[PATCH v2 1/6] tty: n_gsm: add enumeration for gsm encodings

From: D. Starke
Date: Tue Aug 23 2022 - 02:25:40 EST


From: Daniel Starke <daniel.starke@xxxxxxxxxxx>

Add an enumeration for the gsm mux encoding types to improve code
readability and to avoid invalid values. Only two values are defined by the
standard:
- basic option mode
- advanced option mode (uses ISO HDLC standard transparency mechanism)

Also remove redundant configuration in gsmld_open(). The same value is
already set in gsm_alloc_mux() which is also called in gsmld_open().

Signed-off-by: Daniel Starke <daniel.starke@xxxxxxxxxxx>
---
drivers/tty/n_gsm.c | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)

No changes since v1.

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index caa5c14ed57f..5bf09d129357 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -184,6 +184,11 @@ struct gsm_control {
int error; /* Error if any */
};

+enum gsm_encoding {
+ GSM_BASIC_OPT,
+ GSM_ADV_OPT,
+};
+
enum gsm_mux_state {
GSM_SEARCH,
GSM_START,
@@ -230,7 +235,7 @@ struct gsm_mux {
unsigned int address;
unsigned int count;
bool escape;
- int encoding;
+ enum gsm_encoding encoding;
u8 control;
u8 fcs;
u8 *txframe; /* TX framing buffer */
@@ -694,7 +699,7 @@ static int gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
*dp++ = (addr << 2) | (ocr << 1) | EA;
*dp++ = control;

- if (gsm->encoding == 0)
+ if (gsm->encoding == GSM_BASIC_OPT)
*dp++ = EA; /* Length of data = 0 */

*dp = 0xFF - gsm_fcs_add_block(INIT_FCS, msg->data, dp - msg->data);
@@ -813,7 +818,7 @@ static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg)
int len, ret;


- if (gsm->encoding == 0) {
+ if (gsm->encoding == GSM_BASIC_OPT) {
gsm->txframe[0] = GSM0_SOF;
memcpy(gsm->txframe + 1, msg->data, msg->len);
gsm->txframe[msg->len + 1] = GSM0_SOF;
@@ -965,7 +970,7 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
u8 *fcs = dp + msg->len;

/* Fill in the header */
- if (gsm->encoding == 0) {
+ if (gsm->encoding == GSM_BASIC_OPT) {
if (msg->len < 128)
*--dp = (msg->len << 1) | EA;
else {
@@ -2508,7 +2513,7 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
spin_lock_init(&gsm->control_lock);
spin_lock_init(&gsm->tx_lock);

- if (gsm->encoding == 0)
+ if (gsm->encoding == GSM_BASIC_OPT)
gsm->receive = gsm0_receive;
else
gsm->receive = gsm1_receive;
@@ -2618,7 +2623,7 @@ static struct gsm_mux *gsm_alloc_mux(void)
gsm->n2 = N2;
gsm->ftype = UIH;
gsm->adaption = 1;
- gsm->encoding = 1;
+ gsm->encoding = GSM_ADV_OPT;
gsm->mru = 64; /* Default to encoding 1 so these should be 64 */
gsm->mtu = 64;
gsm->dead = true; /* Avoid early tty opens */
@@ -2651,7 +2656,7 @@ static void gsm_copy_config_values(struct gsm_mux *gsm,
{
memset(c, 0, sizeof(*c));
c->adaption = gsm->adaption;
- c->encapsulation = gsm->encoding;
+ c->encapsulation = (int)gsm->encoding;
c->initiator = gsm->initiator;
c->t1 = gsm->t1;
c->t2 = gsm->t2;
@@ -2719,7 +2724,7 @@ static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
gsm->initiator = c->initiator;
gsm->mru = c->mru;
gsm->mtu = c->mtu;
- gsm->encoding = c->encapsulation;
+ gsm->encoding = c->encapsulation ? GSM_ADV_OPT : GSM_BASIC_OPT;
gsm->adaption = c->adaption;
gsm->n2 = c->n2;

@@ -2942,8 +2947,6 @@ static int gsmld_open(struct tty_struct *tty)
tty->receive_room = 65536;

/* Attach the initial passive connection */
- gsm->encoding = 1;
-
gsmld_attach_gsm(tty, gsm);

timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);
@@ -3345,7 +3348,7 @@ static int gsm_modem_upd_via_msc(struct gsm_dlci *dlci, u8 brk)
struct gsm_control *ctrl;
int len = 2;

- if (dlci->gsm->encoding != 0)
+ if (dlci->gsm->encoding != GSM_BASIC_OPT)
return 0;

modembits[0] = (dlci->addr << 2) | 2 | EA; /* DLCI, Valid, EA */
@@ -3374,7 +3377,7 @@ static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
/* Send convergence layer type 2 empty data frame. */
gsm_modem_upd_via_data(dlci, brk);
return 0;
- } else if (dlci->gsm->encoding == 0) {
+ } else if (dlci->gsm->encoding == GSM_BASIC_OPT) {
/* Send as MSC control message. */
return gsm_modem_upd_via_msc(dlci, brk);
}
@@ -3398,8 +3401,8 @@ static int gsm_carrier_raised(struct tty_port *port)
* Basic mode with control channel in ADM mode may not respond
* to CMD_MSC at all and modem_rx is empty.
*/
- if (gsm->encoding == 0 && gsm->dlci[0]->mode == DLCI_MODE_ADM &&
- !dlci->modem_rx)
+ if (gsm->encoding == GSM_BASIC_OPT &&
+ gsm->dlci[0]->mode == DLCI_MODE_ADM && !dlci->modem_rx)
return 1;

return dlci->modem_rx & TIOCM_CD;
--
2.34.1