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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) ST-Ericsson AB 20104 * Author: Sjur Brendeland5 */6 7#include <linux/hardirq.h>8#include <linux/init.h>9#include <linux/module.h>10#include <linux/device.h>11#include <linux/types.h>12#include <linux/skbuff.h>13#include <linux/netdevice.h>14#include <linux/rtnetlink.h>15#include <linux/tty.h>16#include <linux/file.h>17#include <linux/if_arp.h>18#include <net/caif/caif_device.h>19#include <net/caif/cfcnfg.h>20#include <linux/err.h>21#include <linux/debugfs.h>22 23MODULE_LICENSE("GPL");24MODULE_AUTHOR("Sjur Brendeland");25MODULE_DESCRIPTION("CAIF serial device TTY line discipline");26MODULE_LICENSE("GPL");27MODULE_ALIAS_LDISC(N_CAIF);28 29#define SEND_QUEUE_LOW 1030#define SEND_QUEUE_HIGH 10031#define CAIF_SENDING 1 /* Bit 1 = 0x02*/32#define CAIF_FLOW_OFF_SENT 4 /* Bit 4 = 0x10 */33#define MAX_WRITE_CHUNK 409634#define ON 135#define OFF 036#define CAIF_MAX_MTU 409637 38static DEFINE_SPINLOCK(ser_lock);39static LIST_HEAD(ser_list);40static LIST_HEAD(ser_release_list);41 42static bool ser_loop;43module_param(ser_loop, bool, 0444);44MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode.");45 46static bool ser_use_stx = true;47module_param(ser_use_stx, bool, 0444);48MODULE_PARM_DESC(ser_use_stx, "STX enabled or not.");49 50static bool ser_use_fcs = true;51 52module_param(ser_use_fcs, bool, 0444);53MODULE_PARM_DESC(ser_use_fcs, "FCS enabled or not.");54 55static int ser_write_chunk = MAX_WRITE_CHUNK;56module_param(ser_write_chunk, int, 0444);57 58MODULE_PARM_DESC(ser_write_chunk, "Maximum size of data written to UART.");59 60static struct dentry *debugfsdir;61 62static int caif_net_open(struct net_device *dev);63static int caif_net_close(struct net_device *dev);64 65struct ser_device {66 struct caif_dev_common common;67 struct list_head node;68 struct net_device *dev;69 struct sk_buff_head head;70 struct tty_struct *tty;71 bool tx_started;72 unsigned long state;73#ifdef CONFIG_DEBUG_FS74 struct dentry *debugfs_tty_dir;75 struct debugfs_blob_wrapper tx_blob;76 struct debugfs_blob_wrapper rx_blob;77 u8 rx_data[128];78 u8 tx_data[128];79 u8 tty_status;80 81#endif82};83 84static void caifdev_setup(struct net_device *dev);85static void ldisc_tx_wakeup(struct tty_struct *tty);86#ifdef CONFIG_DEBUG_FS87static inline void update_tty_status(struct ser_device *ser)88{89 ser->tty_status =90 ser->tty->flow.stopped << 5 |91 ser->tty->flow.tco_stopped << 3 |92 ser->tty->ctrl.packet << 2;93}94static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)95{96 ser->debugfs_tty_dir = debugfs_create_dir(tty->name, debugfsdir);97 98 debugfs_create_blob("last_tx_msg", 0400, ser->debugfs_tty_dir,99 &ser->tx_blob);100 101 debugfs_create_blob("last_rx_msg", 0400, ser->debugfs_tty_dir,102 &ser->rx_blob);103 104 debugfs_create_xul("ser_state", 0400, ser->debugfs_tty_dir,105 &ser->state);106 107 debugfs_create_x8("tty_status", 0400, ser->debugfs_tty_dir,108 &ser->tty_status);109 110 ser->tx_blob.data = ser->tx_data;111 ser->tx_blob.size = 0;112 ser->rx_blob.data = ser->rx_data;113 ser->rx_blob.size = 0;114}115 116static inline void debugfs_deinit(struct ser_device *ser)117{118 debugfs_remove_recursive(ser->debugfs_tty_dir);119}120 121static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)122{123 if (size > sizeof(ser->rx_data))124 size = sizeof(ser->rx_data);125 memcpy(ser->rx_data, data, size);126 ser->rx_blob.data = ser->rx_data;127 ser->rx_blob.size = size;128}129 130static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)131{132 if (size > sizeof(ser->tx_data))133 size = sizeof(ser->tx_data);134 memcpy(ser->tx_data, data, size);135 ser->tx_blob.data = ser->tx_data;136 ser->tx_blob.size = size;137}138#else139static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)140{141}142 143static inline void debugfs_deinit(struct ser_device *ser)144{145}146 147static inline void update_tty_status(struct ser_device *ser)148{149}150 151static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)152{153}154 155static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)156{157}158 159#endif160 161static void ldisc_receive(struct tty_struct *tty, const u8 *data,162 const u8 *flags, size_t count)163{164 struct sk_buff *skb = NULL;165 struct ser_device *ser;166 int ret;167 168 ser = tty->disc_data;169 170 /*171 * NOTE: flags may contain information about break or overrun.172 * This is not yet handled.173 */174 175 176 /*177 * Workaround for garbage at start of transmission,178 * only enable if STX handling is not enabled.179 */180 if (!ser->common.use_stx && !ser->tx_started) {181 dev_info(&ser->dev->dev,182 "Bytes received before initial transmission -"183 "bytes discarded.\n");184 return;185 }186 187 BUG_ON(ser->dev == NULL);188 189 /* Get a suitable caif packet and copy in data. */190 skb = netdev_alloc_skb(ser->dev, count+1);191 if (skb == NULL)192 return;193 skb_put_data(skb, data, count);194 195 skb->protocol = htons(ETH_P_CAIF);196 skb_reset_mac_header(skb);197 debugfs_rx(ser, data, count);198 /* Push received packet up the stack. */199 ret = netif_rx(skb);200 if (!ret) {201 ser->dev->stats.rx_packets++;202 ser->dev->stats.rx_bytes += count;203 } else204 ++ser->dev->stats.rx_dropped;205 update_tty_status(ser);206}207 208static int handle_tx(struct ser_device *ser)209{210 struct tty_struct *tty;211 struct sk_buff *skb;212 int tty_wr, len, room;213 214 tty = ser->tty;215 ser->tx_started = true;216 217 /* Enter critical section */218 if (test_and_set_bit(CAIF_SENDING, &ser->state))219 return 0;220 221 /* skb_peek is safe because handle_tx is called after skb_queue_tail */222 while ((skb = skb_peek(&ser->head)) != NULL) {223 224 /* Make sure you don't write too much */225 len = skb->len;226 room = tty_write_room(tty);227 if (!room)228 break;229 if (room > ser_write_chunk)230 room = ser_write_chunk;231 if (len > room)232 len = room;233 234 /* Write to tty or loopback */235 if (!ser_loop) {236 tty_wr = tty->ops->write(tty, skb->data, len);237 update_tty_status(ser);238 } else {239 tty_wr = len;240 ldisc_receive(tty, skb->data, NULL, len);241 }242 ser->dev->stats.tx_packets++;243 ser->dev->stats.tx_bytes += tty_wr;244 245 /* Error on TTY ?! */246 if (tty_wr < 0)247 goto error;248 /* Reduce buffer written, and discard if empty */249 skb_pull(skb, tty_wr);250 if (skb->len == 0) {251 struct sk_buff *tmp = skb_dequeue(&ser->head);252 WARN_ON(tmp != skb);253 dev_consume_skb_any(skb);254 }255 }256 /* Send flow off if queue is empty */257 if (ser->head.qlen <= SEND_QUEUE_LOW &&258 test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&259 ser->common.flowctrl != NULL)260 ser->common.flowctrl(ser->dev, ON);261 clear_bit(CAIF_SENDING, &ser->state);262 return 0;263error:264 clear_bit(CAIF_SENDING, &ser->state);265 return tty_wr;266}267 268static netdev_tx_t caif_xmit(struct sk_buff *skb, struct net_device *dev)269{270 struct ser_device *ser;271 272 ser = netdev_priv(dev);273 274 /* Send flow off once, on high water mark */275 if (ser->head.qlen > SEND_QUEUE_HIGH &&276 !test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&277 ser->common.flowctrl != NULL)278 279 ser->common.flowctrl(ser->dev, OFF);280 281 skb_queue_tail(&ser->head, skb);282 return handle_tx(ser);283}284 285 286static void ldisc_tx_wakeup(struct tty_struct *tty)287{288 struct ser_device *ser;289 290 ser = tty->disc_data;291 BUG_ON(ser == NULL);292 WARN_ON(ser->tty != tty);293 handle_tx(ser);294}295 296 297static void ser_release(struct