[media] media: Support Intersil/Techwell TW686x-based video capture cards

This commit introduces the support for the Techwell TW686x video
capture IC. This hardware supports a few DMA modes, including
scatter-gather and frame (contiguous).

This commit makes little use of the DMA engine and instead has
a memcpy based implementation. DMA frame and scatter-gather modes
support may be added in the future.

Currently supported chips:
- TW6864 (4 video channels),
- TW6865 (4 video channels, not tested, second generation chip),
- TW6868 (8 video channels but only 4 first channels using
           built-in video decoder are supported, not tested),
- TW6869 (8 video channels, second generation chip).

[mchehab@osg.samsung.com: make checkpatch happy by using "unsigned int"
  instead  of just "unsigned"]
Cc: Krzysztof Halasa <khalasa@piap.pl>
Signed-off-by: NEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Tested-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

MAINTAINERS

@@ -11258,6 +11258,14 @@ W:	https://linuxtv.org
 S:	Odd Fixes
 F:	drivers/media/pci/tw68/
 
+TW686X VIDEO4LINUX DRIVER
+M:	Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
+L:	linux-media@vger.kernel.org
+T:	git git://linuxtv.org/media_tree.git
+W:	http://linuxtv.org
+S:	Maintained
+F:	drivers/media/pci/tw686x/
+
 TPM DEVICE DRIVER
 M:	Peter Huewe <peterhuewe@gmx.de>
 M:	Marcel Selhorst <tpmdd@selhorst.net>

drivers/media/pci/Kconfig

@@ -14,6 +14,7 @@ source "drivers/media/pci/meye/Kconfig"
 source "drivers/media/pci/solo6x10/Kconfig"
 source "drivers/media/pci/sta2x11/Kconfig"
 source "drivers/media/pci/tw68/Kconfig"
+source "drivers/media/pci/tw686x/Kconfig"
 source "drivers/media/pci/zoran/Kconfig"
 endif
 

drivers/media/pci/Makefile

@@ -25,6 +25,7 @@ obj-$(CONFIG_VIDEO_BT848) += bt8xx/
 obj-$(CONFIG_VIDEO_SAA7134) += saa7134/
 obj-$(CONFIG_VIDEO_SAA7164) += saa7164/
 obj-$(CONFIG_VIDEO_TW68) += tw68/
+obj-$(CONFIG_VIDEO_TW686X) += tw686x/
 obj-$(CONFIG_VIDEO_DT3155) += dt3155/
 obj-$(CONFIG_VIDEO_MEYE) += meye/
 obj-$(CONFIG_STA2X11_VIP) += sta2x11/

drivers/media/pci/tw686x/Kconfig

+config VIDEO_TW686X
+	tristate "Intersil/Techwell TW686x video capture cards"
+	depends on PCI && VIDEO_DEV && VIDEO_V4L2 && SND
+	depends on HAS_DMA
+	select VIDEOBUF2_VMALLOC
+	select SND_PCM
+	help
+	  Support for Intersil/Techwell TW686x-based frame grabber cards.
+
+	  Currently supported chips:
+	  - TW6864 (4 video channels),
+	  - TW6865 (4 video channels, not tested, second generation chip),
+	  - TW6868 (8 video channels but only 4 first channels using
+	    built-in video decoder are supported, not tested),
+	  - TW6869 (8 video channels, second generation chip).
+
+	  To compile this driver as a module, choose M here: the module
+	  will be named tw686x.

drivers/media/pci/tw686x/Makefile

+tw686x-objs := tw686x-core.o tw686x-video.o tw686x-audio.o
+
+obj-$(CONFIG_VIDEO_TW686X) += tw686x.o

