diff mbox series

[v7,3/7] drm: rcar-du: Add support for CMM

Message ID 20191113100556.15616-4-jacopo+renesas@jmondi.org (mailing list archive)
State New
Delegated to: Kieran Bingham
Headers show
Series drm: rcar-du: Add Color Management Module (CMM) | expand

Commit Message

Jacopo Mondi Nov. 13, 2019, 10:05 a.m. UTC 
Add a driver for the R-Car Display Unit Color Correction Module.

In most of Gen3 SoCs, each DU output channel is provided with a CMM unit
to perform image enhancement and color correction.

Add support for CMM through a driver that supports configuration of
the 1-dimensional LUT table. More advanced CMM features will be
implemented on top of this initial one.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>

---
v6 -> v7
- Expand rcar_cmm_setup() function documentation to detail its relationship
  with rcar_cmm_enable() and their call order precedence.

- Kconfig update: Make DRM_RCAR_CMM a tristate option and 'imply' it from the
  RCAR_DU one. This guarantees that if DU is built as a module CMM can only be
  built as a module as well. At the same time, if DU is built-in, CMM can
  be built-in only.
---
 drivers/gpu/drm/rcar-du/Kconfig    |   8 ++
 drivers/gpu/drm/rcar-du/Makefile   |   1 +
 drivers/gpu/drm/rcar-du/rcar_cmm.c | 217 +++++++++++++++++++++++++++++
 drivers/gpu/drm/rcar-du/rcar_cmm.h |  58 ++++++++
 4 files changed, 284 insertions(+)
 create mode 100644 drivers/gpu/drm/rcar-du/rcar_cmm.c
 create mode 100644 drivers/gpu/drm/rcar-du/rcar_cmm.h

--
2.23.0

Comments

Laurent Pinchart Nov. 28, 2019, 1:52 a.m. UTC | #1 
Hi Jacopo,

Thank you for the patch.

On Wed, Nov 13, 2019 at 11:05:52AM +0100, Jacopo Mondi wrote:
> Add a driver for the R-Car Display Unit Color Correction Module.
> 
> In most of Gen3 SoCs, each DU output channel is provided with a CMM unit
> to perform image enhancement and color correction.
> 
> Add support for CMM through a driver that supports configuration of
> the 1-dimensional LUT table. More advanced CMM features will be
> implemented on top of this initial one.
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> 
> ---
> v6 -> v7
> - Expand rcar_cmm_setup() function documentation to detail its relationship
>   with rcar_cmm_enable() and their call order precedence.
> 
> - Kconfig update: Make DRM_RCAR_CMM a tristate option and 'imply' it from the
>   RCAR_DU one. This guarantees that if DU is built as a module CMM can only be
>   built as a module as well. At the same time, if DU is built-in, CMM can
>   be built-in only.
> ---
>  drivers/gpu/drm/rcar-du/Kconfig    |   8 ++
>  drivers/gpu/drm/rcar-du/Makefile   |   1 +
>  drivers/gpu/drm/rcar-du/rcar_cmm.c | 217 +++++++++++++++++++++++++++++
>  drivers/gpu/drm/rcar-du/rcar_cmm.h |  58 ++++++++
>  4 files changed, 284 insertions(+)
>  create mode 100644 drivers/gpu/drm/rcar-du/rcar_cmm.c
>  create mode 100644 drivers/gpu/drm/rcar-du/rcar_cmm.h
> 
> diff --git a/drivers/gpu/drm/rcar-du/Kconfig b/drivers/gpu/drm/rcar-du/Kconfig
> index 1529849e217e..6ed7a4f3c44e 100644
> --- a/drivers/gpu/drm/rcar-du/Kconfig
> +++ b/drivers/gpu/drm/rcar-du/Kconfig
> @@ -5,6 +5,7 @@ config DRM_RCAR_DU
>  	depends on ARM || ARM64
>  	depends on ARCH_RENESAS || COMPILE_TEST
>  	imply DRM_RCAR_LVDS
> +	imply DRM_RCAR_CMM

I'll swap those two lines.

