drivers/staging/wfx/bh.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Interrupt bottom half (BH).
  *
  * Copyright (c) 2017-2019, Silicon Laboratories, Inc.
  * Copyright (c) 2010, ST-Ericsson
  */
 #include <linux/gpio/consumer.h>
 #include <net/mac80211.h>

 #include "bh.h"
 #include "wfx.h"
 #include "hwio.h"
 #include "traces.h"
 #include "secure_link.h"
 #include "hif_rx.h"
 #include "hif_api_cmd.h"

 static void device_wakeup(struct wfx_dev *wdev)
 {
 	if (!wdev->pdata.gpio_wakeup)
 		return;
 	if (gpiod_get_value_cansleep(wdev->pdata.gpio_wakeup))
 		return;

 	gpiod_set_value_cansleep(wdev->pdata.gpio_wakeup, 1);
 	if (wfx_api_older_than(wdev, 1, 4)) {
 		if (!completion_done(&wdev->hif.ctrl_ready))
 			usleep_range(2000, 2500);
 	} else {
 		// completion.h does not provide any function to wait
 		// completion without consume it (a kind of
 		// wait_for_completion_done_timeout()). So we have to emulate
 		// it.
 		if (wait_for_completion_timeout(&wdev->hif.ctrl_ready,
 						msecs_to_jiffies(2) + 1))
 			complete(&wdev->hif.ctrl_ready);
 		else
 			dev_err(wdev->dev, "timeout while wake up chip\n");
 	}
 }

 static void device_release(struct wfx_dev *wdev)
 {
 	if (!wdev->pdata.gpio_wakeup)
 		return;

 	gpiod_set_value_cansleep(wdev->pdata.gpio_wakeup, 0);
 }

 static int rx_helper(struct wfx_dev *wdev, size_t read_len, int *is_cnf)
 {
 	struct sk_buff *skb;
 	struct hif_msg *hif;
 	size_t alloc_len;
 	size_t computed_len;
 	int release_count;
 	int piggyback = 0;

 	WARN(read_len > round_down(0xFFF, 2) * sizeof(u16),
 	     "%s: request exceed WFx capability", __func__);

 	// Add 2 to take into account piggyback size
 	alloc_len = wdev->hwbus_ops->align_size(wdev->hwbus_priv, read_len + 2);
 	skb = dev_alloc_skb(alloc_len);
 	if (!skb)
 		return -ENOMEM;

 	if (wfx_data_read(wdev, skb->data, alloc_len))
 		goto err;

 	piggyback = le16_to_cpup((__le16 *)(skb->data + alloc_len - 2));
 	_trace_piggyback(piggyback, false);

 	hif = (struct hif_msg *)skb->data;
 	WARN(hif->encrypted & 0x1, "unsupported encryption type");
 	if (hif->encrypted == 0x2) {
 		if (WARN(read_len < sizeof(struct hif_sl_msg), "corrupted read"))
 			goto err;
 		computed_len = le16_to_cpu(((struct hif_sl_msg *)hif)->len);
 		computed_len = round_up(computed_len - sizeof(u16), 16);
 		computed_len += sizeof(struct hif_sl_msg);
 		computed_len += sizeof(struct hif_sl_tag);
 	} else {
 		if (WARN(read_len < sizeof(struct hif_msg), "corrupted read"))
 			goto err;
 		computed_len = le16_to_cpu(hif->len);
 		computed_len = round_up(computed_len, 2);
 	}
 	if (computed_len != read_len) {
 		dev_err(wdev->dev, "inconsistent message length: %zu != %zu\n",
 			computed_len, read_len);
 		print_hex_dump(KERN_INFO, "hif: ", DUMP_PREFIX_OFFSET, 16, 1,
 			       hif, read_len, true);
 		goto err;
 	}
 	if (hif->encrypted == 0x2) {
 		if (wfx_sl_decode(wdev, (struct hif_sl_msg *)hif)) {
 			dev_kfree_skb(skb);
 			// If frame was a confirmation, expect trouble in next
 			// exchange. However, it is harmless to fail to decode
 			// an indication frame, so try to continue. Anyway,
 			// piggyback is probably correct.
 			return piggyback;
 		}
 	}

 	if (!(hif->id & HIF_ID_IS_INDICATION)) {
 		(*is_cnf)++;
 		if (hif->id == HIF_CNF_ID_MULTI_TRANSMIT)
 			release_count = ((struct hif_cnf_multi_transmit *)hif->body)->num_tx_confs;
 		else
 			release_count = 1;
 		WARN(wdev->hif.tx_buffers_used < release_count, "corrupted buffer counter");
 		wdev->hif.tx_buffers_used -= release_count;
 	}
 	_trace_hif_recv(hif, wdev->hif.tx_buffers_used);

