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From:   Etienne Carriere <etienne.carriere@linaro.org>
To:     linux-kernel@vger.kernel.org
Cc:     linux-arm-kernel@lists.infradead.org,
        Sudeep Holla <sudeep.holla@arm.com>,
        Cristian Marussi <cristian.marussi@arm.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Etienne Carriere <etienne.carriere@linaro.org>
Subject: [PATCH v3] firmware: arm_scmi: support optee shared memory in optee transport
Date:   Mon, 25 Apr 2022 10:51:27 +0200
Message-Id: <20220425085127.2009-1-etienne.carriere@linaro.org>
Precedence: bulk

Adds support for tee shared memory in optee scmi transport. When using
tee shared memory, scmi optee transport manages SCMI messages using
msg protocol (from msg.c) in shared memory, whereas smt (from shmem.c)
protocol is used with static IOMEM shared buffers.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
---
Changes since v2:
- Select configuration switch ARM_SCMI_HAVE_MSG when
  ARM_SCMI_TRANSPORT_OPTEE is enabled.
- Don't consider tee_shm in invoke_process_smt_channel() since
  this function now assumes TEE shared memory is not used for SMT
  based channel.

Changes since v1:
- Remove call to scmi_rx_callback() in scmi_optee_send_message().
---
 drivers/firmware/arm_scmi/Kconfig |   1 +
 drivers/firmware/arm_scmi/optee.c | 144 ++++++++++++++++++++++--------
 2 files changed, 109 insertions(+), 36 deletions(-)

diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig
index 7794bd41eaa0..1e7b7fec97d9 100644
--- a/drivers/firmware/arm_scmi/Kconfig
+++ b/drivers/firmware/arm_scmi/Kconfig
@@ -59,6 +59,7 @@ config ARM_SCMI_TRANSPORT_OPTEE
 	depends on OPTEE=y || OPTEE=ARM_SCMI_PROTOCOL
 	select ARM_SCMI_HAVE_TRANSPORT
 	select ARM_SCMI_HAVE_SHMEM
+	select ARM_SCMI_HAVE_MSG
 	default y
 	help
 	  This enables the OP-TEE service based transport for SCMI.
diff --git a/drivers/firmware/arm_scmi/optee.c b/drivers/firmware/arm_scmi/optee.c
index 8302a2b4aeeb..b503c22cfd32 100644
--- a/drivers/firmware/arm_scmi/optee.c
+++ b/drivers/firmware/arm_scmi/optee.c
@@ -64,6 +64,22 @@ enum scmi_optee_pta_cmd {
 	 * [in]     value[0].b: Requested capabilities mask (enum pta_scmi_caps)
 	 */
 	PTA_SCMI_CMD_GET_CHANNEL = 3,
+
+	/*
+	 * PTA_SCMI_CMD_PROCESS_MSG_CHANNEL - Process SCMI message in a MSG
+	 * buffer pointed by memref parameters
+	 *
+	 * [in]     value[0].a: Channel handle
+	 * [in]     memref[1]: Message buffer (MSG and SCMI payload)
+	 * [out]    memref[2]: Response buffer (MSG and SCMI payload)
+	 *
+	 * Shared memories used for SCMI message/response are MSG buffers
+	 * referenced by param[1] and param[2]. MSG transport protocol
+	 * uses a 32bit header to carry SCMI meta-data (protocol ID and
+	 * protocol message ID) followed by the effective SCMI message
+	 * payload.
+	 */
+	PTA_SCMI_CMD_PROCESS_MSG_CHANNEL = 4,
 };
 
 /*
@@ -72,9 +88,17 @@ enum scmi_optee_pta_cmd {
  * 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.
+ *
+ * PTA_SCMI_CAPS_MSG_HEADER
+ * When set, OP-TEE supports command using MSG header protocol in an OP-TEE
+ * shared memory to carry SCMI protocol synchronisation information and SCMI
+ * message payload.
  */
 #define PTA_SCMI_CAPS_NONE		0
 #define PTA_SCMI_CAPS_SMT_HEADER	BIT(0)
+#define PTA_SCMI_CAPS_MSG_HEADER	BIT(1)
+#define PTA_SCMI_CAPS_MASK		(PTA_SCMI_CAPS_SMT_HEADER | \
+					 PTA_SCMI_CAPS_MSG_HEADER)
 
 /**
  * struct scmi_optee_channel - Description of an OP-TEE SCMI channel
@@ -85,7 +109,8 @@ enum scmi_optee_pta_cmd {
  * @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
+ * @req: Shared memory protocol handle for SCMI request and synchronous response
+ * @tee_shm: TEE shared memory handle @req or NULL if using IOMEM shmem
  * @link: Reference in agent's channel list
  */
 struct scmi_optee_channel {
@@ -94,7 +119,10 @@ struct scmi_optee_channel {
 	u32 caps;
 	struct mutex mu;
 	struct scmi_chan_info *cinfo;
-	struct scmi_shared_mem __iomem *shmem;
+	union {
+		struct scmi_shared_mem __iomem *shmem;
+		struct scmi_msg_payld *msg;
+	} req;
 	struct tee_shm *tee_shm;
 	struct list_head link;
 };
@@ -178,8 +206,8 @@ static int get_capabilities(struct scmi_optee_agent *agent)
 
