/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
 * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
 *
 * VirtIO is a virtualization standard for network and disk device drivers
 * where just the guest's device driver "knows" it is running in a virtual
 * environment, and cooperates with the hypervisor. This enables guests to
 * get high performance network and disk operations, and gives most of the
 * performance benefits of paravirtualization. In the U-Boot case, the guest
 * is U-Boot itself, while the virtual environment are normally QEMU targets
 * like ARM, RISC-V and x86.
 *
 * See http://docs.oasis-open.org/virtio/virtio/v1.0/virtio-v1.0.pdf for
 * the VirtIO specification v1.0.
 *
 * This file is largely based on Linux kernel virtio_*.h files
 */

#ifndef __VIRTIO_H__
#define __VIRTIO_H__

#define VIRTIO_ID_NET           1 /* virtio net */
#define VIRTIO_ID_BLOCK         2 /* virtio block */
#define VIRTIO_ID_MAX_NUM       3

#define VIRTIO_NET_DRV_NAME     "virtio-net"
#define VIRTIO_BLK_DRV_NAME     "virtio-blk"

/* Status byte for guest to report progress, and synchronize features */

/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
#define VIRTIO_CONFIG_S_ACKNOWLEDGE     1
/* We have found a driver for the device */
#define VIRTIO_CONFIG_S_DRIVER          2
/* Driver has used its parts of the config, and is happy */
#define VIRTIO_CONFIG_S_DRIVER_OK       4
/* Driver has finished configuring features */
#define VIRTIO_CONFIG_S_FEATURES_OK     8
/* Device entered invalid state, driver must reset it */
#define VIRTIO_CONFIG_S_NEEDS_RESET     0x40
/* We've given up on this device */
#define VIRTIO_CONFIG_S_FAILED          0x80

/*
 * Virtio feature bits VIRTIO_TRANSPORT_F_START through VIRTIO_TRANSPORT_F_END
 * are reserved for the transport being used (eg: virtio_ring, virtio_pci etc.),
 * the rest are per-device feature bits.
 */
#define VIRTIO_TRANSPORT_F_START        28
#define VIRTIO_TRANSPORT_F_END          38

#ifndef VIRTIO_CONFIG_NO_LEGACY
/*
 * Do we get callbacks when the ring is completely used,
 * even if we've suppressed them?
 */
#define VIRTIO_F_NOTIFY_ON_EMPTY        24

/* Can the device handle any descriptor layout? */
#define VIRTIO_F_ANY_LAYOUT             27
#endif /* VIRTIO_CONFIG_NO_LEGACY */

/* v1.0 compliant */
#define VIRTIO_F_VERSION_1              32

/*
 * If clear - device has the IOMMU bypass quirk feature.
 * If set - use platform tools to detect the IOMMU.
 *
 * Note the reverse polarity (compared to most other features),
 * this is for compatibility with legacy systems.
 */
#define VIRTIO_F_IOMMU_PLATFORM         33

/* Does the device support Single Root I/O Virtualization? */
#define VIRTIO_F_SR_IOV                 37

/**
 * virtio scatter-gather struct
 *
 * @addr:               sg buffer address
 * @lengh:              sg buffer length
 */
struct virtio_sg {
        void *addr;
        size_t length;
};

struct virtqueue;