 	if (hif->id != HIF_IND_ID_EXCEPTION && hif->id != HIF_IND_ID_ERROR) {
 		if (hif->seqnum != wdev->hif.rx_seqnum)
 			dev_warn(wdev->dev, "wrong message sequence: %d != %d\n",
 				 hif->seqnum, wdev->hif.rx_seqnum);
 		wdev->hif.rx_seqnum = (hif->seqnum + 1) % (HIF_COUNTER_MAX + 1);
 	}

 	skb_put(skb, le16_to_cpu(hif->len));
 	// wfx_handle_rx takes care on SKB livetime
 	wfx_handle_rx(wdev, skb);
 	if (!wdev->hif.tx_buffers_used)
 		wake_up(&wdev->hif.tx_buffers_empty);

 	return piggyback;

 err:
 	if (skb)
 		dev_kfree_skb(skb);
 	return -EIO;
 }

 static int bh_work_rx(struct wfx_dev *wdev, int max_msg, int *num_cnf)
 {
 	size_t len;
 	int i;
 	int ctrl_reg, piggyback;

 	piggyback = 0;
 	for (i = 0; i < max_msg; i++) {
 		if (piggyback & CTRL_NEXT_LEN_MASK)
 			ctrl_reg = piggyback;
 		else if (try_wait_for_completion(&wdev->hif.ctrl_ready))
 			ctrl_reg = atomic_xchg(&wdev->hif.ctrl_reg, 0);
 		else
 			ctrl_reg = 0;
 		if (!(ctrl_reg & CTRL_NEXT_LEN_MASK))
 			return i;
 		// ctrl_reg units are 16bits words
 		len = (ctrl_reg & CTRL_NEXT_LEN_MASK) * 2;
 		piggyback = rx_helper(wdev, len, num_cnf);
 		if (piggyback < 0)
 			return i;
 		if (!(piggyback & CTRL_WLAN_READY))
 			dev_err(wdev->dev, "unexpected piggyback value: ready bit not set: %04x\n",
 				piggyback);
 	}
 	if (piggyback & CTRL_NEXT_LEN_MASK) {
 		ctrl_reg = atomic_xchg(&wdev->hif.ctrl_reg, piggyback);
 		complete(&wdev->hif.ctrl_ready);
 		if (ctrl_reg)
 			dev_err(wdev->dev, "unexpected IRQ happened: %04x/%04x\n",
 				ctrl_reg, piggyback);
 	}
 	return i;
 }

 static void tx_helper(struct wfx_dev *wdev, struct hif_msg *hif)
 {
 	int ret;
 	void *data;
 	bool is_encrypted = false;
 	size_t len = le16_to_cpu(hif->len);

 	WARN(len < sizeof(*hif), "try to send corrupted data");

 	hif->seqnum = wdev->hif.tx_seqnum;
 	wdev->hif.tx_seqnum = (wdev->hif.tx_seqnum + 1) % (HIF_COUNTER_MAX + 1);

 	if (wfx_is_secure_command(wdev, hif->id)) {
 		len = round_up(len - sizeof(hif->len), 16) + sizeof(hif->len) +
 			sizeof(struct hif_sl_msg_hdr) +
 			sizeof(struct hif_sl_tag);
 		// AES support encryption in-place. However, mac80211 access to
 		// 802.11 header after frame was sent (to get MAC addresses).
 		// So, keep origin buffer clear.
 		data = kmalloc(len, GFP_KERNEL);
 		if (!data)
 			goto end;
 		is_encrypted = true;
 		ret = wfx_sl_encode(wdev, hif, data);
 		if (ret)
 			goto end;
 	} else {
 		data = hif;
 	}
 	WARN(len > wdev->hw_caps.size_inp_ch_buf,
 	     "%s: request exceed WFx capability: %zu > %d\n", __func__,
 	     len, wdev->hw_caps.size_inp_ch_buf);
 	len = wdev->hwbus_ops->align_size(wdev->hwbus_priv, len);
 	ret = wfx_data_write(wdev, data, len);
 	if (ret)
 		goto end;

 	wdev->hif.tx_buffers_used++;
 	_trace_hif_send(hif, wdev->hif.tx_buffers_used);
 end:
 	if (is_encrypted)
 		kfree(data);
 }

