drivers/media/pci/tw686x/tw686x-core.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2015 VanguardiaSur - www.vanguardiasur.com.ar
  *
  * Based on original driver by Krzysztof Ha?asa:
  * Copyright (C) 2015 Industrial Research Institute for Automation
  * and Measurements PIAP
  *
  * Notes
  * -----
  *
  * 1. Under stress-testing, it has been observed that the PCIe link
  * goes down, without reason. Therefore, the driver takes special care
  * to allow device hot-unplugging.
  *
  * 2. TW686X devices are capable of setting a few different DMA modes,
  * including: scatter-gather, field and frame modes. However,
  * under stress testings it has been found that the machine can
  * freeze completely if DMA registers are programmed while streaming
  * is active.
  *
  * Therefore, driver implements a dma_mode called 'memcpy' which
  * avoids cycling the DMA buffers, and insteads allocates extra DMA buffers
  * and then copies into vmalloc'ed user buffers.
  *
  * In addition to this, when streaming is on, the driver tries to access
  * hardware registers as infrequently as possible. This is done by using
  * a timer to limit the rate at which DMA is reset on DMA channels error.
  */

 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci_ids.h>
 #include <linux/slab.h>
 #include <linux/timer.h>

 #include "tw686x.h"
 #include "tw686x-regs.h"

 /*
  * This module parameter allows to control the DMA_TIMER_INTERVAL value.
  * The DMA_TIMER_INTERVAL register controls the minimum DMA interrupt
  * time span (iow, the maximum DMA interrupt rate) thus allowing for
  * IRQ coalescing.
  *
  * The chip datasheet does not mention a time unit for this value, so
  * users wanting fine-grain control over the interrupt rate should
  * determine the desired value through testing.
  */
 static u32 dma_interval = 0x00098968;
 module_param(dma_interval, int, 0444);
 MODULE_PARM_DESC(dma_interval, "Minimum time span for DMA interrupting host");

 static unsigned int dma_mode = TW686X_DMA_MODE_MEMCPY;
 static const char *dma_mode_name(unsigned int mode)
 {
 	switch (mode) {
 	case TW686X_DMA_MODE_MEMCPY:
 		return "memcpy";
 	case TW686X_DMA_MODE_CONTIG:
 		return "contig";
 	case TW686X_DMA_MODE_SG:
 		return "sg";
 	default:
 		return "unknown";
 	}
 }

 static int tw686x_dma_mode_get(char *buffer, const struct kernel_param *kp)
 {
 	return sprintf(buffer, "%s", dma_mode_name(dma_mode));
 }

 static int tw686x_dma_mode_set(const char *val, const struct kernel_param *kp)
 {
 	if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_MEMCPY)))
 		dma_mode = TW686X_DMA_MODE_MEMCPY;
 	else if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_CONTIG)))
 		dma_mode = TW686X_DMA_MODE_CONTIG;
 	else if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_SG)))
 		dma_mode = TW686X_DMA_MODE_SG;
 	else
 		return -EINVAL;
 	return 0;
 }
 module_param_call(dma_mode, tw686x_dma_mode_set, tw686x_dma_mode_get,
 		  &dma_mode, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(dma_mode, "DMA operation mode (memcpy/contig/sg, default=memcpy)");

 void tw686x_disable_channel(struct tw686x_dev *dev, unsigned int channel)
 {
 	u32 dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
 	u32 dma_cmd = reg_read(dev, DMA_CMD);

 	dma_en &= ~BIT(channel);
 	dma_cmd &= ~BIT(channel);

 	/* Must remove it from pending too */
 	dev->pending_dma_en &= ~BIT(channel);
 	dev->pending_dma_cmd &= ~BIT(channel);

 	/* Stop DMA if no channels are enabled */
 	if (!dma_en)
 		dma_cmd = 0;
 	reg_write(dev, DMA_CHANNEL_ENABLE, dma_en);
 	reg_write(dev, DMA_CMD, dma_cmd);
 }

 void tw686x_enable_channel(struct tw686x_dev *dev, unsigned int channel)
 {
 	u32 dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
 	u32 dma_cmd = reg_read(dev, DMA_CMD);

 	dev->pending_dma_en |= dma_en | BIT(channel);
 	dev->pending_dma_cmd |= dma_cmd | DMA_CMD_ENABLE | BIT(channel);
 }

