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[v17,2/4] dmaengine: tegra: Add tegra gpcdma driver

Message ID 1643474453-32619-3-git-send-email-akhilrajeev@nvidia.com (mailing list archive)
State Superseded
Headers show
Series Add NVIDIA Tegra GPC-DMA driver | expand

Commit Message

Akhil R Jan. 29, 2022, 4:40 p.m. UTC
Adding GPC DMA controller driver for Tegra186 and Tegra194. The driver
supports dma transfers between memory to memory, IO peripheral to memory
and memory to IO peripheral.

Co-developed-by: Pavan Kunapuli <pkunapuli@nvidia.com>
Signed-off-by: Pavan Kunapuli <pkunapuli@nvidia.com>
Co-developed-by: Rajesh Gumasta <rgumasta@nvidia.com>
Signed-off-by: Rajesh Gumasta <rgumasta@nvidia.com>
Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
---
 drivers/dma/Kconfig            |   11 +
 drivers/dma/Makefile           |    1 +
 drivers/dma/tegra186-gpc-dma.c | 1488 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1500 insertions(+)
 create mode 100644 drivers/dma/tegra186-gpc-dma.c

Comments

Dmitry Osipenko Jan. 30, 2022, 10:05 a.m. UTC | #1
29.01.2022 19:40, Akhil R пишет:
> +static int tegra_dma_device_pause(struct dma_chan *dc)
> +{
> +	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> +	unsigned long wcount, flags;
> +	int ret = 0;
> +
> +	if (!tdc->tdma->chip_data->hw_support_pause)
> +		return 0;

It's wrong to return zero if pause unsupported, please see what
dmaengine_pause() returns.

> +
> +	spin_lock_irqsave(&tdc->vc.lock, flags);
> +	if (!tdc->dma_desc)
> +		goto out;
> +
> +	ret = tegra_dma_pause(tdc);
> +	if (ret) {
> +		dev_err(tdc2dev(tdc), "DMA pause timed out\n");
> +		goto out;
> +	}
> +
> +	wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
> +	tdc->dma_desc->bytes_xfer +=
> +			tdc->dma_desc->bytes_req - (wcount * 4);

Why transfer is accumulated?

Why do you need to update xfer size at all on pause?

> +
> +out:
> +	spin_unlock_irqrestore(&tdc->vc.lock, flags);
> +
> +	return ret;
> +}

Still nothing prevents interrupt handler to fire during the pause.

What you actually need to do is to disable/enable interrupt. This will
prevent the interrupt racing and then pause/resume may look like this:

static int tegra_dma_device_resume(struct dma_chan *dc)
{
	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
	u32 val;

	if (!tdc->tdma->chip_data->hw_support_pause)
		return -ENOSYS;

	if (!tdc->dma_desc)
		return 0;

	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
	
	enable_irq(tdc->irq);

	return 0;
}

static int tegra_dma_device_pause(struct dma_chan *dc)
{
	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
	u32 val;
	int ret;

	if (!tdc->tdma->chip_data->hw_support_pause)
		return -ENOSYS;

	disable_irq(tdc->irq);

	if (!tdc->dma_desc)
		return 0;

	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
	val |= TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);

	/* Wait until busy bit is de-asserted */
	ret = readl_relaxed_poll_timeout_atomic(
			tdc->chan_base + TEGRA_GPCDMA_CHAN_STATUS,
			val, !(val & TEGRA_GPCDMA_STATUS_BUSY),
			TEGRA_GPCDMA_BURST_COMPLETE_TIME,
			TEGRA_GPCDMA_BURST_COMPLETION_TIMEOUT);
	if (ret) {
		dev_err(tdc2dev(tdc), "DMA pause timed out: %d\n", ret);
		tegra_dma_device_resume(dc);
	}

	return ret;
}
Dmitry Osipenko Jan. 30, 2022, 10:08 a.m. UTC | #2
30.01.2022 13:05, Dmitry Osipenko пишет:
> static int tegra_dma_device_resume(struct dma_chan *dc)
> {
> 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> 	u32 val;
> 
> 	if (!tdc->tdma->chip_data->hw_support_pause)
> 		return -ENOSYS;
> 
> 	if (!tdc->dma_desc)
> 		return 0;
> 
> 	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
> 	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
> 	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
> 	
> 	enable_irq(tdc->irq);

Correction:

if (tdc->dma_desc) {
	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
}

enable_irq(tdc->irq);
Dmitry Osipenko Jan. 30, 2022, 10:13 a.m. UTC | #3
30.01.2022 13:08, Dmitry Osipenko пишет:
> 30.01.2022 13:05, Dmitry Osipenko пишет:
>> static int tegra_dma_device_resume(struct dma_chan *dc)
>> {
>> 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>> 	u32 val;
>>
>> 	if (!tdc->tdma->chip_data->hw_support_pause)
>> 		return -ENOSYS;
>>
>> 	if (!tdc->dma_desc)
>> 		return 0;
>>
>> 	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
>> 	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
>> 	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
>> 	
>> 	enable_irq(tdc->irq);
> 
> Correction:
> 
> if (tdc->dma_desc) {
> 	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
> 	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
> 	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
> }
> 
> enable_irq(tdc->irq);

And apparently, tegra_dma_terminate_all() also needs to take care of
removing the PAUSE bit. Otherwise it won't be possible to unpause
channel after the termination.
Dmitry Osipenko Jan. 30, 2022, 10:17 a.m. UTC | #4
30.01.2022 13:13, Dmitry Osipenko пишет:
> 30.01.2022 13:08, Dmitry Osipenko пишет:
>> 30.01.2022 13:05, Dmitry Osipenko пишет:
>>> static int tegra_dma_device_resume(struct dma_chan *dc)
>>> {
>>> 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>>> 	u32 val;
>>>
>>> 	if (!tdc->tdma->chip_data->hw_support_pause)
>>> 		return -ENOSYS;
>>>
>>> 	if (!tdc->dma_desc)
>>> 		return 0;
>>>
>>> 	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
>>> 	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
>>> 	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
>>> 	
>>> 	enable_irq(tdc->irq);
>>
>> Correction:
>>
>> if (tdc->dma_desc) {
>> 	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
>> 	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
>> 	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
>> }
>>
>> enable_irq(tdc->irq);
> 
> And apparently, tegra_dma_terminate_all() also needs to take care of
> removing the PAUSE bit. Otherwise it won't be possible to unpause
> channel after the termination.

Although, will be easier to just do this in the resume:

val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);

if (val & TEGRA_GPCDMA_CHAN_CSRE_PAUSE) {
	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
}
Dmitry Osipenko Jan. 30, 2022, 10:26 a.m. UTC | #5
30.01.2022 13:05, Dmitry Osipenko пишет:
> Still nothing prevents interrupt handler to fire during the pause.
> 
> What you actually need to do is to disable/enable interrupt. This will
> prevent the interrupt racing and then pause/resume may look like this:

Although, seems this won't work, unfortunately. I see now that
device_pause() doesn't have might_sleep().
Dmitry Osipenko Jan. 30, 2022, 10:33 a.m. UTC | #6
30.01.2022 13:26, Dmitry Osipenko пишет:
> 30.01.2022 13:05, Dmitry Osipenko пишет:
>> Still nothing prevents interrupt handler to fire during the pause.
>>
>> What you actually need to do is to disable/enable interrupt. This will
>> prevent the interrupt racing and then pause/resume may look like this:
> 
> Although, seems this won't work, unfortunately. I see now that
> device_pause() doesn't have might_sleep().
> 

Ah, I see now that the pause/unpause is actually a separate control and
doesn't conflict with "start next transfer".

So you just need to set/unset the pause under lock. And don't touch
tdc->dma_desc. That's it.

static int tegra_dma_device_pause(struct dma_chan *dc)
{
	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
	unsigned long flags;
	u32 val;

	if (!tdc->tdma->chip_data->hw_support_pause)
		return -ENOSYS;

	spin_lock_irqsave(&tdc->vc.lock, flags);

	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
	val |= TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);

	spin_unlock_irqrestore(&tdc->vc.lock, flags);

	return 0;
}

static int tegra_dma_device_resume(struct dma_chan *dc)
{
	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
	unsigned long flags;
	u32 val;

	if (!tdc->tdma->chip_data->hw_support_pause)
		return -ENOSYS;

	spin_lock_irqsave(&tdc->vc.lock, flags);

	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);

	spin_unlock_irqrestore(&tdc->vc.lock, flags);
	
	return 0;
}
Dmitry Osipenko Jan. 30, 2022, 10:38 a.m. UTC | #7
29.01.2022 19:40, Akhil R пишет:
> +static void tegra_dma_chan_synchronize(struct dma_chan *dc)
> +{
> +	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);

	synchronize_irq(tdc->irq);
> +	vchan_synchronize(&tdc->vc);
> +}
Dmitry Osipenko Jan. 30, 2022, 10:39 a.m. UTC | #8
29.01.2022 19:40, Akhil R пишет:
> +static void tegra_dma_free_chan_resources(struct dma_chan *dc)
> +{
> +	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> +
> +	dev_dbg(tdc2dev(tdc), "Freeing channel %d\n", tdc->id);
> +
> +	tegra_dma_terminate_all(dc);

	synchronize_irq(tdc->irq);

> +	tasklet_kill(&tdc->vc.task);
Akhil R Jan. 30, 2022, 4:34 p.m. UTC | #9
> 29.01.2022 19:40, Akhil R пишет:
> > +static int tegra_dma_device_pause(struct dma_chan *dc) {
> > +     struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> > +     unsigned long wcount, flags;
> > +     int ret = 0;
> > +
> > +     if (!tdc->tdma->chip_data->hw_support_pause)
> > +             return 0;
> 
> It's wrong to return zero if pause unsupported, please see what
> dmaengine_pause() returns.
> 
> > +
> > +     spin_lock_irqsave(&tdc->vc.lock, flags);
> > +     if (!tdc->dma_desc)
> > +             goto out;
> > +
> > +     ret = tegra_dma_pause(tdc);
> > +     if (ret) {
> > +             dev_err(tdc2dev(tdc), "DMA pause timed out\n");
> > +             goto out;
> > +     }
> > +
> > +     wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
> > +     tdc->dma_desc->bytes_xfer +=
> > +                     tdc->dma_desc->bytes_req - (wcount * 4);
> 
> Why transfer is accumulated?
> 
> Why do you need to update xfer size at all on pause?

