vesafb.c

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/*
 * Copyright (C) 2013 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

/** @file
 *
 * VESA frame buffer console
 *
 */

#include <stdlib.h>
#include <errno.h>
#include <limits.h>
#include <realmode.h>
#include <ipxe/console.h>
#include <ipxe/io.h>
#include <ipxe/ansicol.h>
#include <ipxe/fbcon.h>
#include <ipxe/vesafb.h>
#include <config/console.h>

/* Avoid dragging in BIOS console if not otherwise used */
extern struct console_driver bios_console;
struct console_driver bios_console __attribute__ (( weak ));

/* Disambiguate the various error causes */
#define EIO_FAILED __einfo_error ( EINFO_EIO_FAILED )
#define EINFO_EIO_FAILED                                                \
        __einfo_uniqify ( EINFO_EIO, 0x01,                              \
                          "Function call failed" )
#define EIO_HARDWARE __einfo_error ( EINFO_EIO_HARDWARE )
#define EINFO_EIO_HARDWARE                                              \
        __einfo_uniqify ( EINFO_EIO, 0x02,                              \
                          "Not supported in current configuration" )
#define EIO_MODE __einfo_error ( EINFO_EIO_MODE )
#define EINFO_EIO_MODE                                                  \
        __einfo_uniqify ( EINFO_EIO, 0x03,                              \
                          "Invalid in current video mode" )
#define EIO_VBE( code )                                                 \
        EUNIQ ( EINFO_EIO, (code), EIO_FAILED, EIO_HARDWARE, EIO_MODE )

/* Set default console usage if applicable
 *
 * We accept either CONSOLE_FRAMEBUFFER or CONSOLE_VESAFB.
 */
#if ( defined ( CONSOLE_FRAMEBUFFER ) && ! defined ( CONSOLE_VESAFB ) )
#define CONSOLE_VESAFB CONSOLE_FRAMEBUFFER
#endif
#if ! ( defined ( CONSOLE_VESAFB ) && CONSOLE_EXPLICIT ( CONSOLE_VESAFB ) )
#undef CONSOLE_VESAFB
#define CONSOLE_VESAFB ( CONSOLE_USAGE_ALL & ~CONSOLE_USAGE_LOG )
#endif

/** Character height */
#define VESAFB_CHAR_HEIGHT 16

/** Font corresponding to selected character width and height */
#define VESAFB_FONT VBE_FONT_8x16

/** Number of ASCII glyphs within the font */
#define VESAFB_ASCII 128

/** Glyph to render for non-ASCII characters
 *
 * We choose to use one of the box-drawing glyphs.
 */
#define VESAFB_UNKNOWN 0xfe

/* Forward declaration */
struct console_driver vesafb_console __console_driver;

/** A VESA frame buffer */
struct vesafb {
        /** Frame buffer console */
        struct fbcon fbcon;
        /** Physical start address */
        physaddr_t start;
        /** Pixel geometry */
        struct fbcon_geometry pixel;
        /** Colour mapping */
        struct fbcon_colour_map map;
        /** Font definition */
        struct fbcon_font font;
        /** Character glyphs */
        const uint8_t *glyphs;
        /** Saved VGA mode */
        uint8_t saved_mode;
};

/** The VESA frame buffer */
static struct vesafb vesafb;

/** Base memory buffer used for VBE calls */
union vbe_buffer {
        /** VBE controller information block */
        struct vbe_controller_info controller;
        /** VBE mode information block */
        struct vbe_mode_info mode;
};
static union vbe_buffer __bss16 ( vbe_buf );
#define vbe_buf __use_data16 ( vbe_buf )

/**
 * Convert VBE status code to iPXE status code
 *
 * @v status            VBE status code
 * @ret rc              Return status code
 */
static int vesafb_rc ( unsigned int status ) {
        unsigned int code;

        if ( ( status & 0xff ) != 0x4f )
                return -ENOTSUP;
        code = ( ( status >> 8 ) & 0xff );
        return ( code ? -EIO_VBE ( code ) : 0 );
}

