diff mbox

[v4,2/2] v4l: cadence: Add Cadence MIPI-CSI2 RX driver

Message ID 20170922100823.18184-3-maxime.ripard@free-electrons.com (mailing list archive)
State New, archived
Headers show

Commit Message

Maxime Ripard Sept. 22, 2017, 10:08 a.m. UTC 
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@free-electrons.com>
---
 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 | 486 +++++++++++++++++++++++++++
 5 files changed, 502 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

Comments

Benoit Parrot Sept. 29, 2017, 5:27 p.m. UTC | #1 
Maxime Ripard <maxime.ripard@free-electrons.com> wrote on Fri [2017-Sep-22 12:08:23 +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@free-electrons.com>
> ---
>  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 | 486 +++++++++++++++++++++++++++
>  5 files changed, 502 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
> 

<snip>

> +static int csi2rx_get_resources(struct csi2rx_priv *csi2rx,
> +				struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	unsigned char i;
> +	u32 reg;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	csi2rx->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(csi2rx->base))
> +		return PTR_ERR(csi2rx->base);
> +
> +	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->dphy = devm_phy_optional_get(&pdev->dev, "dphy");
> +	if (IS_ERR(csi2rx->dphy)) {
> +		dev_err(&pdev->dev, "Couldn't get external D-PHY\n");
> +		return PTR_ERR(csi2rx->dphy);
> +	}
> +
> +	/*
> +	 * FIXME: Once we'll have external D-PHY support, the check
> +	 * will need to be removed.
> +	 */
> +	if (csi2rx->dphy) {
> +		dev_err(&pdev->dev, "External D-PHY not supported yet\n");
> +		return -EINVAL;
> +	}

I understand that in your current environment you do not have a
DPHY. But I am wondering in a real setup where you will have either
an internal or an external DPHY, how are they going to interact with
this driver or vice-versa?

> +
> +	clk_prepare_enable(csi2rx->p_clk);
> +	reg = readl(csi2rx->base + CSI2RX_DEVICE_CFG_REG);
> +	clk_disable_unprepare(csi2rx->p_clk);
> +
> +	csi2rx->max_lanes = (reg & 7);
> +	if (csi2rx->max_lanes > CSI2RX_LANES_MAX) {
> +		dev_err(&pdev->dev, "Invalid number of lanes: %u\n",
> +			csi2rx->max_lanes);
> +		return -EINVAL;
> +	}
> +
> +	csi2rx->max_streams = ((reg >> 4) & 7);
> +	if (csi2rx->max_streams > CSI2RX_STREAMS_MAX) {
> +		dev_err(&pdev->dev, "Invalid number of streams: %u\n",
> +			csi2rx->max_streams);
> +		return -EINVAL;
> +	}
> +
> +	csi2rx->has_internal_dphy = (reg & BIT(3)) ? true : false;
> +
> +	/*
> +	 * FIXME: Once we'll have internal D-PHY support, the check
> +	 * will need to be removed.
> +	 */
> +	if (csi2rx->has_internal_dphy) {
> +		dev_err(&pdev->dev, "Internal D-PHY not supported yet\n");
> +		return -EINVAL;
> +	}
> +
> +	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]);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int csi2rx_parse_dt(struct csi2rx_priv *csi2rx)
> +{
> +	struct v4l2_fwnode_endpoint v4l2_ep;
> +	struct device_node *ep, *remote;

*remote is now unused.