work_struct *work)298{299 struct list_head list;300 struct ser_device *ser, *tmp;301 302 spin_lock(&ser_lock);303 list_replace_init(&ser_release_list, &list);304 spin_unlock(&ser_lock);305 306 if (!list_empty(&list)) {307 rtnl_lock();308 list_for_each_entry_safe(ser, tmp, &list, node) {309 dev_close(ser->dev);310 unregister_netdevice(ser->dev);311 debugfs_deinit(ser);312 }313 rtnl_unlock();314 }315}316 317static DECLARE_WORK(ser_release_work, ser_release);318 319static int ldisc_open(struct tty_struct *tty)320{321 struct ser_device *ser;322 struct net_device *dev;323 char name[64];324 int result;325 326 /* No write no play */327 if (tty->ops->write == NULL)328 return -EOPNOTSUPP;329 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG))330 return -EPERM;331 332 /* release devices to avoid name collision */333 ser_release(NULL);334 335 result = snprintf(name, sizeof(name), "cf%s", tty->name);336 if (result >= IFNAMSIZ)337 return -EINVAL;338 dev = alloc_netdev(sizeof(*ser), name, NET_NAME_UNKNOWN,339 caifdev_setup);340 if (!dev)341 return -ENOMEM;342 343 ser = netdev_priv(dev);344 ser->tty = tty_kref_get(tty);345 ser->dev = dev;346 debugfs_init(ser, tty);347 tty->receive_room = N_TTY_BUF_SIZE;348 tty->disc_data = ser;349 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);350 rtnl_lock();351 result = register_netdevice(dev);352 if (result) {353 tty_kref_put(tty);354 rtnl_unlock();355 free_netdev(dev);356 return -ENODEV;357 }358 359 spin_lock(&ser_lock);360 list_add(&ser->node, &ser_list);361 spin_unlock(&ser_lock);362 rtnl_unlock();363 netif_stop_queue(dev);364 update_tty_status(ser);365 return 0;366}367 368static void ldisc_close(struct tty_struct *tty)369{370 struct ser_device *ser = tty->disc_data;371 372 tty_kref_put(ser->tty);373 374 spin_lock(&ser_lock);375 list_move(&ser->node, &ser_release_list);376 spin_unlock(&ser_lock);377 schedule_work(&ser_release_work);378}379 380/* The line discipline structure. */381static struct tty_ldisc_ops caif_ldisc = {382 .owner = THIS_MODULE,383 .num = N_CAIF,384 .name = "n_caif",385 .open = ldisc_open,386 .close = ldisc_close,387 .receive_buf = ldisc_receive,388 .write_wakeup = ldisc_tx_wakeup389};390 391static const struct net_device_ops netdev_ops = {392 .ndo_open = caif_net_open,393 .ndo_stop = caif_net_close,394 .ndo_start_xmit = caif_xmit395};396 397static void caifdev_setup(struct net_device *dev)398{399 struct ser_device *serdev = netdev_priv(dev);400 401 dev->features = 0;402 dev->netdev_ops = &netdev_ops;403 dev->type = ARPHRD_CAIF;404 dev->flags = IFF_POINTOPOINT | IFF_NOARP;405 dev->mtu = CAIF_MAX_MTU;406 dev->priv_flags |= IFF_NO_QUEUE;407 dev->needs_free_netdev = true;408 skb_queue_head_init(&serdev->head);409 serdev->common.link_select = CAIF_LINK_LOW_LATENCY;410 serdev->common.use_frag = true;411 serdev->common.use_stx = ser_use_stx;412 serdev->common.use_fcs = ser_use_fcs;413 serdev->dev = dev;414}415 416 417static int caif_net_open(struct net_device *dev)418{419 netif_wake_queue(dev);420 return 0;421}422 423static int caif_net_close(struct net_device *dev)424{425 netif_stop_queue(dev);426 return 0;427}428 429static int __init caif_ser_init(void)430{431 int ret;432 433 ret = tty_register_ldisc(&caif_ldisc);434 if (ret < 0)435 pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF, ret);436 437 debugfsdir = debugfs_create_dir("caif_serial", NULL);438 return ret;439}440 441static void __exit caif_ser_exit(void)442{443 spin_lock(&ser_lock);444 list_splice(&ser_list, &ser_release_list);445 spin_unlock(&ser_lock);446 ser_release(NULL);447 cancel_work_sync(&ser_release_work);448 tty_unregister_ldisc(&caif_ldisc);449 debugfs_remove_recursive(debugfsdir);450}451 452module_init(caif_ser_init);453module_exit(caif_ser_exit);454