diff mbox

[RFC,4/5] drm/bridge: add dw-hdmi cec driver using Hans Verkil's CEC code

Message ID E1bYDEs-0004rs-FP@rmk-PC.armlinux.org.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Russell King Aug. 12, 2016, 2:15 p.m. UTC
Add a CEC driver for the dw-hdmi hardware using Hans Verkil's CEC
implementation.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
---
 drivers/gpu/drm/bridge/Kconfig            |   7 +
 drivers/gpu/drm/bridge/Makefile           |   1 +
 drivers/gpu/drm/bridge/dw-hdmi-cec.c      | 344 ++++++++++++++++++++++++++++++
 drivers/gpu/drm/bridge/dw-hdmi.c          |  64 +++++-
 include/linux/platform_data/dw_hdmi-cec.h |  16 ++
 5 files changed, 421 insertions(+), 11 deletions(-)
 create mode 100644 drivers/gpu/drm/bridge/dw-hdmi-cec.c
 create mode 100644 include/linux/platform_data/dw_hdmi-cec.h

Comments

Hans Verkuil (hansverk) Aug. 12, 2016, 2:25 p.m. UTC | #1
On 08/12/2016 04:15 PM, Russell King wrote:
> Add a CEC driver for the dw-hdmi hardware using Hans Verkil's CEC

That's Verkuil :-)

BTW, since cec is part of the media subsystem please include linux-media for the next round.

Regards,

	Hans
Russell King (Oracle) Aug. 12, 2016, 2:26 p.m. UTC | #2
On Fri, Aug 12, 2016 at 04:25:02PM +0200, Hans Verkuil wrote:
> On 08/12/2016 04:15 PM, Russell King wrote:
> >Add a CEC driver for the dw-hdmi hardware using Hans Verkil's CEC
> 
> That's Verkuil :-)

Oops, sorry about that.

> BTW, since cec is part of the media subsystem please include linux-media
> for the next round.

I can't guarantee that, I'm quite forgetful.
Hans Verkuil Aug. 23, 2016, 7:21 a.m. UTC | #3
Hi Russell,

On 08/12/2016 04:15 PM, Russell King wrote:
> Add a CEC driver for the dw-hdmi hardware using Hans Verkil's CEC
> implementation.
> 
> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
> ---
>  drivers/gpu/drm/bridge/Kconfig            |   7 +
>  drivers/gpu/drm/bridge/Makefile           |   1 +
>  drivers/gpu/drm/bridge/dw-hdmi-cec.c      | 344 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/bridge/dw-hdmi.c          |  64 +++++-
>  include/linux/platform_data/dw_hdmi-cec.h |  16 ++
>  5 files changed, 421 insertions(+), 11 deletions(-)
>  create mode 100644 drivers/gpu/drm/bridge/dw-hdmi-cec.c
>  create mode 100644 include/linux/platform_data/dw_hdmi-cec.h
> 

<snip>

> +static unsigned int parse_hdmi_addr(const struct edid *edid)
> +{
> +	if (!edid || edid->extensions == 0)
> +		return (u16)~0;
> +
> +	return cec_get_edid_phys_addr((u8 *)edid,
> +				EDID_LENGTH * (edid->extensions + 1), NULL);
> +}
> +
> +static int dw_hdmi_cec_notify(struct notifier_block *nb, unsigned long event,
> +			      void *data)
> +{
> +	struct dw_hdmi_cec *cec = container_of(nb, struct dw_hdmi_cec, nb);
> +	union hdmi_event *event_block = data;
> +	unsigned int phys;
> +
> +	dev_info(event_block->base.source, "event %lu\n", event);
> +
> +	if (event_block->base.source != cec->adap->devnode.parent)
> +		return NOTIFY_OK;
> +
> +	switch (event) {
> +	case HDMI_CONNECTED:
> +		break;
> +
> +	case HDMI_DISCONNECTED:
> +		cec_s_phys_addr(cec->adap, CEC_PHYS_ADDR_INVALID, false);
> +		break;
> +
> +	case HDMI_NEW_EDID:
> +		phys = parse_hdmi_addr(event_block->edid.edid);
> +		cec_s_phys_addr(cec->adap, phys, false);
> +		break;
> +	}
> +
> +	return NOTIFY_OK;
> +}

Wouldn't it make a lot of sense to integrate this into the cec framework?

All you need is to pass an hdmi_notifier_dev as argument to cec_allocate_adapter()
and you can integrate this.

If you are OK with that, then I can make patches for that.

