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