>  	select DRM_KMS_HELPER
>  	select DRM_KMS_CMA_HELPER
>  	select DRM_GEM_CMA_HELPER
> @@ -13,6 +14,13 @@ config DRM_RCAR_DU
>  	  Choose this option if you have an R-Car chipset.
>  	  If M is selected the module will be called rcar-du-drm.
> 
> +config DRM_RCAR_CMM
> +	tristate "R-Car DU Color Management Module (CMM) Support"
> +	depends on DRM && OF
> +	depends on DRM_RCAR_DU

I just wanted to point out that this prevents DRM_RCAR_DU=m and
DRM_RCAR_CMM=y, but I don't think that is a useful use case.

> +	help
> +	  Enable support for R-Car Color Management Module (CMM).
> +
>  config DRM_RCAR_DW_HDMI
>  	tristate "R-Car DU Gen3 HDMI Encoder Support"
>  	depends on DRM && OF
> diff --git a/drivers/gpu/drm/rcar-du/Makefile b/drivers/gpu/drm/rcar-du/Makefile
> index 6c2ed9c46467..4d1187ccc3e5 100644
> --- a/drivers/gpu/drm/rcar-du/Makefile
> +++ b/drivers/gpu/drm/rcar-du/Makefile
> @@ -15,6 +15,7 @@ rcar-du-drm-$(CONFIG_DRM_RCAR_LVDS)	+= rcar_du_of.o \
>  rcar-du-drm-$(CONFIG_DRM_RCAR_VSP)	+= rcar_du_vsp.o
>  rcar-du-drm-$(CONFIG_DRM_RCAR_WRITEBACK) += rcar_du_writeback.o
> 
> +obj-$(CONFIG_DRM_RCAR_CMM)		+= rcar_cmm.o
>  obj-$(CONFIG_DRM_RCAR_DU)		+= rcar-du-drm.o
>  obj-$(CONFIG_DRM_RCAR_DW_HDMI)		+= rcar_dw_hdmi.o
>  obj-$(CONFIG_DRM_RCAR_LVDS)		+= rcar_lvds.o
> diff --git a/drivers/gpu/drm/rcar-du/rcar_cmm.c b/drivers/gpu/drm/rcar-du/rcar_cmm.c
> new file mode 100644
> index 000000000000..c578095b09a5
> --- /dev/null
> +++ b/drivers/gpu/drm/rcar-du/rcar_cmm.c
> @@ -0,0 +1,217 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * rcar_cmm.c -- R-Car Display Unit Color Management Module
> + *
> + * Copyright (C) 2019 Jacopo Mondi <jacopo+renesas@jmondi.org>
> + */
> +
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +
> +#include <drm/drm_color_mgmt.h>
> +
> +#include "rcar_cmm.h"
> +
> +#define CM2_LUT_CTRL		0x0000
> +#define CM2_LUT_CTRL_LUT_EN	BIT(0)
> +#define CM2_LUT_TBL_BASE	0x0600
> +#define CM2_LUT_TBL(__i)	(CM2_LUT_TBL_BASE + (__i) * 4)
> +
> +struct rcar_cmm {
> +	void __iomem *base;
> +
> +	/*
> +	 * @lut:		1D-LUT state
> +	 * @lut.enabled:	1D-LUT enabled flag
> +	 */
> +	struct {
> +		bool enabled;
> +	} lut;
> +};
> +
> +static inline int rcar_cmm_read(struct rcar_cmm *rcmm, u32 reg)
> +{
> +	return ioread32(rcmm->base + reg);
> +}
> +
> +static inline void rcar_cmm_write(struct rcar_cmm *rcmm, u32 reg, u32 data)
> +{
> +	iowrite32(data, rcmm->base + reg);
> +}
> +
> +/*
> + * rcar_cmm_lut_write() - Scale the DRM LUT table entries to hardware precision
> + *			  and write to the CMM registers
> + * @rcmm: Pointer to the CMM device
> + * @drm_lut: Pointer to the DRM LUT table
> + */
> +static void rcar_cmm_lut_write(struct rcar_cmm *rcmm,
> +			       const struct drm_color_lut *drm_lut)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < CM2_LUT_SIZE; ++i) {
> +		u32 entry = drm_color_lut_extract(drm_lut[i].red, 8) << 16
> +			  | drm_color_lut_extract(drm_lut[i].green, 8) << 8
> +			  | drm_color_lut_extract(drm_lut[i].blue, 8);
> +
> +		rcar_cmm_write(rcmm, CM2_LUT_TBL(i), entry);
> +	}
> +}
> +
> +/*
> + * rcar_cmm_setup() - Configure the CMM unit