Regards,

	Hans
Russell King (Oracle) Aug. 23, 2016, 7:59 a.m. UTC | #4
On Tue, Aug 23, 2016 at 09:21:17AM +0200, Hans Verkuil wrote:
> Hi Russell,
> 
> On 08/12/2016 04:15 PM, Russell King wrote:
> > Add a CEC driver for the dw-hdmi hardware using Hans Verkil's CEC
> > implementation.
> > 
> > Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
> > ---
> >  drivers/gpu/drm/bridge/Kconfig            |   7 +
> >  drivers/gpu/drm/bridge/Makefile           |   1 +
> >  drivers/gpu/drm/bridge/dw-hdmi-cec.c      | 344 ++++++++++++++++++++++++++++++
> >  drivers/gpu/drm/bridge/dw-hdmi.c          |  64 +++++-
> >  include/linux/platform_data/dw_hdmi-cec.h |  16 ++
> >  5 files changed, 421 insertions(+), 11 deletions(-)
> >  create mode 100644 drivers/gpu/drm/bridge/dw-hdmi-cec.c
> >  create mode 100644 include/linux/platform_data/dw_hdmi-cec.h
> > 
> 
> <snip>
> 
> > +static unsigned int parse_hdmi_addr(const struct edid *edid)
> > +{
> > +	if (!edid || edid->extensions == 0)
> > +		return (u16)~0;
> > +
> > +	return cec_get_edid_phys_addr((u8 *)edid,
> > +				EDID_LENGTH * (edid->extensions + 1), NULL);
> > +}
> > +
> > +static int dw_hdmi_cec_notify(struct notifier_block *nb, unsigned long event,
> > +			      void *data)
> > +{
> > +	struct dw_hdmi_cec *cec = container_of(nb, struct dw_hdmi_cec, nb);
> > +	union hdmi_event *event_block = data;
> > +	unsigned int phys;
> > +
> > +	dev_info(event_block->base.source, "event %lu\n", event);
> > +
> > +	if (event_block->base.source != cec->adap->devnode.parent)
> > +		return NOTIFY_OK;
> > +
> > +	switch (event) {
> > +	case HDMI_CONNECTED:
> > +		break;
> > +
> > +	case HDMI_DISCONNECTED:
> > +		cec_s_phys_addr(cec->adap, CEC_PHYS_ADDR_INVALID, false);
> > +		break;
> > +
> > +	case HDMI_NEW_EDID:
> > +		phys = parse_hdmi_addr(event_block->edid.edid);
> > +		cec_s_phys_addr(cec->adap, phys, false);
> > +		break;
> > +	}
> > +
> > +	return NOTIFY_OK;
> > +}
> 
> Wouldn't it make a lot of sense to integrate this into the cec framework?
> 
> All you need is to pass an hdmi_notifier_dev as argument to cec_allocate_adapter()
> and you can integrate this.
> 
> If you are OK with that, then I can make patches for that.

It's not just about CEC.  It's also used for passing information between
the video and audio parts, so tying this into CEC is wrong.
Hans Verkuil Aug. 23, 2016, 8:03 a.m. UTC | #5
Hi Russell,

On 08/12/16 16:15, Russell King wrote:
> +	ret = devm_request_threaded_irq(&pdev->dev, cec->irq,
> +					dw_hdmi_cec_hardirq,
> +					dw_hdmi_cec_thread, IRQF_SHARED,
> +					DEV_NAME, cec->adap);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = cec_register_adapter(cec->adap);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * CEC documentation says we must not call cec_delete_adapter
> +	 * after a successful call to cec_register_adapter().
> +	 */
> +	devm_remove_action(&pdev->dev, dw_hdmi_cec_del, cec);
> +
> +	hdmi_register_notifier(&cec->nb);

The notifier is registered here, but who provides CEC with the initial
physical address? As I understand it, it only tells you when things change,
not what the initial state is.

Regards,

	Hans
Hans Verkuil (hansverk) Aug. 23, 2016, 8:05 a.m. UTC | #6
On 08/23/16 09:59, Russell King - ARM Linux wrote:
> On Tue, Aug 23, 2016 at 09:21:17AM +0200, Hans Verkuil wrote:
>> Hi Russell,
>>
>> On 08/12/2016 04:15 PM, Russell King wrote:
>>> Add a CEC driver for the dw-hdmi hardware using Hans Verkil's CEC
>>> implementation.
>>>
>>> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
>>> ---
>>>  drivers/gpu/drm/bridge/Kconfig            |   7 +
>>>  drivers/gpu/drm/bridge/Makefile           |   1 +
>>>  drivers/gpu/drm/bridge/dw-hdmi-cec.c      | 344 ++++++++++++++++++++++++++++++
>>>  drivers/gpu/drm/bridge/dw-hdmi.c          |  64 +++++-
>>>  include/linux/platform_data/dw_hdmi-cec.h |  16 ++
>>>  5 files changed, 421 insertions(+), 11 deletions(-)
>>>  create mode 100644 drivers/gpu/drm/bridge/dw-hdmi-cec.c
>>>  create mode 100644 include/linux/platform_data/dw_hdmi-cec.h
>>>
>>
>> <snip>
>>
>>> +static unsigned int parse_hdmi_addr(const struct edid *edid)
>>> +{
>>> +	if (!edid || edid->extensions == 0)
>>> +		return (u16)~0;
>>> +
>>> +	return cec_get_edid_phys_addr((u8 *)edid,
>>> +				EDID_LENGTH * (edid->extensions + 1), NULL);
>>> +}
>>> +
>>> +static int dw_hdmi_cec_notify(struct notifier_block *nb, unsigned long event,
>>> +			      void *data)
>>> +{
>>> +	struct dw_hdmi_cec *cec = container_of(nb, struct dw_hdmi_cec, nb);
>>> +	union hdmi_event *event_block = data;
>>> +	unsigned int phys;
>>> +
>>> +	dev_info(event_block->base.source, "event %lu\n", event);
>>> +
>>> +	if (event_block->base.source != cec->adap->devnode.parent)
>>> +		return NOTIFY_OK;
>>> +
>>> +	switch (event) {
>>> +	case HDMI_CONNECTED:
>>> +		break;
>>> +
>>> +	case HDMI_DISCONNECTED:
>>> +		cec_s_phys_addr(cec->adap, CEC_PHYS_ADDR_INVALID, false);
>>> +		break;
>>> +
>>> +	case HDMI_NEW_EDID:
>>> +		phys = parse_hdmi_addr(event_block->edid.edid);
>>> +		cec_s_phys_addr(cec->adap, phys, false);
>>> +		break;
>>> +	}
>>> +
>>> +	return NOTIFY_OK;
>>> +}
>>
>> Wouldn't it make a lot of sense to integrate this into the cec framework?
>>
>> All you need is to pass an hdmi_notifier_dev as argument to cec_allocate_adapter()
>> and you can integrate this.
>>
>> If you are OK with that, then I can make patches for that.
> 
> It's not just about CEC.  It's also used for passing information between
> the video and audio parts, so tying this into CEC is wrong.

