[PATCH v7 1/2] dt-bindings: arm: Add OP-TEE transport for SCMI

[PATCH v7 1/2] dt-bindings: arm: Add OP-TEE transport for SCMI

[Etienne Carriere]

Introduce compatible "linaro,scmi-optee" for SCMI transport channel
based on an OP-TEE service invocation. The compatible mandates a
channel ID defined with property "linaro,optee-channel-id".

Cc: devicetree@vger.kernel.org
Cc: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
---
Changes since v6:
 - Remove maxItems from linaro,optee-channel-id description

No change since v5

Changes since v4:
 - Fix sram node name in DTS example: s/-shm-/-sram-/

Changes since v3:
 - Add description for linaro,optee-channel-id in patternProperties
   specifying protocol can optionaly define a dedicated channel id.
 - Fix DTS example (duplicated phandles issue, subnodes ordering)
 - Fix typo in DTS example and description comments.

Changes since v2:
 - Define mandatory property linaro,optee-channel-id
 - Rebased on yaml description file

Changes since v1:
 - Removed modification regarding mboxes property description.
---
 .../bindings/firmware/arm,scmi.yaml           | 65 +++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
index 5c4c6782e052..eae15df36eef 100644
--- a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
+++ b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
@@ -38,6 +38,9 @@ properties:
                      The virtio transport only supports a single device.
         items:
           - const: arm,scmi-virtio
+      - description: SCMI compliant firmware with OP-TEE transport
+        items:
+          - const: linaro,scmi-optee
 
   interrupts:
     description:
@@ -83,6 +86,11 @@ properties:
     description:
       SMC id required when using smc or hvc transports
 
+  linaro,optee-channel-id:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Channel specifier required when using OP-TEE transport.
+
   protocol@11:
     type: object
     properties:
@@ -195,6 +203,12 @@ patternProperties:
         minItems: 1
         maxItems: 2
 
+      linaro,optee-channel-id:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description:
+          Channel specifier required when using OP-TEE transport and
+          protocol has a dedicated communication channel.
+
     required:
       - reg
 
@@ -226,6 +240,16 @@ else:
       - arm,smc-id
       - shmem
 
+  else:
+    if:
+      properties:
+        compatible:
+          contains:
+            const: linaro,scmi-optee
+    then:
+      required:
+        - linaro,optee-channel-id
+
 examples:
   - |
     firmware {
@@ -340,7 +364,48 @@ examples:
                 reg = <0x11>;
                 #power-domain-cells = <1>;
             };
+        };
+    };
+
+  - |
+    firmware {
+        scmi {
+            compatible = "linaro,scmi-optee";
+            linaro,optee-channel-id = <0>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            scmi_dvfs1: protocol@13 {
+                reg = <0x13>;
+                linaro,optee-channel-id = <1>;
+                shmem = <&cpu_optee_lpri0>;
+                #clock-cells = <1>;
+            };
+
+            scmi_clk0: protocol@14 {
+                reg = <0x14>;
+                #clock-cells = <1>;
+            };
+        };
+    };
 
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        sram@51000000 {
+            compatible = "mmio-sram";
+            reg = <0x0 0x51000000 0x0 0x10000>;
+
+            #address-cells = <1>;
+            #size-cells = <1>;
+            ranges = <0 0x0 0x51000000 0x10000>;
+
+            cpu_optee_lpri0: optee-sram-section@0 {
+                compatible = "arm,scmi-shmem";
+                reg = <0x0 0x80>;
+            };
         };
     };
 
-- 
2.17.1

[PATCH v7 2/2] firmware: arm_scmi: Add optee transport

[Etienne Carriere]

Add a new transport channel to the SCMI firmware interface driver for
SCMI message exchange based on optee transport channel. The optee
transport is realized by connecting and invoking OP-TEE SCMI service
interface PTA.

Optee transport support (CONFIG_ARM_SCMI_TRANSPORT_OPTEE) is default
enabled when optee driver (CONFIG_OPTEE) is enabled. Effective optee
transport is setup upon OP-TEE SCMI service discovery at optee
device initialization. For this SCMI UUID is registered to the optee
bus for probing. This is done from the link_supplier operator of the
SCMI optee transport.

The optee transport can use a statically defined shared memory in
which case SCMI device tree node defines it using an "arm,scmi-shmem"
compatible phandle through property shmem. Alternatively, optee transport
allocates the shared memory buffer from the optee driver when no shmem
property is defined.

The protocol used to exchange SCMI message over that shared memory is
negotiated between optee transport driver and the OP-TEE service through
capabilities exchange.

OP-TEE SCMI service is integrated in OP-TEE since its release tag 3.13.0.
The service interface is published in [1].

Link: [1] https://github.com/OP-TEE/optee_os/blob/3.13.0/lib/libutee/include/pta_scmi_client.h
Cc: Cristian Marussi <cristian.marussi@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
---
Changes since v6:
 - Fixed at last s/CFG_OPTEE/CONFIG_OPTEE/ in commit log.

Changes since v5:
 - scmi_optee_link_supplier() doesn't test scmi_optee_private->tee_ctx.
 - Free allocated shared memory when scmi_optee_chan_setup() fails.
 - Close session to TEE SCMI service when SCMI channel is freed.
 - Use SCMI_OPTEE_MAX_MSG_SIZE in SCMI transport descriptor.