drivers/media/pci/tw686x/tw686x-audio.c

+/*
+ * Copyright (C) 2015 VanguardiaSur - www.vanguardiasur.com.ar
+ *
+ * Based on the audio support from the tw6869 driver:
+ * Copyright 2015 www.starterkit.ru <info@starterkit.ru>
+ *
+ * Based on:
+ * Driver for Intersil|Techwell TW6869 based DVR cards
+ * (c) 2011-12 liran <jli11@intersil.com> [Intersil|Techwell China]
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kmod.h>
+#include <linux/mutex.h>
+#include <linux/pci.h>
+#include <linux/delay.h>
+
+#include <sound/core.h>
+#include <sound/initval.h>
+#include <sound/pcm.h>
+#include <sound/control.h>
+#include "tw686x.h"
+#include "tw686x-regs.h"
+
+#define AUDIO_CHANNEL_OFFSET 8
+
+void tw686x_audio_irq(struct tw686x_dev *dev, unsigned long requests,
+		      unsigned int pb_status)
+{
+	unsigned long flags;
+	unsigned int ch, pb;
+
+	for_each_set_bit(ch, &requests, max_channels(dev)) {
+		struct tw686x_audio_channel *ac = &dev->audio_channels[ch];
+		struct tw686x_audio_buf *done = NULL;
+		struct tw686x_audio_buf *next = NULL;
+		struct tw686x_dma_desc *desc;
+
+		pb = !!(pb_status & BIT(AUDIO_CHANNEL_OFFSET + ch));
+
+		spin_lock_irqsave(&ac->lock, flags);
+
+		/* Sanity check */
+		if (!ac->ss || !ac->curr_bufs[0] || !ac->curr_bufs[1]) {
+			spin_unlock_irqrestore(&ac->lock, flags);
+			continue;
+		}
+
+		if (!list_empty(&ac->buf_list)) {
+			next = list_first_entry(&ac->buf_list,
+					struct tw686x_audio_buf, list);
+			list_move_tail(&next->list, &ac->buf_list);
+			done = ac->curr_bufs[!pb];
+			ac->curr_bufs[pb] = next;
+		}
+		spin_unlock_irqrestore(&ac->lock, flags);
+
+		desc = &ac->dma_descs[pb];
+		if (done && next && desc->virt) {
+			memcpy(done->virt, desc->virt, desc->size);
+			ac->ptr = done->dma - ac->buf[0].dma;
+			snd_pcm_period_elapsed(ac->ss);
+		}
+	}
+}
+
+static int tw686x_pcm_hw_params(struct snd_pcm_substream *ss,
+				struct snd_pcm_hw_params *hw_params)
+{
+	return snd_pcm_lib_malloc_pages(ss, params_buffer_bytes(hw_params));
+}
+
+static int tw686x_pcm_hw_free(struct snd_pcm_substream *ss)
+{
+	return snd_pcm_lib_free_pages(ss);
+}
+
+/*
+ * The audio device rate is global and shared among all
+ * capture channels. The driver makes no effort to prevent
+ * rate modifications. User is free change the rate, but it
+ * means changing the rate for all capture sub-devices.
+ */
+static const struct snd_pcm_hardware tw686x_capture_hw = {
+	.info			= (SNDRV_PCM_INFO_MMAP |
+				   SNDRV_PCM_INFO_INTERLEAVED |
+				   SNDRV_PCM_INFO_BLOCK_TRANSFER |
+				   SNDRV_PCM_INFO_MMAP_VALID),
+	.formats		= SNDRV_PCM_FMTBIT_S16_LE,
+	.rates			= SNDRV_PCM_RATE_8000_48000,
+	.rate_min		= 8000,
+	.rate_max		= 48000,
+	.channels_min		= 1,
+	.channels_max		= 1,
+	.buffer_bytes_max	= TW686X_AUDIO_PAGE_MAX * TW686X_AUDIO_PAGE_SZ,
+	.period_bytes_min	= TW686X_AUDIO_PAGE_SZ,
+	.period_bytes_max	= TW686X_AUDIO_PAGE_SZ,
+	.periods_min		= TW686X_AUDIO_PERIODS_MIN,
+	.periods_max		= TW686X_AUDIO_PERIODS_MAX,
+};
+
+static int tw686x_pcm_open(struct snd_pcm_substream *ss)
+{
+	struct tw686x_dev *dev = snd_pcm_substream_chip(ss);
+	struct tw686x_audio_channel *ac = &dev->audio_channels[ss->number];
+	struct snd_pcm_runtime *rt = ss->runtime;
+	int err;
+
+	ac->ss = ss;
+	rt->hw = tw686x_capture_hw;
+
+	err = snd_pcm_hw_constraint_integer(rt, SNDRV_PCM_HW_PARAM_PERIODS);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int tw686x_pcm_close(struct snd_pcm_substream *ss)
+{
+	struct tw686x_dev *dev = snd_pcm_substream_chip(ss);
