Merge branch 'gigaset_modem_response'

Tilman Schmidt says:

====================
isdn/gigaset: restructure modem response parser

This series of patches restructures the Gigaset ISDN driver's
modem response parser to improve code readability and conform
better to the device's specification and actual behaviour.
Could you please merge these through net-next?
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 195 insertions, 170 deletions

diff --git a/drivers/isdn/gigaset/ev-layer.c b/drivers/isdn/gigaset/ev-layer.c
index c8ced12fa452..1cfcea62aed9 100644
--- a/drivers/isdn/gigaset/ev-layer.c
+++ b/drivers/isdn/gigaset/ev-layer.c
@@ -389,22 +389,49 @@ zsau_resp[] =
 	{NULL,				ZSAU_UNKNOWN}
 };
 
-/* retrieve CID from parsed response
- * returns 0 if no CID, -1 if invalid CID, or CID value 1..65535
+/* check for and remove fixed string prefix
+ * If s starts with prefix terminated by a non-alphanumeric character,
+ * return pointer to the first character after that, otherwise return NULL.
  */
-static int cid_of_response(char *s)
+static char *skip_prefix(char *s, const char *prefix)
 {
-	int cid;
-	int rc;
-
-	if (s[-1] != ';')
-		return 0;	/* no CID separator */
-	rc = kstrtoint(s, 10, &cid);
-	if (rc)
-		return 0;	/* CID not numeric */
-	if (cid < 1 || cid > 65535)
-		return -1;	/* CID out of range */
-	return cid;
+	while (*prefix)
+		if (*s++ != *prefix++)
+			return NULL;
+	if (isalnum(*s))
+		return NULL;
+	return s;
+}
+
+/* queue event with CID */
+static void add_cid_event(struct cardstate *cs, int cid, int type,
+			  void *ptr, int parameter)
+{
+	unsigned long flags;
+	unsigned next, tail;
+	struct event_t *event;
+
+	gig_dbg(DEBUG_EVENT, "queueing event %d for cid %d", type, cid);
+
+	spin_lock_irqsave(&cs->ev_lock, flags);
+
+	tail = cs->ev_tail;
+	next = (tail + 1) % MAX_EVENTS;
+	if (unlikely(next == cs->ev_head)) {
+		dev_err(cs->dev, "event queue full\n");
+		kfree(ptr);
+	} else {
+		event = cs->events + tail;
+		event->type = type;
+		event->cid = cid;
+		event->ptr = ptr;
+		event->arg = NULL;
+		event->parameter = parameter;
+		event->at_state = NULL;
+		cs->ev_tail = next;
+	}
+
+	spin_unlock_irqrestore(&cs->ev_lock, flags);
 }
 
 /**
@@ -417,190 +444,188 @@ static int cid_of_response(char *s)
  */
 void gigaset_handle_modem_response(struct cardstate *cs)
 {
-	unsigned char *argv[MAX_REC_PARAMS + 1];
-	int params;
-	int i, j;
+	char *eoc, *psep, *ptr;
 	const struct resp_type_t *rt;
 	const struct zsau_resp_t *zr;
-	int curarg;
-	unsigned long flags;
-	unsigned next, tail, head;
-	struct event_t *event;
-	int resp_code;
-	int param_type;
-	int abort;
-	size_t len;
-	int cid;
-	int rawstring;
-
-	len = cs->cbytes;
-	if (!len) {
+	int cid, parameter;
+	u8 type, value;
+
+	if (!cs->cbytes) {
 		/* ignore additional LFs/CRs (M10x config mode or cx100) */
 		gig_dbg(DEBUG_MCMD, "skipped EOL [%02X]", cs->respdata[0]);
 		return;
 	}
-	cs->respdata[len] = 0;
-	argv[0] = cs->respdata;
-	params = 1;
+	cs->respdata[cs->cbytes] = 0;
+
 	if (cs->at_state.getstring) {
-		/* getstring only allowed without cid at the moment */
+		/* state machine wants next line verbatim */
 		cs->at_state.getstring = 0;
-		rawstring = 1;
-		cid = 0;
-	} else {
-		/* parse line */
-		for (i = 0; i < len; i++)
-			switch (cs->respdata[i]) {
-			case ';':
-			case ',':
-			case '=':
-				if (params > MAX_REC_PARAMS) {
-					dev_warn(cs->dev,
-						 "too many parameters in response\n");
-					/* need last parameter (might be CID) */
-					params--;
-				}
-				argv[params++] = cs->respdata + i + 1;
-			}
-
-		rawstring = 0;
-		cid = params > 1 ? cid_of_response(argv[params - 1]) : 0;
-		if (cid < 0) {
-			gigaset_add_event(cs, &cs->at_state, RSP_INVAL,
-					  NULL, 0, NULL);
-			return;
-		}
+		ptr = kstrdup(cs->respdata, GFP_ATOMIC);
+		gig_dbg(DEBUG_EVENT, "string==%s", ptr ? ptr : "NULL");
+		add_cid_event(cs, 0, RSP_STRING, ptr, 0);
+		return;
+	}
 