Changes since v4:
 - Fix commit log that was not updated to v4 changes.
 - Operator scmi_optee_chan_setup() don't need the defer probe
   operation, it's already done from scmi_optee_link_supplier().

Changes since v3:
 - Fix use of configuration switches when CONFIG_OPTEE and
   CONFIG_ARM_SCMI_PROTOCOL are enabled/modules/disabled.
   Mimics scmi virtio integration.
 - Implement link_supplier operator for the scmi_optee transport
   to possibly defer probing when optee bus has not yet enumerated
   the SCMI OP-TEE service. The function ensures scmi_optee registers
   to optee bus enumeration when probe is deferred.
 - Add memory barriers to protect global optee service reference
   when it's updated at transport initialization and removal.
 - Replace enum pta_scmi_caps with macro definitions as enumerated
   types do not really match bit flags definitions. The capabilities
   data is now of type u32.
 - Use scmi_optee_ prefix for scmi transport operator handles
   and few other resources.
 - Fix typo: s/optee_smci_pta_cmd/optee_scmi_pta_cmd/
 - Remove useless DRIVER_NAME.
 - Minor reordering in struct optee_channel.
 - Removed some useless empty lines.

Changes since v2:
- Rebase on for-next/scmi, based on Linux v5.15-rc1.
- Implement support for dynamic and static shared memory.
- Factorize some functions and simplify transport exit sequence.
- Rename driver source file from optee_service.c to optee.c.

No change since v1
---
 drivers/firmware/arm_scmi/Kconfig  |  12 +
 drivers/firmware/arm_scmi/Makefile |   1 +
 drivers/firmware/arm_scmi/common.h |   3 +
 drivers/firmware/arm_scmi/driver.c |   3 +
 drivers/firmware/arm_scmi/optee.c  | 580 +++++++++++++++++++++++++++++
 5 files changed, 599 insertions(+)
 create mode 100644 drivers/firmware/arm_scmi/optee.c

diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig
index 3d7081e84853..30746350349c 100644
--- a/drivers/firmware/arm_scmi/Kconfig
+++ b/drivers/firmware/arm_scmi/Kconfig
@@ -77,6 +77,18 @@ config ARM_SCMI_TRANSPORT_VIRTIO
 	  If you want the ARM SCMI PROTOCOL stack to include support for a
 	  transport based on VirtIO, answer Y.
 
+config ARM_SCMI_TRANSPORT_OPTEE
+	bool "SCMI transport based on OP-TEE service"
+	depends on OPTEE=y || OPTEE=ARM_SCMI_PROTOCOL
+	select ARM_SCMI_HAVE_TRANSPORT
+	select ARM_SCMI_HAVE_SHMEM
+	default y
+	help
+	  This enables the OP-TEE service based transport for SCMI.
+
+	  If you want the ARM SCMI PROTOCOL stack to include support for a
+	  transport based on OP-TEE SCMI service, answer Y.
+
 endif #ARM_SCMI_PROTOCOL
 
 config ARM_SCMI_POWER_DOMAIN
diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
index 1dcf123d64ab..ef66ec8ca917 100644
--- a/drivers/firmware/arm_scmi/Makefile
+++ b/drivers/firmware/arm_scmi/Makefile
@@ -6,6 +6,7 @@ scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_MAILBOX) += mailbox.o
 scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_SMC) += smc.o
 scmi-transport-$(CONFIG_ARM_SCMI_HAVE_MSG) += msg.o
 scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_VIRTIO) += virtio.o
+scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_OPTEE) += optee.o
 scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o voltage.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 dea1bfbe1052..6438b5248c24 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -421,6 +421,9 @@ extern const struct scmi_desc scmi_smc_desc;
 #ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
 extern const struct scmi_desc scmi_virtio_desc;
 #endif
+#ifdef CONFIG_ARM_SCMI_TRANSPORT_OPTEE
+extern const struct scmi_desc scmi_optee_desc;
+#endif
 
