drivers/video/fbdev/udlfb.c

Source file repositories/reference/linux-study-clean/drivers/video/fbdev/udlfb.c

File Facts

System
Linux kernel
Corpus path
drivers/video/fbdev/udlfb.c
Extension
.c
Size
52442 bytes
Lines
1991
Domain
Driver Families
Bucket
drivers/video
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct dlfb_deferred_free {
	struct list_head list;
	void *mem;
};

static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info, u32 new_len);

/* dlfb keeps a list of urbs for efficient bulk transfers */
static void dlfb_urb_completion(struct urb *urb);
static struct urb *dlfb_get_urb(struct dlfb_data *dlfb);
static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb * urb, size_t len);
static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size);
static void dlfb_free_urb_list(struct dlfb_data *dlfb);

/*
 * All DisplayLink bulk operations start with 0xAF, followed by specific code
 * All operations are written to buffers which then later get sent to device
 */
static char *dlfb_set_register(char *buf, u8 reg, u8 val)
{
	*buf++ = 0xAF;
	*buf++ = 0x20;
	*buf++ = reg;
	*buf++ = val;
	return buf;
}

static char *dlfb_vidreg_lock(char *buf)
{
	return dlfb_set_register(buf, 0xFF, 0x00);
}

static char *dlfb_vidreg_unlock(char *buf)
{
	return dlfb_set_register(buf, 0xFF, 0xFF);
}

/*
 * Map FB_BLANK_* to DisplayLink register
 * DLReg FB_BLANK_*
 * ----- -----------------------------
 *  0x00 FB_BLANK_UNBLANK (0)
 *  0x01 FB_BLANK (1)
 *  0x03 FB_BLANK_VSYNC_SUSPEND (2)
 *  0x05 FB_BLANK_HSYNC_SUSPEND (3)
 *  0x07 FB_BLANK_POWERDOWN (4) Note: requires modeset to come back
 */
static char *dlfb_blanking(char *buf, int fb_blank)
{
	u8 reg;

	switch (fb_blank) {
	case FB_BLANK_POWERDOWN:
		reg = 0x07;
		break;
	case FB_BLANK_HSYNC_SUSPEND:
		reg = 0x05;
		break;
	case FB_BLANK_VSYNC_SUSPEND:
		reg = 0x03;
		break;
	case FB_BLANK_NORMAL:
		reg = 0x01;
		break;
	default:
		reg = 0x00;
	}

	buf = dlfb_set_register(buf, 0x1F, reg);

	return buf;
}

static char *dlfb_set_color_depth(char *buf, u8 selection)
{
	return dlfb_set_register(buf, 0x00, selection);
}

static char *dlfb_set_base16bpp(char *wrptr, u32 base)
{
	/* the base pointer is 16 bits wide, 0x20 is hi byte. */
	wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
	wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
	return dlfb_set_register(wrptr, 0x22, base);
}

/*
 * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
 * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
 */

Annotation

Implementation Notes