// SPDX-License-Identifier: GPL-2.0-only

#include <linux/export.h>
#include <linux/limits.h>
#include <linux/math64.h>
#include <linux/minmax.h>
#include <linux/screen_info.h>

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

#include "drm_sysfb_helper.h"

static s64 drm_sysfb_get_validated_size0(struct drm_device *dev, const char *name,
                                         u64 value, u64 max)
{
        if (!value) {
                drm_warn(dev, "%s of 0 not allowed\n", name);
                return -EINVAL;
        } else if (value > min(max, S64_MAX)) {
                drm_warn(dev, "%s of %llu exceeds maximum of %llu\n", name, value, max);
                return -EINVAL;
        }
        return value;
}

int drm_sysfb_get_width_si(struct drm_device *dev, const struct screen_info *si)
{
        return drm_sysfb_get_validated_int0(dev, "width", si->lfb_width, U16_MAX);
}
EXPORT_SYMBOL(drm_sysfb_get_width_si);

int drm_sysfb_get_height_si(struct drm_device *dev, const struct screen_info *si)
{
        return drm_sysfb_get_validated_int0(dev, "height", si->lfb_height, U16_MAX);
}
EXPORT_SYMBOL(drm_sysfb_get_height_si);

struct resource *drm_sysfb_get_memory_si(struct drm_device *dev,
                                         const struct screen_info *si,
                                         struct resource *res)
{
        ssize_t num;

        num = screen_info_resources(si, res, 1);
        if (!num) {
                drm_warn(dev, "memory resource not found\n");
                return NULL;
        }

        return res;
}
EXPORT_SYMBOL(drm_sysfb_get_memory_si);

int drm_sysfb_get_stride_si(struct drm_device *dev, const struct screen_info *si,
                            const struct drm_format_info *format,
                            unsigned int width, unsigned int height, u64 size)
{
        u64 lfb_linelength = si->lfb_linelength;
        s64 stride;

        if (!lfb_linelength)
                lfb_linelength = drm_format_info_min_pitch(format, 0, width);

        stride = drm_sysfb_get_validated_size0(dev, "stride", lfb_linelength,
                                               div64_u64(size, height));
        if (stride < INT_MIN || stride > INT_MAX)
                return -EINVAL;

        return (int)stride; /* stride or negative errno code */
}
EXPORT_SYMBOL(drm_sysfb_get_stride_si);

s64 drm_sysfb_get_visible_size_si(struct drm_device *dev, const struct screen_info *si,
                                  unsigned int height, unsigned int stride, u64 size)
{
        u64 vsize = mul_u32_u32(height, stride);

        return drm_sysfb_get_validated_size0(dev, "visible size", vsize, size);
}
EXPORT_SYMBOL(drm_sysfb_get_visible_size_si);