 void scmi_rx_callback(struct scmi_chan_info *cinfo, u32 msg_hdr, void *priv);
 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 b406b3f78f46..e3f87e0c4936 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1999,6 +1999,9 @@ static const struct of_device_id scmi_of_match[] = {
 #endif
 #ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
 	{ .compatible = "arm,scmi-virtio", .data = &scmi_virtio_desc},
+#endif
+#ifdef CONFIG_ARM_SCMI_TRANSPORT_OPTEE
+	{ .compatible = "linaro,scmi-optee", .data = &scmi_optee_desc },
 #endif
 	{ /* Sentinel */ },
 };
diff --git a/drivers/firmware/arm_scmi/optee.c b/drivers/firmware/arm_scmi/optee.c
new file mode 100644
index 000000000000..8ad3135375e1
--- /dev/null
+++ b/drivers/firmware/arm_scmi/optee.c
@@ -0,0 +1,580 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019-2021 Linaro Ltd.
+ */
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/tee_drv.h>
+#include <linux/uuid.h>
+#include <uapi/linux/tee.h>
+
+#include "common.h"
+
+#define SCMI_OPTEE_MAX_MSG_SIZE		128
+
+enum scmi_optee_pta_cmd {
+	/*
+	 * PTA_SCMI_CMD_CAPABILITIES - Get channel capabilities
+	 *
+	 * [out]    value[0].a: Capability bit mask (enum pta_scmi_caps)
+	 * [out]    value[0].b: Extended capabilities or 0
+	 */
+	PTA_SCMI_CMD_CAPABILITIES = 0,
+
+	/*
+	 * PTA_SCMI_CMD_PROCESS_SMT_CHANNEL - Process SCMI message in SMT buffer
+	 *
+	 * [in]     value[0].a: Channel handle
+	 *
+	 * Shared memory used for SCMI message/response exhange is expected
+	 * already identified and bound to channel handle in both SCMI agent
+	 * and SCMI server (OP-TEE) parts.
+	 * The memory uses SMT header to carry SCMI meta-data (protocol ID and
+	 * protocol message ID).
+	 */
+	PTA_SCMI_CMD_PROCESS_SMT_CHANNEL = 1,
+
+	/*
+	 * PTA_SCMI_CMD_PROCESS_SMT_CHANNEL_MESSAGE - Process SMT/SCMI message
+	 *
+	 * [in]     value[0].a: Channel handle
+	 * [in/out] memref[1]: Message/response buffer (SMT and SCMI payload)
+	 *
+	 * Shared memory used for SCMI message/response is a SMT buffer
+	 * referenced by param[1]. It shall be 128 bytes large to fit response
+	 * payload whatever message playload size.
+	 * The memory uses SMT header to carry SCMI meta-data (protocol ID and
+	 * protocol message ID).
+	 */
+	PTA_SCMI_CMD_PROCESS_SMT_CHANNEL_MESSAGE = 2,
+
+	/*
+	 * PTA_SCMI_CMD_GET_CHANNEL - Get channel handle
+	 *
+	 * SCMI shm information are 0 if agent expects to use OP-TEE regular SHM
+	 *
+	 * [in]     value[0].a: Channel identifier
+	 * [out]    value[0].a: Returned channel handle
+	 * [in]     value[0].b: Requested capabilities mask (enum pta_scmi_caps)
+	 */
+	PTA_SCMI_CMD_GET_CHANNEL = 3,
+};
+
+/*
+ * OP-TEE SCMI service capabilities bit flags (32bit)
+ *
+ * PTA_SCMI_CAPS_SMT_HEADER
+ * When set, OP-TEE supports command using SMT header protocol (SCMI shmem) in
+ * shared memory buffers to carry SCMI protocol synchronisation information.
+ */
+#define PTA_SCMI_CAPS_NONE		0
+#define PTA_SCMI_CAPS_SMT_HEADER	BIT(0)
+
+/**
+ * struct scmi_optee_channel - Description of an OP-TEE SCMI channel
+ *
+ * @channel_id: OP-TEE channel ID used for this transport
+ * @tee_session: TEE session identifier
+ * @caps: OP-TEE SCMI channel capabilities
+ * @mu: Mutex protection on channel access
+ * @cinfo: SCMI channel information
+ * @shmem: Virtual base address of the shared memory
+ * @tee_shm: Reference to TEE shared memory or NULL if using static shmem
+ * @link: Reference in agent's channel list
+ */
+struct scmi_optee_channel {
+	u32 channel_id;
+	u32 tee_session;
+	u32 caps;
+	struct mutex mu;
+	struct scmi_chan_info *cinfo;
+	struct scmi_shared_mem __iomem *shmem;
+	struct tee_shm *tee_shm;
+	struct list_head link;
+};
+
+/**
+ * struct scmi_optee_agent - OP-TEE transport private data
+ *
+ * @dev: Device used for communication with TEE
+ * @tee_ctx: TEE context used for communication
+ * @caps: Supported channel capabilities
+ * @mu: Mutex for protection of @channel_list