 /*
  * The purpose of this awful hack is to avoid enabling the DMA
  * channels "too fast" which makes some TW686x devices very
  * angry and freeze the CPU (see note 1).
  */
 static void tw686x_dma_delay(struct timer_list *t)
 {
 	struct tw686x_dev *dev = from_timer(dev, t, dma_delay_timer);
 	unsigned long flags;

 	spin_lock_irqsave(&dev->lock, flags);

 	reg_write(dev, DMA_CHANNEL_ENABLE, dev->pending_dma_en);
 	reg_write(dev, DMA_CMD, dev->pending_dma_cmd);
 	dev->pending_dma_en = 0;
 	dev->pending_dma_cmd = 0;

 	spin_unlock_irqrestore(&dev->lock, flags);
 }

 static void tw686x_reset_channels(struct tw686x_dev *dev, unsigned int ch_mask)
 {
 	u32 dma_en, dma_cmd;

 	dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
 	dma_cmd = reg_read(dev, DMA_CMD);

 	/*
 	 * Save pending register status, the timer will
 	 * restore them.
 	 */
 	dev->pending_dma_en |= dma_en;
 	dev->pending_dma_cmd |= dma_cmd;

 	/* Disable the reset channels */
 	reg_write(dev, DMA_CHANNEL_ENABLE, dma_en & ~ch_mask);

 	if ((dma_en & ~ch_mask) == 0) {
 		dev_dbg(&dev->pci_dev->dev, "reset: stopping DMA\n");
 		dma_cmd &= ~DMA_CMD_ENABLE;
 	}
 	reg_write(dev, DMA_CMD, dma_cmd & ~ch_mask);
 }

 static irqreturn_t tw686x_irq(int irq, void *dev_id)
 {
 	struct tw686x_dev *dev = (struct tw686x_dev *)dev_id;
 	unsigned int video_requests, audio_requests, reset_ch;
 	u32 fifo_status, fifo_signal, fifo_ov, fifo_bad, fifo_errors;
 	u32 int_status, dma_en, video_en, pb_status;
 	unsigned long flags;

 	int_status = reg_read(dev, INT_STATUS); /* cleared on read */
 	fifo_status = reg_read(dev, VIDEO_FIFO_STATUS);

 	/* INT_STATUS does not include FIFO_STATUS errors! */
 	if (!int_status && !TW686X_FIFO_ERROR(fifo_status))
 		return IRQ_NONE;

 	if (int_status & INT_STATUS_DMA_TOUT) {
 		dev_dbg(&dev->pci_dev->dev,
 			"DMA timeout. Resetting DMA for all channels\n");
 		reset_ch = ~0;
 		goto reset_channels;
 	}

 	spin_lock_irqsave(&dev->lock, flags);
 	dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
 	spin_unlock_irqrestore(&dev->lock, flags);

 	video_en = dma_en & 0xff;
 	fifo_signal = ~(fifo_status & 0xff) & video_en;
 	fifo_ov = fifo_status >> 24;
 	fifo_bad = fifo_status >> 16;

 	/* Mask of channels with signal and FIFO errors */
 	fifo_errors = fifo_signal & (fifo_ov | fifo_bad);

 	reset_ch = 0;
 	pb_status = reg_read(dev, PB_STATUS);