Regards,
Benoit

<snip>
Maxime Ripard Oct. 11, 2017, 9:24 a.m. UTC | #2 
Hi Benoit,

On Fri, Sep 29, 2017 at 05:27:09PM +0000, Benoit Parrot wrote:
> > +static int csi2rx_get_resources(struct csi2rx_priv *csi2rx,
> > +				struct platform_device *pdev)
> > +{
> > +	struct resource *res;
> > +	unsigned char i;
> > +	u32 reg;
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	csi2rx->base = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(csi2rx->base))
> > +		return PTR_ERR(csi2rx->base);
> > +
> > +	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->dphy = devm_phy_optional_get(&pdev->dev, "dphy");
> > +	if (IS_ERR(csi2rx->dphy)) {
> > +		dev_err(&pdev->dev, "Couldn't get external D-PHY\n");
> > +		return PTR_ERR(csi2rx->dphy);
> > +	}
> > +
> > +	/*
> > +	 * FIXME: Once we'll have external D-PHY support, the check
> > +	 * will need to be removed.
> > +	 */
> > +	if (csi2rx->dphy) {
> > +		dev_err(&pdev->dev, "External D-PHY not supported yet\n");
> > +		return -EINVAL;
> > +	}
> 
> I understand that in your current environment you do not have a
> DPHY. But I am wondering in a real setup where you will have either
> an internal or an external DPHY, how are they going to interact with
> this driver or vice-versa?

It's difficult to give an answer with so little details. How would you
choose between those two PHYs? Is there a mux, or should we just power
one of the two? If that's the case, is there any use case were we
might want to power both? If not, which one should we favor, in which
situations?

I guess all those questions actually depend on the way the integration
has been done, and we're not quite there yet. I guess we could do
either a platform specific structure or a glue, depending on the
complexity. The platform specific compatible will allow us to do that
as we see fit anyway.

> > +
> > +	clk_prepare_enable(csi2rx->p_clk);
> > +	reg = readl(csi2rx->base + CSI2RX_DEVICE_CFG_REG);
> > +	clk_disable_unprepare(csi2rx->p_clk);
> > +
> > +	csi2rx->max_lanes = (reg & 7);
> > +	if (csi2rx->max_lanes > CSI2RX_LANES_MAX) {
> > +		dev_err(&pdev->dev, "Invalid number of lanes: %u\n",
> > +			csi2rx->max_lanes);
> > +		return -EINVAL;
> > +	}
> > +
> > +	csi2rx->max_streams = ((reg >> 4) & 7);
> > +	if (csi2rx->max_streams > CSI2RX_STREAMS_MAX) {
> > +		dev_err(&pdev->dev, "Invalid number of streams: %u\n",
> > +			csi2rx->max_streams);
> > +		return -EINVAL;
> > +	}
> > +
> > +	csi2rx->has_internal_dphy = (reg & BIT(3)) ? true : false;
> > +
> > +	/*
> > +	 * FIXME: Once we'll have internal D-PHY support, the check
> > +	 * will need to be removed.
> > +	 */
> > +	if (csi2rx->has_internal_dphy) {
> > +		dev_err(&pdev->dev, "Internal D-PHY not supported yet\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	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]);
> > +		}
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int csi2rx_parse_dt(struct csi2rx_priv *csi2rx)
> > +{
> > +	struct v4l2_fwnode_endpoint v4l2_ep;
> > +	struct device_node *ep, *remote;
> 
> *remote is now unused.

It's fixed, thanks!
Maxime
Benoit Parrot Oct. 11, 2017, 1:22 p.m. UTC | #3 
Hi Maxime,

Maxime Ripard <maxime.ripard@free-electrons.com> wrote on Wed [2017-Oct-11 11:24:09 +0200]:
> Hi Benoit,
> 
> On Fri, Sep 29, 2017 at 05:27:09PM +0000, Benoit Parrot wrote:
> > > +static int csi2rx_get_resources(struct csi2rx_priv *csi2rx,
> > > +				struct platform_device *pdev)
> > > +{
> > > +	struct resource *res;
> > > +	unsigned char i;
> > > +	u32 reg;
> > > +
> > > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > +	csi2rx->base = devm_ioremap_resource(&pdev->dev, res);
> > > +	if (IS_ERR(csi2rx->base))
> > > +		return PTR_ERR(csi2rx->base);
> > > +
> > > +	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->dphy = devm_phy_optional_get(&pdev->dev, "dphy");
> > > +	if (IS_ERR(csi2rx->dphy)) {
> > > +		dev_err(&pdev->dev, "Couldn't get external D-PHY\n");
> > > +		return PTR_ERR(csi2rx->dphy);
> > > +	}
> > > +
> > > +	/*
> > > +	 * FIXME: Once we'll have external D-PHY support, the check
> > > +	 * will need to be removed.
> > > +	 */
> > > +	if (csi2rx->dphy) {
> > > +		dev_err(&pdev->dev, "External D-PHY not supported yet\n");
> > > +		return -EINVAL;
> > > +	}
> > 
> > I understand that in your current environment you do not have a
> > DPHY. But I am wondering in a real setup where you will have either
> > an internal or an external DPHY, how are they going to interact with
> > this driver or vice-versa?
> 
> It's difficult to give an answer with so little details. How would you
> choose between those two PHYs? Is there a mux, or should we just power
> one of the two? If that's the case, is there any use case were we
> might want to power both? If not, which one should we favor, in which
> situations?

