// 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/bitfield.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_damage_helper.h>
#include <drm/drm_drv.h>
#include <drm/drm_edid.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_gem_shmem_helper.h>
#include <drm/drm_modeset_helper_vtables.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_vblank.h>

#include "udl_drv.h"
#include "udl_edid.h"
#include "udl_proto.h"

/*
 * All DisplayLink bulk operations start with 0xaf (UDL_MSG_BULK), followed by
 * a specific command code. All operations are written to a command buffer, which
 * the driver sends to the device.
 */
static char *udl_set_register(char *buf, u8 reg, u8 val)
{
        *buf++ = UDL_MSG_BULK;
        *buf++ = UDL_CMD_WRITEREG;
        *buf++ = reg;
        *buf++ = val;

        return buf;
}

static char *udl_vidreg_lock(char *buf)
{
        return udl_set_register(buf, UDL_REG_VIDREG, UDL_VIDREG_LOCK);
}

static char *udl_vidreg_unlock(char *buf)
{
        return udl_set_register(buf, UDL_REG_VIDREG, UDL_VIDREG_UNLOCK);
}

static char *udl_set_blank_mode(char *buf, u8 mode)
{
        return udl_set_register(buf, UDL_REG_BLANKMODE, mode);
}

static char *udl_set_color_depth(char *buf, u8 selection)
{
        return udl_set_register(buf, UDL_REG_COLORDEPTH, selection);
}

static char *udl_set_base16bpp(char *buf, u32 base)
{
        /* the base pointer is 24 bits wide, 0x20 is hi byte. */
        u8 reg20 = FIELD_GET(UDL_BASE_ADDR2_MASK, base);
        u8 reg21 = FIELD_GET(UDL_BASE_ADDR1_MASK, base);
        u8 reg22 = FIELD_GET(UDL_BASE_ADDR0_MASK, base);

        buf = udl_set_register(buf, UDL_REG_BASE16BPP_ADDR2, reg20);
        buf = udl_set_register(buf, UDL_REG_BASE16BPP_ADDR1, reg21);
        buf = udl_set_register(buf, UDL_REG_BASE16BPP_ADDR0, reg22);

        return buf;
}

/*
 * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
 * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
 */
static char *udl_set_base8bpp(char *buf, u32 base)
{
        /* the base pointer is 24 bits wide, 0x26 is hi byte. */
        u8 reg26 = FIELD_GET(UDL_BASE_ADDR2_MASK, base);
        u8 reg27 = FIELD_GET(UDL_BASE_ADDR1_MASK, base);
        u8 reg28 = FIELD_GET(UDL_BASE_ADDR0_MASK, base);

        buf = udl_set_register(buf, UDL_REG_BASE8BPP_ADDR2, reg26);
        buf = udl_set_register(buf, UDL_REG_BASE8BPP_ADDR1, reg27);
        buf = udl_set_register(buf, UDL_REG_BASE8BPP_ADDR0, reg28);

        return buf;
}

static char *udl_set_register_16(char *wrptr, u8 reg, u16 value)
{
        wrptr = udl_set_register(wrptr, reg, value >> 8);
        return udl_set_register(wrptr, reg+1, value);
}

/*
 * This is kind of weird because the controller takes some
 * register values in a different byte order than other registers.
 */
static char *udl_set_register_16be(char *wrptr, u8 reg, u16 value)
{
        wrptr = udl_set_register(wrptr, reg, value);
        return udl_set_register(wrptr, reg+1, value >> 8);
}

/*
 * LFSR is linear feedback shift register. The reason we have this is
 * because the display controller needs to minimize the clock depth of
 * various counters used in the display path. So this code reverses the
 * provided value into the lfsr16 value by counting backwards to get
 * the value that needs to be set in the hardware comparator to get the
 * same actual count. This makes sense once you read above a couple of
 * times and think about it from a hardware perspective.
 */
static u16 udl_lfsr16(u16 actual_count)
{
        u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */

        while (actual_count--) {
                lv =     ((lv << 1) |
                        (((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
                        & 0xFFFF;
        }

        return (u16) lv;
}

/*
 * This does LFSR conversion on the value that is to be written.
 * See LFSR explanation above for more detail.
 */
static char *udl_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
{
        return udl_set_register_16(wrptr, reg, udl_lfsr16(value));
}

