cmd: add vbe modesetting command

Adds command `vbe` for setting up graphics mode using VESA VBE 2.0 real
mode interface. The command checks whether a specified mode
(preferred/fallback) is supported by the VGA controller, fetches its
details, sets it and stores necessary info (width, height, bpp,
framebuffer address, etc.) in the syspage. The info can be then queried
using platformctl by userspace apps

JIRA: RTOS-906

cmds/Makefile

@@ -8,7 +8,7 @@
 
 PLO_ALLCOMMANDS = alias app bankswitch bitstream blob bootcm4 bootrom bridge call console \
   copy devices dump echo erase go help jffs2 kernel kernelimg lspci map mem mpu otp phfs \
-  ptable reboot script stop test-dev test-ddr wait
+  ptable reboot script stop test-dev test-ddr wait vbe
 
 PLO_COMMANDS ?= $(PLO_ALLCOMMANDS)
 PLO_APPLETS = $(filter $(PLO_ALLCOMMANDS), $(PLO_COMMANDS))

cmds/vbe.c

@@ -0,0 +1,336 @@
+/*
+ * Phoenix-RTOS
+ *
+ * Operating system loader
+ *
+ * VESA VBE modesetting
+ *
+ * Copyright 2024 Phoenix Systems
+ * Author: Adam Greloch
+ *
+ * This file is part of Phoenix-RTOS.
+ *
+ * %LICENSE%
+ */
+
+#include "cmd.h"
+
+#include <hal/hal.h>
+#include <lib/lib.h>
+#include <syspage.h>
+
+
+#define PTR_TO_SEG(ptr)       ((addr_t)ptr >> 4)
+#define SEGOFS_TO_PTR(segofs) ((addr_t)((segofs & 0xffff0000) >> 12) + (segofs & 0xffff))
+
+#define SUPPORTS_LFB (0x80)
+
+
+typedef struct {
+	u16 width;
+	u16 height;
+	u16 bpp;
+} video_mode_t;
+
+
+/* Structure definitions follow "VESA BIOS EXTENSION (VBE) Core Functions
+ * Standard Version: 3.0", Video Electronics Standards Association, 1998 */
+
+typedef struct {
+	char VbeSignature[4];
+	u16 VbeVersion;
+	u32 OemStringPtr;
+	u32 Capabilities;
+	u32 VideoModePtr;
+	u16 TotalMemory;
+
+	u16 OemSoftwareRev;
+	u32 OemVendorNamePtr;
+	u32 OemProductNamePtr;
+	u32 OemProductRevPtr;
+	char Reserved[222];
+
+	char OemData[256];
+} __attribute__((packed)) vbe_info_block_t;
+
+
+typedef struct {
+	/* Mandatory information for all VBE revisions */
+	u16 ModeAttributes;
+	u8 WinAAttributes;
+	u8 WinBAttributes;
+	u16 WinGranularity;
+	u16 WinSize;
+	u16 WinASegment;
+	u16 WinBSegment;
+	u32 WinFuncPtr;
+	u16 BytesPerScanLine;
+
+	/* Mandatory information for VBE 1.2 and above */
+	u16 XResolution;
+	u16 YResolution;
+	u8 XCharSize;
+	u8 YCharSize;
+	u8 NumberOfPlanes;
+	u8 BitsPerPixel;
+	u8 NumberOfBanks;
+	u8 MemoryModel;
+	u8 BankSize;
+	u8 NumberOfImagePages;
+	u8 Reserved0;
+
+	u8 RedMaskSize;
+	u8 RedFieldPosition;
+	u8 GreenMaskSize;
+	u8 GreenFieldPosition;
+	u8 BlueMaskSize;
+	u8 BlueFieldPosition;
+	u8 RsvdMaskSize;
+	u8 RsvdFieldPosition;
+	u8 DirectColorModeInfo;
+
+	/* Mandatory information for VBE 2.0 and above */
+	u32 PhysBasePtr;
+	u8 Reserved1[212];
+} __attribute__((packed)) vbe_mode_info_block_t;
+
+
+static struct {
+	video_mode_t preferred;
+	video_mode_t fallback;
+	vbe_info_block_t *info;
+	vbe_mode_info_block_t *modeInfo;
+} vbe_common = {
+	.preferred = { 1280, 800, 32 },
+	.fallback = { 1024, 768, 32 },
+
+	/* ADDR_VBE_INFO, ADDR_VBE_MODE_INFO should be aligned to 0x10, so that they can
+	 * be referenced from 8086 emulation mode using segment register only (es=(ADDR >> 4), di=0) */
+	.info = (vbe_info_block_t *)ADDR_VBE_INFO,
+	.modeInfo = (vbe_mode_info_block_t *)ADDR_VBE_MODE_INFO,
+};
+
+
+static int _vbe_infoGet(void)
+{
+	int ax;
+
+	/* indicate support for VBE 2.0+ */
+	hal_memset(vbe_common.info, 0, sizeof(vbe_info_block_t));
+	hal_strcpy(vbe_common.info->VbeSignature, "VBE2");
+
+	ax = 0x4f00;
+
+	/* clang-format off */
+	__asm__ volatile (
+		"pushl $0x10;\n\t"
+		"pushl $0x0;\n\t"
+		"pushl %1;\n\t"
+		"xorw %%di, %%di;\n\t"
+		"call _interrupts_bios;\n\t"
+		"addl $0xc, %%esp;\n\t"
+		: "+a" (ax)
+		: "r" (PTR_TO_SEG(vbe_common.info))
+		: "edi", "memory", "cc");
+	/* clang-format on */
+
+	return ax == 0x4f ? 0 : -1;
+}
+
+
+static int _vbe_modeInfoGet(u16 mode)
+{
+	int ax;
+
+	hal_memset(vbe_common.modeInfo, 0, sizeof(vbe_info_block_t));
+
+	ax = 0x4f01;
+
+	/* clang-format off */
+	__asm__ volatile (
+		"pushl $0x10;\n\t"
+		"pushl $0x0;\n\t"
+		"pushl %1;\n\t"
+		"xorw %%di, %%di;\n\t"
+		"call _interrupts_bios;\n\t"
+		"addl $0xc, %%esp;\n\t"