 static int bh_work_tx(struct wfx_dev *wdev, int max_msg)
 {
 	struct hif_msg *hif;
 	int i;

 	for (i = 0; i < max_msg; i++) {
 		hif = NULL;
 		if (wdev->hif.tx_buffers_used < wdev->hw_caps.num_inp_ch_bufs) {
 			if (try_wait_for_completion(&wdev->hif_cmd.ready)) {
 				WARN(!mutex_is_locked(&wdev->hif_cmd.lock), "data locking error");
 				hif = wdev->hif_cmd.buf_send;
 			} else {
 				hif = wfx_tx_queues_get(wdev);
 			}
 		}
 		if (!hif)
 			return i;
 		tx_helper(wdev, hif);
 	}
 	return i;
 }

 /* In SDIO mode, it is necessary to make an access to a register to acknowledge
  * last received message. It could be possible to restrict this acknowledge to
  * SDIO mode and only if last operation was rx.
  */
 static void ack_sdio_data(struct wfx_dev *wdev)
 {
 	u32 cfg_reg;

 	config_reg_read(wdev, &cfg_reg);
 	if (cfg_reg & 0xFF) {
 		dev_warn(wdev->dev, "chip reports errors: %02x\n",
 			 cfg_reg & 0xFF);
 		config_reg_write_bits(wdev, 0xFF, 0x00);
 	}
 }

 static void bh_work(struct work_struct *work)
 {
 	struct wfx_dev *wdev = container_of(work, struct wfx_dev, hif.bh);
 	int stats_req = 0, stats_cnf = 0, stats_ind = 0;
 	bool release_chip = false, last_op_is_rx = false;
 	int num_tx, num_rx;

 	device_wakeup(wdev);
 	do {
 		num_tx = bh_work_tx(wdev, 32);
 		stats_req += num_tx;
 		if (num_tx)
 			last_op_is_rx = false;
 		num_rx = bh_work_rx(wdev, 32, &stats_cnf);
 		stats_ind += num_rx;
 		if (num_rx)
 			last_op_is_rx = true;
 	} while (num_rx || num_tx);
 	stats_ind -= stats_cnf;

 	if (last_op_is_rx)
 		ack_sdio_data(wdev);
 	if (!wdev->hif.tx_buffers_used && !work_pending(work)) {
 		device_release(wdev);
 		release_chip = true;
 	}
 	_trace_bh_stats(stats_ind, stats_req, stats_cnf,
 			wdev->hif.tx_buffers_used, release_chip);
 }

 /*
  * An IRQ from chip did occur
  */
 void wfx_bh_request_rx(struct wfx_dev *wdev)
 {
 	u32 cur, prev;

 	control_reg_read(wdev, &cur);
 	prev = atomic_xchg(&wdev->hif.ctrl_reg, cur);
 	complete(&wdev->hif.ctrl_ready);
 	queue_work(system_highpri_wq, &wdev->hif.bh);

 	if (!(cur & CTRL_NEXT_LEN_MASK))
 		dev_err(wdev->dev, "unexpected control register value: length field is 0: %04x\n",
 			cur);
 	if (prev != 0)
 		dev_err(wdev->dev, "received IRQ but previous data was not (yet) read: %04x/%04x\n",
 			prev, cur);
 }

 /*
  * Driver want to send data
  */
 void wfx_bh_request_tx(struct wfx_dev *wdev)
 {
 	queue_work(system_highpri_wq, &wdev->hif.bh);
 }

 /*
  * If IRQ is not available, this function allow to manually poll the control
  * register and simulate an IRQ ahen an event happened.
  *
  * Note that the device has a bug: If an IRQ raise while host read control
  * register, the IRQ is lost. So, use this function carefully (only duing
  * device initialisation).
  */
 void wfx_bh_poll_irq(struct wfx_dev *wdev)
 {
 	ktime_t now, start;
 	u32 reg;

 	WARN(!wdev->poll_irq, "unexpected IRQ polling can mask IRQ");
 	start = ktime_get();
 	for (;;) {
 		control_reg_read(wdev, &reg);
 		now = ktime_get();
 		if (reg & 0xFFF)
 			break;
 		if (ktime_after(now, ktime_add_ms(start, 1000))) {
 			dev_err(wdev->dev, "time out while polling control register\n");
 			return;
 		}
 		udelay(200);
 	}
 	wfx_bh_request_rx(wdev);
 }

 void wfx_bh_register(struct wfx_dev *wdev)
 {
 	INIT_WORK(&wdev->hif.bh, bh_work);
 	init_completion(&wdev->hif.ctrl_ready);
 	init_waitqueue_head(&wdev->hif.tx_buffers_empty);
 }

 void wfx_bh_unregister(struct wfx_dev *wdev)
 {
 	flush_work(&wdev->hif.bh);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Interrupt bottom half (BH).
	*
	* Copyright (c) 2017-2019, Silicon Laboratories, Inc.
	* Copyright (c) 2010, ST-Ericsson
	*/
	#include <linux/gpio/consumer.h>
	#include <net/mac80211.h>

