efi/gop: Add an option to list out the available GOP modes

Add video=efifb:list option to list the modes that are available.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200518190716.751506-20-nivedita@alum.mit.eduSigned-off-by: Ard Biesheuvel <ardb@kernel.org>

Documentation/fb/efifb.rst

@@ -63,4 +63,9 @@ auto
         with the highest resolution, it will choose one with the highest color
         depth.
 
+list
+        The EFI stub will list out all the display modes that are available. A
+        specific mode can then be chosen using one of the above options for the
+        next boot.
+
 Edgar Hucek <gimli@dark-green.com>

drivers/firmware/efi/libstub/efi-stub-helper.c

@@ -463,3 +463,38 @@ efi_status_t efi_load_initrd(efi_loaded_image_t *image,
 
 	return status;
 }
+
+efi_status_t efi_wait_for_key(unsigned long usec, efi_input_key_t *key)
+{
+	efi_event_t events[2], timer;
+	unsigned long index;
+	efi_simple_text_input_protocol_t *con_in;
+	efi_status_t status;
+
+	con_in = efi_table_attr(efi_system_table, con_in);
+	if (!con_in)
+		return EFI_UNSUPPORTED;
+	efi_set_event_at(events, 0, efi_table_attr(con_in, wait_for_key));
+
+	status = efi_bs_call(create_event, EFI_EVT_TIMER, 0, NULL, NULL, &timer);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	status = efi_bs_call(set_timer, timer, EfiTimerRelative,
+			     EFI_100NSEC_PER_USEC * usec);
+	if (status != EFI_SUCCESS)
+		return status;
+	efi_set_event_at(events, 1, timer);
+
+	status = efi_bs_call(wait_for_event, 2, events, &index);
+	if (status == EFI_SUCCESS) {
+		if (index == 0)
+			status = efi_call_proto(con_in, read_keystroke, key);
+		else
+			status = EFI_TIMEOUT;
+	}
+
+	efi_bs_call(close_event, timer);
+
+	return status;
+}

drivers/firmware/efi/libstub/efistub.h

@@ -323,6 +323,8 @@ union efi_simple_text_input_protocol {
 	} mixed_mode;
 };
 
+efi_status_t efi_wait_for_key(unsigned long usec, efi_input_key_t *key);
+
 union efi_simple_text_output_protocol {
 	struct {
 		void *reset;

drivers/firmware/efi/libstub/gop.c

@@ -19,7 +19,8 @@ enum efi_cmdline_option {
 	EFI_CMDLINE_NONE,
 	EFI_CMDLINE_MODE_NUM,
 	EFI_CMDLINE_RES,
-	EFI_CMDLINE_AUTO
+	EFI_CMDLINE_AUTO,
+	EFI_CMDLINE_LIST
 };
 
 static struct {
@@ -100,6 +101,19 @@ static bool parse_auto(char *option, char **next)
 	return true;
 }
 
+static bool parse_list(char *option, char **next)
+{
+	if (!strstarts(option, "list"))
+		return false;
+	option += strlen("list");
+	if (*option && *option++ != ',')
+		return false;
+	cmdline.option = EFI_CMDLINE_LIST;
+
+	*next = option;
+	return true;
+}
+
 void efi_parse_option_graphics(char *option)
 {
 	while (*option) {
@@ -109,6 +123,8 @@ void efi_parse_option_graphics(char *option)
 			continue;
 		if (parse_auto(option, &option))
 			continue;
+		if (parse_list(option, &option))
+			continue;
 
 		while (*option && *option++ != ',')
 			;
@@ -290,6 +306,82 @@ static u32 choose_mode_auto(efi_graphics_output_protocol_t *gop)
 	return best_mode;
 }
 
+static u32 choose_mode_list(efi_graphics_output_protocol_t *gop)
+{
+	efi_status_t status;
+
+	efi_graphics_output_protocol_mode_t *mode;
+	efi_graphics_output_mode_info_t *info;
+	unsigned long info_size;
+
+	u32 max_mode, cur_mode;
+	int pf;
+	efi_pixel_bitmask_t pi;
+	u32 m, w, h;
+	u8 d;
+	const char *dstr;
+	bool valid;
+	efi_input_key_t key;
+
+	mode = efi_table_attr(gop, mode);
+
+	cur_mode = efi_table_attr(mode, mode);
+	max_mode = efi_table_attr(mode, max_mode);
+
+	efi_printk("Available graphics modes are 0-%u\n", max_mode-1);
+	efi_puts("  * = current mode\n"
+		 "  - = unusable mode\n");
+	for (m = 0; m < max_mode; m++) {
+		status = efi_call_proto(gop, query_mode, m,
+					&info_size, &info);
+		if (status != EFI_SUCCESS)
+			continue;
+
+		pf = info->pixel_format;
+		pi = info->pixel_information;
+		w  = info->horizontal_resolution;
+		h  = info->vertical_resolution;
+
+		efi_bs_call(free_pool, info);
+
+		valid = !(pf == PIXEL_BLT_ONLY || pf >= PIXEL_FORMAT_MAX);
+		d = 0;
+		switch (pf) {
+		case PIXEL_RGB_RESERVED_8BIT_PER_COLOR:
+			dstr = "rgb";
+			break;
+		case PIXEL_BGR_RESERVED_8BIT_PER_COLOR:
+			dstr = "bgr";
+			break;
+		case PIXEL_BIT_MASK:
+			dstr = "";
+			d = pixel_bpp(pf, pi);
+			break;
+		case PIXEL_BLT_ONLY:
+			dstr = "blt";
+			break;
+		default:
+			dstr = "xxx";
+			break;
+		}
+
+		efi_printk("Mode %3u %c%c: Resolution %ux%u-%s%.0hhu\n",
+			   m,
+			   m == cur_mode ? '*' : ' ',
+			   !valid ? '-' : ' ',
+			   w, h, dstr, d);
+	}
+
+	efi_puts("\nPress any key to continue (or wait 10 seconds)\n");
+	status = efi_wait_for_key(10 * EFI_USEC_PER_SEC, &key);
+	if (status != EFI_SUCCESS && status != EFI_TIMEOUT) {
+		efi_err("Unable to read key, continuing in 10 seconds\n");
+		efi_bs_call(stall, 10 * EFI_USEC_PER_SEC);
+	}
+
+	return cur_mode;
+}
+
 static void set_mode(efi_graphics_output_protocol_t *gop)
 {
 	efi_graphics_output_protocol_mode_t *mode;
@@ -305,6 +397,9 @@ static void set_mode(efi_graphics_output_protocol_t *gop)
 	case EFI_CMDLINE_AUTO:
 		new_mode = choose_mode_auto(gop);
 		break;
+	case EFI_CMDLINE_LIST:
+		new_mode = choose_mode_list(gop);
+		break;
 	default:
 		return;
 	}

include/linux/efi.h

@@ -39,6 +39,7 @@
 #define EFI_WRITE_PROTECTED	( 8 | (1UL << (BITS_PER_LONG-1)))
 #define EFI_OUT_OF_RESOURCES	( 9 | (1UL << (BITS_PER_LONG-1)))
 #define EFI_NOT_FOUND		(14 | (1UL << (BITS_PER_LONG-1)))
+#define EFI_TIMEOUT		(18 | (1UL << (BITS_PER_LONG-1)))
 #define EFI_ABORTED		(21 | (1UL << (BITS_PER_LONG-1)))
 #define EFI_SECURITY_VIOLATION	(26 | (1UL << (BITS_PER_LONG-1)))