--- /dev/null
+From 36269e8f5fa1f33a793c472935affe3039c052bd Mon Sep 17 00:00:00 2001
+From: Igor Skalkin <igor.skalkin@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:07 +0100
+Subject: [PATCH] firmware: arm_scmi, smccc, mailbox: Make shmem based
+ transports optional
+
+Upon adding the virtio transport in this patch series, SCMI will also
+work without shared memory based transports. Also, the mailbox transport
+may not be needed if the smc transport is used.
+
+- Compile shmem.c only if a shmem based transport is available.
+
+- Remove hard dependency of SCMI on mailbox.
+
+Co-developed-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Igor Skalkin <igor.skalkin@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ drivers/firmware/Kconfig | 9 ++++++++-
+ drivers/firmware/arm_scmi/Makefile | 2 +-
+ drivers/firmware/arm_scmi/common.h | 2 ++
+ drivers/firmware/arm_scmi/driver.c | 2 ++
+ drivers/firmware/smccc/Kconfig | 1 +
+ drivers/mailbox/Kconfig | 1 +
+ 6 files changed, 15 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
+index 3315e3c21586..30a85d38d0c0 100644
+--- a/drivers/firmware/Kconfig
++++ b/drivers/firmware/Kconfig
+@@ -9,7 +9,7 @@ menu "Firmware Drivers"
+ config ARM_SCMI_PROTOCOL
+ tristate "ARM System Control and Management Interface (SCMI) Message Protocol"
+ depends on ARM || ARM64 || COMPILE_TEST
+- depends on MAILBOX
++ depends on ARM_SCMI_HAVE_SHMEM
+ help
+ ARM System Control and Management Interface (SCMI) protocol is a
+ set of operating system-independent software interfaces that are
+@@ -27,6 +27,13 @@ config ARM_SCMI_PROTOCOL
+ This protocol library provides interface for all the client drivers
+ making use of the features offered by the SCMI.
+
++config ARM_SCMI_HAVE_SHMEM
++ bool
++ default n
++ help
++ This declares whether a shared memory based transport for SCMI is
++ available.
++
+ config ARM_SCMI_POWER_DOMAIN
+ tristate "SCMI power domain driver"
+ depends on ARM_SCMI_PROTOCOL || (COMPILE_TEST && OF)
+diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
+index bc0d54f8e861..3cc7fa40a464 100644
+--- a/drivers/firmware/arm_scmi/Makefile
++++ b/drivers/firmware/arm_scmi/Makefile
+@@ -1,7 +1,7 @@
+ # SPDX-License-Identifier: GPL-2.0-only
+ scmi-bus-y = bus.o
+ scmi-driver-y = driver.o notify.o
+-scmi-transport-y = shmem.o
++scmi-transport-$(CONFIG_ARM_SCMI_HAVE_SHMEM) = shmem.o
+ scmi-transport-$(CONFIG_MAILBOX) += mailbox.o
+ scmi-transport-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smc.o
+ scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o
+diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
+index 65063fa948d4..aed192238177 100644
+--- a/drivers/firmware/arm_scmi/common.h
++++ b/drivers/firmware/arm_scmi/common.h
+@@ -242,7 +242,9 @@ struct scmi_desc {
+ int max_msg_size;
+ };
+
++#ifdef CONFIG_MAILBOX
+ extern const struct scmi_desc scmi_mailbox_desc;
++#endif
+ #ifdef CONFIG_HAVE_ARM_SMCCC
+ extern const struct scmi_desc scmi_smc_desc;
+ #endif
+diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
+index 6b2ce3f28f7b..7efbf66f117b 100644
+--- a/drivers/firmware/arm_scmi/driver.c
++++ b/drivers/firmware/arm_scmi/driver.c
+@@ -918,7 +918,9 @@ ATTRIBUTE_GROUPS(versions);
+
+ /* Each compatible listed below must have descriptor associated with it */
+ static const struct of_device_id scmi_of_match[] = {
++#ifdef CONFIG_MAILBOX
+ { .compatible = "arm,scmi", .data = &scmi_mailbox_desc },
++#endif
+ #ifdef CONFIG_HAVE_ARM_SMCCC_DISCOVERY
+ { .compatible = "arm,scmi-smc", .data = &scmi_smc_desc},
+ #endif
+diff --git a/drivers/firmware/smccc/Kconfig b/drivers/firmware/smccc/Kconfig
+index 15e7466179a6..69c4d6cabf62 100644
+--- a/drivers/firmware/smccc/Kconfig
++++ b/drivers/firmware/smccc/Kconfig
+@@ -9,6 +9,7 @@ config HAVE_ARM_SMCCC_DISCOVERY
+ bool
+ depends on ARM_PSCI_FW
+ default y
++ select ARM_SCMI_HAVE_SHMEM
+ help
+ SMCCC v1.0 lacked discoverability and hence PSCI v1.0 was updated
+ to add SMCCC discovery mechanism though the PSCI firmware
+diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
+index 05b1009e2820..5ffe1ab0c869 100644
+--- a/drivers/mailbox/Kconfig
++++ b/drivers/mailbox/Kconfig
+@@ -1,6 +1,7 @@
+ # SPDX-License-Identifier: GPL-2.0-only
+ menuconfig MAILBOX
+ bool "Mailbox Hardware Support"
++ select ARM_SCMI_HAVE_SHMEM
+ help
+ Mailbox is a framework to control hardware communication between
+ on-chip processors through queued messages and interrupt driven
--- /dev/null
+From 30de0a5e1fec42589469e5ec8951d15d364df63a Mon Sep 17 00:00:00 2001
+From: Igor Skalkin <igor.skalkin@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:08 +0100
+Subject: [PATCH] firmware: arm_scmi: Document that max_msg is a per channel
+ type limit
+
+struct scmi_desc.max_msg specifies a limit for the pending messages.
+This limit is a per SCMI channel type (tx, rx) limit. State that
+explicitly in the inline documentation. The following patch will add an
+op to override the limit per channel type.
+
+Co-developed-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Igor Skalkin <igor.skalkin@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ drivers/firmware/arm_scmi/common.h | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
+index aed192238177..38e6aabbe3dd 100644
+--- a/drivers/firmware/arm_scmi/common.h
++++ b/drivers/firmware/arm_scmi/common.h
+@@ -231,8 +231,8 @@ struct scmi_transport_ops {
+ *
+ * @ops: Pointer to the transport specific ops structure
+ * @max_rx_timeout_ms: Timeout for communication with SoC (in Milliseconds)
+- * @max_msg: Maximum number of messages that can be pending
+- * simultaneously in the system
++ * @max_msg: Maximum number of messages for a channel type (tx or rx) that can
++ * be pending simultaneously in the system
+ * @max_msg_size: Maximum size of data per message that can be handled.
+ */
+ struct scmi_desc {
--- /dev/null
+From 9ffe778acc541cec68c954f84c6fcfef8a35bec2 Mon Sep 17 00:00:00 2001
+From: Igor Skalkin <igor.skalkin@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:09 +0100
+Subject: [PATCH] firmware: arm_scmi: Add op to override max message #
+
+The number of messages that the upcoming scmi-virtio transport can
+support depends on the virtio device (SCMI platform) and can differ for
+each channel. (The scmi-virtio transport does only have one tx and at
+most 1 rx channel.)
+
+Add an optional transport op so that scmi-virtio can report the actual
+max message # for each channel type. Respect these new limits.
