Re: [PATCH v2 2/2] v4l: cadence: Add Cadence MIPI-CSI2 RX driver

[Benoit Parrot <bparrot-l0cyMroinI0@public.gmane.org>]

Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> wrote on Thu [2017-Jul-20 11:23:02 +0200]:
> The Cadence CSI-2 RX Controller is an hardware block meant to be used as a
> bridge between a CSI-2 bus and pixel grabbers.
> 
> It supports operating with internal or external D-PHY, with up to 4 lanes,
> or without any D-PHY. The current code only supports the former case.
> 
> It also support dynamic mapping of the CSI-2 virtual channels to the
> associated pixel grabbers, but that isn't allowed at the moment either.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> ---
>  drivers/media/platform/Kconfig               |   1 +
>  drivers/media/platform/Makefile              |   2 +
>  drivers/media/platform/cadence/Kconfig       |  12 +
>  drivers/media/platform/cadence/Makefile      |   1 +
>  drivers/media/platform/cadence/cdns-csi2rx.c | 413 +++++++++++++++++++++++++++
>  5 files changed, 429 insertions(+)
>  create mode 100644 drivers/media/platform/cadence/Kconfig
>  create mode 100644 drivers/media/platform/cadence/Makefile
>  create mode 100644 drivers/media/platform/cadence/cdns-csi2rx.c
> 
> diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> index 1313cd533436..a79d96e9b723 100644
> --- a/drivers/media/platform/Kconfig
> +++ b/drivers/media/platform/Kconfig
> @@ -26,6 +26,7 @@ config VIDEO_VIA_CAMERA
>  #
>  # Platform multimedia device configuration
>  #
> +source "drivers/media/platform/cadence/Kconfig"
>  
>  source "drivers/media/platform/davinci/Kconfig"
>  
> diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
> index 9beadc760467..1d31eb51e9bb 100644
> --- a/drivers/media/platform/Makefile
> +++ b/drivers/media/platform/Makefile
> @@ -2,6 +2,8 @@
>  # Makefile for the video capture/playback device drivers.
>  #
>  
> +obj-$(CONFIG_VIDEO_CADENCE)		+= cadence/
> +
>  obj-$(CONFIG_VIDEO_M32R_AR_M64278) += arv.o
>  
>  obj-$(CONFIG_VIDEO_VIA_CAMERA) += via-camera.o
> diff --git a/drivers/media/platform/cadence/Kconfig b/drivers/media/platform/cadence/Kconfig
> new file mode 100644
> index 000000000000..d1b6bbb6a0eb
> --- /dev/null
> +++ b/drivers/media/platform/cadence/Kconfig
> @@ -0,0 +1,12 @@
> +config VIDEO_CADENCE
> +	bool "Cadence Video Devices"
> +
> +if VIDEO_CADENCE
> +
> +config VIDEO_CADENCE_CSI2RX
> +	tristate "Cadence MIPI-CSI2 RX Controller v1.3"
> +	depends on MEDIA_CONTROLLER
> +	depends on VIDEO_V4L2_SUBDEV_API
> +	select V4L2_FWNODE
> +
> +endif
> diff --git a/drivers/media/platform/cadence/Makefile b/drivers/media/platform/cadence/Makefile
> new file mode 100644
> index 000000000000..99a4086b7448
> --- /dev/null
> +++ b/drivers/media/platform/cadence/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_VIDEO_CADENCE_CSI2RX)	+= cdns-csi2rx.o
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> new file mode 100644
> index 000000000000..9a58f275f53c
> --- /dev/null
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -0,0 +1,413 @@
> +/*
> + * Driver for Cadence MIPI-CSI2 RX Controller v1.3
> + *
> + * Copyright (C) 2017 Cadence Design Systems Inc.
> + *
> + * This program is free software; you can redistribute  it and/or modify it
> + * under  the terms of  the GNU General  Public License as published by the
> + * Free Software Foundation;  either version 2 of the  License, or (at your
> + * option) any later version.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_graph.h>
> +#include <linux/platform_device.h>
> +
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +
> +#define CSI2RX_DEVICE_CFG_REG			0x000
> +
> +#define CSI2RX_SOFT_RESET_REG			0x004
> +#define CSI2RX_SOFT_RESET_PROTOCOL			BIT(1)
> +#define CSI2RX_SOFT_RESET_FRONT				BIT(0)
> +
> +#define CSI2RX_STATIC_CFG_REG			0x008
> +
> +#define CSI2RX_STREAM_BASE(n)		(((n) + 1) * 0x100)
> +
> +#define CSI2RX_STREAM_CTRL_REG(n)		(CSI2RX_STREAM_BASE(n) + 0x000)
> +#define CSI2RX_STREAM_CTRL_START			BIT(0)
> +
> +#define CSI2RX_STREAM_DATA_CFG_REG(n)		(CSI2RX_STREAM_BASE(n) + 0x008)
> +#define CSI2RX_STREAM_DATA_CFG_EN_VC_SELECT		BIT(31)
> +#define CSI2RX_STREAM_DATA_CFG_VC_SELECT(n)		BIT((n) + 16)
> +
> +#define CSI2RX_STREAM_CFG_REG(n)		(CSI2RX_STREAM_BASE(n) + 0x00c)
> +#define CSI2RX_STREAM_CFG_FIFO_MODE_LARGE_BUF		(1 << 8)
> +
> +#define CSI2RX_STREAMS_MAX	4
> +