/* virtio bus operations */
struct dm_virtio_ops {
        /**
         * get_config() - read the value of a configuration field
         *
         * @vdev:       the real virtio device
         * @offset:     the offset of the configuration field
         * @buf:        the buffer to write the field value into
         * @len:        the length of the buffer
         * @return 0 if OK, -ve on error
         */
        int (*get_config)(struct udevice *vdev, unsigned int offset,
                          void *buf, unsigned int len);
        /**
         * set_config() - write the value of a configuration field
         *
         * @vdev:       the real virtio device
         * @offset:     the offset of the configuration field
         * @buf:        the buffer to read the field value from
         * @len:        the length of the buffer
         * @return 0 if OK, -ve on error
         */
        int (*set_config)(struct udevice *vdev, unsigned int offset,
                          const void *buf, unsigned int len);
        /**
         * generation() - config generation counter
         *
         * @vdev:       the real virtio device
         * @counter:    the returned config generation counter
         * @return 0 if OK, -ve on error
         */
        int (*generation)(struct udevice *vdev, u32 *counter);
        /**
         * get_status() - read the status byte
         *
         * @vdev:       the real virtio device
         * @status:     the returned status byte
         * @return 0 if OK, -ve on error
         */
        int (*get_status)(struct udevice *vdev, u8 *status);
        /**
         * set_status() - write the status byte
         *
         * @vdev:       the real virtio device
         * @status:     the new status byte
         * @return 0 if OK, -ve on error
         */
        int (*set_status)(struct udevice *vdev, u8 status);
        /**
         * reset() - reset the device
         *
         * @vdev:       the real virtio device
         * @return 0 if OK, -ve on error
         */
        int (*reset)(struct udevice *vdev);
        /**
         * get_features() - get the array of feature bits for this device
         *
         * @vdev:       the real virtio device
         * @features:   the first 32 feature bits (all we currently need)
         * @return 0 if OK, -ve on error
         */
        int (*get_features)(struct udevice *vdev, u64 *features);
        /**
         * set_features() - confirm what device features we'll be using
         *
         * @vdev:       the real virtio device
         * @return 0 if OK, -ve on error
         */
        int (*set_features)(struct udevice *vdev);
        /**
         * find_vqs() - find virtqueues and instantiate them
         *
         * @vdev:       the real virtio device
         * @nvqs:       the number of virtqueues to find
         * @vqs:        on success, includes new virtqueues
         * @return 0 if OK, -ve on error
         */
        int (*find_vqs)(struct udevice *vdev, unsigned int nvqs,
                        struct virtqueue *vqs[]);
        /**
         * del_vqs() - free virtqueues found by find_vqs()
         *
         * @vdev:       the real virtio device
         * @return 0 if OK, -ve on error
         */
        int (*del_vqs)(struct udevice *vdev);
        /**
         * notify() - notify the device to process the queue
         *
         * @vdev:       the real virtio device
         * @vq:         virtqueue to process
         * @return 0 if OK, -ve on error
         */
        int (*notify)(struct udevice *vdev, struct virtqueue *vq);
};

/* Get access to a virtio bus' operations */
#define virtio_get_ops(dev)     ((struct dm_virtio_ops *)(dev)->driver->ops)

/**
 * virtio uclass per device private data
 *
 * @vqs:                        virtualqueue for the virtio device
 * @vdev:                       the real virtio device underneath
 * @legacy:                     is it a legacy device?
 * @device:                     virtio device ID
 * @vendor:                     virtio vendor ID
 * @features:                   negotiated supported features
 * @feature_table:              an array of feature supported by the driver
 * @feature_table_size:         number of entries in the feature table array
 * @feature_table_legacy:       same as feature_table but working in legacy mode
 * @feature_table_size_legacy:  number of entries in feature table legacy array
 */
struct virtio_dev_priv {
        struct list_head vqs;
        struct udevice *vdev;
        bool legacy;
        u32 device;
        u32 vendor;
        u64 features;
        const u32 *feature_table;
        u32 feature_table_size;
        const u32 *feature_table_legacy;
        u32 feature_table_size_legacy;
};

/**
 * virtio_get_config() - read the value of a configuration field
 *
 * @vdev:       the real virtio device
 * @offset:     the offset of the configuration field
 * @buf:        the buffer to write the field value into
 * @len:        the length of the buffer
 * @return 0 if OK, -ve on error
 */
int virtio_get_config(struct udevice *vdev, unsigned int offset,
                      void *buf, unsigned int len);

/**
 * virtio_set_config() - write the value of a configuration field
 *
 * @vdev:       the real virtio device
 * @offset:     the offset of the configuration field
 * @buf:        the buffer to read the field value from
 * @len:        the length of the buffer
 * @return 0 if OK, -ve on error
 */
int virtio_set_config(struct udevice *vdev, unsigned int offset,
                      void *buf, unsigned int len);

/**
 * virtio_generation() - config generation counter
 *
 * @vdev:       the real virtio device
 * @counter:    the returned config generation counter
 * @return 0 if OK, -ve on error
 */
int virtio_generation(struct udevice *vdev, u32 *counter);

/**
 * virtio_get_status() - read the status byte
 *
 * @vdev:       the real virtio device
 * @status:     the returned status byte
 * @return 0 if OK, -ve on error
 */
int virtio_get_status(struct udevice *vdev, u8 *status);

/**
 * virtio_set_status() - write the status byte
 *
 * @vdev:       the real virtio device
 * @status:     the new status byte
 * @return 0 if OK, -ve on error
 */
int virtio_set_status(struct udevice *vdev, u8 status);

