1 // SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
2 /*
3 * Copyright (c) 2011, 2012, Qualcomm Atheros Communications Inc.
4 * Copyright (c) 2017, I2SE GmbH
5 */
6
7 /* This module implements the Qualcomm Atheros UART protocol for
8 * kernel-based UART device; it is essentially an Ethernet-to-UART
9 * serial converter;
10 */
11
12 #include <linux/device.h>
13 #include <linux/errno.h>
14 #include <linux/etherdevice.h>
15 #include <linux/if_arp.h>
16 #include <linux/if_ether.h>
17 #include <linux/jiffies.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/netdevice.h>
21 #include <linux/of.h>
22 #include <linux/of_net.h>
23 #include <linux/sched.h>
24 #include <linux/serdev.h>
25 #include <linux/skbuff.h>
26 #include <linux/types.h>
27
28 #include "qca_7k_common.h"
29
30 #define QCAUART_DRV_VERSION "0.1.0"
31 #define QCAUART_DRV_NAME "qcauart"
32 #define QCAUART_TX_TIMEOUT (1 * HZ)
33
34 struct qcauart {
35 struct net_device *net_dev;
36 spinlock_t lock; /* transmit lock */
37 struct work_struct tx_work; /* Flushes transmit buffer */
38
39 struct serdev_device *serdev;
40 struct qcafrm_handle frm_handle;
41 struct sk_buff *rx_skb;
42
43 unsigned char *tx_head; /* pointer to next XMIT byte */
44 int tx_left; /* bytes left in XMIT queue */
45 unsigned char *tx_buffer;
46 };
47
48 static size_t
qca_tty_receive(struct serdev_device * serdev,const u8 * data,size_t count)49 qca_tty_receive(struct serdev_device *serdev, const u8 *data, size_t count)
50 {
51 struct qcauart *qca = serdev_device_get_drvdata(serdev);
52 struct net_device *netdev = qca->net_dev;
53 struct net_device_stats *n_stats = &netdev->stats;
54 size_t i;
55
56 if (!qca->rx_skb) {
57 qca->rx_skb = netdev_alloc_skb_ip_align(netdev,
58 netdev->mtu +
59 VLAN_ETH_HLEN);
60 if (!qca->rx_skb) {
61 n_stats->rx_errors++;
62 n_stats->rx_dropped++;
63 return 0;
64 }
65 }
66
67 for (i = 0; i < count; i++) {
68 s32 retcode;
69
70 retcode = qcafrm_fsm_decode(&qca->frm_handle,
71 qca->rx_skb->data,
72 skb_tailroom(qca->rx_skb),
73 data[i]);
74
75 switch (retcode) {
76 case QCAFRM_GATHER:
77 case QCAFRM_NOHEAD:
78 break;
79 case QCAFRM_NOTAIL:
80 netdev_dbg(netdev, "recv: no RX tail\n");
81 n_stats->rx_errors++;
82 n_stats->rx_dropped++;
83 break;
84 case QCAFRM_INVLEN:
85 netdev_dbg(netdev, "recv: invalid RX length\n");
86 n_stats->rx_errors++;
87 n_stats->rx_dropped++;
88 break;
89 default:
90 n_stats->rx_packets++;
91 n_stats->rx_bytes += retcode;
92 skb_put(qca->rx_skb, retcode);
93 qca->rx_skb->protocol = eth_type_trans(
94 qca->rx_skb, qca->rx_skb->dev);
95 skb_checksum_none_assert(qca->rx_skb);
96 netif_rx(qca->rx_skb);
97 qca->rx_skb = netdev_alloc_skb_ip_align(netdev,
98 netdev->mtu +
99 VLAN_ETH_HLEN);
100 if (!qca->rx_skb) {
101 netdev_dbg(netdev, "recv: out of RX resources\n");
102 n_stats->rx_errors++;
103 return i;
104 }
105 }
106 }
107
108 return i;
109 }
110
111 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
qcauart_transmit(struct work_struct * work)112 static void qcauart_transmit(struct work_struct *work)
113 {
114 struct qcauart *qca = container_of(work, struct qcauart, tx_work);
115 struct net_device_stats *n_stats = &qca->net_dev->stats;
116 int written;
117
118 spin_lock_bh(&qca->lock);
119
120 /* First make sure we're connected. */
121 if (!netif_running(qca->net_dev)) {
122 spin_unlock_bh(&qca->lock);
123 return;
124 }
125
126 if (qca->tx_left <= 0) {
127 /* Now serial buffer is almost free & we can start
128 * transmission of another packet
129 */
130 n_stats->tx_packets++;
131 spin_unlock_bh(&qca->lock);
132 netif_wake_queue(qca->net_dev);
133 return;
134 }
135
136 written = serdev_device_write_buf(qca->serdev, qca->tx_head,
137 qca->tx_left);
138 if (written > 0) {
139 qca->tx_left -= written;
140 qca->tx_head += written;
141 }
142 spin_unlock_bh(&qca->lock);
143 }
144
145 /* Called by the driver when there's room for more data.
