1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2020-21 Intel Corporation.
4  */
5 
6 #include <linux/etherdevice.h>
7 #include <linux/if_arp.h>
8 #include <linux/if_link.h>
9 #include <linux/rtnetlink.h>
10 #include <linux/wwan.h>
11 
12 #include "iosm_ipc_chnl_cfg.h"
13 #include "iosm_ipc_imem_ops.h"
14 #include "iosm_ipc_wwan.h"
15 
16 #define IOSM_IP_TYPE_MASK 0xF0
17 #define IOSM_IP_TYPE_IPV4 0x40
18 #define IOSM_IP_TYPE_IPV6 0x60
19 
20 #define IOSM_IF_ID_PAYLOAD 2
21 
22 /**
23  * struct iosm_netdev_priv - netdev WWAN driver specific private data
24  * @ipc_wwan:	Pointer to iosm_wwan struct
25  * @netdev:	Pointer to network interface device structure
26  * @if_id:	Interface id for device.
27  * @ch_id:	IPC channel number for which interface device is created.
28  */
29 struct iosm_netdev_priv {
30 	struct iosm_wwan *ipc_wwan;
31 	struct net_device *netdev;
32 	int if_id;
33 	int ch_id;
34 };
35 
36 /**
37  * struct iosm_wwan - This structure contains information about WWAN root device
38  *		      and interface to the IPC layer.
39  * @ipc_imem:		Pointer to imem data-struct
40  * @sub_netlist:	List of active netdevs
41  * @dev:		Pointer device structure
42  * @if_mutex:		Mutex used for add and remove interface id
43  */
44 struct iosm_wwan {
45 	struct iosm_imem *ipc_imem;
46 	struct iosm_netdev_priv __rcu *sub_netlist[IP_MUX_SESSION_END + 1];
47 	struct device *dev;
48 	struct mutex if_mutex; /* Mutex used for add and remove interface id */
49 };
50 
51 /* Bring-up the wwan net link */
52 static int ipc_wwan_link_open(struct net_device *netdev)
53 {
54 	struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(netdev);
55 	struct iosm_wwan *ipc_wwan = priv->ipc_wwan;
56 	int if_id = priv->if_id;
57 	int ret;
58 
59 	if (if_id < IP_MUX_SESSION_START ||
60 	    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
61 		return -EINVAL;
62 
63 	mutex_lock(&ipc_wwan->if_mutex);
64 
65 	/* get channel id */
66 	priv->ch_id = ipc_imem_sys_wwan_open(ipc_wwan->ipc_imem, if_id);
67 
68 	if (priv->ch_id < 0) {
69 		dev_err(ipc_wwan->dev,
70 			"cannot connect wwan0 & id %d to the IPC mem layer",
71 			if_id);
72 		ret = -ENODEV;
73 		goto out;
74 	}
75 
76 	/* enable tx path, DL data may follow */
77 	netif_start_queue(netdev);
78 
79 	dev_dbg(ipc_wwan->dev, "Channel id %d allocated to if_id %d",
80 		priv->ch_id, priv->if_id);
81 
82 	ret = 0;
83 out:
84 	mutex_unlock(&ipc_wwan->if_mutex);
85 	return ret;
86 }
87 
88 /* Bring-down the wwan net link */
89 static int ipc_wwan_link_stop(struct net_device *netdev)
90 {
91 	struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(netdev);
92 
93 	netif_stop_queue(netdev);
94 
95 	mutex_lock(&priv->ipc_wwan->if_mutex);
96 	ipc_imem_sys_wwan_close(priv->ipc_wwan->ipc_imem, priv->if_id,
97 				priv->ch_id);
98 	priv->ch_id = -1;
99 	mutex_unlock(&priv->ipc_wwan->if_mutex);
100 
101 	return 0;
102 }
103 
104 /* Transmit a packet */
105 static int ipc_wwan_link_transmit(struct sk_buff *skb,
106 				  struct net_device *netdev)
107 {
108 	struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(netdev);
109 	struct iosm_wwan *ipc_wwan = priv->ipc_wwan;