/**
 * virtio_reset() - reset the device
 *
 * @vdev:       the real virtio device
 * @return 0 if OK, -ve on error
 */
int virtio_reset(struct udevice *vdev);

/**
 * virtio_get_features() - get the array of feature bits for this device
 *
 * @vdev:       the real virtio device
 * @features:   the first 32 feature bits (all we currently need)
 * @return 0 if OK, -ve on error
 */
int virtio_get_features(struct udevice *vdev, u64 *features);

/**
 * virtio_set_features() - confirm what device features we'll be using
 *
 * @vdev:       the real virtio device
 * @return 0 if OK, -ve on error
 */
int virtio_set_features(struct udevice *vdev);

/**
 * virtio_find_vqs() - find virtqueues and instantiate them
 *
 * @vdev:       the real virtio device
 * @nvqs:       the number of virtqueues to find
 * @vqs:        on success, includes new virtqueues
 * @return 0 if OK, -ve on error
 */
int virtio_find_vqs(struct udevice *vdev, unsigned int nvqs,
                    struct virtqueue *vqs[]);

/**
 * virtio_del_vqs() - free virtqueues found by find_vqs()
 *
 * @vdev:       the real virtio device
 * @return 0 if OK, -ve on error
 */
int virtio_del_vqs(struct udevice *vdev);

/**
 * virtio_notify() - notify the device to process the queue
 *
 * @vdev:       the real virtio device
 * @vq:         virtqueue to process
 * @return 0 if OK, -ve on error
 */
int virtio_notify(struct udevice *vdev, struct virtqueue *vq);

/**
 * virtio_add_status() - helper to set a new status code to the device
 *
 * @vdev:       the real virtio device
 * @status:     new status code to be added
 */
void virtio_add_status(struct udevice *vdev, u8 status);

/**
 * virtio_finalize_features() - helper to finalize features
 *
 * @vdev:       the real virtio device
 * @return 0 if OK, -ve on error
 */
int virtio_finalize_features(struct udevice *vdev);

/**
 * virtio_driver_features_init() - initialize driver supported features
 *
 * This fills in the virtio device parent per child private data with the given
 * information, which contains driver supported features and legacy features.
 *
 * This API should be called in the virtio device driver's bind method, so that
 * later virtio transport uclass driver can utilize the driver supplied features
 * to negotiate with the device on the final supported features.
 *
 * @priv:               virtio uclass per device private data
 * @feature:            an array of feature supported by the driver
 * @feature_size:       number of entries in the feature table array
 * @feature_legacy:     same as feature_table but working in legacy mode
 * @feature_legacy_size:number of entries in feature table legacy array
 */
void virtio_driver_features_init(struct virtio_dev_priv *priv,
                                 const u32 *feature,
                                 u32 feature_size,
                                 const u32 *feature_legacy,
                                 u32 feature_legacy_size);

/**
 * virtio_init() - helper to enumerate all known virtio devices
 *
 * @return 0 if OK, -ve on error
 */
int virtio_init(void);

static inline u16 __virtio16_to_cpu(bool little_endian, __virtio16 val)
{
        if (little_endian)
                return le16_to_cpu((__force __le16)val);
        else
                return be16_to_cpu((__force __be16)val);
}

static inline __virtio16 __cpu_to_virtio16(bool little_endian, u16 val)
{
        if (little_endian)
                return (__force __virtio16)cpu_to_le16(val);
        else
                return (__force __virtio16)cpu_to_be16(val);
}

static inline u32 __virtio32_to_cpu(bool little_endian, __virtio32 val)
{
        if (little_endian)
                return le32_to_cpu((__force __le32)val);
        else
                return be32_to_cpu((__force __be32)val);
}

static inline __virtio32 __cpu_to_virtio32(bool little_endian, u32 val)
{
        if (little_endian)
                return (__force __virtio32)cpu_to_le32(val);
        else
                return (__force __virtio32)cpu_to_be32(val);
}

static inline u64 __virtio64_to_cpu(bool little_endian, __virtio64 val)
{
        if (little_endian)
                return le64_to_cpu((__force __le64)val);
        else
                return be64_to_cpu((__force __be64)val);
}

static inline __virtio64 __cpu_to_virtio64(bool little_endian, u64 val)
{
        if (little_endian)
                return (__force __virtio64)cpu_to_le64(val);
        else
                return (__force __virtio64)cpu_to_be64(val);
}