+
+Co-developed-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Igor Skalkin <igor.skalkin@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ drivers/firmware/arm_scmi/common.h | 8 ++++-
+ drivers/firmware/arm_scmi/driver.c | 49 ++++++++++++++++++++++--------
+ 2 files changed, 43 insertions(+), 14 deletions(-)
+
+diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
+index 38e6aabbe3dd..9a8359ecd220 100644
+--- a/drivers/firmware/arm_scmi/common.h
++++ b/drivers/firmware/arm_scmi/common.h
+@@ -203,6 +203,9 @@ struct scmi_chan_info {
+ * @chan_available: Callback to check if channel is available or not
+ * @chan_setup: Callback to allocate and setup a channel
+ * @chan_free: Callback to free a channel
++ * @get_max_msg: Optional callback to provide max_msg dynamically
++ * @max_msg: Maximum number of messages for the channel type (tx or rx)
++ * that can be pending simultaneously in the system
+ * @send_message: Callback to send a message
+ * @mark_txdone: Callback to mark tx as done
+ * @fetch_response: Callback to fetch response
+@@ -215,6 +218,8 @@ struct scmi_transport_ops {
+ int (*chan_setup)(struct scmi_chan_info *cinfo, struct device *dev,
+ bool tx);
+ int (*chan_free)(int id, void *p, void *data);
++ int (*get_max_msg)(bool tx, struct scmi_chan_info *base_cinfo,
++ int *max_msg);
+ int (*send_message)(struct scmi_chan_info *cinfo,
+ struct scmi_xfer *xfer);
+ void (*mark_txdone)(struct scmi_chan_info *cinfo, int ret);
+@@ -232,7 +237,8 @@ struct scmi_transport_ops {
+ * @ops: Pointer to the transport specific ops structure
+ * @max_rx_timeout_ms: Timeout for communication with SoC (in Milliseconds)
+ * @max_msg: Maximum number of messages for a channel type (tx or rx) that can
+- * be pending simultaneously in the system
++ * be pending simultaneously in the system. May be overridden by the
++ * get_max_msg op.
+ * @max_msg_size: Maximum size of data per message that can be handled.
+ */
+ struct scmi_desc {
+diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
+index 7efbf66f117b..5baa23789a49 100644
+--- a/drivers/firmware/arm_scmi/driver.c
++++ b/drivers/firmware/arm_scmi/driver.c
+@@ -61,11 +61,13 @@ static atomic_t transfer_last_id;
+ * Index of this bitmap table is also used for message
+ * sequence identifier.
+ * @xfer_lock: Protection for message allocation
++ * @max_msg: Maximum number of messages that can be pending
+ */
+ struct scmi_xfers_info {
+ struct scmi_xfer *xfer_block;
+ unsigned long *xfer_alloc_table;
+ spinlock_t xfer_lock;
++ int max_msg;
+ };
+
+ /**
+@@ -157,13 +159,11 @@ static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle,
+ u16 xfer_id;
+ struct scmi_xfer *xfer;
+ unsigned long flags, bit_pos;
+- struct scmi_info *info = handle_to_scmi_info(handle);
+
+ /* Keep the locked section as small as possible */
+ spin_lock_irqsave(&minfo->xfer_lock, flags);
+- bit_pos = find_first_zero_bit(minfo->xfer_alloc_table,
+- info->desc->max_msg);
+- if (bit_pos == info->desc->max_msg) {
++ bit_pos = find_first_zero_bit(minfo->xfer_alloc_table, minfo->max_msg);
++ if (bit_pos == minfo->max_msg) {
+ spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+ return ERR_PTR(-ENOMEM);
+ }
+@@ -602,32 +602,44 @@ int scmi_handle_put(const struct scmi_handle *handle)
+ }
+
+ static int __scmi_xfer_info_init(struct scmi_info *sinfo,
+- struct scmi_xfers_info *info)
++ struct scmi_xfers_info *info,
++ bool tx,
++ struct scmi_chan_info *base_cinfo)
+ {
+ int i;
+ struct scmi_xfer *xfer;
+ struct device *dev = sinfo->dev;
+ const struct scmi_desc *desc = sinfo->desc;
+
++ info->max_msg = desc->max_msg;
++
++ if (desc->ops->get_max_msg) {
++ int ret =
++ desc->ops->get_max_msg(tx, base_cinfo, &info->max_msg);
++
++ if (ret)
++ return ret;
++ }
++
+ /* Pre-allocated messages, no more than what hdr.seq can support */
+- if (WARN_ON(desc->max_msg >= MSG_TOKEN_MAX)) {
++ if (WARN_ON(info->max_msg >= MSG_TOKEN_MAX)) {
+ dev_err(dev, "Maximum message of %d exceeds supported %ld\n",
+- desc->max_msg, MSG_TOKEN_MAX);
++ info->max_msg, MSG_TOKEN_MAX);
+ return -EINVAL;
+ }
+
+- info->xfer_block = devm_kcalloc(dev, desc->max_msg,
++ info->xfer_block = devm_kcalloc(dev, info->max_msg,
+ sizeof(*info->xfer_block), GFP_KERNEL);
+ if (!info->xfer_block)
+ return -ENOMEM;
+
+- info->xfer_alloc_table = devm_kcalloc(dev, BITS_TO_LONGS(desc->max_msg),
++ info->xfer_alloc_table = devm_kcalloc(dev, BITS_TO_LONGS(info->max_msg),
+ sizeof(long), GFP_KERNEL);
+ if (!info->xfer_alloc_table)
+ return -ENOMEM;
+
+ /* Pre-initialize the buffer pointer to pre-allocated buffers */
+- for (i = 0, xfer = info->xfer_block; i < desc->max_msg; i++, xfer++) {
++ for (i = 0, xfer = info->xfer_block; i < info->max_msg; i++, xfer++) {
+ xfer->rx.buf = devm_kcalloc(dev, sizeof(u8), desc->max_msg_size,
+ GFP_KERNEL);
+ if (!xfer->rx.buf)
+@@ -644,10 +656,21 @@ static int __scmi_xfer_info_init(struct scmi_info *sinfo,
+
+ static int scmi_xfer_info_init(struct scmi_info *sinfo)
+ {
+- int ret = __scmi_xfer_info_init(sinfo, &sinfo->tx_minfo);
++ int ret;
++ struct scmi_chan_info *base_tx_cinfo;
++ struct scmi_chan_info *base_rx_cinfo;
++
++ base_tx_cinfo = idr_find(&sinfo->tx_idr, SCMI_PROTOCOL_BASE);
++ if (unlikely(!base_tx_cinfo))
++ return -EINVAL;
++
++ ret = __scmi_xfer_info_init(sinfo, &sinfo->tx_minfo, true,
++ base_tx_cinfo);
+
+- if (!ret && idr_find(&sinfo->rx_idr, SCMI_PROTOCOL_BASE))
+- ret = __scmi_xfer_info_init(sinfo, &sinfo->rx_minfo);
++ base_rx_cinfo = idr_find(&sinfo->rx_idr, SCMI_PROTOCOL_BASE);
++ if (!ret && base_rx_cinfo)
++ ret = __scmi_xfer_info_init(sinfo, &sinfo->rx_minfo, false,
++ base_rx_cinfo);
+
+ return ret;
+ }
--- /dev/null
+From 0771d1d96e6439c00497a521f8d2c9803f7e07e2 Mon Sep 17 00:00:00 2001
+From: Igor Skalkin <igor.skalkin@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:10 +0100
+Subject: [PATCH] firmware: arm_scmi: Add per message transport data
+
+The virtio transport in this patch series can be simplified by using the
+scmi_xfer tx/rx buffers for data exchange with the virtio device, and
+for saving the message state. But the virtio transport requires
+prepending a transport-specific header. Also, for data exchange using
+virtqueues, the tx and rx buffers should not overlap.