> + * @pdev: The platform device associated with the CMM instance
> + * @config: The CMM unit configuration
> + *
> + * Configure the CMM unit with the given configuration. Currently enabling,
> + * disabling and programming of the 1-D LUT unit is supported.
> + *
> + * As rcar_cmm_setup() accesses the CMM registers the unit should be powered
> + * and its functional clock enabled. To guarantee this, before any call to
> + * this function is made, the CMM unit has to be enabled by calling
> + * rcar_cmm_enable() first.
> + *
> + * TODO: Add support for LUT double buffer operations to avoid updating the
> + * LUT table entries while a frame is being displayed.
> + */
> +int rcar_cmm_setup(struct platform_device *pdev,
> +		   const struct rcar_cmm_config *config)
> +{
> +	struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
> +
> +	/* Disable LUT if no table is provided. */
> +	if (!config->lut.table) {
> +		if (rcmm->lut.enabled) {
> +			rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
> +			rcmm->lut.enabled = false;
> +		}
> +
> +		return 0;
> +	}
> +
> +	/* Enable LUT and program the new gamma table values. */
> +	if (!rcmm->lut.enabled) {
> +		rcar_cmm_write(rcmm, CM2_LUT_CTRL, CM2_LUT_CTRL_LUT_EN);
> +		rcmm->lut.enabled = true;
> +	}
> +
> +	rcar_cmm_lut_write(rcmm, config->lut.table);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(rcar_cmm_setup);
> +
> +/*
> + * rcar_cmm_enable() - Enable the CMM unit
> + * @pdev: The platform device associated with the CMM instance
> + *
> + * When the output of the corresponding DU channel is routed to the CMM unit,
> + * the unit shall be enabled before the DU channel is started, and remain
> + * enabled until the channel is stopped. The CMM unit shall be disabled with
> + * rcar_cmm_disable().
> + *
> + * Calls to rcar_cmm_enable() and rcar_cmm_disable() are not reference-counted.
> + * It is an error to attempt to enable an already enabled CMM unit, or to
> + * attempt to disable a disabled unit.
> + */
> +int rcar_cmm_enable(struct platform_device *pdev)
> +{
> +	int ret;
> +
> +	ret = pm_runtime_get_sync(&pdev->dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(rcar_cmm_enable);
> +
> +/*
> + * rcar_cmm_disable() - Disable the CMM unit
> + * @pdev: The platform device associated with the CMM instance
> + *
> + * See rcar_cmm_enable() for usage information.
> + *
> + * Disabling the CMM unit disable all the internal processing blocks. The CMM
> + * state shall thus be restored with rcar_cmm_setup() when re-enabling the CMM
> + * unit after the next rcar_cmm_enable() call.
> + */
> +void rcar_cmm_disable(struct platform_device *pdev)
> +{
> +	struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
> +
> +	rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
> +	rcmm->lut.enabled = false;
> +
> +	pm_runtime_put(&pdev->dev);
> +}
> +EXPORT_SYMBOL_GPL(rcar_cmm_disable);
> +
> +/*
> + * rcar_cmm_init() - Initialize the CMM unit
> + * @pdev: The platform device associated with the CMM instance
> + *
> + * Return: 0 on success, -EPROBE_DEFER if the CMM is not available yet,
> + *         -ENODEV if the DRM_RCAR_CMM config option is disabled
