amd64: /video/b device, provided by grub

3 files changed, 96 insertions, 1 deletions

diff --git a/src/kernel/arch/amd64/driver/fsroot.c b/src/kernel/arch/amd64/driver/fsroot.c
index 2feaf67..e0f5e77 100644
--- a/src/kernel/arch/amd64/driver/fsroot.c
+++ b/src/kernel/arch/amd64/driver/fsroot.c
@@ -58,11 +58,13 @@ static int handle(struct vfs_request *req) {
 			switch (id) {
 				case HANDLE_ROOT: {
 					// TODO document directory read format
+					// TODO don't hardcode
 					const char src[] =
 						"vga\0"
 						"com1\0"
 						"ps2\0"
-						"ata/";
+						"ata/\0"
+						"video/";
 					return req_readcopy(req, src, sizeof src);
 				}
 				case HANDLE_VGA:
diff --git a/src/kernel/arch/amd64/driver/video.c b/src/kernel/arch/amd64/driver/video.c
new file mode 100644
index 0000000..8ace3d4
--- /dev/null
+++ b/src/kernel/arch/amd64/driver/video.c
@@ -0,0 +1,82 @@
+#include <camellia/fsutil.h>
+#include <camellia/errno.h>
+#include <kernel/arch/amd64/driver/video.h>
+#include <kernel/mem/virt.h>
+#include <kernel/panic.h>
+#include <kernel/vfs/request.h>
+
+static struct fb_info fb;
+
+enum {
+	H_ROOT,
+	H_FB,
+};
+
+/* stolen from fsroot.c, TODO shared copy? i guess? */
+static int req_readcopy(struct vfs_request *req, const void *buf, size_t len) {
+	if (!req->caller) return -1;
+	assert(req->type == VFSOP_READ);
+	fs_normslice(&req->offset, &req->output.len, len, false);
+	virt_cpy_to(
+			req->caller->pages, req->output.buf,
+			buf + req->offset, req->output.len);
+	/* read errors are ignored. TODO write docs */
+	return req->output.len;
+}
+
+static int handle(struct vfs_request *req) {
+	switch (req->type) {
+		case VFSOP_OPEN:
+			if (req->input.len == 1) {
+				return H_ROOT;
+			} else if (req->input.len == 2 && req->input.kern && req->input.buf_kern[1] == 'b') {
+				return H_FB;
+			} else {
+				return -1;
+			}
+
+		case VFSOP_READ:
+			if (req->id == H_ROOT) {
+				// TODO list available modes, e.g /640x480x24
+				const char src[] = "b";
+				return req_readcopy(req, src, sizeof src);
+			} else {
+				return req_readcopy(req, fb.b, fb.pitch * fb.height);
+			}
+
+		case VFSOP_WRITE:
+			if ((long)req->id != H_FB) {
+				return -1;
+			}
+			fs_normslice(&req->offset, &req->input.len, fb.pitch * fb.height, false);
+			if (!virt_cpy_from(req->caller->pages, fb.b + req->offset,
+					req->input.buf, req->input.len))
+			{
+				panic_invalid_state();
+				return -EFAULT;
+			}
+			return req->input.len;
+
+		default:
+			return -1;
+	}
+}
+
+static void accept(struct vfs_request *req) {
+	if (req->caller) {
+		vfsreq_finish_short(req, handle(req));
+	} else {
+		vfsreq_finish_short(req, -1);
+	}
+}
+
+static bool is_ready(struct vfs_backend *self) {
+	(void)self;
+	return true;
+}
+
+static struct vfs_backend backend = BACKEND_KERN(is_ready, accept);
+void video_init(struct fb_info fb_) {
+	fb = fb_;
+	vfs_mount_root_register("/video", &backend);
+}
diff --git a/src/kernel/arch/amd64/driver/video.h b/src/kernel/arch/amd64/driver/video.h
new file mode 100644
index 0000000..c1680c4
--- /dev/null
+++ b/src/kernel/arch/amd64/driver/video.h
@@ -0,0 +1,11 @@
+#pragma once
+#include <stdint.h>
+
+struct fb_info {
+	char *b;
+	uint32_t width, height;
+	uint32_t pitch; /* width in bytes of a single scanline */
+	uint8_t bpp;
+};
+
+void video_init(struct fb_info);