+		: "+a" (ax)
+		: "r" (PTR_TO_SEG(vbe_common.modeInfo)), "cx" (mode)
+		: "edi", "memory", "cc");
+	/* clang-format on */
+
+	return ax == 0x4f ? 0 : -1;
+}
+
+
+static int _vbe_modeSet(u16 mode)
+{
+	int ax = 0x4f02;
+
+	mode |= (1 << 14);  /* enable linear framebuffer */
+	mode &= ~(1 << 15); /* don't clear the screen */
+
+	/* clang-format off */
+	__asm__ volatile (
+		"pushl $0x10;\n\t"
+		"pushl $0x0;\n\t"
+		"pushl $0x0;\n\t"
+		"xorw %%di, %%di;\n\t"
+		"call _interrupts_bios;\n\t"
+		"addl $0xc, %%esp;\n\t"
+		: "+a" (ax)
+		: "b" (mode)
+		: "edi", "memory", "cc");
+	/* clang-format on */
+
+	return ax == 0x4f ? 0 : -1;
+}
+
+
+static int _vbe_modeFind(graphmode_t *picked)
+{
+	int i, err;
+
+	u16 *modeIds = (u16 *)SEGOFS_TO_PTR(vbe_common.info->VideoModePtr);
+
+	int fallbackModeId = -1;
+	graphmode_t fallback = { 0 };
+
+	for (i = 0; modeIds[i] != 0xffff; i++) {
+		err = _vbe_modeInfoGet(modeIds[i]);
+		if (err < 0) {
+			return -1;
+		}
+
+		if ((vbe_common.modeInfo->ModeAttributes & SUPPORTS_LFB) != 0) {
+			if ((vbe_common.modeInfo->XResolution == vbe_common.preferred.width) && (vbe_common.modeInfo->YResolution == vbe_common.preferred.height) && (vbe_common.modeInfo->BitsPerPixel == vbe_common.preferred.bpp)) {
+				picked->width = vbe_common.modeInfo->XResolution;
+				picked->height = vbe_common.modeInfo->YResolution;
+				picked->bpp = vbe_common.modeInfo->BitsPerPixel;
+				picked->pitch = vbe_common.modeInfo->BytesPerScanLine;
+				picked->framebuffer = vbe_common.modeInfo->PhysBasePtr;
+
+				return modeIds[i];
+			}
+
+			if ((vbe_common.modeInfo->XResolution == vbe_common.fallback.width) && (vbe_common.modeInfo->YResolution == vbe_common.fallback.height) && (vbe_common.modeInfo->BitsPerPixel == vbe_common.fallback.bpp)) {
+				fallbackModeId = modeIds[i];
+				fallback.width = vbe_common.modeInfo->XResolution;
+				fallback.height = vbe_common.modeInfo->YResolution;
+				fallback.bpp = vbe_common.modeInfo->BitsPerPixel;
+				fallback.pitch = vbe_common.modeInfo->BytesPerScanLine;
+				fallback.framebuffer = vbe_common.modeInfo->PhysBasePtr;
+			}
+		}
+	}
+
+	hal_memcpy(picked, &fallback, sizeof(graphmode_t));
+	return fallbackModeId;
+}
+
+
+static int vbe_videoModeParse(char *str, video_mode_t *video_mode)
+{
+	unsigned int val;
+	char *ptr = str;
+
+	if ((ptr == NULL) || (*ptr == '\0')) {
+		return -EINVAL;
+	}
+
+	val = lib_strtoul(ptr, &ptr, 0);
+	if (*ptr != 'x') {
+		return -EINVAL;
+	}
+	video_mode->width = val;
+
+	ptr++;
+	val = lib_strtoul(ptr, &ptr, 0);
+	if (*ptr != 'x') {
+		return -EINVAL;
+	}
+	video_mode->height = val;
+
+	ptr++;
+	val = lib_strtoul(ptr, &ptr, 0);
+	if (*ptr != '\0') {
+		return -EINVAL;
+	}
+	video_mode->bpp = val;
+
+	return 0;
+}
+
+
+static void cmd_usage(const char *name)
+{
+	lib_printf(
+		"Usage: %s <options>\n"
+		"\t-p W:H:BPP   preferred mode (default: %dx%dx%d)\n"
+		"\t-f W:H:BPP   fallback mode (default: %dx%dx%d)\n"
+		"\t-h           prints help\n",
+		name, vbe_common.preferred.width, vbe_common.preferred.height, vbe_common.preferred.bpp,
+		vbe_common.fallback.width, vbe_common.fallback.height, vbe_common.fallback.bpp);
+}
+
+
+static void cmd_vbeInfo(void)
+{
+	lib_printf("sets graphics mode using VESA VBE");
+}
+
+
+static int cmd_vbeMain(int argc, char *argv[])
+{
+	int opt, err;
+	graphmode_t graphmode;
+
+	lib_printf("\n");
+
+	for (;;) {
+		opt = lib_getopt(argc, argv, "p:f:h");
+		if (opt == -1) {
+			break;
+		}
+
+		if (opt == 'p') {
+			vbe_videoModeParse(optarg, &vbe_common.preferred);
+			continue;
+		}
+
+		if (opt == 'f') {
+			vbe_videoModeParse(optarg, &vbe_common.fallback);
+			continue;
+		}
+
+		cmd_usage(argv[0]);
+		return CMD_EXIT_FAILURE;
+	}
+
+	do {
+		err = _vbe_infoGet();
+		if (err < 0) {
+			break;
+		}
+
+		err = _vbe_modeFind(&graphmode);
+		if (err < 0) {
+			break;
+		}
+
+		syspage_graphmodeSet(graphmode);
+
+		_vbe_modeSet(err);
+	} while (0);
+
+	if (err < 0) {
+		lib_printf("\n%s: not supported, skipping", argv[0]);
+	}
+
+	return CMD_EXIT_SUCCESS;
+}
+
+
+static const cmd_t vbe_cmd __attribute__((section("commands"), used)) = {
+	.name = "vbe", .run = cmd_vbeMain, .info = cmd_vbeInfo
+};

