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/* SPDX-License-Identifier: GPL-2.0-only
*
* I/O memory framebuffer access for drawing routines
*
* Copyright (C) 2025 Zsolt Kajtar (soci@c64.rulez.org)
*/
/* keeps track of a bit address in framebuffer memory */
struct fb_address {
void __iomem *address;
int bits;
};
/* initialize the bit address pointer to the beginning of the frame buffer */
static inline struct fb_address fb_address_init(struct fb_info *p)
{
void __iomem *base = p->screen_base;
struct fb_address ptr;
ptr.address = PTR_ALIGN_DOWN(base, BITS_PER_LONG / BITS_PER_BYTE);
ptr.bits = (base - ptr.address) * BITS_PER_BYTE;
return ptr;
}
/* framebuffer write access */
static inline void fb_write_offset(unsigned long val, int offset, const struct fb_address *dst)
{
#if BITS_PER_LONG == 32
fb_writel(val, dst->address + offset * (BITS_PER_LONG / BITS_PER_BYTE));
#else
fb_writeq(val, dst->address + offset * (BITS_PER_LONG / BITS_PER_BYTE));
#endif
}
/* framebuffer read access */
static inline unsigned long fb_read_offset(int offset, const struct fb_address *src)
{
#if BITS_PER_LONG == 32
return fb_readl(src->address + offset * (BITS_PER_LONG / BITS_PER_BYTE));
#else
return fb_readq(src->address + offset * (BITS_PER_LONG / BITS_PER_BYTE));
#endif
}
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