I'm not saying that the hdmi notifier should be integrated, just that the
CEC core can register itself as a notifier and handle cec_s_phys_addr.

Regards,

	Hans
Russell King (Oracle) Aug. 31, 2016, 12:28 p.m. UTC | #7
On Tue, Aug 23, 2016 at 10:03:03AM +0200, Hans Verkuil wrote:
> Hi Russell,
> 
> On 08/12/16 16:15, Russell King wrote:
> > +	ret = devm_request_threaded_irq(&pdev->dev, cec->irq,
> > +					dw_hdmi_cec_hardirq,
> > +					dw_hdmi_cec_thread, IRQF_SHARED,
> > +					DEV_NAME, cec->adap);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	ret = cec_register_adapter(cec->adap);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	/*
> > +	 * CEC documentation says we must not call cec_delete_adapter
> > +	 * after a successful call to cec_register_adapter().
> > +	 */
> > +	devm_remove_action(&pdev->dev, dw_hdmi_cec_del, cec);
> > +
> > +	hdmi_register_notifier(&cec->nb);
> 
> The notifier is registered here, but who provides CEC with the initial
> physical address? As I understand it, it only tells you when things change,
> not what the initial state is.

Correct, that's a short-coming of this.  Solving that is not really
an easy problem - the hdmi notifiers don't track the state (they
aren't really aware of state themselves), nor do they track who the
originator of the messages is (again, because they don't track state.)

Fixing that requires a much more complex solution - I don't think I've
time to solve that (as illustrated by this reply taking over a week.)

So, we can either decide that we're not going to merge any CEC drivers
and other HDMI audio drivers until we solve this problem, denying people
the ability to use CEC, or we can merge what we have now and work on
solving the problem later.
Russell King (Oracle) Aug. 31, 2016, 12:28 p.m. UTC | #8
On Tue, Aug 23, 2016 at 10:05:45AM +0200, Hans Verkuil wrote:
> 
> 
> On 08/23/16 09:59, Russell King - ARM Linux wrote:
> > On Tue, Aug 23, 2016 at 09:21:17AM +0200, Hans Verkuil wrote:
> >> Hi Russell,
> >>
> >> On 08/12/2016 04:15 PM, Russell King wrote:
> >>> Add a CEC driver for the dw-hdmi hardware using Hans Verkil's CEC
> >>> implementation.
> >>>
> >>> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
> >>> ---
> >>>  drivers/gpu/drm/bridge/Kconfig            |   7 +
> >>>  drivers/gpu/drm/bridge/Makefile           |   1 +
> >>>  drivers/gpu/drm/bridge/dw-hdmi-cec.c      | 344 ++++++++++++++++++++++++++++++
> >>>  drivers/gpu/drm/bridge/dw-hdmi.c          |  64 +++++-
> >>>  include/linux/platform_data/dw_hdmi-cec.h |  16 ++
> >>>  5 files changed, 421 insertions(+), 11 deletions(-)
> >>>  create mode 100644 drivers/gpu/drm/bridge/dw-hdmi-cec.c
> >>>  create mode 100644 include/linux/platform_data/dw_hdmi-cec.h
> >>>
> >>
> >> <snip>
> >>
> >>> +static unsigned int parse_hdmi_addr(const struct edid *edid)
> >>> +{
> >>> +	if (!edid || edid->extensions == 0)
> >>> +		return (u16)~0;
> >>> +
> >>> +	return cec_get_edid_phys_addr((u8 *)edid,
> >>> +				EDID_LENGTH * (edid->extensions + 1), NULL);
> >>> +}
> >>> +
> >>> +static int dw_hdmi_cec_notify(struct notifier_block *nb, unsigned long event,
> >>> +			      void *data)
> >>> +{
> >>> +	struct dw_hdmi_cec *cec = container_of(nb, struct dw_hdmi_cec, nb);
> >>> +	union hdmi_event *event_block = data;
> >>> +	unsigned int phys;
> >>> +
> >>> +	dev_info(event_block->base.source, "event %lu\n", event);
> >>> +
> >>> +	if (event_block->base.source != cec->adap->devnode.parent)
> >>> +		return NOTIFY_OK;
> >>> +
> >>> +	switch (event) {
> >>> +	case HDMI_CONNECTED:
> >>> +		break;
> >>> +
> >>> +	case HDMI_DISCONNECTED:
> >>> +		cec_s_phys_addr(cec->adap, CEC_PHYS_ADDR_INVALID, false);
> >>> +		break;
> >>> +
> >>> +	case HDMI_NEW_EDID:
> >>> +		phys = parse_hdmi_addr(event_block->edid.edid);
> >>> +		cec_s_phys_addr(cec->adap, phys, false);
> >>> +		break;
> >>> +	}
> >>> +
> >>> +	return NOTIFY_OK;
> >>> +}
> >>
> >> Wouldn't it make a lot of sense to integrate this into the cec framework?
> >>
> >> All you need is to pass an hdmi_notifier_dev as argument to cec_allocate_adapter()
> >> and you can integrate this.
> >>
> >> If you are OK with that, then I can make patches for that.
> > 
> > It's not just about CEC.  It's also used for passing information between
> > the video and audio parts, so tying this into CEC is wrong.
> 
> I'm not saying that the hdmi notifier should be integrated, just that the
> CEC core can register itself as a notifier and handle cec_s_phys_addr.

