path: root/drivers/firmware/arm_ffa/driver.c

// 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");