// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Red Hat
 *
 * based in parts on udlfb.c:
 * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
 * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
 * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
 */

#include <linux/unaligned.h>

#include <drm/drm.h>
#include <drm/drm_print.h>
#include <drm/drm_probe_helper.h>

#include "udl_drv.h"

/* -BULK_SIZE as per usb-skeleton. Can we get full page and avoid overhead? */
#define BULK_SIZE 512

#define NR_USB_REQUEST_CHANNEL 0x12

#define MAX_TRANSFER (PAGE_SIZE*16 - BULK_SIZE)
#define WRITES_IN_FLIGHT (20)
#define MAX_VENDOR_DESCRIPTOR_SIZE 256

#define UDL_SKU_PIXEL_LIMIT_DEFAULT     2080000

static struct urb *udl_get_urb_locked(struct udl_device *udl, long timeout);

/*
 * Try to make sense of whatever we parse. Therefore return @end on
 * errors, but don't fail hard.
 */
static const u8 *udl_parse_key_value_pair(struct udl_device *udl, const u8 *pos, const u8 *end)
{
        u16 key;
        u8 len;

        /* read key */
        if (pos >= end - 2)
                return end;
        key = get_unaligned_le16(pos);
        pos += 2;

        /* read value length */
        if (pos >= end - 1)
                return end;
        len = *pos++;

        /* read value */
        if (pos >= end - len)
                return end;
        switch (key) {
        case 0x0200: { /* maximum number of pixels */
                unsigned int sku_pixel_limit;

                if (len < sizeof(__le32))
                        break;
                sku_pixel_limit = get_unaligned_le32(pos);
                if (sku_pixel_limit >= 16 * UDL_SKU_PIXEL_LIMIT_DEFAULT)
                        break; /* almost 100 MiB, so probably bogus */
                udl->sku_pixel_limit = sku_pixel_limit;
                break;
        }
        default:
                break;
        }
        pos += len;

        return pos;
}

static int udl_parse_vendor_descriptor(struct udl_device *udl)
{
        struct drm_device *dev = &udl->drm;
        struct usb_device *udev = udl_to_usb_device(udl);
        bool detected = false;
        void *buf;
        int ret;
        unsigned int len;
        const u8 *desc;
        const u8 *desc_end;

        buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        ret = usb_get_descriptor(udev, 0x5f, /* vendor specific */
                                 0, buf, MAX_VENDOR_DESCRIPTOR_SIZE);
        if (ret < 0)
                goto out;
        len = ret;

        if (len < 5)
                goto out;

        desc = buf;
        desc_end = desc + len;

        if ((desc[0] != len) ||    /* descriptor length */
            (desc[1] != 0x5f) ||   /* vendor descriptor type */
            (desc[2] != 0x01) ||   /* version (2 bytes) */
            (desc[3] != 0x00) ||
            (desc[4] != len - 2))  /* length after type */
                goto out;
        desc += 5;

        detected = true;

        while (desc < desc_end)
                desc = udl_parse_key_value_pair(udl, desc, desc_end);

out:
        if (!detected)
                drm_warn(dev, "Unrecognized vendor firmware descriptor\n");
        kfree(buf);

        return 0;
}

/*
 * Need to ensure a channel is selected before submitting URBs
 */
int udl_select_std_channel(struct udl_device *udl)
{
        static const u8 set_def_chn[] = {0x57, 0xCD, 0xDC, 0xA7,
                                         0x1C, 0x88, 0x5E, 0x15,
                                         0x60, 0xFE, 0xC6, 0x97,
                                         0x16, 0x3D, 0x47, 0xF2};

        void *sendbuf;
        int ret;
        struct usb_device *udev = udl_to_usb_device(udl);

        sendbuf = kmemdup(set_def_chn, sizeof(set_def_chn), GFP_KERNEL);
        if (!sendbuf)
                return -ENOMEM;

        ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                              NR_USB_REQUEST_CHANNEL,
                              (USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
                              sendbuf, sizeof(set_def_chn),
                              USB_CTRL_SET_TIMEOUT);
        kfree(sendbuf);
        return ret < 0 ? ret : 0;
}

void udl_urb_completion(struct urb *urb)
{
        struct urb_node *unode = urb->context;
        struct udl_device *udl = unode->dev;
        unsigned long flags;

        /* sync/async unlink faults aren't errors */
        if (urb->status) {
                if (!(urb->status == -ENOENT ||
                    urb->status == -ECONNRESET ||
                    urb->status == -EPROTO ||
                    urb->status == -ESHUTDOWN)) {
                        DRM_ERROR("%s - nonzero write bulk status received: %d\n",
                                __func__, urb->status);
                }
        }

        urb->transfer_buffer_length = udl->urbs.size; /* reset to actual */

        spin_lock_irqsave(&udl->urbs.lock, flags);
        list_add_tail(&unode->entry, &udl->urbs.list);
        udl->urbs.available++;
        spin_unlock_irqrestore(&udl->urbs.lock, flags);

        wake_up(&udl->urbs.sleep);
}

static void udl_free_urb_list(struct udl_device *udl)
{
        struct urb_node *unode;
        struct urb *urb;

        DRM_DEBUG("Waiting for completes and freeing all render urbs\n");