Yes, that would decrease the amount of code duplication.
diff mbox

Patch

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index 6d97d9f2b164..3ad19d16f4ca 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -33,6 +33,13 @@  config DRM_DW_HDMI_AHB_AUDIO
 	  Designware HDMI block.  This is used in conjunction with
 	  the i.MX6 HDMI driver.
 
+config DRM_DW_HDMI_CEC
+	tristate "Synopsis Designware CEC interface"
+	depends on DRM_DW_HDMI && MEDIA_CEC
+	help
+	  Support the CE interface which is part of the Synopsis
+	  Designware HDMI block.
+
 config DRM_NXP_PTN3460
 	tristate "NXP PTN3460 DP/LVDS bridge"
 	depends on OF
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 96b13b30e6ab..4869441d35f4 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -3,6 +3,7 @@  ccflags-y := -Iinclude/drm
 obj-$(CONFIG_DRM_ANALOGIX_ANX78XX) += analogix-anx78xx.o
 obj-$(CONFIG_DRM_DW_HDMI) += dw-hdmi.o
 obj-$(CONFIG_DRM_DW_HDMI_AHB_AUDIO) += dw-hdmi-ahb-audio.o
+obj-$(CONFIG_DRM_DW_HDMI_CEC) += dw-hdmi-cec.o
 obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
 obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
 obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
diff --git a/drivers/gpu/drm/bridge/dw-hdmi-cec.c b/drivers/gpu/drm/bridge/dw-hdmi-cec.c
new file mode 100644
index 000000000000..9d6b8daa584d
--- /dev/null
+++ b/drivers/gpu/drm/bridge/dw-hdmi-cec.c
@@ -0,0 +1,344 @@ 
+/* http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/
+ * tree/drivers/mxc/hdmi-cec/mxc_hdmi-cec.c?h=imx_3.0.35_4.1.0 */
+#include <linux/hdmi-notifier.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/platform_data/dw_hdmi-cec.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include <drm/drm_edid.h>
+
+#include <media/cec.h>
+#include <media/cec-edid.h>
+
+#define DEV_NAME "mxc_hdmi_cec"
+
+enum {
+	HDMI_IH_CEC_STAT0	= 0x0106,
+	HDMI_IH_MUTE_CEC_STAT0	= 0x0186,
+
+	HDMI_CEC_CTRL		= 0x7d00,
+	CEC_CTRL_START		= BIT(0),
+	CEC_CTRL_NORMAL		= 1 << 1,
+
+	HDMI_CEC_STAT		= 0x7d01,
+	CEC_STAT_DONE		= BIT(0),
+	CEC_STAT_EOM		= BIT(1),
+	CEC_STAT_NACK		= BIT(2),
+	CEC_STAT_ARBLOST	= BIT(3),
+	CEC_STAT_ERROR_INIT	= BIT(4),
+	CEC_STAT_ERROR_FOLL	= BIT(5),
+	CEC_STAT_WAKEUP		= BIT(6),
+
+	HDMI_CEC_MASK		= 0x7d02,
+	HDMI_CEC_POLARITY	= 0x7d03,
+	HDMI_CEC_INT		= 0x7d04,
+	HDMI_CEC_ADDR_L		= 0x7d05,
+	HDMI_CEC_ADDR_H		= 0x7d06,
+	HDMI_CEC_TX_CNT		= 0x7d07,
+	HDMI_CEC_RX_CNT		= 0x7d08,
+	HDMI_CEC_TX_DATA0	= 0x7d10,
+	HDMI_CEC_RX_DATA0	= 0x7d20,
+	HDMI_CEC_LOCK		= 0x7d30,
+	HDMI_CEC_WKUPCTRL	= 0x7d31,
+};
+
+struct dw_hdmi_cec {
+	void __iomem *base;
+	u32 addresses;
+	struct cec_adapter *adap;
+	struct cec_msg rx_msg;
+	unsigned int tx_status;
+	bool tx_done;
+	bool rx_done;
+	const struct dw_hdmi_cec_ops *ops;
+	void *ops_data;
+	int retries;
+	int irq;
+	struct notifier_block nb;
+};
+
+static int dw_hdmi_cec_log_addr(struct cec_adapter *adap, u8 logical_addr)
+{
+	struct dw_hdmi_cec *cec = adap->priv;
+	u32 addresses;
+
+	if (logical_addr == CEC_LOG_ADDR_INVALID)
+		addresses = cec->addresses = BIT(15);
+	else
+		addresses = cec->addresses |= BIT(logical_addr);
+
+	writeb_relaxed(addresses & 255, cec->base + HDMI_CEC_ADDR_L);
+	writeb_relaxed(addresses >> 8, cec->base + HDMI_CEC_ADDR_H);
+
+	return 0;
+}
+
+static int dw_hdmi_cec_transmit(struct cec_adapter *adap, u8 attempts,
+				u32 signal_free_time, struct cec_msg *msg)
+{
+	struct dw_hdmi_cec *cec = adap->priv;
+	unsigned i;
+
+	cec->retries = attempts;
+
+	for (i = 0; i < msg->len; i++)
