summaryrefslogtreecommitdiff
path: root/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c
blob: 57304a5adf68e07e11893c364a00b51163e22827 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020-21 Intel Corporation.
 */

#include <linux/delay.h>

#include "iosm_ipc_chnl_cfg.h"
#include "iosm_ipc_devlink.h"
#include "iosm_ipc_imem.h"
#include "iosm_ipc_imem_ops.h"
#include "iosm_ipc_port.h"
#include "iosm_ipc_task_queue.h"

/* Open a packet data online channel between the network layer and CP. */
int ipc_imem_sys_wwan_open(struct iosm_imem *ipc_imem, int if_id)
{
	dev_dbg(ipc_imem->dev, "%s if id: %d",
		ipc_imem_phase_get_string(ipc_imem->phase), if_id);

	/* The network interface is only supported in the runtime phase. */
	if (ipc_imem_phase_update(ipc_imem) != IPC_P_RUN) {
		dev_err(ipc_imem->dev, "net:%d : refused phase %s", if_id,
			ipc_imem_phase_get_string(ipc_imem->phase));
		return -EIO;
	}

	return ipc_mux_open_session(ipc_imem->mux, if_id);
}

/* Release a net link to CP. */
void ipc_imem_sys_wwan_close(struct iosm_imem *ipc_imem, int if_id,
			     int channel_id)
{
	if (ipc_imem->mux && if_id >= IP_MUX_SESSION_START &&
	    if_id <= IP_MUX_SESSION_END)
		ipc_mux_close_session(ipc_imem->mux, if_id);
}

/* Tasklet call to do uplink transfer. */
static int ipc_imem_tq_cdev_write(struct iosm_imem *ipc_imem, int arg,
				  void *msg, size_t size)
{
	ipc_imem_ul_send(ipc_imem);

	return 0;
}

/* Through tasklet to do sio write. */
static int ipc_imem_call_cdev_write(struct iosm_imem *ipc_imem)
{
	return ipc_task_queue_send_task(ipc_imem, ipc_imem_tq_cdev_write, 0,
					NULL, 0, false);
}

/* Function for transfer UL data */
int ipc_imem_sys_wwan_transmit(struct iosm_imem *ipc_imem,
			       int if_id, int channel_id, struct sk_buff *skb)
{
	int ret = -EINVAL;

	if (!ipc_imem || channel_id < 0)
		goto out;

	/* Is CP Running? */
	if (ipc_imem->phase != IPC_P_RUN) {
		dev_dbg(ipc_imem->dev, "phase %s transmit",
			ipc_imem_phase_get_string(ipc_imem->phase));
		ret = -EIO;
		goto out;
	}

	/* Route the UL packet through IP MUX Layer */
	ret = ipc_mux_ul_trigger_encode(ipc_imem->mux, if_id, skb);
out:
	return ret;
}

/* Initialize wwan channel */
void ipc_imem_wwan_channel_init(struct iosm_imem *ipc_imem,
				enum ipc_mux_protocol mux_type)
{
	struct ipc_chnl_cfg chnl_cfg = { 0 };

	ipc_imem->cp_version = ipc_mmio_get_cp_version(ipc_imem->mmio);

	/* If modem version is invalid (0xffffffff), do not initialize WWAN. */
	if (ipc_imem->cp_version == -1) {
		dev_err(ipc_imem->dev, "invalid CP version");
		return;
	}

	ipc_chnl_cfg_get(&chnl_cfg, ipc_imem->nr_of_channels);
	ipc_imem_channel_init(ipc_imem, IPC_CTYPE_WWAN, chnl_cfg,
			      IRQ_MOD_OFF);

	/* WWAN registration. */
	ipc_imem->wwan = ipc_wwan_init(ipc_imem, ipc_imem->dev);
	if (!ipc_imem->wwan)
		dev_err(ipc_imem->dev,
			"failed to register the ipc_wwan interfaces");
}