+
+The first step to solve the aforementioned issues is to add a
+transport-specific data pointer to scmi_xfer.
+
+Co-developed-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Igor Skalkin <igor.skalkin@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ drivers/firmware/arm_scmi/common.h | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
+index 9a8359ecd220..c998ec29018e 100644
+--- a/drivers/firmware/arm_scmi/common.h
++++ b/drivers/firmware/arm_scmi/common.h
+@@ -131,6 +131,7 @@ struct scmi_msg {
+ * buffer for the rx path as we use for the tx path.
+ * @done: command message transmit completion event
+ * @async_done: pointer to delayed response message received event completion
++ * @extra_data: Transport-specific private data pointer
+ */
+ struct scmi_xfer {
+ int transfer_id;
+@@ -139,6 +140,7 @@ struct scmi_xfer {
+ struct scmi_msg rx;
+ struct completion done;
+ struct completion *async_done;
++ void *extra_data;
+ };
+
+ void scmi_xfer_put(const struct scmi_handle *h, struct scmi_xfer *xfer);
--- /dev/null
+From fddb9bcd706ed3bb262f4f37707616dd06c7a4cc Mon Sep 17 00:00:00 2001
+From: Igor Skalkin <igor.skalkin@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:11 +0100
+Subject: [PATCH] firmware: arm_scmi: Add xfer_init_buffers transport op
+
+The virtio transport in this patch series can be simplified by using the
+scmi_xfer tx/rx buffers for data exchange with the virtio device, and
+for saving the message state. But the virtio transport requires
+prepending a transport-specific header. Also, for data exchange using
+virtqueues, the tx and rx buffers should not overlap.
+
+After the previous patch, this is the second and final step to enable
+the virtio transport to use the scmi_xfer buffers for data exchange.
+
+Add an optional op through which the transport can allocate the tx/rx
+buffers along with room for the prepended transport-specific headers.
+
+Co-developed-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Igor Skalkin <igor.skalkin@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ drivers/firmware/arm_scmi/common.h | 3 +++
+ drivers/firmware/arm_scmi/driver.c | 21 +++++++++++++++------
+ 2 files changed, 18 insertions(+), 6 deletions(-)
+
+diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
+index c998ec29018e..ae5db602e45d 100644
+--- a/drivers/firmware/arm_scmi/common.h
++++ b/drivers/firmware/arm_scmi/common.h
+@@ -208,6 +208,7 @@ struct scmi_chan_info {
+ * @get_max_msg: Optional callback to provide max_msg dynamically
+ * @max_msg: Maximum number of messages for the channel type (tx or rx)
+ * that can be pending simultaneously in the system
++ * @xfer_init_buffers: Callback to initialize buffers for scmi_xfer
+ * @send_message: Callback to send a message
+ * @mark_txdone: Callback to mark tx as done
+ * @fetch_response: Callback to fetch response
+@@ -222,6 +223,8 @@ struct scmi_transport_ops {
+ int (*chan_free)(int id, void *p, void *data);
+ int (*get_max_msg)(bool tx, struct scmi_chan_info *base_cinfo,
+ int *max_msg);
++ int (*xfer_init_buffers)(struct scmi_chan_info *cinfo,
++ struct scmi_xfer *xfer, int max_msg_size);
+ int (*send_message)(struct scmi_chan_info *cinfo,
+ struct scmi_xfer *xfer);
+ void (*mark_txdone)(struct scmi_chan_info *cinfo, int ret);
+diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
+index 5baa23789a49..27dd43dcff5b 100644
+--- a/drivers/firmware/arm_scmi/driver.c
++++ b/drivers/firmware/arm_scmi/driver.c
+@@ -640,12 +640,21 @@ static int __scmi_xfer_info_init(struct scmi_info *sinfo,
+
+ /* Pre-initialize the buffer pointer to pre-allocated buffers */
+ for (i = 0, xfer = info->xfer_block; i < info->max_msg; i++, xfer++) {
+- xfer->rx.buf = devm_kcalloc(dev, sizeof(u8), desc->max_msg_size,
+- GFP_KERNEL);
+- if (!xfer->rx.buf)
+- return -ENOMEM;
+-
+- xfer->tx.buf = xfer->rx.buf;
++ if (desc->ops->xfer_init_buffers) {
++ int ret = desc->ops->xfer_init_buffers(
++ base_cinfo, xfer, desc->max_msg_size);
++
++ if (ret)
++ return ret;
++ } else {
++ xfer->rx.buf = devm_kcalloc(dev, sizeof(u8),
++ desc->max_msg_size,
++ GFP_KERNEL);
++ if (!xfer->rx.buf)
++ return -ENOMEM;
++
++ xfer->tx.buf = xfer->rx.buf;
++ }
+ init_completion(&xfer->done);
+ }
+
--- /dev/null
+From f0d7ff1f10ab846bf32bae3b7d32bf95653954fa Mon Sep 17 00:00:00 2001
+From: Peter Hilber <peter.hilber@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:12 +0100
+Subject: [PATCH] firmware: arm_scmi: Add optional link_supplier() transport op
+
+For the scmi-virtio transport, it might not be possible to refer to the
+proper virtio device at device tree build time. Therefore, add an op
+which will allow scmi-virtio to dynamically link to the proper virtio
+device during probe.
+
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ drivers/firmware/arm_scmi/common.h | 2 ++
+ drivers/firmware/arm_scmi/driver.c | 6 ++++++
+ 2 files changed, 8 insertions(+)
+
+diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
+index ae5db602e45d..2f55ac71555a 100644
+--- a/drivers/firmware/arm_scmi/common.h
++++ b/drivers/firmware/arm_scmi/common.h
+@@ -202,6 +202,7 @@ struct scmi_chan_info {
+ /**
+ * struct scmi_transport_ops - Structure representing a SCMI transport ops
+ *
++ * @link_supplier: Optional callback to add link to a supplier device
+ * @chan_available: Callback to check if channel is available or not
+ * @chan_setup: Callback to allocate and setup a channel
+ * @chan_free: Callback to free a channel
+@@ -217,6 +218,7 @@ struct scmi_chan_info {
+ * @poll_done: Callback to poll transfer status
+ */
+ struct scmi_transport_ops {
++ int (*link_supplier)(struct device *dev);
+ bool (*chan_available)(struct device *dev, int idx);
+ int (*chan_setup)(struct scmi_chan_info *cinfo, struct device *dev,
+ bool tx);
+diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
+index 27dd43dcff5b..0b70f9ef9477 100644
+--- a/drivers/firmware/arm_scmi/driver.c
++++ b/drivers/firmware/arm_scmi/driver.c
+@@ -826,6 +826,12 @@ static int scmi_probe(struct platform_device *pdev)
+ handle->dev = info->dev;
+ handle->version = &info->version;
+
++ if (desc->ops->link_supplier) {
++ ret = desc->ops->link_supplier(dev);
++ if (ret)
++ return ret;
++ }
++
+ ret = scmi_txrx_setup(info, dev, SCMI_PROTOCOL_BASE);
+ if (ret)
+ return ret;
--- /dev/null
+From 9d5366d4765fb60cafa31c2b46cd80d284c847bb Mon Sep 17 00:00:00 2001
+From: Peter Hilber <peter.hilber@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:13 +0100
+Subject: [PATCH] firmware: arm_scmi: Add per-device transport private info
+
+The scmi-virtio transport will link a supplier device to the arm-scmi
+device in the link_supplier() op. The transport should then save a
+pointer to the linked device.
+
+To enable this, add a transport private info to the scmi_info. (The
+scmi_info is already reachable through the arm-scmi device driver_data.)