+ * @channel_list: List of all created channels for the agent
+ */
+struct scmi_optee_agent {
+	struct device *dev;
+	struct tee_context *tee_ctx;
+	u32 caps;
+	struct mutex mu;
+	struct list_head channel_list;
+};
+
+/* There can be only 1 SCMI service in OP-TEE we connect to */
+static struct scmi_optee_agent *scmi_optee_private;
+
+/* Forward reference to scmi_optee transport initialization */
+static int scmi_optee_init(void);
+
+/* Open a session toward SCMI OP-TEE service with REE_KERNEL identity */
+static int open_session(struct scmi_optee_agent *agent, u32 *tee_session)
+{
+	struct device *dev = agent->dev;
+	struct tee_client_device *scmi_pta = to_tee_client_device(dev);
+	struct tee_ioctl_open_session_arg arg = { };
+	int ret;
+
+	memcpy(arg.uuid, scmi_pta->id.uuid.b, TEE_IOCTL_UUID_LEN);
+	arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
+
+	ret = tee_client_open_session(agent->tee_ctx, &arg, NULL);
+	if (ret < 0 || arg.ret) {
+		dev_err(dev, "Can't open tee session: %d / %#x\n", ret, arg.ret);
+		return -EOPNOTSUPP;
+	}
+
+	*tee_session = arg.session;
+
+	return 0;
+}
+
+static void close_session(struct scmi_optee_agent *agent, u32 tee_session)
+{
+	tee_client_close_session(agent->tee_ctx, tee_session);
+}
+
+static int get_capabilities(struct scmi_optee_agent *agent)
+{
+	struct tee_ioctl_invoke_arg arg = { };
+	struct tee_param param[1] = { };
+	u32 caps;
+	u32 tee_session;
+	int ret;
+
+	ret = open_session(agent, &tee_session);
+	if (ret)
+		return ret;
+
+	arg.func = PTA_SCMI_CMD_CAPABILITIES;
+	arg.session = tee_session;
+	arg.num_params = 1;
+
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
+
+	ret = tee_client_invoke_func(agent->tee_ctx, &arg, param);
+
+	close_session(agent, tee_session);
+
+	if (ret < 0 || arg.ret) {
+		dev_err(agent->dev, "Can't get capabilities: %d / %#x\n", ret, arg.ret);
+		return -EOPNOTSUPP;
+	}
+
+	caps = param[0].u.value.a;
+
+	if (!(caps & PTA_SCMI_CAPS_SMT_HEADER)) {
+		dev_err(agent->dev, "OP-TEE SCMI PTA doesn't support SMT\n");
+		return -EOPNOTSUPP;
+	}
+
+	agent->caps = caps;
+
+	return 0;
+}
+
+static int get_channel(struct scmi_optee_channel *channel)
+{
+	struct device *dev = scmi_optee_private->dev;
+	struct tee_ioctl_invoke_arg arg = { };
+	struct tee_param param[1] = { };
+	unsigned int caps = PTA_SCMI_CAPS_SMT_HEADER;
+	int ret;
+
+	arg.func = PTA_SCMI_CMD_GET_CHANNEL;
+	arg.session = channel->tee_session;
+	arg.num_params = 1;
+
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT;
+	param[0].u.value.a = channel->channel_id;
+	param[0].u.value.b = caps;
+
+	ret = tee_client_invoke_func(scmi_optee_private->tee_ctx, &arg, param);
+
+	if (ret || arg.ret) {
+		dev_err(dev, "Can't get channel with caps %#x: %d / %#x\n", caps, ret, arg.ret);
+		return -EOPNOTSUPP;
+	}
+
+	/* From now on use channel identifer provided by OP-TEE SCMI service */
+	channel->channel_id = param[0].u.value.a;
+	channel->caps = caps;
+
+	return 0;
+}
+
+static int invoke_process_smt_channel(struct scmi_optee_channel *channel)
+{
+	struct tee_ioctl_invoke_arg arg = { };
+	struct tee_param param[2] = { };
+	int ret;
+
+	arg.session = channel->tee_session;
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT;
+	param[0].u.value.a = channel->channel_id;
+
+	if (channel->tee_shm) {
+		param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT;
+		param[1].u.memref.shm = channel->tee_shm;
+		param[1].u.memref.size = SCMI_OPTEE_MAX_MSG_SIZE;
+		arg.num_params = 2;
+		arg.func = PTA_SCMI_CMD_PROCESS_SMT_CHANNEL_MESSAGE;
+	} else {
+		arg.num_params = 1;
+		arg.func = PTA_SCMI_CMD_PROCESS_SMT_CHANNEL;
+	}
+
+	ret = tee_client_invoke_func(scmi_optee_private->tee_ctx, &arg, param);
+	if (ret < 0 || arg.ret) {
+		dev_err(scmi_optee_private->dev, "Can't invoke channel %u: %d / %#x\n",
+			channel->channel_id, ret, arg.ret);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int scmi_optee_link_supplier(struct device *dev)
+{
+	if (!scmi_optee_private) {