/*
 * Takes a DRM display mode and converts it into the DisplayLink
 * equivalent register commands.
 */
static char *udl_set_display_mode(char *buf, struct drm_display_mode *mode)
{
        u16 reg01 = mode->crtc_htotal - mode->crtc_hsync_start;
        u16 reg03 = reg01 + mode->crtc_hdisplay;
        u16 reg05 = mode->crtc_vtotal - mode->crtc_vsync_start;
        u16 reg07 = reg05 + mode->crtc_vdisplay;
        u16 reg09 = mode->crtc_htotal - 1;
        u16 reg0b = 1; /* libdlo hardcodes hsync start to 1 */
        u16 reg0d = mode->crtc_hsync_end - mode->crtc_hsync_start + 1;
        u16 reg0f = mode->hdisplay;
        u16 reg11 = mode->crtc_vtotal;
        u16 reg13 = 0; /* libdlo hardcodes vsync start to 0 */
        u16 reg15 = mode->crtc_vsync_end - mode->crtc_vsync_start;
        u16 reg17 = mode->crtc_vdisplay;
        u16 reg1b = mode->clock / 5;

        buf = udl_set_register_lfsr16(buf, UDL_REG_XDISPLAYSTART, reg01);
        buf = udl_set_register_lfsr16(buf, UDL_REG_XDISPLAYEND, reg03);
        buf = udl_set_register_lfsr16(buf, UDL_REG_YDISPLAYSTART, reg05);
        buf = udl_set_register_lfsr16(buf, UDL_REG_YDISPLAYEND, reg07);
        buf = udl_set_register_lfsr16(buf, UDL_REG_XENDCOUNT, reg09);
        buf = udl_set_register_lfsr16(buf, UDL_REG_HSYNCSTART, reg0b);
        buf = udl_set_register_lfsr16(buf, UDL_REG_HSYNCEND, reg0d);
        buf = udl_set_register_16(buf, UDL_REG_HPIXELS, reg0f);
        buf = udl_set_register_lfsr16(buf, UDL_REG_YENDCOUNT, reg11);
        buf = udl_set_register_lfsr16(buf, UDL_REG_VSYNCSTART, reg13);
        buf = udl_set_register_lfsr16(buf, UDL_REG_VSYNCEND, reg15);
        buf = udl_set_register_16(buf, UDL_REG_VPIXELS, reg17);
        buf = udl_set_register_16be(buf, UDL_REG_PIXELCLOCK5KHZ, reg1b);

        return buf;
}

static char *udl_dummy_render(char *wrptr)
{
        *wrptr++ = UDL_MSG_BULK;
        *wrptr++ = UDL_CMD_WRITECOPY16;
        *wrptr++ = 0x00; /* from addr */
        *wrptr++ = 0x00;
        *wrptr++ = 0x00;
        *wrptr++ = 0x01; /* one pixel */
        *wrptr++ = 0x00; /* to address */
        *wrptr++ = 0x00;
        *wrptr++ = 0x00;
        return wrptr;
}

static long udl_log_cpp(unsigned int cpp)
{
        if (WARN_ON(!is_power_of_2(cpp)))
                return -EINVAL;
        return __ffs(cpp);
}

static int udl_handle_damage(struct drm_framebuffer *fb,
                             const struct iosys_map *map,
                             const struct drm_rect *clip)
{
        struct drm_device *dev = fb->dev;
        struct udl_device *udl = to_udl(dev);
        void *vaddr = map->vaddr; /* TODO: Use mapping abstraction properly */
        int i, ret;
        char *cmd;
        struct urb *urb;
        int log_bpp;

        ret = udl_log_cpp(fb->format->cpp[0]);
        if (ret < 0)
                return ret;
        log_bpp = ret;

        urb = udl_get_urb(udl);
        if (!urb)
                return -ENOMEM;
        cmd = urb->transfer_buffer;

        for (i = clip->y1; i < clip->y2; i++) {
                const int line_offset = fb->pitches[0] * i;
                const int byte_offset = line_offset + (clip->x1 << log_bpp);
                const int dev_byte_offset = (fb->width * i + clip->x1) << log_bpp;
                const int byte_width = drm_rect_width(clip) << log_bpp;
                ret = udl_render_hline(udl, log_bpp, &urb, (char *)vaddr,
                                       &cmd, byte_offset, dev_byte_offset,
                                       byte_width);
                if (ret)
                        return ret;
        }

        if (cmd > (char *)urb->transfer_buffer) {
                /* Send partial buffer remaining before exiting */
                int len;
                if (cmd < (char *)urb->transfer_buffer + urb->transfer_buffer_length)
                        *cmd++ = UDL_MSG_BULK;
                len = cmd - (char *)urb->transfer_buffer;
                ret = udl_submit_urb(udl, urb, len);
        } else {
                udl_urb_completion(urb);
        }

        return 0;
}

/*
 * Primary plane
 */

static const uint32_t udl_primary_plane_formats[] = {
        DRM_FORMAT_RGB565,
        DRM_FORMAT_XRGB8888,
};