-		for (j = 1; j < params; ++j)
-			argv[j][-1] = 0;
+	/* look up response type */
+	for (rt = resp_type; rt->response; ++rt) {
+		eoc = skip_prefix(cs->respdata, rt->response);
+		if (eoc)
+			break;
+	}
+	if (!rt->response) {
+		add_cid_event(cs, 0, RSP_NONE, NULL, 0);
+		gig_dbg(DEBUG_EVENT, "unknown modem response: '%s'\n",
+			cs->respdata);
+		return;
+	}
 
-		gig_dbg(DEBUG_EVENT, "CMD received: %s", argv[0]);
-		if (cid) {
-			--params;
-			gig_dbg(DEBUG_EVENT, "CID: %s", argv[params]);
-		}
-		gig_dbg(DEBUG_EVENT, "available params: %d", params - 1);
-		for (j = 1; j < params; j++)
-			gig_dbg(DEBUG_EVENT, "param %d: %s", j, argv[j]);
+	/* check for CID */
+	psep = strrchr(cs->respdata, ';');
+	if (psep &&
+	    !kstrtoint(psep + 1, 10, &cid) &&
+	    cid >= 1 && cid <= 65535) {
+		/* valid CID: chop it off */
+		*psep = 0;
+	} else {
+		/* no valid CID: leave unchanged */
+		cid = 0;
 	}
 
-	spin_lock_irqsave(&cs->ev_lock, flags);
-	head = cs->ev_head;
-	tail = cs->ev_tail;
+	gig_dbg(DEBUG_EVENT, "CMD received: %s", cs->respdata);
+	if (cid)
+		gig_dbg(DEBUG_EVENT, "CID: %d", cid);
 
-	abort = 1;
-	curarg = 0;
-	while (curarg < params) {
-		next = (tail + 1) % MAX_EVENTS;
-		if (unlikely(next == head)) {
-			dev_err(cs->dev, "event queue full\n");
-			break;
-		}
+	switch (rt->type) {
+	case RT_NOTHING:
+		/* check parameter separator */
+		if (*eoc)
+			goto bad_param;	/* extra parameter */
 
-		event = cs->events + tail;
-		event->at_state = NULL;
-		event->cid = cid;
-		event->ptr = NULL;
-		event->arg = NULL;
-		tail = next;
+		add_cid_event(cs, cid, rt->resp_code, NULL, 0);
+		break;
 
-		if (rawstring) {
-			resp_code = RSP_STRING;
-			param_type = RT_STRING;
-		} else {
-			for (rt = resp_type; rt->response; ++rt)
-				if (!strcmp(argv[curarg], rt->response))
+	case RT_RING:
+		/* check parameter separator */
+		if (!*eoc)
+			eoc = NULL;	/* no parameter */
+		else if (*eoc++ != ',')
+			goto bad_param;
+
+		add_cid_event(cs, 0, rt->resp_code, NULL, cid);
+
+		/* process parameters as individual responses */
+		while (eoc) {
+			/* look up parameter type */
+			psep = NULL;
+			for (rt = resp_type; rt->response; ++rt) {
+				psep = skip_prefix(eoc, rt->response);
+				if (psep)
 					break;
+			}
 
-			if (!rt->response) {
-				event->type = RSP_NONE;
-				gig_dbg(DEBUG_EVENT,
-					"unknown modem response: '%s'\n",
-					argv[curarg]);
-				break;
+			/* all legal parameters are of type RT_STRING */
+			if (!psep || rt->type != RT_STRING) {
+				dev_warn(cs->dev,
+					 "illegal RING parameter: '%s'\n",
+					 eoc);
+				return;
 			}
 
-			resp_code = rt->resp_code;
-			param_type = rt->type;
-			++curarg;
-		}
+			/* skip parameter value separator */
+			if (*psep++ != '=')
+				goto bad_param;
 
-		event->type = resp_code;
+			/* look up end of parameter */
+			eoc = strchr(psep, ',');
+			if (eoc)
+				*eoc++ = 0;
 