> + */
> +int rcar_cmm_init(struct platform_device *pdev)
> +{
> +	struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
> +
> +	if (!rcmm)
> +		return -EPROBE_DEFER;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(rcar_cmm_init);
> +
> +static int rcar_cmm_probe(struct platform_device *pdev)
> +{
> +	struct rcar_cmm *rcmm;
> +
> +	rcmm = devm_kzalloc(&pdev->dev, sizeof(*rcmm), GFP_KERNEL);
> +	if (!rcmm)
> +		return -ENOMEM;
> +	platform_set_drvdata(pdev, rcmm);
> +
> +	rcmm->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(rcmm->base))
> +		return PTR_ERR(rcmm->base);
> +
> +	pm_runtime_enable(&pdev->dev);
> +
> +	return 0;
> +}
> +
> +static int rcar_cmm_remove(struct platform_device *pdev)
> +{
> +	pm_runtime_disable(&pdev->dev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id rcar_cmm_of_table[] = {
> +	{ .compatible = "renesas,rcar-gen3-cmm", },
> +	{ .compatible = "renesas,rcar-gen2-cmm", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, rcar_cmm_of_table);
> +
> +static struct platform_driver rcar_cmm_platform_driver = {
> +	.probe		= rcar_cmm_probe,
> +	.remove		= rcar_cmm_remove,
> +	.driver		= {
> +		.name	= "rcar-cmm",
> +		.of_match_table = rcar_cmm_of_table,
> +	},
> +};
> +
> +module_platform_driver(rcar_cmm_platform_driver);
> +
> +MODULE_AUTHOR("Jacopo Mondi <jacopo+renesas@jmondi.org>");
> +MODULE_DESCRIPTION("Renesas R-Car CMM Driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/gpu/drm/rcar-du/rcar_cmm.h b/drivers/gpu/drm/rcar-du/rcar_cmm.h
> new file mode 100644
> index 000000000000..b5f7ec6db04a
> --- /dev/null
> +++ b/drivers/gpu/drm/rcar-du/rcar_cmm.h
> @@ -0,0 +1,58 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * rcar_cmm.h -- R-Car Display Unit Color Management Module
> + *
> + * Copyright (C) 2019 Jacopo Mondi <jacopo+renesas@jmondi.org>
> + */
> +
> +#ifndef __RCAR_CMM_H__
> +#define __RCAR_CMM_H__
> +
> +#define CM2_LUT_SIZE		256
> +
> +struct drm_color_lut;
> +struct platform_device;
> +
> +/**
> + * struct rcar_cmm_config - CMM configuration
> + *
> + * @lut:	1D-LUT configuration
> + * @lut.table:	1D-LUT table entries. Disable LUT operations when NULL
> + */
> +struct rcar_cmm_config {
> +	struct {
> +		struct drm_color_lut *table;
> +	} lut;
> +};
> +
> +#if IS_ENABLED(CONFIG_DRM_RCAR_CMM)
> +int rcar_cmm_init(struct platform_device *pdev);
> +
> +int rcar_cmm_enable(struct platform_device *pdev);
> +void rcar_cmm_disable(struct platform_device *pdev);
> +
> +int rcar_cmm_setup(struct platform_device *pdev,
> +		   const struct rcar_cmm_config *config);
> +#else
> +static inline int rcar_cmm_init(struct platform_device *pdev)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int rcar_cmm_enable(struct platform_device *pdev)
> +{
> +	return 0;
> +}
> +
> +static inline void rcar_cmm_disable(struct platform_device *pdev)
> +{
> +}
> +
> +static inline int rcar_cmm_setup(struct platform_device *pdev,
> +				 const struct rcar_cmm_config *config)
> +{
> +	return 0;
> +}
> +#endif /* IS_ENABLED(CONFIG_DRM_RCAR_CMM) */
> +
> +#endif /* __RCAR_CMM_H__ */
Geert Uytterhoeven Nov. 28, 2019, 7:56 a.m. UTC | #2 
Hi Jacopo,