Oops, I guess I should clarify, in this case I did not mean we would
have both an internal and an external DPHY. I just meant one or the other.
Basically just want to see how you would actually handle a DPHY here whether
it's internal or external?

For instance, using direct register access from within this driver or make
use of an separate phy driver...

> 
> I guess all those questions actually depend on the way the integration
> has been done, and we're not quite there yet. I guess we could do
> either a platform specific structure or a glue, depending on the
> complexity. The platform specific compatible will allow us to do that
> as we see fit anyway.
> 

Regards,
Benoit
Maxime Ripard Oct. 13, 2017, 11:48 a.m. UTC | #4 
Hi Benoit,

On Wed, Oct 11, 2017 at 01:22:59PM +0000, Benoit Parrot wrote:
> Maxime Ripard <maxime.ripard@free-electrons.com> wrote on Wed [2017-Oct-11 11:24:09 +0200]:
> > On Fri, Sep 29, 2017 at 05:27:09PM +0000, Benoit Parrot wrote:
> > > > +static int csi2rx_get_resources(struct csi2rx_priv *csi2rx,
> > > > +				struct platform_device *pdev)
> > > > +{
> > > > +	struct resource *res;
> > > > +	unsigned char i;
> > > > +	u32 reg;
> > > > +
> > > > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > > +	csi2rx->base = devm_ioremap_resource(&pdev->dev, res);
> > > > +	if (IS_ERR(csi2rx->base))
> > > > +		return PTR_ERR(csi2rx->base);
> > > > +
> > > > +	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->dphy = devm_phy_optional_get(&pdev->dev, "dphy");
> > > > +	if (IS_ERR(csi2rx->dphy)) {
> > > > +		dev_err(&pdev->dev, "Couldn't get external D-PHY\n");
> > > > +		return PTR_ERR(csi2rx->dphy);
> > > > +	}
> > > > +
> > > > +	/*
> > > > +	 * FIXME: Once we'll have external D-PHY support, the check
> > > > +	 * will need to be removed.
> > > > +	 */
> > > > +	if (csi2rx->dphy) {
> > > > +		dev_err(&pdev->dev, "External D-PHY not supported yet\n");
> > > > +		return -EINVAL;
> > > > +	}
> > > 
> > > I understand that in your current environment you do not have a
> > > DPHY. But I am wondering in a real setup where you will have either
> > > an internal or an external DPHY, how are they going to interact with
> > > this driver or vice-versa?
> > 
> > It's difficult to give an answer with so little details. How would you
> > choose between those two PHYs? Is there a mux, or should we just power
> > one of the two? If that's the case, is there any use case were we
> > might want to power both? If not, which one should we favor, in which
> > situations?
> 
> Oops, I guess I should clarify, in this case I did not mean we would
> have both an internal and an external DPHY. I just meant one or the other.

Ok, my bad :)

> Basically just want to see how you would actually handle a DPHY here
> whether it's internal or external?
> 
> For instance, using direct register access from within this driver
> or make use of an separate phy driver...

So internal would be easy, the only internal D-PHY that is supposed to
be integrated is Cadence's, and its registers would be located in the
same memory region, so that driver would handle it.

In the external case, the ideal solution would be to extend the phy
framework to deal with more phy types. CSI would be a good candidate,
but we also have that issue with the DSI patches Boris has been
sending, and other phy types like USB.

