Initial version of crossystem.

host/lib/crossystem.c

+/* Copyright (c) 2011 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.
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "host_common.h"
+
+#include "crossystem.h"
+#include "utility.h"
+#include "vboot_common.h"
+
+// GPIO signal types

[vb, 2011/02/05 01:17:18]

A nit: do we use C++ comments in S sources?

[Randall Spangler, 2011/02/07 17:58:10]

Done.

+#define GPIO_SIGNAL_TYPE_RECOVERY 1
+#define GPIO_SIGNAL_TYPE_DEV 2
+#define GPIO_SIGNAL_TYPE_WP 3
+
+// CHSW bitflags
+#define CHSW_RECOVERY_BOOT     0x00000002

[vb, 2011/02/05 01:17:18]

haven't these flags been already defined somewhere else in the vboot space?

[Randall Spangler, 2011/02/07 17:58:10]

No, interestingly enough.  CHSW is currently provided via ACPI from H2C, and
vboot uses a different set of flags to LoadKernel() and LoadFirmware().

+#define CHSW_RECOVERY_EC_BOOT  0x00000004
+#define CHSW_DEV_BOOT          0x00000020
+#define CHSW_WP_BOOT           0x00000200
+
+// Base name for ACPI files
+#define ACPI_BASE_PATH "/sys/devices/platform/chromeos_acpi"
+// Paths for frequently used ACPI files
+#define ACPI_CHNV_PATH ACPI_BASE_PATH "/CHNV"
+#define ACPI_CHSW_PATH ACPI_BASE_PATH "/CHSW"
+#define ACPI_GPIO_PATH ACPI_BASE_PATH "/GPIO"
+
+// Base name for GPIO files
+#define GPIO_BASE_PATH "/sys/class/gpio"
+#define GPIO_EXPORT_PATH GPIO_BASE_PATH "/export"
+
+/* Read a string from a file.  Passed the destination, dest size, and
+ * filename to read.
+ *
+ * Returns the destination, or NULL if error. */
+char* ReadFileString(char* dest, int size, const char* filename) {
+  char* got;
+  FILE* f;
+
+  f = fopen(filename, "rt");
+  if (!f)
+    return NULL;
+
+  got = fgets(dest, size, f);

[vb, 2011/02/05 01:17:18]

what if fgets() fails?

[Randall Spangler, 2011/02/07 17:58:10]

got() returns NULL, which is passed through by ReadFileString() to mean error.

+  fclose(f);
+  return got;
+}
+
+
+/* Read an integer from a file.
+ *
+ * Returns the parsed integer, or -1 if error. */
+int ReadFileInt(const char* filename) {
+  char buf[64];
+  int value;
+  char* e = NULL;
+
+  if (!ReadFileString(buf, sizeof(buf), filename))
+    return -1;
+
+  // Convert to integer.  Allow characters after the int ("123 blah").
+  value = strtol(buf, &e, 0);
+  if (!*buf || e == buf)

[vb, 2011/02/05 01:17:18]

what's !*buf checking?

[Randall Spangler, 2011/02/07 17:58:10]

Empty string, but in that case, ReadFileString() would have failed.  Removed.