I will verify the calculation. This looks correct only for single sg transaction.

Updating xfer_size is added to support drivers which pause the transaction
and read the status before terminating. 
Eg. https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/amba-pl011.c

Thanks,
Akhil
Akhil R Jan. 30, 2022, 4:43 p.m. UTC | #10
> 30.01.2022 13:26, Dmitry Osipenko пишет:
> > 30.01.2022 13:05, Dmitry Osipenko пишет:
> >> Still nothing prevents interrupt handler to fire during the pause.
> >>
> >> What you actually need to do is to disable/enable interrupt. This
> >> will prevent the interrupt racing and then pause/resume may look like this:
> >
> > Although, seems this won't work, unfortunately. I see now that
> > device_pause() doesn't have might_sleep().
> >
> 
> Ah, I see now that the pause/unpause is actually a separate control and doesn't
> conflict with "start next transfer".
> 
> So you just need to set/unset the pause under lock. And don't touch
> tdc->dma_desc. That's it.
> 
> static int tegra_dma_device_pause(struct dma_chan *dc) {
>         struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>         unsigned long flags;
>         u32 val;
> 
>         if (!tdc->tdma->chip_data->hw_support_pause)
>                 return -ENOSYS;
> 
>         spin_lock_irqsave(&tdc->vc.lock, flags);
> 
>         val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
>         val |= TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
>         tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
> 
>         spin_unlock_irqrestore(&tdc->vc.lock, flags);
> 
>         return 0;
> }
> 
> static int tegra_dma_device_resume(struct dma_chan *dc) {
>         struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>         unsigned long flags;
>         u32 val;
> 
>         if (!tdc->tdma->chip_data->hw_support_pause)
>                 return -ENOSYS;
> 
>         spin_lock_irqsave(&tdc->vc.lock, flags);
> 
>         val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
>         val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
>         tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
> 
>         spin_unlock_irqrestore(&tdc->vc.lock, flags);
> 
>         return 0;
> }

The reason I separated out register writes was to conveniently call those
in dma_start() and terminate_all(). Do you see any issue there?
The recommended way of terminating a transfer in between is to pause
it before disabling the channel.

dma_desc could be NULL while these functions are called. pause() or
resume() is unneeded if there isn't any transfer going on. Moreover,
if we are to calculate the xfer_size, the check would be mandatory.

Agree with the other comments.

Thanks,
Akhil
Dmitry Osipenko Jan. 30, 2022, 11:11 p.m. UTC | #11
30.01.2022 19:34, Akhil R пишет:
>> 29.01.2022 19:40, Akhil R пишет:
>>> +static int tegra_dma_device_pause(struct dma_chan *dc) {
>>> +     struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>>> +     unsigned long wcount, flags;
>>> +     int ret = 0;
>>> +
>>> +     if (!tdc->tdma->chip_data->hw_support_pause)
>>> +             return 0;
>>
>> It's wrong to return zero if pause unsupported, please see what
>> dmaengine_pause() returns.
>>
>>> +
>>> +     spin_lock_irqsave(&tdc->vc.lock, flags);
>>> +     if (!tdc->dma_desc)
>>> +             goto out;
>>> +
>>> +     ret = tegra_dma_pause(tdc);
>>> +     if (ret) {
>>> +             dev_err(tdc2dev(tdc), "DMA pause timed out\n");
>>> +             goto out;
>>> +     }
>>> +
>>> +     wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
>>> +     tdc->dma_desc->bytes_xfer +=
>>> +                     tdc->dma_desc->bytes_req - (wcount * 4);
>>
>> Why transfer is accumulated?
>>
>> Why do you need to update xfer size at all on pause?
> 
> I will verify the calculation. This looks correct only for single sg transaction.
> 
> Updating xfer_size is added to support drivers which pause the transaction
> and read the status before terminating. 
> Eg. https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/amba-pl011.c

Why you couldn't update the status in tegra_dma_terminate_all()?
Dmitry Osipenko Jan. 30, 2022, 11:23 p.m. UTC | #12
30.01.2022 19:43, Akhil R пишет:
>> 30.01.2022 13:26, Dmitry Osipenko пишет:
>>> 30.01.2022 13:05, Dmitry Osipenko пишет:
>>>> Still nothing prevents interrupt handler to fire during the pause.
>>>>
>>>> What you actually need to do is to disable/enable interrupt. This
>>>> will prevent the interrupt racing and then pause/resume may look like this:
>>>
>>> Although, seems this won't work, unfortunately. I see now that
>>> device_pause() doesn't have might_sleep().
>>>
>>
>> Ah, I see now that the pause/unpause is actually a separate control and doesn't
>> conflict with "start next transfer".
>>
>> So you just need to set/unset the pause under lock. And don't touch
>> tdc->dma_desc. That's it.
>>
>> static int tegra_dma_device_pause(struct dma_chan *dc) {
>>         struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>>         unsigned long flags;
>>         u32 val;
>>
>>         if (!tdc->tdma->chip_data->hw_support_pause)
>>                 return -ENOSYS;
>>
>>         spin_lock_irqsave(&tdc->vc.lock, flags);
>>
>>         val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
>>         val |= TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
>>         tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
>>
>>         spin_unlock_irqrestore(&tdc->vc.lock, flags);
>>
>>         return 0;
>> }
>>
>> static int tegra_dma_device_resume(struct dma_chan *dc) {
>>         struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>>         unsigned long flags;
>>         u32 val;
>>
>>         if (!tdc->tdma->chip_data->hw_support_pause)
>>                 return -ENOSYS;
>>
>>         spin_lock_irqsave(&tdc->vc.lock, flags);
>>
>>         val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
>>         val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
>>         tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
>>
>>         spin_unlock_irqrestore(&tdc->vc.lock, flags);
>>
>>         return 0;
>> }
> 
> The reason I separated out register writes was to conveniently call those
> in dma_start() and terminate_all(). Do you see any issue there?
> The recommended way of terminating a transfer in between is to pause
> it before disabling the channel.

This is a sample code, feel free to adjust it as needed.

> dma_desc could be NULL while these functions are called. pause() or
> resume() is unneeded if there isn't any transfer going on. Moreover,
> if we are to calculate the xfer_size, the check would be mandatory.

For now looks like it should be better to move the xfer_size updating to
other places, like terminate_all() and tx_status().

I also see now that you have
residue_granularity=DMA_RESIDUE_GRANULARITY_BURST, while tx_status()  in
fact uses segment granularity. This needs to be corrected.

You also must add locking to tx_status(), to protect tdc->dma_desc
pointer updates.
Akhil R Jan. 31, 2022, 4:25 a.m. UTC | #13
> 30.01.2022 19:34, Akhil R пишет:
> >> 29.01.2022 19:40, Akhil R пишет:
> >>> +static int tegra_dma_device_pause(struct dma_chan *dc) {
> >>> +     struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> >>> +     unsigned long wcount, flags;
> >>> +     int ret = 0;
> >>> +
> >>> +     if (!tdc->tdma->chip_data->hw_support_pause)
> >>> +             return 0;
> >>
> >> It's wrong to return zero if pause unsupported, please see what
> >> dmaengine_pause() returns.
> >>
> >>> +
> >>> +     spin_lock_irqsave(&tdc->vc.lock, flags);
> >>> +     if (!tdc->dma_desc)
> >>> +             goto out;
> >>> +
> >>> +     ret = tegra_dma_pause(tdc);
> >>> +     if (ret) {
> >>> +             dev_err(tdc2dev(tdc), "DMA pause timed out\n");
> >>> +             goto out;
> >>> +     }
> >>> +
> >>> +     wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
> >>> +     tdc->dma_desc->bytes_xfer +=
> >>> +                     tdc->dma_desc->bytes_req - (wcount * 4);
> >>
> >> Why transfer is accumulated?
> >>
> >> Why do you need to update xfer size at all on pause?
> >
> > I will verify the calculation. This looks correct only for single sg transaction.
> >
> > Updating xfer_size is added to support drivers which pause the
> > transaction and read the status before terminating.
> > Eg.
> 
> Why you couldn't update the status in tegra_dma_terminate_all()?
Is it useful to update the status in terminate_all()? I assume the descriptor
Is freed in vchan_dma_desc_free_list() or am I getting it wrong?

