get,
+	.reset = scmi_reset_domain_reset,
+	.assert = scmi_reset_domain_assert,
+	.deassert = scmi_reset_domain_deassert,
+};
+
+static int scmi_reset_protocol_init(struct scmi_handle *handle)
+{
+	int domain;
+	u32 version;
+	struct scmi_reset_info *pinfo;
+
+	scmi_version_get(handle, SCMI_PROTOCOL_RESET, &version);
+
+	dev_dbg(handle->dev, "Reset Version %d.%d\n",
+		PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
+
+	pinfo = devm_kzalloc(handle->dev, sizeof(*pinfo), GFP_KERNEL);
+	if (!pinfo)
+		return -ENOMEM;
+
+	scmi_reset_attributes_get(handle, pinfo);
+
+	pinfo->dom_info = devm_kcalloc(handle->dev, pinfo->num_domains,
+				       sizeof(*pinfo->dom_info), GFP_KERNEL);
+	if (!pinfo->dom_info)
+		return -ENOMEM;
+
+	for (domain = 0; domain < pinfo->num_domains; domain++) {
+		struct reset_dom_info *dom = pinfo->dom_info + domain;
+
+		scmi_reset_domain_attributes_get(handle, domain, dom);
+	}
+
+	handle->reset_ops = &reset_ops;
+	handle->reset_priv = pinfo;
+
+	return 0;
+}
+
+static int __init scmi_reset_init(void)
+{
+	return scmi_protocol_register(SCMI_PROTOCOL_RESET,
+				      &scmi_reset_protocol_init);
+}
+subsys_initcall(scmi_reset_init);
diff --git a/drivers/firmware/arm_scmi/sensors.c b/drivers/firmware/arm_scmi/sensors.c
index 0e94ab56f679..a400ea805fc2 100644
--- a/drivers/firmware/arm_scmi/sensors.c
+++ b/drivers/firmware/arm_scmi/sensors.c
@@ -9,8 +9,8 @@
 
 enum scmi_sensor_protocol_cmd {
 	SENSOR_DESCRIPTION_GET = 0x3,
-	SENSOR_CONFIG_SET = 0x4,
-	SENSOR_TRIP_POINT_SET = 0x5,
+	SENSOR_TRIP_POINT_NOTIFY = 0x4,
+	SENSOR_TRIP_POINT_CONFIG = 0x5,
 	SENSOR_READING_GET = 0x6,
 };
 
@@ -42,9 +42,10 @@ struct scmi_msg_resp_sensor_description {
 	} desc[0];
 };
 
-struct scmi_msg_set_sensor_config {
+struct scmi_msg_sensor_trip_point_notify {
 	__le32 id;
 	__le32 event_control;
+#define SENSOR_TP_NOTIFY_ALL	BIT(0)
 };
 
 struct scmi_msg_set_sensor_trip_point {
@@ -119,7 +120,7 @@ static int scmi_sensor_description_get(const struct scmi_handle *handle,
 
 	do {
 		/* Set the number of sensors to be skipped/already read */
-		*(__le32 *)t->tx.buf = cpu_to_le32(desc_index);
+		put_unaligned_le32(desc_index, t->tx.buf);
 
 		ret = scmi_do_xfer(handle, t);
 		if (ret)
@@ -135,9 +136,10 @@ static int scmi_sensor_description_get(const struct scmi_handle *handle,
 		}
 
 		for (cnt = 0; cnt < num_returned; cnt++) {
-			u32 attrh;
+			u32 attrh, attrl;
 			struct scmi_sensor_info *s;
 
+			attrl = le32_to_cpu(buf->desc[cnt].attributes_low);
 			attrh = le32_to_cpu(buf->desc[cnt].attributes_high);
 			s = &si->sensors[desc_index + cnt];
 			s->id = le32_to_cpu(buf->desc[cnt].id);
@@ -146,6 +148,8 @@ static int scmi_sensor_description_get(const struct scmi_handle *handle,
 			/* Sign extend to a full s8 */
 			if (s->scale & SENSOR_SCALE_SIGN)
 				s->scale |= SENSOR_SCALE_EXTEND;
+			s->async = SUPPORTS_ASYNC_READ(attrl);
+			s->num_trip_points = NUM_TRIP_POINTS(attrl);
 			strlcpy(s->name, buf->desc[cnt].name, SCMI_MAX_STR_SIZE);
 		}
 
@@ -160,15 +164,15 @@ static int scmi_sensor_description_get(const struct scmi_handle *handle,
 	return ret;
 }
 