/**
 * __virtio_test_bit - helper to test feature bits
 *
 * For use by transports. Devices should normally use virtio_has_feature,
 * which includes more checks.
 *
 * @udev: the transport device
 * @fbit: the feature bit
 */
static inline bool __virtio_test_bit(struct udevice *udev, unsigned int fbit)
{
        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);

        /* Did you forget to fix assumptions on max features? */
        if (__builtin_constant_p(fbit))
                BUILD_BUG_ON(fbit >= 64);
        else
                WARN_ON(fbit >= 64);

        return uc_priv->features & BIT_ULL(fbit);
}

/**
 * __virtio_set_bit - helper to set feature bits
 *
 * For use by transports.
 *
 * @udev: the transport device
 * @fbit: the feature bit
 */
static inline void __virtio_set_bit(struct udevice *udev, unsigned int fbit)
{
        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);

        /* Did you forget to fix assumptions on max features? */
        if (__builtin_constant_p(fbit))
                BUILD_BUG_ON(fbit >= 64);
        else
                WARN_ON(fbit >= 64);

        uc_priv->features |= BIT_ULL(fbit);
}

/**
 * __virtio_clear_bit - helper to clear feature bits
 *
 * For use by transports.
 *
 * @vdev: the transport device
 * @fbit: the feature bit
 */
static inline void __virtio_clear_bit(struct udevice *udev, unsigned int fbit)
{
        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);

        /* Did you forget to fix assumptions on max features? */
        if (__builtin_constant_p(fbit))
                BUILD_BUG_ON(fbit >= 64);
        else
                WARN_ON(fbit >= 64);

        uc_priv->features &= ~BIT_ULL(fbit);
}

/**
 * virtio_has_feature - helper to determine if this device has this feature
 *
 * Note this API is only usable after the virtio device driver's bind phase,
 * as the feature has been negotiated between the device and the driver.
 *
 * @vdev: the virtio device
 * @fbit: the feature bit
 */
static inline bool virtio_has_feature(struct udevice *vdev, unsigned int fbit)
{
        if (!(vdev->flags & DM_FLAG_BOUND))
                WARN_ON(true);

        return __virtio_test_bit(vdev->parent, fbit);
}

static inline bool virtio_legacy_is_little_endian(void)
{
#ifdef __LITTLE_ENDIAN
        return true;
#else
        return false;
#endif
}

static inline bool virtio_is_little_endian(struct udevice *vdev)
{
        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(vdev->parent);

        return !uc_priv->legacy || virtio_legacy_is_little_endian();
}

/* Memory accessors */
static inline u16 virtio16_to_cpu(struct udevice *vdev, __virtio16 val)
{
        return __virtio16_to_cpu(virtio_is_little_endian(vdev), val);
}

static inline __virtio16 cpu_to_virtio16(struct udevice *vdev, u16 val)
{
        return __cpu_to_virtio16(virtio_is_little_endian(vdev), val);
}

static inline u32 virtio32_to_cpu(struct udevice *vdev, __virtio32 val)
{
        return __virtio32_to_cpu(virtio_is_little_endian(vdev), val);
}

static inline __virtio32 cpu_to_virtio32(struct udevice *vdev, u32 val)
{
        return __cpu_to_virtio32(virtio_is_little_endian(vdev), val);
}

static inline u64 virtio64_to_cpu(struct udevice *vdev, __virtio64 val)
{
        return __virtio64_to_cpu(virtio_is_little_endian(vdev), val);
}

static inline __virtio64 cpu_to_virtio64(struct udevice *vdev, u64 val)
{
        return __cpu_to_virtio64(virtio_is_little_endian(vdev), val);
}

/* Read @count fields, @bytes each */
static inline void __virtio_cread_many(struct udevice *vdev,
                                       unsigned int offset,
                                       void *buf, size_t count, size_t bytes)
{
        u32 old, gen;
        int i;

        /* no need to check return value as generation can be optional */
        virtio_generation(vdev, &gen);
        do {
                old = gen;

                for (i = 0; i < count; i++)
                        virtio_get_config(vdev, offset + bytes * i,
                                          buf + i * bytes, bytes);

                virtio_generation(vdev, &gen);
        } while (gen != old);
}

static inline void virtio_cread_bytes(struct udevice *vdev,
                                      unsigned int offset,
                                      void *buf, size_t len)
{
        __virtio_cread_many(vdev, offset, buf, len, 1);
}

static inline u8 virtio_cread8(struct udevice *vdev, unsigned int offset)
{
        u8 ret;