The idea would be to extend it (or subclass it) to allow to pass more
configuration data that would allow to implement a D-PHY driver of its
own. That's the long term goal obviously, and we haven't started
working on that. So we might have to settle for in-drivers quirks
short term.

Maxime
diff mbox

Patch

diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
index 7e7cc49b8674..adfced50504c 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 c1ef946bf032..44d39b7c7bf7 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..0a35ad0b697f
--- /dev/null
+++ b/drivers/media/platform/cadence/cdns-csi2rx.c
@@ -0,0 +1,486 @@ 
+/*
+ * 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/atomic.h>
+#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/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/slab.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_STATIC_CFG_DLANE_MAP(llane, plane)	((plane) << (16 + (llane) * 4))
+#define CSI2RX_STATIC_CFG_LANES_MASK			GENMASK(11, 8)
+
+#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_LANES_MAX	4
+#define CSI2RX_STREAMS_MAX	4
+
+enum csi2rx_pads {
+	CSI2RX_PAD_SINK,
+	CSI2RX_PAD_SOURCE_STREAM0,
+	CSI2RX_PAD_SOURCE_STREAM1,
+	CSI2RX_PAD_SOURCE_STREAM2,
+	CSI2RX_PAD_SOURCE_STREAM3,
+	CSI2RX_PAD_MAX,
+};
+
+struct csi2rx_priv {
+	struct device			*dev;
+	atomic_t			count;
+
+	void __iomem			*base;
+	struct clk			*sys_clk;
+	struct clk			*p_clk;
+	struct clk			*pixel_clk[CSI2RX_STREAMS_MAX];
+	struct phy			*dphy;
+
+	u8				lanes[CSI2RX_LANES_MAX];
+	u8				num_lanes;
+	u8				max_lanes;
+	u8				max_streams;
+	bool				has_internal_dphy;
+
+	struct v4l2_subdev		subdev;
+	struct v4l2_async_notifier	notifier;
+	struct media_pad		pads[CSI2RX_PAD_MAX];
+
+	/* Remote source */
+	struct v4l2_async_subdev	asd;
+	struct v4l2_subdev		*source_subdev;
+	int				source_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);
+
+	usleep_range(10, 20);
+
+	writel(0, csi2rx->base + CSI2RX_SOFT_RESET_REG);
+}
+
+static int csi2rx_start(struct csi2rx_priv *csi2rx)
+{
+	unsigned int i;
+	u32 reg;
+	int ret;
+
+	/*
+	 * We're not the first users, there's no need to enable the
+	 * whole controller.
+	 */
+	if (atomic_inc_return(&csi2rx->count) > 1)
+		return 0;
+
+	clk_prepare_enable(csi2rx->p_clk);
+
+	csi2rx_reset(csi2rx);
+
+	reg = csi2rx->num_lanes << 8;
+	for (i = 0; i < csi2rx->num_lanes; i++)
+		reg |= CSI2RX_STATIC_CFG_DLANE_MAP(i, csi2rx->lanes[i]);
+
+	writel(reg, csi2rx->base + CSI2RX_STATIC_CFG_REG);
+
+	ret = v4l2_subdev_call(csi2rx->source_subdev, video, s_stream, true);
+	if (ret)
+		return ret;
+
+	/*
+	 * 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.
+	 *
+	 * We also cannot enable and disable independant streams here,
+	 * hence the reference counting.
+	 */
+	for (i = 0; i < csi2rx->max_streams; i++) {
+		clk_prepare_enable(csi2rx->pixel_clk[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));
+	}
+
+	clk_prepare_enable(csi2rx->sys_clk);
+
+	clk_disable_unprepare(csi2rx->p_clk);
+
+	return 0;
+}
+
+static int csi2rx_stop(struct csi2rx_priv *csi2rx)
+{
+	unsigned int i;
+
+	/*
+	 * Let the last user turn off the lights
+	 */