	#include "bh.h"
	#include "wfx.h"
	#include "hwio.h"
	#include "traces.h"
	#include "secure_link.h"
	#include "hif_rx.h"
	#include "hif_api_cmd.h"

	static void device_wakeup(struct wfx_dev *wdev)
	{
	if (!wdev->pdata.gpio_wakeup)
	return;
	if (gpiod_get_value_cansleep(wdev->pdata.gpio_wakeup))
	return;

	gpiod_set_value_cansleep(wdev->pdata.gpio_wakeup, 1);
	if (wfx_api_older_than(wdev, 1, 4)) {
	if (!completion_done(&wdev->hif.ctrl_ready))
	usleep_range(2000, 2500);
	} else {
	// completion.h does not provide any function to wait
	// completion without consume it (a kind of
	// wait_for_completion_done_timeout()). So we have to emulate
	// it.
	if (wait_for_completion_timeout(&wdev->hif.ctrl_ready,
	msecs_to_jiffies(2) + 1))
	complete(&wdev->hif.ctrl_ready);
	else
	dev_err(wdev->dev, "timeout while wake up chip\n");
	}
	}

	static void device_release(struct wfx_dev *wdev)
	{
	if (!wdev->pdata.gpio_wakeup)
	return;

	gpiod_set_value_cansleep(wdev->pdata.gpio_wakeup, 0);
	}

	static int rx_helper(struct wfx_dev wdev, size_t read_len, int is_cnf)
	{
	struct sk_buff *skb;
	struct hif_msg *hif;
	size_t alloc_len;
	size_t computed_len;
	int release_count;
	int piggyback = 0;

	WARN(read_len > round_down(0xFFF, 2) * sizeof(u16),
	"%s: request exceed WFx capability", __func__);

	// Add 2 to take into account piggyback size
	alloc_len = wdev->hwbus_ops->align_size(wdev->hwbus_priv, read_len + 2);
	skb = dev_alloc_skb(alloc_len);
	if (!skb)
	return -ENOMEM;

	if (wfx_data_read(wdev, skb->data, alloc_len))
	goto err;

	piggyback = le16_to_cpup((__le16 *)(skb->data + alloc_len - 2));
	_trace_piggyback(piggyback, false);

	hif = (struct hif_msg *)skb->data;
	WARN(hif->encrypted & 0x1, "unsupported encryption type");
	if (hif->encrypted == 0x2) {
	if (WARN(read_len < sizeof(struct hif_sl_msg), "corrupted read"))
	goto err;
	computed_len = le16_to_cpu(((struct hif_sl_msg *)hif)->len);
	computed_len = round_up(computed_len - sizeof(u16), 16);
	computed_len += sizeof(struct hif_sl_msg);
	computed_len += sizeof(struct hif_sl_tag);
	} else {
	if (WARN(read_len < sizeof(struct hif_msg), "corrupted read"))
	goto err;
	computed_len = le16_to_cpu(hif->len);
	computed_len = round_up(computed_len, 2);
	}
	if (computed_len != read_len) {
	dev_err(wdev->dev, "inconsistent message length: %zu != %zu\n",
	computed_len, read_len);
	print_hex_dump(KERN_INFO, "hif: ", DUMP_PREFIX_OFFSET, 16, 1,
	hif, read_len, true);
	goto err;
	}
	if (hif->encrypted == 0x2) {
	if (wfx_sl_decode(wdev, (struct hif_sl_msg *)hif)) {
	dev_kfree_skb(skb);
	// If frame was a confirmation, expect trouble in next
	// exchange. However, it is harmless to fail to decode
	// an indication frame, so try to continue. Anyway,
	// piggyback is probably correct.
	return piggyback;
	}
	}