 	/* Coalesce video frame/error events */
 	video_requests = (int_status & video_en) | fifo_errors;
 	audio_requests = (int_status & dma_en) >> 8;

 	if (video_requests)
 		tw686x_video_irq(dev, video_requests, pb_status,
 				 fifo_status, &reset_ch);
 	if (audio_requests)
 		tw686x_audio_irq(dev, audio_requests, pb_status);

 reset_channels:
 	if (reset_ch) {
 		spin_lock_irqsave(&dev->lock, flags);
 		tw686x_reset_channels(dev, reset_ch);
 		spin_unlock_irqrestore(&dev->lock, flags);
 		mod_timer(&dev->dma_delay_timer,
 			  jiffies + msecs_to_jiffies(100));
 	}

 	return IRQ_HANDLED;
 }

 static void tw686x_dev_release(struct v4l2_device *v4l2_dev)
 {
 	struct tw686x_dev *dev = container_of(v4l2_dev, struct tw686x_dev,
 					      v4l2_dev);
 	unsigned int ch;

 	for (ch = 0; ch < max_channels(dev); ch++)
 		v4l2_ctrl_handler_free(&dev->video_channels[ch].ctrl_handler);

 	v4l2_device_unregister(&dev->v4l2_dev);

 	kfree(dev->audio_channels);
 	kfree(dev->video_channels);
 	kfree(dev);
 }

 static int tw686x_probe(struct pci_dev *pci_dev,
 			const struct pci_device_id *pci_id)
 {
 	struct tw686x_dev *dev;
 	int err;

 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 	if (!dev)
 		return -ENOMEM;
 	dev->type = pci_id->driver_data;
 	dev->dma_mode = dma_mode;
 	sprintf(dev->name, "tw%04X", pci_dev->device);

 	dev->video_channels = kcalloc(max_channels(dev),
 		sizeof(*dev->video_channels), GFP_KERNEL);
 	if (!dev->video_channels) {
 		err = -ENOMEM;
 		goto free_dev;
 	}

 	dev->audio_channels = kcalloc(max_channels(dev),
 		sizeof(*dev->audio_channels), GFP_KERNEL);
 	if (!dev->audio_channels) {
 		err = -ENOMEM;
 		goto free_video;
 	}

 	pr_info("%s: PCI %s, IRQ %d, MMIO 0x%lx (%s mode)\n", dev->name,
 		pci_name(pci_dev), pci_dev->irq,
 		(unsigned long)pci_resource_start(pci_dev, 0),
 		dma_mode_name(dma_mode));

 	dev->pci_dev = pci_dev;
 	if (pci_enable_device(pci_dev)) {
 		err = -EIO;
 		goto free_audio;
 	}

 	pci_set_master(pci_dev);
 	err = dma_set_mask(&pci_dev->dev, DMA_BIT_MASK(32));
 	if (err) {
 		dev_err(&pci_dev->dev, "32-bit PCI DMA not supported\n");
 		err = -EIO;
 		goto disable_pci;
 	}

 	err = pci_request_regions(pci_dev, dev->name);
 	if (err) {
 		dev_err(&pci_dev->dev, "unable to request PCI region\n");
 		goto disable_pci;
 	}

 	dev->mmio = pci_ioremap_bar(pci_dev, 0);
 	if (!dev->mmio) {
 		dev_err(&pci_dev->dev, "unable to remap PCI region\n");
 		err = -ENOMEM;
 		goto free_region;
 	}

 	/* Reset all subsystems */
 	reg_write(dev, SYS_SOFT_RST, 0x0f);
 	mdelay(1);

 	reg_write(dev, SRST[0], 0x3f);
 	if (max_channels(dev) > 4)
 		reg_write(dev, SRST[1], 0x3f);

 	/* Disable the DMA engine */
 	reg_write(dev, DMA_CMD, 0);
 	reg_write(dev, DMA_CHANNEL_ENABLE, 0);

 	/* Enable DMA FIFO overflow and pointer check */
 	reg_write(dev, DMA_CONFIG, 0xffffff04);
 	reg_write(dev, DMA_CHANNEL_TIMEOUT, 0x140c8584);
 	reg_write(dev, DMA_TIMER_INTERVAL, dma_interval);

 	spin_lock_init(&dev->lock);

 	timer_setup(&dev->dma_delay_timer, tw686x_dma_delay, 0);

