text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   *  TW5864 driver - core functions
   *
   *  Copyright (C) 2016 Bluecherry, LLC <maintainers@bluecherrydvr.com>
   */
  
  #include <linux/init.h>
  #include <linux/list.h>
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/kmod.h>
  #include <linux/sound.h>
  #include <linux/interrupt.h>
  #include <linux/delay.h>
  #include <linux/dma-mapping.h>
  #include <linux/pm.h>
  #include <linux/pci_ids.h>
  #include <linux/jiffies.h>
  #include <asm/dma.h>
  #include <media/v4l2-dev.h>
  
  #include "tw5864.h"
  #include "tw5864-reg.h"
  
  MODULE_DESCRIPTION("V4L2 driver module for tw5864-based multimedia capture & encoding devices");
  MODULE_AUTHOR("Bluecherry Maintainers <maintainers@bluecherrydvr.com>");
  MODULE_AUTHOR("Andrey Utkin <andrey.utkin@corp.bluecherry.net>");
  MODULE_LICENSE("GPL");
  
  /*
   * BEWARE OF KNOWN ISSUES WITH VIDEO QUALITY
   *
   * This driver was developed by Bluecherry LLC by deducing behaviour of
   * original manufacturer's driver, from both source code and execution traces.
   * It is known that there are some artifacts on output video with this driver:
   *  - on all known hardware samples: random pixels of wrong color (mostly
   *    white, red or blue) appearing and disappearing on sequences of P-frames;
   *  - on some hardware samples (known with H.264 core version e006:2800):
   *    total madness on P-frames: blocks of wrong luminance; blocks of wrong
   *    colors "creeping" across the picture.
   * There is a workaround for both issues: avoid P-frames by setting GOP size
   * to 1. To do that, run this command on device files created by this driver:
   *
   * v4l2-ctl --device /dev/videoX --set-ctrl=video_gop_size=1
   *
   * These issues are not decoding errors; all produced H.264 streams are decoded
   * properly. Streams without P-frames don't have these artifacts so it's not
   * analog-to-digital conversion issues nor internal memory errors; we conclude
   * it's internal H.264 encoder issues.
   * We cannot even check the original driver's behaviour because it has never
   * worked properly at all in our development environment. So these issues may
   * be actually related to firmware or hardware. However it may be that there's
   * just some more register settings missing in the driver which would please
   * the hardware.
   * Manufacturer didn't help much on our inquiries, but feel free to disturb
   * again the support of Intersil (owner of former Techwell).
   */
  
  /* take first free /dev/videoX indexes by default */
  static unsigned int video_nr[] = {[0 ... (TW5864_INPUTS - 1)] = -1 };
  
  module_param_array(video_nr, int, NULL, 0444);
  MODULE_PARM_DESC(video_nr, "video devices numbers array");
  
  /*
   * Please add any new PCI IDs to: http://pci-ids.ucw.cz.  This keeps
   * the PCI ID database up to date.  Note that the entries must be
   * added under vendor 0x1797 (Techwell Inc.) as subsystem IDs.
   */
  static const struct pci_device_id tw5864_pci_tbl[] = {
  	{PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, PCI_DEVICE_ID_TECHWELL_5864)},
  	{0,}
  };
  
  void tw5864_irqmask_apply(struct tw5864_dev *dev)
  {
  	tw_writel(TW5864_INTR_ENABLE_L, dev->irqmask & 0xffff);
  	tw_writel(TW5864_INTR_ENABLE_H, (dev->irqmask >> 16));
  }
  
  static void tw5864_interrupts_disable(struct tw5864_dev *dev)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&dev->slock, flags);
  	dev->irqmask = 0;
  	tw5864_irqmask_apply(dev);
  	spin_unlock_irqrestore(&dev->slock, flags);
  }
  
  static void tw5864_timer_isr(struct tw5864_dev *dev);
  static void tw5864_h264_isr(struct tw5864_dev *dev);
  
  static irqreturn_t tw5864_isr(int irq, void *dev_id)
  {
  	struct tw5864_dev *dev = dev_id;
  	u32 status;
  
  	status = tw_readl(TW5864_INTR_STATUS_L) |
  		tw_readl(TW5864_INTR_STATUS_H) << 16;
  	if (!status)
  		return IRQ_NONE;
  
  	tw_writel(TW5864_INTR_CLR_L, 0xffff);
  	tw_writel(TW5864_INTR_CLR_H, 0xffff);
  
  	if (status & TW5864_INTR_VLC_DONE)
  		tw5864_h264_isr(dev);
  
  	if (status & TW5864_INTR_TIMER)
  		tw5864_timer_isr(dev);
  
