lib/gpio.c: Fix _gpio_base3_value invalid shift

Coverity CID 1395334: (BAD_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, make it an error to have
num_gpio > 31. Function _gpio_base2_value also have the same issue, but the
limit would be 32. As in practice it'll never be used with more than 20 GPIO,
create a helper function to limit it to 31 and call it everywhere needed.

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>
Reviewed-on: https://review.coreboot.org/28445
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

0 files changed, 0 insertions, 0 deletions