mb/prodrive/hermes: Define board settings in EEPROM

Hermes has an EEPROM with firmware configuration data. Add definitions
to read and verify the `board settings` from the EEPROM. Subsequent
commits will hook up these EEPROM settings.

Change-Id: Id86632192ae53fd6b0e4df5b26b5a0a81e972818
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48806
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

2 files changed, 59 insertions, 0 deletions

diff --git a/src/mainboard/prodrive/hermes/eeprom.c b/src/mainboard/prodrive/hermes/eeprom.c
index d7ecdeca48..bff834036a 100644
--- a/src/mainboard/prodrive/hermes/eeprom.c
+++ b/src/mainboard/prodrive/hermes/eeprom.c
@@ -2,12 +2,17 @@
 
 #include <device/pci_ops.h>
 #include <console/console.h>
+#include <crc_byte.h>
 #include <device/smbus_host.h>
 #include <soc/intel/common/block/smbus/smbuslib.h>
+#include <types.h>
+
 #include "variants/baseboard/include/eeprom.h"
 
 #define I2C_ADDR_EEPROM 0x57
 
+#define EEPROM_OFFSET_BOARD_SETTINGS 0x1f00
+
 /*
  * Check Signature in EEPROM (M24C32-FMN6TP)
  * If signature is there we assume that that the content is valid
@@ -28,6 +33,41 @@ int check_signature(const size_t offset, const uint64_t signature)
 	return 0;
 }
 
+/*
+ * Read board settings from the EEPROM and verify their checksum.
+ * If checksum is valid, we assume the settings are sane as well.
+ */
+static bool get_board_settings_from_eeprom(struct eeprom_board_settings *board_cfg)
+{
+	if (read_write_config(board_cfg, EEPROM_OFFSET_BOARD_SETTINGS, 0, sizeof(*board_cfg))) {
+		printk(BIOS_ERR, "CFG EEPROM: Failed to read board settings\n");
+		return false;
+	}
+
+	const uint32_t crc =
+		CRC(&board_cfg->raw_settings, sizeof(board_cfg->raw_settings), crc32_byte);
+
+	if (crc != board_cfg->signature) {
+		printk(BIOS_ERR, "CFG EEPROM: Board settings have invalid checksum\n");
+		return false;
+	}
+	return true;
+}
+
+struct eeprom_board_settings *get_board_settings(void)
+{
+	static struct eeprom_board_settings board_cfg = {0};
+
+	/* Tri-state: -1: settings are invalid, 0: uninitialized, 1: settings are valid */
+	static int checked_valid = 0;
+
+	if (checked_valid == 0) {
+		const bool success = get_board_settings_from_eeprom(&board_cfg);
+		checked_valid = success ? 1 : -1;
+	}
+	return checked_valid > 0 ? &board_cfg : NULL;
+}
+
 /* Read data from offset and write it to offset in UPD */
 bool read_write_config(void *blob, size_t read_offset, size_t write_offset, size_t size)
 {
diff --git a/src/mainboard/prodrive/hermes/variants/baseboard/include/eeprom.h b/src/mainboard/prodrive/hermes/variants/baseboard/include/eeprom.h
index 95024b6ccd..d5a79cd9f9 100644
--- a/src/mainboard/prodrive/hermes/variants/baseboard/include/eeprom.h
+++ b/src/mainboard/prodrive/hermes/variants/baseboard/include/eeprom.h
@@ -18,6 +18,24 @@
 					.size = member_size(FSP_S_CONFIG, x)}
 #endif /* ENV_ROMSTAGE */
 
+__packed struct eeprom_board_settings {
+	uint32_t signature;
+	union {
+		struct {
+			uint8_t secureboot;
+			uint8_t primary_video;
+			uint8_t deep_sx_enabled;
+			uint8_t wake_on_usb;
+			uint8_t usb_powered_in_s5;
+			uint8_t power_state_after_g3;
+			uint8_t blue_rear_vref;
+			uint8_t internal_audio_connection;
+			uint8_t pxe_boot_capability;
+		};
+		uint8_t raw_settings[9];
+	};
+};
+
 typedef struct {
 	size_t offset;
 	size_t size;
@@ -25,3 +43,4 @@ typedef struct {
 
 bool read_write_config(void *blob, size_t read_offset, size_t write_offset, size_t size);
 int check_signature(const size_t offset, const uint64_t signature);
+struct eeprom_board_settings *get_board_settings(void);