/**
 * Get character glyph
 *
 * @v character         Unicode character
 * @ret glyph           Character glyph
 */
static const uint8_t * vesafb_glyph ( unsigned int character ) {
        unsigned int index;

        /* Identify glyph */
        if ( character < VESAFB_ASCII ) {
                /* ASCII character: use corresponding glyph */
                index = character;
        } else {
                /* Non-ASCII character: use "unknown" glyph */
                index = VESAFB_UNKNOWN;
        }

        /* Return glyph in BIOS font table */
        return &vesafb.glyphs[ index * VESAFB_CHAR_HEIGHT ];
}

/**
 * Get font definition
 *
 */
static void vesafb_font ( void ) {
        struct segoff glyphs;

        /* Get font information
         *
         * Working around gcc bugs is icky here.  The value we want is
         * returned in %ebp, but there's no way to specify %ebp in an
         * output constraint.  We can't put %ebp in the clobber list,
         * because this tends to cause random build failures on some
         * gcc versions.  We can't manually push/pop %ebp and return
         * the value via a generic register output constraint, because
         * gcc might choose to use %ebp to satisfy that constraint
         * (and we have no way to prevent it from so doing).
         *
         * Work around this hideous mess by using %ecx and %edx as the
         * output registers, since they get clobbered anyway.
         */
        __asm__ __volatile__ ( REAL_CODE ( "pushw %%bp\n\t" /* gcc bug */
                                           "int $0x10\n\t"
                                           "movw %%es, %%cx\n\t"
                                           "movw %%bp, %%dx\n\t"
                                           "popw %%bp\n\t" /* gcc bug */ )
                               : "=c" ( glyphs.segment ),
                                 "=d" ( glyphs.offset )
                               : "a" ( VBE_GET_FONT ),
                                 "b" ( VESAFB_FONT ) );
        DBGC ( &vbe_buf, "VESAFB has font %04x at %04x:%04x\n",
               VESAFB_FONT, glyphs.segment, glyphs.offset );
        vesafb.glyphs = real_to_virt ( glyphs.segment, glyphs.offset );
        vesafb.font.height = VESAFB_CHAR_HEIGHT;
        vesafb.font.glyph = vesafb_glyph;
}

/**
 * Get VBE mode list
 *
 * @ret mode_numbers    Mode number list (terminated with VBE_MODE_END)
 * @ret rc              Return status code
 *
 * The caller is responsible for eventually freeing the mode list.
 */
static int vesafb_mode_list ( uint16_t **mode_numbers ) {
        struct vbe_controller_info *controller = &vbe_buf.controller;
        const uint16_t *video_mode_ptr;
        const uint16_t *mode_number;
        uint16_t status;
        size_t len;
        int rc;

        /* Avoid returning uninitialised data on error */
        *mode_numbers = NULL;

        /* Get controller information block */
        controller->vbe_signature = 0;
        __asm__ __volatile__ ( REAL_CODE ( "int $0x10" )
                               : "=a" ( status )
                               : "a" ( VBE_CONTROLLER_INFO ),
                                 "D" ( __from_data16 ( controller ) )
                               : "memory", "ebx", "edx" );
        if ( ( rc = vesafb_rc ( status ) ) != 0 ) {
                DBGC ( &vbe_buf, "VESAFB could not get controller information: "
                       "[%04x] %s\n", status, strerror ( rc ) );
                return rc;
        }
        if ( controller->vbe_signature != VBE_CONTROLLER_SIGNATURE ) {
                DBGC ( &vbe_buf, "VESAFB invalid controller signature "
                       "\"%c%c%c%c\"\n", ( controller->vbe_signature >> 0 ),
                       ( controller->vbe_signature >> 8 ),
                       ( controller->vbe_signature >> 16 ),
                       ( controller->vbe_signature >> 24 ) );
                DBGC_HDA ( &vbe_buf, 0, controller, sizeof ( *controller ) );
                return -EINVAL;
        }
        DBGC ( &vbe_buf, "VESAFB found VBE version %d.%d with mode list at "
               "%04x:%04x\n", controller->vbe_major_version,
               controller->vbe_minor_version,
               controller->video_mode_ptr.segment,
               controller->video_mode_ptr.offset );

