drivers,fb: make scrolling optional (default)

Framebuffer scrolling can be enabled/disabled either on boot time via 'fb_scroll' cmdline parameter or on runtime using set_fb_scroll(); Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
KernelTestFramework · Aug 23, 2023 · c351a82 · c351a82
1 parent 1da50f4
commit c351a82
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Showing 4 changed files with 24 additions and 3 deletions.
diff --git a/common/cmdline.c b/common/cmdline.c
@@ -70,6 +70,9 @@ string_cmd("com3", opt_com3);
 static char opt_com4[20];
 string_cmd("com4", opt_com4);
 
+bool opt_fb_scroll = true;
+bool_cmd("fb_scroll", opt_fb_scroll);
+
 const char *kernel_cmdline;
 
 void __text_init cmdline_parse(const char *cmdline) {

diff --git a/drivers/fb/fb.c b/drivers/fb/fb.c
@@ -36,6 +36,7 @@ extern uint64_t fonts[];
 #define TEXT_AREA_FIRST_ROW (((LOGO_HEIGHT + FONT_SIZE) / FONT_SIZE) * FONT_SIZE)
 
 static bool has_fb = false;
+static bool scroll = false;
 
 static uint32_t width;
 static uint32_t height;
@@ -134,6 +135,7 @@ bool setup_framebuffer(void) {
     memset(video_memory, 0, buffer_size);
 
     register_console_callback(fb_console_write, video_memory);
+    scroll = opt_fb_scroll;
     return true;
 }
 
@@ -169,11 +171,19 @@ void draw_logo(void) {
     draw_line(0, LOGO_HEIGHT + 2, width, LOGO_HEIGHT + 2, FB_WHITE);
 }
 
-void scroll_up_line(void) {
+void set_fb_scroll(bool state) {
+    scroll = state;
+}
+
+static inline void scroll_up_line(void) {
     memmove(first_line_addr, first_line_addr + line_width,
             last_line_addr - first_line_addr);
 }
 
+static inline void clear_screen(void) {
+    memset(first_line_addr, 0, last_line_addr - first_line_addr);
+}
+
 void fb_write(void *fb_addr, const char *buf, size_t len, uint32_t color) {
     static uint32_t row = TEXT_AREA_FIRST_ROW, col = 0;
 
@@ -186,8 +196,14 @@ void fb_write(void *fb_addr, const char *buf, size_t len, uint32_t color) {
         }
 
         if ((row + FONT_SIZE) >= height) {
-            scroll_up_line();
-            row -= FONT_SIZE;
+            if (scroll) {
+                scroll_up_line();
+                row -= FONT_SIZE;
+            }
+            else {
+                clear_screen();
+                row = TEXT_AREA_FIRST_ROW;
+            }
             col = 0;
         }
 

diff --git a/include/cmdline.h b/include/cmdline.h
@@ -67,6 +67,7 @@ extern bool opt_hpet;
 extern bool opt_fpu;
 extern bool opt_qemu_console;
 extern bool opt_poweroff;
+extern bool opt_fb_scroll;
 
 extern const char *kernel_cmdline;
 

diff --git a/include/drivers/fb.h b/include/drivers/fb.h
@@ -36,5 +36,6 @@ extern void draw_line(uint32_t x1, uint32_t y1, uint32_t x2, uint32_t y2, uint32
 extern void draw_logo(void);
 extern void fb_write(void *fb_addr, const char *buf, size_t len, uint32_t color);
 extern bool setup_framebuffer(void);
+extern void set_fb_scroll(bool state);
 
 #endif /* KTF_DRV_FB_H */