+	struct tw686x_audio_channel *ac = &dev->audio_channels[ss->number];
+
+	ac->ss = NULL;
+	return 0;
+}
+
+static int tw686x_pcm_prepare(struct snd_pcm_substream *ss)
+{
+	struct tw686x_dev *dev = snd_pcm_substream_chip(ss);
+	struct tw686x_audio_channel *ac = &dev->audio_channels[ss->number];
+	struct snd_pcm_runtime *rt = ss->runtime;
+	unsigned int period_size = snd_pcm_lib_period_bytes(ss);
+	struct tw686x_audio_buf *p_buf, *b_buf;
+	unsigned long flags;
+	int i;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	tw686x_disable_channel(dev, AUDIO_CHANNEL_OFFSET + ac->ch);
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	if (dev->audio_rate != rt->rate) {
+		u32 reg;
+
+		dev->audio_rate = rt->rate;
+		reg = ((125000000 / rt->rate) << 16) +
+		       ((125000000 % rt->rate) << 16) / rt->rate;
+
+		reg_write(dev, AUDIO_CONTROL2, reg);
+	}
+
+	if (period_size != TW686X_AUDIO_PAGE_SZ ||
+	    rt->periods < TW686X_AUDIO_PERIODS_MIN ||
+	    rt->periods > TW686X_AUDIO_PERIODS_MAX) {
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&ac->lock, flags);
+	INIT_LIST_HEAD(&ac->buf_list);
+
+	for (i = 0; i < rt->periods; i++) {
+		ac->buf[i].dma = rt->dma_addr + period_size * i;
+		ac->buf[i].virt = rt->dma_area + period_size * i;
+		INIT_LIST_HEAD(&ac->buf[i].list);
+		list_add_tail(&ac->buf[i].list, &ac->buf_list);
+	}
+
+	p_buf =	list_first_entry(&ac->buf_list, struct tw686x_audio_buf, list);
+	list_move_tail(&p_buf->list, &ac->buf_list);
+
+	b_buf =	list_first_entry(&ac->buf_list, struct tw686x_audio_buf, list);
+	list_move_tail(&b_buf->list, &ac->buf_list);
+
+	ac->curr_bufs[0] = p_buf;
+	ac->curr_bufs[1] = b_buf;
+	ac->ptr = 0;
+	spin_unlock_irqrestore(&ac->lock, flags);
+
+	return 0;
+}
+
+static int tw686x_pcm_trigger(struct snd_pcm_substream *ss, int cmd)
+{
+	struct tw686x_dev *dev = snd_pcm_substream_chip(ss);
+	struct tw686x_audio_channel *ac = &dev->audio_channels[ss->number];
+	unsigned long flags;
+	int err = 0;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+		if (ac->curr_bufs[0] && ac->curr_bufs[1]) {
+			spin_lock_irqsave(&dev->lock, flags);
+			tw686x_enable_channel(dev,
+				AUDIO_CHANNEL_OFFSET + ac->ch);
+			spin_unlock_irqrestore(&dev->lock, flags);
+
+			mod_timer(&dev->dma_delay_timer,
+				  jiffies + msecs_to_jiffies(100));
+		} else {
+			err = -EIO;
+		}
+		break;
+	case SNDRV_PCM_TRIGGER_STOP:
+		spin_lock_irqsave(&dev->lock, flags);
+		tw686x_disable_channel(dev, AUDIO_CHANNEL_OFFSET + ac->ch);
+		spin_unlock_irqrestore(&dev->lock, flags);
+
+		spin_lock_irqsave(&ac->lock, flags);
+		ac->curr_bufs[0] = NULL;
+		ac->curr_bufs[1] = NULL;
+		spin_unlock_irqrestore(&ac->lock, flags);
+		break;
+	default:
+		err = -EINVAL;
+	}
+	return err;
+}
+
+static snd_pcm_uframes_t tw686x_pcm_pointer(struct snd_pcm_substream *ss)
+{
+	struct tw686x_dev *dev = snd_pcm_substream_chip(ss);
+	struct tw686x_audio_channel *ac = &dev->audio_channels[ss->number];
+
+	return bytes_to_frames(ss->runtime, ac->ptr);
+}
+
+static struct snd_pcm_ops tw686x_pcm_ops = {
+	.open = tw686x_pcm_open,
+	.close = tw686x_pcm_close,
+	.ioctl = snd_pcm_lib_ioctl,
+	.hw_params = tw686x_pcm_hw_params,
+	.hw_free = tw686x_pcm_hw_free,
+	.prepare = tw686x_pcm_prepare,
+	.trigger = tw686x_pcm_trigger,
+	.pointer = tw686x_pcm_pointer,
+};
+
+static int tw686x_snd_pcm_init(struct tw686x_dev *dev)
+{
+	struct snd_card *card = dev->snd_card;
+	struct snd_pcm *pcm;
+	struct snd_pcm_substream *ss;
+	unsigned int i;
+	int err;
+