        virtio_get_config(vdev, offset, &ret, sizeof(ret));
        return ret;
}

static inline void virtio_cwrite8(struct udevice *vdev,
                                  unsigned int offset, u8 val)
{
        virtio_set_config(vdev, offset, &val, sizeof(val));
}

static inline u16 virtio_cread16(struct udevice *vdev,
                                 unsigned int offset)
{
        u16 ret;

        virtio_get_config(vdev, offset, &ret, sizeof(ret));
        return virtio16_to_cpu(vdev, (__force __virtio16)ret);
}

static inline void virtio_cwrite16(struct udevice *vdev,
                                   unsigned int offset, u16 val)
{
        val = (__force u16)cpu_to_virtio16(vdev, val);
        virtio_set_config(vdev, offset, &val, sizeof(val));
}

static inline u32 virtio_cread32(struct udevice *vdev,
                                 unsigned int offset)
{
        u32 ret;

        virtio_get_config(vdev, offset, &ret, sizeof(ret));
        return virtio32_to_cpu(vdev, (__force __virtio32)ret);
}

static inline void virtio_cwrite32(struct udevice *vdev,
                                   unsigned int offset, u32 val)
{
        val = (__force u32)cpu_to_virtio32(vdev, val);
        virtio_set_config(vdev, offset, &val, sizeof(val));
}

static inline u64 virtio_cread64(struct udevice *vdev,
                                 unsigned int offset)
{
        u64 ret;

        __virtio_cread_many(vdev, offset, &ret, 1, sizeof(ret));
        return virtio64_to_cpu(vdev, (__force __virtio64)ret);
}

static inline void virtio_cwrite64(struct udevice *vdev,
                                   unsigned int offset, u64 val)
{
        val = (__force u64)cpu_to_virtio64(vdev, val);
        virtio_set_config(vdev, offset, &val, sizeof(val));
}

/* Config space read accessor */
#define virtio_cread(vdev, structname, member, ptr)                     \
        do {                                                            \
                /* Must match the member's type, and be integer */      \
                if (!typecheck(typeof((((structname *)0)->member)), *(ptr))) \
                        (*ptr) = 1;                                     \
                                                                        \
                switch (sizeof(*ptr)) {                                 \
                case 1:                                                 \
                        *(ptr) = virtio_cread8(vdev,                    \
                                               offsetof(structname, member)); \
                        break;                                          \
                case 2:                                                 \
                        *(ptr) = virtio_cread16(vdev,                   \
                                                offsetof(structname, member)); \
                        break;                                          \
                case 4:                                                 \
                        *(ptr) = virtio_cread32(vdev,                   \
                                                offsetof(structname, member)); \
                        break;                                          \
                case 8:                                                 \
                        *(ptr) = virtio_cread64(vdev,                   \
                                                offsetof(structname, member)); \
                        break;                                          \
                default:                                                \
                        WARN_ON(true);                                  \
                }                                                       \
        } while (0)

/* Config space write accessor */
#define virtio_cwrite(vdev, structname, member, ptr)                    \
        do {                                                            \
                /* Must match the member's type, and be integer */      \
                if (!typecheck(typeof((((structname *)0)->member)), *(ptr))) \
                        WARN_ON((*ptr) == 1);                           \
                                                                        \
                switch (sizeof(*ptr)) {                                 \
                case 1:                                                 \
                        virtio_cwrite8(vdev,                            \
                                       offsetof(structname, member),    \
                                       *(ptr));                         \
                        break;                                          \
                case 2:                                                 \
                        virtio_cwrite16(vdev,                           \
                                        offsetof(structname, member),   \
                                        *(ptr));                        \
                        break;                                          \
                case 4:                                                 \
                        virtio_cwrite32(vdev,                           \
                                        offsetof(structname, member),   \
                                        *(ptr));                        \
                        break;                                          \
                case 8:                                                 \
                        virtio_cwrite64(vdev,                           \
                                        offsetof(structname, member),   \
                                        *(ptr));                        \
                        break;                                          \
                default:                                                \
                        WARN_ON(true);                                  \
                }                                                       \
        } while (0)

/* Conditional config space accessors */
#define virtio_cread_feature(vdev, fbit, structname, member, ptr)       \
        ({                                                              \
                int _r = 0;                                             \
                if (!virtio_has_feature(vdev, fbit))                    \
                        _r = -ENOENT;                                   \
                else                                                    \
                        virtio_cread(vdev, structname, member, ptr);    \
                _r;                                                     \
        })

#endif /* __VIRTIO_H__ */