Thanks,
Akhil
Dmitry Osipenko Jan. 31, 2022, 6:42 a.m. UTC | #14
В Mon, 31 Jan 2022 04:25:14 +0000
Akhil R <akhilrajeev@nvidia.com> пишет:

> > 30.01.2022 19:34, Akhil R пишет:  
> > >> 29.01.2022 19:40, Akhil R пишет:  
> > >>> +static int tegra_dma_device_pause(struct dma_chan *dc) {
> > >>> +     struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> > >>> +     unsigned long wcount, flags;
> > >>> +     int ret = 0;
> > >>> +
> > >>> +     if (!tdc->tdma->chip_data->hw_support_pause)
> > >>> +             return 0;  
> > >>
> > >> It's wrong to return zero if pause unsupported, please see what
> > >> dmaengine_pause() returns.
> > >>  
> > >>> +
> > >>> +     spin_lock_irqsave(&tdc->vc.lock, flags);
> > >>> +     if (!tdc->dma_desc)
> > >>> +             goto out;
> > >>> +
> > >>> +     ret = tegra_dma_pause(tdc);
> > >>> +     if (ret) {
> > >>> +             dev_err(tdc2dev(tdc), "DMA pause timed out\n");
> > >>> +             goto out;
> > >>> +     }
> > >>> +
> > >>> +     wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
> > >>> +     tdc->dma_desc->bytes_xfer +=
> > >>> +                     tdc->dma_desc->bytes_req - (wcount * 4);  
> > >>
> > >> Why transfer is accumulated?
> > >>
> > >> Why do you need to update xfer size at all on pause?  
> > >
> > > I will verify the calculation. This looks correct only for single
> > > sg transaction.
> > >
> > > Updating xfer_size is added to support drivers which pause the
> > > transaction and read the status before terminating.
> > > Eg.  
> > 
> > Why you couldn't update the status in tegra_dma_terminate_all()?  
> Is it useful to update the status in terminate_all()? I assume the
> descriptor Is freed in vchan_dma_desc_free_list() or am I getting it
> wrong?

Yes, it's not useful. Then you only need to fix the tx_status() and
don't touch dma_desc on pause.
Akhil R Jan. 31, 2022, 9:09 a.m. UTC | #15
> В Mon, 31 Jan 2022 04:25:14 +0000
> Akhil R <akhilrajeev@nvidia.com> пишет:
> 
> > > 30.01.2022 19:34, Akhil R пишет:
> > > >> 29.01.2022 19:40, Akhil R пишет:
> > > >>> +static int tegra_dma_device_pause(struct dma_chan *dc) {
> > > >>> +     struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> > > >>> +     unsigned long wcount, flags;
> > > >>> +     int ret = 0;
> > > >>> +
> > > >>> +     if (!tdc->tdma->chip_data->hw_support_pause)
> > > >>> +             return 0;
> > > >>
> > > >> It's wrong to return zero if pause unsupported, please see what
> > > >> dmaengine_pause() returns.
> > > >>
> > > >>> +
> > > >>> +     spin_lock_irqsave(&tdc->vc.lock, flags);
> > > >>> +     if (!tdc->dma_desc)
> > > >>> +             goto out;
> > > >>> +
> > > >>> +     ret = tegra_dma_pause(tdc);
> > > >>> +     if (ret) {
> > > >>> +             dev_err(tdc2dev(tdc), "DMA pause timed out\n");
> > > >>> +             goto out;
> > > >>> +     }
> > > >>> +
> > > >>> +     wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
> > > >>> +     tdc->dma_desc->bytes_xfer +=
> > > >>> +                     tdc->dma_desc->bytes_req - (wcount * 4);
> > > >>
> > > >> Why transfer is accumulated?
> > > >>
> > > >> Why do you need to update xfer size at all on pause?
> > > >
> > > > I will verify the calculation. This looks correct only for single
> > > > sg transaction.
> > > >
> > > > Updating xfer_size is added to support drivers which pause the
> > > > transaction and read the status before terminating.
> > > > Eg.
> > >
> > > Why you couldn't update the status in tegra_dma_terminate_all()?
> > Is it useful to update the status in terminate_all()? I assume the
> > descriptor Is freed in vchan_dma_desc_free_list() or am I getting it
> > wrong?
> 
> Yes, it's not useful. Then you only need to fix the tx_status() and
> don't touch dma_desc on pause.
If the bytes_xfer is updated in tx_status(), I suppose 
DMA_RESIDUE_GRANULARITY_BURST can be kept as is, correct?

Thanks,
Akhil
Dmitry Osipenko Jan. 31, 2022, 9:16 a.m. UTC | #16
31.01.2022 12:09, Akhil R пишет:
>> В Mon, 31 Jan 2022 04:25:14 +0000
>> Akhil R <akhilrajeev@nvidia.com> пишет:
>>
>>>> 30.01.2022 19:34, Akhil R пишет:
>>>>>> 29.01.2022 19:40, Akhil R пишет:
>>>>>>> +static int tegra_dma_device_pause(struct dma_chan *dc) {
>>>>>>> +     struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>>>>>>> +     unsigned long wcount, flags;
>>>>>>> +     int ret = 0;
>>>>>>> +
>>>>>>> +     if (!tdc->tdma->chip_data->hw_support_pause)
>>>>>>> +             return 0;
>>>>>>
>>>>>> It's wrong to return zero if pause unsupported, please see what
>>>>>> dmaengine_pause() returns.
>>>>>>
>>>>>>> +
>>>>>>> +     spin_lock_irqsave(&tdc->vc.lock, flags);
>>>>>>> +     if (!tdc->dma_desc)
>>>>>>> +             goto out;
>>>>>>> +
>>>>>>> +     ret = tegra_dma_pause(tdc);
>>>>>>> +     if (ret) {
>>>>>>> +             dev_err(tdc2dev(tdc), "DMA pause timed out\n");
>>>>>>> +             goto out;
>>>>>>> +     }
>>>>>>> +
>>>>>>> +     wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
>>>>>>> +     tdc->dma_desc->bytes_xfer +=
>>>>>>> +                     tdc->dma_desc->bytes_req - (wcount * 4);
>>>>>>
>>>>>> Why transfer is accumulated?
>>>>>>
>>>>>> Why do you need to update xfer size at all on pause?
>>>>>
>>>>> I will verify the calculation. This looks correct only for single
>>>>> sg transaction.
>>>>>
>>>>> Updating xfer_size is added to support drivers which pause the
>>>>> transaction and read the status before terminating.
>>>>> Eg.
>>>>
>>>> Why you couldn't update the status in tegra_dma_terminate_all()?
>>> Is it useful to update the status in terminate_all()? I assume the
>>> descriptor Is freed in vchan_dma_desc_free_list() or am I getting it
>>> wrong?
>>
>> Yes, it's not useful. Then you only need to fix the tx_status() and
>> don't touch dma_desc on pause.
> If the bytes_xfer is updated in tx_status(), I suppose 
> DMA_RESIDUE_GRANULARITY_BURST can be kept as is, correct?

You don't need to update bytes_xfer in tx_status(). Please see Tegra20
DMA driver for the example, which supports GRANULARITY_BURST properly.
Akhil R Jan. 31, 2022, 3:38 p.m. UTC | #17
> 31.01.2022 12:09, Akhil R пишет:
> >> В Mon, 31 Jan 2022 04:25:14 +0000
> >> Akhil R <akhilrajeev@nvidia.com> пишет:
> >>
> >>>> 30.01.2022 19:34, Akhil R пишет:
> >>>>>> 29.01.2022 19:40, Akhil R пишет:
> >>>>>>> +static int tegra_dma_device_pause(struct dma_chan *dc) {
> >>>>>>> +     struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> >>>>>>> +     unsigned long wcount, flags;
> >>>>>>> +     int ret = 0;
> >>>>>>> +
> >>>>>>> +     if (!tdc->tdma->chip_data->hw_support_pause)
> >>>>>>> +             return 0;
> >>>>>>
> >>>>>> It's wrong to return zero if pause unsupported, please see what
> >>>>>> dmaengine_pause() returns.
> >>>>>>
> >>>>>>> +
> >>>>>>> +     spin_lock_irqsave(&tdc->vc.lock, flags);
> >>>>>>> +     if (!tdc->dma_desc)
> >>>>>>> +             goto out;
> >>>>>>> +
> >>>>>>> +     ret = tegra_dma_pause(tdc);
> >>>>>>> +     if (ret) {
> >>>>>>> +             dev_err(tdc2dev(tdc), "DMA pause timed out\n");
> >>>>>>> +             goto out;
> >>>>>>> +     }
> >>>>>>> +
> >>>>>>> +     wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
> >>>>>>> +     tdc->dma_desc->bytes_xfer +=
> >>>>>>> +                     tdc->dma_desc->bytes_req - (wcount * 4);
> >>>>>>
> >>>>>> Why transfer is accumulated?
> >>>>>>
> >>>>>> Why do you need to update xfer size at all on pause?
> >>>>>
> >>>>> I will verify the calculation. This looks correct only for single
> >>>>> sg transaction.
> >>>>>
> >>>>> Updating xfer_size is added to support drivers which pause the
> >>>>> transaction and read the status before terminating.
> >>>>> Eg.
> >>>>
> >>>> Why you couldn't update the status in tegra_dma_terminate_all()?
> >>> Is it useful to update the status in terminate_all()? I assume the
> >>> descriptor Is freed in vchan_dma_desc_free_list() or am I getting it
> >>> wrong?
> >>
> >> Yes, it's not useful. Then you only need to fix the tx_status() and
> >> don't touch dma_desc on pause.
> > If the bytes_xfer is updated in tx_status(), I suppose
> > DMA_RESIDUE_GRANULARITY_BURST can be kept as is, correct?
> 
> You don't need to update bytes_xfer in tx_status(). Please see Tegra20
> DMA driver for the example, which supports GRANULARITY_BURST properly.