+	err = snd_pcm_new(card, card->driver, 0, 0, max_channels(dev), &pcm);
+	if (err < 0)
+		return err;
+
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &tw686x_pcm_ops);
+	snd_pcm_chip(pcm) = dev;
+	pcm->info_flags = 0;
+	strlcpy(pcm->name, "tw686x PCM", sizeof(pcm->name));
+
+	for (i = 0, ss = pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream;
+	     ss; ss = ss->next, i++)
+		snprintf(ss->name, sizeof(ss->name), "vch%u audio", i);
+
+	return snd_pcm_lib_preallocate_pages_for_all(pcm,
+				SNDRV_DMA_TYPE_DEV,
+				snd_dma_pci_data(dev->pci_dev),
+				TW686X_AUDIO_PAGE_MAX * TW686X_AUDIO_PAGE_SZ,
+				TW686X_AUDIO_PAGE_MAX * TW686X_AUDIO_PAGE_SZ);
+}
+
+static void tw686x_audio_dma_free(struct tw686x_dev *dev,
+				  struct tw686x_audio_channel *ac)
+{
+	int pb;
+
+	for (pb = 0; pb < 2; pb++) {
+		if (!ac->dma_descs[pb].virt)
+			continue;
+		pci_free_consistent(dev->pci_dev, ac->dma_descs[pb].size,
+				    ac->dma_descs[pb].virt,
+				    ac->dma_descs[pb].phys);
+		ac->dma_descs[pb].virt = NULL;
+	}
+}
+
+static int tw686x_audio_dma_alloc(struct tw686x_dev *dev,
+				  struct tw686x_audio_channel *ac)
+{
+	int pb;
+
+	for (pb = 0; pb < 2; pb++) {
+		u32 reg = pb ? ADMA_B_ADDR[ac->ch] : ADMA_P_ADDR[ac->ch];
+		void *virt;
+
+		virt = pci_alloc_consistent(dev->pci_dev, TW686X_AUDIO_PAGE_SZ,
+					    &ac->dma_descs[pb].phys);
+		if (!virt) {
+			dev_err(&dev->pci_dev->dev,
+				"dma%d: unable to allocate audio DMA %s-buffer\n",
+				ac->ch, pb ? "B" : "P");
+			return -ENOMEM;
+		}
+		ac->dma_descs[pb].virt = virt;
+		ac->dma_descs[pb].size = TW686X_AUDIO_PAGE_SZ;
+		reg_write(dev, reg, ac->dma_descs[pb].phys);
+	}
+	return 0;
+}
+
+void tw686x_audio_free(struct tw686x_dev *dev)
+{
+	unsigned long flags;
+	u32 dma_ch_mask;
+	u32 dma_cmd;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	dma_cmd = reg_read(dev, DMA_CMD);
+	dma_ch_mask = reg_read(dev, DMA_CHANNEL_ENABLE);
+	reg_write(dev, DMA_CMD, dma_cmd & ~0xff00);
+	reg_write(dev, DMA_CHANNEL_ENABLE, dma_ch_mask & ~0xff00);
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	if (!dev->snd_card)
+		return;
+	snd_card_free(dev->snd_card);
+	dev->snd_card = NULL;
+}
+
+int tw686x_audio_init(struct tw686x_dev *dev)
+{
+	struct pci_dev *pci_dev = dev->pci_dev;
+	struct snd_card *card;
+	int err, ch;
+
+	/*
+	 * AUDIO_CONTROL1
+	 * DMA byte length [31:19] = 4096 (i.e. ALSA period)
+	 * External audio enable [0] = enabled
+	 */
+	reg_write(dev, AUDIO_CONTROL1, 0x80000001);
+
+	err = snd_card_new(&pci_dev->dev, SNDRV_DEFAULT_IDX1,
+			   SNDRV_DEFAULT_STR1,
+			   THIS_MODULE, 0, &card);
+	if (err < 0)
+		return err;
+
+	dev->snd_card = card;
+	strlcpy(card->driver, "tw686x", sizeof(card->driver));
+	strlcpy(card->shortname, "tw686x", sizeof(card->shortname));
+	strlcpy(card->longname, pci_name(pci_dev), sizeof(card->longname));
+	snd_card_set_dev(card, &pci_dev->dev);
+
+	for (ch = 0; ch < max_channels(dev); ch++) {
+		struct tw686x_audio_channel *ac;
+
+		ac = &dev->audio_channels[ch];
+		spin_lock_init(&ac->lock);
+		ac->dev = dev;
+		ac->ch = ch;
+
+		err = tw686x_audio_dma_alloc(dev, ac);
+		if (err < 0)
+			goto err_cleanup;
+	}
+
+	err = tw686x_snd_pcm_init(dev);
+	if (err < 0)
+		goto err_cleanup;
+
+	err = snd_card_register(card);
+	if (!err)
+		return 0;
+
+err_cleanup:
+	for (ch = 0; ch < max_channels(dev); ch++) {
+		if (!dev->audio_channels[ch].dev)
+			continue;
+		tw686x_audio_dma_free(dev, &dev->audio_channels[ch]);
+	}
+	snd_card_free(card);
+	dev->snd_card = NULL;
+	return err;
+}

