fbdev: add drawing functions for framebuffers in system RAM

The generic drawing functions (cfbimgblt, cfbcopyarea, cfbfillrect) assume
that the framebuffer is in IO memory.  However, we have 3 drivers (hecubafb,
arcfb, and vfb) where the framebuffer is allocated from system RAM (via
vmalloc). Using _raw_read/write and family for these drivers (as used in
the cfb* functions) is illegal, especially in other platforms.

Create 3 new drawing functions, based almost entirely from the original
except that the framebuffer memory is assumed to be in system RAM.
These are named as sysimgblt, syscopyarea, and sysfillrect.

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 388 insertions, 0 deletions

diff --git a/drivers/video/syscopyarea.c b/drivers/video/syscopyarea.c
new file mode 100644
index 0000000..e348893
--- /dev/null
+++ b/drivers/video/syscopyarea.c
@@ -0,0 +1,388 @@
+/*
+ *  Generic Bit Block Transfer for frame buffers located in system RAM with
+ *  packed pixels of any depth.
+ *
+ *  Based almost entirely from cfbcopyarea.c (which is based almost entirely
+ *  on Geert Uytterhoeven's copyarea routine)
+ *
+ *      Copyright (C)  2007 Antonino Daplas <adaplas@pol.net>
+ *
+ *  This file is subject to the terms and conditions of the GNU General Public
+ *  License.  See the file COPYING in the main directory of this archive for
+ *  more details.
+ *
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/fb.h>
+#include <linux/slab.h>
+#include <asm/types.h>
+#include <asm/io.h>
+
+    /*
+     *  Compose two values, using a bitmask as decision value
+     *  This is equivalent to (a & mask) | (b & ~mask)
+     */
+
+static inline unsigned long
+comp(unsigned long a, unsigned long b, unsigned long mask)
+{
+    return ((a ^ b) & mask) ^ b;
+}
+
+    /*
+     *  Generic bitwise copy algorithm
+     */
+
+static void
+bitcpy(unsigned long *dst, int dst_idx, const unsigned long *src,
+	int src_idx, int bits, unsigned n)
+{
+	unsigned long first, last;
+	int const shift = dst_idx-src_idx;
+	int left, right;
+
+	first = FB_SHIFT_HIGH(~0UL, dst_idx);
+	last = ~(FB_SHIFT_HIGH(~0UL, (dst_idx+n) % bits));
+
+	if (!shift) {
+		/* Same alignment for source and dest */
+		if (dst_idx+n <= bits) {
+			/* Single word */
+			if (last)
+				first &= last;
+			*dst = comp(*src, *dst, first);
+		} else {
+			/* Multiple destination words */
+			/* Leading bits */
+ 			if (first != ~0UL) {
+				*dst = comp(*src, *dst, first);
+				dst++;
+				src++;
+				n -= bits - dst_idx;
+			}
+
+			/* Main chunk */
+			n /= bits;
+			while (n >= 8) {
+				*dst++ = *src++;
+				*dst++ = *src++;
+				*dst++ = *src++;
+				*dst++ = *src++;
+				*dst++ = *src++;
+				*dst++ = *src++;
+				*dst++ = *src++;
+				*dst++ = *src++;
+				n -= 8;
+			}
+			while (n--)
+				*dst++ = *src++;
+
+			/* Trailing bits */
+			if (last)
+				*dst = comp(*src, *dst, last);
+		}
+	} else {
+		unsigned long d0, d1;
+		int m;
+
+		/* Different alignment for source and dest */
+		right = shift & (bits - 1);
+		left = -shift & (bits - 1);
+
+		if (dst_idx+n <= bits) {
+			/* Single destination word */
+			if (last)
+				first &= last;
+			if (shift > 0) {
+				/* Single source word */
+				*dst = comp(*src >> right, *dst, first);
+			} else if (src_idx+n <= bits) {
+				/* Single source word */
+				*dst = comp(*src << left, *dst, first);
+			} else {
+				/* 2 source words */
+				d0 = *src++;
+				d1 = *src;
+				*dst = comp(d0 << left | d1 >> right, *dst,
+					    first);
+			}
+		} else {
+			/* Multiple destination words */
+			/** We must always remember the last value read,
+			    because in case SRC and DST overlap bitwise (e.g.
