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video: Add helpers for decoding screen_info 

The plain values as stored in struct screen_info need to be decoded
before being used. Add helpers that decode the type of video output
and the framebuffer I/O aperture.

Old or non-x86 systems may not set the type of video directly, but
only indicate the presence by storing 0x01 in orig_video_isVGA. The
decoding logic in screen_info_video_type() takes this into account.
It then follows similar code in vgacon's vgacon_startup() to detect
the video type from the given values.

A call to screen_info_resources() returns all known resources of the
given screen_info. The resources' values have been taken from existing
code in vgacon and vga16fb. These drivers can later be converted to
use the new interfaces.

v2:
	* return ssize_t from screen_info_resources()
	* don't call __screen_info_has_lfb() unnecessarily

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240212090736.11464-2-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2024-02-12 10:06:09 +01:00
parent 6b1f93ea34
commit 75fa9b7e37
5 changed files with 254 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/firmware/Kconfig
View File

@ -182,6 +182,7 @@ config MTK_ADSP_IPC
config SYSFB
bool
select BOOT_VESA_SUPPORT
select SCREEN_INFO
config SYSFB_SIMPLEFB
bool "Mark VGA/VBE/EFI FB as generic system framebuffer"

4
drivers/video/Kconfig
View File

@ -11,6 +11,10 @@ config APERTURE_HELPERS
Support tracking and hand-over of aperture ownership. Required
by graphics drivers for firmware-provided framebuffers.
config SCREEN_INFO
bool
default n
config STI_CORE
bool
depends on PARISC

3
drivers/video/Makefile
View File

@ -1,11 +1,14 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_APERTURE_HELPERS) += aperture.o
obj-$(CONFIG_SCREEN_INFO) += screen_info.o
obj-$(CONFIG_STI_CORE) += sticore.o
obj-$(CONFIG_VGASTATE) += vgastate.o
obj-$(CONFIG_VIDEO) += cmdline.o nomodeset.o
obj-$(CONFIG_HDMI) += hdmi.o
screen_info-y := screen_info_generic.o
obj-$(CONFIG_VT) += console/
obj-$(CONFIG_FB_STI) += console/
obj-$(CONFIG_LOGO) += logo/

146
drivers/video/screen_info_generic.c Normal file
View File

@ -0,0 +1,146 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/export.h>
#include <linux/ioport.h>
#include <linux/screen_info.h>
#include <linux/string.h>
static void resource_init_named(struct resource *r,
resource_size_t start, resource_size_t size,
const char *name, unsigned int flags)
{
memset(r, 0, sizeof(*r));
r->start = start;
r->end = start + size - 1;
r->name = name;
r->flags = flags;
}
static void resource_init_io_named(struct resource *r,
resource_size_t start, resource_size_t size,
const char *name)
{
resource_init_named(r, start, size, name, IORESOURCE_IO);
}
static void resource_init_mem_named(struct resource *r,
resource_size_t start, resource_size_t size,
const char *name)
{
resource_init_named(r, start, size, name, IORESOURCE_MEM);
}
static inline bool __screen_info_has_ega_gfx(unsigned int mode)
{
switch (mode) {
case 0x0d: /* 320x200-4 */
case 0x0e: /* 640x200-4 */
case 0x0f: /* 640x350-1 */
case 0x10: /* 640x350-4 */
return true;
default:
return false;
}
}
static inline bool __screen_info_has_vga_gfx(unsigned int mode)
{
switch (mode) {
case 0x10: /* 640x480-1 */
case 0x12: /* 640x480-4 */
case 0x13: /* 320-200-8 */
case 0x6a: /* 800x600-4 (VESA) */
return true;
default:
return __screen_info_has_ega_gfx(mode);
}
}
/**
* screen_info_resources() - Get resources from screen_info structure
* @si: the screen_info
* @r: pointer to an array of resource structures
* @num: number of elements in @r:
*
* Returns:
* The number of resources stored in @r on success, or a negative errno code otherwise.
*
* A call to screen_info_resources() returns the resources consumed by the
* screen_info's device or framebuffer. The result is stored in the caller-supplied
* array @r with up to @num elements. The function returns the number of
* initialized elements.
*/
ssize_t screen_info_resources(const struct screen_info *si, struct resource *r, size_t num)
{
struct resource *pos = r;
unsigned int type = screen_info_video_type(si);
u64 base, size;
switch (type) {
case VIDEO_TYPE_MDA:
if (num > 0)
resource_init_io_named(pos++, 0x3b0, 12, "mda");
if (num > 1)
resource_init_io_named(pos++, 0x3bf, 0x01, "mda");
if (num > 2)
resource_init_mem_named(pos++, 0xb0000, 0x2000, "mda");
break;
case VIDEO_TYPE_CGA:
if (num > 0)
resource_init_io_named(pos++, 0x3d4, 0x02, "cga");
if (num > 1)
resource_init_mem_named(pos++, 0xb8000, 0x2000, "cga");
break;
case VIDEO_TYPE_EGAM:
if (num > 0)
resource_init_io_named(pos++, 0x3bf, 0x10, "ega");
if (num > 1)
resource_init_mem_named(pos++, 0xb0000, 0x8000, "ega");
break;
case VIDEO_TYPE_EGAC:
if (num > 0)
resource_init_io_named(pos++, 0x3c0, 0x20, "ega");
if (num > 1) {
if (__screen_info_has_ega_gfx(si->orig_video_mode))
resource_init_mem_named(pos++, 0xa0000, 0x10000, "ega");
else
resource_init_mem_named(pos++, 0xb8000, 0x8000, "ega");
}
break;
case VIDEO_TYPE_VGAC:
if (num > 0)
resource_init_io_named(pos++, 0x3c0, 0x20, "vga+");
if (num > 1) {
if (__screen_info_has_vga_gfx(si->orig_video_mode))
resource_init_mem_named(pos++, 0xa0000, 0x10000, "vga+");
else
resource_init_mem_named(pos++, 0xb8000, 0x8000, "vga+");
}
break;
case VIDEO_TYPE_VLFB:
case VIDEO_TYPE_EFI:
base = __screen_info_lfb_base(si);
if (!base)
break;
size = __screen_info_lfb_size(si, type);
if (!size)
break;
if (num > 0)
resource_init_mem_named(pos++, base, size, "lfb");
break;
case VIDEO_TYPE_PICA_S3:
case VIDEO_TYPE_MIPS_G364:
case VIDEO_TYPE_SGI:
case VIDEO_TYPE_TGAC:
case VIDEO_TYPE_SUN:
case VIDEO_TYPE_SUNPCI:
case VIDEO_TYPE_PMAC:
default:
/* not supported */
return -EINVAL;
}
return pos - r;
}
EXPORT_SYMBOL(screen_info_resources);