  	if (!(status & (TW5864_INTR_TIMER | TW5864_INTR_VLC_DONE))) {
  		dev_dbg(&dev->pci->dev, "Unknown interrupt, status 0x%08X\n",
  			status);
  	}
  
  	return IRQ_HANDLED;
  }
  
  static void tw5864_h264_isr(struct tw5864_dev *dev)
  {
  	int channel = tw_readl(TW5864_DSP) & TW5864_DSP_ENC_CHN;
  	struct tw5864_input *input = &dev->inputs[channel];
  	int cur_frame_index, next_frame_index;
  	struct tw5864_h264_frame *cur_frame, *next_frame;
  	unsigned long flags;
  
  	spin_lock_irqsave(&dev->slock, flags);
  
  	cur_frame_index = dev->h264_buf_w_index;
  	next_frame_index = (cur_frame_index + 1) % H264_BUF_CNT;
  	cur_frame = &dev->h264_buf[cur_frame_index];
  	next_frame = &dev->h264_buf[next_frame_index];
  
  	if (next_frame_index != dev->h264_buf_r_index) {
  		cur_frame->vlc_len = tw_readl(TW5864_VLC_LENGTH) << 2;
  		cur_frame->checksum = tw_readl(TW5864_VLC_CRC_REG);
  		cur_frame->input = input;
  		cur_frame->timestamp = ktime_get_ns();
  		cur_frame->seqno = input->frame_seqno;
  		cur_frame->gop_seqno = input->frame_gop_seqno;
  
  		dev->h264_buf_w_index = next_frame_index;
  		tasklet_schedule(&dev->tasklet);
  
  		cur_frame = next_frame;
  
  		spin_lock(&input->slock);
  		input->frame_seqno++;
  		input->frame_gop_seqno++;
  		if (input->frame_gop_seqno >= input->gop)
  			input->frame_gop_seqno = 0;
  		spin_unlock(&input->slock);
  	} else {
  		dev_err(&dev->pci->dev,
  			"Skipped frame on input %d because all buffers busy\n",
  			channel);
  	}
  
  	dev->encoder_busy = 0;
  
  	spin_unlock_irqrestore(&dev->slock, flags);
  
  	tw_writel(TW5864_VLC_STREAM_BASE_ADDR, cur_frame->vlc.dma_addr);
  	tw_writel(TW5864_MV_STREAM_BASE_ADDR, cur_frame->mv.dma_addr);
  
  	/* Additional ack for this interrupt */
  	tw_writel(TW5864_VLC_DSP_INTR, 0x00000001);
  	tw_writel(TW5864_PCI_INTR_STATUS, TW5864_VLC_DONE_INTR);
  }
  
  static void tw5864_input_deadline_update(struct tw5864_input *input)
  {
  	input->new_frame_deadline = jiffies + msecs_to_jiffies(1000);
  }
  
  static void tw5864_timer_isr(struct tw5864_dev *dev)
  {
  	unsigned long flags;
  	int i;
  	int encoder_busy;
  
  	/* Additional ack for this interrupt */
  	tw_writel(TW5864_PCI_INTR_STATUS, TW5864_TIMER_INTR);
  
  	spin_lock_irqsave(&dev->slock, flags);
  	encoder_busy = dev->encoder_busy;
  	spin_unlock_irqrestore(&dev->slock, flags);
  
  	if (encoder_busy)
  		return;
  
  	/*
  	 * Traversing inputs in round-robin fashion, starting from next to the
  	 * last processed one
  	 */
  	for (i = 0; i < TW5864_INPUTS; i++) {
  		int next_input = (i + dev->next_input) % TW5864_INPUTS;
  		struct tw5864_input *input = &dev->inputs[next_input];
  		int raw_buf_id; /* id of internal buf with last raw frame */
  
  		spin_lock_irqsave(&input->slock, flags);
  		if (!input->enabled)
  			goto next;
  
  		/* Check if new raw frame is available */
  		raw_buf_id = tw_mask_shift_readl(TW5864_SENIF_ORG_FRM_PTR1, 0x3,
  						 2 * input->nr);
  
  		if (input->buf_id != raw_buf_id) {
  			input->buf_id = raw_buf_id;
  			tw5864_input_deadline_update(input);
  			spin_unlock_irqrestore(&input->slock, flags);
  
  			spin_lock_irqsave(&dev->slock, flags);
  			dev->encoder_busy = 1;
  			dev->next_input = (next_input + 1) % TW5864_INPUTS;
  			spin_unlock_irqrestore(&dev->slock, flags);
  
