firmware: arm_ffa: Add initial Arm FFA driver support

This just add a basic driver that sets up the transport(e.g. SMCCC),
checks the FFA version implemented, get the partition ID for self and
sets up the Tx/Rx buffers for communication.

Link: https://lore.kernel.org/r/20210521151033.181846-3-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_ffa/Makefile

@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
 ffa-bus-y = bus.o
-ffa-module-objs := $(ffa-bus-y)
+ffa-driver-y = driver.o
+ffa-module-objs := $(ffa-bus-y) $(ffa-driver-y)
 obj-$(CONFIG_ARM_FFA_TRANSPORT) = ffa-module.o

drivers/firmware/arm_ffa/bus.c

@@ -13,6 +13,8 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 
+#include "common.h"
+
 static int ffa_device_match(struct device *dev, struct device_driver *drv)
 {
 	const struct ffa_device_id *id_table;
@@ -187,21 +189,13 @@ void ffa_device_unregister(struct ffa_device *ffa_dev)
 }
 EXPORT_SYMBOL_GPL(ffa_device_unregister);
 
-static int __init arm_ffa_bus_init(void)
+int arm_ffa_bus_init(void)
 {
 	return bus_register(&ffa_bus_type);
 }
-module_init(arm_ffa_bus_init);
 
-static void __exit arm_ffa_bus_exit(void)
+void arm_ffa_bus_exit(void)
 {
 	ffa_devices_unregister();
 	bus_unregister(&ffa_bus_type);
 }
-
-module_exit(arm_ffa_bus_exit);
-
-MODULE_ALIAS("arm-ffa-bus");
-MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
-MODULE_DESCRIPTION("Arm FF-A bus driver");
-MODULE_LICENSE("GPL v2");

drivers/firmware/arm_ffa/common.h

@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2021 ARM Ltd.
+ */
+
+#ifndef _FFA_COMMON_H
+#define _FFA_COMMON_H
+
+#include <linux/arm-smccc.h>
+#include <linux/err.h>
+
+typedef struct arm_smccc_1_2_regs ffa_value_t;
+
+typedef void (ffa_fn)(ffa_value_t, ffa_value_t *);
+
+int arm_ffa_bus_init(void);
+void arm_ffa_bus_exit(void);
+
+static inline int __init ffa_transport_init(ffa_fn **invoke_ffa_fn)
+{
+	return -EOPNOTSUPP;
+}
+
+#endif /* _FFA_COMMON_H */