/* Map SKB to DMA for transfer */
static int ipc_imem_map_skb_to_dma(struct iosm_imem *ipc_imem,
				   struct sk_buff *skb)
{
	struct iosm_pcie *ipc_pcie = ipc_imem->pcie;
	char *buf = skb->data;
	int len = skb->len;
	dma_addr_t mapping;
	int ret;

	ret = ipc_pcie_addr_map(ipc_pcie, buf, len, &mapping, DMA_TO_DEVICE);

	if (ret)
		goto err;

	BUILD_BUG_ON(sizeof(*IPC_CB(skb)) > sizeof(skb->cb));

	IPC_CB(skb)->mapping = mapping;
	IPC_CB(skb)->direction = DMA_TO_DEVICE;
	IPC_CB(skb)->len = len;
	IPC_CB(skb)->op_type = (u8)UL_DEFAULT;

err:
	return ret;
}

/* return true if channel is ready for use */
static bool ipc_imem_is_channel_active(struct iosm_imem *ipc_imem,
				       struct ipc_mem_channel *channel)
{
	enum ipc_phase phase;

	/* Update the current operation phase. */
	phase = ipc_imem->phase;

	/* Select the operation depending on the execution stage. */
	switch (phase) {
	case IPC_P_RUN:
	case IPC_P_PSI:
	case IPC_P_EBL:
		break;

	case IPC_P_ROM:
		/* Prepare the PSI image for the CP ROM driver and
		 * suspend the flash app.
		 */
		if (channel->state != IMEM_CHANNEL_RESERVED) {
			dev_err(ipc_imem->dev,
				"ch[%d]:invalid channel state %d,expected %d",
				channel->channel_id, channel->state,
				IMEM_CHANNEL_RESERVED);
			goto channel_unavailable;
		}
		goto channel_available;

	default:
		/* Ignore uplink actions in all other phases. */
		dev_err(ipc_imem->dev, "ch[%d]: confused phase %d",
			channel->channel_id, phase);
		goto channel_unavailable;
	}
	/* Check the full availability of the channel. */
	if (channel->state != IMEM_CHANNEL_ACTIVE) {
		dev_err(ipc_imem->dev, "ch[%d]: confused channel state %d",
			channel->channel_id, channel->state);
		goto channel_unavailable;
	}

channel_available:
	return true;

channel_unavailable:
	return false;
}

/**
 * ipc_imem_sys_port_close - Release a sio link to CP.
 * @ipc_imem:          Imem instance.
 * @channel:           Channel instance.
 */
void ipc_imem_sys_port_close(struct iosm_imem *ipc_imem,
			     struct ipc_mem_channel *channel)
{
	enum ipc_phase curr_phase;
	int status = 0;
	u32 tail = 0;

	curr_phase = ipc_imem->phase;

	/* If current phase is IPC_P_OFF or SIO ID is -ve then
	 * channel is already freed. Nothing to do.
	 */
	if (curr_phase == IPC_P_OFF) {
		dev_err(ipc_imem->dev,
			"nothing to do. Current Phase: %s",
			ipc_imem_phase_get_string(curr_phase));
		return;
	}

	if (channel->state == IMEM_CHANNEL_FREE) {
		dev_err(ipc_imem->dev, "ch[%d]: invalid channel state %d",
			channel->channel_id, channel->state);
		return;
	}

	/* If there are any pending TDs then wait for Timeout/Completion before
	 * closing pipe.
	 */
	if (channel->ul_pipe.old_tail != channel->ul_pipe.old_head) {
		ipc_imem->app_notify_ul_pend = 1;

		/* Suspend the user app and wait a certain time for processing
		 * UL Data.
		 */
		status = wait_for_completion_interruptible_timeout
			 (&ipc_imem->ul_pend_sem,
			  msecs_to_jiffies(IPC_PEND_DATA_TIMEOUT));
		if (status == 0) {
			dev_dbg(ipc_imem->dev,
				"Pend data Timeout UL-Pipe:%d Head:%d Tail:%d",
				channel->ul_pipe.pipe_nr,
				channel->ul_pipe.old_head,
				channel->ul_pipe.old_tail);
		}

		ipc_imem->app_notify_ul_pend = 0;
	}

	/* If there are any pending TDs then wait for Timeout/Completion before
	 * closing pipe.
	 */
	ipc_protocol_get_head_tail_index(ipc_imem->ipc_protocol,
					 &channel->dl_pipe, NULL, &tail);

	if (tail != channel->dl_pipe.old_tail) {
		ipc_imem->app_notify_dl_pend = 1;