+			    when moving just one pixel in 1bpp), we always
+			    collect one full long for DST and that might
+			    overlap with the current long from SRC. We store
+			    this value in 'd0'. */
+			d0 = *src++;
+			/* Leading bits */
+			if (shift > 0) {
+				/* Single source word */
+				*dst = comp(d0 >> right, *dst, first);
+				dst++;
+				n -= bits - dst_idx;
+			} else {
+				/* 2 source words */
+				d1 = *src++;
+				*dst = comp(d0 << left | *dst >> right, *dst, first);
+				d0 = d1;
+				dst++;
+				n -= bits - dst_idx;
+			}
+
+			/* Main chunk */
+			m = n % bits;
+			n /= bits;
+			while (n >= 4) {
+				d1 = *src++;
+				*dst++ = d0 << left | d1 >> right;
+				d0 = d1;
+				d1 = *src++;
+				*dst++ = d0 << left | d1 >> right;
+				d0 = d1;
+				d1 = *src++;
+				*dst++ = d0 << left | d1 >> right;
+				d0 = d1;
+				d1 = *src++;
+				*dst++ = d0 << left | d1 >> right;
+				d0 = d1;
+				n -= 4;
+			}
+			while (n--) {
+				d1 = *src++;
+				*dst++ = d0 << left | d1 >> right;
+				d0 = d1;
+			}
+
+			/* Trailing bits */
+			if (last) {
+				if (m <= right) {
+					/* Single source word */
+					*dst = comp(d0 << left, *dst, last);
+				} else {
+					/* 2 source words */
+ 					d1 = *src;
+					*dst = comp(d0 << left | d1 >> right,
+						    *dst, last);
+				}
+			}
+		}
+	}
+}
+
+    /*
+     *  Generic bitwise copy algorithm, operating backward
+     */
+
+static void
+bitcpy_rev(unsigned long *dst, int dst_idx, const unsigned long *src,
+	   int src_idx, int bits, unsigned n)
+{
+	unsigned long first, last;
+	int shift;
+
+	dst += (n-1)/bits;
+	src += (n-1)/bits;
+	if ((n-1) % bits) {
+		dst_idx += (n-1) % bits;
+		dst += dst_idx >> (ffs(bits) - 1);
+		dst_idx &= bits - 1;
+		src_idx += (n-1) % bits;
+		src += src_idx >> (ffs(bits) - 1);
+		src_idx &= bits - 1;
+	}
+
+	shift = dst_idx-src_idx;
+
+	first = FB_SHIFT_LOW(~0UL, bits - 1 - dst_idx);
+	last = ~(FB_SHIFT_LOW(~0UL, bits - 1 - ((dst_idx-n) % bits)));
+
+	if (!shift) {
+		/* Same alignment for source and dest */
+		if ((unsigned long)dst_idx+1 >= n) {
+			/* Single word */
+			if (last)
+				first &= last;
+			*dst = comp(*src, *dst, first);
+		} else {
+			/* Multiple destination words */
+
+			/* Leading bits */
+			if (first != ~0UL) {
+				*dst = comp(*src, *dst, first);
+				dst--;
+				src--;
+				n -= dst_idx+1;
+			}
+
+			/* Main chunk */
+			n /= bits;
+			while (n >= 8) {
+				*dst-- = *src--;
+				*dst-- = *src--;
+				*dst-- = *src--;
+				*dst-- = *src--;
+				*dst-- = *src--;
+				*dst-- = *src--;
+				*dst-- = *src--;
+				*dst-- = *src--;
+				n -= 8;
+			}
+			while (n--)
+				*dst-- = *src--;
+			/* Trailing bits */
+			if (last)
+				*dst = comp(*src, *dst, last);
+		}
+	} else {
+		/* Different alignment for source and dest */
+
+		int const left = -shift & (bits-1);
+		int const right = shift & (bits-1);
+
+		if ((unsigned long)dst_idx+1 >= n) {
+			/* Single destination word */
+			if (last)
+				first &= last;
+			if (shift < 0) {
+				/* Single source word */
+				*dst = comp(*src << left, *dst, first);
+			} else if (1+(unsigned long)src_idx >= n) {
+				/* Single source word */
+				*dst = comp(*src >> right, *dst, first);
+			} else {
+				/* 2 source words */
+				*dst = comp(*src >> right | *(src-1) << left,
+					    *dst, first);
+			}
+		} else {
+			/* Multiple destination words */
+			/** We must always remember the last value read,
+			    because in case SRC and DST overlap bitwise (e.g.
