firmware: arm_ffa: Add support for SMCCC as transport to FFA driver

There are requests to keep the transport separate in order to allow
other possible transports like virtio. So let us keep the SMCCC transport
specific routines abstracted.

It is kept simple for now. Once we add another transport, we can develop
better abstraction.

Link: https://lore.kernel.org/r/20210521151033.181846-4-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

4 files changed, 50 insertions, 1 deletions

diff --git a/drivers/firmware/arm_ffa/Kconfig b/drivers/firmware/arm_ffa/Kconfig
index 261a3660650a..5e3ae5cf82e8 100644
--- a/drivers/firmware/arm_ffa/Kconfig
+++ b/drivers/firmware/arm_ffa/Kconfig
@@ -14,3 +14,8 @@ config ARM_FFA_TRANSPORT
 
 	  This driver provides interface for all the client drivers making
 	  use of the features offered by ARM FF-A.
+
+config ARM_FFA_SMCCC
+	bool
+	default ARM_FFA_TRANSPORT
+	depends on ARM64 && HAVE_ARM_SMCCC_DISCOVERY
diff --git a/drivers/firmware/arm_ffa/Makefile b/drivers/firmware/arm_ffa/Makefile
index 82d0d35c5324..9d9f37523200 100644
--- a/drivers/firmware/arm_ffa/Makefile
+++ b/drivers/firmware/arm_ffa/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 ffa-bus-y = bus.o
 ffa-driver-y = driver.o
-ffa-module-objs := $(ffa-bus-y) $(ffa-driver-y)
+ffa-transport-$(CONFIG_ARM_FFA_SMCCC) += smccc.o
+ffa-module-objs := $(ffa-bus-y) $(ffa-driver-y) $(ffa-transport-y)
 obj-$(CONFIG_ARM_FFA_TRANSPORT) = ffa-module.o
diff --git a/drivers/firmware/arm_ffa/common.h b/drivers/firmware/arm_ffa/common.h
index 2d3a32f67d5d..f24754a59f47 100644
--- a/drivers/firmware/arm_ffa/common.h
+++ b/drivers/firmware/arm_ffa/common.h
@@ -16,9 +16,13 @@ typedef void (ffa_fn)(ffa_value_t, ffa_value_t *);
 int arm_ffa_bus_init(void);
 void arm_ffa_bus_exit(void);
 
+#ifdef CONFIG_ARM_FFA_SMCCC
+int __init ffa_transport_init(ffa_fn **invoke_ffa_fn);
+#else
 static inline int __init ffa_transport_init(ffa_fn **invoke_ffa_fn)
 {
 	return -EOPNOTSUPP;
 }
+#endif
 
 #endif /* _FFA_COMMON_H */
diff --git a/drivers/firmware/arm_ffa/smccc.c b/drivers/firmware/arm_ffa/smccc.c
new file mode 100644
index 000000000000..4d85bfff0a4e
--- /dev/null
+++ b/drivers/firmware/arm_ffa/smccc.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 ARM Ltd.
+ */
+
+#include <linux/printk.h>
+
+#include "common.h"
+
+static void __arm_ffa_fn_smc(ffa_value_t args, ffa_value_t *res)
+{
+	arm_smccc_1_2_smc(&args, res);
+}
+
+static void __arm_ffa_fn_hvc(ffa_value_t args, ffa_value_t *res)
+{
+	arm_smccc_1_2_hvc(&args, res);
+}
+
+int __init ffa_transport_init(ffa_fn **invoke_ffa_fn)
+{
+	enum arm_smccc_conduit conduit;
+
+	if (arm_smccc_get_version() < ARM_SMCCC_VERSION_1_2)
+		return -EOPNOTSUPP;
+
+	conduit = arm_smccc_1_1_get_conduit();
+	if (conduit == SMCCC_CONDUIT_NONE) {
+		pr_err("%s: invalid SMCCC conduit\n", __func__);
+		return -EOPNOTSUPP;
+	}
+
+	if (conduit == SMCCC_CONDUIT_SMC)
+		*invoke_ffa_fn = __arm_ffa_fn_smc;
+	else
+		*invoke_ffa_fn = __arm_ffa_fn_hvc;
+
+	return 0;
+}