+		if (scmi_optee_init())
+			dev_dbg(dev, "Optee bus not yet ready\n");
+
+		/* Wait for optee bus */
+		return -EPROBE_DEFER;
+	}
+
+	if (!device_link_add(dev, scmi_optee_private->dev, DL_FLAG_AUTOREMOVE_CONSUMER)) {
+		dev_err(dev, "Adding link to supplier optee device failed\n");
+		return -ECANCELED;
+	}
+
+	return 0;
+}
+
+static bool scmi_optee_chan_available(struct device *dev, int idx)
+{
+	u32 channel_id;
+
+	return !of_property_read_u32_index(dev->of_node, "linaro,optee-channel-id",
+					   idx, &channel_id);
+}
+
+static void scmi_optee_clear_channel(struct scmi_chan_info *cinfo)
+{
+	struct scmi_optee_channel *channel = cinfo->transport_info;
+
+	shmem_clear_channel(channel->shmem);
+}
+
+static int setup_dynamic_shmem(struct device *dev, struct scmi_optee_channel *channel)
+{
+	const size_t msg_size = SCMI_OPTEE_MAX_MSG_SIZE;
+
+	channel->tee_shm = tee_shm_alloc_kernel_buf(scmi_optee_private->tee_ctx, msg_size);
+	if (IS_ERR(channel->tee_shm)) {
+		dev_err(channel->cinfo->dev, "shmem allocation failed\n");
+		return -ENOMEM;
+	}
+
+	channel->shmem = (void *)tee_shm_get_va(channel->tee_shm, 0);
+	memset(channel->shmem, 0, msg_size);
+	shmem_clear_channel(channel->shmem);
+
+	return 0;
+}
+
+static int setup_static_shmem(struct device *dev, struct scmi_chan_info *cinfo,
+			      struct scmi_optee_channel *channel)
+{
+	struct device_node *np;
+	resource_size_t size;
+	struct resource res;
+	int ret;
+
+	np = of_parse_phandle(cinfo->dev->of_node, "shmem", 0);
+	if (!of_device_is_compatible(np, "arm,scmi-shmem")) {
+		ret = -ENXIO;
+		goto out;
+	}
+
+	ret = of_address_to_resource(np, 0, &res);
+	if (ret) {
+		dev_err(dev, "Failed to get SCMI Tx shared memory\n");
+		goto out;
+	}
+
+	size = resource_size(&res);
+
+	channel->shmem = devm_ioremap(dev, res.start, size);
+	if (!channel->shmem) {
+		dev_err(dev, "Failed to ioremap SCMI Tx shared memory\n");
+		ret = -EADDRNOTAVAIL;
+		goto out;
+	}
+
+	ret = 0;
+
+out:
+	of_node_put(np);
+
+	return ret;
+}
+
+static int setup_shmem(struct device *dev, struct scmi_chan_info *cinfo,
+		       struct scmi_optee_channel *channel)
+{
+	if (of_find_property(cinfo->dev->of_node, "shmem", NULL))
+		return setup_static_shmem(dev, cinfo, channel);
+	else
+		return setup_dynamic_shmem(dev, channel);
+}
+
+static int scmi_optee_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, bool tx)
+{
+	struct scmi_optee_channel *channel;
+	uint32_t channel_id;
+	int ret;
+
+	if (!tx)
+		return -ENODEV;
+
+	channel = devm_kzalloc(dev, sizeof(*channel), GFP_KERNEL);
+	if (!channel)
+		return -ENOMEM;
+
+	ret = of_property_read_u32_index(cinfo->dev->of_node, "linaro,optee-channel-id",
+					 0, &channel_id);
+	if (ret)
+		return ret;
+
+	cinfo->transport_info = channel;
+	channel->cinfo = cinfo;
+	channel->channel_id = channel_id;
+	mutex_init(&channel->mu);
+
+	ret = setup_shmem(dev, cinfo, channel);
+	if (ret)
+		return ret;
+
+	ret = open_session(scmi_optee_private, &channel->tee_session);
+	if (ret)
+		goto err_free_shm;
+
+	ret = get_channel(channel);
+	if (ret)
+		goto err_close_sess;
+
+	mutex_lock(&scmi_optee_private->mu);
+	list_add(&channel->link, &scmi_optee_private->channel_list);
+	mutex_unlock(&scmi_optee_private->mu);
+
+	return 0;
+
+err_close_sess:
+	close_session(scmi_optee_private, channel->tee_session);
+err_free_shm:
+	if (channel->tee_shm)
+		tee_shm_free(channel->tee_shm);
+
+	return ret;
+}
+
+static int scmi_optee_chan_free(int id, void *p, void *data)
+{
+	struct scmi_chan_info *cinfo = p;
+	struct scmi_optee_channel *channel = cinfo->transport_info;
+
+	mutex_lock(&scmi_optee_private->mu);
+	list_del(&channel->link);
+	mutex_unlock(&scmi_optee_private->mu);
+
+	close_session(scmi_optee_private, channel->tee_session);
+
+	if (channel->tee_shm) {
+		tee_shm_free(channel->tee_shm);
+		channel->tee_shm = NULL;
+	}
+
+	cinfo->transport_info = NULL;
+	channel->cinfo = NULL;
+
+	scmi_free_channel(cinfo, data, id);
