CBI: Read board info from EEPROM

This patch adds Cros Board Info APIs. It reads board info from EEPROM.
This patch sets CONFIG_CBI for Fizz to make it use CBI.

BUG=b:70294260
BRANCH=none
TEST=Read data from EEPROM.

Change-Id: I7eb4323188817d46b0450f1d65ac34d1b7e4e220
Reviewed-on: https://chromium-review.googlesource.com/707741
Commit-Ready: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

1 files changed, 127 insertions, 0 deletions

diff --git a/common/cbi.c b/common/cbi.c
new file mode 100644
index 0000000000..dce8475d81
--- /dev/null
+++ b/common/cbi.c
@@ -0,0 +1,127 @@
+/* Copyright 2018 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Cros Board Info
+ */
+
+#include "common.h"
+#include "console.h"
+#include "crc8.h"
+#include "cros_board_info.h"
+#include "i2c.h"
+#include "util.h"
+
+#define CPRINTS(format, args...) cprints(CC_SYSTEM, "CBI " format, ## args)
+
+static struct board_info bi;
+/* TODO: Init it to -1. On error (I2C or bad contents), retry a read and set it
+ * to enum ec_error_list if it still fails. The successive calls can be
+ * immediately returned with the cached error code. This will avoid attempting
+ * reads doomed to fail. */
+static int initialized;
+
+static uint8_t cbi_crc8(const struct board_info *bi)
+{
+	return crc8((uint8_t *)&bi->head.crc + 1, bi->head.total_size - 4);
+}
+
+/*
+ * Get board information from EEPROM
+ */
+static int read_board_info(void)
+{
+	uint8_t buf[256];
+	uint8_t offset;
+
+	if (initialized)
+		return EC_SUCCESS;
+
+	CPRINTS("Reading board info");
+
+	/* Read header */
+	offset = 0;
+	if (i2c_xfer(I2C_PORT_EEPROM, I2C_ADDR_EEPROM,
+		     &offset, 1, buf, sizeof(bi.head), I2C_XFER_SINGLE)) {
+		CPRINTS("Failed to read header");
+		return EC_ERROR_INVAL;
+	}
+	memcpy(&bi.head, buf, sizeof(bi.head));
+
+	/* Check magic */
+	if (memcmp(bi.head.magic, cbi_magic, sizeof(bi.head.magic))) {
+		CPRINTS("Bad magic");
+		return EC_ERROR_INVAL;
+	}
+
+	/* check version */
+	if (bi.head.major_version > CBI_VERSION_MAJOR) {
+		CPRINTS("Version mismatch");
+		return EC_ERROR_INVAL;
+	}
+
+	/* Check the data size. It's expected to support up to 64k but our
+	 * buffer has practical limitation. */
+	if (bi.head.total_size < sizeof(bi) ||
+			bi.head.total_size > sizeof(buf)) {
+		CPRINTS("Bad size: %d", bi.head.total_size);
+		return EC_ERROR_OVERFLOW;
+	}
+
+	/* Read the rest */
+	offset = sizeof(bi.head);
+	if (i2c_xfer(I2C_PORT_EEPROM, I2C_ADDR_EEPROM, &offset, 1,
+		     buf + sizeof(bi.head),
+		     bi.head.total_size - sizeof(bi.head),
+		     I2C_XFER_SINGLE)) {
+		CPRINTS("Failed to read body");
+		return EC_ERROR_INVAL;
+	}
+
+	/* Check CRC. This supports new fields unknown to this parser. */
+	if (cbi_crc8((struct board_info *)&buf) != bi.head.crc) {
+		CPRINTS("Bad CRC");
+		return EC_ERROR_INVAL;
+	}
+
+	/* Save only the data we understand. */
+	memcpy(&bi.head + 1, &buf[sizeof(bi.head)],
+	       sizeof(bi) - sizeof(bi.head));
+	/* If we're handling previous version, clear all new fields */
+
+	initialized = 1;
+
+	return EC_SUCCESS;
+}
+
+int cbi_get_board_version(uint32_t *version)
+{
+	if (read_board_info())
+		return EC_ERROR_UNKNOWN;
+	*version = bi.version;
+	return EC_SUCCESS;
+}
+
+int cbi_get_sku_id(uint32_t *sku_id)
+{
+	if (read_board_info())
+		return EC_ERROR_UNKNOWN;
+	*sku_id = bi.sku_id;
+	return EC_SUCCESS;
+}
+
+int cbi_get_oem_id(uint32_t *oem_id)
+{
+	if (read_board_info())
+		return EC_ERROR_UNKNOWN;
+	*oem_id = bi.oem_id;
+	return EC_SUCCESS;
+}
+
+int board_get_version(void)
+{
+	uint32_t version;
+	if (cbi_get_board_version(&version))
+		return -1;
+	return version;
+}