+
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ drivers/firmware/arm_scmi/common.h | 2 ++
+ drivers/firmware/arm_scmi/driver.c | 35 ++++++++++++++++++++++++++++++
+ 2 files changed, 37 insertions(+)
+
+diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
+index 2f55ac71555a..ec9fd7fce3c7 100644
+--- a/drivers/firmware/arm_scmi/common.h
++++ b/drivers/firmware/arm_scmi/common.h
+@@ -262,6 +262,8 @@ extern const struct scmi_desc scmi_mailbox_desc;
+ extern const struct scmi_desc scmi_smc_desc;
+ #endif
+
++int scmi_set_transport_info(struct device *dev, void *transport_info);
++void *scmi_get_transport_info(struct device *dev);
+ void scmi_rx_callback(struct scmi_chan_info *cinfo, u32 msg_hdr);
+ void scmi_free_channel(struct scmi_chan_info *cinfo, struct idr *idr, int id);
+
+diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
+index 0b70f9ef9477..93ce17bb4079 100644
+--- a/drivers/firmware/arm_scmi/driver.c
++++ b/drivers/firmware/arm_scmi/driver.c
+@@ -84,6 +84,7 @@ struct scmi_xfers_info {
+ * @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
++ * @transport_info: Transport private info
+ * @node: List head
+ * @users: Number of users of this instance
+ */
+@@ -97,6 +98,7 @@ struct scmi_info {
+ struct idr tx_idr;
+ struct idr rx_idr;
+ u8 *protocols_imp;
++ void *transport_info;
+ struct list_head node;
+ int users;
+ };
+@@ -315,6 +317,39 @@ void scmi_rx_callback(struct scmi_chan_info *cinfo, u32 msg_hdr)
+ }
+ }
+
++/**
++ * scmi_set_transport_info() - Set transport private info
++ *
++ * @dev: SCMI instance device
++ * @transport_info: transport private info
++ *
++ * Return: 0 on success, otherwise error.
++ */
++int scmi_set_transport_info(struct device *dev, void *transport_info)
++{
++ struct scmi_info *info = dev_get_drvdata(dev);
++
++ if (!info)
++ return -EBADR;
++
++ info->transport_info = transport_info;
++ return 0;
++}
++
++/**
++ * scmi_get_transport_info() - Get transport private info
++ *
++ * @dev: SCMI instance device
++ *
++ * Return: transport private info on success, otherwise NULL.
++ */
++void *scmi_get_transport_info(struct device *dev)
++{
++ struct scmi_info *info = dev_get_drvdata(dev);
++
++ return info ? info->transport_info : NULL;
++}
++
+ /**
+ * scmi_xfer_put() - Release a transmit message
+ *
--- /dev/null
+From c4b299105e74f7863b2aa63bd838e7762761629c Mon Sep 17 00:00:00 2001
+From: Peter Hilber <peter.hilber@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:14 +0100
+Subject: [PATCH] firmware: arm_scmi: Add is_scmi_protocol_device()
+
+The scmi-virtio transport driver will need to distinguish SCMI protocol
+devices from the SCMI instance device in the chan_setup() and
+chan_free() ops. Add this internal helper to be able to distinguish the
+two.
+
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ drivers/firmware/arm_scmi/bus.c | 5 +++++
+ drivers/firmware/arm_scmi/common.h | 2 ++
+ 2 files changed, 7 insertions(+)
+
+diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
+index 1377ec76a45d..4f19faafb2c5 100644
+--- a/drivers/firmware/arm_scmi/bus.c
++++ b/drivers/firmware/arm_scmi/bus.c
+@@ -108,6 +108,11 @@ static struct bus_type scmi_bus_type = {
+ .remove = scmi_dev_remove,
+ };
+
++bool is_scmi_protocol_device(struct device *dev)
++{
++ return dev->bus == &scmi_bus_type;
++}
++
+ int scmi_driver_register(struct scmi_driver *driver, struct module *owner,
+ const char *mod_name)
+ {
+diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
+index ec9fd7fce3c7..13c9ac176b23 100644
+--- a/drivers/firmware/arm_scmi/common.h
++++ b/drivers/firmware/arm_scmi/common.h
+@@ -158,6 +158,8 @@ int scmi_version_get(const struct scmi_handle *h, u8 protocol, u32 *version);
+ void scmi_setup_protocol_implemented(const struct scmi_handle *handle,
+ u8 *prot_imp);
+
++bool is_scmi_protocol_device(struct device *dev);
++
+ int scmi_base_protocol_init(struct scmi_handle *h);
+
+ int __init scmi_bus_init(void);
--- /dev/null
+From 592064dd36739ad5f3d885b9880ee1bc2d66e2df Mon Sep 17 00:00:00 2001
+From: Igor Skalkin <igor.skalkin@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:15 +0100
+Subject: [PATCH] dt-bindings: arm: Add virtio transport for SCMI
+
+Document the properties for arm,scmi-virtio compatible nodes. The
+backing virtio SCMI device is described in patch [1].
+
+[1] https://lists.oasis-open.org/archives/virtio-comment/202005/msg00096.html
+
+Co-developed-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Igor Skalkin <igor.skalkin@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ .../devicetree/bindings/arm/arm,scmi.txt | 35 +++++++++++++++++--
+ 1 file changed, 33 insertions(+), 2 deletions(-)
+
+diff --git a/Documentation/devicetree/bindings/arm/arm,scmi.txt b/Documentation/devicetree/bindings/arm/arm,scmi.txt
+index 55deb68230eb..6ded49d82773 100644
+--- a/Documentation/devicetree/bindings/arm/arm,scmi.txt
++++ b/Documentation/devicetree/bindings/arm/arm,scmi.txt
+@@ -13,6 +13,9 @@ the device tree.
+ Required properties:
+
+ The scmi node with the following properties shall be under the /firmware/ node.
++Some properties are specific to a transport type.
++
++shmem-based transports (mailbox, smc/hvc):
+
+ - compatible : shall be "arm,scmi" or "arm,scmi-smc" for smc/hvc transports
+ - mboxes: List of phandle and mailbox channel specifiers. It should contain
+@@ -21,6 +24,15 @@ The scmi node with the following properties shall be under the /firmware/ node.
+ supported.
+ - shmem : List of phandle pointing to the shared memory(SHM) area as per
+ generic mailbox client binding.
++
++Virtio transport:
++
++- compatible : shall be "arm,scmi-virtio".
++
++The virtio transport only supports a single device.
++
++Additional required properties:
++
+ - #address-cells : should be '1' if the device has sub-nodes, maps to
+ protocol identifier for a given sub-node.
+ - #size-cells : should be '0' as 'reg' property doesn't have any size
+@@ -42,7 +54,8 @@ Each protocol supported shall have a sub-node with corresponding compatible
+ as described in the following sections. If the platform supports dedicated
+ communication channel for a particular protocol, the 3 properties namely:
+ mboxes, mbox-names and shmem shall be present in the sub-node corresponding
+-to that protocol.
++to that protocol. The virtio transport does not support dedicated communication
++channels.
+
+ Clock/Performance bindings for the clocks/OPPs based on SCMI Message Protocol
+ ------------------------------------------------------------
+@@ -106,7 +119,8 @@ Required sub-node properties:
+ [4] Documentation/devicetree/bindings/sram/sram.yaml
+ [5] Documentation/devicetree/bindings/reset/reset.txt
+
+-Example:
++Example (mailbox transport):
++----------------------------
+
+ sram@50000000 {
+ compatible = "mmio-sram";
+@@ -195,3 +209,20 @@ thermal-zones {
+ ...
