fb: expose framebuffer devices to userspace

kernel-src/arch/x86-64/main.c

@@ -24,6 +24,7 @@
 #include <kernel/console.h>
 #include <kernel/dpc.h>
 #include <kernel/pipefs.h>
+#include <kernel/fb.h>
 
 static cpu_t bsp_cpu;
 
@@ -66,6 +67,7 @@ void kernel_entry() {
 	pseudodevices_init();
 	keyboard_init();
 	arch_ps2_init();
+	fb_init();
 
 	console_init();
 	logging_sethook(console_putc);

kernel-src/include/kernel/devfs.h

@@ -9,6 +9,7 @@
 #define DEV_MAJOR_FULL 2
 #define DEV_MAJOR_ZERO 3
 #define DEV_MAJOR_CONSOLE 4
+#define DEV_MAJOR_FB 5
 
 typedef struct {
 	int (*open)(int minor, int flags);

kernel-src/include/kernel/fb.h

@@ -0,0 +1,6 @@
+#ifndef _FB_H
+#define _FB_h
+
+void fb_init();
+
+#endif

kernel-src/io/fb.c

@@ -1,6 +1,239 @@
 #include <limine.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <logging.h>
+#include <kernel/alloc.h>
+#include <kernel/devfs.h>
+#include <arch/cpu.h>
+#include <kernel/pmm.h>
+
+typedef struct bitfield_t {
+	uint32_t offset;
+	uint32_t length;
+	uint32_t msb_right;
+} bitfield_t;
+
+typedef struct {
+	uint32_t xres;
+	uint32_t yres;
+	uint32_t xres_virtual;
+	uint32_t yres_virtual;
+	uint32_t xoffset;
+	uint32_t yoffset;
+	uint32_t bits_per_pixel;
+	uint32_t grayscale;
+	bitfield_t red;
+	bitfield_t green;
+	bitfield_t blue;
+	bitfield_t transp;
+	uint32_t nonstd;
+	uint32_t activate;
+	uint32_t height;
+	uint32_t width;
+	uint32_t accel_flags;
+	uint32_t pixclock;
+	uint32_t left_margin;
+	uint32_t right_margin;
+	uint32_t upper_margin;
+	uint32_t lower_margin;
+	uint32_t hsync_len;
+	uint32_t vsync_len;
+	uint32_t sync;
+	uint32_t vmode;
+	uint32_t rotate;
+	uint32_t colorspace;
+	uint32_t reserved[4];
+} varinfo_t;
+
+typedef struct {
+	char id[16];
+	unsigned long smem_start;
+	uint32_t smem_len;
+	uint32_t type;
+	uint32_t type_aux;
+	uint32_t visual;
+	uint16_t xpanstep;
+	uint16_t ypanstep;
+	uint16_t ywrapstep;
+	uint32_t line_length;
+	unsigned long mmio_start;
+	uint32_t mmio_len;
+	uint32_t accel;
+	uint16_t capabilities;
+	uint16_t reserved[2];
+} fixinfo_t;
+
+#define FB_VISUAL_TRUECOLOR 2
+#define FB_TYPE_PACKED_PIXELS 0
 
