{commonlib, libpayload}: Add "has_external_display" in coreboot table

This patch introduces a new coreboot table entry named
"has_external_display" to understand if external display is attached.

This information is useful to prevent graceful shutdown by payload
when the LID is closed but an external display is present.

This piece of the information will be gathered by coreboot and passed
into the payload using this new entry aka external_display because
payload (i.e., deptcharge) doesn't have any other way to determine
if external display is available.

BUG=b:299137940
TEST=Able to build and boot google/rex.

w/o this patch:

LID closed and external display attached (HDMI) in developer mode
  (GBB 0x39):

> System is powered off by depthcharge

w/ this patch:

LID closed and external display attached (HDMI) in developer mode
  (GBB 0x39):

> Booted to OS and device is alive/usable

Change-Id: I0fa7eee4c5a50371a7a66c6ca1ac2c7d046d010b
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77796
Reviewed-by: Eric Lai <ericllai@google.com>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

4 files changed, 34 insertions, 1 deletions

diff --git a/payloads/libpayload/include/coreboot_tables.h b/payloads/libpayload/include/coreboot_tables.h
index 4502e34484..5c3f0c47ec 100644
--- a/payloads/libpayload/include/coreboot_tables.h
+++ b/payloads/libpayload/include/coreboot_tables.h
@@ -220,6 +220,11 @@ enum cb_fb_orientation {
 	CB_FB_ORIENTATION_RIGHT_UP = 3,
 };
 
+struct cb_framebuffer_flags {
+	u8 has_external_display : 1;
+	u8 reserved : 7;
+};
+
 struct cb_framebuffer {
 	u32 tag;
 	u32 size;
@@ -238,6 +243,8 @@ struct cb_framebuffer {
 	u8 reserved_mask_pos;
 	u8 reserved_mask_size;
 	u8 orientation;
+	struct cb_framebuffer_flags flags;
+	u8 pad;
 };
 
 #define CB_GPIO_ACTIVE_LOW 0
diff --git a/src/commonlib/include/commonlib/coreboot_tables.h b/src/commonlib/include/commonlib/coreboot_tables.h
index d77c5eb26f..94985b1567 100644
--- a/src/commonlib/include/commonlib/coreboot_tables.h
+++ b/src/commonlib/include/commonlib/coreboot_tables.h
@@ -275,6 +275,11 @@ enum lb_fb_orientation {
 	LB_FB_ORIENTATION_RIGHT_UP = 3,
 };
 
+struct lb_framebuffer_flags {
+	uint8_t has_external_display : 1;
+	uint8_t reserved : 7;
+};
+
 struct lb_framebuffer {
 	uint32_t tag;
 	uint32_t size;
@@ -293,7 +298,8 @@ struct lb_framebuffer {
 	uint8_t reserved_mask_pos;
 	uint8_t reserved_mask_size;
 	uint8_t orientation;
-	uint8_t pad[2];
+	struct lb_framebuffer_flags flags;
+	uint8_t pad;
 };
 
 struct lb_gpio {
diff --git a/src/drivers/intel/fsp2_0/graphics.c b/src/drivers/intel/fsp2_0/graphics.c
index 6514209d04..a98f3bbba2 100644
--- a/src/drivers/intel/fsp2_0/graphics.c
+++ b/src/drivers/intel/fsp2_0/graphics.c
@@ -54,6 +54,13 @@ enum fw_splash_screen_status {
 	FW_SPLASH_SCREEN_ENABLED,
 };
 
+/* Check and report if an external display is attached */
+__weak int fsp_soc_report_external_display(void)
+{
+	/* Default implementation, on-board display enabled */
+	return 0;
+}
+
 /*
  * Update elog with Firmware Splash Screen related information
  * based on enum fw_splash_screen_status.
@@ -123,6 +130,9 @@ void fsp_report_framebuffer_info(const uintptr_t framebuffer_bar,
 		.reserved_mask_pos   = fbinfo->rsvd.pos,
 		.reserved_mask_size  = fbinfo->rsvd.size,
 		.orientation         = orientation,
+		.flags = {
+			.has_external_display = fsp_soc_report_external_display(),
+		},
 	};
 
 	fb_add_framebuffer_info_ex(&fb);
diff --git a/src/drivers/intel/fsp2_0/include/fsp/graphics.h b/src/drivers/intel/fsp2_0/include/fsp/graphics.h
index dfd7b4e65b..a5f781f87f 100644
--- a/src/drivers/intel/fsp2_0/include/fsp/graphics.h
+++ b/src/drivers/intel/fsp2_0/include/fsp/graphics.h
@@ -14,4 +14,14 @@
 void fsp_report_framebuffer_info(const uintptr_t framebuffer_bar,
 				 enum lb_fb_orientation orientation);
 
+/* SoC Overrides */
+/*
+ * Check and report if an external display is attached
+ *
+ * Possible return values:
+ * 1 - An external device is attached.
+ * 0 - On-board display alone.
+ */
+int fsp_soc_report_external_display(void);
+
 #endif /* _FSP2_0_GRAPHICS_H_ */