+			    when moving just one pixel in 1bpp), we always
+			    collect one full long for DST and that might
+			    overlap with the current long from SRC. We store
+			    this value in 'd0'. */
+			unsigned long d0, d1;
+			int m;
+
+			d0 = *src--;
+			/* Leading bits */
+			if (shift < 0) {
+				/* Single source word */
+				*dst = comp(d0 << left, *dst, first);
+			} else {
+				/* 2 source words */
+				d1 = *src--;
+				*dst = comp(d0 >> right | d1 << left, *dst,
+					    first);
+				d0 = d1;
+			}
+			dst--;
+			n -= dst_idx+1;
+
+			/* Main chunk */
+			m = n % bits;
+			n /= bits;
+			while (n >= 4) {
+				d1 = *src--;
+				*dst-- = d0 >> right | d1 << left;
+				d0 = d1;
+				d1 = *src--;
+				*dst-- = d0 >> right | d1 << left;
+				d0 = d1;
+				d1 = *src--;
+				*dst-- = d0 >> right | d1 << left;
+				d0 = d1;
+				d1 = *src--;
+				*dst-- = d0 >> right | d1 << left;
+				d0 = d1;
+				n -= 4;
+			}
+			while (n--) {
+				d1 = *src--;
+				*dst-- = d0 >> right | d1 << left;
+				d0 = d1;
+			}
+
+			/* Trailing bits */
+			if (last) {
+				if (m <= left) {
+					/* Single source word */
+					*dst = comp(d0 >> right, *dst, last);
+				} else {
+					/* 2 source words */
+					d1 = *src;
+					*dst = comp(d0 >> right | d1 << left,
+						    *dst, last);
+				}
+			}
+		}
+	}
+}
+
+void sys_copyarea(struct fb_info *p, const struct fb_copyarea *area)
+{
+	u32 dx = area->dx, dy = area->dy, sx = area->sx, sy = area->sy;
+	u32 height = area->height, width = area->width;
+	unsigned long const bits_per_line = p->fix.line_length*8u;
+	unsigned long *dst = NULL, *src = NULL;
+	int bits = BITS_PER_LONG, bytes = bits >> 3;
+	int dst_idx = 0, src_idx = 0, rev_copy = 0;
+
+	if (p->state != FBINFO_STATE_RUNNING)
+		return;
+
+	/* if the beginning of the target area might overlap with the end of
+	the source area, be have to copy the area reverse. */
+	if ((dy == sy && dx > sx) || (dy > sy)) {
+		dy += height;
+		sy += height;
+		rev_copy = 1;
+	}
+
+	/* split the base of the framebuffer into a long-aligned address and
+	   the index of the first bit */
+	dst = src = (unsigned long *)((unsigned long)p->screen_base &
+				      ~(bytes-1));
+	dst_idx = src_idx = 8*((unsigned long)p->screen_base & (bytes-1));
+	/* add offset of source and target area */
+	dst_idx += dy*bits_per_line + dx*p->var.bits_per_pixel;
+	src_idx += sy*bits_per_line + sx*p->var.bits_per_pixel;
+
+	if (p->fbops->fb_sync)
+		p->fbops->fb_sync(p);
+
+	if (rev_copy) {
+		while (height--) {
+			dst_idx -= bits_per_line;
+			src_idx -= bits_per_line;
+			dst += dst_idx >> (ffs(bits) - 1);
+			dst_idx &= (bytes - 1);
+			src += src_idx >> (ffs(bits) - 1);
+			src_idx &= (bytes - 1);
+			bitcpy_rev(dst, dst_idx, src, src_idx, bits,
+				width*p->var.bits_per_pixel);
+		}
+	} else {
+		while (height--) {
+			dst += dst_idx >> (ffs(bits) - 1);
+			dst_idx &= (bytes - 1);
+			src += src_idx >> (ffs(bits) - 1);
+			src_idx &= (bytes - 1);
+			bitcpy(dst, dst_idx, src, src_idx, bits,
+				width*p->var.bits_per_pixel);
+			dst_idx += bits_per_line;
+			src_idx += bits_per_line;
+		}
+	}
+}
+
+EXPORT_SYMBOL(sys_copyarea);
+
+MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>");
+MODULE_DESCRIPTION("Generic copyarea (sys-to-sys)");
+MODULE_LICENSE("GPL");
+