On Wed, Nov 13, 2019 at 11:04 AM Jacopo Mondi <jacopo+renesas@jmondi.org> wrote:
> Add a driver for the R-Car Display Unit Color Correction Module.
> In most of Gen3 SoCs, each DU output channel is provided with a CMM unit
> to perform image enhancement and color correction.
>
> Add support for CMM through a driver that supports configuration of
> the 1-dimensional LUT table. More advanced CMM features will be
> implemented on top of this initial one.
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>

> --- a/drivers/gpu/drm/rcar-du/Kconfig
> +++ b/drivers/gpu/drm/rcar-du/Kconfig
> @@ -5,6 +5,7 @@ config DRM_RCAR_DU
>         depends on ARM || ARM64
>         depends on ARCH_RENESAS || COMPILE_TEST
>         imply DRM_RCAR_LVDS
> +       imply DRM_RCAR_CMM
>         select DRM_KMS_HELPER
>         select DRM_KMS_CMA_HELPER
>         select DRM_GEM_CMA_HELPER
> @@ -13,6 +14,13 @@ config DRM_RCAR_DU
>           Choose this option if you have an R-Car chipset.
>           If M is selected the module will be called rcar-du-drm.
>
> +config DRM_RCAR_CMM
> +       tristate "R-Car DU Color Management Module (CMM) Support"
> +       depends on DRM && OF
> +       depends on DRM_RCAR_DU

DRM_RCAR_DU already depends on DRM && OF, so the line above
can be removed.

Gr{oetje,eeting}s,

                        Geert
Laurent Pinchart Nov. 28, 2019, 8:09 a.m. UTC | #3 
Hi Geert,

On Thu, Nov 28, 2019 at 08:56:14AM +0100, Geert Uytterhoeven wrote:
> On Wed, Nov 13, 2019 at 11:04 AM Jacopo Mondi <jacopo+renesas@jmondi.org> wrote:
> > Add a driver for the R-Car Display Unit Color Correction Module.
> > In most of Gen3 SoCs, each DU output channel is provided with a CMM unit
> > to perform image enhancement and color correction.
> >
> > Add support for CMM through a driver that supports configuration of
> > the 1-dimensional LUT table. More advanced CMM features will be
> > implemented on top of this initial one.
> >
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> 
> > --- a/drivers/gpu/drm/rcar-du/Kconfig
> > +++ b/drivers/gpu/drm/rcar-du/Kconfig
> > @@ -5,6 +5,7 @@ config DRM_RCAR_DU
> >         depends on ARM || ARM64
> >         depends on ARCH_RENESAS || COMPILE_TEST
> >         imply DRM_RCAR_LVDS
> > +       imply DRM_RCAR_CMM
> >         select DRM_KMS_HELPER
> >         select DRM_KMS_CMA_HELPER
> >         select DRM_GEM_CMA_HELPER
> > @@ -13,6 +14,13 @@ config DRM_RCAR_DU
> >           Choose this option if you have an R-Car chipset.
> >           If M is selected the module will be called rcar-du-drm.
> >
> > +config DRM_RCAR_CMM
> > +       tristate "R-Car DU Color Management Module (CMM) Support"
> > +       depends on DRM && OF
> > +       depends on DRM_RCAR_DU
> 
> DRM_RCAR_DU already depends on DRM && OF, so the line above
> can be removed.

I've sent a pull request already. Can we address this on top ? Or is it
worth a separate patch, should we wait until we have to touch this and
then fix it in a "while at it" fashion ?
Geert Uytterhoeven Nov. 28, 2019, 8:24 a.m. UTC | #4 
Hi Laurent,

On Thu, Nov 28, 2019 at 9:09 AM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> On Thu, Nov 28, 2019 at 08:56:14AM +0100, Geert Uytterhoeven wrote:
> > On Wed, Nov 13, 2019 at 11:04 AM Jacopo Mondi <jacopo+renesas@jmondi.org> wrote:
> > > Add a driver for the R-Car Display Unit Color Correction Module.
> > > In most of Gen3 SoCs, each DU output channel is provided with a CMM unit
> > > to perform image enhancement and color correction.
> > >
> > > Add support for CMM through a driver that supports configuration of
> > > the 1-dimensional LUT table. More advanced CMM features will be
> > > implemented on top of this initial one.
> > >
> > > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> >
> > > --- a/drivers/gpu/drm/rcar-du/Kconfig
> > > +++ b/drivers/gpu/drm/rcar-du/Kconfig
> > > @@ -5,6 +5,7 @@ config DRM_RCAR_DU
> > >         depends on ARM || ARM64
> > >         depends on ARCH_RENESAS || COMPILE_TEST
> > >         imply DRM_RCAR_LVDS
> > > +       imply DRM_RCAR_CMM
> > >         select DRM_KMS_HELPER
> > >         select DRM_KMS_CMA_HELPER
> > >         select DRM_GEM_CMA_HELPER
> > > @@ -13,6 +14,13 @@ config DRM_RCAR_DU
> > >           Choose this option if you have an R-Car chipset.
> > >           If M is selected the module will be called rcar-du-drm.
> > >
> > > +config DRM_RCAR_CMM
> > > +       tristate "R-Car DU Color Management Module (CMM) Support"
> > > +       depends on DRM && OF
> > > +       depends on DRM_RCAR_DU
> >
> > DRM_RCAR_DU already depends on DRM && OF, so the line above
> > can be removed.
>
> I've sent a pull request already. Can we address this on top ? Or is it
> worth a separate patch, should we wait until we have to touch this and
> then fix it in a "while at it" fashion ?

