// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>

#include <uapi/linux/virtio_ids.h>
#include <uapi/linux/virtio_input.h>
#include <linux/input/mt.h>

struct virtio_input {
        struct virtio_device       *vdev;
        struct input_dev           *idev;
        char                       name[64];
        char                       serial[64];
        char                       phys[64];
        struct virtqueue           *evt, *sts;
        __dma_from_device_group_begin();
        struct virtio_input_event  evts[64];
        __dma_from_device_group_end();
        spinlock_t                 lock;
        bool                       ready;
};

static void virtinput_queue_evtbuf(struct virtio_input *vi,
                                   struct virtio_input_event *evtbuf)
{
        struct scatterlist sg[1];

        sg_init_one(sg, evtbuf, sizeof(*evtbuf));
        virtqueue_add_inbuf_cache_clean(vi->evt, sg, 1, evtbuf, GFP_ATOMIC);
}

static void virtinput_recv_events(struct virtqueue *vq)
{
        struct virtio_input *vi = vq->vdev->priv;
        struct virtio_input_event *event;
        unsigned long flags;
        unsigned int len;

        spin_lock_irqsave(&vi->lock, flags);
        if (vi->ready) {
                while ((event = virtqueue_get_buf(vi->evt, &len)) != NULL) {
                        spin_unlock_irqrestore(&vi->lock, flags);
                        input_event(vi->idev,
                                    le16_to_cpu(event->type),
                                    le16_to_cpu(event->code),
                                    le32_to_cpu(event->value));
                        spin_lock_irqsave(&vi->lock, flags);
                        virtinput_queue_evtbuf(vi, event);
                }
                virtqueue_kick(vq);
        }
        spin_unlock_irqrestore(&vi->lock, flags);
}

/*
 * On error we are losing the status update, which isn't critical as
 * this is typically used for stuff like keyboard leds.
 */
static int virtinput_send_status(struct virtio_input *vi,
                                 u16 type, u16 code, s32 value)
{
        struct virtio_input_event *stsbuf;
        struct scatterlist sg[1];
        unsigned long flags;
        int rc;

        /*
         * Since 29cc309d8bf1 (HID: hid-multitouch: forward MSC_TIMESTAMP),
         * EV_MSC/MSC_TIMESTAMP is added to each before EV_SYN event.
         * EV_MSC is configured as INPUT_PASS_TO_ALL.
         * In case of touch device:
         *   BE pass EV_MSC/MSC_TIMESTAMP to FE on receiving event from evdev.
         *   FE pass EV_MSC/MSC_TIMESTAMP back to BE.
         *   BE writes EV_MSC/MSC_TIMESTAMP to evdev due to INPUT_PASS_TO_ALL.
         *   BE receives extra EV_MSC/MSC_TIMESTAMP and pass to FE.
         *   >>> Each new frame becomes larger and larger.
         * Disable EV_MSC/MSC_TIMESTAMP forwarding for MT.
         */
        if (vi->idev->mt && type == EV_MSC && code == MSC_TIMESTAMP)
                return 0;

        stsbuf = kzalloc_obj(*stsbuf, GFP_ATOMIC);
        if (!stsbuf)
                return -ENOMEM;

        stsbuf->type  = cpu_to_le16(type);
        stsbuf->code  = cpu_to_le16(code);
        stsbuf->value = cpu_to_le32(value);
        sg_init_one(sg, stsbuf, sizeof(*stsbuf));

        spin_lock_irqsave(&vi->lock, flags);
        if (vi->ready) {
                rc = virtqueue_add_outbuf(vi->sts, sg, 1, stsbuf, GFP_ATOMIC);
                virtqueue_kick(vi->sts);
        } else {
                rc = -ENODEV;
        }
        spin_unlock_irqrestore(&vi->lock, flags);

        if (rc != 0)
                kfree(stsbuf);
        return rc;
}

static void virtinput_recv_status(struct virtqueue *vq)
{
        struct virtio_input *vi = vq->vdev->priv;
        struct virtio_input_event *stsbuf;
        unsigned long flags;
        unsigned int len;

        spin_lock_irqsave(&vi->lock, flags);
        while ((stsbuf = virtqueue_get_buf(vi->sts, &len)) != NULL)
                kfree(stsbuf);
        spin_unlock_irqrestore(&vi->lock, flags);
}

static int virtinput_status(struct input_dev *idev, unsigned int type,
                            unsigned int code, int value)
{
        struct virtio_input *vi = input_get_drvdata(idev);

        return virtinput_send_status(vi, type, code, value);
}

static u8 virtinput_cfg_select(struct virtio_input *vi,
                               u8 select, u8 subsel)
{
        u8 size;