110 	unsigned int len = skb->len;
111 	int if_id = priv->if_id;
112 	int ret;
113 
114 	/* Interface IDs from 1 to 8 are for IP data
115 	 * & from 257 to 261 are for non-IP data
116 	 */
117 	if (if_id < IP_MUX_SESSION_START ||
118 	    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
119 		return -EINVAL;
120 
121 	/* Send the SKB to device for transmission */
122 	ret = ipc_imem_sys_wwan_transmit(ipc_wwan->ipc_imem,
123 					 if_id, priv->ch_id, skb);
124 
125 	/* Return code of zero is success */
126 	if (ret == 0) {
127 		netdev->stats.tx_packets++;
128 		netdev->stats.tx_bytes += len;
129 		ret = NETDEV_TX_OK;
130 	} else if (ret == -EBUSY) {
131 		ret = NETDEV_TX_BUSY;
132 		dev_err(ipc_wwan->dev, "unable to push packets");
133 	} else {
134 		goto exit;
135 	}
136 
137 	return ret;
138 
139 exit:
140 	/* Log any skb drop */
141 	if (if_id)
142 		dev_dbg(ipc_wwan->dev, "skb dropped. IF_ID: %d, ret: %d", if_id,
143 			ret);
144 
145 	dev_kfree_skb_any(skb);
146 	netdev->stats.tx_dropped++;
147 	return NETDEV_TX_OK;
148 }
149 
150 /* Ops structure for wwan net link */
151 static const struct net_device_ops ipc_inm_ops = {
152 	.ndo_open = ipc_wwan_link_open,
153 	.ndo_stop = ipc_wwan_link_stop,
154 	.ndo_start_xmit = ipc_wwan_link_transmit,
155 };
156 
157 /* Setup function for creating new net link */
158 static void ipc_wwan_setup(struct net_device *iosm_dev)
159 {
160 	iosm_dev->header_ops = NULL;
161 	iosm_dev->hard_header_len = 0;
162 	iosm_dev->priv_flags |= IFF_NO_QUEUE;
163 
164 	iosm_dev->type = ARPHRD_NONE;
165 	iosm_dev->mtu = ETH_DATA_LEN;
166 	iosm_dev->min_mtu = ETH_MIN_MTU;
167 	iosm_dev->max_mtu = ETH_MAX_MTU;
168 
169 	iosm_dev->flags = IFF_POINTOPOINT | IFF_NOARP;
170 
171 	iosm_dev->netdev_ops = &ipc_inm_ops;
172 }
173 
174 /* Create new wwan net link */
175 static int ipc_wwan_newlink(void *ctxt, struct net_device *dev,
176 			    u32 if_id, struct netlink_ext_ack *extack)
177 {
178 	struct iosm_wwan *ipc_wwan = ctxt;
179 	struct iosm_netdev_priv *priv;
180 	int err;
181 
182 	if (if_id < IP_MUX_SESSION_START ||
183 	    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
184 		return -EINVAL;
185 
186 	priv = wwan_netdev_drvpriv(dev);
187 	priv->if_id = if_id;
188 	priv->netdev = dev;
189 	priv->ipc_wwan = ipc_wwan;
190 
191 	mutex_lock(&ipc_wwan->if_mutex);
192 	if (rcu_access_pointer(ipc_wwan->sub_netlist[if_id])) {
193 		err = -EBUSY;
194 		goto out_unlock;
195 	}
196 
197 	err = register_netdevice(dev);
198 	if (err)
199 		goto out_unlock;
200 
201 	rcu_assign_pointer(ipc_wwan->sub_netlist[if_id], priv);
202 	mutex_unlock(&ipc_wwan->if_mutex);
203 
204 	netif_device_attach(dev);
205 
206 	return 0;
207 
208 out_unlock:
209 	mutex_unlock(&ipc_wwan->if_mutex);
210 	return err;
211 }
212 
213 static void ipc_wwan_dellink(void *ctxt, struct net_device *dev,
214 			     struct list_head *head)
215 {
216 	struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(dev);
217 	struct iosm_wwan *ipc_wwan = ctxt;
218 	int if_id = priv->if_id;
219 
220 	if (WARN_ON(if_id < IP_MUX_SESSION_START ||
221 		    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist)))
222 		return;