Just to confirm here that "streams" in this case are equivalent to
"Virtual Channel", correct?

> +enum csi2rx_pads {
> +	CSI2RX_PAD_SINK,
> +	CSI2RX_PAD_SOURCE_VC0,
> +	CSI2RX_PAD_SOURCE_VC1,
> +	CSI2RX_PAD_SOURCE_VC2,
> +	CSI2RX_PAD_SOURCE_VC3,
> +	CSI2RX_PAD_MAX,
> +};
> +
> +struct csi2rx_priv {
> +	struct device		*dev;
> +
> +	void __iomem		*base;
> +	struct clk		*sys_clk;
> +	struct clk		*p_clk;
> +	struct clk		*p_free_clk;
> +	struct clk		*pixel_clk[CSI2RX_STREAMS_MAX];
> +	struct clk		*dphy_rx_clk;
> +
> +	u8			lanes;
> +	u8			max_lanes;
> +	u8			max_streams;
> +	bool			cdns_dphy;
> +
> +	struct v4l2_subdev	subdev;
> +	struct media_pad	pads[CSI2RX_PAD_MAX];
> +
> +	/* Remote sensor */
> +	struct v4l2_async_subdev	asd;
> +	struct device_node		*sensor_node;
> +	struct v4l2_subdev		*sensor_subdev;
> +	int				sensor_pad;
> +};
> +
> +static inline
> +struct csi2rx_priv *v4l2_subdev_to_csi2rx(struct v4l2_subdev *subdev)
> +{
> +	return container_of(subdev, struct csi2rx_priv, subdev);
> +}
> +
> +static void csi2rx_reset(struct csi2rx_priv *csi2rx)
> +{
> +	writel(CSI2RX_SOFT_RESET_PROTOCOL | CSI2RX_SOFT_RESET_FRONT,
> +	       csi2rx->base + CSI2RX_SOFT_RESET_REG);
> +
> +	udelay(10);

Shouldn't we use usleep_range() instead?