hal/ia32/Makefile

@@ -10,7 +10,7 @@ CFLAGS += -DVADDR_KERNEL_BASE=$(VADDR_KERNEL_BASE)
 CFLAGS += -Ihal/ia32
 
 PLO_COMMANDS ?= alias app blob call console copy devices dump echo go help kernel lspci map mem \
-  phfs script reboot stop syspage wait
+  phfs script reboot stop syspage wait vbe
 
 PLO_ALLDEVICES := disk-bios tty-bios uart-16550
 

hal/ia32/config.h

@@ -37,6 +37,9 @@ extern void _interrupts_bios(unsigned char intr, unsigned short ds, unsigned sho
 #define PATH_KERNEL "phoenix-ia32-generic.elf"
 
 
+/* Platform can set graphic modes (i.e. via VBE) */
+#define HAS_GRAPHICS 1
+
 
 /* Import platform specific definitions */
 #include "ld/ia32-generic.ldt"

hal/ia32/memory.c

@@ -137,6 +137,8 @@ int hal_memoryGetNextEntry(addr_t start, addr_t end, mapent_t *entry)
 		{ .start = (addr_t)__stack_limit, .end = (addr_t)__stack_top, .type = hal_entryTemp },
 		{ .start = ADDR_GDT, .end = ADDR_GDT + SIZE_GDT, .type = hal_entryTemp },
 		{ .start = ADDR_IDT, .end = ADDR_IDT + SIZE_IDT, .type = hal_entryTemp },
+		{ .start = ADDR_VBE_INFO, .end = ADDR_VBE_INFO + SIZE_VBE_INFO, .type = hal_entryTemp },
+		{ .start = ADDR_VBE_MODE_INFO, .end = ADDR_VBE_MODE_INFO + SIZE_VBE_MODE_INFO, .type = hal_entryTemp },
 		/* TODO: this entry should be removed after changes in disk-bios */
 		{ .start = ADDR_RCACHE, .end = ADDR_RCACHE + SIZE_RCACHE + SIZE_WCACHE, .type = hal_entryTemp },
 	};

ld/ia32-generic.ldt

@@ -33,6 +33,13 @@
 #define ADDR_PDIR   0x3000
 #define ADDR_PTABLE 0x4000
 
+/* VBE info/mode info structs */
+#define ADDR_VBE_INFO      0x77c00
+#define SIZE_VBE_INFO      0x200
+
+#define ADDR_VBE_MODE_INFO 0x77e00
+#define SIZE_VBE_MODE_INFO 0x100
+
 /* Disk caches (below upper memory starting at 0x80000) */
 #define ADDR_RCACHE 0x78000
 #define SIZE_RCACHE 0x4000