		/* Suspend the user app and wait a certain time for processing
		 * DL Data.
		 */
		status = wait_for_completion_interruptible_timeout
			 (&ipc_imem->dl_pend_sem,
			  msecs_to_jiffies(IPC_PEND_DATA_TIMEOUT));
		if (status == 0) {
			dev_dbg(ipc_imem->dev,
				"Pend data Timeout DL-Pipe:%d Head:%d Tail:%d",
				channel->dl_pipe.pipe_nr,
				channel->dl_pipe.old_head,
				channel->dl_pipe.old_tail);
		}

		ipc_imem->app_notify_dl_pend = 0;
	}

	/* Due to wait for completion in messages, there is a small window
	 * between closing the pipe and updating the channel is closed. In this
	 * small window there could be HP update from Host Driver. Hence update
	 * the channel state as CLOSING to aviod unnecessary interrupt
	 * towards CP.
	 */
	channel->state = IMEM_CHANNEL_CLOSING;

	ipc_imem_pipe_close(ipc_imem, &channel->ul_pipe);
	ipc_imem_pipe_close(ipc_imem, &channel->dl_pipe);

	ipc_imem_channel_free(channel);
}

/* Open a PORT link to CP and return the channel */
struct ipc_mem_channel *ipc_imem_sys_port_open(struct iosm_imem *ipc_imem,
					       int chl_id, int hp_id)
{
	struct ipc_mem_channel *channel;
	int ch_id;

	/* The PORT interface is only supported in the runtime phase. */
	if (ipc_imem_phase_update(ipc_imem) != IPC_P_RUN) {
		dev_err(ipc_imem->dev, "PORT open refused, phase %s",
			ipc_imem_phase_get_string(ipc_imem->phase));
		return NULL;
	}

	ch_id = ipc_imem_channel_alloc(ipc_imem, chl_id, IPC_CTYPE_CTRL);

	if (ch_id < 0) {
		dev_err(ipc_imem->dev, "reservation of an PORT chnl id failed");
		return NULL;
	}

	channel = ipc_imem_channel_open(ipc_imem, ch_id, hp_id);

	if (!channel) {
		dev_err(ipc_imem->dev, "PORT channel id open failed");
		return NULL;
	}

	return channel;
}

/* transfer skb to modem */
int ipc_imem_sys_cdev_write(struct iosm_cdev *ipc_cdev, struct sk_buff *skb)
{
	struct ipc_mem_channel *channel = ipc_cdev->channel;
	struct iosm_imem *ipc_imem = ipc_cdev->ipc_imem;
	int ret = -EIO;

	if (!ipc_imem_is_channel_active(ipc_imem, channel) ||
	    ipc_imem->phase == IPC_P_OFF_REQ)
		goto out;

	ret = ipc_imem_map_skb_to_dma(ipc_imem, skb);

	if (ret)
		goto out;

	/* Add skb to the uplink skbuf accumulator. */
	skb_queue_tail(&channel->ul_list, skb);

	ret = ipc_imem_call_cdev_write(ipc_imem);

	if (ret) {
		skb_dequeue_tail(&channel->ul_list);
		dev_err(ipc_cdev->dev, "channel id[%d] write failed\n",
			ipc_cdev->channel->channel_id);
	}
out:
	return ret;
}