> +
> +	writel(0, csi2rx->base + CSI2RX_SOFT_RESET_REG);
> +}
> +
> +static int csi2rx_start(struct csi2rx_priv *csi2rx)
> +{
> +	u32 reg;
> +	int i;
> +
> +	csi2rx_reset(csi2rx);
> +
> +	// TODO: modify the mapping of the DPHY lanes?
> +	reg = readl(csi2rx->base + CSI2RX_STATIC_CFG_REG);
> +	reg &= ~GENMASK(11, 8);
> +	writel(reg | (csi2rx->lanes << 8),
> +	       csi2rx->base + CSI2RX_STATIC_CFG_REG);
> +
> +	/*
> +	 * Create a static mapping between the CSI virtual channels
> +	 * and the output stream.
> +	 *
> +	 * This should be enhanced, but v4l2 lacks the support for
> +	 * changing that mapping dynamically.
> +	 */
> +	for (i = 0; i < csi2rx->max_streams; i++) {
> +		writel(CSI2RX_STREAM_CFG_FIFO_MODE_LARGE_BUF,
> +		       csi2rx->base + CSI2RX_STREAM_CFG_REG(i));
> +
> +		writel(CSI2RX_STREAM_DATA_CFG_EN_VC_SELECT |
> +		       CSI2RX_STREAM_DATA_CFG_VC_SELECT(i),
> +		       csi2rx->base + CSI2RX_STREAM_DATA_CFG_REG(i));
> +
> +		writel(CSI2RX_STREAM_CTRL_START,
> +		       csi2rx->base + CSI2RX_STREAM_CTRL_REG(i));
> +	}
> +
> +	return 0;
> +}
> +
> +static int csi2rx_stop(struct csi2rx_priv *csi2rx)
> +{
> +	int i;
> +
> +	for (i = 0; i < csi2rx->max_streams; i++)
> +		writel(0, csi2rx->base + CSI2RX_STREAM_CTRL_REG(i));
> +
> +	return 0;
> +}
> +

Here, it is entirely possible that the "dma/buffer" engine which will
make use of this receiver creates separates video nodes for each streams.
In which case, you could theoretically have multiple user space capture
on-going.
But the "start" and "stop" method above would disrupt any of the other
stream. Unless you start and stop all 4 capture streams in lock step.

Eventually, the sub device might be a port aggregator which has up to
4 sensors on the source pad and feed each camera traffic on its own
Virtual Channel.

I know there isn't support in the framework for this currently but it
is something to think about.