        virtio_cwrite_le(vi->vdev, struct virtio_input_config, select, &select);
        virtio_cwrite_le(vi->vdev, struct virtio_input_config, subsel, &subsel);
        virtio_cread_le(vi->vdev, struct virtio_input_config, size, &size);
        return size;
}

static void virtinput_cfg_bits(struct virtio_input *vi, int select, int subsel,
                               unsigned long *bits, unsigned int bitcount)
{
        unsigned int bit;
        u8 *virtio_bits;
        u8 bytes;

        bytes = virtinput_cfg_select(vi, select, subsel);
        if (!bytes)
                return;
        if (bitcount > bytes * 8)
                bitcount = bytes * 8;

        /*
         * Bitmap in virtio config space is a simple stream of bytes,
         * with the first byte carrying bits 0-7, second bits 8-15 and
         * so on.
         */
        virtio_bits = kzalloc(bytes, GFP_KERNEL);
        if (!virtio_bits)
                return;
        virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config,
                                              u.bitmap),
                           virtio_bits, bytes);
        for (bit = 0; bit < bitcount; bit++) {
                if (virtio_bits[bit / 8] & (1 << (bit % 8)))
                        __set_bit(bit, bits);
        }
        kfree(virtio_bits);

        if (select == VIRTIO_INPUT_CFG_EV_BITS)
                __set_bit(subsel, vi->idev->evbit);
}

static void virtinput_cfg_abs(struct virtio_input *vi, int abs)
{
        u32 mi, ma, re, fu, fl;

        virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ABS_INFO, abs);
        virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.min, &mi);
        virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.max, &ma);
        virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.res, &re);
        virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.fuzz, &fu);
        virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.flat, &fl);
        input_set_abs_params(vi->idev, abs, mi, ma, fu, fl);
        input_abs_set_res(vi->idev, abs, re);
}

static int virtinput_init_vqs(struct virtio_input *vi)
{
        struct virtqueue_info vqs_info[] = {
                { "events", virtinput_recv_events },
                { "status", virtinput_recv_status },
        };
        struct virtqueue *vqs[2];
        int err;

        err = virtio_find_vqs(vi->vdev, 2, vqs, vqs_info, NULL);
        if (err)
                return err;
        vi->evt = vqs[0];
        vi->sts = vqs[1];

        return 0;
}

static void virtinput_fill_evt(struct virtio_input *vi)
{
        unsigned long flags;
        int i, size;

        spin_lock_irqsave(&vi->lock, flags);
        size = virtqueue_get_vring_size(vi->evt);
        if (size > ARRAY_SIZE(vi->evts))
                size = ARRAY_SIZE(vi->evts);
        for (i = 0; i < size; i++)
                virtinput_queue_evtbuf(vi, &vi->evts[i]);
        virtqueue_kick(vi->evt);
        spin_unlock_irqrestore(&vi->lock, flags);
}

static int virtinput_probe(struct virtio_device *vdev)
{
        struct virtio_input *vi;
        unsigned long flags;
        size_t size;
        int abs, err, nslots;

        if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
                return -ENODEV;

        vi = kzalloc_obj(*vi);
        if (!vi)
                return -ENOMEM;

        vdev->priv = vi;
        vi->vdev = vdev;
        spin_lock_init(&vi->lock);

        err = virtinput_init_vqs(vi);
        if (err)
                goto err_init_vq;

        vi->idev = input_allocate_device();
        if (!vi->idev) {
                err = -ENOMEM;
                goto err_input_alloc;
        }
        input_set_drvdata(vi->idev, vi);

        size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_NAME, 0);
        virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config,
                                              u.string),
                           vi->name, min(size, sizeof(vi->name)));
        size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_SERIAL, 0);
        virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config,
                                              u.string),
                           vi->serial, min(size, sizeof(vi->serial)));
        snprintf(vi->phys, sizeof(vi->phys),
                 "virtio%d/input0", vdev->index);
        vi->idev->name = vi->name;
        vi->idev->phys = vi->phys;
        vi->idev->uniq = vi->serial;

        size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_DEVIDS, 0);
        if (size >= sizeof(struct virtio_input_devids)) {
                virtio_cread_le(vi->vdev, struct virtio_input_config,
                                u.ids.bustype, &vi->idev->id.bustype);
                virtio_cread_le(vi->vdev, struct virtio_input_config,
                                u.ids.vendor, &vi->idev->id.vendor);
                virtio_cread_le(vi->vdev, struct virtio_input_config,
                                u.ids.product, &vi->idev->id.product);
                virtio_cread_le(vi->vdev, struct virtio_input_config,
                                u.ids.version, &vi->idev->id.version);
        } else {
                vi->idev->id.bustype = BUS_VIRTUAL;
        }

        virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_PROP_BITS, 0,
                           vi->idev->propbit, INPUT_PROP_CNT);
        size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_REP);
        if (size)
                __set_bit(EV_REP, vi->idev->evbit);

        vi->idev->dev.parent = &vdev->dev;
        vi->idev->event = virtinput_status;