Does the below method look good? bytes_xfer is updated on every ISR and in
tx_status(), the wcount is read to calculate the intermittent value. If the transfer
get complete in between, use wcount as 0 to add sg_req.len to bytes_xfer

static int tegra_dma_get_residual(struct tegra_dma_channel *tdc)
{
	unsigned long wcount = 0, status;
	unsigned int bytes_xfer, residual;
	struct tegra_dma_desc *dma_desc = tdc->dma_desc;
	struct tegra_dma_sg_req *sg_req = dma_desc->sg_req;

	/*
	 * Do not read from CHAN_XFER_COUNT if EOC bit is set
	 * as the transfer would have already completed and
	 * the register could have updated for next transfer
	 * in case of cyclic transfers.
	 */
	status = tdc_read(tdc, TEGRA_GPCDMA_CHAN_STATUS);
	if (!(status & TEGRA_GPCDMA_STATUS_ISE_EOC))
		wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);

	bytes_xfer = dma_desc->bytes_xfer +
		     sg_req[dma_desc->sg_idx - 1].len - (wcount * 4);

	residual = dma_desc->bytes_req - (bytes_xfer % dma_desc->bytes_req);

	return residual;
}

static enum dma_status tegra_dma_tx_status( )
{
	....

	spin_lock_irqsave(&tdc->vc.lock, flags);
	...
	} else if (tdc->dma_desc && tdc->dma_desc->vd.tx.cookie == cookie) {
		residual =  tegra_dma_get_residual(tdc);
		dma_set_residue(txstate, residual);
	} else {
		dev_err(tdc2dev(tdc), "cookie %d is not found\n", cookie);
	}
	spin_unlock_irqrestore(&tdc->vc.lock, flags);

	return ret;
}
Dmitry Osipenko Jan. 31, 2022, 4:08 p.m. UTC | #18
31.01.2022 18:38, Akhil R пишет:
> Does the below method look good? bytes_xfer is updated on every ISR and in
> tx_status(), the wcount is read to calculate the intermittent value. If the transfer
> get complete in between, use wcount as 0 to add sg_req.len to bytes_xfer
> 
> static int tegra_dma_get_residual(struct tegra_dma_channel *tdc)
> {
> 	unsigned long wcount = 0, status;
> 	unsigned int bytes_xfer, residual;
> 	struct tegra_dma_desc *dma_desc = tdc->dma_desc;
> 	struct tegra_dma_sg_req *sg_req = dma_desc->sg_req;
> 
> 	/*
> 	 * Do not read from CHAN_XFER_COUNT if EOC bit is set
> 	 * as the transfer would have already completed and
> 	 * the register could have updated for next transfer
> 	 * in case of cyclic transfers.
> 	 */
> 	status = tdc_read(tdc, TEGRA_GPCDMA_CHAN_STATUS);
> 	if (!(status & TEGRA_GPCDMA_STATUS_ISE_EOC))
> 		wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);

You can't read WCOUNT after the STATUS without racing with the STATUS
updates made by h/w. You should read the WCOUNT first and only then
check the STATUS.

You should also check whether T20 tegra_dma_sg_bytes_xferred()
workarounds apply to newer h/w. I see that the h/w base hasn't changed
much since T20.

Otherwise looks okay.
Akhil R Feb. 1, 2022, 12:05 p.m. UTC | #19
> 31.01.2022 18:38, Akhil R пишет:
> > Does the below method look good? bytes_xfer is updated on every ISR and in
> > tx_status(), the wcount is read to calculate the intermittent value. If the
> transfer
> > get complete in between, use wcount as 0 to add sg_req.len to bytes_xfer
> >
> > static int tegra_dma_get_residual(struct tegra_dma_channel *tdc)
> > {
> >       unsigned long wcount = 0, status;
> >       unsigned int bytes_xfer, residual;
> >       struct tegra_dma_desc *dma_desc = tdc->dma_desc;
> >       struct tegra_dma_sg_req *sg_req = dma_desc->sg_req;
> >
> >       /*
> >        * Do not read from CHAN_XFER_COUNT if EOC bit is set
> >        * as the transfer would have already completed and
> >        * the register could have updated for next transfer
> >        * in case of cyclic transfers.
> >        */
> >       status = tdc_read(tdc, TEGRA_GPCDMA_CHAN_STATUS);
> >       if (!(status & TEGRA_GPCDMA_STATUS_ISE_EOC))
> >               wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
> 
> You can't read WCOUNT after the STATUS without racing with the STATUS
> updates made by h/w. You should read the WCOUNT first and only then
> check the STATUS.
> 
> You should also check whether T20 tegra_dma_sg_bytes_xferred()
> workarounds apply to newer h/w. I see that the h/w base hasn't changed
> much since T20.
The calculation in T20 driver is not applicable here. The register shows the
actual number of words remaining to be transferred as far as I understand.

Thanks,
Akhil
Dmitry Osipenko Feb. 1, 2022, 1:06 p.m. UTC | #20
01.02.2022 15:05, Akhil R пишет:
>> 31.01.2022 18:38, Akhil R пишет:
>>> Does the below method look good? bytes_xfer is updated on every ISR and in
>>> tx_status(), the wcount is read to calculate the intermittent value. If the
>> transfer
>>> get complete in between, use wcount as 0 to add sg_req.len to bytes_xfer
>>>
>>> static int tegra_dma_get_residual(struct tegra_dma_channel *tdc)
>>> {
>>>       unsigned long wcount = 0, status;
>>>       unsigned int bytes_xfer, residual;
>>>       struct tegra_dma_desc *dma_desc = tdc->dma_desc;
>>>       struct tegra_dma_sg_req *sg_req = dma_desc->sg_req;
>>>
>>>       /*
>>>        * Do not read from CHAN_XFER_COUNT if EOC bit is set
>>>        * as the transfer would have already completed and
>>>        * the register could have updated for next transfer
>>>        * in case of cyclic transfers.
>>>        */
>>>       status = tdc_read(tdc, TEGRA_GPCDMA_CHAN_STATUS);
>>>       if (!(status & TEGRA_GPCDMA_STATUS_ISE_EOC))
>>>               wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
>>
>> You can't read WCOUNT after the STATUS without racing with the STATUS
>> updates made by h/w. You should read the WCOUNT first and only then
>> check the STATUS.
>>
>> You should also check whether T20 tegra_dma_sg_bytes_xferred()
>> workarounds apply to newer h/w. I see that the h/w base hasn't changed
>> much since T20.
> The calculation in T20 driver is not applicable here. The register shows the
> actual number of words remaining to be transferred as far as I understand.

If downstream kernel DMA driver doesn't have any special quirks, then
likely that they are indeed unneeded.
diff mbox series

Patch

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 6bcdb4e..dbe7664 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -629,6 +629,17 @@  config TXX9_DMAC
 	  Support the TXx9 SoC internal DMA controller.  This can be
 	  integrated in chips such as the Toshiba TX4927/38/39.
 
