/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_VIRTIO_CONFIG_H
#define _LINUX_VIRTIO_CONFIG_H

#include <linux/err.h>
#include <linux/bug.h>
#include <linux/virtio.h>
#include <linux/virtio_byteorder.h>
#include <uapi/linux/virtio_config.h>

struct irq_affinity;

/**
 * virtio_config_ops - operations for configuring a virtio device
 * Note: Do not assume that a transport implements all of the operations
 *       getting/setting a value as a simple read/write! Generally speaking,
 *       any of @get/@set, @get_status/@set_status, or @get_features/
 *       @finalize_features are NOT safe to be called from an atomic
 *       context.
 * @get: read the value of a configuration field
 *      vdev: the virtio_device
 *      offset: the offset of the configuration field
 *      buf: the buffer to write the field value into.
 *      len: the length of the buffer
 * @set: write the value of a configuration field
 *      vdev: the virtio_device
 *      offset: the offset of the configuration field
 *      buf: the buffer to read the field value from.
 *      len: the length of the buffer
 * @generation: config generation counter (optional)
 *      vdev: the virtio_device
 *      Returns the config generation counter
 * @get_status: read the status byte
 *      vdev: the virtio_device
 *      Returns the status byte
 * @set_status: write the status byte
 *      vdev: the virtio_device
 *      status: the new status byte
 * @reset: reset the device
 *      vdev: the virtio device
 *      After this, status and feature negotiation must be done again
 *      Device must not be reset from its vq/config callbacks, or in
 *      parallel with being added/removed.
 * @find_vqs: find virtqueues and instantiate them.
 *      vdev: the virtio_device
 *      nvqs: the number of virtqueues to find
 *      vqs: on success, includes new virtqueues
 *      callbacks: array of callbacks, for each virtqueue
 *              include a NULL entry for vqs that do not need a callback
 *      names: array of virtqueue names (mainly for debugging)
 *              include a NULL entry for vqs unused by driver
 *      Returns 0 on success or error status
 * @del_vqs: free virtqueues found by find_vqs().
 * @get_features: get the array of feature bits for this device.
 *      vdev: the virtio_device
 *      Returns the first 64 feature bits (all we currently need).
 * @finalize_features: confirm what device features we'll be using.
 *      vdev: the virtio_device
 *      This gives the final feature bits for the device: it can change
 *      the dev->feature bits if it wants.
 *      Returns 0 on success or error status
 * @bus_name: return the bus name associated with the device (optional)
 *      vdev: the virtio_device
 *      This returns a pointer to the bus name a la pci_name from which
 *      the caller can then copy.
 * @set_vq_affinity: set the affinity for a virtqueue (optional).
 * @get_vq_affinity: get the affinity for a virtqueue (optional).
 */
typedef void vq_callback_t(struct virtqueue *);
struct virtio_config_ops {
        void (*get)(struct virtio_device *vdev, unsigned offset,
                    void *buf, unsigned len);
        void (*set)(struct virtio_device *vdev, unsigned offset,
                    const void *buf, unsigned len);
        u32 (*generation)(struct virtio_device *vdev);
        u8 (*get_status)(struct virtio_device *vdev);
        void (*set_status)(struct virtio_device *vdev, u8 status);
        void (*reset)(struct virtio_device *vdev);
        int (*find_vqs)(struct virtio_device *, unsigned nvqs,
                        struct virtqueue *vqs[], vq_callback_t *callbacks[],
                        const char * const names[], const bool *ctx,
                        struct irq_affinity *desc);
        void (*del_vqs)(struct virtio_device *);
        u64 (*get_features)(struct virtio_device *vdev);
        int (*finalize_features)(struct virtio_device *vdev);
        const char *(*bus_name)(struct virtio_device *vdev);
        int (*set_vq_affinity)(struct virtqueue *vq,
                               const struct cpumask *cpu_mask);
        const struct cpumask *(*get_vq_affinity)(struct virtio_device *vdev,
                        int index);
};

/* If driver didn't advertise the feature, it will never appear. */
void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
                                         unsigned int fbit);

/**
 * __virtio_test_bit - helper to test feature bits. For use by transports.
 *                     Devices should normally use virtio_has_feature,
 *                     which includes more checks.
 * @vdev: the device
 * @fbit: the feature bit
 */
static inline bool __virtio_test_bit(const struct virtio_device *vdev,
                                     unsigned int fbit)
{
        /* Did you forget to fix assumptions on max features? */
        if (__builtin_constant_p(fbit))
                BUILD_BUG_ON(fbit >= 64);
        else
                BUG_ON(fbit >= 64);

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

/**
 * __virtio_set_bit - helper to set feature bits. For use by transports.
 * @vdev: the device
 * @fbit: the feature bit
 */
static inline void __virtio_set_bit(struct virtio_device *vdev,
                                    unsigned int fbit)
{
        /* Did you forget to fix assumptions on max features? */
        if (__builtin_constant_p(fbit))
                BUILD_BUG_ON(fbit >= 64);
        else
                BUG_ON(fbit >= 64);

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

/**
 * __virtio_clear_bit - helper to clear feature bits. For use by transports.
 * @vdev: the device
 * @fbit: the feature bit
 */
static inline void __virtio_clear_bit(struct virtio_device *vdev,
                                      unsigned int fbit)
{
        /* Did you forget to fix assumptions on max features? */
        if (__builtin_constant_p(fbit))
                BUILD_BUG_ON(fbit >= 64);
        else
                BUG_ON(fbit >= 64);