        /* keep waiting and freeing, until we've got 'em all */
        while (udl->urbs.count) {
                spin_lock_irq(&udl->urbs.lock);
                urb = udl_get_urb_locked(udl, MAX_SCHEDULE_TIMEOUT);
                udl->urbs.count--;
                spin_unlock_irq(&udl->urbs.lock);
                if (WARN_ON(!urb))
                        break;
                unode = urb->context;
                /* Free each separately allocated piece */
                usb_free_coherent(urb->dev, udl->urbs.size,
                                  urb->transfer_buffer, urb->transfer_dma);
                usb_free_urb(urb);
                kfree(unode);
        }

        wake_up_all(&udl->urbs.sleep);
}

static int udl_alloc_urb_list(struct udl_device *udl, int count, size_t size)
{
        struct urb *urb;
        struct urb_node *unode;
        char *buf;
        size_t wanted_size = count * size;
        struct usb_device *udev = udl_to_usb_device(udl);

        spin_lock_init(&udl->urbs.lock);
        INIT_LIST_HEAD(&udl->urbs.list);
        init_waitqueue_head(&udl->urbs.sleep);
        udl->urbs.count = 0;
        udl->urbs.available = 0;

retry:
        udl->urbs.size = size;

        while (udl->urbs.count * size < wanted_size) {
                unode = kzalloc_obj(struct urb_node);
                if (!unode)
                        break;
                unode->dev = udl;

                urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!urb) {
                        kfree(unode);
                        break;
                }
                unode->urb = urb;

                buf = usb_alloc_coherent(udev, size, GFP_KERNEL,
                                         &urb->transfer_dma);
                if (!buf) {
                        kfree(unode);
                        usb_free_urb(urb);
                        if (size > PAGE_SIZE) {
                                size /= 2;
                                udl_free_urb_list(udl);
                                goto retry;
                        }
                        break;
                }

                /* urb->transfer_buffer_length set to actual before submit */
                usb_fill_bulk_urb(urb, udev, usb_sndbulkpipe(udev, 1),
                                  buf, size, udl_urb_completion, unode);
                urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

                list_add_tail(&unode->entry, &udl->urbs.list);

                udl->urbs.count++;
                udl->urbs.available++;
        }

        DRM_DEBUG("allocated %d %d byte urbs\n", udl->urbs.count, (int) size);

        return udl->urbs.count;
}

static struct urb *udl_get_urb_locked(struct udl_device *udl, long timeout)
{
        struct urb_node *unode;

        assert_spin_locked(&udl->urbs.lock);

        /* Wait for an in-flight buffer to complete and get re-queued */
        if (!wait_event_lock_irq_timeout(udl->urbs.sleep,
                                         !udl->urbs.count ||
                                         !list_empty(&udl->urbs.list),
                                         udl->urbs.lock, timeout)) {
                DRM_INFO("wait for urb interrupted: available: %d\n",
                         udl->urbs.available);
                return NULL;
        }

        if (!udl->urbs.count)
                return NULL;

        unode = list_first_entry(&udl->urbs.list, struct urb_node, entry);
        list_del_init(&unode->entry);
        udl->urbs.available--;

        return unode->urb;
}

#define GET_URB_TIMEOUT HZ
struct urb *udl_get_urb(struct udl_device *udl)
{
        struct urb *urb;

        spin_lock_irq(&udl->urbs.lock);
        urb = udl_get_urb_locked(udl, GET_URB_TIMEOUT);
        spin_unlock_irq(&udl->urbs.lock);
        return urb;
}

int udl_submit_urb(struct udl_device *udl, struct urb *urb, size_t len)
{
        int ret;

        if (WARN_ON(len > udl->urbs.size)) {
                ret = -EINVAL;
                goto error;
        }
        urb->transfer_buffer_length = len; /* set to actual payload len */
        ret = usb_submit_urb(urb, GFP_ATOMIC);
 error:
        if (ret) {
                udl_urb_completion(urb); /* because no one else will */
                DRM_ERROR("usb_submit_urb error %x\n", ret);
        }
        return ret;
}

/* wait until all pending URBs have been processed */
void udl_sync_pending_urbs(struct udl_device *udl)
{
        struct drm_device *dev = &udl->drm;

        spin_lock_irq(&udl->urbs.lock);
        /* 2 seconds as a sane timeout */
        if (!wait_event_lock_irq_timeout(udl->urbs.sleep,
                                         udl->urbs.available == udl->urbs.count,
                                         udl->urbs.lock,
                                         msecs_to_jiffies(2000)))
                drm_err(dev, "Timeout for syncing pending URBs\n");
        spin_unlock_irq(&udl->urbs.lock);
}

int udl_init(struct udl_device *udl)
{
        struct drm_device *dev = &udl->drm;
        int ret = -ENOMEM;
        struct device *dma_dev;

        DRM_DEBUG("\n");

        dma_dev = usb_intf_get_dma_device(to_usb_interface(dev->dev));
        if (dma_dev) {
                drm_dev_set_dma_dev(dev, dma_dev);
                put_device(dma_dev);
        } else {
                drm_warn(dev, "buffer sharing not supported"); /* not an error */
        }

        /*
         * Not all devices provide vendor descriptors with device
         * information. Initialize to default values of real-world
         * devices. It is just enough memory for FullHD.
         */
        udl->sku_pixel_limit = UDL_SKU_PIXEL_LIMIT_DEFAULT;

        ret = udl_parse_vendor_descriptor(udl);
        if (ret)
                goto err;

        if (udl_select_std_channel(udl))
                DRM_ERROR("Selecting channel failed\n");

        if (!udl_alloc_urb_list(udl, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
                DRM_ERROR("udl_alloc_urb_list failed\n");
                ret = -ENOMEM;
                goto err;
        }

        DRM_DEBUG("\n");
        ret = udl_modeset_init(udl);
        if (ret)
                goto err;

        return 0;

err:
        if (udl->urbs.count)
                udl_free_urb_list(udl);
        DRM_ERROR("%d\n", ret);
        return ret;
}

int udl_drop_usb(struct udl_device *udl)
{
        udl_free_urb_list(udl);

        return 0;
}