libpayload: Add coreboot boot mode table

This commit adds a new coreboot table, CB_TAG_BOOT_MODE, to pass
platform boot mode information to the payload.

The new table defines flags for low-battery mode and off-mode charging,
which are essential for a payload to properly initialize the charger
driver.

The cb_parse_boot_mode function is added to read this information, and
the sysinfo_t structure is updated to store the parsed boot mode data.

This ensures that the payload can accurately determine the system's
power state at boot and payload operations are also in sync with the
boot firmware.

The following scenarios were tested and verified:

Scenario 1: Low-battery, no charger
 - coreboot detects the low-battery state and performs an immediate
   shutdown after displaying the low-battery splash screen.

Scenario 2: Low-battery, charger attached
 - coreboot detects the low-battery state but continues booting because
   a charger is present. The payload receives the low-battery
   information (using the same source as coreboot) and correctly
   initiates the charging process.

Scenario 3: Off-mode charging
 - The system boots directly from an S5 state due to a charger being
   plugged in. coreboot detects the off-mode state, skips the firmware
   splash screen, and hands off control to the payload, which then
   starts charging.

Scenario 4: Normal boot
 - The system boots without any low-battery or off-mode conditions.
   coreboot and the payload both detect a normal boot (using the same
   information), bypass charging initialization, and proceed to boot the
   operating system.

TEST=Able to build and boot on google/quenbi device and verify the boot
mode flag is correctly passed.

Change-Id: Iec25c6fdfcdc5ea7c397d2430ac7b545e1e068f2
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/89015
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

payloads/libpayload/include/coreboot_tables.h

@@ -90,6 +90,7 @@ enum {
 	CB_TAG_OPTION_ENUM		= 0x00ca,
 	CB_TAG_OPTION_DEFAULTS		= 0x00cb,
 	CB_TAG_OPTION_CHECKSUM		= 0x00cc,
+	CB_TAG_BOOT_MODE		= 0x00cd,
 };
 
 typedef __aligned(4) uint64_t cb_uint64_t;
@@ -443,6 +444,23 @@ struct cb_acpi_rsdp {
 	cb_uint64_t rsdp_pointer; /* Address of the ACPI RSDP */
 };
 
+enum boot_mode_t {
+	CB_BOOT_MODE_NORMAL,
+	CB_BOOT_MODE_LOW_BATTERY,
+	CB_BOOT_MODE_OFFMODE_CHARGING,
+};
+
+/*
+ * Boot Mode: Pass the platform boot mode information to payload about
+ * booting in low-battery mode or off-mode charging. These information
+ * is useful for payload to implement charger driver.
+ */
+struct cb_boot_mode {
+	uint32_t tag;
+	uint32_t size;
+
+	enum boot_mode_t boot_mode;
+};
 
 /* Helpful inlines */
 

payloads/libpayload/include/sysinfo.h

@@ -173,6 +173,7 @@ struct sysinfo_t {
 	/* pvmfw buffer location */
 	uintptr_t pvmfw;
 	uint32_t pvmfw_size;
+	enum boot_mode_t boot_mode;
 };
 
 extern struct sysinfo_t lib_sysinfo;

payloads/libpayload/libc/coreboot.c

@@ -285,6 +285,13 @@ static void cb_parse_pcie(void *ptr, struct sysinfo_t *info)
 	info->pcie_ctrl_base = pcie->ctrl_base;
 }
 
+static void cb_parse_boot_mode(void *ptr, struct sysinfo_t *info)
+{
+	const struct cb_boot_mode *mode = ptr;
+
+	info->boot_mode = mode->boot_mode;
+}
+
 static void cb_parse_rsdp(void *ptr, struct sysinfo_t *info)
 {
 	const struct cb_acpi_rsdp *cb_acpi_rsdp = ptr;
@@ -437,6 +444,9 @@ int cb_parse_header(void *addr, int len, struct sysinfo_t *info)
 		case CB_TAG_PCIE:
 			cb_parse_pcie(ptr, info);
 			break;
+		case CB_TAG_BOOT_MODE:
+			cb_parse_boot_mode(ptr, info);
+			break;
 		default:
 			cb_parse_arch_specific(rec, info);
 			break;