firmware: arm_scmi: Make SMC transport a standalone driver

Make SCMI SMC transport a standalone driver that can be optionally
loaded as a module.

CC: Peng Fan <peng.fan@nxp.com>
CC: Nikunj Kela <quic_nkela@quicinc.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Message-Id: <20240812173340.3912830-7-cristian.marussi@arm.com>
[sudeep.holla: moved Clang Thumb2 build fix to the new makefile]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/Kconfig

@@ -84,32 +84,6 @@ config ARM_SCMI_TRANSPORT_OPTEE
 	  If you want the ARM SCMI PROTOCOL stack to include support for a
 	  transport based on OP-TEE SCMI service, answer Y.
 
-config ARM_SCMI_TRANSPORT_SMC
-	bool "SCMI transport based on SMC"
-	depends on HAVE_ARM_SMCCC_DISCOVERY
-	select ARM_SCMI_HAVE_TRANSPORT
-	select ARM_SCMI_HAVE_SHMEM
-	default y
-	help
-	  Enable SMC based transport for SCMI.
-
-	  If you want the ARM SCMI PROTOCOL stack to include support for a
-	  transport based on SMC, answer Y.
-
-config ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE
-	bool "Enable atomic mode support for SCMI SMC transport"
-	depends on ARM_SCMI_TRANSPORT_SMC
-	help
-	  Enable support of atomic operation for SCMI SMC based transport.
-
-	  If you want the SCMI SMC based transport to operate in atomic
-	  mode, avoiding any kind of sleeping behaviour for selected
-	  transactions on the TX path, answer Y.
-	  Enabling atomic mode operations allows any SCMI driver using this
-	  transport to optionally ask for atomic SCMI transactions and operate
-	  in atomic context too, at the price of using a number of busy-waiting
-	  primitives all over instead. If unsure say N.
-
 config ARM_SCMI_TRANSPORT_VIRTIO
 	bool "SCMI transport based on VirtIO"
 	depends on VIRTIO=y || VIRTIO=ARM_SCMI_PROTOCOL

drivers/firmware/arm_scmi/Makefile

@@ -5,7 +5,6 @@ scmi-core-objs := $(scmi-bus-y)
 scmi-driver-y = driver.o notify.o
 scmi-driver-$(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT) += raw_mode.o
 scmi-transport-$(CONFIG_ARM_SCMI_HAVE_SHMEM) = shmem.o
-scmi-transport-$(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-$(CONFIG_ARM_SCMI_TRANSPORT_OPTEE) += optee.o
@@ -19,10 +18,3 @@ obj-$(CONFIG_ARM_SCMI_PROTOCOL) += scmi-core.o
 obj-$(CONFIG_ARM_SCMI_PROTOCOL) += scmi-module.o
 
 obj-$(CONFIG_ARM_SCMI_POWER_CONTROL) += scmi_power_control.o
-
-ifeq ($(CONFIG_THUMB2_KERNEL)$(CONFIG_CC_IS_CLANG),yy)
-# The use of R7 in the SMCCC conflicts with the compiler's use of R7 as a frame
-# pointer in Thumb2 mode, which is forcibly enabled by Clang when profiling
-# hooks are inserted via the -pg switch.
-CFLAGS_REMOVE_smc.o += $(CC_FLAGS_FTRACE)
-endif

drivers/firmware/arm_scmi/common.h

@@ -286,9 +286,6 @@ int scmi_xfer_raw_inflight_register(const struct scmi_handle *handle,
 int scmi_xfer_raw_wait_for_message_response(struct scmi_chan_info *cinfo,
 					    struct scmi_xfer *xfer,
 					    unsigned int timeout_ms);
-#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC
-extern const struct scmi_desc scmi_smc_desc;
-#endif
 #ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
 extern const struct scmi_desc scmi_virtio_desc;
 #endif

drivers/firmware/arm_scmi/driver.c

@@ -3321,11 +3321,6 @@ static const struct of_device_id scmi_of_match[] = {
 #ifdef CONFIG_ARM_SCMI_TRANSPORT_OPTEE
 	{ .compatible = "linaro,scmi-optee", .data = &scmi_optee_desc },
 #endif
-#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC
-	{ .compatible = "arm,scmi-smc", .data = &scmi_smc_desc},
-	{ .compatible = "arm,scmi-smc-param", .data = &scmi_smc_desc},
-	{ .compatible = "qcom,scmi-smc", .data = &scmi_smc_desc},
-#endif
 #ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
 	{ .compatible = "arm,scmi-virtio", .data = &scmi_virtio_desc},
 #endif

drivers/firmware/arm_scmi/transports/Kconfig

@@ -34,4 +34,32 @@ config ARM_SCMI_TRANSPORT_MAILBOX
 	  This driver can also be built as a module. If so, the module
 	  will be called scmi_transport_mailbox.
 