146 * Schedule the transmit.
147 */
qca_tty_wakeup(struct serdev_device * serdev)148 static void qca_tty_wakeup(struct serdev_device *serdev)
149 {
150 struct qcauart *qca = serdev_device_get_drvdata(serdev);
151
152 schedule_work(&qca->tx_work);
153 }
154
155 static const struct serdev_device_ops qca_serdev_ops = {
156 .receive_buf = qca_tty_receive,
157 .write_wakeup = qca_tty_wakeup,
158 };
159
qcauart_netdev_open(struct net_device * dev)160 static int qcauart_netdev_open(struct net_device *dev)
161 {
162 struct qcauart *qca = netdev_priv(dev);
163
164 netif_start_queue(qca->net_dev);
165
166 return 0;
167 }
168
qcauart_netdev_close(struct net_device * dev)169 static int qcauart_netdev_close(struct net_device *dev)
170 {
171 struct qcauart *qca = netdev_priv(dev);
172
173 netif_stop_queue(dev);
174 flush_work(&qca->tx_work);
175
176 spin_lock_bh(&qca->lock);
177 qca->tx_left = 0;
178 spin_unlock_bh(&qca->lock);
179
180 return 0;
181 }
182
183 static netdev_tx_t
qcauart_netdev_xmit(struct sk_buff * skb,struct net_device * dev)184 qcauart_netdev_xmit(struct sk_buff *skb, struct net_device *dev)
185 {
186 struct net_device_stats *n_stats = &dev->stats;
187 struct qcauart *qca = netdev_priv(dev);
188 u8 pad_len = 0;
189 int written;
190 u8 *pos;
191
192 spin_lock(&qca->lock);
193
194 WARN_ON(qca->tx_left);
195
196 if (!netif_running(dev)) {
197 spin_unlock(&qca->lock);
198 netdev_warn(qca->net_dev, "xmit: iface is down\n");
199 goto out;
200 }
201
202 pos = qca->tx_buffer;
203
204 if (skb->len < QCAFRM_MIN_LEN)
205 pad_len = QCAFRM_MIN_LEN - skb->len;
206
207 pos += qcafrm_create_header(pos, skb->len + pad_len);
208
209 memcpy(pos, skb->data, skb->len);
210 pos += skb->len;
211
212 if (pad_len) {
213 memset(pos, 0, pad_len);
214 pos += pad_len;
215 }
216
217 pos += qcafrm_create_footer(pos);
218
219 netif_stop_queue(qca->net_dev);
220
221 written = serdev_device_write_buf(qca->serdev, qca->tx_buffer,
222 pos - qca->tx_buffer);
223 if (written > 0) {
224 qca->tx_left = (pos - qca->tx_buffer) - written;
225 qca->tx_head = qca->tx_buffer + written;
226 n_stats->tx_bytes += written;
227 }
228 spin_unlock(&qca->lock);
229
230 netif_trans_update(dev);
231 out:
232 dev_kfree_skb_any(skb);
233 return NETDEV_TX_OK;
234 }
235
qcauart_netdev_tx_timeout(struct net_device * dev,unsigned int txqueue)236 static void qcauart_netdev_tx_timeout(struct net_device *dev, unsigned int txqueue)
237 {
238 struct qcauart *qca = netdev_priv(dev);
239
240 netdev_info(qca->net_dev, "Transmit timeout at %ld, latency %ld\n",
241 jiffies, dev_trans_start(dev));
242 dev->stats.tx_errors++;
243 dev->stats.tx_dropped++;
244 }
245
qcauart_netdev_init(struct net_device * dev)246 static int qcauart_netdev_init(struct net_device *dev)
247 {
248 struct qcauart *qca = netdev_priv(dev);
249 size_t len;
250
251 /* Finish setting up the device info. */
252 dev->mtu = QCAFRM_MAX_MTU;
253 dev->type = ARPHRD_ETHER;
254
255 len = QCAFRM_HEADER_LEN + QCAFRM_MAX_LEN + QCAFRM_FOOTER_LEN;
256 qca->tx_buffer = devm_kmalloc(&qca->serdev->dev, len, GFP_KERNEL);
257 if (!qca->tx_buffer)
258 return -ENOMEM;
259
260 qca->rx_skb = netdev_alloc_skb_ip_align(qca->net_dev,
261 qca->net_dev->mtu +
262 VLAN_ETH_HLEN);
263 if (!qca->rx_skb)
264 return -ENOBUFS;
265
266 return 0;
267 }
268
qcauart_netdev_uninit(struct net_device * dev)269 static void qcauart_netdev_uninit(struct net_device *dev)
270 {
271 struct qcauart *qca = netdev_priv(dev);
272
273 dev_kfree_skb(qca->rx_skb);
274 }
275
276 static const struct net_device_ops qcauart_netdev_ops = {
277 .ndo_init = qcauart_netdev_init,
278 .ndo_uninit = qcauart_netdev_uninit,
