firmware: scmi: support Arm SMCCC transport
This change implements a SMCCC transport for SCMI exchanges. This
implementation follows the Linux kernel as references implementation
for SCMI message processing, using the SMT format for communication
channel meta-data.
Use of SMCCC transport in SCMI FDT bindings are defined in the Linux
kernel DT bindings since v5.8. SMCCC with SMT is implemented in OP-TEE
from tag 3.9.0 [2].
Links: [2] https://github.com/OP-TEE/optee_os/commit/a58c4d706d23
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/firmware/scmi/Kconfig b/drivers/firmware/scmi/Kconfig
index c501bf4..c3a109b 100644
--- a/drivers/firmware/scmi/Kconfig
+++ b/drivers/firmware/scmi/Kconfig
@@ -2,7 +2,7 @@
bool "Enable SCMI support"
select FIRMWARE
select OF_TRANSLATE
- depends on SANDBOX || DM_MAILBOX
+ depends on SANDBOX || DM_MAILBOX || ARM_SMCCC
help
System Control and Management Interface (SCMI) is a communication
protocol that defines standard interfaces for power, performance
@@ -15,5 +15,5 @@
Communications between agent (client) and the SCMI server are
based on message exchange. Messages can be exchange over tranport
- channels as a mailbox device with some piece of identified shared
- memory.
+ channels as a mailbox device or an Arm SMCCC service with some
+ piece of identified shared memory.
diff --git a/drivers/firmware/scmi/Makefile b/drivers/firmware/scmi/Makefile
index d22f53e..2f782bb 100644
--- a/drivers/firmware/scmi/Makefile
+++ b/drivers/firmware/scmi/Makefile
@@ -1,4 +1,5 @@
obj-y += scmi_agent-uclass.o
obj-y += smt.o
+obj-$(CONFIG_ARM_SMCCC) += smccc_agent.o
obj-$(CONFIG_DM_MAILBOX) += mailbox_agent.o
obj-$(CONFIG_SANDBOX) += sandbox-scmi_agent.o
diff --git a/drivers/firmware/scmi/smccc_agent.c b/drivers/firmware/scmi/smccc_agent.c
new file mode 100644
index 0000000..85dbf91
--- /dev/null
+++ b/drivers/firmware/scmi/smccc_agent.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 Linaro Limited.
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <scmi_agent.h>
+#include <scmi_agent-uclass.h>
+#include <dm/devres.h>
+#include <dm/device-internal.h>
+#include <linux/arm-smccc.h>
+#include <linux/compat.h>
+
+#include "smt.h"
+
+#define SMCCC_RET_NOT_SUPPORTED ((unsigned long)-1)
+
+/**
+ * struct scmi_smccc_channel - Description of an SCMI SMCCC transport
+ * @func_id: SMCCC function ID used by the SCMI transport
+ * @smt: Shared memory buffer
+ */
+struct scmi_smccc_channel {
+ ulong func_id;
+ struct scmi_smt smt;
+};
+
+static int scmi_smccc_process_msg(struct udevice *dev, struct scmi_msg *msg)
+{
+ struct scmi_smccc_channel *chan = dev_get_priv(dev);
+ struct arm_smccc_res res;
+ int ret;
+
+ ret = scmi_write_msg_to_smt(dev, &chan->smt, msg);
+ if (ret)
+ return ret;
+
+ arm_smccc_smc(chan->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
+ if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
+ ret = -ENXIO;
+ else
+ ret = scmi_read_resp_from_smt(dev, &chan->smt, msg);
+
+ scmi_clear_smt_channel(&chan->smt);
+
+ return ret;
+}
+
+static int scmi_smccc_probe(struct udevice *dev)
+{
+ struct scmi_smccc_channel *chan = dev_get_priv(dev);
+ u32 func_id;
+ int ret;
+
+ if (dev_read_u32(dev, "arm,smc-id", &func_id)) {
+ dev_err(dev, "Missing property func-id\n");
+ return -EINVAL;
+ }
+
+ chan->func_id = func_id;
+
+ ret = scmi_dt_get_smt_buffer(dev, &chan->smt);
+ if (ret) {
+ dev_err(dev, "Failed to get smt resources: %d\n", ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+static const struct udevice_id scmi_smccc_ids[] = {
+ { .compatible = "arm,scmi-smc" },
+ { }
+};
+
+static const struct scmi_agent_ops scmi_smccc_ops = {
+ .process_msg = scmi_smccc_process_msg,
+};
+
+U_BOOT_DRIVER(scmi_smccc) = {
+ .name = "scmi-over-smccc",
+ .id = UCLASS_SCMI_AGENT,
+ .of_match = scmi_smccc_ids,
+ .priv_auto_alloc_size = sizeof(struct scmi_smccc_channel),
+ .probe = scmi_smccc_probe,
+ .ops = &scmi_smccc_ops,
+};