+    return -1;
+
+  return value;
+}
+
+
+/* Check if a bit is set in a file which contains an integer.
+ *
+ * Returns 1 if the bit is set, 0 if clear, or -1 if error. */
+int ReadFileBit(const char* filename, int bitmask) {
+  int value = ReadFileInt(filename);
+  if (value == -1)
+    return -1;
+  else return (value & bitmask ? 1 : 0);
+}
+
+
+/* Read a GPIO of the specified signal type (see ACPI GPIO SignalType).
+ *
+ * Returns 1 if the signal is asserted, 0 if not asserted, or -1 if error. */
+int ReadGpio(int signal_type) {
+  char name[128];
+  int index = 0;
+  int gpio_type;
+  int active_high;
+  int controller_offset;
+  char controller_name[128];
+  int value;
+
+  // Scan GPIO.* to find a matching signal type
+  for (index = 0; ; index++) {
+    snprintf(name, sizeof(name), "%s.%d/GPIO.0", ACPI_GPIO_PATH, index);
+    gpio_type = ReadFileInt(name);
+    if (gpio_type == signal_type)
+      break;
+    else if (gpio_type == -1)
+      return -1;  // Ran out of GPIOs before finding a match
+  }
+
+  // Read attributes and controller info for the GPIO
+  snprintf(name, sizeof(name), "%s.%d/GPIO.1", ACPI_GPIO_PATH, index);
+  active_high = ReadFileBit(name, 0x00000001);
+  snprintf(name, sizeof(name), "%s.%d/GPIO.2", ACPI_GPIO_PATH, index);
+  controller_offset = ReadFileInt(name);
+  if (active_high == -1 || controller_offset == -1)
+    return -1;  // Missing needed info
+
+  // We only support the NM10 for now
+  snprintf(name, sizeof(name), "%s.%d/GPIO.3", ACPI_GPIO_PATH, index);
+  if (!ReadFileString(controller_name, sizeof(controller_name), name))
+    return -1;
+  if (strcmp(controller_name, "NM10"))
+    return -1;
+
+  // Assume the NM10 has offset 192
+  /* TODO: should really check gpiochipNNN/label to see if it's the
+   * address we expect for the NM10, and then read the offset from
+   * gpiochipNNN/base. */
+  controller_offset += 192;
+
+  // Try reading the GPIO value
+  snprintf(name, sizeof(name), "%s/gpio%d/value",
+           GPIO_BASE_PATH, controller_offset);
+  value = ReadFileInt(name);
+
+  if (value == -1) {
+    // Try exporting the GPIO
+    FILE* f = fopen(GPIO_EXPORT_PATH, "wt");
+    if (!f)
+      return -1;
+    fprintf(f, "%d", controller_offset);
+    fclose(f);
+
+    // Try re-reading the GPIO value
+    value = ReadFileInt(name);
+  }
+
+  if (value == -1)
+    return -1;
+
+  // Compare the GPIO value with the active value
+  return (value == active_high ? 1 : 0);
+}
+
+
+/* Read a system property integer.
+ *
+ * Returns the property value, or -1 if error. */
+int VbGetSystemPropertyInt(const char* name) {
+
+  if (!strcasecmp(name,"devsw_cur")) {
+    return ReadGpio(GPIO_SIGNAL_TYPE_DEV);
+  } else if (!strcasecmp(name,"devsw_boot")) {
+    return ReadFileBit(ACPI_CHSW_PATH, CHSW_DEV_BOOT);
+  } else if (!strcasecmp(name,"recoverysw_cur")) {
+    return ReadGpio(GPIO_SIGNAL_TYPE_RECOVERY);
+  } else if (!strcasecmp(name,"recoverysw_boot")) {
+    return ReadFileBit(ACPI_CHSW_PATH, CHSW_RECOVERY_BOOT);
+  } else if (!strcasecmp(name,"recoverysw_ec_boot")) {
+    return ReadFileBit(ACPI_CHSW_PATH, CHSW_RECOVERY_EC_BOOT);
+  } else if (!strcasecmp(name,"wpsw_cur")) {
+    return ReadGpio(GPIO_SIGNAL_TYPE_WP);
+  } else if (!strcasecmp(name,"wpsw_boot")) {
+    return ReadFileBit(ACPI_CHSW_PATH, CHSW_WP_BOOT);
+  } else
+    return -1;  // Unknown property
+
+  // TODO: remaining properties from spec
+}
+
+
+/* Read a system property string into a destination buffer of the specified
+ * size.
+ *
+ * Returns the passed buffer, or NULL if error. */
+const char* VbGetSystemPropertyString(const char* name, char* dest, int size) {
+
+  if (!strcasecmp(name,"hwid")) {
+    return ReadFileString(dest, size, ACPI_BASE_PATH "/HWID");
+  } else if (!strcasecmp(name,"fwid")) {
+    return ReadFileString(dest, size, ACPI_BASE_PATH "/FWID");
+  } else if (!strcasecmp(name,"ro_fwid")) {
+    return ReadFileString(dest, size, ACPI_BASE_PATH "/FRID");
+  } else
+    return NULL;  // Unknown property
+
+  // TODO: remaining properties from spec
+}
+
+
+/* Set a system property integer.
+ *
+ * Returns 0 if success, -1 if error. */
+int VbSetSystemPropertyInt(const char* name, int value) {
+
+  // TODO: support setting
+  return -1;
+}
+
+
+/* Set a system property string.
+ *
+ * Returns 0 if success, -1 if error. */
+int VbSetSystemPropertyString(const char* name, const char* value) {
+
+  // TODO: support setting
+  return -1;
+}