+		writeb_relaxed(msg->msg[i], cec->base + HDMI_CEC_TX_DATA0 + i);
+
+	writeb_relaxed(msg->len, cec->base + HDMI_CEC_TX_CNT);
+	writeb_relaxed(CEC_CTRL_NORMAL | CEC_CTRL_START, cec->base + HDMI_CEC_CTRL);
+
+	return 0;
+}
+
+static irqreturn_t dw_hdmi_cec_hardirq(int irq, void *data)
+{
+	struct cec_adapter *adap = data;
+	struct dw_hdmi_cec *cec = adap->priv;
+	unsigned stat = readb_relaxed(cec->base + HDMI_IH_CEC_STAT0);
+	irqreturn_t ret = IRQ_HANDLED;
+
+	if (stat == 0)
+		return IRQ_NONE;
+
+	writeb_relaxed(stat, cec->base + HDMI_IH_CEC_STAT0);
+
+	if (stat & CEC_STAT_ERROR_INIT) {
+		if (cec->retries) {
+			unsigned v = readb_relaxed(cec->base + HDMI_CEC_CTRL);
+			writeb_relaxed(v | CEC_CTRL_START, cec->base + HDMI_CEC_CTRL);
+			cec->retries -= 1;
+		} else {
+			cec->tx_status = CEC_TX_STATUS_MAX_RETRIES;
+			cec->tx_done = true;
+			ret = IRQ_WAKE_THREAD;
+		}
+	} else if (stat & CEC_STAT_DONE) {
+		cec->tx_status = CEC_TX_STATUS_OK;
+		cec->tx_done = true;
+		ret = IRQ_WAKE_THREAD;
+	} else if (stat & CEC_STAT_NACK) {
+		cec->tx_status = CEC_TX_STATUS_NACK;
+		cec->tx_done = true;
+		ret = IRQ_WAKE_THREAD;
+	}
+
+	if (stat & CEC_STAT_EOM) {
+		unsigned len, i;
+		void *base = cec->base;
+
+		len = readb_relaxed(base + HDMI_CEC_RX_CNT);
+		if (len > sizeof(cec->rx_msg.msg))
+			len = sizeof(cec->rx_msg.msg);
+
+		for (i = 0; i < len; i++)
+			cec->rx_msg.msg[i] =
+				readb_relaxed(base + HDMI_CEC_RX_DATA0 + i);
+
+		writeb_relaxed(0, base + HDMI_CEC_LOCK);
+
+		cec->rx_msg.len = len;
+		smp_wmb();
+		cec->rx_done = true;
+
+		ret = IRQ_WAKE_THREAD;
+	}
+
+	return ret;
+}
+
+static irqreturn_t dw_hdmi_cec_thread(int irq, void *data)
+{
+	struct cec_adapter *adap = data;
+	struct dw_hdmi_cec *cec = adap->priv;
+
+	if (cec->tx_done) {
+		cec->tx_done = false;
+		cec_transmit_done(adap, cec->tx_status, 0, 0, 0, 0);
+	}
+	if (cec->rx_done) {
+		cec->rx_done = false;
+		smp_rmb();
+		cec_received_msg(adap, &cec->rx_msg);
+	}
+	return IRQ_HANDLED;
+}
+
+static int dw_hdmi_cec_enable(struct cec_adapter *adap, bool enable)
+{
+	struct dw_hdmi_cec *cec = adap->priv;
+
+	if (!enable) {
+		writeb_relaxed(~0, cec->base + HDMI_CEC_MASK);
+		writeb_relaxed(~0, cec->base + HDMI_IH_MUTE_CEC_STAT0);
+		writeb_relaxed(0, cec->base + HDMI_CEC_POLARITY);
+
+		cec->ops->disable(cec->ops_data);
+	} else {
+		unsigned irqs;
+
+		writeb_relaxed(0, cec->base + HDMI_CEC_CTRL);
+		writeb_relaxed(~0, cec->base + HDMI_IH_CEC_STAT0);
+		writeb_relaxed(0, cec->base + HDMI_CEC_LOCK);
+
+		dw_hdmi_cec_log_addr(cec->adap, CEC_LOG_ADDR_INVALID);
+
+		cec->ops->enable(cec->ops_data);
+
+		irqs = CEC_STAT_ERROR_INIT | CEC_STAT_NACK | CEC_STAT_EOM |
+		       CEC_STAT_DONE;
+		writeb_relaxed(irqs, cec->base + HDMI_CEC_POLARITY);
+		writeb_relaxed(~irqs, cec->base + HDMI_CEC_MASK);
+		writeb_relaxed(~irqs, cec->base + HDMI_IH_MUTE_CEC_STAT0);
+	}
+	return 0;
+}
+
+static const struct cec_adap_ops dw_hdmi_cec_ops = {
+	.adap_enable = dw_hdmi_cec_enable,
+	.adap_log_addr = dw_hdmi_cec_log_addr,
+	.adap_transmit = dw_hdmi_cec_transmit,
+};
+
+static unsigned int parse_hdmi_addr(const struct edid *edid)
+{
+	if (!edid || edid->extensions == 0)
+		return (u16)~0;
+
+	return cec_get_edid_phys_addr((u8 *)edid,
+				EDID_LENGTH * (edid->extensions + 1), NULL);
+}
+
+static int dw_hdmi_cec_notify(struct notifier_block *nb, unsigned long event,
+			      void *data)
+{
+	struct dw_hdmi_cec *cec = container_of(nb, struct dw_hdmi_cec, nb);
+	union hdmi_event *event_block = data;
+	unsigned int phys;