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

/**
 * virtio_has_feature - helper to determine if this device has this feature.
 * @vdev: the device
 * @fbit: the feature bit
 */
static inline bool virtio_has_feature(const struct virtio_device *vdev,
                                      unsigned int fbit)
{
        if (fbit < VIRTIO_TRANSPORT_F_START)
                virtio_check_driver_offered_feature(vdev, fbit);

        return __virtio_test_bit(vdev, fbit);
}

/**
 * virtio_has_iommu_quirk - determine whether this device has the iommu quirk
 * @vdev: the device
 */
static inline bool virtio_has_iommu_quirk(const struct virtio_device *vdev)
{
        /*
         * Note the reverse polarity of the quirk feature (compared to most
         * other features), this is for compatibility with legacy systems.
         */
        return !virtio_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM);
}

static inline
struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
                                        vq_callback_t *c, const char *n)
{
        vq_callback_t *callbacks[] = { c };
        const char *names[] = { n };
        struct virtqueue *vq;
        int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names, NULL,
                                         NULL);
        if (err < 0)
                return ERR_PTR(err);
        return vq;
}

static inline
int virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
                        struct virtqueue *vqs[], vq_callback_t *callbacks[],
                        const char * const names[],
                        struct irq_affinity *desc)
{
        return vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names, NULL, desc);
}

static inline
int virtio_find_vqs_ctx(struct virtio_device *vdev, unsigned nvqs,
                        struct virtqueue *vqs[], vq_callback_t *callbacks[],
                        const char * const names[], const bool *ctx,
                        struct irq_affinity *desc)
{
        return vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names, ctx,
                                      desc);
}

/**
 * virtio_device_ready - enable vq use in probe function
 * @vdev: the device
 *
 * Driver must call this to use vqs in the probe function.
 *
 * Note: vqs are enabled automatically after probe returns.
 */
static inline
void virtio_device_ready(struct virtio_device *dev)
{
        unsigned status = dev->config->get_status(dev);

        BUG_ON(status & VIRTIO_CONFIG_S_DRIVER_OK);
        dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
}

static inline
const char *virtio_bus_name(struct virtio_device *vdev)
{
        if (!vdev->config->bus_name)
                return "virtio";
        return vdev->config->bus_name(vdev);
}

/**
 * virtqueue_set_affinity - setting affinity for a virtqueue
 * @vq: the virtqueue
 * @cpu: the cpu no.
 *
 * Pay attention the function are best-effort: the affinity hint may not be set
 * due to config support, irq type and sharing.
 *
 */
static inline
int virtqueue_set_affinity(struct virtqueue *vq, const struct cpumask *cpu_mask)
{
        struct virtio_device *vdev = vq->vdev;
        if (vdev->config->set_vq_affinity)
                return vdev->config->set_vq_affinity(vq, cpu_mask);
        return 0;
}

static inline bool virtio_is_little_endian(struct virtio_device *vdev)
{
        return virtio_has_feature(vdev, VIRTIO_F_VERSION_1) ||
                virtio_legacy_is_little_endian();
}

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

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

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

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

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

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

/* Config space accessors. */
#define virtio_cread(vdev, structname, member, ptr)                     \
        do {                                                            \
                might_sleep();                                          \
                /* 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:                                                \
                        BUG();                                          \
                }                                                       \
        } while(0)

/* Config space accessors. */
#define virtio_cwrite(vdev, structname, member, ptr)                    \
        do {                                                            \
                might_sleep();                                          \
                /* Must match the member's type, and be integer */      \
                if (!typecheck(typeof((((structname*)0)->member)), *(ptr))) \
                        BUG_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:                                                \
                        BUG();                                          \
                }                                                       \
        } while(0)

/* Read @count fields, @bytes each. */
static inline void __virtio_cread_many(struct virtio_device *vdev,
                                       unsigned int offset,
                                       void *buf, size_t count, size_t bytes)
{
        u32 old, gen = vdev->config->generation ?
                vdev->config->generation(vdev) : 0;
        int i;

        might_sleep();
        do {
                old = gen;

                for (i = 0; i < count; i++)
                        vdev->config->get(vdev, offset + bytes * i,
                                          buf + i * bytes, bytes);

                gen = vdev->config->generation ?
                        vdev->config->generation(vdev) : 0;
        } while (gen != old);
}

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

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

        might_sleep();
        vdev->config->get(vdev, offset, &ret, sizeof(ret));
        return ret;
}

static inline void virtio_cwrite8(struct virtio_device *vdev,
                                  unsigned int offset, u8 val)
{
        might_sleep();
        vdev->config->set(vdev, offset, &val, sizeof(val));
}

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

        might_sleep();
        vdev->config->get(vdev, offset, &ret, sizeof(ret));
        return virtio16_to_cpu(vdev, (__force __virtio16)ret);
}

static inline void virtio_cwrite16(struct virtio_device *vdev,
                                   unsigned int offset, u16 val)
{
        might_sleep();
        val = (__force u16)cpu_to_virtio16(vdev, val);
        vdev->config->set(vdev, offset, &val, sizeof(val));
}

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

        might_sleep();
        vdev->config->get(vdev, offset, &ret, sizeof(ret));
        return virtio32_to_cpu(vdev, (__force __virtio32)ret);
}

static inline void virtio_cwrite32(struct virtio_device *vdev,
                                   unsigned int offset, u32 val)
{
        might_sleep();
        val = (__force u32)cpu_to_virtio32(vdev, val);
        vdev->config->set(vdev, offset, &val, sizeof(val));
}

static inline u64 virtio_cread64(struct virtio_device *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 virtio_device *vdev,
                                   unsigned int offset, u64 val)
{
        might_sleep();
        val = (__force u64)cpu_to_virtio64(vdev, val);
        vdev->config->set(vdev, offset, &val, sizeof(val));
}

/* 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 /* _LINUX_VIRTIO_CONFIG_H */