drivers/media/pci/tw686x/tw686x-core.c

+/*
+ * 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
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ *
+ * 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.
+ * This driver tries to access hardware registers as infrequently
+ * as possible by:
+ *   i.  allocating fixed DMA buffers and memcpy'ing into
+ *       vmalloc'ed buffers
+ *   ii. using a timer to mitigate the rate of DMA reset operations,
+ *       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");
+
+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(unsigned long data)
+{
+	struct tw686x_dev *dev = (struct tw686x_dev *)data;
+	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;
+	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\n", dev->name,
+		pci_name(pci_dev), pci_dev->irq,
+		(unsigned long)pci_resource_start(pci_dev, 0));
+
+	dev->pci_dev = pci_dev;
+	if (pci_enable_device(pci_dev)) {
+		err = -EIO;
+		goto free_audio;
+	}
+
+	pci_set_master(pci_dev);
+	err = pci_set_dma_mask(pci_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);
+
+	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 iounmap;
+	}
+
+	setup_timer(&dev->dma_delay_timer,
+		    tw686x_dma_delay, (unsigned long) dev);
+
+	/*
+	 * 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 free_irq;
+	}
+
+	err = tw686x_audio_init(dev);
+	if (err)
+		dev_warn(&pci_dev->dev, "can't register audio\n");
+
+	pci_set_drvdata(pci_dev, dev);
+	return 0;
+
+free_irq:
+	free_irq(pci_dev->irq, 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");