Sure. "while at it" is fine for me.  It's not blocker.

Gr{oetje,eeting}s,

                        Geert
diff mbox series

Patch

diff --git a/drivers/gpu/drm/rcar-du/Kconfig b/drivers/gpu/drm/rcar-du/Kconfig
index 1529849e217e..6ed7a4f3c44e 100644
--- a/drivers/gpu/drm/rcar-du/Kconfig
+++ b/drivers/gpu/drm/rcar-du/Kconfig
@@ -5,6 +5,7 @@  config DRM_RCAR_DU
 	depends on ARM || ARM64
 	depends on ARCH_RENESAS || COMPILE_TEST
 	imply DRM_RCAR_LVDS
+	imply DRM_RCAR_CMM
 	select DRM_KMS_HELPER
 	select DRM_KMS_CMA_HELPER
 	select DRM_GEM_CMA_HELPER
@@ -13,6 +14,13 @@  config DRM_RCAR_DU
 	  Choose this option if you have an R-Car chipset.
 	  If M is selected the module will be called rcar-du-drm.

+config DRM_RCAR_CMM
+	tristate "R-Car DU Color Management Module (CMM) Support"
+	depends on DRM && OF
+	depends on DRM_RCAR_DU
+	help
+	  Enable support for R-Car Color Management Module (CMM).
+
 config DRM_RCAR_DW_HDMI
 	tristate "R-Car DU Gen3 HDMI Encoder Support"
 	depends on DRM && OF
diff --git a/drivers/gpu/drm/rcar-du/Makefile b/drivers/gpu/drm/rcar-du/Makefile
index 6c2ed9c46467..4d1187ccc3e5 100644
--- a/drivers/gpu/drm/rcar-du/Makefile
+++ b/drivers/gpu/drm/rcar-du/Makefile
@@ -15,6 +15,7 @@  rcar-du-drm-$(CONFIG_DRM_RCAR_LVDS)	+= rcar_du_of.o \
 rcar-du-drm-$(CONFIG_DRM_RCAR_VSP)	+= rcar_du_vsp.o
 rcar-du-drm-$(CONFIG_DRM_RCAR_WRITEBACK) += rcar_du_writeback.o