        /* Calculate length of mode list */
        video_mode_ptr = real_to_virt ( controller->video_mode_ptr.segment,
                                        controller->video_mode_ptr.offset );
        mode_number = video_mode_ptr;
        while ( *(mode_number++) != VBE_MODE_END ) {}
        len = ( ( ( const void * ) mode_number ) -
                ( ( const void * ) video_mode_ptr ) );

        /* Allocate and fill mode list */
        *mode_numbers = malloc ( len );
        if ( ! *mode_numbers )
                return -ENOMEM;
        memcpy ( *mode_numbers, video_mode_ptr, len );

        return 0;
}

/**
 * Get video mode information
 *
 * @v mode_number       Mode number
 * @ret rc              Return status code
 */
static int vesafb_mode_info ( unsigned int mode_number ) {
        struct vbe_mode_info *mode = &vbe_buf.mode;
        uint16_t status;
        int rc;

        /* Get mode information */
        __asm__ __volatile__ ( REAL_CODE ( "int $0x10" )
                               : "=a" ( status )
                               : "a" ( VBE_MODE_INFO ),
                                 "c" ( mode_number ),
                                 "D" ( __from_data16 ( mode ) )
                               : "memory" );
        if ( ( rc = vesafb_rc ( status ) ) != 0 ) {
                DBGC ( &vbe_buf, "VESAFB could not get mode %04x information: "
                       "[%04x] %s\n", mode_number, status, strerror ( rc ) );
                return rc;
        }
        DBGC ( &vbe_buf, "VESAFB mode %04x %dx%d %dbpp(%d:%d:%d:%d) model "
               "%02x [x%d]%s%s%s%s%s\n", mode_number, mode->x_resolution,
               mode->y_resolution, mode->bits_per_pixel, mode->rsvd_mask_size,
               mode->red_mask_size, mode->green_mask_size, mode->blue_mask_size,
               mode->memory_model, ( mode->number_of_image_pages + 1 ),
               ( ( mode->mode_attributes & VBE_MODE_ATTR_SUPPORTED ) ?
                 "" : " [unsupported]" ),
               ( ( mode->mode_attributes & VBE_MODE_ATTR_TTY ) ?
                 " [tty]" : "" ),
               ( ( mode->mode_attributes & VBE_MODE_ATTR_GRAPHICS ) ?
                 "" : " [text]" ),
               ( ( mode->mode_attributes & VBE_MODE_ATTR_LINEAR ) ?
                 "" : " [nonlinear]" ),
               ( ( mode->mode_attributes & VBE_MODE_ATTR_TRIPLE_BUF ) ?
                 " [buf]" : "" ) );

        return 0;
}

/**
 * Set video mode
 *
 * @v mode_number       Mode number
 * @ret rc              Return status code
 */
static int vesafb_set_mode ( unsigned int mode_number ) {
        struct vbe_mode_info *mode = &vbe_buf.mode;
        uint16_t status;
        int rc;

        /* Get mode information */
        if ( ( rc = vesafb_mode_info ( mode_number ) ) != 0 )
                return rc;

        /* Record mode parameters */
        vesafb.start = mode->phys_base_ptr;
        vesafb.pixel.width = mode->x_resolution;
        vesafb.pixel.height = mode->y_resolution;
        vesafb.pixel.len = ( ( mode->bits_per_pixel + 7 ) / 8 );
        vesafb.pixel.stride = mode->bytes_per_scan_line;
        DBGC ( &vbe_buf, "VESAFB mode %04x has frame buffer at %08x\n",
               mode_number, mode->phys_base_ptr );