 	/*
 	 * This must be set right before initializing v4l2_dev.
 	 * It's used to release resources after the last handle
 	 * held is released.
 	 */
 	dev->v4l2_dev.release = tw686x_dev_release;
 	err = tw686x_video_init(dev);
 	if (err) {
 		dev_err(&pci_dev->dev, "can't register video\n");
 		goto iounmap;
 	}

 	err = tw686x_audio_init(dev);
 	if (err)
 		dev_warn(&pci_dev->dev, "can't register audio\n");

 	err = request_irq(pci_dev->irq, tw686x_irq, IRQF_SHARED,
 			  dev->name, dev);
 	if (err < 0) {
 		dev_err(&pci_dev->dev, "unable to request interrupt\n");
 		goto tw686x_free;
 	}

 	pci_set_drvdata(pci_dev, dev);
 	return 0;

 tw686x_free:
 	tw686x_video_free(dev);
 	tw686x_audio_free(dev);
 iounmap:
 	pci_iounmap(pci_dev, dev->mmio);
 free_region:
 	pci_release_regions(pci_dev);
 disable_pci:
 	pci_disable_device(pci_dev);
 free_audio:
 	kfree(dev->audio_channels);
 free_video:
 	kfree(dev->video_channels);
 free_dev:
 	kfree(dev);
 	return err;
 }

 static void tw686x_remove(struct pci_dev *pci_dev)
 {
 	struct tw686x_dev *dev = pci_get_drvdata(pci_dev);
 	unsigned long flags;

 	/* This guarantees the IRQ handler is no longer running,
 	 * which means we can kiss good-bye some resources.
 	 */
 	free_irq(pci_dev->irq, dev);

 	tw686x_video_free(dev);
 	tw686x_audio_free(dev);
 	del_timer_sync(&dev->dma_delay_timer);

 	pci_iounmap(pci_dev, dev->mmio);
 	pci_release_regions(pci_dev);
 	pci_disable_device(pci_dev);

 	/*
 	 * Setting pci_dev to NULL allows to detect hardware is no longer
 	 * available and will be used by vb2_ops. This is required because
 	 * the device sometimes hot-unplugs itself as the result of a PCIe
 	 * link down.
 	 * The lock is really important here.
 	 */
 	spin_lock_irqsave(&dev->lock, flags);
 	dev->pci_dev = NULL;
 	spin_unlock_irqrestore(&dev->lock, flags);

 	/*
 	 * This calls tw686x_dev_release if it's the last reference.
 	 * Otherwise, release is postponed until there are no users left.
 	 */
 	v4l2_device_put(&dev->v4l2_dev);
 }

 /*
  * On TW6864 and TW6868, all channels share the pair of video DMA SG tables,
  * with 10-bit start_idx and end_idx determining start and end of frame buffer
  * for particular channel.
  * TW6868 with all its 8 channels would be problematic (only 127 SG entries per
  * channel) but we support only 4 channels on this chip anyway (the first
  * 4 channels are driven with internal video decoder, the other 4 would require
  * an external TW286x part).
  *
  * On TW6865 and TW6869, each channel has its own DMA SG table, with indexes
  * starting with 0. Both chips have complete sets of internal video decoders
  * (respectively 4 or 8-channel).
  *
  * All chips have separate SG tables for two video frames.
  */

 /* driver_data is number of A/V channels */
 static const struct pci_device_id tw686x_pci_tbl[] = {
 	{
 		PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6864),
 		.driver_data = 4
 	},
 	{
 		PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6865), /* not tested */
 		.driver_data = 4 | TYPE_SECOND_GEN
 	},
 	/*
 	 * TW6868 supports 8 A/V channels with an external TW2865 chip;
 	 * not supported by the driver.
 	 */
 	{
 		PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6868), /* not tested */
 		.driver_data = 4
 	},
 	{
 		PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6869),
 		.driver_data = 8 | TYPE_SECOND_GEN},
 	{}
 };
 MODULE_DEVICE_TABLE(pci, tw686x_pci_tbl);

 static struct pci_driver tw686x_pci_driver = {
 	.name = "tw686x",
 	.id_table = tw686x_pci_tbl,
 	.probe = tw686x_probe,
 	.remove = tw686x_remove,
 };
 module_pci_driver(tw686x_pci_driver);

