// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * drm kms/fb dma helper functions
 *
 * Copyright (C) 2012 Analog Devices Inc.
 *   Author: Lars-Peter Clausen <lars@metafoo.de>
 *
 * Based on udl_fbdev.c
 *  Copyright (C) 2012 Red Hat
 */

#include <drm/drm_damage_helper.h>
#include <drm/drm_fb_dma_helper.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem_dma_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_panic.h>
#include <drm/drm_plane.h>

#include <linux/dma-mapping.h>
#include <linux/export.h>
#include <linux/module.h>

/**
 * DOC: framebuffer dma helper functions
 *
 * Provides helper functions for creating a DMA-contiguous framebuffer.
 *
 * Depending on the platform, the buffers may be physically non-contiguous and
 * mapped through an IOMMU or a similar mechanism, or allocated from
 * physically-contiguous memory (using, for instance, CMA or a pool of memory
 * reserved at early boot). This is handled behind the scenes by the DMA mapping
 * API.
 *
 * drm_gem_fb_create() is used in the &drm_mode_config_funcs.fb_create
 * callback function to create a DMA-contiguous framebuffer.
 */

/**
 * drm_fb_dma_get_gem_obj() - Get DMA GEM object for framebuffer
 * @fb: The framebuffer
 * @plane: Which plane
 *
 * Return the DMA GEM object for given framebuffer.
 *
 * This function will usually be called from the CRTC callback functions.
 */
struct drm_gem_dma_object *drm_fb_dma_get_gem_obj(struct drm_framebuffer *fb,
                                                  unsigned int plane)
{
        struct drm_gem_object *gem;

        gem = drm_gem_fb_get_obj(fb, plane);
        if (!gem)
                return NULL;

        return to_drm_gem_dma_obj(gem);
}
EXPORT_SYMBOL_GPL(drm_fb_dma_get_gem_obj);

/**
 * drm_fb_dma_get_gem_addr() - Get DMA (bus) address for framebuffer, for pixel
 * formats where values are grouped in blocks this will get you the beginning of
 * the block
 * @fb: The framebuffer
 * @state: Which state of drm plane
 * @plane: Which plane
 * Return the DMA GEM address for given framebuffer.
 *
 * This function will usually be called from the PLANE callback functions.
 */
dma_addr_t drm_fb_dma_get_gem_addr(struct drm_framebuffer *fb,
                                   struct drm_plane_state *state,
                                   unsigned int plane)
{
        struct drm_gem_dma_object *obj;
        dma_addr_t dma_addr;
        u8 h_div = 1, v_div = 1;
        u32 block_w = drm_format_info_block_width(fb->format, plane);
        u32 block_h = drm_format_info_block_height(fb->format, plane);
        u32 block_size = fb->format->char_per_block[plane];
        u32 sample_x;
        u32 sample_y;
        u32 block_start_y;
        u32 num_hblocks;

        obj = drm_fb_dma_get_gem_obj(fb, plane);
        if (!obj)
                return 0;

        dma_addr = obj->dma_addr + fb->offsets[plane];

        if (plane > 0) {
                h_div = fb->format->hsub;
                v_div = fb->format->vsub;
        }

        sample_x = (state->src_x >> 16) / h_div;
        sample_y = (state->src_y >> 16) / v_div;
        block_start_y = (sample_y / block_h) * block_h;
        num_hblocks = sample_x / block_w;

        dma_addr += fb->pitches[plane] * block_start_y;
        dma_addr += block_size * num_hblocks;

        return dma_addr;
}
EXPORT_SYMBOL_GPL(drm_fb_dma_get_gem_addr);

/**
 * drm_fb_dma_sync_non_coherent - Sync GEM object to non-coherent backing
 *      memory
 * @drm: DRM device
 * @old_state: Old plane state
 * @state: New plane state
 *
 * This function can be used by drivers that use damage clips and have
 * DMA GEM objects backed by non-coherent memory. Calling this function
 * in a plane's .atomic_update ensures that all the data in the backing
 * memory have been written to RAM.
 */
void drm_fb_dma_sync_non_coherent(struct drm_device *drm,
                                  struct drm_plane_state *old_state,
                                  struct drm_plane_state *state)
{
        const struct drm_format_info *finfo = state->fb->format;
        struct drm_atomic_helper_damage_iter iter;
        const struct drm_gem_dma_object *dma_obj;
        unsigned int offset, i;
        struct drm_rect clip;
        dma_addr_t daddr;
        size_t nb_bytes;

        for (i = 0; i < finfo->num_planes; i++) {
                dma_obj = drm_fb_dma_get_gem_obj(state->fb, i);
                if (!dma_obj->map_noncoherent)
                        continue;

                daddr = drm_fb_dma_get_gem_addr(state->fb, state, i);
                drm_atomic_helper_damage_iter_init(&iter, old_state, state);

                drm_atomic_for_each_plane_damage(&iter, &clip) {
                        /* Ignore x1/x2 values, invalidate complete lines */
                        offset = clip.y1 * state->fb->pitches[i];

                        nb_bytes = (clip.y2 - clip.y1) * state->fb->pitches[i];
                        dma_sync_single_for_device(drm->dev, daddr + offset,
                                                   nb_bytes, DMA_TO_DEVICE);
                }
        }
}
EXPORT_SYMBOL_GPL(drm_fb_dma_sync_non_coherent);

/**
 * drm_fb_dma_get_scanout_buffer - Provide a scanout buffer in case of panic
 * @plane: DRM primary plane
 * @sb: scanout buffer for the panic handler
 * Returns: 0 or negative error code
 *
 * Generic get_scanout_buffer() implementation, for drivers that uses the
 * drm_fb_dma_helper. It won't call vmap in the panic context, so the driver
 * should make sure the primary plane is vmapped, otherwise the panic screen
 * won't get displayed.
 */
int drm_fb_dma_get_scanout_buffer(struct drm_plane *plane,
                                  struct drm_scanout_buffer *sb)
{
        struct drm_gem_dma_object *dma_obj;
        struct drm_framebuffer *fb;

        if (!plane->state || !plane->state->fb)
                return -EINVAL;

        fb = plane->state->fb;
        /* Only support linear modifier */
        if (fb->modifier != DRM_FORMAT_MOD_LINEAR)
                return -ENODEV;

        dma_obj = drm_fb_dma_get_gem_obj(fb, 0);

        /* Buffer should be accessible from the CPU */
        if (drm_gem_is_imported(&dma_obj->base))
                return -ENODEV;

        /* Buffer should be already mapped to CPU */
        if (!dma_obj->vaddr)
                return -ENODEV;

        iosys_map_set_vaddr(&sb->map[0], dma_obj->vaddr);
        sb->format = fb->format;
        sb->height = fb->height;
        sb->width = fb->width;
        sb->pitch[0] = fb->pitches[0];
        return 0;
}
EXPORT_SYMBOL(drm_fb_dma_get_scanout_buffer);