+
+	dev_info(event_block->base.source, "event %lu\n", event);
+
+	if (event_block->base.source != cec->adap->devnode.parent)
+		return NOTIFY_OK;
+
+	switch (event) {
+	case HDMI_CONNECTED:
+		break;
+
+	case HDMI_DISCONNECTED:
+		cec_s_phys_addr(cec->adap, CEC_PHYS_ADDR_INVALID, false);
+		break;
+
+	case HDMI_NEW_EDID:
+		phys = parse_hdmi_addr(event_block->edid.edid);
+		cec_s_phys_addr(cec->adap, phys, false);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static void dw_hdmi_cec_del(void *data)
+{
+	struct dw_hdmi_cec *cec = data;
+
+	cec_delete_adapter(cec->adap);
+}
+
+static int dw_hdmi_cec_probe(struct platform_device *pdev)
+{
+	struct dw_hdmi_cec_data *data = dev_get_platdata(&pdev->dev);
+	struct dw_hdmi_cec *cec;
+	int ret;
+
+	if (!data)
+		return -ENXIO;
+
+	/*
+	 * Our device is just a convenience - we want to link to the real
+	 * hardware device here, so that userspace can see the association
+	 * between the HDMI hardware and its associated CEC chardev.
+	 */
+	cec = devm_kzalloc(&pdev->dev, sizeof(*cec), GFP_KERNEL);
+	if (!cec)
+		return -ENOMEM;
+
+	cec->base = data->base;
+	cec->irq = data->irq;
+	cec->ops = data->ops;
+	cec->ops_data = data->ops_data;
+	cec->nb.notifier_call = dw_hdmi_cec_notify;
+
+	platform_set_drvdata(pdev, cec);
+
+	writeb_relaxed(0, cec->base + HDMI_CEC_TX_CNT);
+	writeb_relaxed(~0, cec->base + HDMI_CEC_MASK);
+	writeb_relaxed(~0, cec->base + HDMI_IH_MUTE_CEC_STAT0);
+	writeb_relaxed(0, cec->base + HDMI_CEC_POLARITY);
+
+	cec->adap = cec_allocate_adapter(&dw_hdmi_cec_ops, cec, "dw_hdmi",
+					 CEC_CAP_LOG_ADDRS | CEC_CAP_TRANSMIT |
+					 CEC_CAP_RC, CEC_MAX_LOG_ADDRS,
+					 pdev->dev.parent);
+	if (IS_ERR(cec->adap))
+		return PTR_ERR(cec->adap);
+
+	/* override the module pointer */
+	cec->adap->owner = THIS_MODULE;
+
+	ret = devm_add_action(&pdev->dev, dw_hdmi_cec_del, cec);
+	if (ret) {
+		cec_delete_adapter(cec->adap);
+		return ret;
+	}
+
+	ret = devm_request_threaded_irq(&pdev->dev, cec->irq,
+					dw_hdmi_cec_hardirq,
+					dw_hdmi_cec_thread, IRQF_SHARED,
+					DEV_NAME, cec->adap);
+	if (ret < 0)
+		return ret;
+
+	ret = cec_register_adapter(cec->adap);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * CEC documentation says we must not call cec_delete_adapter
+	 * after a successful call to cec_register_adapter().
+	 */
+	devm_remove_action(&pdev->dev, dw_hdmi_cec_del, cec);
+
+	hdmi_register_notifier(&cec->nb);
+
+	return 0;
+}
+
+static int dw_hdmi_cec_remove(struct platform_device *pdev)
+{
+	struct dw_hdmi_cec *cec = platform_get_drvdata(pdev);
+
+	hdmi_unregister_notifier(&cec->nb);
+	cec_unregister_adapter(cec->adap);
+
+	return 0;
+}
+
+static struct platform_driver dw_hdmi_cec_driver = {
+	.probe	= dw_hdmi_cec_probe,
+	.remove	= dw_hdmi_cec_remove,
+	.driver = {
+		.name = "dw-hdmi-cec",
+		.owner = THIS_MODULE,
+	},
+};
+module_platform_driver(dw_hdmi_cec_driver);
+
+MODULE_AUTHOR("Russell King <rmk+kernel@arm.linux.org.uk>");
+MODULE_DESCRIPTION("Synopsis Designware HDMI CEC driver for i.MX");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS(PLATFORM_MODULE_PREFIX "dw-hdmi-cec");
diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
index cb6e03efbebf..1ad58e37c0b3 100644
--- a/drivers/gpu/drm/bridge/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/dw-hdmi.c
@@ -19,6 +19,7 @@ 
 #include <linux/hdmi-notifier.h>
 #include <linux/mutex.h>
 #include <linux/of_device.h>
+#include <linux/platform_data/dw_hdmi-cec.h>
 #include <linux/spinlock.h>
 