 MODULE_DESCRIPTION("Driver for video frame grabber cards based on Intersil/Techwell TW686[4589]");
 MODULE_AUTHOR("Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>");
 MODULE_AUTHOR("Krzysztof Ha?asa <khalasa@piap.pl>");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (C) 2015 VanguardiaSur - www.vanguardiasur.com.ar
	*
	* Based on original driver by Krzysztof Ha?asa:
	* Copyright (C) 2015 Industrial Research Institute for Automation
	* and Measurements PIAP
	*
	* Notes
	* -----
	*
	* 1. Under stress-testing, it has been observed that the PCIe link
	* goes down, without reason. Therefore, the driver takes special care
	* to allow device hot-unplugging.
	*
	* 2. TW686X devices are capable of setting a few different DMA modes,
	* including: scatter-gather, field and frame modes. However,
	* under stress testings it has been found that the machine can
	* freeze completely if DMA registers are programmed while streaming
	* is active.
	*
	* Therefore, driver implements a dma_mode called 'memcpy' which
	* avoids cycling the DMA buffers, and insteads allocates extra DMA buffers
	* and then copies into vmalloc'ed user buffers.
	*
	* In addition to this, when streaming is on, the driver tries to access
	* hardware registers as infrequently as possible. This is done by using
	* a timer to limit the rate at which DMA is reset on DMA channels error.
	*/

	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/delay.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/pci_ids.h>
	#include <linux/slab.h>
	#include <linux/timer.h>

	#include "tw686x.h"
	#include "tw686x-regs.h"

	/*
	* This module parameter allows to control the DMA_TIMER_INTERVAL value.
	* The DMA_TIMER_INTERVAL register controls the minimum DMA interrupt
	* time span (iow, the maximum DMA interrupt rate) thus allowing for
	* IRQ coalescing.
	*
	* The chip datasheet does not mention a time unit for this value, so
	* users wanting fine-grain control over the interrupt rate should
	* determine the desired value through testing.
	*/
	static u32 dma_interval = 0x00098968;
	module_param(dma_interval, int, 0444);
	MODULE_PARM_DESC(dma_interval, "Minimum time span for DMA interrupting host");

	static unsigned int dma_mode = TW686X_DMA_MODE_MEMCPY;
	static const char *dma_mode_name(unsigned int mode)
	{
	switch (mode) {
	case TW686X_DMA_MODE_MEMCPY:
	return "memcpy";
	case TW686X_DMA_MODE_CONTIG:
	return "contig";
	case TW686X_DMA_MODE_SG:
	return "sg";
	default:
	return "unknown";
	}
	}

	static int tw686x_dma_mode_get(char buffer, const struct kernel_param kp)
	{
	return sprintf(buffer, "%s", dma_mode_name(dma_mode));
	}

	static int tw686x_dma_mode_set(const char val, const struct kernel_param kp)
	{
	if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_MEMCPY)))
	dma_mode = TW686X_DMA_MODE_MEMCPY;
	else if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_CONTIG)))
	dma_mode = TW686X_DMA_MODE_CONTIG;
	else if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_SG)))
	dma_mode = TW686X_DMA_MODE_SG;
	else
	return -EINVAL;
	return 0;
	}
	module_param_call(dma_mode, tw686x_dma_mode_set, tw686x_dma_mode_get,
	&dma_mode, S_IRUGO\|S_IWUSR);
	MODULE_PARM_DESC(dma_mode, "DMA operation mode (memcpy/contig/sg, default=memcpy)");

	void tw686x_disable_channel(struct tw686x_dev *dev, unsigned int channel)
	{
	u32 dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
	u32 dma_cmd = reg_read(dev, DMA_CMD);

	dma_en &= ~BIT(channel);
	dma_cmd &= ~BIT(channel);

	/* Must remove it from pending too */
	dev->pending_dma_en &= ~BIT(channel);
	dev->pending_dma_cmd &= ~BIT(channel);