  			tw5864_request_encoded_frame(input);
  			break;
  		}
  
  		/* No new raw frame; check if channel is stuck */
  		if (time_is_after_jiffies(input->new_frame_deadline)) {
  			/* If stuck, request new raw frames again */
  			tw_mask_shift_writel(TW5864_ENC_BUF_PTR_REC1, 0x3,
  					     2 * input->nr, input->buf_id + 3);
  			tw5864_input_deadline_update(input);
  		}
  next:
  		spin_unlock_irqrestore(&input->slock, flags);
  	}
  }
  
  static int tw5864_initdev(struct pci_dev *pci_dev,
  			  const struct pci_device_id *pci_id)
  {
  	struct tw5864_dev *dev;
  	int err;
  
  	dev = devm_kzalloc(&pci_dev->dev, sizeof(*dev), GFP_KERNEL);
  	if (!dev)
  		return -ENOMEM;
  
  	snprintf(dev->name, sizeof(dev->name), "tw5864:%s", pci_name(pci_dev));
  
  	err = v4l2_device_register(&pci_dev->dev, &dev->v4l2_dev);
  	if (err)
  		return err;
  
  	/* pci init */
  	dev->pci = pci_dev;
  	err = pci_enable_device(pci_dev);
  	if (err) {
  		dev_err(&dev->pci->dev, "pci_enable_device() failed\n");
  		goto unreg_v4l2;
  	}
  
  	pci_set_master(pci_dev);
  
  	err = pci_set_dma_mask(pci_dev, DMA_BIT_MASK(32));
  	if (err) {
  		dev_err(&dev->pci->dev, "32 bit PCI DMA is not supported\n");
  		goto disable_pci;
  	}
  
  	/* get mmio */
  	err = pci_request_regions(pci_dev, dev->name);
  	if (err) {
  		dev_err(&dev->pci->dev, "Cannot request regions for MMIO\n");
  		goto disable_pci;
  	}
  	dev->mmio = pci_ioremap_bar(pci_dev, 0);
  	if (!dev->mmio) {
  		err = -EIO;
  		dev_err(&dev->pci->dev, "can't ioremap() MMIO memory\n");
  		goto release_mmio;
  	}
  
  	spin_lock_init(&dev->slock);
  
  	dev_info(&pci_dev->dev, "TW5864 hardware version: %04x\n",
  		 tw_readl(TW5864_HW_VERSION));
  	dev_info(&pci_dev->dev, "TW5864 H.264 core version: %04x:%04x\n",
  		 tw_readl(TW5864_H264REV),
  		 tw_readl(TW5864_UNDECLARED_H264REV_PART2));
  
  	err = tw5864_video_init(dev, video_nr);
  	if (err)
  		goto unmap_mmio;
  
  	/* get irq */
  	err = devm_request_irq(&pci_dev->dev, pci_dev->irq, tw5864_isr,
  			       IRQF_SHARED, "tw5864", dev);
  	if (err < 0) {
  		dev_err(&dev->pci->dev, "can't get IRQ %d\n", pci_dev->irq);
  		goto fini_video;
  	}
  
  	dev_info(&pci_dev->dev, "Note: there are known video quality issues. For details\n");
  	dev_info(&pci_dev->dev, "see the comment in drivers/media/pci/tw5864/tw5864-core.c.\n");
  
  	return 0;
  
  fini_video:
  	tw5864_video_fini(dev);
  unmap_mmio:
  	iounmap(dev->mmio);
  release_mmio:
  	pci_release_regions(pci_dev);
  disable_pci:
  	pci_disable_device(pci_dev);
  unreg_v4l2:
  	v4l2_device_unregister(&dev->v4l2_dev);
  	return err;
  }
  
  static void tw5864_finidev(struct pci_dev *pci_dev)
  {
  	struct v4l2_device *v4l2_dev = pci_get_drvdata(pci_dev);
  	struct tw5864_dev *dev =
  		container_of(v4l2_dev, struct tw5864_dev, v4l2_dev);
  
  	/* shutdown subsystems */
  	tw5864_interrupts_disable(dev);
  
  	/* unregister */
  	tw5864_video_fini(dev);
  
  	/* release resources */
  	iounmap(dev->mmio);
  	release_mem_region(pci_resource_start(pci_dev, 0),
  			   pci_resource_len(pci_dev, 0));
  
  	v4l2_device_unregister(&dev->v4l2_dev);
  	devm_kfree(&pci_dev->dev, dev);
  }
  
  static struct pci_driver tw5864_pci_driver = {
  	.name = "tw5864",
  	.id_table = tw5864_pci_tbl,
  	.probe = tw5864_initdev,
  	.remove = tw5864_finidev,
  };
  
  module_pci_driver(tw5864_pci_driver);
  