drivers/media/pci/tw686x/tw686x-regs.h

+/* DMA controller registers */
+#define REG8_1(a0) ((const u16[8]) { a0, a0 + 1, a0 + 2, a0 + 3, \
+				     a0 + 4, a0 + 5, a0 + 6, a0 + 7})
+#define REG8_2(a0) ((const u16[8]) { a0, a0 + 2, a0 + 4, a0 + 6,	\
+				     a0 + 8, a0 + 0xa, a0 + 0xc, a0 + 0xe})
+#define REG8_8(a0) ((const u16[8]) { a0, a0 + 8, a0 + 0x10, a0 + 0x18, \
+				     a0 + 0x20, a0 + 0x28, a0 + 0x30, \
+				     a0 + 0x38})
+#define INT_STATUS		0x00
+#define PB_STATUS		0x01
+#define DMA_CMD			0x02
+#define VIDEO_FIFO_STATUS	0x03
+#define VIDEO_CHANNEL_ID	0x04
+#define VIDEO_PARSER_STATUS	0x05
+#define SYS_SOFT_RST		0x06
+#define DMA_PAGE_TABLE0_ADDR	((const u16[8]) { 0x08, 0xd0, 0xd2, 0xd4, \
+						  0xd6, 0xd8, 0xda, 0xdc })
+#define DMA_PAGE_TABLE1_ADDR	((const u16[8]) { 0x09, 0xd1, 0xd3, 0xd5, \
+						  0xd7, 0xd9, 0xdb, 0xdd })
+#define DMA_CHANNEL_ENABLE	0x0a
+#define DMA_CONFIG		0x0b
+#define DMA_TIMER_INTERVAL	0x0c
+#define DMA_CHANNEL_TIMEOUT	0x0d
+#define VDMA_CHANNEL_CONFIG	REG8_1(0x10)
+#define ADMA_P_ADDR		REG8_2(0x18)
+#define ADMA_B_ADDR		REG8_2(0x19)
+#define DMA10_P_ADDR		0x28
+#define DMA10_B_ADDR		0x29
+#define VIDEO_CONTROL1		0x2a
+#define VIDEO_CONTROL2		0x2b
+#define AUDIO_CONTROL1		0x2c
+#define AUDIO_CONTROL2		0x2d
+#define PHASE_REF		0x2e
+#define GPIO_REG		0x2f
+#define INTL_HBAR_CTRL		REG8_1(0x30)
+#define AUDIO_CONTROL3		0x38
+#define VIDEO_FIELD_CTRL	REG8_1(0x39)
+#define HSCALER_CTRL		REG8_1(0x42)
+#define VIDEO_SIZE		REG8_1(0x4A)
+#define VIDEO_SIZE_F2		REG8_1(0x52)
+#define MD_CONF			REG8_1(0x60)
+#define MD_INIT			REG8_1(0x68)
+#define MD_MAP0			REG8_1(0x70)
+#define VDMA_P_ADDR		REG8_8(0x80) /* not used in DMA SG mode */
+#define VDMA_WHP		REG8_8(0x81)
+#define VDMA_B_ADDR		REG8_8(0x82)
+#define VDMA_F2_P_ADDR		REG8_8(0x84)
+#define VDMA_F2_WHP		REG8_8(0x85)
+#define VDMA_F2_B_ADDR		REG8_8(0x86)
+#define EP_REG_ADDR		0xfe
+#define EP_REG_DATA		0xff
+
+/* Video decoder registers */
+#define VDREG8(a0) ((const u16[8]) { \
+	a0 + 0x000, a0 + 0x010, a0 + 0x020, a0 + 0x030,	\