static const uint64_t udl_primary_plane_fmtmods[] = {
        DRM_FORMAT_MOD_LINEAR,
        DRM_FORMAT_MOD_INVALID
};

static int udl_primary_plane_helper_atomic_check(struct drm_plane *plane,
                                                 struct drm_atomic_state *state)
{
        struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state, plane);
        struct drm_crtc *new_crtc = new_plane_state->crtc;
        struct drm_crtc_state *new_crtc_state = NULL;

        if (new_crtc)
                new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);

        return drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state,
                                                   DRM_PLANE_NO_SCALING,
                                                   DRM_PLANE_NO_SCALING,
                                                   false, false);
}

static void udl_primary_plane_helper_atomic_update(struct drm_plane *plane,
                                                   struct drm_atomic_state *state)
{
        struct drm_device *dev = plane->dev;
        struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
        struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
        struct drm_framebuffer *fb = plane_state->fb;
        struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
        struct drm_atomic_helper_damage_iter iter;
        struct drm_rect damage;
        int ret, idx;

        if (!fb)
                return; /* no framebuffer; plane is disabled */

        ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
        if (ret)
                return;

        if (!drm_dev_enter(dev, &idx))
                goto out_drm_gem_fb_end_cpu_access;

        drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
        drm_atomic_for_each_plane_damage(&iter, &damage) {
                udl_handle_damage(fb, &shadow_plane_state->data[0], &damage);
        }

        drm_dev_exit(idx);

out_drm_gem_fb_end_cpu_access:
        drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
}

static const struct drm_plane_helper_funcs udl_primary_plane_helper_funcs = {
        DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
        .atomic_check = udl_primary_plane_helper_atomic_check,
        .atomic_update = udl_primary_plane_helper_atomic_update,
};

static const struct drm_plane_funcs udl_primary_plane_funcs = {
        .update_plane = drm_atomic_helper_update_plane,
        .disable_plane = drm_atomic_helper_disable_plane,
        .destroy = drm_plane_cleanup,
        DRM_GEM_SHADOW_PLANE_FUNCS,
};

/*
 * CRTC
 */

static void udl_crtc_helper_atomic_enable(struct drm_crtc *crtc, struct drm_atomic_state *state)
{
        struct drm_device *dev = crtc->dev;
        struct udl_device *udl = to_udl(dev);
        struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
        struct drm_display_mode *mode = &crtc_state->mode;
        struct urb *urb;
        char *buf;
        int idx;

        if (!drm_dev_enter(dev, &idx))
                return;

        urb = udl_get_urb(udl);
        if (!urb)
                goto out;

        buf = (char *)urb->transfer_buffer;
        buf = udl_vidreg_lock(buf);
        buf = udl_set_color_depth(buf, UDL_COLORDEPTH_16BPP);
        /* set base for 16bpp segment to 0 */
        buf = udl_set_base16bpp(buf, 0);
        /* set base for 8bpp segment to end of fb */
        buf = udl_set_base8bpp(buf, 2 * mode->vdisplay * mode->hdisplay);
        buf = udl_set_display_mode(buf, mode);
        buf = udl_set_blank_mode(buf, UDL_BLANKMODE_ON);
        buf = udl_vidreg_unlock(buf);
        buf = udl_dummy_render(buf);

        udl_submit_urb(udl, urb, buf - (char *)urb->transfer_buffer);

out:
        drm_dev_exit(idx);
}

static void udl_crtc_helper_atomic_disable(struct drm_crtc *crtc, struct drm_atomic_state *state)
{
        struct drm_device *dev = crtc->dev;
        struct udl_device *udl = to_udl(dev);
        struct urb *urb;
        char *buf;
        int idx;

        if (!drm_dev_enter(dev, &idx))
                return;

        urb = udl_get_urb(udl);
        if (!urb)
                goto out;

        buf = (char *)urb->transfer_buffer;
        buf = udl_vidreg_lock(buf);
        buf = udl_set_blank_mode(buf, UDL_BLANKMODE_POWERDOWN);
        buf = udl_vidreg_unlock(buf);
        buf = udl_dummy_render(buf);

        udl_submit_urb(udl, urb, buf - (char *)urb->transfer_buffer);

out:
        drm_dev_exit(idx);
}

static const struct drm_crtc_helper_funcs udl_crtc_helper_funcs = {
        .atomic_check = drm_crtc_helper_atomic_check,
        .atomic_enable = udl_crtc_helper_atomic_enable,
        .atomic_disable = udl_crtc_helper_atomic_disable,
};

static const struct drm_crtc_funcs udl_crtc_funcs = {
        .reset = drm_atomic_helper_crtc_reset,
        .destroy = drm_crtc_cleanup,
        .set_config = drm_atomic_helper_set_config,
        .page_flip = drm_atomic_helper_page_flip,
        .atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
};