+obj-$(CONFIG_DRM_RCAR_CMM)		+= rcar_cmm.o
 obj-$(CONFIG_DRM_RCAR_DU)		+= rcar-du-drm.o
 obj-$(CONFIG_DRM_RCAR_DW_HDMI)		+= rcar_dw_hdmi.o
 obj-$(CONFIG_DRM_RCAR_LVDS)		+= rcar_lvds.o
diff --git a/drivers/gpu/drm/rcar-du/rcar_cmm.c b/drivers/gpu/drm/rcar-du/rcar_cmm.c
new file mode 100644
index 000000000000..c578095b09a5
--- /dev/null
+++ b/drivers/gpu/drm/rcar-du/rcar_cmm.c
@@ -0,0 +1,217 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * rcar_cmm.c -- R-Car Display Unit Color Management Module
+ *
+ * Copyright (C) 2019 Jacopo Mondi <jacopo+renesas@jmondi.org>
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#include <drm/drm_color_mgmt.h>
+
+#include "rcar_cmm.h"
+
+#define CM2_LUT_CTRL		0x0000
+#define CM2_LUT_CTRL_LUT_EN	BIT(0)
+#define CM2_LUT_TBL_BASE	0x0600
+#define CM2_LUT_TBL(__i)	(CM2_LUT_TBL_BASE + (__i) * 4)
+
+struct rcar_cmm {
+	void __iomem *base;
+
+	/*
+	 * @lut:		1D-LUT state
+	 * @lut.enabled:	1D-LUT enabled flag
+	 */
+	struct {
+		bool enabled;
+	} lut;
+};
+
+static inline int rcar_cmm_read(struct rcar_cmm *rcmm, u32 reg)
+{
+	return ioread32(rcmm->base + reg);
+}
+
+static inline void rcar_cmm_write(struct rcar_cmm *rcmm, u32 reg, u32 data)
+{
+	iowrite32(data, rcmm->base + reg);
+}
+
+/*
+ * rcar_cmm_lut_write() - Scale the DRM LUT table entries to hardware precision
+ *			  and write to the CMM registers
+ * @rcmm: Pointer to the CMM device
+ * @drm_lut: Pointer to the DRM LUT table
+ */
+static void rcar_cmm_lut_write(struct rcar_cmm *rcmm,
+			       const struct drm_color_lut *drm_lut)
+{
+	unsigned int i;
+
+	for (i = 0; i < CM2_LUT_SIZE; ++i) {
+		u32 entry = drm_color_lut_extract(drm_lut[i].red, 8) << 16
+			  | drm_color_lut_extract(drm_lut[i].green, 8) << 8
+			  | drm_color_lut_extract(drm_lut[i].blue, 8);
+
+		rcar_cmm_write(rcmm, CM2_LUT_TBL(i), entry);
+	}
+}
+
+/*
+ * rcar_cmm_setup() - Configure the CMM unit
+ * @pdev: The platform device associated with the CMM instance
+ * @config: The CMM unit configuration
+ *
+ * Configure the CMM unit with the given configuration. Currently enabling,
+ * disabling and programming of the 1-D LUT unit is supported.
+ *
+ * As rcar_cmm_setup() accesses the CMM registers the unit should be powered
+ * and its functional clock enabled. To guarantee this, before any call to
+ * this function is made, the CMM unit has to be enabled by calling
+ * rcar_cmm_enable() first.
+ *
+ * TODO: Add support for LUT double buffer operations to avoid updating the
+ * LUT table entries while a frame is being displayed.
+ */
+int rcar_cmm_setup(struct platform_device *pdev,
+		   const struct rcar_cmm_config *config)
+{
+	struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
+
+	/* Disable LUT if no table is provided. */
+	if (!config->lut.table) {
+		if (rcmm->lut.enabled) {
+			rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
+			rcmm->lut.enabled = false;
+		}
+
+		return 0;
+	}
+
+	/* Enable LUT and program the new gamma table values. */
+	if (!rcmm->lut.enabled) {
+		rcar_cmm_write(rcmm, CM2_LUT_CTRL, CM2_LUT_CTRL_LUT_EN);
+		rcmm->lut.enabled = true;
+	}
+
+	rcar_cmm_lut_write(rcmm, config->lut.table);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rcar_cmm_setup);
+
+/*
+ * rcar_cmm_enable() - Enable the CMM unit
+ * @pdev: The platform device associated with the CMM instance
+ *
+ * When the output of the corresponding DU channel is routed to the CMM unit,
+ * the unit shall be enabled before the DU channel is started, and remain
+ * enabled until the channel is stopped. The CMM unit shall be disabled with
+ * rcar_cmm_disable().
+ *
+ * Calls to rcar_cmm_enable() and rcar_cmm_disable() are not reference-counted.
+ * It is an error to attempt to enable an already enabled CMM unit, or to
+ * attempt to disable a disabled unit.
+ */
+int rcar_cmm_enable(struct platform_device *pdev)
+{
+	int ret;
+