 	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");
+	if (!(caps & (PTA_SCMI_CAPS_SMT_HEADER | PTA_SCMI_CAPS_MSG_HEADER))) {
+		dev_err(agent->dev, "OP-TEE SCMI PTA doesn't support SMT and MSG\n");
 		return -EOPNOTSUPP;
 	}
 
@@ -193,9 +221,14 @@ 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;
+	unsigned int caps = 0;
 	int ret;
 
+	if (channel->tee_shm)
+		caps = PTA_SCMI_CAPS_MSG_HEADER;
+	else
+		caps = PTA_SCMI_CAPS_SMT_HEADER;
+
 	arg.func = PTA_SCMI_CMD_GET_CHANNEL;
 	arg.session = channel->tee_session;
 	arg.num_params = 1;
@@ -220,25 +253,48 @@ static int get_channel(struct scmi_optee_channel *channel)
 
 static int invoke_process_smt_channel(struct scmi_optee_channel *channel)
 {
-	struct tee_ioctl_invoke_arg arg = { };
-	struct tee_param param[2] = { };
+	struct tee_ioctl_invoke_arg arg = {
+		.func = PTA_SCMI_CMD_PROCESS_SMT_CHANNEL,
+		.session = channel->tee_session,
+		.num_params = 1,
+	};
+	struct tee_param param[1] = { };
 	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 invoke_process_msg_channel(struct scmi_optee_channel *channel, size_t msg_size)
+{
+	struct tee_ioctl_invoke_arg arg = {
+		.func = PTA_SCMI_CMD_PROCESS_MSG_CHANNEL,
+		.session = channel->tee_session,
+		.num_params = 3,
+	};
+	struct tee_param param[3] = { };
+	int ret;
+
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT;
+	param[0].u.value.a = channel->channel_id;
+
+	param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
+	param[1].u.memref.shm = channel->tee_shm;
+	param[1].u.memref.size = msg_size;
+
+	param[2].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
+	param[2].u.memref.shm = channel->tee_shm;
+	param[2].u.memref.size = SCMI_OPTEE_MAX_MSG_SIZE;
+
 	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",
@@ -279,7 +335,26 @@ static void scmi_optee_clear_channel(struct scmi_chan_info *cinfo)
 {
 	struct scmi_optee_channel *channel = cinfo->transport_info;
 
-	shmem_clear_channel(channel->shmem);
+	if (!channel->tee_shm)
+		shmem_clear_channel(channel->req.shmem);
+}
+
+static int setup_dynamic_shmem(struct device *dev, struct scmi_optee_channel *channel)
+{
+	const size_t msg_size = SCMI_OPTEE_MAX_MSG_SIZE;
+	void *shbuf;
+
+	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;
+	}
+
+	shbuf = tee_shm_get_va(channel->tee_shm, 0);
+	memset(shbuf, 0, msg_size);
+	channel->req.msg = shbuf;
+
+	return 0;
 }
 
 static int setup_static_shmem(struct device *dev, struct scmi_chan_info *cinfo,
@@ -304,8 +379,8 @@ static int setup_static_shmem(struct device *dev, struct scmi_chan_info *cinfo,
 
 	size = resource_size(&res);
 
-	channel->shmem = devm_ioremap(dev, res.start, size);
-	if (!channel->shmem) {
+	channel->req.shmem = devm_ioremap(dev, res.start, size);
+	if (!channel->req.shmem) {
 		dev_err(dev, "Failed to ioremap SCMI Tx shared memory\n");
 		ret = -EADDRNOTAVAIL;
 		goto out;
@@ -325,7 +400,7 @@ static int setup_shmem(struct device *dev, struct scmi_chan_info *cinfo,
 	if (of_find_property(cinfo->dev->of_node, "shmem", NULL))
 		return setup_static_shmem(dev, cinfo, channel);
 	else
-		return -ENOMEM;
+		return setup_dynamic_shmem(dev, channel);
 }
 
 static int scmi_optee_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, bool tx)
@@ -405,27 +480,22 @@ static int scmi_optee_chan_free(int id, void *p, void *data)
 	return 0;
 }
 
-static struct scmi_shared_mem __iomem *
-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 __iomem *shmem = get_channel_shm(channel, xfer);
 	int ret;
 
 	mutex_lock(&channel->mu);
-	shmem_tx_prepare(shmem, xfer);
 
-	ret = invoke_process_smt_channel(channel);
+	if (channel->tee_shm) {
+		msg_tx_prepare(channel->req.msg, xfer);
+		ret = invoke_process_msg_channel(channel, msg_command_size(xfer));
+	} else {
+		shmem_tx_prepare(channel->req.shmem, xfer);
+		ret = invoke_process_smt_channel(channel);
+	}
+
 	if (ret)
 		mutex_unlock(&channel->mu);
 
@@ -436,9 +506,11 @@ 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 __iomem *shmem = get_channel_shm(channel, xfer);
 
-	shmem_fetch_response(shmem, xfer);
+	if (channel->tee_shm)
+		msg_fetch_response(channel->req.msg, SCMI_OPTEE_MAX_MSG_SIZE, xfer);
+	else
+		shmem_fetch_response(channel->req.shmem, xfer);
 }
 
 static void scmi_optee_mark_txdone(struct scmi_chan_info *cinfo, int ret,
-- 
2.17.1