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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 3/7] xen: introduce a generic framebuffer driver
On Wed, 9 Jan 2013, Jan Beulich wrote:
> >>> On 08.01.13 at 21:03, Stefano Stabellini
> >>> <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> > --- /dev/null
> > +++ b/xen/drivers/video/lfb.c
> > @@ -0,0 +1,206 @@
> > +/******************************************************************************
> > + * lfb.c
> > + *
> > + * linear frame buffer handling.
> > + */
> > +
> > +#include <xen/config.h>
> > +#include <xen/kernel.h>
> > +#include <xen/lib.h>
> > +#include <xen/errno.h>
> > +#include "lfb.h"
> > +#include "font.h"
> > +
> > +#define MAX_XRES 1900
> > +#define MAX_YRES 1200
> > +#define MAX_BPP 4
> > +#define MAX_FONT_W 8
> > +#define MAX_FONT_H 16
> > +static __initdata unsigned int line_len[MAX_XRES / MAX_FONT_W];
> > +static __initdata unsigned char lbuf[MAX_XRES * MAX_BPP];
> > +static __initdata unsigned char text_buf[(MAX_XRES / MAX_FONT_W) * \
> > + (MAX_YRES / MAX_FONT_H)];
>
> Imo it would be better to move all these __initdata definitions
> do to where the using __init functions actually live, to make
> sure unintended use of them in non-__init ones is noticed.
OK
> > +
> > +struct lfb_status {
> > + struct lfb_prop lfbp;
> > +
> > + unsigned char *lbuf, *text_buf;
> > + unsigned int *line_len;
> > + unsigned int xpos, ypos;
> > +};
> > +static struct lfb_status lfb;
> > +
> > +static void lfb_show_line(
> > + const unsigned char *text_line,
> > + unsigned char *video_line,
> > + unsigned int nr_chars,
> > + unsigned int nr_cells)
> > +{
> > + unsigned int i, j, b, bpp, pixel;
> > +
> > + bpp = (lfb.lfbp.bits_per_pixel + 7) >> 3;
> > +
> > + for ( i = 0; i < lfb.lfbp.font->height; i++ )
> > + {
> > + unsigned char *ptr = lfb.lbuf;
> > +
> > + for ( j = 0; j < nr_chars; j++ )
> > + {
> > + const unsigned char *bits = lfb.lfbp.font->data;
> > + bits += ((text_line[j] * lfb.lfbp.font->height + i) *
> > + ((lfb.lfbp.font->width + 7) >> 3));
> > + for ( b = lfb.lfbp.font->width; b--; )
> > + {
> > + pixel = (*bits & (1u<<b)) ? lfb.lfbp.pixel_on : 0;
> > + memcpy(ptr, &pixel, bpp);
> > + ptr += bpp;
> > + }
> > + }
> > +
> > + memset(ptr, 0, (lfb.lfbp.width - nr_chars * lfb.lfbp.font->width)
> > * bpp);
> > + memcpy(video_line, lfb.lbuf, nr_cells * lfb.lfbp.font->width *
> > bpp);
> > + video_line += lfb.lfbp.bytes_per_line;
> > + }
> > +}
> > +
> > +/* Fast mode which redraws all modified parts of a 2D text buffer. */
> > +void lfb_redraw_puts(const char *s)
> > +{
> > + unsigned int i, min_redraw_y = lfb.ypos;
> > + char c;
> > +
> > + /* Paste characters into text buffer. */
> > + while ( (c = *s++) != '\0' )
> > + {
> > + if ( (c == '\n') || (lfb.xpos >= lfb.lfbp.text_columns) )
> > + {
> > + if ( ++lfb.ypos >= lfb.lfbp.text_rows )
> > + {
> > + min_redraw_y = 0;
> > + lfb.ypos = lfb.lfbp.text_rows - 1;
> > + memmove(lfb.text_buf, lfb.text_buf + lfb.lfbp.text_columns,
> > + lfb.ypos * lfb.lfbp.text_columns);
> > + memset(lfb.text_buf + lfb.ypos * lfb.lfbp.text_columns, 0,
> > lfb.xpos);
> > + }
> > + lfb.xpos = 0;
> > + }
> > +
> > + if ( c != '\n' )
> > + lfb.text_buf[lfb.xpos++ + lfb.ypos * lfb.lfbp.text_columns] =
> > c;
> > + }
> > +
> > + /* Render modified section of text buffer to VESA linear framebuffer.