Regards,
Benoit

> +static int csi2rx_s_stream(struct v4l2_subdev *sd, int enable)
> +{
> +	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(sd);
> +
> +	v4l2_subdev_call(csi2rx->sensor_subdev, video, s_stream,
> +			 enable);
> +
> +	if (enable)
> +		csi2rx_start(csi2rx);
> +	else
> +		csi2rx_stop(csi2rx);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_video_ops csi2rx_video_ops = {
> +	.s_stream	= csi2rx_s_stream,
> +};
> +
> +static struct v4l2_subdev_ops csi2rx_subdev_ops = {
> +	.video		= &csi2rx_video_ops,
> +};
> +
> +static int csi2rx_async_bound(struct v4l2_async_notifier *notifier,
> +			      struct v4l2_subdev *s_subdev,
> +			      struct v4l2_async_subdev *asd)
> +{
> +	struct v4l2_subdev *subdev = subnotifier_to_v4l2_subdev(notifier);
> +	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
> +
> +	csi2rx->sensor_pad = media_entity_get_fwnode_pad(&s_subdev->entity,
> +							 &csi2rx->sensor_node->fwnode,
> +							 MEDIA_PAD_FL_SOURCE);
> +	if (csi2rx->sensor_pad < 0) {
> +		dev_err(csi2rx->dev, "Couldn't find output pad for subdev %s\n",
> +			s_subdev->name);
> +		return csi2rx->sensor_pad;
> +	}
> +
> +	csi2rx->sensor_subdev = s_subdev;
> +
> +	dev_dbg(csi2rx->dev, "Bound %s pad: %d\n", s_subdev->name,
> +		csi2rx->sensor_pad);
> +
> +	return 0;
> +}
> +
> +static int csi2rx_async_complete(struct v4l2_async_notifier *notifier)
> +{
> +	struct v4l2_subdev *subdev = subnotifier_to_v4l2_subdev(notifier);
> +	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
> +
> +	return media_create_pad_link(&csi2rx->sensor_subdev->entity,
> +				     csi2rx->sensor_pad,
> +				     &csi2rx->subdev.entity, 0,
> +				     MEDIA_LNK_FL_ENABLED |
> +				     MEDIA_LNK_FL_IMMUTABLE);
> +}
> +
> +static void csi2rx_async_unbind(struct v4l2_async_notifier *notifier,
> +				struct v4l2_subdev *s_subdev,
> +				struct v4l2_async_subdev *asd)
> +{
> +	struct v4l2_subdev *subdev = subnotifier_to_v4l2_subdev(notifier);
> +	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
> +
> +	dev_dbg(csi2rx->dev, "Unbound %s pad: %d\n", s_subdev->name,
> +		csi2rx->sensor_pad);
> +
> +	csi2rx->sensor_subdev = NULL;
> +	csi2rx->sensor_pad = -EINVAL;
> +}
> +
> +static int csi2rx_get_resources(struct csi2rx_priv *csi2rx,
> +				struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	u32 reg;
> +	int i;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	csi2rx->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(csi2rx->base)) {
> +		dev_err(&pdev->dev, "Couldn't map our registers\n");
> +		return PTR_ERR(csi2rx->base);
> +	}
> +
> +	reg = readl(csi2rx->base + CSI2RX_DEVICE_CFG_REG);
> +	csi2rx->max_lanes = (reg & 7) + 1;
> +	csi2rx->max_streams = ((reg >> 4) & 7);
> +	csi2rx->cdns_dphy = reg & BIT(3);
> +
> +	csi2rx->sys_clk = devm_clk_get(&pdev->dev, "sys_clk");
> +	if (IS_ERR(csi2rx->sys_clk)) {
> +		dev_err(&pdev->dev, "Couldn't get sys clock\n");
> +		return PTR_ERR(csi2rx->sys_clk);
> +	}
> +
> +	csi2rx->p_clk = devm_clk_get(&pdev->dev, "p_clk");
> +	if (IS_ERR(csi2rx->p_clk)) {
> +		dev_err(&pdev->dev, "Couldn't get P clock\n");
> +		return PTR_ERR(csi2rx->p_clk);
> +	}
> +
> +	csi2rx->p_free_clk = devm_clk_get(&pdev->dev, "p_free_clk");
> +	if (IS_ERR(csi2rx->p_free_clk)) {
> +		dev_err(&pdev->dev, "Couldn't get free running P clock\n");
> +		return PTR_ERR(csi2rx->p_free_clk);
> +	}
> +
> +	for (i = 0; i < csi2rx->max_streams; i++) {
> +		char clk_name[16];
> +
> +		snprintf(clk_name, sizeof(clk_name), "pixel_if%u_clk", i);
> +		csi2rx->pixel_clk[i] = devm_clk_get(&pdev->dev, clk_name);
> +		if (IS_ERR(csi2rx->pixel_clk[i])) {
> +			dev_err(&pdev->dev, "Couldn't get clock %s\n", clk_name);
> +			return PTR_ERR(csi2rx->pixel_clk[i]);
> +		}
> +	}
> +
> +	if (csi2rx->cdns_dphy) {
> +		csi2rx->dphy_rx_clk = devm_clk_get(&pdev->dev, "dphy_rx_clk");
> +		if (IS_ERR(csi2rx->dphy_rx_clk)) {
> +			dev_err(&pdev->dev, "Couldn't get D-PHY RX clock\n");
> +			return PTR_ERR(csi2rx->dphy_rx_clk);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int csi2rx_parse_dt(struct csi2rx_priv *csi2rx)