+	if (!atomic_dec_and_test(&csi2rx->count))
+		return 0;
+
+	clk_prepare_enable(csi2rx->p_clk);
+
+	for (i = 0; i < csi2rx->max_streams; i++) {
+		writel(0, csi2rx->base + CSI2RX_STREAM_CTRL_REG(i));
+
+		clk_disable_unprepare(csi2rx->pixel_clk[i]);
+	}
+
+	clk_disable_unprepare(csi2rx->p_clk);
+
+	return v4l2_subdev_call(csi2rx->source_subdev, video, s_stream, false);
+}
+
+static int csi2rx_s_stream(struct v4l2_subdev *sd, int enable)
+{
+	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(sd);
+	int ret;
+
+	if (enable)
+		ret = csi2rx_start(csi2rx);
+	else
+		ret = csi2rx_stop(csi2rx);
+
+	return ret;
+}
+
+static const struct v4l2_subdev_video_ops csi2rx_video_ops = {
+	.s_stream	= csi2rx_s_stream,
+};
+
+static const 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 = notifier->sd;
+	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
+
+	csi2rx->source_pad = media_entity_get_fwnode_pad(&s_subdev->entity,
+							 s_subdev->fwnode,
+							 MEDIA_PAD_FL_SOURCE);
+	if (csi2rx->source_pad < 0) {
+		dev_err(csi2rx->dev, "Couldn't find output pad for subdev %s\n",
+			s_subdev->name);
+		return csi2rx->source_pad;
+	}
+
+	csi2rx->source_subdev = s_subdev;
+
+	dev_dbg(csi2rx->dev, "Bound %s pad: %d\n", s_subdev->name,
+		csi2rx->source_pad);
+
+	return 0;
+}
+
+static int csi2rx_async_complete(struct v4l2_async_notifier *notifier)
+{
+	struct v4l2_subdev *subdev = notifier->sd;
+	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
+
+	return media_create_pad_link(&csi2rx->source_subdev->entity,
+				     csi2rx->source_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 = notifier->sd;
+	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
+
+	dev_dbg(csi2rx->dev, "Unbound %s pad: %d\n", s_subdev->name,
+		csi2rx->source_pad);
+
+	csi2rx->source_subdev = NULL;
+	csi2rx->source_pad = -EINVAL;
+}
+
+static const struct v4l2_async_notifier_operations csi2rx_notifier_ops = {
+	.bound		= csi2rx_async_bound,
+	.complete	= csi2rx_async_complete,
+	.unbind		= csi2rx_async_unbind,
+};
+
+static int csi2rx_get_resources(struct csi2rx_priv *csi2rx,
+				struct platform_device *pdev)
+{
+	struct resource *res;
+	unsigned char i;
+	u32 reg;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	csi2rx->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(csi2rx->base))
+		return PTR_ERR(csi2rx->base);
+
+	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->dphy = devm_phy_optional_get(&pdev->dev, "dphy");
+	if (IS_ERR(csi2rx->dphy)) {
+		dev_err(&pdev->dev, "Couldn't get external D-PHY\n");
+		return PTR_ERR(csi2rx->dphy);
+	}
+
+	/*
+	 * FIXME: Once we'll have external D-PHY support, the check
+	 * will need to be removed.
+	 */
+	if (csi2rx->dphy) {
+		dev_err(&pdev->dev, "External D-PHY not supported yet\n");
+		return -EINVAL;
+	}
+
+	clk_prepare_enable(csi2rx->p_clk);
+	reg = readl(csi2rx->base + CSI2RX_DEVICE_CFG_REG);
+	clk_disable_unprepare(csi2rx->p_clk);
+
+	csi2rx->max_lanes = (reg & 7);
+	if (csi2rx->max_lanes > CSI2RX_LANES_MAX) {
+		dev_err(&pdev->dev, "Invalid number of lanes: %u\n",
+			csi2rx->max_lanes);
+		return -EINVAL;
+	}
+
+	csi2rx->max_streams = ((reg >> 4) & 7);