	if (!(hif->id & HIF_ID_IS_INDICATION)) {
	(*is_cnf)++;
	if (hif->id == HIF_CNF_ID_MULTI_TRANSMIT)
	release_count = ((struct hif_cnf_multi_transmit *)hif->body)->num_tx_confs;
	else
	release_count = 1;
	WARN(wdev->hif.tx_buffers_used < release_count, "corrupted buffer counter");
	wdev->hif.tx_buffers_used -= release_count;
	}
	_trace_hif_recv(hif, wdev->hif.tx_buffers_used);

	if (hif->id != HIF_IND_ID_EXCEPTION && hif->id != HIF_IND_ID_ERROR) {
	if (hif->seqnum != wdev->hif.rx_seqnum)
	dev_warn(wdev->dev, "wrong message sequence: %d != %d\n",
	hif->seqnum, wdev->hif.rx_seqnum);
	wdev->hif.rx_seqnum = (hif->seqnum + 1) % (HIF_COUNTER_MAX + 1);
	}

	skb_put(skb, le16_to_cpu(hif->len));
	// wfx_handle_rx takes care on SKB livetime
	wfx_handle_rx(wdev, skb);
	if (!wdev->hif.tx_buffers_used)
	wake_up(&wdev->hif.tx_buffers_empty);

	return piggyback;

	err:
	if (skb)
	dev_kfree_skb(skb);
	return -EIO;
	}

	static int bh_work_rx(struct wfx_dev wdev, int max_msg, int num_cnf)
	{
	size_t len;
	int i;
	int ctrl_reg, piggyback;

	piggyback = 0;
	for (i = 0; i < max_msg; i++) {
	if (piggyback & CTRL_NEXT_LEN_MASK)
	ctrl_reg = piggyback;
	else if (try_wait_for_completion(&wdev->hif.ctrl_ready))
	ctrl_reg = atomic_xchg(&wdev->hif.ctrl_reg, 0);
	else
	ctrl_reg = 0;
	if (!(ctrl_reg & CTRL_NEXT_LEN_MASK))
	return i;
	// ctrl_reg units are 16bits words
	len = (ctrl_reg & CTRL_NEXT_LEN_MASK) * 2;
	piggyback = rx_helper(wdev, len, num_cnf);
	if (piggyback < 0)
	return i;
	if (!(piggyback & CTRL_WLAN_READY))
	dev_err(wdev->dev, "unexpected piggyback value: ready bit not set: %04x\n",
	piggyback);
	}
	if (piggyback & CTRL_NEXT_LEN_MASK) {
	ctrl_reg = atomic_xchg(&wdev->hif.ctrl_reg, piggyback);
	complete(&wdev->hif.ctrl_ready);
	if (ctrl_reg)
	dev_err(wdev->dev, "unexpected IRQ happened: %04x/%04x\n",
	ctrl_reg, piggyback);
	}
	return i;
	}

	static void tx_helper(struct wfx_dev wdev, struct hif_msg hif)
	{
	int ret;
	void *data;
	bool is_encrypted = false;
	size_t len = le16_to_cpu(hif->len);

	WARN(len < sizeof(*hif), "try to send corrupted data");

	hif->seqnum = wdev->hif.tx_seqnum;
	wdev->hif.tx_seqnum = (wdev->hif.tx_seqnum + 1) % (HIF_COUNTER_MAX + 1);

	if (wfx_is_secure_command(wdev, hif->id)) {
	len = round_up(len - sizeof(hif->len), 16) + sizeof(hif->len) +
	sizeof(struct hif_sl_msg_hdr) +
	sizeof(struct hif_sl_tag);
	// AES support encryption in-place. However, mac80211 access to
	// 802.11 header after frame was sent (to get MAC addresses).
	// So, keep origin buffer clear.
	data = kmalloc(len, GFP_KERNEL);
	if (!data)
	goto end;
	is_encrypted = true;
	ret = wfx_sl_encode(wdev, hif, data);
	if (ret)
	goto end;
	} else {
	data = hif;
	}
	WARN(len > wdev->hw_caps.size_inp_ch_buf,
	"%s: request exceed WFx capability: %zu > %d\n", __func__,
	len, wdev->hw_caps.size_inp_ch_buf);
	len = wdev->hwbus_ops->align_size(wdev->hwbus_priv, len);
	ret = wfx_data_write(wdev, data, len);
	if (ret)
	goto end;

	wdev->hif.tx_buffers_used++;
	_trace_hif_send(hif, wdev->hif.tx_buffers_used);
	end:
	if (is_encrypted)
	kfree(data);
	}

	static int bh_work_tx(struct wfx_dev *wdev, int max_msg)
	{
	struct hif_msg *hif;
	int i;

	for (i = 0; i < max_msg; i++) {
	hif = NULL;
	if (wdev->hif.tx_buffers_used < wdev->hw_caps.num_inp_ch_bufs) {
	if (try_wait_for_completion(&wdev->hif_cmd.ready)) {
	WARN(!mutex_is_locked(&wdev->hif_cmd.lock), "data locking error");
	hif = wdev->hif_cmd.buf_send;
	} else {
	hif = wfx_tx_queues_get(wdev);
	}
	}
	if (!hif)
	return i;
	tx_helper(wdev, hif);
	}
	return i;
	}