	/* Stop DMA if no channels are enabled */
	if (!dma_en)
	dma_cmd = 0;
	reg_write(dev, DMA_CHANNEL_ENABLE, dma_en);
	reg_write(dev, DMA_CMD, dma_cmd);
	}

	void tw686x_enable_channel(struct tw686x_dev *dev, unsigned int channel)
	{
	u32 dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
	u32 dma_cmd = reg_read(dev, DMA_CMD);

	dev->pending_dma_en \|= dma_en \| BIT(channel);
	dev->pending_dma_cmd \|= dma_cmd \| DMA_CMD_ENABLE \| BIT(channel);
	}

	/*
	* The purpose of this awful hack is to avoid enabling the DMA
	* channels "too fast" which makes some TW686x devices very
	* angry and freeze the CPU (see note 1).
	*/
	static void tw686x_dma_delay(struct timer_list *t)
	{
	struct tw686x_dev *dev = from_timer(dev, t, dma_delay_timer);
	unsigned long flags;

	spin_lock_irqsave(&dev->lock, flags);

	reg_write(dev, DMA_CHANNEL_ENABLE, dev->pending_dma_en);
	reg_write(dev, DMA_CMD, dev->pending_dma_cmd);
	dev->pending_dma_en = 0;
	dev->pending_dma_cmd = 0;

	spin_unlock_irqrestore(&dev->lock, flags);
	}

	static void tw686x_reset_channels(struct tw686x_dev *dev, unsigned int ch_mask)
	{
	u32 dma_en, dma_cmd;

	dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
	dma_cmd = reg_read(dev, DMA_CMD);

	/*
	* Save pending register status, the timer will
	* restore them.
	*/
	dev->pending_dma_en \|= dma_en;
	dev->pending_dma_cmd \|= dma_cmd;

	/* Disable the reset channels */
	reg_write(dev, DMA_CHANNEL_ENABLE, dma_en & ~ch_mask);

	if ((dma_en & ~ch_mask) == 0) {
	dev_dbg(&dev->pci_dev->dev, "reset: stopping DMA\n");
	dma_cmd &= ~DMA_CMD_ENABLE;
	}
	reg_write(dev, DMA_CMD, dma_cmd & ~ch_mask);
	}

	static irqreturn_t tw686x_irq(int irq, void *dev_id)
	{
	struct tw686x_dev dev = (struct tw686x_dev )dev_id;
	unsigned int video_requests, audio_requests, reset_ch;
	u32 fifo_status, fifo_signal, fifo_ov, fifo_bad, fifo_errors;
	u32 int_status, dma_en, video_en, pb_status;
	unsigned long flags;

	int_status = reg_read(dev, INT_STATUS); /* cleared on read */
	fifo_status = reg_read(dev, VIDEO_FIFO_STATUS);

	/* INT_STATUS does not include FIFO_STATUS errors! */
	if (!int_status && !TW686X_FIFO_ERROR(fifo_status))
	return IRQ_NONE;

	if (int_status & INT_STATUS_DMA_TOUT) {
	dev_dbg(&dev->pci_dev->dev,
	"DMA timeout. Resetting DMA for all channels\n");
	reset_ch = ~0;
	goto reset_channels;
	}

	spin_lock_irqsave(&dev->lock, flags);
	dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
	spin_unlock_irqrestore(&dev->lock, flags);

	video_en = dma_en & 0xff;
	fifo_signal = ~(fifo_status & 0xff) & video_en;
	fifo_ov = fifo_status >> 24;
	fifo_bad = fifo_status >> 16;

	/* Mask of channels with signal and FIFO errors */
	fifo_errors = fifo_signal & (fifo_ov \| fifo_bad);

	reset_ch = 0;
	pb_status = reg_read(dev, PB_STATUS);