/* Open a SIO link to CP and return the channel instance */
struct ipc_mem_channel *ipc_imem_sys_devlink_open(struct iosm_imem *ipc_imem)
{
	struct ipc_mem_channel *channel;
	enum ipc_phase phase;
	int channel_id;

	phase = ipc_imem_phase_update(ipc_imem);
	switch (phase) {
	case IPC_P_OFF:
	case IPC_P_ROM:
		/* Get a channel id as flash id and reserve it. */
		channel_id = ipc_imem_channel_alloc(ipc_imem,
						    IPC_MEM_CTRL_CHL_ID_7,
						    IPC_CTYPE_CTRL);

		if (channel_id < 0) {
			dev_err(ipc_imem->dev,
				"reservation of a flash channel id failed");
			goto error;
		}

		ipc_imem->ipc_devlink->devlink_sio.channel_id = channel_id;
		channel = &ipc_imem->channels[channel_id];

		/* Enqueue chip info data to be read */
		if (ipc_imem_devlink_trigger_chip_info(ipc_imem)) {
			dev_err(ipc_imem->dev, "Enqueue of chip info failed");
			channel->state = IMEM_CHANNEL_FREE;
			goto error;
		}

		return channel;

	case IPC_P_PSI:
	case IPC_P_EBL:
		ipc_imem->cp_version = ipc_mmio_get_cp_version(ipc_imem->mmio);
		if (ipc_imem->cp_version == -1) {
			dev_err(ipc_imem->dev, "invalid CP version");
			goto error;
		}

		channel_id = ipc_imem->ipc_devlink->devlink_sio.channel_id;
		return ipc_imem_channel_open(ipc_imem, channel_id,
					     IPC_HP_CDEV_OPEN);

	default:
		/* CP is in the wrong state (e.g. CRASH or CD_READY) */
		dev_err(ipc_imem->dev, "SIO open refused, phase %d", phase);
	}
error:
	return NULL;
}

/* Release a SIO channel link to CP. */
void ipc_imem_sys_devlink_close(struct iosm_devlink *ipc_devlink)
{
	struct iosm_imem *ipc_imem = ipc_devlink->pcie->imem;
	int boot_check_timeout = BOOT_CHECK_DEFAULT_TIMEOUT;
	enum ipc_mem_exec_stage exec_stage;
	struct ipc_mem_channel *channel;
	int status = 0;
	u32 tail = 0;

	channel = ipc_imem->ipc_devlink->devlink_sio.channel;
	/* Increase the total wait time to boot_check_timeout */
	do {
		exec_stage = ipc_mmio_get_exec_stage(ipc_imem->mmio);
		if (exec_stage == IPC_MEM_EXEC_STAGE_RUN ||
		    exec_stage == IPC_MEM_EXEC_STAGE_PSI)
			break;
		msleep(20);
		boot_check_timeout -= 20;
	} while (boot_check_timeout > 0);

	/* If there are any pending TDs then wait for Timeout/Completion before
	 * closing pipe.
	 */
	if (channel->ul_pipe.old_tail != channel->ul_pipe.old_head) {
		status = wait_for_completion_interruptible_timeout
			(&ipc_imem->ul_pend_sem,
			 msecs_to_jiffies(IPC_PEND_DATA_TIMEOUT));
		if (status == 0) {
			dev_dbg(ipc_imem->dev,
				"Data Timeout on UL-Pipe:%d Head:%d Tail:%d",
				channel->ul_pipe.pipe_nr,
				channel->ul_pipe.old_head,
				channel->ul_pipe.old_tail);
		}
	}

	ipc_protocol_get_head_tail_index(ipc_imem->ipc_protocol,
					 &channel->dl_pipe, NULL, &tail);

	if (tail != channel->dl_pipe.old_tail) {
		status = wait_for_completion_interruptible_timeout
			(&ipc_imem->dl_pend_sem,
			 msecs_to_jiffies(IPC_PEND_DATA_TIMEOUT));
		if (status == 0) {
			dev_dbg(ipc_imem->dev,
				"Data Timeout on DL-Pipe:%d Head:%d Tail:%d",
				channel->dl_pipe.pipe_nr,
				channel->dl_pipe.old_head,
				channel->dl_pipe.old_tail);
		}
	}