+	if (csi2rx->max_streams > CSI2RX_STREAMS_MAX) {
+		dev_err(&pdev->dev, "Invalid number of streams: %u\n",
+			csi2rx->max_streams);
+		return -EINVAL;
+	}
+
+	csi2rx->has_internal_dphy = (reg & BIT(3)) ? true : false;
+
+	/*
+	 * FIXME: Once we'll have internal D-PHY support, the check
+	 * will need to be removed.
+	 */
+	if (csi2rx->has_internal_dphy) {
+		dev_err(&pdev->dev, "Internal D-PHY not supported yet\n");
+		return -EINVAL;
+	}
+
+	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]);
+		}
+	}
+
+	return 0;
+}
+
+static int csi2rx_parse_dt(struct csi2rx_priv *csi2rx)
+{
+	struct v4l2_fwnode_endpoint v4l2_ep;
+	struct device_node *ep, *remote;
+	int ret;
+
+	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;
+	}
+
+	memcpy(csi2rx->lanes, v4l2_ep.bus.mipi_csi2.data_lanes,
+	       sizeof(csi2rx->lanes));
+	csi2rx->num_lanes = v4l2_ep.bus.mipi_csi2.num_data_lanes;
+	if (csi2rx->num_lanes > csi2rx->max_lanes) {
+		dev_err(csi2rx->dev, "Unsupported number of data-lanes: %d\n",
+			csi2rx->num_lanes);
+		ret = -EINVAL;
+		goto out;
+	}
+
+out:
+	of_node_put(ep);
+	return ret;
+}
+
+static int csi2rx_probe(struct platform_device *pdev)
+{
+	struct csi2rx_priv *csi2rx;
+	unsigned int i;
+	int ret;
+
+	/*
+	 * Since the v4l2_subdev structure is embedded in our
+	 * csi2rx_priv structure, and that the structure is exposed to
+	 * the user-space, we cannot just use the devm_variant
+	 * here. Indeed, that would lead to a use-after-free in a
+	 * open() - unbind - close() pattern.
+	 */
+	csi2rx = kzalloc(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)
+		goto err_free_priv;
+
+	ret = csi2rx_parse_dt(csi2rx);
+	if (ret)
+		goto err_free_priv;
+
+	csi2rx->notifier.ops = &csi2rx_notifier_ops;
+	csi2rx->notifier.max_subdevs = 1;
+	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_STREAM0; i < CSI2RX_PAD_MAX; i++)
+		csi2rx->pads[i].flags = MEDIA_PAD_FL_SOURCE;
+
+	ret = v4l2_async_notifier_parse_fwnode_endpoints_by_port(csi2rx->dev,
+								 &csi2rx->notifier,
+								 sizeof(struct v4l2_async_subdev),
+								 0, NULL);
+	if (ret < 0) {
+		dev_err(csi2rx->dev, "Failed to parse our endpoints\n");
+		goto err_free_priv;
+	}
+
+	ret = v4l2_async_subdev_notifier_register(&csi2rx->subdev,
+						  &csi2rx->notifier);
+	if (ret < 0) {
+		dev_err(csi2rx->dev, "Failed to register our notifier\n");
+		goto err_free_priv;
+	}
+
+	ret = media_entity_pads_init(&csi2rx->subdev.entity, CSI2RX_PAD_MAX,
+				     csi2rx->pads);
+	if (ret)
+		goto err_free_priv;
+
+	ret = v4l2_async_register_subdev(&csi2rx->subdev);
+	if (ret < 0)
+		goto err_free_priv;
+
+	dev_info(&pdev->dev,
+		 "Probed CSI2RX with %u/%u lanes, %u streams, %s D-PHY\n",
+		 csi2rx->num_lanes, csi2rx->max_lanes, csi2rx->max_streams,
+		 csi2rx->has_internal_dphy ? "internal" : "no");
+
+	return 0;
+
+err_free_priv:
+	kfree(csi2rx);
+	return ret;
+}
+
+static int csi2rx_remove(struct platform_device *pdev)
+{
+	struct csi2rx_priv *csi2rx = platform_get_drvdata(pdev);
+
+	v4l2_async_unregister_subdev(&csi2rx->subdev);
+	kfree(csi2rx);
+
+	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);