+
+	return 0;
+}
+
+static struct scmi_shared_mem *get_channel_shm(struct scmi_optee_channel *chan,
+					       struct scmi_xfer *xfer)
+{
+	if (!chan)
+		return NULL;
+
+	return chan->shmem;
+}
+
+
+static int scmi_optee_send_message(struct scmi_chan_info *cinfo,
+				   struct scmi_xfer *xfer)
+{
+	struct scmi_optee_channel *channel = cinfo->transport_info;
+	struct scmi_shared_mem *shmem = get_channel_shm(channel, xfer);
+	int ret;
+
+	mutex_lock(&channel->mu);
+	shmem_tx_prepare(shmem, xfer);
+
+	ret = invoke_process_smt_channel(channel);
+
+	scmi_rx_callback(cinfo, shmem_read_header(shmem), NULL);
+	mutex_unlock(&channel->mu);
+
+	return ret;
+}
+
+static void scmi_optee_fetch_response(struct scmi_chan_info *cinfo,
+				      struct scmi_xfer *xfer)
+{
+	struct scmi_optee_channel *channel = cinfo->transport_info;
+	struct scmi_shared_mem *shmem = get_channel_shm(channel, xfer);
+
+	shmem_fetch_response(shmem, xfer);
+}
+
+static bool scmi_optee_poll_done(struct scmi_chan_info *cinfo,
+				 struct scmi_xfer *xfer)
+{
+	struct scmi_optee_channel *channel = cinfo->transport_info;
+	struct scmi_shared_mem *shmem = get_channel_shm(channel, xfer);
+
+	return shmem_poll_done(shmem, xfer);
+}
+
+static struct scmi_transport_ops scmi_optee_ops = {
+	.link_supplier = scmi_optee_link_supplier,
+	.chan_available = scmi_optee_chan_available,
+	.chan_setup = scmi_optee_chan_setup,
+	.chan_free = scmi_optee_chan_free,
+	.send_message = scmi_optee_send_message,
+	.fetch_response = scmi_optee_fetch_response,
+	.clear_channel = scmi_optee_clear_channel,
+	.poll_done = scmi_optee_poll_done,
+};
+
+static int scmi_optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
+{
+	return ver->impl_id == TEE_IMPL_ID_OPTEE;
+}
+
+static int scmi_optee_service_probe(struct device *dev)
+{
+	struct scmi_optee_agent *agent;
+	struct tee_context *tee_ctx;
+	int ret;
+
+	/* Only one SCMI OP-TEE device allowed */
+	if (scmi_optee_private) {
+		dev_err(dev, "An SCMI OP-TEE device was already initialized: only one allowed\n");
+		return -EBUSY;
+	}
+
+	tee_ctx = tee_client_open_context(NULL, scmi_optee_ctx_match, NULL, NULL);
+	if (IS_ERR(tee_ctx))
+		return -ENODEV;
+
+	agent = devm_kzalloc(dev, sizeof(*agent), GFP_KERNEL);
+	if (!agent) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	agent->dev = dev;
+	agent->tee_ctx = tee_ctx;
+	INIT_LIST_HEAD(&agent->channel_list);
+
+	ret = get_capabilities(agent);
+	if (ret)
+		goto err;
+
+	/* Ensure agent resources are all visible before scmi_optee_private is */
+	smp_mb();
+	scmi_optee_private = agent;
+
+	return 0;
+
+err:
+	tee_client_close_context(tee_ctx);
+
+	return ret;
+}
+
+static int scmi_optee_service_remove(struct device *dev)
+{
+	struct scmi_optee_agent *agent = scmi_optee_private;
+
+	if (!scmi_optee_private)
+		return -EINVAL;
+
+	if (!list_empty(&scmi_optee_private->channel_list))
+		return -EBUSY;
+
+	/* Ensure cleared reference is visible before resources are released */
+	smp_store_mb(scmi_optee_private, NULL);
+
+	tee_client_close_context(agent->tee_ctx);
+
+	return 0;
+}
+
+static const struct tee_client_device_id scmi_optee_service_id[] = {
+	{
+		UUID_INIT(0xa8cfe406, 0xd4f5, 0x4a2e,
+			  0x9f, 0x8d, 0xa2, 0x5d, 0xc7, 0x54, 0xc0, 0x99)
+	},
+	{ }
+};
+
+MODULE_DEVICE_TABLE(tee, scmi_optee_service_id);
+
+static struct tee_client_driver scmi_optee_driver = {
+	.id_table	= scmi_optee_service_id,
+	.driver		= {
+		.name = "scmi-optee",
+		.bus = &tee_bus_type,
+		.probe = scmi_optee_service_probe,
+		.remove = scmi_optee_service_remove,
+	},
+};
+
+static int scmi_optee_init(void)
+{
+	return driver_register(&scmi_optee_driver.driver);
+}
+
+static void scmi_optee_exit(void)
+{
+	driver_unregister(&scmi_optee_driver.driver);
+}
+
+const struct scmi_desc scmi_optee_desc = {
+	.transport_exit = scmi_optee_exit,
+	.ops = &scmi_optee_ops,
+	.max_rx_timeout_ms = 30,
+	.max_msg = 20,
+	.max_msg_size = SCMI_OPTEE_MAX_MSG_SIZE,
+};
-- 
2.17.1