 volatile struct limine_framebuffer_request fb_liminereq = {
 	.id = LIMINE_FRAMEBUFFER_REQUEST,
 	.revision = 0
 };
+
+static size_t count;
+static struct limine_framebuffer **fbs;
+static fixinfo_t *fixinfos;
+static varinfo_t *varinfos;
+
+static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flags, size_t *readc) {
+	if (minor >= count)
+		return ENODEV;
+
+	uintmax_t end = fbs[minor]->pitch * fbs[minor]->height;
+	*readc = 0;
+
+	if (offset >= end)
+		return 0;
+
+	if(size + offset > end)
+		size = end - offset;
+
+	memcpy(buffer, (void *)((uintptr_t)fbs[minor]->address + offset), size);
+	*readc = size;
+
+	return 0;
+}
+
+static int write(int minor, void *buffer, size_t size, uintmax_t offset, int flags, size_t *writec) {
+	if (minor >= count)
+		return ENODEV;
+
+	uintmax_t end = fbs[minor]->pitch * fbs[minor]->height;
+	*writec = 0;
+
+	if (offset >= end)
+		return 0;
+
+	if(size + offset > end)
+		size = end - offset;
+
+	memcpy((void *)((uintptr_t)fbs[minor]->address + offset), buffer, size);
+	*writec = size;
+
+	return 0;
+}
+
+static int mmap(int minor, void *addr, uintmax_t offset, int flags) {
+	if (minor >= count)
+		return ENODEV;
+
+	uintmax_t end = fbs[minor]->pitch * fbs[minor]->height;
+	__assert(offset < end);
+
+	void *paddr = NULL;
+
+	if (flags & V_FFLAGS_SHARED) {
+		// make sure offset is ALWAYS page aligned when doing a shared mapping
+		__assert((offset % PAGE_SIZE) == 0);
+		return arch_mmu_map(_cpu()->vmmctx->pagetable, FROM_HHDM((void *)((uintptr_t)fbs[minor]->address + offset)), addr, vnodeflagstommuflags(flags)) ? 0 : ENOMEM;
+	} else {
+		size_t size = offset + PAGE_SIZE < end ? PAGE_SIZE : end - offset;
+		paddr = pmm_alloc(1, PMM_SECTION_DEFAULT);
+		if (paddr == NULL)
+			return ENOMEM;
+
+		memcpy(MAKE_HHDM(paddr), (void *)((uintptr_t)fbs[minor]->address + offset), size);
+
+		if (arch_mmu_map(_cpu()->vmmctx->pagetable, paddr, addr, vnodeflagstommuflags(flags)) == false) {
+			pmm_free(paddr, 1);
+			return ENOMEM;
+		}
+
+		return 0;
+	}
+}
+
+static int munmap(int minor, void *addr, uintmax_t offset, int flags) {
+	void *phys = arch_mmu_getphysical(_cpu()->vmmctx->pagetable, addr);
+	arch_mmu_unmap(_cpu()->vmmctx->pagetable, addr);
+	if ((flags & V_FFLAGS_SHARED) == 0) {
+		pmm_free(phys, 1);
+	}
+
+	return 0;
+}
+
+#define FBIOGET_VSCREENINFO	0x4600
+#define FBIOPUT_VSCREENINFO	0x4601
+#define FBIOGET_FSCREENINFO	0x4602
+#define FBIOBLANK		0x4611
+
+static int ioctl(int minor, unsigned long request, void *arg, int *result){
+        if(minor >= count)
+                return ENODEV;
+
+        switch (request) {
+		case FBIOGET_FSCREENINFO:
+			*(fixinfo_t *)arg = fixinfos[minor];
+			break;
+		case FBIOGET_VSCREENINFO:
+			*(varinfo_t *)arg = varinfos[minor];
+			break;
+		default:
+			return ENOTTY;
+        }
+
+        return 0;
+}
+
+static devops_t ops = {
+	.read = read,
+	.write = write,
+	.mmap = mmap,
+	.munmap = munmap,
+	.ioctl = ioctl
+};
+
+void fb_init() {
+	if (fb_liminereq.response == NULL || fb_liminereq.response->framebuffer_count == 0) {
+		printf("fb: no framebuffer devices\n");
+		return;
+	}
+
+	fbs = fb_liminereq.response->framebuffers;
+	count = fb_liminereq.response->framebuffer_count;
+	printf("fb: %d framebuffer device%c\n", count, count > 1 ? 's' : ' ');
+
+	fixinfos = alloc(count * sizeof(fixinfo_t));
+	varinfos = alloc(count * sizeof(varinfo_t));
+	__assert(fixinfos && varinfos);
+
+	for (int i = 0; i < count; ++i) {
+		struct limine_framebuffer* fb = fbs[i];
+
+		varinfo_t* vi = &varinfos[i];
+		vi->xres = fb->width;
+		vi->yres = fb->height;
+		vi->xres_virtual = fb->width;
+		vi->yres_virtual = fb->height;
+		vi->bits_per_pixel = fb->bpp;
+		vi->red.msb_right = 1;
+		vi->green.msb_right = 1;
+		vi->blue.msb_right = 1;
+		vi->transp.msb_right = 1;
+		vi->red.offset = fb->red_mask_shift;
+		vi->red.length = fb->red_mask_size;
+		vi->blue.offset = fb->blue_mask_shift;
+		vi->blue.length = fb->blue_mask_size;
+		vi->green.offset = fb->green_mask_shift;
+		vi->green.length = fb->green_mask_size;
+		vi->height = -1;
+		vi->width = -1;
+
+		fixinfo_t* fi = &fixinfos[i];
+		strcpy(fi->id, "LIMINE FB");
+		fi->smem_len = fb->pitch * fb->height;
+		fi->type = FB_TYPE_PACKED_PIXELS;
+		fi->visual = FB_VISUAL_TRUECOLOR;
+		fi->line_length = fb->pitch;
+		fi->mmio_len = fb->pitch * fb->height;
+
+		char name[6];
+		snprintf(name, 6, "fb%d", i);
+
+		__assert(devfs_register(&ops, name, V_TYPE_CHDEV, DEV_MAJOR_FB, i, 0644) == 0);
+
+		printf("%s: %dx%d %d bpp\n", name, fb->width, fb->height, fb->bpp);
+	}
+}