+config TEGRA186_GPC_DMA
+	tristate "NVIDIA Tegra GPC DMA support"
+	depends on ARCH_TEGRA || COMPILE_TEST
+	select DMA_ENGINE
+	help
+	  Support for the NVIDIA Tegra General Purpose Central DMA controller.
+	  The DMA controller has multiple DMA channels which can be configured
+	  for different peripherals like UART, SPI, etc which are on APB bus.
+	  This DMA controller transfers data from memory to peripheral FIFO
+	  or vice versa. It also supports memory to memory data transfer.
+
 config TEGRA20_APB_DMA
 	tristate "NVIDIA Tegra20 APB DMA support"
 	depends on ARCH_TEGRA || COMPILE_TEST
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index 616d926..2f1b87f 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -72,6 +72,7 @@  obj-$(CONFIG_STM32_MDMA) += stm32-mdma.o
 obj-$(CONFIG_SPRD_DMA) += sprd-dma.o
 obj-$(CONFIG_S3C24XX_DMAC) += s3c24xx-dma.o
 obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
+obj-$(CONFIG_TEGRA186_GPC_DMA) += tegra186-gpc-dma.o
 obj-$(CONFIG_TEGRA20_APB_DMA) += tegra20-apb-dma.o
 obj-$(CONFIG_TEGRA210_ADMA) += tegra210-adma.o
 obj-$(CONFIG_TIMB_DMA) += timb_dma.o
diff --git a/drivers/dma/tegra186-gpc-dma.c b/drivers/dma/tegra186-gpc-dma.c
new file mode 100644
index 0000000..4e477da
--- /dev/null
+++ b/drivers/dma/tegra186-gpc-dma.c
@@ -0,0 +1,1488 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * DMA driver for NVIDIA Tegra186 and Tegra194 GPC DMA controller.
+ *
+ * Copyright (c) 2014 - 2022, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/iommu.h>
+#include <linux/iopoll.h>
+#include <linux/minmax.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+#include <linux/version.h>
+#include <dt-bindings/memory/tegra186-mc.h>
+#include "virt-dma.h"
+
+/* CSR register */
+#define TEGRA_GPCDMA_CHAN_CSR			0x00
+#define TEGRA_GPCDMA_CSR_ENB			BIT(31)
+#define TEGRA_GPCDMA_CSR_IE_EOC			BIT(30)
+#define TEGRA_GPCDMA_CSR_ONCE			BIT(27)
+
+#define TEGRA_GPCDMA_CSR_FC_MODE		GENMASK(25, 24)
+#define TEGRA_GPCDMA_CSR_FC_MODE_NO_MMIO	\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_FC_MODE, 0)
+#define TEGRA_GPCDMA_CSR_FC_MODE_ONE_MMIO	\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_FC_MODE, 1)
+#define TEGRA_GPCDMA_CSR_FC_MODE_TWO_MMIO	\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_FC_MODE, 2)
+#define TEGRA_GPCDMA_CSR_FC_MODE_FOUR_MMIO	\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_FC_MODE, 3)
+
+#define TEGRA_GPCDMA_CSR_DMA			GENMASK(23, 21)
+#define TEGRA_GPCDMA_CSR_DMA_IO2MEM_NO_FC	\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_DMA, 0)
+#define TEGRA_GPCDMA_CSR_DMA_IO2MEM_FC		\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_DMA, 1)
+#define TEGRA_GPCDMA_CSR_DMA_MEM2IO_NO_FC	\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_DMA, 2)
+#define TEGRA_GPCDMA_CSR_DMA_MEM2IO_FC		\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_DMA, 3)
+#define TEGRA_GPCDMA_CSR_DMA_MEM2MEM		\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_DMA, 4)
+#define TEGRA_GPCDMA_CSR_DMA_FIXED_PAT		\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_DMA, 6)
+
+#define TEGRA_GPCDMA_CSR_REQ_SEL_MASK		GENMASK(20, 16)
+#define TEGRA_GPCDMA_CSR_REQ_SEL_UNUSED		\
+					FIELD_PREP(TEGRA_GPCDMA_CSR_REQ_SEL_MASK, 4)
+#define TEGRA_GPCDMA_CSR_IRQ_MASK		BIT(15)
+#define TEGRA_GPCDMA_CSR_WEIGHT			GENMASK(13, 10)
+
+/* STATUS register */
+#define TEGRA_GPCDMA_CHAN_STATUS		0x004
+#define TEGRA_GPCDMA_STATUS_BUSY		BIT(31)
+#define TEGRA_GPCDMA_STATUS_ISE_EOC		BIT(30)
+#define TEGRA_GPCDMA_STATUS_PING_PONG		BIT(28)
+#define TEGRA_GPCDMA_STATUS_DMA_ACTIVITY	BIT(27)
+#define TEGRA_GPCDMA_STATUS_CHANNEL_PAUSE	BIT(26)
+#define TEGRA_GPCDMA_STATUS_CHANNEL_RX		BIT(25)
+#define TEGRA_GPCDMA_STATUS_CHANNEL_TX		BIT(24)
+#define TEGRA_GPCDMA_STATUS_IRQ_INTR_STA	BIT(23)
+#define TEGRA_GPCDMA_STATUS_IRQ_STA		BIT(21)
+#define TEGRA_GPCDMA_STATUS_IRQ_TRIG_STA	BIT(20)
+
+#define TEGRA_GPCDMA_CHAN_CSRE			0x008
+#define TEGRA_GPCDMA_CHAN_CSRE_PAUSE		BIT(31)
+
+/* Source address */
+#define TEGRA_GPCDMA_CHAN_SRC_PTR		0x00C
+
+/* Destination address */
+#define TEGRA_GPCDMA_CHAN_DST_PTR		0x010
+
+/* High address pointer */
+#define TEGRA_GPCDMA_CHAN_HIGH_ADDR_PTR		0x014
+#define TEGRA_GPCDMA_HIGH_ADDR_SRC_PTR		GENMASK(7, 0)
+#define TEGRA_GPCDMA_HIGH_ADDR_DST_PTR		GENMASK(23, 16)
+
+/* MC sequence register */
+#define TEGRA_GPCDMA_CHAN_MCSEQ			0x18
+#define TEGRA_GPCDMA_MCSEQ_DATA_SWAP		BIT(31)
+#define TEGRA_GPCDMA_MCSEQ_REQ_COUNT		GENMASK(30, 25)
+#define TEGRA_GPCDMA_MCSEQ_BURST		GENMASK(24, 23)
+#define TEGRA_GPCDMA_MCSEQ_BURST_2		\
+					FIELD_PREP(TEGRA_GPCDMA_MCSEQ_BURST, 0)
+#define TEGRA_GPCDMA_MCSEQ_BURST_16		\
+					FIELD_PREP(TEGRA_GPCDMA_MCSEQ_BURST, 3)
+#define TEGRA_GPCDMA_MCSEQ_WRAP1		GENMASK(22, 20)
+#define TEGRA_GPCDMA_MCSEQ_WRAP0		GENMASK(19, 17)
+#define TEGRA_GPCDMA_MCSEQ_WRAP_NONE		0
+
+#define TEGRA_GPCDMA_MCSEQ_STREAM_ID1_MASK	GENMASK(13, 7)
+#define TEGRA_GPCDMA_MCSEQ_STREAM_ID0_MASK	GENMASK(6, 0)
+
+/* MMIO sequence register */
+#define TEGRA_GPCDMA_CHAN_MMIOSEQ			0x01c
+#define TEGRA_GPCDMA_MMIOSEQ_DBL_BUF		BIT(31)
+#define TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH		GENMASK(30, 28)
+#define TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH_8	\
+					FIELD_PREP(TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH, 0)
+#define TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH_16	\
+					FIELD_PREP(TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH, 1)
+#define TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH_32	\
+					FIELD_PREP(TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH, 2)
+#define TEGRA_GPCDMA_MMIOSEQ_DATA_SWAP		BIT(27)
+#define TEGRA_GPCDMA_MMIOSEQ_BURST_SHIFT	23
+#define TEGRA_GPCDMA_MMIOSEQ_BURST_MIN		2U
+#define TEGRA_GPCDMA_MMIOSEQ_BURST_MAX		32U
+#define TEGRA_GPCDMA_MMIOSEQ_BURST(bs)	\
+		(GENMASK((fls(bs) - 2), 0) << TEGRA_GPCDMA_MMIOSEQ_BURST_SHIFT)
+#define TEGRA_GPCDMA_MMIOSEQ_MASTER_ID		GENMASK(22, 19)
+#define TEGRA_GPCDMA_MMIOSEQ_WRAP_WORD		GENMASK(18, 16)
+#define TEGRA_GPCDMA_MMIOSEQ_MMIO_PROT		GENMASK(8, 7)
+
+/* Channel WCOUNT */
+#define TEGRA_GPCDMA_CHAN_WCOUNT		0x20
+
+/* Transfer count */
+#define TEGRA_GPCDMA_CHAN_XFER_COUNT		0x24
+
+/* DMA byte count status */
+#define TEGRA_GPCDMA_CHAN_DMA_BYTE_STATUS	0x28
+
+/* Error Status Register */
+#define TEGRA_GPCDMA_CHAN_ERR_STATUS		0x30
+#define TEGRA_GPCDMA_CHAN_ERR_TYPE_SHIFT	8
+#define TEGRA_GPCDMA_CHAN_ERR_TYPE_MASK	0xF
+#define TEGRA_GPCDMA_CHAN_ERR_TYPE(err)	(			\
+		((err) >> TEGRA_GPCDMA_CHAN_ERR_TYPE_SHIFT) &	\
+		TEGRA_GPCDMA_CHAN_ERR_TYPE_MASK)
+#define TEGRA_DMA_BM_FIFO_FULL_ERR		0xF
+#define TEGRA_DMA_PERIPH_FIFO_FULL_ERR		0xE
+#define TEGRA_DMA_PERIPH_ID_ERR			0xD
+#define TEGRA_DMA_STREAM_ID_ERR			0xC
+#define TEGRA_DMA_MC_SLAVE_ERR			0xB
+#define TEGRA_DMA_MMIO_SLAVE_ERR		0xA
+
+/* Fixed Pattern */
+#define TEGRA_GPCDMA_CHAN_FIXED_PATTERN		0x34
+
+#define TEGRA_GPCDMA_CHAN_TZ			0x38
+#define TEGRA_GPCDMA_CHAN_TZ_MMIO_PROT_1	BIT(0)
+#define TEGRA_GPCDMA_CHAN_TZ_MC_PROT_1		BIT(1)
+
+#define TEGRA_GPCDMA_CHAN_SPARE			0x3c
+#define TEGRA_GPCDMA_CHAN_SPARE_EN_LEGACY_FC	BIT(16)
+
+/*
+ * If any burst is in flight and DMA paused then this is the time to complete
+ * on-flight burst and update DMA status register.
+ */
+#define TEGRA_GPCDMA_BURST_COMPLETE_TIME	20
+#define TEGRA_GPCDMA_BURST_COMPLETION_TIMEOUT	100
+
+/* Channel base address offset from GPCDMA base address */
+#define TEGRA_GPCDMA_CHANNEL_BASE_ADD_OFFSET	0x20000
+
+struct tegra_dma;
+
+/*
+ * tegra_dma_chip_data Tegra chip specific DMA data
+ * @nr_channels: Number of channels available in the controller.
