Richard Spiegel has uploaded this change for review.
lib/gpio.c: Fix _gpio_base3_value invalid shift
In function _gpio_base3_value(), if gpio_num is 32 and gpio[31] is floating,
the end result is 1 << 32, which does not fit into a int. To avoid a possible
error, in this condition set value to 0xffffffff.
Add a comment explaining why and the work around.
BUG=b:113788440
TEST=Add a fake code to southbridge_final calling the function and printing
the result. Build and boot grunt, check result.
Change-Id: I0b79725bcbaf120587c7440e176643aaa7a1d5bb
Signed-off-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
---
M src/lib/gpio.c
1 file changed, 13 insertions(+), 2 deletions(-)
git pull ssh://review.coreboot.org:29418/coreboot refs/changes/45/28445/1
diff --git a/src/lib/gpio.c b/src/lib/gpio.c
index da74849..4549166 100644
--- a/src/lib/gpio.c
+++ b/src/lib/gpio.c
@@ -75,7 +75,7 @@
* internally pulled to.
*/
- static const char tristate_char[] = {[0] = '0', [1] = '1', [Z] = 'Z'};
+ static const char tristate_char[] = {[0] = '0', [1] = '1', [2] = 'Z'};
uint32_t result = 0;
int has_z = 0;
int binary_below = 0;
@@ -138,6 +138,14 @@
* '2' at 3^1: Add 2^(1+1) = 4 to account for binaries 1000-1011
* Stop adding for lower digits (3^0), all already accounted
* now. We know that there can be no binary numbers 1020-102X.
+ *
+ * If gpio_num is 32 and gpio[31] is floating, the end result is
+ * 1 << 32, which does not fit into a int. To avoid a possible
+ * error, in this condition the value will be set to 0xffffffff.
+ * There's a second condition which would set this value, to
+ * have all inputs as 1. To differentiate between these results,
+ * the caller needs to test if gpio[31] is floating. If gpio_num
+ * is less than 32, no care is needed.
*/
if (binary_first && !has_z) {
switch (temp) {
@@ -147,7 +155,10 @@
binary_below += 1 << index;
break;
case 2: /* Account for binaries 0 to 2^(index+1) - 1. */
- binary_below += 1 << (index + 1);
+ if (index >= 31)
+ binary_below = 0xffffffff;
+ else
+ binary_below += 1 << (index + 1);
has_z = 1;
}
}
To view, visit change 28445. To unsubscribe, or for help writing mail filters, visit settings.