279 .ndo_open = qcauart_netdev_open,
280 .ndo_stop = qcauart_netdev_close,
281 .ndo_start_xmit = qcauart_netdev_xmit,
282 .ndo_set_mac_address = eth_mac_addr,
283 .ndo_tx_timeout = qcauart_netdev_tx_timeout,
284 .ndo_validate_addr = eth_validate_addr,
285 };
286
qcauart_netdev_setup(struct net_device * dev)287 static void qcauart_netdev_setup(struct net_device *dev)
288 {
289 dev->netdev_ops = &qcauart_netdev_ops;
290 dev->watchdog_timeo = QCAUART_TX_TIMEOUT;
291 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
292 dev->tx_queue_len = 100;
293
294 /* MTU range: 46 - 1500 */
295 dev->min_mtu = QCAFRM_MIN_MTU;
296 dev->max_mtu = QCAFRM_MAX_MTU;
297 }
298
299 static const struct of_device_id qca_uart_of_match[] = {
300 {
301 .compatible = "qca,qca7000",
302 },
303 {}
304 };
305 MODULE_DEVICE_TABLE(of, qca_uart_of_match);
306
qca_uart_probe(struct serdev_device * serdev)307 static int qca_uart_probe(struct serdev_device *serdev)
308 {
309 struct net_device *qcauart_dev = alloc_etherdev(sizeof(struct qcauart));
310 struct qcauart *qca;
311 u32 speed = 115200;
312 int ret;
313
314 if (!qcauart_dev)
315 return -ENOMEM;
316
317 qcauart_netdev_setup(qcauart_dev);
318 SET_NETDEV_DEV(qcauart_dev, &serdev->dev);
319
320 qca = netdev_priv(qcauart_dev);
321 if (!qca) {
322 pr_err("qca_uart: Fail to retrieve private structure\n");
323 ret = -ENOMEM;
324 goto free;
325 }
326 qca->net_dev = qcauart_dev;
327 qca->serdev = serdev;
328 qcafrm_fsm_init_uart(&qca->frm_handle);
329
330 spin_lock_init(&qca->lock);
331 INIT_WORK(&qca->tx_work, qcauart_transmit);
332
333 of_property_read_u32(serdev->dev.of_node, "current-speed", &speed);
334
335 ret = of_get_ethdev_address(serdev->dev.of_node, qca->net_dev);
336 if (ret) {
337 eth_hw_addr_random(qca->net_dev);
338 dev_info(&serdev->dev, "Using random MAC address: %pM\n",
339 qca->net_dev->dev_addr);
340 }
341
342 netif_carrier_on(qca->net_dev);
343 serdev_device_set_drvdata(serdev, qca);
344 serdev_device_set_client_ops(serdev, &qca_serdev_ops);
345
346 ret = serdev_device_open(serdev);
347 if (ret) {
348 dev_err(&serdev->dev, "Unable to open device %s\n",
349 qcauart_dev->name);
350 goto free;
351 }
352
353 speed = serdev_device_set_baudrate(serdev, speed);
354 dev_info(&serdev->dev, "Using baudrate: %u\n", speed);
355
356 serdev_device_set_flow_control(serdev, false);
357
358 ret = register_netdev(qcauart_dev);
359 if (ret) {
360 dev_err(&serdev->dev, "Unable to register net device %s\n",
361 qcauart_dev->name);
362 serdev_device_close(serdev);
363 cancel_work_sync(&qca->tx_work);
364 goto free;
365 }
366
367 return 0;
368
369 free:
370 free_netdev(qcauart_dev);
371 return ret;
372 }
373
qca_uart_remove(struct serdev_device * serdev)374 static void qca_uart_remove(struct serdev_device *serdev)
375 {
376 struct qcauart *qca = serdev_device_get_drvdata(serdev);
377
378 unregister_netdev(qca->net_dev);
379
380 /* Flush any pending characters in the driver. */
381 serdev_device_close(serdev);
382 cancel_work_sync(&qca->tx_work);
383
384 free_netdev(qca->net_dev);
385 }
386
387 static struct serdev_device_driver qca_uart_driver = {
388 .probe = qca_uart_probe,
389 .remove = qca_uart_remove,
390 .driver = {
391 .name = QCAUART_DRV_NAME,
392 .of_match_table = qca_uart_of_match,
393 },
394 };
395
396 module_serdev_device_driver(qca_uart_driver);
397
398 MODULE_DESCRIPTION("Qualcomm Atheros QCA7000 UART Driver");
399 MODULE_AUTHOR("Qualcomm Atheros Communications");
400 MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net>");
401 MODULE_LICENSE("Dual BSD/GPL");
402 MODULE_VERSION(QCAUART_DRV_VERSION);
403