/*
 * Encoder
 */

static const struct drm_encoder_funcs udl_encoder_funcs = {
        .destroy = drm_encoder_cleanup,
};

/*
 * Connector
 */

static int udl_connector_helper_get_modes(struct drm_connector *connector)
{
        const struct drm_edid *drm_edid;
        int count;

        drm_edid = udl_edid_read(connector);
        drm_edid_connector_update(connector, drm_edid);
        count = drm_edid_connector_add_modes(connector);
        drm_edid_free(drm_edid);

        return count;
}

static int udl_connector_helper_detect_ctx(struct drm_connector *connector,
                                           struct drm_modeset_acquire_ctx *ctx,
                                           bool force)
{
        struct udl_device *udl = to_udl(connector->dev);

        if (udl_probe_edid(udl))
                return connector_status_connected;

        return connector_status_disconnected;
}

static const struct drm_connector_helper_funcs udl_connector_helper_funcs = {
        .get_modes = udl_connector_helper_get_modes,
        .detect_ctx = udl_connector_helper_detect_ctx,
};

static const struct drm_connector_funcs udl_connector_funcs = {
        .reset = drm_atomic_helper_connector_reset,
        .fill_modes = drm_helper_probe_single_connector_modes,
        .destroy = drm_connector_cleanup,
        .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
};

/*
 * Modesetting
 */

static enum drm_mode_status udl_mode_config_mode_valid(struct drm_device *dev,
                                                       const struct drm_display_mode *mode)
{
        struct udl_device *udl = to_udl(dev);

        if (udl->sku_pixel_limit) {
                if (mode->vdisplay * mode->hdisplay > udl->sku_pixel_limit)
                        return MODE_MEM;
        }

        return MODE_OK;
}

static const struct drm_mode_config_funcs udl_mode_config_funcs = {
        .fb_create = drm_gem_fb_create_with_dirty,
        .mode_valid = udl_mode_config_mode_valid,
        .atomic_check  = drm_atomic_helper_check,
        .atomic_commit = drm_atomic_helper_commit,
};

int udl_modeset_init(struct udl_device *udl)
{
        struct drm_device *dev = &udl->drm;
        struct drm_plane *primary_plane;
        struct drm_crtc *crtc;
        struct drm_encoder *encoder;
        struct drm_connector *connector;
        int ret;

        ret = drmm_mode_config_init(dev);
        if (ret)
                return ret;

        dev->mode_config.min_width = 640;
        dev->mode_config.min_height = 480;
        dev->mode_config.max_width = 2048;
        dev->mode_config.max_height = 2048;
        dev->mode_config.preferred_depth = 16;
        dev->mode_config.funcs = &udl_mode_config_funcs;

        primary_plane = &udl->primary_plane;
        ret = drm_universal_plane_init(dev, primary_plane, 0,
                                       &udl_primary_plane_funcs,
                                       udl_primary_plane_formats,
                                       ARRAY_SIZE(udl_primary_plane_formats),
                                       udl_primary_plane_fmtmods,
                                       DRM_PLANE_TYPE_PRIMARY, NULL);
        if (ret)
                return ret;
        drm_plane_helper_add(primary_plane, &udl_primary_plane_helper_funcs);
        drm_plane_enable_fb_damage_clips(primary_plane);

        crtc = &udl->crtc;
        ret = drm_crtc_init_with_planes(dev, crtc, primary_plane, NULL,
                                        &udl_crtc_funcs, NULL);
        if (ret)
                return ret;
        drm_crtc_helper_add(crtc, &udl_crtc_helper_funcs);

        encoder = &udl->encoder;
        ret = drm_encoder_init(dev, encoder, &udl_encoder_funcs, DRM_MODE_ENCODER_DAC, NULL);
        if (ret)
                return ret;
        encoder->possible_crtcs = drm_crtc_mask(crtc);

        connector = &udl->connector;
        ret = drm_connector_init(dev, connector, &udl_connector_funcs, DRM_MODE_CONNECTOR_VGA);
        if (ret)
                return ret;
        drm_connector_helper_add(connector, &udl_connector_helper_funcs);

        connector->polled = DRM_CONNECTOR_POLL_CONNECT |
                            DRM_CONNECTOR_POLL_DISCONNECT;

        ret = drm_connector_attach_encoder(connector, encoder);
        if (ret)
                return ret;

        drm_mode_config_reset(dev);
        drmm_kms_helper_poll_init(dev);

        return 0;
}