-static int
-scmi_sensor_configuration_set(const struct scmi_handle *handle, u32 sensor_id)
+static int scmi_sensor_trip_point_notify(const struct scmi_handle *handle,
+					 u32 sensor_id, bool enable)
 {
 	int ret;
-	u32 evt_cntl = BIT(0);
+	u32 evt_cntl = enable ? SENSOR_TP_NOTIFY_ALL : 0;
 	struct scmi_xfer *t;
-	struct scmi_msg_set_sensor_config *cfg;
+	struct scmi_msg_sensor_trip_point_notify *cfg;
 
-	ret = scmi_xfer_get_init(handle, SENSOR_CONFIG_SET,
+	ret = scmi_xfer_get_init(handle, SENSOR_TRIP_POINT_NOTIFY,
 				 SCMI_PROTOCOL_SENSOR, sizeof(*cfg), 0, &t);
 	if (ret)
 		return ret;
@@ -183,15 +187,16 @@ scmi_sensor_configuration_set(const struct scmi_handle *handle, u32 sensor_id)
 	return ret;
 }
 
-static int scmi_sensor_trip_point_set(const struct scmi_handle *handle,
-				      u32 sensor_id, u8 trip_id, u64 trip_value)
+static int
+scmi_sensor_trip_point_config(const struct scmi_handle *handle, u32 sensor_id,
+			      u8 trip_id, u64 trip_value)
 {
 	int ret;
 	u32 evt_cntl = SENSOR_TP_BOTH;
 	struct scmi_xfer *t;
 	struct scmi_msg_set_sensor_trip_point *trip;
 
-	ret = scmi_xfer_get_init(handle, SENSOR_TRIP_POINT_SET,
+	ret = scmi_xfer_get_init(handle, SENSOR_TRIP_POINT_CONFIG,
 				 SCMI_PROTOCOL_SENSOR, sizeof(*trip), 0, &t);
 	if (ret)
 		return ret;
@@ -209,11 +214,13 @@ static int scmi_sensor_trip_point_set(const struct scmi_handle *handle,
 }
 
 static int scmi_sensor_reading_get(const struct scmi_handle *handle,
-				   u32 sensor_id, bool async, u64 *value)
+				   u32 sensor_id, u64 *value)
 {
 	int ret;
 	struct scmi_xfer *t;
 	struct scmi_msg_sensor_reading_get *sensor;
+	struct sensors_info *si = handle->sensor_priv;
+	struct scmi_sensor_info *s = si->sensors + sensor_id;
 
 	ret = scmi_xfer_get_init(handle, SENSOR_READING_GET,
 				 SCMI_PROTOCOL_SENSOR, sizeof(*sensor),
@@ -223,14 +230,18 @@ static int scmi_sensor_reading_get(const struct scmi_handle *handle,
 
 	sensor = t->tx.buf;
 	sensor->id = cpu_to_le32(sensor_id);
-	sensor->flags = cpu_to_le32(async ? SENSOR_READ_ASYNC : 0);
 
-	ret = scmi_do_xfer(handle, t);
-	if (!ret) {
-		__le32 *pval = t->rx.buf;
-
-		*value = le32_to_cpu(*pval);
-		*value |= (u64)le32_to_cpu(*(pval + 1)) << 32;
+	if (s->async) {
+		sensor->flags = cpu_to_le32(SENSOR_READ_ASYNC);
+		ret = scmi_do_xfer_with_response(handle, t);
+		if (!ret)
+			*value = get_unaligned_le64((void *)
+						    ((__le32 *)t->rx.buf + 1));
+	} else {
+		sensor->flags = cpu_to_le32(0);
+		ret = scmi_do_xfer(handle, t);
+		if (!ret)
+			*value = get_unaligned_le64(t->rx.buf);
 	}
 
 	scmi_xfer_put(handle, t);
@@ -255,8 +266,8 @@ static int scmi_sensor_count_get(const struct scmi_handle *handle)
 static struct scmi_sensor_ops sensor_ops = {
 	.count_get = scmi_sensor_count_get,
 	.info_get = scmi_sensor_info_get,
-	.configuration_set = scmi_sensor_configuration_set,
-	.trip_point_set = scmi_sensor_trip_point_set,
+	.trip_point_notify = scmi_sensor_trip_point_notify,
+	.trip_point_config = scmi_sensor_trip_point_config,
 	.reading_get = scmi_sensor_reading_get,
 };
 
diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c
index 0c93fc5ca762..8a7732c0bef3 100644
--- a/drivers/hwmon/scmi-hwmon.c
+++ b/drivers/hwmon/scmi-hwmon.c
@@ -72,7 +72,7 @@ static int scmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
 	const struct scmi_handle *h = scmi_sensors->handle;
 
 	sensor = *(scmi_sensors->info[type] + channel);
-	ret = h->sensor_ops->reading_get(h, sensor->id, false, &value);
+	ret = h->sensor_ops->reading_get(h, sensor->id, &value);
 	if (ret)
 		return ret;
 
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 6d5d76db55b0..7b07281aa0ae 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -116,6 +116,17 @@ config RESET_QCOM_PDC
 	  to control reset signals provided by PDC for Modem, Compute,
 	  Display, GPU, Debug, AOP, Sensors, Audio, SP and APPS.
 