+ };
+ };
++
++Example (virtio transport):
++---------------------------
++
++virtio_mmio@4b001000 {
++ compatible = "virtio,mmio";
++ ...
++};
++
++firmware {
++ ...
++ scmi {
++ compatible = "arm,scmi-virtio";
++ ...
++
++The rest is similar to the mailbox transport example, when omitting the
++mailbox/shmem-specific properties.
--- /dev/null
+From 7b9f3fe0766d6d36ca7465e54754df51ca175079 Mon Sep 17 00:00:00 2001
+From: Igor Skalkin <igor.skalkin@opensynergy.com>
+Date: Thu, 5 Nov 2020 22:21:16 +0100
+Subject: [PATCH] firmware: arm_scmi: Add virtio transport
+
+This transport enables accessing an SCMI platform as a virtio device.
+
+Implement an SCMI virtio driver according to the virtio SCMI device spec
+patch v5 [1]. Virtio device id 32 has been reserved for the SCMI device
+[2].
+
+The virtio transport has one tx channel (virtio cmdq, A2P channel) and
+at most one rx channel (virtio eventq, P2A channel).
+
+The following feature bit defined in [1] is not implemented:
+VIRTIO_SCMI_F_SHARED_MEMORY.
+
+After the preparatory patches, implement the virtio transport as
+paraphrased:
+
+Only support a single arm-scmi device (which is consistent with the SCMI
+spec). Call scmi-virtio init from arm-scmi module init. During the
+arm-scmi probing, link to the first probed scmi-virtio device. Defer
+arm-scmi probing if no scmi-virtio device is bound yet.
+
+Use the scmi_xfer tx/rx buffers for data exchange with the virtio device
+in order to avoid redundant maintenance of additional buffers. Allocate
+the buffers in the SCMI transport, and prepend room for a small header
+used by the virtio transport to the tx/rx buffers.
+
+For simplicity, restrict the number of messages which can be pending
+simultaneously according to the virtqueue capacity. (The virtqueue sizes
+are negotiated with the virtio device.)
+
+As soon as rx channel message buffers are allocated or have been read
+out by the arm-scmi driver, feed them to the virtio device.
+
+Since some virtio devices may not have the short response time exhibited
+by SCMI platforms using other transports, set a generous response
+timeout.
+
+Limitations:
+
+Do not adjust the other SCMI timeouts for delayed response and polling
+for now, since these timeouts are only relevant in special cases which
+are not yet deemed relevant for this transport.
+
+To do (as discussed in the cover letter):
+
+- Avoid re-use of buffers still being used by the virtio device on
+ timeouts.
+
+- Avoid race conditions on receiving messages during/after channel free
+ on driver probe failure or remove.
+
+[1] https://lists.oasis-open.org/archives/virtio-comment/202005/msg00096.html
+[2] https://www.oasis-open.org/committees/ballot.php?id=3496
+
+Co-developed-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
+Signed-off-by: Igor Skalkin <igor.skalkin@opensynergy.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ MAINTAINERS | 1 +
+ drivers/firmware/Kconfig | 12 +-
+ drivers/firmware/arm_scmi/Makefile | 1 +
+ drivers/firmware/arm_scmi/common.h | 14 +
+ drivers/firmware/arm_scmi/driver.c | 11 +
+ drivers/firmware/arm_scmi/virtio.c | 493 +++++++++++++++++++++++++++++
+ include/uapi/linux/virtio_ids.h | 1 +
+ include/uapi/linux/virtio_scmi.h | 41 +++
+ 8 files changed, 573 insertions(+), 1 deletion(-)
+ create mode 100644 drivers/firmware/arm_scmi/virtio.c
+ create mode 100644 include/uapi/linux/virtio_scmi.h
+
+diff --git a/MAINTAINERS b/MAINTAINERS
+index 49772b741967..d223a5c3f465 100644
+--- a/MAINTAINERS
++++ b/MAINTAINERS
+@@ -16973,6 +16973,7 @@ F: drivers/firmware/arm_scpi.c
+ F: drivers/reset/reset-scmi.c
+ F: include/linux/sc[mp]i_protocol.h
+ F: include/trace/events/scmi.h
++F: include/uapi/linux/virtio_scmi.h
+
+ SYSTEM RESET/SHUTDOWN DRIVERS
+ M: Sebastian Reichel <sre@kernel.org>
+diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
+index 30a85d38d0c0..82e97904bcae 100644
+--- a/drivers/firmware/Kconfig
++++ b/drivers/firmware/Kconfig
+@@ -9,7 +9,7 @@ menu "Firmware Drivers"
+ config ARM_SCMI_PROTOCOL
+ tristate "ARM System Control and Management Interface (SCMI) Message Protocol"
+ depends on ARM || ARM64 || COMPILE_TEST
+- depends on ARM_SCMI_HAVE_SHMEM
++ depends on ARM_SCMI_HAVE_SHMEM || VIRTIO_SCMI
+ help
+ ARM System Control and Management Interface (SCMI) protocol is a
+ set of operating system-independent software interfaces that are
+@@ -34,6 +34,16 @@ config ARM_SCMI_HAVE_SHMEM
+ This declares whether a shared memory based transport for SCMI is
+ available.
+
++config VIRTIO_SCMI
++ bool "Virtio transport for SCMI"
++ default n
++ depends on VIRTIO
++ help
++ This enables the virtio based transport for SCMI.
++
++ If you want to use the ARM SCMI protocol between the virtio guest and
++ a host providing a virtio SCMI device, answer Y.
++
+ config ARM_SCMI_POWER_DOMAIN
+ tristate "SCMI power domain driver"
+ depends on ARM_SCMI_PROTOCOL || (COMPILE_TEST && OF)
+diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
+index 3cc7fa40a464..25caea5e1969 100644
+--- a/drivers/firmware/arm_scmi/Makefile
++++ b/drivers/firmware/arm_scmi/Makefile
+@@ -4,6 +4,7 @@ scmi-driver-y = driver.o notify.o
+ scmi-transport-$(CONFIG_ARM_SCMI_HAVE_SHMEM) = shmem.o
+ scmi-transport-$(CONFIG_MAILBOX) += mailbox.o
+ scmi-transport-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smc.o
++scmi-transport-$(CONFIG_VIRTIO_SCMI) += virtio.o
+ scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o
+ scmi-module-objs := $(scmi-bus-y) $(scmi-driver-y) $(scmi-protocols-y) \
+ $(scmi-transport-y)
+diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
+index 13c9ac176b23..b46dfe84e78b 100644
+--- a/drivers/firmware/arm_scmi/common.h
++++ b/drivers/firmware/arm_scmi/common.h
+@@ -165,6 +165,17 @@ int scmi_base_protocol_init(struct scmi_handle *h);
+ int __init scmi_bus_init(void);
+ void __exit scmi_bus_exit(void);
+
++#ifdef CONFIG_VIRTIO_SCMI
++int __init virtio_scmi_init(void);
++void __exit virtio_scmi_exit(void);
++#else
++static inline int __init virtio_scmi_init(void)
++{
++ return 0;
++}
++#define virtio_scmi_exit() do { } while (0)
++#endif
++
+ #define DECLARE_SCMI_REGISTER_UNREGISTER(func) \
+ int __init scmi_##func##_register(void); \
+ void __exit scmi_##func##_unregister(void)
+@@ -263,6 +274,9 @@ extern const struct scmi_desc scmi_mailbox_desc;
+ #ifdef CONFIG_HAVE_ARM_SMCCC
+ extern const struct scmi_desc scmi_smc_desc;
+ #endif
++#ifdef CONFIG_VIRTIO_SCMI
++extern const struct scmi_desc scmi_virtio_desc;
++#endif
+
+ int scmi_set_transport_info(struct device *dev, void *transport_info);
+ void *scmi_get_transport_info(struct device *dev);
+diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
+index 93ce17bb4079..540a55285349 100644
+--- a/drivers/firmware/arm_scmi/driver.c
++++ b/drivers/firmware/arm_scmi/driver.c
+@@ -996,6 +996,9 @@ static const struct of_device_id scmi_of_match[] = {
+ #endif
+ #ifdef CONFIG_HAVE_ARM_SMCCC_DISCOVERY
+ { .compatible = "arm,scmi-smc", .data = &scmi_smc_desc},
++#endif
++#ifdef CONFIG_VIRTIO_SCMI
++ { .compatible = "arm,scmi-virtio", .data = &scmi_virtio_desc},
+ #endif
+ { /* Sentinel */ },
+ };
+@@ -1014,8 +1017,14 @@ static struct platform_driver scmi_driver = {
+
+ static int __init scmi_driver_init(void)
+ {
++ int ret;
++
+ scmi_bus_init();
+
++ ret = virtio_scmi_init();
++ if (ret)
++ return ret;
++
+ scmi_clock_register();
+ scmi_perf_register();
+ scmi_power_register();
+@@ -1038,6 +1047,8 @@ static void __exit scmi_driver_exit(void)
+ scmi_sensors_unregister();
+ scmi_system_unregister();
+
++ virtio_scmi_exit();
++
+ platform_driver_unregister(&scmi_driver);
+ }
+ module_exit(scmi_driver_exit);
+diff --git a/drivers/firmware/arm_scmi/virtio.c b/drivers/firmware/arm_scmi/virtio.c
+new file mode 100644
+index 000000000000..f70aa72f34f1
+--- /dev/null
++++ b/drivers/firmware/arm_scmi/virtio.c
+@@ -0,0 +1,493 @@
++// SPDX-License-Identifier: GPL-2.0
++/*
++ * Virtio Transport driver for Arm System Control and Management Interface
++ * (SCMI).
