[PATCH] ratp: only allow bidirectional consoles

[Aleksander Morgado]

Ignore requests to switch to RATP mode in input-only or output-only
consoles.

This actually also avoids segfaulting later on:

    #0  0x0000000000000000 in ?? ()
    #1  0x000000000040b2a4 in console_send (r=<optimized out>, pkt=0x7fffffffd8ec, len=4) at common/ratp.c:102
    #2  0x000000000042ab99 in ratp_behaviour_a (pkt=0x7ffff7298780, ri=0x7ffff72766d0) at lib/ratp.c:530
    #3  ratp_state_machine (pkt=0x7ffff7298780, ri=0x7ffff72766d0) at lib/ratp.c:1384
    #4  ratp_poll (ratp=0x7ffff7277ed8) at lib/ratp.c:1561
    #5  0x000000000042b2ab in ratp_establish (ratp=ratp at entry=0x7ffff7277ed8, active=active at entry=false, timeout_ms=timeout_ms at entry=100) at lib/ratp.c:1645
    #6  0x000000000040b888 in barebox_ratp (cdev=cdev at entry=0x7ffff7212bd0) at common/ratp.c:470
    #7  0x00000000004046c3 in getc_raw () at common/console.c:416
    ...

Signed-off-by: Aleksander Morgado <aleksander at aleksander.es>
---
 common/ratp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/common/ratp.c b/common/ratp.c
index e879e2b3c..7be86d49a 100644
--- a/common/ratp.c
+++ b/common/ratp.c
@@ -443,6 +443,9 @@ int barebox_ratp(struct console_device *cdev)
 	struct ratp_ctx *ctx;
 	struct ratp *ratp;

+	if (!cdev->getc || !cdev->putc)
+		return -EINVAL;
+
 	if (ratp_command_ctx) {
 		ctx = ratp_command_ctx;
 	} else {
--
2.12.2