 #include <drm/drm_of.h>
@@ -108,6 +109,7 @@  struct dw_hdmi {
 	struct drm_bridge *bridge;
 
 	struct platform_device *audio;
+	struct platform_device *cec;
 	enum dw_hdmi_devtype dev_type;
 	struct device *dev;
 	struct clk *isfr_clk;
@@ -119,6 +121,7 @@  struct dw_hdmi {
 	int vic;
 
 	u8 edid[HDMI_EDID_LEN];
+	u8 mc_clkdis;
 	bool cable_plugin;
 
 	bool phy_enabled;
@@ -1108,8 +1111,6 @@  static void dw_hdmi_phy_disable(struct dw_hdmi *hdmi)
 /* HDMI Initialization Step B.4 */
 static void dw_hdmi_enable_video_path(struct dw_hdmi *hdmi)
 {
-	u8 clkdis;
-
 	/* control period minimum duration */
 	hdmi_writeb(hdmi, 12, HDMI_FC_CTRLDUR);
 	hdmi_writeb(hdmi, 32, HDMI_FC_EXCTRLDUR);
@@ -1121,23 +1122,28 @@  static void dw_hdmi_enable_video_path(struct dw_hdmi *hdmi)
 	hdmi_writeb(hdmi, 0x21, HDMI_FC_CH2PREAM);
 
 	/* Enable pixel clock and tmds data path */
-	clkdis = 0x7F;
-	clkdis &= ~HDMI_MC_CLKDIS_PIXELCLK_DISABLE;
-	hdmi_writeb(hdmi, clkdis, HDMI_MC_CLKDIS);
+	hdmi->mc_clkdis |= HDMI_MC_CLKDIS_HDCPCLK_DISABLE |
+			   HDMI_MC_CLKDIS_CSCCLK_DISABLE |
+			   HDMI_MC_CLKDIS_AUDCLK_DISABLE |
+			   HDMI_MC_CLKDIS_PREPCLK_DISABLE |
+			   HDMI_MC_CLKDIS_TMDSCLK_DISABLE;
+	hdmi->mc_clkdis &= ~HDMI_MC_CLKDIS_PIXELCLK_DISABLE;
+	hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
 
-	clkdis &= ~HDMI_MC_CLKDIS_TMDSCLK_DISABLE;
-	hdmi_writeb(hdmi, clkdis, HDMI_MC_CLKDIS);
+	hdmi->mc_clkdis &= ~HDMI_MC_CLKDIS_TMDSCLK_DISABLE;
+	hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
 