+ * @channel_reg_size: Channel register size.
+ * @max_dma_count: Maximum DMA transfer count supported by DMA controller.
+ * @hw_support_pause: DMA HW engine support pause of the channel.
+ */
+struct tegra_dma_chip_data {
+	unsigned int nr_channels;
+	unsigned int channel_reg_size;
+	unsigned int max_dma_count;
+	bool hw_support_pause;
+};
+
+/* DMA channel registers */
+struct tegra_dma_channel_regs {
+	unsigned long csr;
+	unsigned long src_ptr;
+	unsigned long dst_ptr;
+	unsigned long high_addr_ptr;
+	unsigned long mc_seq;
+	unsigned long mmio_seq;
+	unsigned long wcount;
+	unsigned long fixed_pattern;
+};
+
+/*
+ * tegra_dma_sg_req: Dma request details to configure hardware. This
+ * contains the details for one transfer to configure DMA hw.
+ * The client's request for data transfer can be broken into multiple
+ * sub-transfer as per requester details and hw support. This sub transfer
+ * get added as an array in Tegra DMA desc which manages the transfer details.
+ */
+struct tegra_dma_sg_req {
+	unsigned int len;
+	struct tegra_dma_channel_regs ch_regs;
+};
+
+/*
+ * tegra_dma_desc: Tegra DMA descriptors which uses virt_dma_desc to
+ * manage client request and keep track of transfer status, callbacks
+ * and request counts etc.
+ */
+struct tegra_dma_desc {
+	struct virt_dma_desc vd;
+	unsigned int bytes_req;
+	unsigned int bytes_xfer;
+	unsigned int sg_idx;
+	unsigned int sg_count;
+	bool cyclic;
+	struct tegra_dma_channel *tdc;
+	struct tegra_dma_sg_req sg_req[];
+};
+
+/*
+ * tegra_dma_channel: Channel specific information
+ */
+struct tegra_dma_channel {
+	struct virt_dma_chan vc;
+	struct tegra_dma_desc *dma_desc;
+	char name[30];
+	bool config_init;
+	int id;
+	int irq;
+	unsigned int stream_id;
+	unsigned long chan_base_offset;
+	struct tegra_dma *tdma;
+	int slave_id;
+	enum dma_transfer_direction sid_dir;
+	struct dma_slave_config dma_sconfig;
+};
+
+/*
+ * tegra_dma: Tegra DMA specific information
+ */
+struct tegra_dma {
+	struct dma_device dma_dev;
+	struct device *dev;
+	void __iomem *base_addr;
+	const struct tegra_dma_chip_data *chip_data;
+	struct reset_control *rst;
+	unsigned long sid_m2d_reserved;
+	unsigned long sid_d2m_reserved;
+	struct tegra_dma_channel channels[];
+};
+
+static inline void tdc_write(struct tegra_dma_channel *tdc,
+			     u32 reg, u32 val)
+{
+	writel_relaxed(val, tdc->tdma->base_addr + tdc->chan_base_offset + reg);
+}
+
+static inline u32 tdc_read(struct tegra_dma_channel *tdc, u32 reg)
+{
+	return readl_relaxed(tdc->tdma->base_addr + tdc->chan_base_offset + reg);
+}
+
+static inline struct tegra_dma_channel *to_tegra_dma_chan(struct dma_chan *dc)
+{
+	return container_of(dc, struct tegra_dma_channel, vc.chan);
+}
+
+static inline struct tegra_dma_desc *vd_to_tegra_dma_desc(struct virt_dma_desc *vd)
+{
+	return container_of(vd, struct tegra_dma_desc, vd);
+}
+
+static inline struct device *tdc2dev(struct tegra_dma_channel *tdc)
+{
+	return tdc->vc.chan.device->dev;
+}
+
+static void tegra_dma_dump_chan_regs(struct tegra_dma_channel *tdc)
+{
+	dev_dbg(tdc2dev(tdc), "DMA Channel %d name %s register dump:\n",
+		tdc->id, tdc->name);
+	dev_dbg(tdc2dev(tdc), "CSR %x STA %x CSRE %x SRC %x DST %x\n",
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSR),
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_STATUS),
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE),
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_SRC_PTR),
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_DST_PTR)
+	);
+	dev_dbg(tdc2dev(tdc), "MCSEQ %x IOSEQ %x WCNT %x XFER %x BSTA %x\n",
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_MCSEQ),
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_MMIOSEQ),
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_WCOUNT),
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT),
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_DMA_BYTE_STATUS)
+	);
+	dev_dbg(tdc2dev(tdc), "DMA ERR_STA %x\n",
+		tdc_read(tdc, TEGRA_GPCDMA_CHAN_ERR_STATUS));
+}
+
+static int tegra_dma_sid_reserve(struct tegra_dma_channel *tdc,
+				 enum dma_transfer_direction direction)
+{
+	struct tegra_dma *tdma = tdc->tdma;
+	unsigned int sid = tdc->slave_id;
+
+	if (!is_slave_direction(direction))
+		return 0;
+
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		if (test_and_set_bit(sid, &tdma->sid_m2d_reserved)) {
+			dev_err(tdma->dev, "slave id already in use\n");
+			return -EINVAL;
+		}
+		break;
+	case DMA_DEV_TO_MEM:
+		if (test_and_set_bit(sid, &tdma->sid_d2m_reserved)) {
+			dev_err(tdma->dev, "slave id already in use\n");
+			return -EINVAL;
+		}
+		break;
+	default:
+		break;
+	}
+
+	tdc->sid_dir = direction;
+
+	return 0;
+}
+
+static void tegra_dma_sid_free(struct tegra_dma_channel *tdc)
+{
+	struct tegra_dma *tdma = tdc->tdma;
+	unsigned int sid = tdc->slave_id;
+
+	switch (tdc->sid_dir) {
+	case DMA_MEM_TO_DEV:
+		clear_bit(sid,  &tdma->sid_m2d_reserved);
+		break;
+	case DMA_DEV_TO_MEM:
+		clear_bit(sid,  &tdma->sid_d2m_reserved);
+		break;
+	default:
+		break;
+	}
+
+	tdc->sid_dir = DMA_TRANS_NONE;
+}
+
+static void tegra_dma_desc_free(struct virt_dma_desc *vd)
+{
+	kfree(container_of(vd, struct tegra_dma_desc, vd));
+}
+
+static int tegra_dma_slave_config(struct dma_chan *dc,
+				  struct dma_slave_config *sconfig)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+
+	memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig));
+	tdc->config_init = true;
+
+	return 0;
+}
+
+static int tegra_dma_pause(struct tegra_dma_channel *tdc)
+{
+	int ret;
+	u32 val;
+
+	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
+	val |= TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
+
+	/* Wait until busy bit is de-asserted */
+	ret = readl_relaxed_poll_timeout_atomic(tdc->tdma->base_addr +
+			tdc->chan_base_offset + TEGRA_GPCDMA_CHAN_STATUS,
+			val,
+			!(val & TEGRA_GPCDMA_STATUS_BUSY),
+			TEGRA_GPCDMA_BURST_COMPLETE_TIME,
+			TEGRA_GPCDMA_BURST_COMPLETION_TIMEOUT);
+
+	return ret;
+}
+
+static int tegra_dma_device_pause(struct dma_chan *dc)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	unsigned long wcount, flags;
+	int ret = 0;
+
+	if (!tdc->tdma->chip_data->hw_support_pause)
+		return 0;
+
+	spin_lock_irqsave(&tdc->vc.lock, flags);
+	if (!tdc->dma_desc)
+		goto out;
+
+	ret = tegra_dma_pause(tdc);
+	if (ret) {
+		dev_err(tdc2dev(tdc), "DMA pause timed out\n");
+		goto out;
+	}
+
+	wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_XFER_COUNT);
+	tdc->dma_desc->bytes_xfer +=
+			tdc->dma_desc->bytes_req - (wcount * 4);
+
+out:
+	spin_unlock_irqrestore(&tdc->vc.lock, flags);
+
+	return ret;
+}
+
+static void tegra_dma_resume(struct tegra_dma_channel *tdc)
+{
+	u32 val;
+
+	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
+	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
+}
+
+static int tegra_dma_device_resume(struct dma_chan *dc)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	unsigned long flags;
+
+	if (!tdc->tdma->chip_data->hw_support_pause)
+		return 0;
+
+	spin_lock_irqsave(&tdc->vc.lock, flags);
+	if (!tdc->dma_desc)
+		goto out;
+
+	tegra_dma_resume(tdc);
+
+out:
+	spin_unlock_irqrestore(&tdc->vc.lock, flags);
+
+	return 0;
+}
+
+static void tegra_dma_stop(struct tegra_dma_channel *tdc)
+{
+	u32 csr, status;
+
+	csr = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSR);
+
+	/* Disable interrupts */
+	csr &= ~TEGRA_GPCDMA_CSR_IE_EOC;
+
+	/* Disable DMA */
+	csr &= ~TEGRA_GPCDMA_CSR_ENB;
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSR, csr);
+
+	/* Clear interrupt status if it is there */
+	status = tdc_read(tdc, TEGRA_GPCDMA_CHAN_STATUS);