+config ARM_SCMI_TRANSPORT_SMC
+	tristate "SCMI transport based on SMC"
+	depends on HAVE_ARM_SMCCC_DISCOVERY
+	select ARM_SCMI_HAVE_TRANSPORT
+	select ARM_SCMI_HAVE_SHMEM
+	default y
+	help
+	  Enable SMC based transport for SCMI.
+
+	  If you want the ARM SCMI PROTOCOL stack to include support for a
+	  transport based on SMC, answer Y.
+	  This driver can also be built as a module. If so, the module
+	  will be called scmi_transport_smc.
+
+config ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE
+	bool "Enable atomic mode support for SCMI SMC transport"
+	depends on ARM_SCMI_TRANSPORT_SMC
+	help
+	  Enable support of atomic operation for SCMI SMC based transport.
+
+	  If you want the SCMI SMC based transport to operate in atomic
+	  mode, avoiding any kind of sleeping behaviour for selected
+	  transactions on the TX path, answer Y.
+	  Enabling atomic mode operations allows any SCMI driver using this
+	  transport to optionally ask for atomic SCMI transactions and operate
+	  in atomic context too, at the price of using a number of busy-waiting
+	  primitives all over instead. If unsure say N.
+
 endmenu

drivers/firmware/arm_scmi/transports/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 scmi_transport_mailbox-objs := mailbox.o
 obj-$(CONFIG_ARM_SCMI_TRANSPORT_MAILBOX) += scmi_transport_mailbox.o
+scmi_transport_smc-objs := smc.o
+obj-$(CONFIG_ARM_SCMI_TRANSPORT_SMC) += scmi_transport_smc.o
 
+ifeq ($(CONFIG_THUMB2_KERNEL)$(CONFIG_CC_IS_CLANG),yy)
+# The use of R7 in the SMCCC conflicts with the compiler's use of R7 as a frame
+# pointer in Thumb2 mode, which is forcibly enabled by Clang when profiling
+# hooks are inserted via the -pg switch.
+CFLAGS_REMOVE_smc.o += $(CC_FLAGS_FTRACE)
+endif

drivers/firmware/arm_scmi/smc.c → drivers/firmware/arm_scmi/transports/smc.c

@@ -16,10 +16,11 @@
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/limits.h>
+#include <linux/platform_device.h>
 #include <linux/processor.h>
 #include <linux/slab.h>
 
-#include "common.h"
+#include "../common.h"
 
 /*
  * The shmem address is split into 4K page and offset.
@@ -69,12 +70,14 @@ struct scmi_smc {
 	unsigned long cap_id;
 };
 
+static struct scmi_transport_core_operations *core;
+
 static irqreturn_t smc_msg_done_isr(int irq, void *data)
 {
 	struct scmi_smc *scmi_info = data;
 
-	scmi_rx_callback(scmi_info->cinfo,
-			 scmi_shmem_ops.read_header(scmi_info->shmem), NULL);
+	core->rx_callback(scmi_info->cinfo,
+			  core->shmem->read_header(scmi_info->shmem), NULL);
 
 	return IRQ_HANDLED;
 }
@@ -141,7 +144,7 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
 	if (!scmi_info)
 		return -ENOMEM;
 
-	scmi_info->shmem = scmi_shmem_ops.setup_iomap(cinfo, dev, tx, &res);
+	scmi_info->shmem = core->shmem->setup_iomap(cinfo, dev, tx, &res);
 	if (IS_ERR(scmi_info->shmem))
 		return PTR_ERR(scmi_info->shmem);
 
@@ -226,7 +229,7 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
 	 */
 	smc_channel_lock_acquire(scmi_info, xfer);
 
-	scmi_shmem_ops.tx_prepare(scmi_info->shmem, xfer, cinfo);
+	core->shmem->tx_prepare(scmi_info->shmem, xfer, cinfo);
 
 	if (scmi_info->cap_id != ULONG_MAX)
 		arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->cap_id, 0,
@@ -250,7 +253,7 @@ static void smc_fetch_response(struct scmi_chan_info *cinfo,
 {
 	struct scmi_smc *scmi_info = cinfo->transport_info;
 
-	scmi_shmem_ops.fetch_response(scmi_info->shmem, xfer);
+	core->shmem->fetch_response(scmi_info->shmem, xfer);
 }
 
 static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
@@ -270,7 +273,7 @@ static const struct scmi_transport_ops scmi_smc_ops = {
 	.fetch_response = smc_fetch_response,
 };
 
-const struct scmi_desc scmi_smc_desc = {
+static const struct scmi_desc scmi_smc_desc = {
 	.ops = &scmi_smc_ops,
 	.max_rx_timeout_ms = 30,
 	.max_msg = 20,
@@ -286,3 +289,19 @@ const struct scmi_desc scmi_smc_desc = {
 	.sync_cmds_completed_on_ret = true,
 	.atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
 };
+
+static const struct of_device_id scmi_of_match[] = {
+	{ .compatible = "arm,scmi-smc" },
+	{ .compatible = "arm,scmi-smc-param" },
+	{ .compatible = "qcom,scmi-smc" },
+	{ /* Sentinel */ },
+};
+
+DEFINE_SCMI_TRANSPORT_DRIVER(scmi_smc, scmi_smc_driver, scmi_smc_desc,
+			     scmi_of_match, core);
+module_platform_driver(scmi_smc_driver);
+
+MODULE_AUTHOR("Peng Fan <peng.fan@nxp.com>");
+MODULE_AUTHOR("Nikunj Kela <quic_nkela@quicinc.com>");
+MODULE_DESCRIPTION("SCMI SMC Transport driver");
+MODULE_LICENSE("GPL");