[coreboot-gerrit] Patch set updated for coreboot: chromeos: Implement locating and decoding wifi sar data from VPD

[Robbie Zhang (robbie.zhang@intel.com)]

Robbie Zhang (robbie.zhang at intel.com) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/17958

-gerrit

commit a3325c8da722741f2a2dfb3c98e196fe01036a60
Author: Robbie Zhang <robbie.zhang at intel.com>
Date:   Fri Dec 23 11:43:07 2016 -0800

    chromeos: Implement locating and decoding wifi sar data from VPD
    
    A VPD entry "wifi_sar" needs to be created which contains a heximal
    encoded string in length of 40 bytes. wifi_sar_limits() function
    retrieves and decodes the data from the VPD entry, returning pointer
    to an instance of the structure (array of 40 bytes (u8)), which
    would later be consumed by platform code needing this data.
    
    BUG=chrome-os-partner:60821
    TEST=Build and boot lars and reef
    
    Change-Id: I923b58a63dc1f8a7fdd685cf1c618b2fdf4e7061
    Signed-off-by: Robbie Zhang <robbie.zhang at intel.com>
---
 src/include/sar.h                           | 28 ++++++++++
 src/vendorcode/google/chromeos/Makefile.inc |  1 +
 src/vendorcode/google/chromeos/cros_vpd.h   |  1 +
 src/vendorcode/google/chromeos/sar.c        | 82 +++++++++++++++++++++++++++++
 4 files changed, 112 insertions(+)

diff --git a/src/include/sar.h b/src/include/sar.h
new file mode 100644
index 0000000..32e83ec
--- /dev/null
+++ b/src/include/sar.h
@@ -0,0 +1,28 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2016 Intel Corp.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#ifndef _SAR_H_
+#define _SAR_H_
+
+#include <stdint.h>
+
+/* Wifi SAR limit table structure */
+struct wifi_sar_limit_t{
+	uint8_t sar_limit[40]; /* Total 4 SAR limit sets, each has 10 bytes */
+};
+
+/* Retrieve the SAR limits data from VPD and decode it */
+void wifi_sar_limits(struct wifi_sar_limit_t *sar_limits);
+
+#endif /* _SAR_H_ */
diff --git a/src/vendorcode/google/chromeos/Makefile.inc b/src/vendorcode/google/chromeos/Makefile.inc
index e84eb3d..878b068 100644
--- a/src/vendorcode/google/chromeos/Makefile.inc
+++ b/src/vendorcode/google/chromeos/Makefile.inc
@@ -25,6 +25,7 @@ ramstage-$(CONFIG_CHROMEOS_RAMOOPS) += ramoops.c
 romstage-y += vpd_decode.c
 ramstage-y += vpd_decode.c cros_vpd.c vpd_mac.c vpd_serialno.c vpd_calibration.c
 ramstage-$(CONFIG_HAVE_REGULATORY_DOMAIN) += wrdd.c
+ramstage-$(CONFIG_USE_SAR) += sar.c
 ifeq ($(CONFIG_ARCH_MIPS),)
 bootblock-y += watchdog.c
 ramstage-y += watchdog.c
diff --git a/src/vendorcode/google/chromeos/cros_vpd.h b/src/vendorcode/google/chromeos/cros_vpd.h
index 96ca8af..1fa56a4 100644
--- a/src/vendorcode/google/chromeos/cros_vpd.h
+++ b/src/vendorcode/google/chromeos/cros_vpd.h
@@ -8,6 +8,7 @@
 #define __CROS_VPD_H__
 
 #define CROS_VPD_REGION_NAME "region"
+#define CROS_VPD_WIFI_SAR_NAME "wifi_sar"
 
 /*
  * Reads VPD string value by key.
diff --git a/src/vendorcode/google/chromeos/sar.c b/src/vendorcode/google/chromeos/sar.c
new file mode 100644
index 0000000..c5adbf1
--- /dev/null
+++ b/src/vendorcode/google/chromeos/sar.c
@@ -0,0 +1,82 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2016 Intel Corp.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include <console/console.h>
+#include <types.h>
+#include <string.h>
+#include <sar.h>
+#include "cros_vpd.h"
+
+/*
+ * Decode string representation of the SAR limits (a string of hex symbols)
+ * into binary. 'key_name' is the name of the VPD field, it's used if
+ * it is necessary to report an input data format problem.
+ */
+static void decode_sar_limit(struct wifi_sar_limit_t *sar_limits,
+		       const char *sar_limit_str,
+		       const char *key_name)
+{
+	int i;
+	size_t size = sizeof(struct wifi_sar_limit_t) / sizeof(uint8_t);
+
+	for (i = 0; i < size; i++) {
+		int j;
+		int n = 0;
+
+		for (j = 0; j < 2; j++) {
+			char c = sar_limit_str[i * 2 + j];
+			if (isxdigit(c)) {
+				if (isdigit(c))
+					c = c - '0';
+				else
+					c =  tolower(c) - 'a' + 10;
+			} else {
+				printk(BIOS_ERR, "%s: non hexadecimal symbol "
+					"%#2.2x in the VPD field %s:%s\n",
+					__func__, (uint8_t)c, key_name,
+					sar_limit_str);
+			}
+			n <<= 4;
+			n |= c;
+		}
+		sar_limits->sar_limit[i] = n;
+	}
+}
+
+/* Retrieve the wifi SAR limits from VPD and decode it */
+void wifi_sar_limits(struct wifi_sar_limit_t *sar_limits)
+{
+	const char *wifi_sar_limit_key = CROS_VPD_WIFI_SAR_NAME;
+	/*
+	 * cros_vpd_gets() reads in one less than size characters from the VPD
+	 * with a terminating null byte ('\0') stored as the last character into
+	 * the buffer, thus the increasing by 1 for buffer_size.
+	 */
+	const size_t buffer_size = (sizeof(struct wifi_sar_limit_t) /
+				    sizeof(uint8_t)) * 2 + 1;
+	char wifi_sar_limit_str[buffer_size];
+
+	/* Try to read the SAR limit entry from VPD */
+	if (!cros_vpd_gets(wifi_sar_limit_key, wifi_sar_limit_str,
+		ARRAY_SIZE(wifi_sar_limit_str))) {
+		printk(BIOS_DEBUG,
+			"Error: Could not locate '%s' in VPD\n",
+			wifi_sar_limit_key);
+		return;
+	}
+	printk(BIOS_ERR, "VPD wifi_sar = %s\n", wifi_sar_limit_str);
+
+	/* Decode the heximal encoded string to binary values */
+	decode_sar_limit(sar_limits, wifi_sar_limit_str, wifi_sar_limit_key);
+}