+	a0 + 0x100, a0 + 0x110, a0 + 0x120, a0 + 0x130})
+#define VIDSTAT			VDREG8(0x100)
+#define BRIGHT			VDREG8(0x101)
+#define CONTRAST		VDREG8(0x102)
+#define SHARPNESS		VDREG8(0x103)
+#define SAT_U			VDREG8(0x104)
+#define SAT_V			VDREG8(0x105)
+#define HUE			VDREG8(0x106)
+#define CROP_HI			VDREG8(0x107)
+#define VDELAY_LO		VDREG8(0x108)
+#define VACTIVE_LO		VDREG8(0x109)
+#define HDELAY_LO		VDREG8(0x10a)
+#define HACTIVE_LO		VDREG8(0x10b)
+#define MVSN			VDREG8(0x10c)
+#define STATUS2			VDREG8(0x10d)
+#define SDT			VDREG8(0x10e)
+#define SDT_EN			VDREG8(0x10f)
+
+#define VSCALE_LO		VDREG8(0x144)
+#define SCALE_HI		VDREG8(0x145)
+#define HSCALE_LO		VDREG8(0x146)
+#define F2CROP_HI		VDREG8(0x147)
+#define F2VDELAY_LO		VDREG8(0x148)
+#define F2VACTIVE_LO		VDREG8(0x149)
+#define F2HDELAY_LO		VDREG8(0x14a)
+#define F2HACTIVE_LO		VDREG8(0x14b)
+#define F2VSCALE_LO		VDREG8(0x14c)
+#define F2SCALE_HI		VDREG8(0x14d)
+#define F2HSCALE_LO		VDREG8(0x14e)
+#define F2CNT			VDREG8(0x14f)
+
+#define VDREG2(a0) ((const u16[2]) { a0, a0 + 0x100 })
+#define SRST			VDREG2(0x180)
+#define ACNTL			VDREG2(0x181)
+#define ACNTL2			VDREG2(0x182)
+#define CNTRL1			VDREG2(0x183)
+#define CKHY			VDREG2(0x184)
+#define SHCOR			VDREG2(0x185)
+#define CORING			VDREG2(0x186)
+#define CLMPG			VDREG2(0x187)
+#define IAGC			VDREG2(0x188)
+#define VCTRL1			VDREG2(0x18f)
+#define MISC1			VDREG2(0x194)
+#define LOOP			VDREG2(0x195)
+#define MISC2			VDREG2(0x196)
+
+#define CLMD			VDREG2(0x197)
+#define ANPWRDOWN		VDREG2(0x1ce)
+#define AIGAIN			((const u16[8]) { 0x1d0, 0x1d1, 0x1d2, 0x1d3, \
+						  0x2d0, 0x2d1, 0x2d2, 0x2d3 })
+
+#define SYS_MODE_DMA_SHIFT	13
+
+#define DMA_CMD_ENABLE		BIT(31)
+#define INT_STATUS_DMA_TOUT	BIT(17)
+#define TW686X_VIDSTAT_HLOCK	BIT(6)
+#define TW686X_VIDSTAT_VDLOSS	BIT(7)
+
+#define TW686X_STD_NTSC_M	0
+#define TW686X_STD_PAL		1
+#define TW686X_STD_SECAM	2
+#define TW686X_STD_NTSC_443	3
+#define TW686X_STD_PAL_M	4
+#define TW686X_STD_PAL_CN	5
+#define TW686X_STD_PAL_60	6
+
+#define TW686X_FIFO_ERROR(x)	(x & ~(0xff))