+	ret = pm_runtime_get_sync(&pdev->dev);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rcar_cmm_enable);
+
+/*
+ * rcar_cmm_disable() - Disable the CMM unit
+ * @pdev: The platform device associated with the CMM instance
+ *
+ * See rcar_cmm_enable() for usage information.
+ *
+ * Disabling the CMM unit disable all the internal processing blocks. The CMM
+ * state shall thus be restored with rcar_cmm_setup() when re-enabling the CMM
+ * unit after the next rcar_cmm_enable() call.
+ */
+void rcar_cmm_disable(struct platform_device *pdev)
+{
+	struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
+
+	rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
+	rcmm->lut.enabled = false;
+
+	pm_runtime_put(&pdev->dev);
+}
+EXPORT_SYMBOL_GPL(rcar_cmm_disable);
+
+/*
+ * rcar_cmm_init() - Initialize the CMM unit
+ * @pdev: The platform device associated with the CMM instance
+ *
+ * Return: 0 on success, -EPROBE_DEFER if the CMM is not available yet,
+ *         -ENODEV if the DRM_RCAR_CMM config option is disabled
+ */
+int rcar_cmm_init(struct platform_device *pdev)
+{
+	struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
+
+	if (!rcmm)
+		return -EPROBE_DEFER;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rcar_cmm_init);
+
+static int rcar_cmm_probe(struct platform_device *pdev)
+{
+	struct rcar_cmm *rcmm;
+
+	rcmm = devm_kzalloc(&pdev->dev, sizeof(*rcmm), GFP_KERNEL);
+	if (!rcmm)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, rcmm);
+
+	rcmm->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rcmm->base))
+		return PTR_ERR(rcmm->base);
+
+	pm_runtime_enable(&pdev->dev);
+
+	return 0;
+}
+
+static int rcar_cmm_remove(struct platform_device *pdev)
+{
+	pm_runtime_disable(&pdev->dev);
+
+	return 0;
+}
+
+static const struct of_device_id rcar_cmm_of_table[] = {
+	{ .compatible = "renesas,rcar-gen3-cmm", },
+	{ .compatible = "renesas,rcar-gen2-cmm", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, rcar_cmm_of_table);
+
+static struct platform_driver rcar_cmm_platform_driver = {
+	.probe		= rcar_cmm_probe,
+	.remove		= rcar_cmm_remove,
+	.driver		= {
+		.name	= "rcar-cmm",
+		.of_match_table = rcar_cmm_of_table,
+	},
+};
+
+module_platform_driver(rcar_cmm_platform_driver);
+
+MODULE_AUTHOR("Jacopo Mondi <jacopo+renesas@jmondi.org>");
+MODULE_DESCRIPTION("Renesas R-Car CMM Driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/gpu/drm/rcar-du/rcar_cmm.h b/drivers/gpu/drm/rcar-du/rcar_cmm.h
new file mode 100644
index 000000000000..b5f7ec6db04a
--- /dev/null
+++ b/drivers/gpu/drm/rcar-du/rcar_cmm.h
@@ -0,0 +1,58 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * rcar_cmm.h -- R-Car Display Unit Color Management Module
+ *
+ * Copyright (C) 2019 Jacopo Mondi <jacopo+renesas@jmondi.org>
+ */
+
+#ifndef __RCAR_CMM_H__
+#define __RCAR_CMM_H__
+
+#define CM2_LUT_SIZE		256
+
+struct drm_color_lut;
+struct platform_device;
+
+/**
+ * struct rcar_cmm_config - CMM configuration
+ *
+ * @lut:	1D-LUT configuration
+ * @lut.table:	1D-LUT table entries. Disable LUT operations when NULL
+ */
+struct rcar_cmm_config {
+	struct {
+		struct drm_color_lut *table;
+	} lut;
+};
+
+#if IS_ENABLED(CONFIG_DRM_RCAR_CMM)
+int rcar_cmm_init(struct platform_device *pdev);
+
+int rcar_cmm_enable(struct platform_device *pdev);
+void rcar_cmm_disable(struct platform_device *pdev);
+
+int rcar_cmm_setup(struct platform_device *pdev,
+		   const struct rcar_cmm_config *config);
+#else
+static inline int rcar_cmm_init(struct platform_device *pdev)
+{
+	return -ENODEV;
+}
+
+static inline int rcar_cmm_enable(struct platform_device *pdev)
+{
+	return 0;
+}
+
+static inline void rcar_cmm_disable(struct platform_device *pdev)
+{
+}
+
+static inline int rcar_cmm_setup(struct platform_device *pdev,
+				 const struct rcar_cmm_config *config)
+{
+	return 0;
+}
+#endif /* IS_ENABLED(CONFIG_DRM_RCAR_CMM) */
+
+#endif /* __RCAR_CMM_H__ */