++ *
++ * Copyright (C) 2020 OpenSynergy.
++ */
++
++/**
++ * DOC: Theory of Operation
++ *
++ * The scmi-virtio transport implements a driver for the virtio SCMI device
++ * proposed in virtio spec patch v5[1].
++ *
++ * There is one tx channel (virtio cmdq, A2P channel) and at most one rx
++ * channel (virtio eventq, P2A channel). Each channel is implemented through a
++ * virtqueue. Access to each virtqueue is protected by a spinlock.
++ *
++ * This SCMI transport uses the scmi_xfer tx/rx buffers for data exchange with
++ * the virtio device to avoid maintenance of additional buffers.
++ *
++ * [1] https://lists.oasis-open.org/archives/virtio-comment/202005/msg00096.html
++ */
++
++#include <linux/errno.h>
++#include <linux/of.h>
++#include <linux/of_platform.h>
++#include <linux/platform_device.h>
++#include <linux/module.h>
++#include <linux/slab.h>
++#include <linux/virtio.h>
++#include <linux/virtio_config.h>
++#include <uapi/linux/virtio_ids.h>
++#include <uapi/linux/virtio_scmi.h>
++
++#include "common.h"
++
++#define VIRTIO_SCMI_MAX_MSG_SIZE 128 /* Value may be increased. */
++#define DESCR_PER_TX_MSG 2
++
++struct scmi_vio_channel {
++ spinlock_t lock;
++ struct virtqueue *vqueue;
++ struct scmi_chan_info *cinfo;
++ u8 is_rx;
++};
++
++union virtio_scmi_input {
++ __virtio32 hdr;
++ struct virtio_scmi_response response;
++ struct virtio_scmi_notification notification;
++};
++
++struct scmi_vio_msg {
++ struct virtio_scmi_request *request;
++ union virtio_scmi_input *input;
++ u8 completed;
++};
++
++static int scmi_vio_populate_vq_rx(struct scmi_vio_channel *vioch,
++ struct scmi_xfer *xfer)
++{
++ struct scatterlist sg_in;
++ struct scmi_vio_msg *msg = xfer->extra_data;
++ int rc;
++
++ msg->completed = false;
++
++ sg_init_one(&sg_in, msg->input,
++ sizeof(*msg->input) + VIRTIO_SCMI_MAX_MSG_SIZE);
++
++ rc = virtqueue_add_inbuf(vioch->vqueue, &sg_in, 1, xfer, GFP_ATOMIC);
++ if (rc)
++ dev_err(vioch->cinfo->dev, "%s() rc=%d\n", __func__, rc);
++ else
++ virtqueue_kick(vioch->vqueue);
++
++ return rc;
++}
++
++static void scmi_vio_complete_cb(struct virtqueue *vqueue)
++{
++ struct scmi_vio_channel *vioch = vqueue->priv;
++ unsigned long iflags;
++ unsigned int length;
++
++ spin_lock_irqsave(&vioch->lock, iflags);
++
++ do {
++ struct scmi_xfer *xfer;
++
++ virtqueue_disable_cb(vqueue);
++
++ while ((xfer = virtqueue_get_buf(vqueue, &length))) {
++ struct scmi_vio_msg *msg = xfer->extra_data;
++ u32 msg_hdr =
++ virtio32_to_cpu(vqueue->vdev, msg->input->hdr);
++ u8 msg_type = MSG_XTRACT_TYPE(msg_hdr);
++
++ if (!vioch->is_rx) { /* tx queue response */
++ msg->completed = true;
++ xfer->rx.len =
++ length - sizeof(msg->input->response);
++ if (!xfer->hdr.poll_completion)
++ scmi_rx_callback(vioch->cinfo, msg_hdr);
++ continue;
++ }
++
++ /* rx queue - notification or delayed response */
++ switch (msg_type) {
++ case MSG_TYPE_NOTIFICATION:
++ xfer->rx.len = length -
++ sizeof(msg->input->notification);
++ xfer->rx.buf = msg->input->notification.data;
++ break;
++ case MSG_TYPE_DELAYED_RESP:
++ xfer->rx.len =
++ length - sizeof(msg->input->response);
++ xfer->rx.buf = msg->input->response.data;
++ break;
++ default:
++ dev_warn_once(vioch->cinfo->dev,
++ "rx: unknown message_type %d\n",
++ msg_type);
++ scmi_vio_populate_vq_rx(vioch, xfer);
++ continue;
++ }
++
++ scmi_rx_callback(vioch->cinfo, msg_hdr);
++ scmi_vio_populate_vq_rx(vioch, xfer);
++ }
++
++ if (unlikely(virtqueue_is_broken(vqueue)))
++ break;
++ } while (!virtqueue_enable_cb(vqueue));
++
++ spin_unlock_irqrestore(&vioch->lock, iflags);
++}
++
++static const char *const scmi_vio_vqueue_names[] = { "tx", "rx" };
++
++static vq_callback_t *scmi_vio_complete_callbacks[] = {
++ scmi_vio_complete_cb,
++ scmi_vio_complete_cb
++};
++
++static int scmi_vio_match_any_dev(struct device *dev, const void *data)
++{
++ (void)dev;
++ (void)data;
++
++ return 1;
++}
++
++static struct virtio_driver virtio_scmi_driver; /* Forward declaration */
++
++static int virtio_link_supplier(struct device *dev)
++{
++ struct device *vdev = driver_find_device(
++ &virtio_scmi_driver.driver, NULL, NULL, scmi_vio_match_any_dev);
++
++ if (!vdev) {
++ dev_notice_once(
++ dev,
++ "Deferring probe after not finding a bound scmi-virtio device\n");
++ return -EPROBE_DEFER;
++ }
++
++ /*
++ * Add plain device link for completeness. It might have no effect
++ * beyond sysfs.