	/* In SDIO mode, it is necessary to make an access to a register to acknowledge
	* last received message. It could be possible to restrict this acknowledge to
	* SDIO mode and only if last operation was rx.
	*/
	static void ack_sdio_data(struct wfx_dev *wdev)
	{
	u32 cfg_reg;

	config_reg_read(wdev, &cfg_reg);
	if (cfg_reg & 0xFF) {
	dev_warn(wdev->dev, "chip reports errors: %02x\n",
	cfg_reg & 0xFF);
	config_reg_write_bits(wdev, 0xFF, 0x00);
	}
	}

	static void bh_work(struct work_struct *work)
	{
	struct wfx_dev *wdev = container_of(work, struct wfx_dev, hif.bh);
	int stats_req = 0, stats_cnf = 0, stats_ind = 0;
	bool release_chip = false, last_op_is_rx = false;
	int num_tx, num_rx;

	device_wakeup(wdev);
	do {
	num_tx = bh_work_tx(wdev, 32);
	stats_req += num_tx;
	if (num_tx)
	last_op_is_rx = false;
	num_rx = bh_work_rx(wdev, 32, &stats_cnf);
	stats_ind += num_rx;
	if (num_rx)
	last_op_is_rx = true;
	} while (num_rx \|\| num_tx);
	stats_ind -= stats_cnf;

	if (last_op_is_rx)
	ack_sdio_data(wdev);
	if (!wdev->hif.tx_buffers_used && !work_pending(work)) {
	device_release(wdev);
	release_chip = true;
	}
	_trace_bh_stats(stats_ind, stats_req, stats_cnf,
	wdev->hif.tx_buffers_used, release_chip);
	}

	/*
	* An IRQ from chip did occur
	*/
	void wfx_bh_request_rx(struct wfx_dev *wdev)
	{
	u32 cur, prev;

	control_reg_read(wdev, &cur);
	prev = atomic_xchg(&wdev->hif.ctrl_reg, cur);
	complete(&wdev->hif.ctrl_ready);
	queue_work(system_highpri_wq, &wdev->hif.bh);

	if (!(cur & CTRL_NEXT_LEN_MASK))
	dev_err(wdev->dev, "unexpected control register value: length field is 0: %04x\n",
	cur);
	if (prev != 0)
	dev_err(wdev->dev, "received IRQ but previous data was not (yet) read: %04x/%04x\n",
	prev, cur);
	}

	/*
	* Driver want to send data
	*/
	void wfx_bh_request_tx(struct wfx_dev *wdev)
	{
	queue_work(system_highpri_wq, &wdev->hif.bh);
	}

	/*
	* If IRQ is not available, this function allow to manually poll the control
	* register and simulate an IRQ ahen an event happened.
	*
	* Note that the device has a bug: If an IRQ raise while host read control
	* register, the IRQ is lost. So, use this function carefully (only duing
	* device initialisation).
	*/
	void wfx_bh_poll_irq(struct wfx_dev *wdev)
	{
	ktime_t now, start;
	u32 reg;

	WARN(!wdev->poll_irq, "unexpected IRQ polling can mask IRQ");
	start = ktime_get();
	for (;;) {
	control_reg_read(wdev, &reg);
	now = ktime_get();
	if (reg & 0xFFF)
	break;
	if (ktime_after(now, ktime_add_ms(start, 1000))) {
	dev_err(wdev->dev, "time out while polling control register\n");
	return;
	}
	udelay(200);
	}
	wfx_bh_request_rx(wdev);
	}

	void wfx_bh_register(struct wfx_dev *wdev)
	{
	INIT_WORK(&wdev->hif.bh, bh_work);
	init_completion(&wdev->hif.ctrl_ready);
	init_waitqueue_head(&wdev->hif.tx_buffers_empty);
	}

	void wfx_bh_unregister(struct wfx_dev *wdev)
	{
	flush_work(&wdev->hif.bh);
	}