+	if (status & TEGRA_GPCDMA_STATUS_ISE_EOC) {
+		dev_dbg(tdc2dev(tdc), "%s():clearing interrupt\n", __func__);
+		tdc_write(tdc, TEGRA_GPCDMA_CHAN_STATUS, status);
+	}
+}
+
+static void tegra_dma_configure_next_sg(struct tegra_dma_channel *tdc)
+{
+	struct tegra_dma_desc *dma_desc = tdc->dma_desc;
+	struct tegra_dma_channel_regs *ch_regs;
+	int err;
+	u32 val;
+
+	/* Configure next transfer immediately after DMA is busy */
+	err = readl_relaxed_poll_timeout_atomic(tdc->tdma->base_addr +
+			tdc->chan_base_offset + TEGRA_GPCDMA_CHAN_STATUS,
+			val,
+			(val & TEGRA_GPCDMA_STATUS_BUSY), 0,
+			TEGRA_GPCDMA_BURST_COMPLETION_TIMEOUT);
+	if (err)
+		return;
+
+	ch_regs = &dma_desc->sg_req[dma_desc->sg_idx].ch_regs;
+
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_WCOUNT, ch_regs->wcount);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_SRC_PTR, ch_regs->src_ptr);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_DST_PTR, ch_regs->dst_ptr);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_HIGH_ADDR_PTR, ch_regs->high_addr_ptr);
+
+	/* Start DMA */
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSR,
+		  ch_regs->csr | TEGRA_GPCDMA_CSR_ENB);
+
+	dma_desc->sg_idx++;
+
+	/* Reset the sg index for cyclic transfers */
+	if (dma_desc->sg_idx == dma_desc->sg_count)
+		dma_desc->sg_idx = 0;
+}
+
+static void tegra_dma_start(struct tegra_dma_channel *tdc)
+{
+	struct tegra_dma_desc *dma_desc = tdc->dma_desc;
+	struct tegra_dma_channel_regs *ch_regs;
+	struct virt_dma_desc *vdesc;
+
+	if (!dma_desc) {
+		vdesc = vchan_next_desc(&tdc->vc);
+		if (!vdesc)
+			return;
+
+		dma_desc = vd_to_tegra_dma_desc(vdesc);
+		list_del(&vdesc->node);
+		dma_desc->tdc = tdc;
+		tdc->dma_desc = dma_desc;
+
+		tegra_dma_resume(tdc);
+	}
+
+	ch_regs = &dma_desc->sg_req[dma_desc->sg_idx].ch_regs;
+
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_WCOUNT, ch_regs->wcount);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSR, 0);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_SRC_PTR, ch_regs->src_ptr);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_DST_PTR, ch_regs->dst_ptr);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_HIGH_ADDR_PTR, ch_regs->high_addr_ptr);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_FIXED_PATTERN, ch_regs->fixed_pattern);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_MMIOSEQ, ch_regs->mmio_seq);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_MCSEQ, ch_regs->mc_seq);
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSR, ch_regs->csr);
+
+	/* Start DMA */
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSR,
+		  ch_regs->csr | TEGRA_GPCDMA_CSR_ENB);
+
+	dma_desc->sg_idx++;
+}
+
+static void tegra_dma_xfer_complete(struct tegra_dma_channel *tdc)
+{
+	vchan_cookie_complete(&tdc->dma_desc->vd);
+
+	tegra_dma_sid_free(tdc);
+	tdc->dma_desc = NULL;
+}
+
+static void tegra_dma_chan_decode_error(struct tegra_dma_channel *tdc,
+					unsigned int err_status)
+{
+	switch (TEGRA_GPCDMA_CHAN_ERR_TYPE(err_status)) {
+	case TEGRA_DMA_BM_FIFO_FULL_ERR:
+		dev_err(tdc->tdma->dev,
+			"GPCDMA CH%d bm fifo full\n", tdc->id);
+		break;
+
+	case TEGRA_DMA_PERIPH_FIFO_FULL_ERR:
+		dev_err(tdc->tdma->dev,
+			"GPCDMA CH%d peripheral fifo full\n", tdc->id);
+		break;
+
+	case TEGRA_DMA_PERIPH_ID_ERR:
+		dev_err(tdc->tdma->dev,
+			"GPCDMA CH%d illegal peripheral id\n", tdc->id);
+		break;
+
+	case TEGRA_DMA_STREAM_ID_ERR:
+		dev_err(tdc->tdma->dev,
+			"GPCDMA CH%d illegal stream id\n", tdc->id);
+		break;
+
+	case TEGRA_DMA_MC_SLAVE_ERR:
+		dev_err(tdc->tdma->dev,
+			"GPCDMA CH%d mc slave error\n", tdc->id);
+		break;
+
+	case TEGRA_DMA_MMIO_SLAVE_ERR:
+		dev_err(tdc->tdma->dev,
+			"GPCDMA CH%d mmio slave error\n", tdc->id);
+		break;
+
+	default:
+		dev_err(tdc->tdma->dev,
+			"GPCDMA CH%d security violation %x\n", tdc->id,
+			err_status);
+	}
+}
+
+static irqreturn_t tegra_dma_isr(int irq, void *dev_id)
+{
+	struct tegra_dma_channel *tdc = dev_id;
+	struct tegra_dma_desc *dma_desc = tdc->dma_desc;
+	struct tegra_dma_sg_req *sg_req;
+	u32 status;
+
+	/* Check channel error status register */
+	status = tdc_read(tdc, TEGRA_GPCDMA_CHAN_ERR_STATUS);
+	if (status) {
+		tegra_dma_chan_decode_error(tdc, status);
+		tegra_dma_dump_chan_regs(tdc);
+		tdc_write(tdc, TEGRA_GPCDMA_CHAN_ERR_STATUS, 0xFFFFFFFF);
+	}
+
+	spin_lock(&tdc->vc.lock);
+	status = tdc_read(tdc, TEGRA_GPCDMA_CHAN_STATUS);
+	if (!(status & TEGRA_GPCDMA_STATUS_ISE_EOC))
+		goto irq_done;
+
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_STATUS,
+		  TEGRA_GPCDMA_STATUS_ISE_EOC);
+
+	if (!dma_desc)
+		goto irq_done;
+
+	sg_req = dma_desc->sg_req;
+	dma_desc->bytes_xfer += sg_req[dma_desc->sg_idx - 1].len;
+
+	if (dma_desc->sg_idx == dma_desc->sg_count) {
+		tegra_dma_xfer_complete(tdc);
+	} else if (dma_desc->cyclic) {
+		vchan_cyclic_callback(&dma_desc->vd);
+		tegra_dma_configure_next_sg(tdc);
+	} else {
+		tegra_dma_start(tdc);
+	}
+
+irq_done:
+	spin_unlock(&tdc->vc.lock);
+	return IRQ_HANDLED;
+}
+
+static void tegra_dma_issue_pending(struct dma_chan *dc)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	unsigned long flags;
+
+	if (tdc->dma_desc)
+		return;
+
+	spin_lock_irqsave(&tdc->vc.lock, flags);
+	if (vchan_issue_pending(&tdc->vc))
+		tegra_dma_start(tdc);
+
+	/*
+	 * For cyclic dma transfers, program the second
+	 * transfer parameters as soon as the first dma
+	 * transfer is started inorder for the dma
+	 * controller to trigger the second transfer
+	 * with the correct parameters.
+	 */
+	if (tdc->dma_desc && tdc->dma_desc->cyclic)
+		tegra_dma_configure_next_sg(tdc);
+
+	spin_unlock_irqrestore(&tdc->vc.lock, flags);
+}
+
+static int tegra_dma_stop_client(struct tegra_dma_channel *tdc)
+{
+	int ret;
+	unsigned long status;
+	u32 csr = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSR);
+
+	/*
+	 * Change the client associated with the DMA channel
+	 * to stop DMA engine from starting any more bursts for
+	 * the given client and wait for in flight bursts to complete
+	 */
+	csr &= ~(TEGRA_GPCDMA_CSR_REQ_SEL_MASK);
+	csr |= TEGRA_GPCDMA_CSR_REQ_SEL_UNUSED;
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSR, csr);
+
+	/* Wait for in flight data transfer to finish */
+	udelay(TEGRA_GPCDMA_BURST_COMPLETE_TIME);
+
+	/* If TX/RX path is still active wait till it becomes
+	 * inactive
+	 */
+
+	ret = readl_relaxed_poll_timeout_atomic(tdc->tdma->base_addr +
+				tdc->chan_base_offset +
+				TEGRA_GPCDMA_CHAN_STATUS,
+				status,
+				!(status & (TEGRA_GPCDMA_STATUS_CHANNEL_TX |
+				TEGRA_GPCDMA_STATUS_CHANNEL_RX)),
+				5,
+				TEGRA_GPCDMA_BURST_COMPLETION_TIMEOUT);
+	if (ret) {
+		dev_err(tdc2dev(tdc), "Timeout waiting for DMA burst completion!\n");
+		tegra_dma_dump_chan_regs(tdc);
+	}
+
+	return ret;
+}
+
+static int tegra_dma_terminate_all(struct dma_chan *dc)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	unsigned long flags;
+	LIST_HEAD(head);
+	int err;
+
+	spin_lock_irqsave(&tdc->vc.lock, flags);
+
+	if (tdc->dma_desc) {
+		err = tdc->tdma->chip_data->hw_support_pause ?
+		      tegra_dma_pause(tdc) :
+		      tegra_dma_stop_client(tdc);
+		if (err) {
+			spin_unlock_irqrestore(&tdc->vc.lock, flags);
+			return err;
+		}
+
+		tegra_dma_stop(tdc);
+		tdc->dma_desc = NULL;
+	}
+
+	tegra_dma_sid_free(tdc);
+	vchan_get_all_descriptors(&tdc->vc, &head);
+	spin_unlock_irqrestore(&tdc->vc.lock, flags);
+
+	vchan_dma_desc_free_list(&tdc->vc, &head);
+
+	return 0;
+}
+
+static enum dma_status tegra_dma_tx_status(struct dma_chan *dc,
+					   dma_cookie_t cookie,
