libpayload/keyboard: Revise keyboard_cmd() error handling
Even if we are careful, it's still possible that we read spurious
data from the keyboard, e.g. keystrokes. Namely, when we send the
reset/disable command, there is a race before the command is pro-
cessed.
So we should always process data from the keyboard in a loop. We
break it, when an ACK (0xfa) or a NAK (0xfe) is received, and warn
on unexpected data unless it might be due to the mentioned race.
This also gives us the opportunity to use command-specific timeouts
which we take from Linux: 1s for the keyboard self-test (as there
are keyboards that perform the test before acking the command) and
200ms for all other commands.
Change-Id: I60a2643a8ff4b9231c63bf970c8749c97c7d8926
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47083
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/payloads/libpayload/drivers/i8042/keyboard.c b/payloads/libpayload/drivers/i8042/keyboard.c
index 22747ff..42d4fdc 100644
--- a/payloads/libpayload/drivers/i8042/keyboard.c
+++ b/payloads/libpayload/drivers/i8042/keyboard.c
@@ -28,6 +28,7 @@
*/
#include <stdbool.h>
+#include <stdint.h>
#include <keycodes.h>
#include <libpayload-config.h>
@@ -173,9 +174,33 @@
static bool keyboard_cmd(unsigned char cmd)
{
+ const uint64_t timeout_us = cmd == I8042_KBCMD_RESET ? 1*1000*1000 : 200*1000;
+ const uint64_t start_time = timer_us(0);
+
i8042_write_data(cmd);
- return i8042_wait_read_ps2() == 0xfa;
+ do {
+ if (!i8042_data_ready_ps2()) {
+ udelay(50);
+ continue;
+ }
+
+ const uint8_t data = i8042_read_data_ps2();
+ switch (data) {
+ case 0xfa:
+ return true;
+ case 0xfe:
+ return false;
+ default:
+ /* Warn only if we already disabled keyboard input. */
+ if (cmd != I8042_KBCMD_DEFAULT_DIS)
+ printf("WARNING: Keyboard sent spurious 0x%02x.\n", data);
+ break;
+ }
+ } while (timer_us(start_time) < timeout_us);
+
+ printf("ERROR: Keyboard command timed out.\n");
+ return false;
}
bool keyboard_havechar(void)