Re: [PATCH v7 2/2] firmware: arm_scmi: Add optee transport

[Cristian Marussi]

On Thu, Oct 28, 2021 at 09:53:44AM +0200, Etienne Carriere wrote:
> Add a new transport channel to the SCMI firmware interface driver for
> SCMI message exchange based on optee transport channel. The optee
> transport is realized by connecting and invoking OP-TEE SCMI service
> interface PTA.
> 

Hi Etienne,

I was going to just add Reviewed-by...but...

> Optee transport support (CONFIG_ARM_SCMI_TRANSPORT_OPTEE) is default
> enabled when optee driver (CONFIG_OPTEE) is enabled. Effective optee
> transport is setup upon OP-TEE SCMI service discovery at optee
> device initialization. For this SCMI UUID is registered to the optee
> bus for probing. This is done from the link_supplier operator of the
> SCMI optee transport.
> 
> The optee transport can use a statically defined shared memory in
> which case SCMI device tree node defines it using an "arm,scmi-shmem"
> compatible phandle through property shmem. Alternatively, optee transport
> allocates the shared memory buffer from the optee driver when no shmem
> property is defined.
> 
> The protocol used to exchange SCMI message over that shared memory is
> negotiated between optee transport driver and the OP-TEE service through
> capabilities exchange.
> 
> OP-TEE SCMI service is integrated in OP-TEE since its release tag 3.13.0.
> The service interface is published in [1].
> 
> Link: [1] https://github.com/OP-TEE/optee_os/blob/3.13.0/lib/libutee/include/pta_scmi_client.h
> Cc: Cristian Marussi <cristian.marussi@arm.com>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>

I build tested again...and booted without using it really, just to try load/unload
of the core SCMI module (so building with ARM_SCMI_PROTOCOL=m) and unfortunately
I spotted this warning:

root@deb-buster-arm64:~# insmod ./scmi-module.ko
root@deb-buster-arm64:~# rmmod ./scmi-module.ko

[   99.860225] ------------[ cut here ]------------
[   99.865006] Unexpected driver unregister!
[   99.869116] WARNING: CPU: 0 PID: 339 at drivers/base/driver.c:194 driver_unregister+0x50/0x60
[   99.877684] Modules linked in: scmi_module(-) [last unloaded: scmi_hwmon]
[   99.884501] CPU: 0 PID: 339 Comm: rmmod Not tainted 5.15.0-rc1-00003-g46a1949d5e4f #8
[   99.892352] Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Jun 30 2020
[   99.903156] pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   99.910136] pc : driver_unregister+0x50/0x60
[   99.914419] lr : driver_unregister+0x50/0x60
[   99.918701] sp : ffff80001259bd50
[   99.922018] x29: ffff80001259bd50 x28: ffff0008010a5280 x27: 0000000000000000
[   99.929182] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
[   99.936344] x23: 0000000000000000 x22: ffff8000121446d8 x21: ffff800011e19948
[   99.943506] x20: ffff800011ea7548 x19: ffff80000900b340 x18: 0000000000000010
[   99.950669] x17: 31333d4d554e5145 x16: 53007375623d4d45 x15: 000000000000017c
[   99.957831] x14: ffff80001259ba60 x13: 00000000ffffffea x12: ffff800011ea2e70
[   99.964994] x11: 0000000000000003 x10: ffff800011e8ae30 x9 : ffff800011e8ae88
[   99.972156] x8 : 0000000000017fe8 x7 : c0000000ffffefff x6 : ffff00097ef4e988
[   99.979318] x5 : ffff00097ef4e988 x4 : 0000000000000000 x3 : ffff00097ef51910
[   99.986480] x2 : ffff00097ef51910 x1 : c33162034fce8d00 x0 : 0000000000000000
[   99.993643] Call trace:
[   99.996092]  driver_unregister+0x50/0x60
[  100.000028]  scmi_optee_exit+0x1c/0x28 [scmi_module]
[  100.005040]  scmi_driver_exit+0x58/0x7c [scmi_module]
[  100.010131]  __arm64_sys_delete_module+0x19c/0x228
[  100.014938]  invoke_syscall+0x44/0x108
[  100.018700]  el0_svc_common.constprop.3+0x94/0xf8
[  100.023418]  do_el0_svc+0x24/0x88
[  100.026743]  el0_svc+0x20/0x50
[  100.029807]  el0t_64_sync_handler+0x90/0xb8
[  100.034001]  el0t_64_sync+0x180/0x184
[  100.037674] ---[ end trace 4c09a5e866689fa7 ]---

I suppose it could be that on my system I have not defined an OPTEE DT node, so
the transport is NEVER initialized (and driver_register) since you are doing it
in .link_supplier not in .transport_init, BUT then it is indeed always .exited
by the usual .transport_exit.

I would recommend adding a check on your exit to avoid this (probably using
scmi_optee_private to avoid unregistering if never registered ?).

Sorry, I think I thought about telling you about this check on .exit in previous
version but I did not eventaully.

Additionally, I have a slight concern if default-enabling it or not; as an
example virtio is default-N just because it felt like a more esoteric
transport not generally needed...but this will probably change indeed with all the
work you guys are doing on virtualizing the stack, so no strong opinion here ...

...and I'll happily let Sudeep decide on this :D.

Thanks,
Cristian

Re: [PATCH v7 2/2] firmware: arm_scmi: Add optee transport

[Etienne Carriere]