drivers/firmware/arm_ffa/driver.c

@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Arm Firmware Framework for ARMv8-A(FFA) interface driver
+ *
+ * The Arm FFA specification[1] describes a software architecture to
+ * leverages the virtualization extension to isolate software images
+ * provided by an ecosystem of vendors from each other and describes
+ * interfaces that standardize communication between the various software
+ * images including communication between images in the Secure world and
+ * Normal world. Any Hypervisor could use the FFA interfaces to enable
+ * communication between VMs it manages.
+ *
+ * The Hypervisor a.k.a Partition managers in FFA terminology can assign
+ * system resources(Memory regions, Devices, CPU cycles) to the partitions
+ * and manage isolation amongst them.
+ *
+ * [1] https://developer.arm.com/docs/den0077/latest
+ *
+ * Copyright (C) 2021 ARM Ltd.
+ */
+
+#define DRIVER_NAME "ARM FF-A"
+#define pr_fmt(fmt) DRIVER_NAME ": " fmt
+
+#include <linux/arm_ffa.h>
+#include <linux/bitfield.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "common.h"
+
+#define FFA_DRIVER_VERSION	FFA_VERSION_1_0
+
+#define FFA_SMC(calling_convention, func_num)				\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, (calling_convention),	\
+			   ARM_SMCCC_OWNER_STANDARD, (func_num))
+
+#define FFA_SMC_32(func_num)	FFA_SMC(ARM_SMCCC_SMC_32, (func_num))
+#define FFA_SMC_64(func_num)	FFA_SMC(ARM_SMCCC_SMC_64, (func_num))
+
+#define FFA_ERROR			FFA_SMC_32(0x60)
+#define FFA_SUCCESS			FFA_SMC_32(0x61)
+#define FFA_INTERRUPT			FFA_SMC_32(0x62)
+#define FFA_VERSION			FFA_SMC_32(0x63)
+#define FFA_FEATURES			FFA_SMC_32(0x64)
+#define FFA_RX_RELEASE			FFA_SMC_32(0x65)
+#define FFA_RXTX_MAP			FFA_SMC_32(0x66)
+#define FFA_FN64_RXTX_MAP		FFA_SMC_64(0x66)
+#define FFA_RXTX_UNMAP			FFA_SMC_32(0x67)
+#define FFA_PARTITION_INFO_GET		FFA_SMC_32(0x68)
+#define FFA_ID_GET			FFA_SMC_32(0x69)
+#define FFA_MSG_POLL			FFA_SMC_32(0x6A)
+#define FFA_MSG_WAIT			FFA_SMC_32(0x6B)
+#define FFA_YIELD			FFA_SMC_32(0x6C)
+#define FFA_RUN				FFA_SMC_32(0x6D)
+#define FFA_MSG_SEND			FFA_SMC_32(0x6E)
+#define FFA_MSG_SEND_DIRECT_REQ		FFA_SMC_32(0x6F)
+#define FFA_FN64_MSG_SEND_DIRECT_REQ	FFA_SMC_64(0x6F)
+#define FFA_MSG_SEND_DIRECT_RESP	FFA_SMC_32(0x70)
+#define FFA_FN64_MSG_SEND_DIRECT_RESP	FFA_SMC_64(0x70)
+#define FFA_MEM_DONATE			FFA_SMC_32(0x71)
+#define FFA_FN64_MEM_DONATE		FFA_SMC_64(0x71)
+#define FFA_MEM_LEND			FFA_SMC_32(0x72)
+#define FFA_FN64_MEM_LEND		FFA_SMC_64(0x72)
+#define FFA_MEM_SHARE			FFA_SMC_32(0x73)
+#define FFA_FN64_MEM_SHARE		FFA_SMC_64(0x73)
+#define FFA_MEM_RETRIEVE_REQ		FFA_SMC_32(0x74)
+#define FFA_FN64_MEM_RETRIEVE_REQ	FFA_SMC_64(0x74)
+#define FFA_MEM_RETRIEVE_RESP		FFA_SMC_32(0x75)
+#define FFA_MEM_RELINQUISH		FFA_SMC_32(0x76)
+#define FFA_MEM_RECLAIM			FFA_SMC_32(0x77)
+#define FFA_MEM_OP_PAUSE		FFA_SMC_32(0x78)
+#define FFA_MEM_OP_RESUME		FFA_SMC_32(0x79)
+#define FFA_MEM_FRAG_RX			FFA_SMC_32(0x7A)
+#define FFA_MEM_FRAG_TX			FFA_SMC_32(0x7B)
+#define FFA_NORMAL_WORLD_RESUME		FFA_SMC_32(0x7C)