> > */
> > + for ( i = min_redraw_y; i <= lfb.ypos; i++ )
> > + {
> > + const unsigned char *line = lfb.text_buf + i *
> > lfb.lfbp.text_columns;
> > + unsigned int width;
> > +
> > + for ( width = lfb.lfbp.text_columns; width; --width )
> > + if ( line[width - 1] )
> > + break;
> > + lfb_show_line(line,
> > + lfb.lfbp.lfb + i * lfb.lfbp.font->height *
> > lfb.lfbp.bytes_per_line,
> > + width, max(lfb.line_len[i], width));
> > + lfb.line_len[i] = width;
> > + }
> > +
> > + lfb.lfbp.flush();
> > +}
> > +
> > +/* Slower line-based scroll mode which interacts better with dom0. */
> > +void lfb_scroll_puts(const char *s)
> > +{
> > + unsigned int i;
> > + char c;
> > +
> > + while ( (c = *s++) != '\0' )
> > + {
> > + if ( (c == '\n') || (lfb.xpos >= lfb.lfbp.text_columns) )
> > + {
> > + unsigned int bytes = (lfb.lfbp.width *
> > + ((lfb.lfbp.bits_per_pixel + 7) >> 3));
> > + unsigned char *src = lfb.lfbp.lfb + lfb.lfbp.font->height *
> > lfb.lfbp.bytes_per_line;
> > + unsigned char *dst = lfb.lfbp.lfb;
> > +
> > + /* New line: scroll all previous rows up one line. */
> > + for ( i = lfb.lfbp.font->height; i < lfb.lfbp.height; i++ )
> > + {
> > + memcpy(dst, src, bytes);
> > + src += lfb.lfbp.bytes_per_line;
> > + dst += lfb.lfbp.bytes_per_line;
> > + }
> > +
> > + /* Render new line. */
> > + lfb_show_line(
> > + lfb.text_buf,
> > + lfb.lfbp.lfb + (lfb.lfbp.text_rows-1) *
> > lfb.lfbp.font->height * lfb.lfbp.bytes_per_line,
>
> Long line?
Right
> > + lfb.xpos, lfb.lfbp.text_columns);
> > +
> > + lfb.xpos = 0;
> > + }
> > +
> > + if ( c != '\n' )
> > + lfb.text_buf[lfb.xpos++] = c;
> > + }
> > +
> > + lfb.lfbp.flush();
> > +}
> > +
> > +void lfb_carriage_return(void)
> > +{
> > + lfb.xpos = 0;
> > +}
> > +
> > +int __init lfb_init(struct lfb_prop *lfbp)
> > +{
> > + if ( lfbp->width > MAX_XRES || lfbp->height > MAX_YRES )
> > + {
> > + printk(XENLOG_WARNING "Couldn't initialize a %ux%u framebuffer
> > early.\n",
> > + lfbp->width, lfbp->height);
>
> Indentation?
OK
> > + return -EINVAL;
> > + }
> > +
> > + lfb.lfbp = *lfbp;
> > + lfb.lbuf = lbuf;
> > + lfb.text_buf = text_buf;
> > + lfb.line_len = line_len;
> > + return 0;
> > +}
> > +
> > +int __init lfb_alloc(void)
> > +{
> > + lfb.lbuf = NULL;
> > + lfb.text_buf = NULL;
> > + lfb.line_len = NULL;
> > +
> > + lfb.lbuf = xmalloc_bytes(lfb.lfbp.bytes_per_line);
> > + if ( !lfb.lbuf )
> > + goto fail;
> > +
> > + lfb.text_buf = xzalloc_bytes(lfb.lfbp.text_columns *
> > lfb.lfbp.text_rows);
> > + if ( !lfb.text_buf )
> > + goto fail;
> > +
> > + lfb.line_len = xzalloc_array(unsigned int, lfb.lfbp.text_columns);
> > + if ( !lfb.line_len )
> > + goto fail;
> > +
> > + memcpy(lfb.lbuf, lbuf, lfb.lfbp.bytes_per_line);
> > + memcpy(lfb.text_buf, text_buf, lfb.lfbp.text_columns *
> > lfb.lfbp.text_rows);
> > + memcpy(lfb.line_len, line_len, lfb.lfbp.text_columns);
> > +
> > + return 0;
> > +
> > +fail:
> > + printk(XENLOG_ERR "Couldn't allocate enough memory to drive the
> > framebuffer\n");
> > + lfb_free();
> > +
> > + return -ENOMEM;
> > +}
> > +
> > +void lfb_free(void)
> > +{
> > + xfree(lfb.lbuf);
> > + xfree(lfb.text_buf);
> > + xfree(lfb.line_len);
> > +}
>
>
> This function would then perhaps better go before the __init stuff.
>
> > @@ -139,15 +131,14 @@ void __init vesa_init(void)
> > else
> > {
> > /* White(ish) in default pseudocolor palette. */
> > - pixel_on = 7;
> > + fbp.pixel_on = 7;
> > }
> >
> > - return;
> > -
> > - fail:
> > - xfree(lbuf);
> > - xfree(text_buf);
> > - xfree(line_len);
> > + if ( lfb_init(&lfbp) < 0 )
> > + return;
> > + if ( lfb_alloc() < 0 )
> > + return;
>
> What's the point of calling lfb_alloc() right after lfb_init()? The static
> buffers set up by lfb_init() will get replaced by dynamically allocated
> ones right away. Or in other words - what do you need the static
> buffers for in the first place?
The idea was that you could have output on the screen before xmalloc
works.
Given that vesa_init is always called after xmalloc is available we call
lfb_alloc() right away. Thanks to the fact that I moved setup_mm()
earlier in the ARM version of start_xen, that should be now possible for the
arm_hdlcd driver too. I'll to remove lfb_alloc.
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