crossystem: Change ReadFileInt to take an unsigned int pointer

Currently ReadFileInt assumes that an integer value read from a file
is never going to be "-1" and uses that value to indicate failure.
In particular for GPIO values that may be returned by the kernel it
is possible for them to be not simply 0 or 1 but instead a bit within
the GPIO status register that indicates the value.

The function semantics are changed to have the caller pass in the
variable to store the integer in, and use the return code explicitly
as a pass or fail condition.

This requires all the callers of ReadFileInt to be changed to use the
new scheme, and the x86 ReadGpio function is changed to normalize the
GPIO value that is read from the kernel instead of assuming it is
always 1 for active high values.

BUG=chrome-os-partner:32645
BRANCH=samus,auron
TEST=build for samus, check crossystem output and ensure that all
values are properly reported and that wpsw_cur is correct now.
Also tested to ensure no changes in output on: x86-alex, daisy,
peach_pit, lumpy, stumpy, nyan_big, nyan_blaze, rush_ryu, panther,
wolf, zako, auron, rambi, squawks, parrot_ivb, veyron_pinky

Change-Id: I824152eed5f96cf1faaa18ba31a01f4d346ad172
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/223009
Reviewed-by: Bill Richardson <wfrichar@chromium.org>

1 files changed, 13 insertions, 10 deletions

diff --git a/host/arch/arm/lib/crossystem_arch.c b/host/arch/arm/lib/crossystem_arch.c
index 92b61b4c..3864451c 100644
--- a/host/arch/arm/lib/crossystem_arch.c
+++ b/host/arch/arm/lib/crossystem_arch.c
@@ -68,12 +68,15 @@ const PlatformFamily platform_family_array[] = {
 
 static int FindEmmcDev(void) {
   int mmcblk;
+  unsigned value;
   char filename[FNAME_SIZE];
   for (mmcblk = 0; mmcblk < MAX_NMMCBLK; mmcblk++) {
     /* Get first non-removable mmc block device */
     snprintf(filename, sizeof(filename), "/sys/block/mmcblk%d/removable",
               mmcblk);
-    if (ReadFileInt(filename) == 0)
+    if (ReadFileInt(filename, &value) < 0)
+      continue;
+    if (value == 0)
       return mmcblk;
   }
   /* eMMC not found */
@@ -211,24 +214,23 @@ static char * ReadFdtPlatformFamily(void) {
 
 static int VbGetPlatformGpioStatus(const char* name) {
   char gpio_name[FNAME_SIZE];
-  int value;
+  unsigned value;
 
   snprintf(gpio_name, sizeof(gpio_name), "%s/%s/value",
            PLATFORM_DEV_PATH, name);
-  value = ReadFileInt(gpio_name);
+  if (ReadFileInt(gpio_name, &value) < 0)
+    return -1;
 
-  return value;
+  return (int)value;
 }
 
 static int VbGetGpioStatus(unsigned gpio_number) {
   char gpio_name[FNAME_SIZE];
-  int value;
+  unsigned value;
 
   snprintf(gpio_name, sizeof(gpio_name), "%s/gpio%d/value",
            GPIO_BASE_PATH, gpio_number);
-  value = ReadFileInt(gpio_name);
-
-  if (value == -1) {
+  if (ReadFileInt(gpio_name, &value) < 0) {
     /* Try exporting the GPIO */
     FILE* f = fopen(GPIO_EXPORT_PATH, "wt");
     if (!f)
@@ -237,10 +239,11 @@ static int VbGetGpioStatus(unsigned gpio_number) {
     fclose(f);
 
     /* Try re-reading the GPIO value */
-    value = ReadFileInt(gpio_name);
+    if (ReadFileInt(gpio_name, &value) < 0)
+      return -1;
   }
 
-  return value;
+  return (int)value;
 }
 
 static int VbGetVarGpio(const char* name) {