+
+/*
+ * For some calls it is necessary to use SMC64 to pass or return 64-bit values.
+ * For such calls FFA_FN_NATIVE(name) will choose the appropriate
+ * (native-width) function ID.
+ */
+#ifdef CONFIG_64BIT
+#define FFA_FN_NATIVE(name)	FFA_FN64_##name
+#else
+#define FFA_FN_NATIVE(name)	FFA_##name
+#endif
+
+/* FFA error codes. */
+#define FFA_RET_SUCCESS            (0)
+#define FFA_RET_NOT_SUPPORTED      (-1)
+#define FFA_RET_INVALID_PARAMETERS (-2)
+#define FFA_RET_NO_MEMORY          (-3)
+#define FFA_RET_BUSY               (-4)
+#define FFA_RET_INTERRUPTED        (-5)
+#define FFA_RET_DENIED             (-6)
+#define FFA_RET_RETRY              (-7)
+#define FFA_RET_ABORTED            (-8)
+
+#define MAJOR_VERSION_MASK	GENMASK(30, 16)
+#define MINOR_VERSION_MASK	GENMASK(15, 0)
+#define MAJOR_VERSION(x)	((u16)(FIELD_GET(MAJOR_VERSION_MASK, (x))))
+#define MINOR_VERSION(x)	((u16)(FIELD_GET(MINOR_VERSION_MASK, (x))))
+#define PACK_VERSION_INFO(major, minor)			\
+	(FIELD_PREP(MAJOR_VERSION_MASK, (major)) |	\
+	 FIELD_PREP(MINOR_VERSION_MASK, (minor)))
+#define FFA_VERSION_1_0		PACK_VERSION_INFO(1, 0)
+#define FFA_MIN_VERSION		FFA_VERSION_1_0
+
+#define SENDER_ID_MASK		GENMASK(31, 16)
+#define RECEIVER_ID_MASK	GENMASK(15, 0)
+#define SENDER_ID(x)		((u16)(FIELD_GET(SENDER_ID_MASK, (x))))
+#define RECEIVER_ID(x)		((u16)(FIELD_GET(RECEIVER_ID_MASK, (x))))
+#define PACK_TARGET_INFO(s, r)		\
+	(FIELD_PREP(SENDER_ID_MASK, (s)) | FIELD_PREP(RECEIVER_ID_MASK, (r)))
+
+/**
+ * FF-A specification mentions explicitly about '4K pages'. This should
+ * not be confused with the kernel PAGE_SIZE, which is the translation
+ * granule kernel is configured and may be one among 4K, 16K and 64K.
+ */
+#define FFA_PAGE_SIZE		SZ_4K
+/*
+ * Keeping RX TX buffer size as 4K for now
+ * 64K may be preferred to keep it min a page in 64K PAGE_SIZE config
+ */
+#define RXTX_BUFFER_SIZE	SZ_4K
+
+static ffa_fn *invoke_ffa_fn;
+
+static const int ffa_linux_errmap[] = {
+	/* better than switch case as long as return value is continuous */
+	0,		/* FFA_RET_SUCCESS */
+	-EOPNOTSUPP,	/* FFA_RET_NOT_SUPPORTED */
+	-EINVAL,	/* FFA_RET_INVALID_PARAMETERS */
+	-ENOMEM,	/* FFA_RET_NO_MEMORY */
+	-EBUSY,		/* FFA_RET_BUSY */
+	-EINTR,		/* FFA_RET_INTERRUPTED */
+	-EACCES,	/* FFA_RET_DENIED */
+	-EAGAIN,	/* FFA_RET_RETRY */
+	-ECANCELED,	/* FFA_RET_ABORTED */
+};
+
+static inline int ffa_to_linux_errno(int errno)
+{
+	if (errno < FFA_RET_SUCCESS && errno >= -ARRAY_SIZE(ffa_linux_errmap))
+		return ffa_linux_errmap[-errno];
+	return -EINVAL;
+}
+
+struct ffa_drv_info {
+	u32 version;
+	u16 vm_id;
+	struct mutex rx_lock; /* lock to protect Rx buffer */
+	struct mutex tx_lock; /* lock to protect Tx buffer */
+	void *rx_buffer;
+	void *tx_buffer;
+};
+
+static struct ffa_drv_info *drv_info;
+
+static int ffa_version_check(u32 *version)
+{
+	ffa_value_t ver;
+
+	invoke_ffa_fn((ffa_value_t){
+		      .a0 = FFA_VERSION, .a1 = FFA_DRIVER_VERSION,
+		      }, &ver);
+
+	if (ver.a0 == FFA_RET_NOT_SUPPORTED) {