        /* Initialise font colours */
        vesafb.map.red_scale = ( 8 - mode->red_mask_size );
        vesafb.map.green_scale = ( 8 - mode->green_mask_size );
        vesafb.map.blue_scale = ( 8 - mode->blue_mask_size );
        vesafb.map.red_lsb = mode->red_field_position;
        vesafb.map.green_lsb = mode->green_field_position;
        vesafb.map.blue_lsb = mode->blue_field_position;

        /* Select this mode */
        __asm__ __volatile__ ( REAL_CODE ( "int $0x10" )
                               : "=a" ( status )
                               : "a" ( VBE_SET_MODE ),
                                 "b" ( mode_number ) );
        if ( ( rc = vesafb_rc ( status ) ) != 0 ) {
                DBGC ( &vbe_buf, "VESAFB could not set mode %04x: [%04x] %s\n",
                       mode_number, status, strerror ( rc ) );
                return rc;
        }

        return 0;
}

/**
 * Select video mode
 *
 * @v mode_numbers      Mode number list (terminated with VBE_MODE_END)
 * @v min_width         Minimum required width (in pixels)
 * @v min_height        Minimum required height (in pixels)
 * @v min_bpp           Minimum required colour depth (in bits per pixel)
 * @ret mode_number     Mode number, or negative error
 */
static int vesafb_select_mode ( const uint16_t *mode_numbers,
                                unsigned int min_width, unsigned int min_height,
                                unsigned int min_bpp ) {
        struct vbe_mode_info *mode = &vbe_buf.mode;
        int best_mode_number = -ENOENT;
        unsigned int best_score = INT_MAX;
        unsigned int score;
        uint16_t mode_number;
        int rc;

        /* Find the first suitable mode */
        while ( ( mode_number = *(mode_numbers++) ) != VBE_MODE_END ) {

                /* Force linear mode variant */
                mode_number |= VBE_MODE_LINEAR;

                /* Get mode information */
                if ( ( rc = vesafb_mode_info ( mode_number ) ) != 0 )
                        continue;

                /* Skip unusable modes */
                if ( ( mode->mode_attributes & ( VBE_MODE_ATTR_SUPPORTED |
                                                 VBE_MODE_ATTR_GRAPHICS |
                                                 VBE_MODE_ATTR_LINEAR ) ) !=
                     ( VBE_MODE_ATTR_SUPPORTED | VBE_MODE_ATTR_GRAPHICS |
                       VBE_MODE_ATTR_LINEAR ) ) {
                        continue;
                }
                if ( mode->memory_model != VBE_MODE_MODEL_DIRECT_COLOUR )
                        continue;

                /* Skip modes not meeting the requirements */
                if ( ( mode->x_resolution < min_width ) ||
                     ( mode->y_resolution < min_height ) ||
                     ( mode->bits_per_pixel < min_bpp ) ) {
                        continue;
                }

                /* Select this mode if it has the best (i.e. lowest)
                 * score.  We choose the scoring system to favour
                 * modes close to the specified width and height;
                 * within modes of the same width and height we prefer
                 * a higher colour depth.
                 */
                score = ( ( mode->x_resolution * mode->y_resolution ) -
                          mode->bits_per_pixel );
                if ( score < best_score ) {
                        best_mode_number = mode_number;
                        best_score = score;
                }
        }

        if ( best_mode_number >= 0 ) {
                DBGC ( &vbe_buf, "VESAFB selected mode %04x\n",
                       best_mode_number );
        } else {
                DBGC ( &vbe_buf, "VESAFB found no suitable mode\n" );
        }

        return best_mode_number;
}

/**
 * Restore video mode
 *
 */
static void vesafb_restore ( void ) {
        uint32_t discard_a;