223 
224 	mutex_lock(&ipc_wwan->if_mutex);
225 
226 	if (WARN_ON(rcu_access_pointer(ipc_wwan->sub_netlist[if_id]) != priv))
227 		goto unlock;
228 
229 	RCU_INIT_POINTER(ipc_wwan->sub_netlist[if_id], NULL);
230 	/* unregistering includes synchronize_net() */
231 	unregister_netdevice_queue(dev, head);
232 
233 unlock:
234 	mutex_unlock(&ipc_wwan->if_mutex);
235 }
236 
237 static const struct wwan_ops iosm_wwan_ops = {
238 	.priv_size = sizeof(struct iosm_netdev_priv),
239 	.setup = ipc_wwan_setup,
240 	.newlink = ipc_wwan_newlink,
241 	.dellink = ipc_wwan_dellink,
242 };
243 
244 int ipc_wwan_receive(struct iosm_wwan *ipc_wwan, struct sk_buff *skb_arg,
245 		     bool dss, int if_id)
246 {
247 	struct sk_buff *skb = skb_arg;
248 	struct net_device_stats *stats;
249 	struct iosm_netdev_priv *priv;
250 	int ret;
251 
252 	if ((skb->data[0] & IOSM_IP_TYPE_MASK) == IOSM_IP_TYPE_IPV4)
253 		skb->protocol = htons(ETH_P_IP);
254 	else if ((skb->data[0] & IOSM_IP_TYPE_MASK) ==
255 		 IOSM_IP_TYPE_IPV6)
256 		skb->protocol = htons(ETH_P_IPV6);
257 
258 	skb->pkt_type = PACKET_HOST;
259 
260 	if (if_id < IP_MUX_SESSION_START ||
261 	    if_id > IP_MUX_SESSION_END) {
262 		ret = -EINVAL;
263 		goto free;
264 	}
265 
266 	rcu_read_lock();
267 	priv = rcu_dereference(ipc_wwan->sub_netlist[if_id]);
268 	if (!priv) {
269 		ret = -EINVAL;
270 		goto unlock;
271 	}
272 	skb->dev = priv->netdev;
273 	stats = &priv->netdev->stats;
274 	stats->rx_packets++;
275 	stats->rx_bytes += skb->len;
276 
277 	ret = netif_rx(skb);
278 	skb = NULL;
279 unlock:
280 	rcu_read_unlock();
281 free:
282 	dev_kfree_skb(skb);
283 	return ret;
284 }
285 
286 void ipc_wwan_tx_flowctrl(struct iosm_wwan *ipc_wwan, int if_id, bool on)
287 {
288 	struct net_device *netdev;
289 	struct iosm_netdev_priv *priv;
290 	bool is_tx_blk;
291 
292 	rcu_read_lock();
293 	priv = rcu_dereference(ipc_wwan->sub_netlist[if_id]);
294 	if (!priv) {
295 		rcu_read_unlock();
296 		return;
297 	}
298 
299 	netdev = priv->netdev;
300 
301 	is_tx_blk = netif_queue_stopped(netdev);
302 
303 	if (on)
304 		dev_dbg(ipc_wwan->dev, "session id[%d]: flowctrl enable",
305 			if_id);
306 
307 	if (on && !is_tx_blk)
308 		netif_stop_queue(netdev);
309 	else if (!on && is_tx_blk)
310 		netif_wake_queue(netdev);
311 	rcu_read_unlock();
312 }
313 
314 struct iosm_wwan *ipc_wwan_init(struct iosm_imem *ipc_imem, struct device *dev)
315 {
316 	struct iosm_wwan *ipc_wwan;
317 
318 	ipc_wwan = kzalloc(sizeof(*ipc_wwan), GFP_KERNEL);
319 	if (!ipc_wwan)
320 		return NULL;
321 
322 	ipc_wwan->dev = dev;
323 	ipc_wwan->ipc_imem = ipc_imem;
324 
325 	/* WWAN core will create a netdev for the default IP MUX channel */
326 	if (wwan_register_ops(ipc_wwan->dev, &iosm_wwan_ops, ipc_wwan,
327 			      IP_MUX_SESSION_DEFAULT)) {
328 		kfree(ipc_wwan);
329 		return NULL;
330 	}
331 
332 	mutex_init(&ipc_wwan->if_mutex);
333 
334 	return ipc_wwan;
335 }
336 
337 void ipc_wwan_deinit(struct iosm_wwan *ipc_wwan)
338 {
339 	/* This call will remove all child netdev(s) */
340 	wwan_unregister_ops(ipc_wwan->dev);
341 
342 	mutex_destroy(&ipc_wwan->if_mutex);
343 
344 	kfree(ipc_wwan);
345 }
346