 	/* Enable csc path */
 	if (is_color_space_conversion(hdmi)) {
-		clkdis &= ~HDMI_MC_CLKDIS_CSCCLK_DISABLE;
-		hdmi_writeb(hdmi, clkdis, HDMI_MC_CLKDIS);
+		hdmi->mc_clkdis &= ~HDMI_MC_CLKDIS_CSCCLK_DISABLE;
+		hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
 	}
 }
 
 static void hdmi_enable_audio_clk(struct dw_hdmi *hdmi)
 {
-	hdmi_modb(hdmi, 0, HDMI_MC_CLKDIS_AUDCLK_DISABLE, HDMI_MC_CLKDIS);
+	hdmi->mc_clkdis &= ~HDMI_MC_CLKDIS_AUDCLK_DISABLE;
+	hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
 }
 
 /* Workaround to clear the overflow condition */
@@ -1297,7 +1303,6 @@  static void initialize_hdmi_ih_mutes(struct dw_hdmi *hdmi)
 	hdmi_writeb(hdmi, 0xff, HDMI_AUD_HBR_MASK);
 	hdmi_writeb(hdmi, 0xff, HDMI_GP_MASK);
 	hdmi_writeb(hdmi, 0xff, HDMI_A_APIINTMSK);
-	hdmi_writeb(hdmi, 0xff, HDMI_CEC_MASK);
 	hdmi_writeb(hdmi, 0xff, HDMI_I2CM_INT);
 	hdmi_writeb(hdmi, 0xff, HDMI_I2CM_CTLINT);
 
@@ -1666,6 +1671,27 @@  static int dw_hdmi_register(struct drm_device *drm, struct dw_hdmi *hdmi)
 	return 0;
 }
 
+static void dw_hdmi_cec_enable(void *data)
+{
+	struct dw_hdmi *hdmi = data;
+
+	hdmi->mc_clkdis &= ~HDMI_MC_CLKDIS_CECCLK_DISABLE;
+	hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
+}
+
+static void dw_hdmi_cec_disable(void *data)
+{
+	struct dw_hdmi *hdmi = data;
+
+	hdmi->mc_clkdis |= HDMI_MC_CLKDIS_CECCLK_DISABLE;
+	hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
+}
+
+static const struct dw_hdmi_cec_ops dw_hdmi_cec_ops = {
+	.enable = dw_hdmi_cec_enable,
+	.disable = dw_hdmi_cec_disable,
+};
+
 int dw_hdmi_bind(struct device *dev, struct device *master,
 		 void *data, struct drm_encoder *encoder,
 		 struct resource *iores, int irq,
@@ -1676,6 +1702,7 @@  int dw_hdmi_bind(struct device *dev, struct device *master,
 	struct platform_device_info pdevinfo;
 	struct device_node *ddc_node;
 	struct dw_hdmi_audio_data audio;
+	struct dw_hdmi_cec_data cec;
 	struct dw_hdmi *hdmi;
 	int ret;
 	u32 val = 1;
@@ -1694,6 +1721,7 @@  int dw_hdmi_bind(struct device *dev, struct device *master,
 	hdmi->disabled = true;
 	hdmi->rxsense = true;
 	hdmi->phy_mask = (u8)~(HDMI_PHY_HPD | HDMI_PHY_RX_SENSE);
+	hdmi->mc_clkdis = 0x7f;
 
 	mutex_init(&hdmi->mutex);
 	mutex_init(&hdmi->audio_mutex);
@@ -1820,6 +1848,18 @@  int dw_hdmi_bind(struct device *dev, struct device *master,
 		hdmi->audio = platform_device_register_full(&pdevinfo);
 	}
 
+	cec.base = hdmi->regs;
+	cec.irq = irq;
+	cec.ops = &dw_hdmi_cec_ops;
+	cec.ops_data = hdmi;
+
+	pdevinfo.name = "dw-hdmi-cec";
+	pdevinfo.data = &cec;
+	pdevinfo.size_data = sizeof(cec);
+	pdevinfo.dma_mask = 0;
+
+	hdmi->cec = platform_device_register_full(&pdevinfo);
+
 	dev_set_drvdata(dev, hdmi);
 
 	return 0;
@@ -1839,6 +1879,8 @@  void dw_hdmi_unbind(struct device *dev, struct device *master, void *data)
 
 	if (hdmi->audio && !IS_ERR(hdmi->audio))
 		platform_device_unregister(hdmi->audio);
+	if (!IS_ERR(hdmi->cec))
+		platform_device_unregister(hdmi->cec);
 
 	/* Disable all interrupts */
 	hdmi_writeb(hdmi, ~0, HDMI_IH_MUTE_PHY_STAT0);
diff --git a/include/linux/platform_data/dw_hdmi-cec.h b/include/linux/platform_data/dw_hdmi-cec.h
new file mode 100644
index 000000000000..5ff40cc237a8
--- /dev/null
+++ b/include/linux/platform_data/dw_hdmi-cec.h
@@ -0,0 +1,16 @@ 
+#ifndef DW_HDMI_CEC_H
+#define DW_HDMI_CEC_H
+
+struct dw_hdmi_cec_ops {
+	void (*enable)(void *);
+	void (*disable)(void *);
+};
+
+struct dw_hdmi_cec_data {
+	void __iomem *base;
+	int irq;
+	const struct dw_hdmi_cec_ops *ops;
+	void *ops_data;
+};
+
+#endif