        /* Restore saved VGA mode */
        __asm__ __volatile__ ( REAL_CODE ( "int $0x10" )
                               : "=a" ( discard_a )
                               : "a" ( VBE_SET_VGA_MODE | vesafb.saved_mode ) );
        DBGC ( &vbe_buf, "VESAFB restored VGA mode %#02x\n",
               vesafb.saved_mode );
}

/**
 * Initialise VESA frame buffer
 *
 * @v config            Console configuration, or NULL to reset
 * @ret rc              Return status code
 */
static int vesafb_init ( struct console_configuration *config ) {
        uint32_t discard_b;
        uint16_t *mode_numbers;
        int mode_number;
        int rc;

        /* Record current VGA mode */
        __asm__ __volatile__ ( REAL_CODE ( "int $0x10" )
                               : "=a" ( vesafb.saved_mode ), "=b" ( discard_b )
                               : "a" ( VBE_GET_VGA_MODE ) );
        DBGC ( &vbe_buf, "VESAFB saved VGA mode %#02x\n", vesafb.saved_mode );

        /* Get VESA mode list */
        if ( ( rc = vesafb_mode_list ( &mode_numbers ) ) != 0 )
                goto err_mode_list;

        /* Select mode */
        if ( ( mode_number = vesafb_select_mode ( mode_numbers, config->width,
                                                  config->height,
                                                  config->depth ) ) < 0 ) {
                rc = mode_number;
                goto err_select_mode;
        }

        /* Set mode */
        if ( ( rc = vesafb_set_mode ( mode_number ) ) != 0 )
                goto err_set_mode;

        /* Get font data */
        vesafb_font();

        /* Initialise frame buffer console */
        if ( ( rc = fbcon_init ( &vesafb.fbcon, phys_to_virt ( vesafb.start ),
                                 &vesafb.pixel, &vesafb.map, &vesafb.font,
                                 config ) ) != 0 )
                goto err_fbcon_init;

        free ( mode_numbers );
        return 0;

        fbcon_fini ( &vesafb.fbcon );
 err_fbcon_init:
 err_set_mode:
        vesafb_restore();
 err_select_mode:
        free ( mode_numbers );
 err_mode_list:
        return rc;
}

/**
 * Finalise VESA frame buffer
 *
 */
static void vesafb_fini ( void ) {

        /* Finalise frame buffer console */
        fbcon_fini ( &vesafb.fbcon );

        /* Restore saved VGA mode */
        vesafb_restore();
}

/**
 * Print a character to current cursor position
 *
 * @v character         Character
 */
static void vesafb_putchar ( int character ) {

        fbcon_putchar ( &vesafb.fbcon, character );
}

/**
 * Configure console
 *
 * @v config            Console configuration, or NULL to reset
 * @ret rc              Return status code
 */
static int vesafb_configure ( struct console_configuration *config ) {
        int rc;

        /* Reset console, if applicable */
        if ( ! vesafb_console.disabled ) {
                vesafb_fini();
                bios_console.disabled &= ~CONSOLE_DISABLED_OUTPUT;
                ansicol_reset_magic();
        }
        vesafb_console.disabled = CONSOLE_DISABLED;

        /* Do nothing more unless we have a usable configuration */
        if ( ( config == NULL ) ||
             ( config->width == 0 ) || ( config->height == 0 ) ) {
                return 0;
        }

        /* Initialise VESA frame buffer */
        if ( ( rc = vesafb_init ( config ) ) != 0 )
                return rc;

        /* Mark console as enabled */
        vesafb_console.disabled = 0;
        bios_console.disabled |= CONSOLE_DISABLED_OUTPUT;

        /* Set magic colour to transparent if we have a background picture */
        if ( config->pixbuf )
                ansicol_set_magic_transparent();

        return 0;
}

/** VESA frame buffer console driver */
struct console_driver vesafb_console __console_driver = {
        .usage = CONSOLE_VESAFB,
        .putchar = vesafb_putchar,
        .configure = vesafb_configure,
        .disabled = CONSOLE_DISABLED,
};