+config RESET_SCMI
+	tristate "Reset driver controlled via ARM SCMI interface"
+	depends on ARM_SCMI_PROTOCOL || COMPILE_TEST
+	default ARM_SCMI_PROTOCOL
+	help
+	  This driver provides support for reset signal/domains that are
+	  controlled by firmware that implements the SCMI interface.
+
+	  This driver uses SCMI Message Protocol to interact with the
+	  firmware controlling all the reset signals.
+
 config RESET_SIMPLE
 	bool "Simple Reset Controller Driver" if COMPILE_TEST
 	default ARCH_STM32 || ARCH_STRATIX10 || ARCH_SUNXI || ARCH_ZX || ARCH_ASPEED || ARCH_BITMAIN || ARC
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 61456b8f659c..cf60ce526064 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
 obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
 obj-$(CONFIG_RESET_QCOM_AOSS) += reset-qcom-aoss.o
 obj-$(CONFIG_RESET_QCOM_PDC) += reset-qcom-pdc.o
+obj-$(CONFIG_RESET_SCMI) += reset-scmi.o
 obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o
 obj-$(CONFIG_RESET_STM32MP157) += reset-stm32mp1.o
 obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o
diff --git a/drivers/reset/reset-scmi.c b/drivers/reset/reset-scmi.c
new file mode 100644
index 000000000000..c6d3c8427f14
--- /dev/null
+++ b/drivers/reset/reset-scmi.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM System Control and Management Interface (ARM SCMI) reset driver
+ *
+ * Copyright (C) 2019 ARM Ltd.
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/device.h>
+#include <linux/reset-controller.h>
+#include <linux/scmi_protocol.h>
+
+/**
+ * struct scmi_reset_data - reset controller information structure
+ * @rcdev: reset controller entity
+ * @handle: ARM SCMI handle used for communication with system controller
+ */
+struct scmi_reset_data {
+	struct reset_controller_dev rcdev;
+	const struct scmi_handle *handle;
+};
+
+#define to_scmi_reset_data(p)	container_of((p), struct scmi_reset_data, rcdev)
+#define to_scmi_handle(p)	(to_scmi_reset_data(p)->handle)
+
+/**
+ * scmi_reset_assert() - assert device reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to be asserted
+ *
+ * This function implements the reset driver op to assert a device's reset
+ * using the ARM SCMI protocol.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int
+scmi_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	const struct scmi_handle *handle = to_scmi_handle(rcdev);
+
+	return handle->reset_ops->assert(handle, id);
+}
+
+/**
+ * scmi_reset_deassert() - deassert device reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to be deasserted
+ *
+ * This function implements the reset driver op to deassert a device's reset
+ * using the ARM SCMI protocol.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int
+scmi_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	const struct scmi_handle *handle = to_scmi_handle(rcdev);
+
+	return handle->reset_ops->deassert(handle, id);
+}
+
+/**
+ * scmi_reset_reset() - reset the device
+ * @rcdev: reset controller entity
+ * @id: ID of the reset signal to be reset(assert + deassert)
+ *
+ * This function implements the reset driver op to trigger a device's
+ * reset signal using the ARM SCMI protocol.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int
+scmi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	const struct scmi_handle *handle = to_scmi_handle(rcdev);
+
+	return handle->reset_ops->reset(handle, id);
+}
+
+static const struct reset_control_ops scmi_reset_ops = {
+	.assert		= scmi_reset_assert,
+	.deassert	= scmi_reset_deassert,
+	.reset		= scmi_reset_reset,
+};
+
+static int scmi_reset_probe(struct scmi_device *sdev)
+{
+	struct scmi_reset_data *data;
+	struct device *dev = &sdev->dev;
+	struct device_node *np = dev->of_node;
+	const struct scmi_handle *handle = sdev->handle;
+
+	if (!handle || !handle->reset_ops)
+		return -ENODEV;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->rcdev.ops = &scmi_reset_ops;
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.of_node = np;
+	data->rcdev.nr_resets = handle->reset_ops->num_domains_get(handle);
+
+	return devm_reset_controller_register(dev, &data->rcdev);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+	{ SCMI_PROTOCOL_RESET },
+	{ },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_reset_driver = {
+	.name = "scmi-reset",
+	.probe = scmi_reset_probe,
+	.id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_reset_driver);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI reset controller driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index 9ff2e9357e9a..881fea47c83d 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * SCMI Message Protocol driver header
  *
@@ -71,7 +71,7 @@ struct scmi_clk_ops {
 	int (*rate_get)(const struct scmi_handle *handle, u32 clk_id,
 			u64 *rate);
 	int (*rate_set)(const struct scmi_handle *handle, u32 clk_id,
-			u32 config, u64 rate);
+			u64 rate);
 	int (*enable)(const struct scmi_handle *handle, u32 clk_id);
 	int (*disable)(const struct scmi_handle *handle, u32 clk_id);
 };
@@ -145,6 +145,8 @@ struct scmi_sensor_info {
 	u32 id;
 	u8 type;
 	s8 scale;
+	u8 num_trip_points;
+	bool async;
 	char name[SCMI_MAX_STR_SIZE];
 };
 