+		pr_info("FFA_VERSION returned not supported\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (ver.a0 < FFA_MIN_VERSION || ver.a0 > FFA_DRIVER_VERSION) {
+		pr_err("Incompatible version %d.%d found\n",
+		       MAJOR_VERSION(ver.a0), MINOR_VERSION(ver.a0));
+		return -EINVAL;
+	}
+
+	*version = ver.a0;
+	pr_info("Version %d.%d found\n", MAJOR_VERSION(ver.a0),
+		MINOR_VERSION(ver.a0));
+	return 0;
+}
+
+static int ffa_rxtx_map(phys_addr_t tx_buf, phys_addr_t rx_buf, u32 pg_cnt)
+{
+	ffa_value_t ret;
+
+	invoke_ffa_fn((ffa_value_t){
+		      .a0 = FFA_FN_NATIVE(RXTX_MAP),
+		      .a1 = tx_buf, .a2 = rx_buf, .a3 = pg_cnt,
+		      }, &ret);
+
+	if (ret.a0 == FFA_ERROR)
+		return ffa_to_linux_errno((int)ret.a2);
+
+	return 0;
+}
+
+static int ffa_rxtx_unmap(u16 vm_id)
+{
+	ffa_value_t ret;
+
+	invoke_ffa_fn((ffa_value_t){
+		      .a0 = FFA_RXTX_UNMAP, .a1 = PACK_TARGET_INFO(vm_id, 0),
+		      }, &ret);
+
+	if (ret.a0 == FFA_ERROR)
+		return ffa_to_linux_errno((int)ret.a2);
+
+	return 0;
+}
+
+#define VM_ID_MASK	GENMASK(15, 0)
+static int ffa_id_get(u16 *vm_id)
+{
+	ffa_value_t id;
+
+	invoke_ffa_fn((ffa_value_t){
+		      .a0 = FFA_ID_GET,
+		      }, &id);
+
+	if (id.a0 == FFA_ERROR)
+		return ffa_to_linux_errno((int)id.a2);
+
+	*vm_id = FIELD_GET(VM_ID_MASK, (id.a2));
+
+	return 0;
+}
+
+static int __init ffa_init(void)
+{
+	int ret;
+
+	ret = ffa_transport_init(&invoke_ffa_fn);
+	if (ret)
+		return ret;
+
+	ret = arm_ffa_bus_init();
+	if (ret)
+		return ret;
+
+	drv_info = kzalloc(sizeof(*drv_info), GFP_KERNEL);
+	if (!drv_info) {
+		ret = -ENOMEM;
+		goto ffa_bus_exit;
+	}
+
+	ret = ffa_version_check(&drv_info->version);
+	if (ret)
+		goto free_drv_info;
+
+	if (ffa_id_get(&drv_info->vm_id)) {
+		pr_err("failed to obtain VM id for self\n");
+		ret = -ENODEV;
+		goto free_drv_info;
+	}
+
+	drv_info->rx_buffer = alloc_pages_exact(RXTX_BUFFER_SIZE, GFP_KERNEL);
+	if (!drv_info->rx_buffer) {
+		ret = -ENOMEM;
+		goto free_pages;
+	}
+
+	drv_info->tx_buffer = alloc_pages_exact(RXTX_BUFFER_SIZE, GFP_KERNEL);
+	if (!drv_info->tx_buffer) {
+		ret = -ENOMEM;
+		goto free_pages;
+	}
+
+	ret = ffa_rxtx_map(virt_to_phys(drv_info->tx_buffer),
+			   virt_to_phys(drv_info->rx_buffer),
+			   RXTX_BUFFER_SIZE / FFA_PAGE_SIZE);
+	if (ret) {
+		pr_err("failed to register FFA RxTx buffers\n");
+		goto free_pages;
+	}
+
+	mutex_init(&drv_info->rx_lock);
+	mutex_init(&drv_info->tx_lock);
+
+	return 0;
+free_pages:
+	if (drv_info->tx_buffer)
+		free_pages_exact(drv_info->tx_buffer, RXTX_BUFFER_SIZE);
+	free_pages_exact(drv_info->rx_buffer, RXTX_BUFFER_SIZE);
+free_drv_info:
+	kfree(drv_info);
+ffa_bus_exit:
+	arm_ffa_bus_exit();
+	return ret;
+}
+subsys_initcall(ffa_init);
+
+static void __exit ffa_exit(void)
+{
+	ffa_rxtx_unmap(drv_info->vm_id);
+	free_pages_exact(drv_info->tx_buffer, RXTX_BUFFER_SIZE);
+	free_pages_exact(drv_info->rx_buffer, RXTX_BUFFER_SIZE);
+	kfree(drv_info);
+	arm_ffa_bus_exit();
+}
+module_exit(ffa_exit);
+
+MODULE_ALIAS("arm-ffa");
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("Arm FF-A interface driver");
+MODULE_LICENSE("GPL v2");