	/* Coalesce video frame/error events */
	video_requests = (int_status & video_en) \| fifo_errors;
	audio_requests = (int_status & dma_en) >> 8;

	if (video_requests)
	tw686x_video_irq(dev, video_requests, pb_status,
	fifo_status, &reset_ch);
	if (audio_requests)
	tw686x_audio_irq(dev, audio_requests, pb_status);

	reset_channels:
	if (reset_ch) {
	spin_lock_irqsave(&dev->lock, flags);
	tw686x_reset_channels(dev, reset_ch);
	spin_unlock_irqrestore(&dev->lock, flags);
	mod_timer(&dev->dma_delay_timer,
	jiffies + msecs_to_jiffies(100));
	}

	return IRQ_HANDLED;
	}

	static void tw686x_dev_release(struct v4l2_device *v4l2_dev)
	{
	struct tw686x_dev *dev = container_of(v4l2_dev, struct tw686x_dev,
	v4l2_dev);
	unsigned int ch;

	for (ch = 0; ch < max_channels(dev); ch++)
	v4l2_ctrl_handler_free(&dev->video_channels[ch].ctrl_handler);

	v4l2_device_unregister(&dev->v4l2_dev);

	kfree(dev->audio_channels);
	kfree(dev->video_channels);
	kfree(dev);
	}

	static int tw686x_probe(struct pci_dev *pci_dev,
	const struct pci_device_id *pci_id)
	{
	struct tw686x_dev *dev;
	int err;

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
	return -ENOMEM;
	dev->type = pci_id->driver_data;
	dev->dma_mode = dma_mode;
	sprintf(dev->name, "tw%04X", pci_dev->device);

	dev->video_channels = kcalloc(max_channels(dev),
	sizeof(*dev->video_channels), GFP_KERNEL);
	if (!dev->video_channels) {
	err = -ENOMEM;
	goto free_dev;
	}

	dev->audio_channels = kcalloc(max_channels(dev),
	sizeof(*dev->audio_channels), GFP_KERNEL);
	if (!dev->audio_channels) {
	err = -ENOMEM;
	goto free_video;
	}

	pr_info("%s: PCI %s, IRQ %d, MMIO 0x%lx (%s mode)\n", dev->name,
	pci_name(pci_dev), pci_dev->irq,
	(unsigned long)pci_resource_start(pci_dev, 0),
	dma_mode_name(dma_mode));

	dev->pci_dev = pci_dev;
	if (pci_enable_device(pci_dev)) {
	err = -EIO;
	goto free_audio;
	}

	pci_set_master(pci_dev);
	err = dma_set_mask(&pci_dev->dev, DMA_BIT_MASK(32));
	if (err) {
	dev_err(&pci_dev->dev, "32-bit PCI DMA not supported\n");
	err = -EIO;
	goto disable_pci;
	}

	err = pci_request_regions(pci_dev, dev->name);
	if (err) {
	dev_err(&pci_dev->dev, "unable to request PCI region\n");
	goto disable_pci;
	}

	dev->mmio = pci_ioremap_bar(pci_dev, 0);
	if (!dev->mmio) {
	dev_err(&pci_dev->dev, "unable to remap PCI region\n");
	err = -ENOMEM;
	goto free_region;
	}

	/* Reset all subsystems */
	reg_write(dev, SYS_SOFT_RST, 0x0f);
	mdelay(1);

	reg_write(dev, SRST[0], 0x3f);
	if (max_channels(dev) > 4)
	reg_write(dev, SRST[1], 0x3f);

	/* Disable the DMA engine */
	reg_write(dev, DMA_CMD, 0);
	reg_write(dev, DMA_CHANNEL_ENABLE, 0);

	/* Enable DMA FIFO overflow and pointer check */
	reg_write(dev, DMA_CONFIG, 0xffffff04);
	reg_write(dev, DMA_CHANNEL_TIMEOUT, 0x140c8584);
	reg_write(dev, DMA_TIMER_INTERVAL, dma_interval);

	spin_lock_init(&dev->lock);

	timer_setup(&dev->dma_delay_timer, tw686x_dma_delay, 0);