++ */
++ if (!device_link_add(dev, vdev, DL_FLAG_AUTOREMOVE_CONSUMER)) {
++ put_device(vdev);
++ dev_err(dev, "Adding link to supplier virtio device failed\n");
++ return -ECANCELED;
++ }
++
++ put_device(vdev);
++ return scmi_set_transport_info(dev, dev_to_virtio(vdev));
++}
++
++static bool virtio_chan_available(struct device *dev, int idx)
++{
++ struct virtio_device *vdev;
++ struct scmi_vio_channel **vioch;
++
++ /* scmi-virtio doesn't support per-protocol channels */
++ if (is_scmi_protocol_device(dev))
++ return false;
++
++ vdev = scmi_get_transport_info(dev);
++ if (!vdev)
++ return false;
++
++ vioch = vdev->priv;
++ if (!vioch)
++ return false;
++
++ return vioch[idx] && vioch[idx]->vqueue;
++}
++
++static int virtio_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
++ bool tx)
++{
++ struct virtio_device *vdev;
++ struct scmi_vio_channel **vioch;
++ int vioch_index = tx ? VIRTIO_SCMI_VQ_TX : VIRTIO_SCMI_VQ_RX;
++
++ /* scmi-virtio doesn't support per-protocol channels */
++ if (is_scmi_protocol_device(dev))
++ return -1;
++
++ vdev = scmi_get_transport_info(dev);
++ if (!vdev)
++ return -1;
++
++ vioch = vdev->priv;
++ if (!vioch) {
++ dev_err(dev, "Data from scmi-virtio probe not found\n");
++ return -1;
++ }
++ cinfo->transport_info = vioch[vioch_index];
++ vioch[vioch_index]->cinfo = cinfo;
++
++ return 0;
++}
++
++static int virtio_chan_free(int id, void *p, void *data)
++{
++ struct scmi_chan_info *cinfo = p;
++ struct scmi_vio_channel *vioch = cinfo->transport_info;
++
++ if (vioch) {
++ cinfo->transport_info = NULL;
++ kfree(vioch);
++ }
++
++ scmi_free_channel(cinfo, data, id);
++ return 0;
++}
++
++static int virtio_get_max_msg(bool tx, struct scmi_chan_info *base_cinfo,
++ int *max_msg)
++{
++ struct scmi_vio_channel *vioch = base_cinfo->transport_info;
++
++ *max_msg = virtqueue_get_vring_size(vioch->vqueue);
++
++ /* Tx messages need multiple descriptors. */
++ if (tx)
++ *max_msg /= DESCR_PER_TX_MSG;
++
++ if (*max_msg > MSG_TOKEN_MAX) {
++ dev_notice(
++ base_cinfo->dev,
++ "Only %ld messages can be pending simultaneously, while the virtqueue could hold %d\n",
++ MSG_TOKEN_MAX, *max_msg);
++ *max_msg = MSG_TOKEN_MAX;
++ }
++
++ return 0;
++}
++
++static int virtio_xfer_init_buffers(struct scmi_chan_info *cinfo,
++ struct scmi_xfer *xfer, int max_msg_size)
++{
++ struct scmi_vio_channel *vioch = cinfo->transport_info;
++ struct scmi_vio_msg *msg;
++
++ msg = devm_kzalloc(cinfo->dev, sizeof(*msg), GFP_KERNEL);
++ if (!msg)
++ return -ENOMEM;
++
++ xfer->extra_data = msg;
++
++ if (vioch->is_rx) {
++ int rc;
++ unsigned long iflags;
++
++ msg->input = devm_kzalloc(cinfo->dev,
++ sizeof(*msg->input) + max_msg_size,
++ GFP_KERNEL);
++ if (!msg->input)
++ return -ENOMEM;
++
++ /*
++ * xfer->rx.buf will be set to notification or delayed response
++ * specific values in the receive callback, according to the
++ * type of the received message.
++ */
++
++ spin_lock_irqsave(&vioch->lock, iflags);
++ rc = scmi_vio_populate_vq_rx(vioch, xfer);
++ spin_unlock_irqrestore(&vioch->lock, iflags);
++ if (rc)
++ return rc;
++ } else {
++ msg->request =
++ devm_kzalloc(cinfo->dev,
++ sizeof(*msg->request) + max_msg_size,
++ GFP_KERNEL);
++ if (!msg->request)
++ return -ENOMEM;
++
++ xfer->tx.buf = msg->request->data;
++
++ msg->input = devm_kzalloc(
++ cinfo->dev, sizeof(msg->input->response) + max_msg_size,
++ GFP_KERNEL);
++ if (!msg->input)
++ return -ENOMEM;
++
++ xfer->rx.buf = msg->input->response.data;
++ }
++
++ return 0;
++}
++
++static int scmi_vio_send(struct scmi_vio_channel *vioch, struct scmi_xfer *xfer)
++{
++ struct scatterlist sg_out;
++ struct scatterlist sg_in;
++ struct scatterlist *sgs[DESCR_PER_TX_MSG] = { &sg_out, &sg_in };
++ struct scmi_vio_msg *msg = xfer->extra_data;
++ unsigned long iflags;
++ int rc;
++
++ msg->completed = false;
++
++ sg_init_one(&sg_out, msg->request,
++ sizeof(*msg->request) + xfer->tx.len);
++ sg_init_one(&sg_in, &msg->input->response,
++ sizeof(msg->input->response) + xfer->rx.len);
++
++ spin_lock_irqsave(&vioch->lock, iflags);
++ rc = virtqueue_add_sgs(vioch->vqueue, sgs, 1, 1, xfer, GFP_ATOMIC);
++ if (rc)
++ dev_err(vioch->cinfo->dev, "%s() rc=%d\n", __func__, rc);
++ else
++ virtqueue_kick(vioch->vqueue);
++ spin_unlock_irqrestore(&vioch->lock, iflags);
++
++ return rc;
++}
++
++static int virtio_send_message(struct scmi_chan_info *cinfo,
++ struct scmi_xfer *xfer)
++{
++ uint32_t hdr;
++ struct scmi_vio_channel *vioch = cinfo->transport_info;
++ struct virtio_device *vdev = vioch->vqueue->vdev;
++ struct scmi_vio_msg *msg = xfer->extra_data;
++
++ hdr = pack_scmi_header(&xfer->hdr);
++
++ msg->request->hdr = cpu_to_virtio32(vdev, hdr);
++
++ return scmi_vio_send(vioch, xfer);
++}
++
++static void virtio_fetch_response(struct scmi_chan_info *cinfo,
++ struct scmi_xfer *xfer)
++{
++ struct scmi_vio_channel *vioch = cinfo->transport_info;
++ struct scmi_vio_msg *msg = xfer->extra_data;
++
++ xfer->hdr.status = virtio32_to_cpu(vioch->vqueue->vdev,
++ msg->input->response.status);
++}
++
++static void dummy_fetch_notification(struct scmi_chan_info *cinfo,
++ size_t max_len, struct scmi_xfer *xfer)
++{
++ (void)cinfo;
++ (void)max_len;
++ (void)xfer;
++}
++
++static void dummy_clear_channel(struct scmi_chan_info *cinfo)
++{
++ (void)cinfo;
++}
++
++static bool virtio_poll_done(struct scmi_chan_info *cinfo,
++ struct scmi_xfer *xfer)