100
include/linux/screen_info.h
View File

@ -4,6 +4,106 @@
#include <uapi/linux/screen_info.h>
/**
* SCREEN_INFO_MAX_RESOURCES - maximum number of resources per screen_info
*/
#define SCREEN_INFO_MAX_RESOURCES 3
struct resource;
static inline bool __screen_info_has_lfb(unsigned int type)
{
return (type == VIDEO_TYPE_VLFB) || (type == VIDEO_TYPE_EFI);
}
static inline u64 __screen_info_lfb_base(const struct screen_info *si)
{
u64 lfb_base = si->lfb_base;
if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
lfb_base |= (u64)si->ext_lfb_base << 32;
return lfb_base;
}
static inline u64 __screen_info_lfb_size(const struct screen_info *si, unsigned int type)
{
u64 lfb_size = si->lfb_size;
if (type == VIDEO_TYPE_VLFB)
lfb_size <<= 16;
return lfb_size;
}
static inline unsigned int __screen_info_video_type(unsigned int type)
{
switch (type) {
case VIDEO_TYPE_MDA:
case VIDEO_TYPE_CGA:
case VIDEO_TYPE_EGAM:
case VIDEO_TYPE_EGAC:
case VIDEO_TYPE_VGAC:
case VIDEO_TYPE_VLFB:
case VIDEO_TYPE_PICA_S3:
case VIDEO_TYPE_MIPS_G364:
case VIDEO_TYPE_SGI:
case VIDEO_TYPE_TGAC:
case VIDEO_TYPE_SUN:
case VIDEO_TYPE_SUNPCI:
case VIDEO_TYPE_PMAC:
case VIDEO_TYPE_EFI:
return type;
default:
return 0;
}
}
/**
* screen_info_video_type() - Decodes the video type from struct screen_info
* @si: an instance of struct screen_info
*
* Returns:
* A VIDEO_TYPE_ constant representing si's type of video display, or 0 otherwise.
*/
static inline unsigned int screen_info_video_type(const struct screen_info *si)
{
unsigned int type;
// check if display output is on
if (!si->orig_video_isVGA)
return 0;
// check for a known VIDEO_TYPE_ constant
type = __screen_info_video_type(si->orig_video_isVGA);
if (type)
return si->orig_video_isVGA;
// check if text mode has been initialized
if (!si->orig_video_lines || !si->orig_video_cols)
return 0;
// 80x25 text, mono
if (si->orig_video_mode == 0x07) {
if ((si->orig_video_ega_bx & 0xff) != 0x10)
return VIDEO_TYPE_EGAM;
else
return VIDEO_TYPE_MDA;
}
// EGA/VGA, 16 colors
if ((si->orig_video_ega_bx & 0xff) != 0x10) {
if (si->orig_video_isVGA)
return VIDEO_TYPE_VGAC;
else
return VIDEO_TYPE_EGAC;
}
// the rest...
return VIDEO_TYPE_CGA;
}
ssize_t screen_info_resources(const struct screen_info *si, struct resource *r, size_t num);
extern struct screen_info screen_info;
#endif /* _SCREEN_INFO_H */