	/*
	* This must be set right before initializing v4l2_dev.
	* It's used to release resources after the last handle
	* held is released.
	*/
	dev->v4l2_dev.release = tw686x_dev_release;
	err = tw686x_video_init(dev);
	if (err) {
	dev_err(&pci_dev->dev, "can't register video\n");
	goto iounmap;
	}

	err = tw686x_audio_init(dev);
	if (err)
	dev_warn(&pci_dev->dev, "can't register audio\n");

	err = request_irq(pci_dev->irq, tw686x_irq, IRQF_SHARED,
	dev->name, dev);
	if (err < 0) {
	dev_err(&pci_dev->dev, "unable to request interrupt\n");
	goto tw686x_free;
	}

	pci_set_drvdata(pci_dev, dev);
	return 0;

	tw686x_free:
	tw686x_video_free(dev);
	tw686x_audio_free(dev);
	iounmap:
	pci_iounmap(pci_dev, dev->mmio);
	free_region:
	pci_release_regions(pci_dev);
	disable_pci:
	pci_disable_device(pci_dev);
	free_audio:
	kfree(dev->audio_channels);
	free_video:
	kfree(dev->video_channels);
	free_dev:
	kfree(dev);
	return err;
	}

	static void tw686x_remove(struct pci_dev *pci_dev)
	{
	struct tw686x_dev *dev = pci_get_drvdata(pci_dev);
	unsigned long flags;

	/* This guarantees the IRQ handler is no longer running,
	* which means we can kiss good-bye some resources.
	*/
	free_irq(pci_dev->irq, dev);

	tw686x_video_free(dev);
	tw686x_audio_free(dev);
	del_timer_sync(&dev->dma_delay_timer);

	pci_iounmap(pci_dev, dev->mmio);
	pci_release_regions(pci_dev);
	pci_disable_device(pci_dev);

	/*
	* Setting pci_dev to NULL allows to detect hardware is no longer
	* available and will be used by vb2_ops. This is required because
	* the device sometimes hot-unplugs itself as the result of a PCIe
	* link down.
	* The lock is really important here.
	*/
	spin_lock_irqsave(&dev->lock, flags);
	dev->pci_dev = NULL;
	spin_unlock_irqrestore(&dev->lock, flags);

	/*
	* This calls tw686x_dev_release if it's the last reference.
	* Otherwise, release is postponed until there are no users left.
	*/
	v4l2_device_put(&dev->v4l2_dev);
	}

	/*
	* On TW6864 and TW6868, all channels share the pair of video DMA SG tables,
	* with 10-bit start_idx and end_idx determining start and end of frame buffer
	* for particular channel.
	* TW6868 with all its 8 channels would be problematic (only 127 SG entries per
	* channel) but we support only 4 channels on this chip anyway (the first
	* 4 channels are driven with internal video decoder, the other 4 would require
	* an external TW286x part).
	*
	* On TW6865 and TW6869, each channel has its own DMA SG table, with indexes
	* starting with 0. Both chips have complete sets of internal video decoders
	* (respectively 4 or 8-channel).
	*
	* All chips have separate SG tables for two video frames.
	*/

	/* driver_data is number of A/V channels */
	static const struct pci_device_id tw686x_pci_tbl[] = {
	{
	PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6864),
	.driver_data = 4
	},
	{
	PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6865), /* not tested */
	.driver_data = 4 \| TYPE_SECOND_GEN
	},
	/*
	* TW6868 supports 8 A/V channels with an external TW2865 chip;
	* not supported by the driver.
	*/
	{
	PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6868), /* not tested */
	.driver_data = 4
	},
	{
	PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6869),
	.driver_data = 8 \| TYPE_SECOND_GEN},
	{}
	};
	MODULE_DEVICE_TABLE(pci, tw686x_pci_tbl);

	static struct pci_driver tw686x_pci_driver = {
	.name = "tw686x",
	.id_table = tw686x_pci_tbl,
	.probe = tw686x_probe,
	.remove = tw686x_remove,
	};
	module_pci_driver(tw686x_pci_driver);

	MODULE_DESCRIPTION("Driver for video frame grabber cards based on Intersil/Techwell TW686[4589]");
	MODULE_AUTHOR("Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>");
	MODULE_AUTHOR("Krzysztof Ha?asa <khalasa@piap.pl>");
	MODULE_LICENSE("GPL v2");