@@ -167,9 +169,9 @@ enum scmi_sensor_class {
  *
  * @count_get: get the count of sensors provided by SCMI
  * @info_get: get the information of the specified sensor
- * @configuration_set: control notifications on cross-over events for
+ * @trip_point_notify: control notifications on cross-over events for
  *	the trip-points
- * @trip_point_set: selects and configures a trip-point of interest
+ * @trip_point_config: selects and configures a trip-point of interest
  * @reading_get: gets the current value of the sensor
  */
 struct scmi_sensor_ops {
@@ -177,12 +179,32 @@ struct scmi_sensor_ops {
 
 	const struct scmi_sensor_info *(*info_get)
 		(const struct scmi_handle *handle, u32 sensor_id);
-	int (*configuration_set)(const struct scmi_handle *handle,
-				 u32 sensor_id);
-	int (*trip_point_set)(const struct scmi_handle *handle, u32 sensor_id,
-			      u8 trip_id, u64 trip_value);
+	int (*trip_point_notify)(const struct scmi_handle *handle,
+				 u32 sensor_id, bool enable);
+	int (*trip_point_config)(const struct scmi_handle *handle,
+				 u32 sensor_id, u8 trip_id, u64 trip_value);
 	int (*reading_get)(const struct scmi_handle *handle, u32 sensor_id,
-			   bool async, u64 *value);
+			   u64 *value);
+};
+
+/**
+ * struct scmi_reset_ops - represents the various operations provided
+ *	by SCMI Reset Protocol
+ *
+ * @num_domains_get: get the count of reset domains provided by SCMI
+ * @name_get: gets the name of a reset domain
+ * @latency_get: gets the reset latency for the specified reset domain
+ * @reset: resets the specified reset domain
+ * @assert: explicitly assert reset signal of the specified reset domain
+ * @deassert: explicitly deassert reset signal of the specified reset domain
+ */
+struct scmi_reset_ops {
+	int (*num_domains_get)(const struct scmi_handle *handle);
+	char *(*name_get)(const struct scmi_handle *handle, u32 domain);
+	int (*latency_get)(const struct scmi_handle *handle, u32 domain);
+	int (*reset)(const struct scmi_handle *handle, u32 domain);
+	int (*assert)(const struct scmi_handle *handle, u32 domain);
+	int (*deassert)(const struct scmi_handle *handle, u32 domain);
 };
 
 /**
@@ -194,6 +216,7 @@ struct scmi_sensor_ops {
  * @perf_ops: pointer to set of performance protocol operations
  * @clk_ops: pointer to set of clock protocol operations
  * @sensor_ops: pointer to set of sensor protocol operations
+ * @reset_ops: pointer to set of reset protocol operations
  * @perf_priv: pointer to private data structure specific to performance
  *	protocol(for internal use only)
  * @clk_priv: pointer to private data structure specific to clock
@@ -202,6 +225,8 @@ struct scmi_sensor_ops {
  *	protocol(for internal use only)
  * @sensor_priv: pointer to private data structure specific to sensors
  *	protocol(for internal use only)
+ * @reset_priv: pointer to private data structure specific to reset
+ *	protocol(for internal use only)
  */
 struct scmi_handle {
 	struct device *dev;
@@ -210,11 +235,13 @@ struct scmi_handle {
 	struct scmi_clk_ops *clk_ops;
 	struct scmi_power_ops *power_ops;
 	struct scmi_sensor_ops *sensor_ops;
+	struct scmi_reset_ops *reset_ops;
 	/* for protocol internal use */
 	void *perf_priv;
 	void *clk_priv;
 	void *power_priv;
 	void *sensor_priv;
+	void *reset_priv;
 };
 
 enum scmi_std_protocol {
@@ -224,6 +251,7 @@ enum scmi_std_protocol {
 	SCMI_PROTOCOL_PERF = 0x13,
 	SCMI_PROTOCOL_CLOCK = 0x14,
 	SCMI_PROTOCOL_SENSOR = 0x15,
+	SCMI_PROTOCOL_RESET = 0x16,
 };
 
 struct scmi_device {