	/* Due to wait for completion in messages, there is a small window
	 * between closing the pipe and updating the channel is closed. In this
	 * small window there could be HP update from Host Driver. Hence update
	 * the channel state as CLOSING to aviod unnecessary interrupt
	 * towards CP.
	 */
	channel->state = IMEM_CHANNEL_CLOSING;
	/* Release the pipe resources */
	ipc_imem_pipe_cleanup(ipc_imem, &channel->ul_pipe);
	ipc_imem_pipe_cleanup(ipc_imem, &channel->dl_pipe);
	ipc_imem->nr_of_channels--;
}

void ipc_imem_sys_devlink_notify_rx(struct iosm_devlink *ipc_devlink,
				    struct sk_buff *skb)
{
	skb_queue_tail(&ipc_devlink->devlink_sio.rx_list, skb);
	complete(&ipc_devlink->devlink_sio.read_sem);
}

/* PSI transfer */
static int ipc_imem_sys_psi_transfer(struct iosm_imem *ipc_imem,
				     struct ipc_mem_channel *channel,
				     unsigned char *buf, int count)
{
	int psi_start_timeout = PSI_START_DEFAULT_TIMEOUT;
	enum ipc_mem_exec_stage exec_stage;

	dma_addr_t mapping = 0;
	int ret;

	ret = ipc_pcie_addr_map(ipc_imem->pcie, buf, count, &mapping,
				DMA_TO_DEVICE);
	if (ret)
		goto pcie_addr_map_fail;

	/* Save the PSI information for the CP ROM driver on the doorbell
	 * scratchpad.
	 */
	ipc_mmio_set_psi_addr_and_size(ipc_imem->mmio, mapping, count);
	ipc_doorbell_fire(ipc_imem->pcie, 0, IPC_MEM_EXEC_STAGE_BOOT);

	ret = wait_for_completion_interruptible_timeout
		(&channel->ul_sem,
		 msecs_to_jiffies(IPC_PSI_TRANSFER_TIMEOUT));

	if (ret <= 0) {
		dev_err(ipc_imem->dev, "Failed PSI transfer to CP, Error-%d",
			ret);
		goto psi_transfer_fail;
	}
	/* If the PSI download fails, return the CP boot ROM exit code */
	if (ipc_imem->rom_exit_code != IMEM_ROM_EXIT_OPEN_EXT &&
	    ipc_imem->rom_exit_code != IMEM_ROM_EXIT_CERT_EXT) {
		ret = (-1) * ((int)ipc_imem->rom_exit_code);
		goto psi_transfer_fail;
	}

	dev_dbg(ipc_imem->dev, "PSI image successfully downloaded");

	/* Wait psi_start_timeout milliseconds until the CP PSI image is
	 * running and updates the execution_stage field with
	 * IPC_MEM_EXEC_STAGE_PSI. Verify the execution stage.
	 */
	do {
		exec_stage = ipc_mmio_get_exec_stage(ipc_imem->mmio);

		if (exec_stage == IPC_MEM_EXEC_STAGE_PSI)
			break;

		msleep(20);
		psi_start_timeout -= 20;
	} while (psi_start_timeout > 0);

	if (exec_stage != IPC_MEM_EXEC_STAGE_PSI)
		goto psi_transfer_fail; /* Unknown status of CP PSI process. */

	ipc_imem->phase = IPC_P_PSI;

	/* Enter the PSI phase. */
	dev_dbg(ipc_imem->dev, "execution_stage[%X] eq. PSI", exec_stage);

	/* Request the RUNNING state from CP and wait until it was reached
	 * or timeout.
	 */
	ipc_imem_ipc_init_check(ipc_imem);

	ret = wait_for_completion_interruptible_timeout
		(&channel->ul_sem, msecs_to_jiffies(IPC_PSI_TRANSFER_TIMEOUT));
	if (ret <= 0) {
		dev_err(ipc_imem->dev,
			"Failed PSI RUNNING state on CP, Error-%d", ret);
		goto psi_transfer_fail;
	}