-		switch (param_type) {
-		case RT_NOTHING:
-			break;
-		case RT_RING:
-			if (!cid) {
-				dev_err(cs->dev,
-					"received RING without CID!\n");
-				event->type = RSP_INVAL;
-				abort = 1;
-			} else {
-				event->cid = 0;
-				event->parameter = cid;
-				abort = 0;
-			}
+			/* retrieve parameter value */
+			ptr = kstrdup(psep, GFP_ATOMIC);
+
+			/* queue event */
+			add_cid_event(cs, cid, rt->resp_code, ptr, 0);
+		}
+		break;
+
+	case RT_ZSAU:
+		/* check parameter separator */
+		if (!*eoc) {
+			/* no parameter */
+			add_cid_event(cs, cid, rt->resp_code, NULL, ZSAU_NONE);
 			break;
-		case RT_ZSAU:
-			if (curarg >= params) {
-				event->parameter = ZSAU_NONE;
+		}
+		if (*eoc++ != '=')
+			goto bad_param;
+
+		/* look up parameter value */
+		for (zr = zsau_resp; zr->str; ++zr)
+			if (!strcmp(eoc, zr->str))
 				break;
-			}
-			for (zr = zsau_resp; zr->str; ++zr)
-				if (!strcmp(argv[curarg], zr->str))
-					break;
-			event->parameter = zr->code;
-			if (!zr->str)
-				dev_warn(cs->dev,
-					 "%s: unknown parameter %s after ZSAU\n",
-					 __func__, argv[curarg]);
-			++curarg;
-			break;
-		case RT_STRING:
-			if (curarg < params) {
-				event->ptr = kstrdup(argv[curarg], GFP_ATOMIC);
-				if (!event->ptr)
-					dev_err(cs->dev, "out of memory\n");
-				++curarg;
-			}
-			gig_dbg(DEBUG_EVENT, "string==%s",
-				event->ptr ? (char *) event->ptr : "NULL");
-			break;
-		case RT_ZCAU:
-			event->parameter = -1;
-			if (curarg + 1 < params) {
-				u8 type, value;
-
-				i = kstrtou8(argv[curarg++], 16, &type);
-				j = kstrtou8(argv[curarg++], 16, &value);
-				if (i == 0 && j == 0)
-					event->parameter = (type << 8) | value;
-			} else
-				curarg = params - 1;
-			break;
-		case RT_NUMBER:
-			if (curarg >= params ||
-			    kstrtoint(argv[curarg++], 10, &event->parameter))
-				event->parameter = -1;
-			gig_dbg(DEBUG_EVENT, "parameter==%d", event->parameter);
-			break;
+		if (!zr->str)
+			goto bad_param;
+
+		add_cid_event(cs, cid, rt->resp_code, NULL, zr->code);
+		break;
+
+	case RT_STRING:
+		/* check parameter separator */
+		if (*eoc++ != '=')
+			goto bad_param;
+
+		/* retrieve parameter value */
+		ptr = kstrdup(eoc, GFP_ATOMIC);
+
+		/* queue event */
+		add_cid_event(cs, cid, rt->resp_code, ptr, 0);
+		break;
+
+	case RT_ZCAU:
+		/* check parameter separators */
+		if (*eoc++ != '=')
+			goto bad_param;
+		psep = strchr(eoc, ',');
+		if (!psep)
+			goto bad_param;
+		*psep++ = 0;
+
+		/* decode parameter values */
+		if (kstrtou8(eoc, 16, &type) || kstrtou8(psep, 16, &value)) {
+			*--psep = ',';
+			goto bad_param;
 		}
+		parameter = (type << 8) | value;
 
-		if (resp_code == RSP_ZDLE)
-			cs->dle = event->parameter;
+		add_cid_event(cs, cid, rt->resp_code, NULL, parameter);
+		break;
 
-		if (abort)
-			break;
-	}
+	case RT_NUMBER:
+		/* check parameter separator */
+		if (*eoc++ != '=')
+			goto bad_param;
 
-	cs->ev_tail = tail;
-	spin_unlock_irqrestore(&cs->ev_lock, flags);
+		/* decode parameter value */
+		if (kstrtoint(eoc, 10, &parameter))
+			goto bad_param;
+
+		/* special case ZDLE: set flag before queueing event */
+		if (rt->resp_code == RSP_ZDLE)
+			cs->dle = parameter;
 
-	if (curarg != params)
-		gig_dbg(DEBUG_EVENT,
-			"invalid number of processed parameters: %d/%d",
-			curarg, params);
+		add_cid_event(cs, cid, rt->resp_code, NULL, parameter);
+		break;
+
+bad_param:
+		/* parameter unexpected, incomplete or malformed */
+		dev_warn(cs->dev, "bad parameter in response '%s'\n",
+			 cs->respdata);
+		add_cid_event(cs, cid, rt->resp_code, NULL, -1);
+		break;
+
+	default:
+		dev_err(cs->dev, "%s: internal error on '%s'\n",
+			__func__, cs->respdata);
+	}
 }
 EXPORT_SYMBOL_GPL(gigaset_handle_modem_response);