drivers/media/pci/tw686x/tw686x.h

+/*
+ * Copyright (C) 2015 VanguardiaSur - www.vanguardiasur.com.ar
+ *
+ * Copyright (C) 2015 Industrial Research Institute for Automation
+ * and Measurements PIAP
+ * Written by Krzysztof Ha?asa
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ */
+
+#include <linux/mutex.h>
+#include <linux/pci.h>
+#include <linux/timer.h>
+#include <linux/videodev2.h>
+#include <media/v4l2-common.h>
+#include <media/v4l2-ctrls.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-ioctl.h>
+#include <media/videobuf2-v4l2.h>
+#include <sound/pcm.h>
+
+#include "tw686x-regs.h"
+
+#define TYPE_MAX_CHANNELS	0x0f
+#define TYPE_SECOND_GEN		0x10
+#define TW686X_DEF_PHASE_REF	0x1518
+
+#define TW686X_FIELD_MODE	0x3
+#define TW686X_FRAME_MODE	0x2
+/* 0x1 is reserved */
+#define TW686X_SG_MODE		0x0
+
+#define TW686X_AUDIO_PAGE_SZ		4096
+#define TW686X_AUDIO_PAGE_MAX		16
+#define TW686X_AUDIO_PERIODS_MIN	2
+#define TW686X_AUDIO_PERIODS_MAX	TW686X_AUDIO_PAGE_MAX
+
+struct tw686x_format {
+	char *name;
+	unsigned int fourcc;
+	unsigned int depth;
+	unsigned int mode;
+};
+
+struct tw686x_dma_desc {
+	dma_addr_t phys;
+	void *virt;
+	unsigned int size;
+};
+
+struct tw686x_audio_buf {
+	dma_addr_t dma;
+	void *virt;
+	struct list_head list;
+};
+
+struct tw686x_v4l2_buf {
+	struct vb2_v4l2_buffer vb;
+	struct list_head list;
+};
+
+struct tw686x_audio_channel {
+	struct tw686x_dev *dev;
+	struct snd_pcm_substream *ss;
+	unsigned int ch;
+	struct tw686x_audio_buf *curr_bufs[2];
+	struct tw686x_dma_desc dma_descs[2];
+	dma_addr_t ptr;
+
+	struct tw686x_audio_buf buf[TW686X_AUDIO_PAGE_MAX];
+	struct list_head buf_list;
+	spinlock_t lock;
+};
+
+struct tw686x_video_channel {
+	struct tw686x_dev *dev;
+
+	struct vb2_queue vidq;
+	struct list_head vidq_queued;
+	struct video_device *device;
+	struct tw686x_v4l2_buf *curr_bufs[2];
+	struct tw686x_dma_desc dma_descs[2];
+
+	struct v4l2_ctrl_handler ctrl_handler;
+	const struct tw686x_format *format;
+	struct mutex vb_mutex;
+	spinlock_t qlock;
+	v4l2_std_id video_standard;
+	unsigned int width, height;
+	unsigned int h_halve, v_halve;
+	unsigned int ch;
+	unsigned int num;
+	unsigned int fps;
+	unsigned int input;
+	unsigned int sequence;
+	unsigned int pb;
+	bool no_signal;
+};
+
+/**
+ * struct tw686x_dev - global device status
+ * @lock: spinlock controlling access to the
+ *        shared device registers (DMA enable/disable).
+ */
+struct tw686x_dev {
+	spinlock_t lock;
+
+	struct v4l2_device v4l2_dev;
+	struct snd_card *snd_card;
+
+	char name[32];
+	unsigned int type;
+	struct pci_dev *pci_dev;
+	__u32 __iomem *mmio;
+
+	void *alloc_ctx;
+
+	struct tw686x_video_channel *video_channels;
+	struct tw686x_audio_channel *audio_channels;
+
+	int audio_rate; /* per-device value */
+
+	struct timer_list dma_delay_timer;
+	u32 pending_dma_en; /* must be protected by lock */
+	u32 pending_dma_cmd; /* must be protected by lock */
+};
+
+static inline uint32_t reg_read(struct tw686x_dev *dev, unsigned int reg)
+{
+	return readl(dev->mmio + reg);
+}
+
+static inline void reg_write(struct tw686x_dev *dev, unsigned int reg,
+			     uint32_t value)
+{
+	writel(value, dev->mmio + reg);
+}
+
+static inline unsigned int max_channels(struct tw686x_dev *dev)
+{
+	return dev->type & TYPE_MAX_CHANNELS; /* 4 or 8 channels */
+}
+
+void tw686x_enable_channel(struct tw686x_dev *dev, unsigned int channel);
+void tw686x_disable_channel(struct tw686x_dev *dev, unsigned int channel);
+
+int tw686x_video_init(struct tw686x_dev *dev);
+void tw686x_video_free(struct tw686x_dev *dev);
+void tw686x_video_irq(struct tw686x_dev *dev, unsigned long requests,
+		      unsigned int pb_status, unsigned int fifo_status,
+		      unsigned int *reset_ch);
+
+int tw686x_audio_init(struct tw686x_dev *dev);
+void tw686x_audio_free(struct tw686x_dev *dev);
+void tw686x_audio_irq(struct tw686x_dev *dev, unsigned long requests,
+		      unsigned int pb_status);