	if (ipc_mmio_get_ipc_state(ipc_imem->mmio) !=
			IPC_MEM_DEVICE_IPC_RUNNING) {
		dev_err(ipc_imem->dev,
			"ch[%d] %s: unexpected CP IPC state %d, not RUNNING",
			channel->channel_id,
			ipc_imem_phase_get_string(ipc_imem->phase),
			ipc_mmio_get_ipc_state(ipc_imem->mmio));

		goto psi_transfer_fail;
	}

	/* Create the flash channel for the transfer of the images. */
	if (!ipc_imem_sys_devlink_open(ipc_imem)) {
		dev_err(ipc_imem->dev, "can't open flash_channel");
		goto psi_transfer_fail;
	}

	ret = 0;
psi_transfer_fail:
	ipc_pcie_addr_unmap(ipc_imem->pcie, count, mapping, DMA_TO_DEVICE);
pcie_addr_map_fail:
	return ret;
}

int ipc_imem_sys_devlink_write(struct iosm_devlink *ipc_devlink,
			       unsigned char *buf, int count)
{
	struct iosm_imem *ipc_imem = ipc_devlink->pcie->imem;
	struct ipc_mem_channel *channel;
	struct sk_buff *skb;
	dma_addr_t mapping;
	int ret;

	channel = ipc_imem->ipc_devlink->devlink_sio.channel;

	/* In the ROM phase the PSI image is passed to CP about a specific
	 *  shared memory area and doorbell scratchpad directly.
	 */
	if (ipc_imem->phase == IPC_P_ROM) {
		ret = ipc_imem_sys_psi_transfer(ipc_imem, channel, buf, count);
		/* If the PSI transfer fails then send crash
		 * Signature.
		 */
		if (ret > 0)
			ipc_imem_msg_send_feature_set(ipc_imem,
						      IPC_MEM_INBAND_CRASH_SIG,
						      false);
		goto out;
	}

	/* Allocate skb memory for the uplink buffer. */
	skb = ipc_pcie_alloc_skb(ipc_devlink->pcie, count, GFP_KERNEL, &mapping,
				 DMA_TO_DEVICE, 0);
	if (!skb) {
		ret = -ENOMEM;
		goto out;
	}

	memcpy(skb_put(skb, count), buf, count);

	IPC_CB(skb)->op_type = UL_USR_OP_BLOCKED;

	/* Add skb to the uplink skbuf accumulator. */
	skb_queue_tail(&channel->ul_list, skb);

	/* Inform the IPC tasklet to pass uplink IP packets to CP. */
	if (!ipc_imem_call_cdev_write(ipc_imem)) {
		ret = wait_for_completion_interruptible(&channel->ul_sem);

		if (ret < 0) {
			dev_err(ipc_imem->dev,
				"ch[%d] no CP confirmation, status = %d",
				channel->channel_id, ret);
			ipc_pcie_kfree_skb(ipc_devlink->pcie, skb);
			goto out;
		}
	}
	ret = 0;
out:
	return ret;
}

int ipc_imem_sys_devlink_read(struct iosm_devlink *devlink, u8 *data,
			      u32 bytes_to_read, u32 *bytes_read)
{
	struct sk_buff *skb = NULL;
	int rc = 0;

	/* check skb is available in rx_list or wait for skb */
	devlink->devlink_sio.devlink_read_pend = 1;
	while (!skb && !(skb = skb_dequeue(&devlink->devlink_sio.rx_list))) {
		if (!wait_for_completion_interruptible_timeout
				(&devlink->devlink_sio.read_sem,
				 msecs_to_jiffies(IPC_READ_TIMEOUT))) {
			dev_err(devlink->dev, "Read timedout");
			rc =  -ETIMEDOUT;
			goto devlink_read_fail;
		}
	}
	devlink->devlink_sio.devlink_read_pend = 0;
	if (bytes_to_read < skb->len) {
		dev_err(devlink->dev, "Invalid size,expected len %d", skb->len);
		rc = -EINVAL;
		goto devlink_read_fail;
	}
	*bytes_read = skb->len;
	memcpy(data, skb->data, skb->len);

devlink_read_fail:
	dev_kfree_skb(skb);
	return rc;
}