Hello Cristian,

On Thu, 28 Oct 2021 at 11:26, Cristian Marussi <cristian.marussi@arm.com> wrote:
>
> On Thu, Oct 28, 2021 at 09:53:44AM +0200, Etienne Carriere wrote:
> > Add a new transport channel to the SCMI firmware interface driver for
> > SCMI message exchange based on optee transport channel. The optee
> > transport is realized by connecting and invoking OP-TEE SCMI service
> > interface PTA.
> >
>
> Hi Etienne,
>
> I was going to just add Reviewed-by...but...
>
> > Optee transport support (CONFIG_ARM_SCMI_TRANSPORT_OPTEE) is default
> > enabled when optee driver (CONFIG_OPTEE) is enabled. Effective optee
> > transport is setup upon OP-TEE SCMI service discovery at optee
> > device initialization. For this SCMI UUID is registered to the optee
> > bus for probing. This is done from the link_supplier operator of the
> > SCMI optee transport.
> >
> > The optee transport can use a statically defined shared memory in
> > which case SCMI device tree node defines it using an "arm,scmi-shmem"
> > compatible phandle through property shmem. Alternatively, optee transport
> > allocates the shared memory buffer from the optee driver when no shmem
> > property is defined.
> >
> > The protocol used to exchange SCMI message over that shared memory is
> > negotiated between optee transport driver and the OP-TEE service through
> > capabilities exchange.
> >
> > OP-TEE SCMI service is integrated in OP-TEE since its release tag 3.13.0.
> > The service interface is published in [1].
> >
> > Link: [1] https://github.com/OP-TEE/optee_os/blob/3.13.0/lib/libutee/include/pta_scmi_client.h
> > Cc: Cristian Marussi <cristian.marussi@arm.com>
> > Cc: Sudeep Holla <sudeep.holla@arm.com>
> > Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
>
> I build tested again...and booted without using it really, just to try load/unload
> of the core SCMI module (so building with ARM_SCMI_PROTOCOL=m) and unfortunately
> I spotted this warning:
>
> root@deb-buster-arm64:~# insmod ./scmi-module.ko
> root@deb-buster-arm64:~# rmmod ./scmi-module.ko
>
> [   99.860225] ------------[ cut here ]------------
> [   99.865006] Unexpected driver unregister!
> [   99.869116] WARNING: CPU: 0 PID: 339 at drivers/base/driver.c:194 driver_unregister+0x50/0x60
> [   99.877684] Modules linked in: scmi_module(-) [last unloaded: scmi_hwmon]
> [   99.884501] CPU: 0 PID: 339 Comm: rmmod Not tainted 5.15.0-rc1-00003-g46a1949d5e4f #8
> [   99.892352] Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Jun 30 2020
> [   99.903156] pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [   99.910136] pc : driver_unregister+0x50/0x60
> [   99.914419] lr : driver_unregister+0x50/0x60
> [   99.918701] sp : ffff80001259bd50
> [   99.922018] x29: ffff80001259bd50 x28: ffff0008010a5280 x27: 0000000000000000
> [   99.929182] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
> [   99.936344] x23: 0000000000000000 x22: ffff8000121446d8 x21: ffff800011e19948
> [   99.943506] x20: ffff800011ea7548 x19: ffff80000900b340 x18: 0000000000000010
> [   99.950669] x17: 31333d4d554e5145 x16: 53007375623d4d45 x15: 000000000000017c
> [   99.957831] x14: ffff80001259ba60 x13: 00000000ffffffea x12: ffff800011ea2e70
> [   99.964994] x11: 0000000000000003 x10: ffff800011e8ae30 x9 : ffff800011e8ae88
> [   99.972156] x8 : 0000000000017fe8 x7 : c0000000ffffefff x6 : ffff00097ef4e988
> [   99.979318] x5 : ffff00097ef4e988 x4 : 0000000000000000 x3 : ffff00097ef51910
> [   99.986480] x2 : ffff00097ef51910 x1 : c33162034fce8d00 x0 : 0000000000000000
> [   99.993643] Call trace:
> [   99.996092]  driver_unregister+0x50/0x60
> [  100.000028]  scmi_optee_exit+0x1c/0x28 [scmi_module]
> [  100.005040]  scmi_driver_exit+0x58/0x7c [scmi_module]
> [  100.010131]  __arm64_sys_delete_module+0x19c/0x228
> [  100.014938]  invoke_syscall+0x44/0x108
> [  100.018700]  el0_svc_common.constprop.3+0x94/0xf8
> [  100.023418]  do_el0_svc+0x24/0x88
> [  100.026743]  el0_svc+0x20/0x50
> [  100.029807]  el0t_64_sync_handler+0x90/0xb8
> [  100.034001]  el0t_64_sync+0x180/0x184
> [  100.037674] ---[ end trace 4c09a5e866689fa7 ]---
>
> I suppose it could be that on my system I have not defined an OPTEE DT node, so
> the transport is NEVER initialized (and driver_register) since you are doing it
> in .link_supplier not in .transport_init, BUT then it is indeed always .exited
> by the usual .transport_exit.
>
> I would recommend adding a check on your exit to avoid this (probably using
> scmi_optee_private to avoid unregistering if never registered ?).

Fully make sense, yes. If transport was not initialized (from scmi
link_supplier), it cannot be unregistered (from scmi transport_exit).
I'll follow your suggestion.

>
> Sorry, I think I thought about telling you about this check on .exit in previous
> version but I did not eventaully.

Don't be sorry and many thanks again for the reviews, feedback and guidelines.

>
> Additionally, I have a slight concern if default-enabling it or not; as an
> example virtio is default-N just because it felt like a more esoteric
> transport not generally needed...but this will probably change indeed with all the
> work you guys are doing on virtualizing the stack, so no strong opinion here ...
>
> ...and I'll happily let Sudeep decide on this :D.

Sure. From my view, once both CONFIG_ARM_SCMI_PROTOCOL and
CONFIG_OPTEE are enabled, we can enable SCMI optee transport since it
will be initialized only upon discovery of the OP-TEE firmware SCMI
service (using the tee bus).

Cheers,
Etienne

>
> Thanks,
> Cristian