> +{
> +	struct v4l2_fwnode_endpoint v4l2_ep;
> +	struct v4l2_async_subdev **subdevs;
> +	struct device_node *ep, *remote;
> +	int ret = 0;
> +
> +	ep = of_graph_get_endpoint_by_regs(csi2rx->dev->of_node, 0, 0);
> +	if (!ep)
> +		return -EINVAL;
> +
> +	ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep), &v4l2_ep);
> +	if (ret) {
> +		dev_err(csi2rx->dev, "Could not parse v4l2 endpoint\n");
> +		goto out;
> +	}
> +
> +	if (v4l2_ep.bus_type != V4L2_MBUS_CSI2) {
> +		dev_err(csi2rx->dev, "Unsupported media bus type: 0x%x\n",
> +			v4l2_ep.bus_type);
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	csi2rx->lanes = v4l2_ep.bus.mipi_csi2.num_data_lanes;
> +	if (csi2rx->lanes > csi2rx->max_lanes) {
> +		dev_err(csi2rx->dev, "Unsupported number of data-lanes: %d\n",
> +			csi2rx->lanes);
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	remote = of_graph_get_remote_port_parent(ep);
> +	if (!remote) {
> +		dev_err(csi2rx->dev, "No device found for endpoint %pOF\n", ep);
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	dev_dbg(csi2rx->dev, "Found remote device %pOF\n", remote);
> +
> +	csi2rx->sensor_node = remote;
> +	csi2rx->asd.match.fwnode.fwnode = &remote->fwnode;
> +	csi2rx->asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
> +
> +	subdevs = devm_kzalloc(csi2rx->dev, sizeof(*subdevs), GFP_KERNEL);
> +	if (subdevs == NULL)
> +		return -ENOMEM;
> +	subdevs[0] = &csi2rx->asd;
> +
> +	ret = v4l2_async_subdev_notifier_register(&csi2rx->subdev, 1, subdevs,
> +						  csi2rx_async_bound,
> +						  csi2rx_async_complete,
> +						  csi2rx_async_unbind);
> +	if (ret < 0) {
> +		dev_err(csi2rx->dev, "Failed to register our notifier\n");
> +		return ret;
> +	}
> +
> +out:
> +	of_node_put(ep);
> +	return ret;
> +}
> +
> +static int csi2rx_probe(struct platform_device *pdev)
> +{
> +	struct csi2rx_priv *csi2rx;
> +	int i, ret;
> +
> +	csi2rx = devm_kzalloc(&pdev->dev, sizeof(*csi2rx), GFP_KERNEL);
> +	if (!csi2rx)
> +		return -ENOMEM;
> +	platform_set_drvdata(pdev, csi2rx);
> +	csi2rx->dev = &pdev->dev;
> +
> +	ret = csi2rx_get_resources(csi2rx, pdev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to get our resources\n");
> +		return ret;
> +	}
> +
> +	ret = csi2rx_parse_dt(csi2rx);
> +	if (ret)
> +		return ret;
> +
> +	csi2rx->subdev.owner = THIS_MODULE;
> +	csi2rx->subdev.dev = &pdev->dev;
> +	v4l2_subdev_init(&csi2rx->subdev, &csi2rx_subdev_ops);
> +	v4l2_set_subdevdata(&csi2rx->subdev, &pdev->dev);
> +	snprintf(csi2rx->subdev.name, V4L2_SUBDEV_NAME_SIZE, "%s.%s",
> +		 KBUILD_MODNAME, dev_name(&pdev->dev));
> +
> +	/* Create our media pads */
> +	csi2rx->subdev.entity.function = MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER;
> +	csi2rx->pads[CSI2RX_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
> +	for (i = CSI2RX_PAD_SOURCE_VC0; i < CSI2RX_PAD_MAX; i++)
> +		csi2rx->pads[i].flags = MEDIA_PAD_FL_SOURCE;
> +
> +	ret = media_entity_pads_init(&csi2rx->subdev.entity, CSI2RX_PAD_MAX,
> +				     csi2rx->pads);
> +	if (ret)
> +		return ret;
> +
> +	ret = v4l2_async_register_subdev(&csi2rx->subdev);
> +	if (ret < 0)
> +		return ret;
> +
> +	dev_info(&pdev->dev,
> +		 "Probed CSI2RX with %d/%d lanes, %d streams, %s D-PHY\n",
> +		 csi2rx->lanes, csi2rx->max_lanes, csi2rx->max_streams,
> +		 csi2rx->cdns_dphy ? "Cadence" : "no");
> +
> +	return 0;
> +}
> +
> +static int csi2rx_remove(struct platform_device *pdev)
> +{
> +	struct csi2rx_priv *csi2rx = platform_get_drvdata(pdev);
> +
> +	v4l2_async_unregister_subdev(&csi2rx->subdev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id csi2rx_of_table[] = {
> +	{ .compatible = "cdns,csi2rx" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, csi2rx_of_table);
> +
> +static struct platform_driver csi2rx_driver = {
> +	.probe	= csi2rx_probe,
> +	.remove	= csi2rx_remove,
> +
> +	.driver	= {
> +		.name		= "cdns-csi2rx",
> +		.of_match_table	= csi2rx_of_table,
> +	},
> +};
> +module_platform_driver(csi2rx_driver);
> -- 
> 2.13.3
> 
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