++{
++ struct scmi_vio_channel *vioch = cinfo->transport_info;
++ struct scmi_vio_msg *msg = xfer->extra_data;
++ unsigned long iflags;
++ bool completed;
++
++ spin_lock_irqsave(&vioch->lock, iflags);
++ completed = msg->completed;
++ spin_unlock_irqrestore(&vioch->lock, iflags);
++
++ return completed;
++}
++
++static const struct scmi_transport_ops scmi_virtio_ops = {
++ .link_supplier = virtio_link_supplier,
++ .chan_available = virtio_chan_available,
++ .chan_setup = virtio_chan_setup,
++ .chan_free = virtio_chan_free,
++ .get_max_msg = virtio_get_max_msg,
++ .send_message = virtio_send_message,
++ .fetch_response = virtio_fetch_response,
++ .fetch_notification = dummy_fetch_notification,
++ .clear_channel = dummy_clear_channel,
++ .poll_done = virtio_poll_done,
++ .xfer_init_buffers = virtio_xfer_init_buffers,
++};
++
++const struct scmi_desc scmi_virtio_desc = {
++ .ops = &scmi_virtio_ops,
++ .max_rx_timeout_ms = 60000, /* for non-realtime virtio devices */
++ .max_msg = 0, /* overridden by virtio_get_max_msg() */
++ .max_msg_size = VIRTIO_SCMI_MAX_MSG_SIZE,
++};
++
++static int scmi_vio_probe(struct virtio_device *vdev)
++{
++ struct device *dev = &vdev->dev;
++ struct scmi_vio_channel **vioch;
++ bool have_vq_rx;
++ int vq_cnt;
++ int i;
++ struct virtqueue *vqs[VIRTIO_SCMI_VQ_MAX_CNT];
++
++ vioch = devm_kcalloc(dev, VIRTIO_SCMI_VQ_MAX_CNT, sizeof(*vioch),
++ GFP_KERNEL);
++ if (!vioch)
++ return -ENOMEM;
++
++ have_vq_rx = virtio_has_feature(vdev, VIRTIO_SCMI_F_P2A_CHANNELS);
++ vq_cnt = have_vq_rx ? VIRTIO_SCMI_VQ_MAX_CNT : 1;
++
++ for (i = 0; i < vq_cnt; i++) {
++ vioch[i] = devm_kzalloc(dev, sizeof(**vioch), GFP_KERNEL);
++ if (!vioch[i])
++ return -ENOMEM;
++ }
++
++ if (have_vq_rx)
++ vioch[VIRTIO_SCMI_VQ_RX]->is_rx = true;
++
++ if (virtio_find_vqs(vdev, vq_cnt, vqs, scmi_vio_complete_callbacks,
++ scmi_vio_vqueue_names, NULL)) {
++ dev_err(dev, "Failed to get %d virtqueue(s)\n", vq_cnt);
++ return -1;
++ }
++ dev_info(dev, "Found %d virtqueue(s)\n", vq_cnt);
++
++ for (i = 0; i < vq_cnt; i++) {
++ spin_lock_init(&vioch[i]->lock);
++ vioch[i]->vqueue = vqs[i];
++ vioch[i]->vqueue->priv = vioch[i];
++ }
++
++ vdev->priv = vioch;
++
++ virtio_device_ready(vdev);
++
++ return 0;
++}
++
++static unsigned int features[] = {
++ VIRTIO_SCMI_F_P2A_CHANNELS,
++};
++
++static const struct virtio_device_id id_table[] = {
++ { VIRTIO_ID_SCMI, VIRTIO_DEV_ANY_ID },
++ { 0 }
++};
++
++static struct virtio_driver virtio_scmi_driver = {
++ .driver.name = "scmi-virtio",
++ .driver.owner = THIS_MODULE,
++ .feature_table = features,
++ .feature_table_size = ARRAY_SIZE(features),
++ .id_table = id_table,
++ .probe = scmi_vio_probe,
++};
++
++int __init virtio_scmi_init(void)
++{
++ return register_virtio_driver(&virtio_scmi_driver);
++}
++
++void __exit virtio_scmi_exit(void)
++{
++ unregister_virtio_driver(&virtio_scmi_driver);
++}
+diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
+index bc740d6d2259..287daba2abdb 100644
+--- a/include/uapi/linux/virtio_ids.h
++++ b/include/uapi/linux/virtio_ids.h
+@@ -49,5 +49,6 @@
+ #define VIRTIO_ID_FS 26 /* virtio filesystem */
+ #define VIRTIO_ID_PMEM 27 /* virtio pmem */
+ #define VIRTIO_ID_MAC80211_HWSIM 29 /* virtio mac80211-hwsim */
++#define VIRTIO_ID_SCMI 32 /* virtio SCMI */
+
+ #endif /* _LINUX_VIRTIO_IDS_H */
+diff --git a/include/uapi/linux/virtio_scmi.h b/include/uapi/linux/virtio_scmi.h
+new file mode 100644
+index 000000000000..9f21b3dbbfe2
+--- /dev/null
++++ b/include/uapi/linux/virtio_scmi.h
+@@ -0,0 +1,41 @@
++/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */
++/*
++ * Copyright (C) 2020 OpenSynergy GmbH
++ */
++
++#ifndef _UAPI_LINUX_VIRTIO_SCMI_H
++#define _UAPI_LINUX_VIRTIO_SCMI_H
++
++#include <linux/virtio_types.h>
++
++/* Feature bits */
++
++/* Device implements some SCMI notifications, or delayed responses. */
++#define VIRTIO_SCMI_F_P2A_CHANNELS 0
++
++/* Device implements any SCMI statistics shared memory region */
++#define VIRTIO_SCMI_F_SHARED_MEMORY 1
++
++/* Virtqueues */
++
++#define VIRTIO_SCMI_VQ_TX 0 /* cmdq */
++#define VIRTIO_SCMI_VQ_RX 1 /* eventq */
++#define VIRTIO_SCMI_VQ_MAX_CNT 2
++
++struct virtio_scmi_request {
++ __virtio32 hdr;
++ __u8 data[];
++};
++
++struct virtio_scmi_response {
++ __virtio32 hdr;
++ __virtio32 status;
++ __u8 data[];
++};
++
++struct virtio_scmi_notification {
++ __virtio32 hdr;
++ __u8 data[];
++};
++
++#endif /* _UAPI_LINUX_VIRTIO_SCMI_H */
--- /dev/null
+# virtio SCMI
+SRC_URI += " \
+ file://virtio-scmi/0001-firmware-arm_scmi-smccc-mailbox-Make-shmem-based-tra.patch \
+ file://virtio-scmi/0002-firmware-arm_scmi-Document-that-max_msg-is-a-per-cha.patch \
+ file://virtio-scmi/0003-firmware-arm_scmi-Add-op-to-override-max-message.patch \
+ file://virtio-scmi/0004-firmware-arm_scmi-Add-per-message-transport-data.patch \
+ file://virtio-scmi/0005-firmware-arm_scmi-Add-xfer_init_buffers-transport-op.patch \
+ file://virtio-scmi/0006-firmware-arm_scmi-Add-optional-link_supplier-transpo.patch \
+ file://virtio-scmi/0007-firmware-arm_scmi-Add-per-device-transport-private-i.patch \
+ file://virtio-scmi/0008-firmware-arm_scmi-Add-is_scmi_protocol_device.patch \
+ file://virtio-scmi/0009-dt-bindings-arm-Add-virtio-transport-for-SCMI.patch \
+ file://virtio-scmi/0010-firmware-arm_scmi-Add-virtio-transport.patch \
+"
Code Review / AGL / meta-agl-devel.git / commitdiff