        /* device -> kernel */
        virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_KEY,
                           vi->idev->keybit, KEY_CNT);
        virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_REL,
                           vi->idev->relbit, REL_CNT);
        virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_ABS,
                           vi->idev->absbit, ABS_CNT);
        virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_MSC,
                           vi->idev->mscbit, MSC_CNT);
        virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_SW,
                           vi->idev->swbit,  SW_CNT);

        /* kernel -> device */
        virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_LED,
                           vi->idev->ledbit, LED_CNT);
        virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_SND,
                           vi->idev->sndbit, SND_CNT);

        if (test_bit(EV_ABS, vi->idev->evbit)) {
                for (abs = 0; abs < ABS_CNT; abs++) {
                        if (!test_bit(abs, vi->idev->absbit))
                                continue;
                        virtinput_cfg_abs(vi, abs);
                }

                if (test_bit(ABS_MT_SLOT, vi->idev->absbit)) {
                        nslots = input_abs_get_max(vi->idev, ABS_MT_SLOT) + 1;
                        err = input_mt_init_slots(vi->idev, nslots, 0);
                        if (err)
                                goto err_mt_init_slots;
                }
        }

        virtio_device_ready(vdev);
        vi->ready = true;
        err = input_register_device(vi->idev);
        if (err)
                goto err_input_register;

        virtinput_fill_evt(vi);
        return 0;

err_input_register:
        spin_lock_irqsave(&vi->lock, flags);
        vi->ready = false;
        spin_unlock_irqrestore(&vi->lock, flags);
err_mt_init_slots:
        input_free_device(vi->idev);
err_input_alloc:
        vdev->config->del_vqs(vdev);
err_init_vq:
        kfree(vi);
        return err;
}

static void virtinput_remove(struct virtio_device *vdev)
{
        struct virtio_input *vi = vdev->priv;
        void *buf;
        unsigned long flags;

        spin_lock_irqsave(&vi->lock, flags);
        vi->ready = false;
        spin_unlock_irqrestore(&vi->lock, flags);

        input_unregister_device(vi->idev);
        virtio_reset_device(vdev);
        while ((buf = virtqueue_detach_unused_buf(vi->sts)) != NULL)
                kfree(buf);
        vdev->config->del_vqs(vdev);
        kfree(vi);
}

#ifdef CONFIG_PM_SLEEP
static int virtinput_freeze(struct virtio_device *vdev)
{
        struct virtio_input *vi = vdev->priv;
        unsigned long flags;
        void *buf;

        spin_lock_irqsave(&vi->lock, flags);
        vi->ready = false;
        spin_unlock_irqrestore(&vi->lock, flags);

        virtio_reset_device(vdev);
        while ((buf = virtqueue_detach_unused_buf(vi->sts)) != NULL)
                kfree(buf);
        vdev->config->del_vqs(vdev);
        return 0;
}

static int virtinput_restore(struct virtio_device *vdev)
{
        struct virtio_input *vi = vdev->priv;
        int err;

        err = virtinput_init_vqs(vi);
        if (err)
                return err;

        virtio_device_ready(vdev);
        vi->ready = true;
        virtinput_fill_evt(vi);
        return 0;
}
#endif

static unsigned int features[] = {
        /* none */
};
static const struct virtio_device_id id_table[] = {
        { VIRTIO_ID_INPUT, VIRTIO_DEV_ANY_ID },
        { 0 },
};

static struct virtio_driver virtio_input_driver = {
        .driver.name         = KBUILD_MODNAME,
        .feature_table       = features,
        .feature_table_size  = ARRAY_SIZE(features),
        .id_table            = id_table,
        .probe               = virtinput_probe,
        .remove              = virtinput_remove,
#ifdef CONFIG_PM_SLEEP
        .freeze              = virtinput_freeze,
        .restore             = virtinput_restore,
#endif
};

module_virtio_driver(virtio_input_driver);
MODULE_DEVICE_TABLE(virtio, id_table);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Virtio input device driver");
MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>");