+					   struct dma_tx_state *txstate)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	struct tegra_dma_desc *dma_desc;
+	struct virt_dma_desc *vd;
+	unsigned int residual;
+	enum dma_status ret;
+
+	ret = dma_cookie_status(dc, cookie, txstate);
+	if (ret == DMA_COMPLETE)
+		return ret;
+
+	vd = vchan_find_desc(&tdc->vc, cookie);
+	if (vd) {
+		dma_desc = vd_to_tegra_dma_desc(vd);
+		residual = dma_desc->bytes_req;
+		dma_set_residue(txstate, residual);
+	} else if (tdc->dma_desc && tdc->dma_desc->vd.tx.cookie == cookie) {
+		dma_desc = tdc->dma_desc;
+		residual =  dma_desc->bytes_req -
+				(dma_desc->bytes_xfer %
+				dma_desc->bytes_req);
+		dma_set_residue(txstate, residual);
+	} else {
+		dev_err(tdc2dev(tdc), "cookie %d is not found\n", cookie);
+	}
+
+	return ret;
+}
+
+static inline int get_bus_width(struct tegra_dma_channel *tdc,
+				enum dma_slave_buswidth slave_bw)
+{
+	switch (slave_bw) {
+	case DMA_SLAVE_BUSWIDTH_1_BYTE:
+		return TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH_8;
+	case DMA_SLAVE_BUSWIDTH_2_BYTES:
+		return TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH_16;
+	case DMA_SLAVE_BUSWIDTH_4_BYTES:
+		return TEGRA_GPCDMA_MMIOSEQ_BUS_WIDTH_32;
+	default:
+		dev_err(tdc2dev(tdc), "given slave bus width is not supported\n");
+		return -EINVAL;
+	}
+}
+
+static unsigned int get_burst_size(struct tegra_dma_channel *tdc,
+				   u32 burst_size, enum dma_slave_buswidth slave_bw,
+				   int len)
+{
+	unsigned int burst_mmio_width, burst_byte;
+
+	/*
+	 * burst_size from client is in terms of the bus_width.
+	 * convert that into words.
+	 * If burst_size is not specified from client, then use
+	 * len to calculate the optimum burst size
+	 */
+	burst_byte = burst_size ? burst_size * slave_bw : len;
+	burst_mmio_width = burst_byte / 4;
+
+	if (burst_mmio_width < TEGRA_GPCDMA_MMIOSEQ_BURST_MIN)
+		return 0;
+
+	burst_mmio_width = min(burst_mmio_width, TEGRA_GPCDMA_MMIOSEQ_BURST_MAX);
+
+	return TEGRA_GPCDMA_MMIOSEQ_BURST(burst_mmio_width);
+}
+
+static int get_transfer_param(struct tegra_dma_channel *tdc,
+			      enum dma_transfer_direction direction,
+			      unsigned long *apb_addr,
+			      unsigned long *mmio_seq,
+			      unsigned long *csr,
+			      unsigned int *burst_size,
+			      enum dma_slave_buswidth *slave_bw)
+{
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		*apb_addr = tdc->dma_sconfig.dst_addr;
+		*mmio_seq = get_bus_width(tdc, tdc->dma_sconfig.dst_addr_width);
+		*burst_size = tdc->dma_sconfig.dst_maxburst;
+		*slave_bw = tdc->dma_sconfig.dst_addr_width;
+		*csr = TEGRA_GPCDMA_CSR_DMA_MEM2IO_FC;
+		return 0;
+	case DMA_DEV_TO_MEM:
+		*apb_addr = tdc->dma_sconfig.src_addr;
+		*mmio_seq = get_bus_width(tdc, tdc->dma_sconfig.src_addr_width);
+		*burst_size = tdc->dma_sconfig.src_maxburst;
+		*slave_bw = tdc->dma_sconfig.src_addr_width;
+		*csr = TEGRA_GPCDMA_CSR_DMA_IO2MEM_FC;
+		return 0;
+	case DMA_MEM_TO_MEM:
+		*burst_size = tdc->dma_sconfig.src_addr_width;
+		*csr = TEGRA_GPCDMA_CSR_DMA_MEM2MEM;
+		return 0;
+	default:
+		dev_err(tdc2dev(tdc), "DMA direction is not supported\n");
+	}
+
+	return -EINVAL;
+}
+
+static struct dma_async_tx_descriptor *
+tegra_dma_prep_dma_memset(struct dma_chan *dc, dma_addr_t dest, int value,
+			  size_t len, unsigned long flags)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	unsigned int max_dma_count = tdc->tdma->chip_data->max_dma_count;
+	struct tegra_dma_sg_req *sg_req;
+	struct tegra_dma_desc *dma_desc;
+	unsigned long csr, mc_seq;
+
+	if ((len & 3) || (dest & 3) || len > max_dma_count) {
+		dev_err(tdc2dev(tdc),
+			"DMA length/memory address is not supported\n");
+		return NULL;
+	}
+
+	/* Set dma mode to fixed pattern */
+	csr = TEGRA_GPCDMA_CSR_DMA_FIXED_PAT;
+	/* Enable once or continuous mode */
+	csr |= TEGRA_GPCDMA_CSR_ONCE;
+	/* Enable IRQ mask */
+	csr |= TEGRA_GPCDMA_CSR_IRQ_MASK;
+	/* Enable the dma interrupt */
+	if (flags & DMA_PREP_INTERRUPT)
+		csr |= TEGRA_GPCDMA_CSR_IE_EOC;
+	/* Configure default priority weight for the channel */
+	csr |= FIELD_PREP(TEGRA_GPCDMA_CSR_WEIGHT, 1);
+
+	mc_seq =  tdc_read(tdc, TEGRA_GPCDMA_CHAN_MCSEQ);
+	/* retain stream-id and clean rest */
+	mc_seq &= TEGRA_GPCDMA_MCSEQ_STREAM_ID0_MASK;
+
+	/* Set the address wrapping */
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_WRAP0,
+						TEGRA_GPCDMA_MCSEQ_WRAP_NONE);
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_WRAP1,
+						TEGRA_GPCDMA_MCSEQ_WRAP_NONE);
+
+	/* Program outstanding MC requests */
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_REQ_COUNT, 1);
+	/* Set burst size */
+	mc_seq |= TEGRA_GPCDMA_MCSEQ_BURST_16;
+
+	dma_desc = kzalloc(struct_size(dma_desc, sg_req, 1), GFP_NOWAIT);
+	if (!dma_desc)
+		return NULL;
+
+	dma_desc->bytes_req = len;
+	dma_desc->sg_count = 1;
+	sg_req = dma_desc->sg_req;
+
+	sg_req[0].ch_regs.src_ptr = 0;
+	sg_req[0].ch_regs.dst_ptr = dest;
+	sg_req[0].ch_regs.high_addr_ptr =
+			FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (dest >> 32));
+	sg_req[0].ch_regs.fixed_pattern = value;
+	/* Word count reg takes value as (N +1) words */
+	sg_req[0].ch_regs.wcount = ((len - 4) >> 2);
+	sg_req[0].ch_regs.csr = csr;
+	sg_req[0].ch_regs.mmio_seq = 0;
+	sg_req[0].ch_regs.mc_seq = mc_seq;
+	sg_req[0].len = len;
+
+	dma_desc->cyclic = false;
+	return vchan_tx_prep(&tdc->vc, &dma_desc->vd, flags);
+}
+
+static struct dma_async_tx_descriptor *
+tegra_dma_prep_dma_memcpy(struct dma_chan *dc, dma_addr_t dest,
+			  dma_addr_t src, size_t len, unsigned long flags)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	unsigned int max_dma_count = tdc->tdma->chip_data->max_dma_count;
+	struct tegra_dma_sg_req *sg_req;
+	struct tegra_dma_desc *dma_desc;
+	unsigned long csr, mc_seq;
+
+	if ((len & 3) || (src & 3) || (dest & 3) || len > max_dma_count) {
+		dev_err(tdc2dev(tdc),
+			"DMA length/memory address is not supported\n");
+		return NULL;
+	}
+
+	/* Set dma mode to memory to memory transfer */
+	csr = TEGRA_GPCDMA_CSR_DMA_MEM2MEM;
+	/* Enable once or continuous mode */
+	csr |= TEGRA_GPCDMA_CSR_ONCE;
+	/* Enable IRQ mask */
+	csr |= TEGRA_GPCDMA_CSR_IRQ_MASK;
+	/* Enable the dma interrupt */
+	if (flags & DMA_PREP_INTERRUPT)
+		csr |= TEGRA_GPCDMA_CSR_IE_EOC;
+	/* Configure default priority weight for the channel */
+	csr |= FIELD_PREP(TEGRA_GPCDMA_CSR_WEIGHT, 1);
+
+	mc_seq =  tdc_read(tdc, TEGRA_GPCDMA_CHAN_MCSEQ);
+	/* retain stream-id and clean rest */
+	mc_seq &= (TEGRA_GPCDMA_MCSEQ_STREAM_ID0_MASK) |
+		  (TEGRA_GPCDMA_MCSEQ_STREAM_ID1_MASK);
+
+	/* Set the address wrapping */
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_WRAP0,
+			     TEGRA_GPCDMA_MCSEQ_WRAP_NONE);
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_WRAP1,
+			     TEGRA_GPCDMA_MCSEQ_WRAP_NONE);
+
+	/* Program outstanding MC requests */
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_REQ_COUNT, 1);
+	/* Set burst size */
+	mc_seq |= TEGRA_GPCDMA_MCSEQ_BURST_16;
+
+	dma_desc = kzalloc(struct_size(dma_desc, sg_req, 1), GFP_NOWAIT);
+	if (!dma_desc)
+		return NULL;
+
+	dma_desc->bytes_req = len;
+	dma_desc->sg_count = 1;
+	sg_req = dma_desc->sg_req;
+
+	sg_req[0].ch_regs.src_ptr = src;
+	sg_req[0].ch_regs.dst_ptr = dest;
+	sg_req[0].ch_regs.high_addr_ptr =
+		FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_SRC_PTR, (src >> 32));
+	sg_req[0].ch_regs.high_addr_ptr |=
+		FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (dest >> 32));
+	/* Word count reg takes value as (N +1) words */
+	sg_req[0].ch_regs.wcount = ((len - 4) >> 2);
+	sg_req[0].ch_regs.csr = csr;
+	sg_req[0].ch_regs.mmio_seq = 0;
+	sg_req[0].ch_regs.mc_seq = mc_seq;
+	sg_req[0].len = len;
+
+	dma_desc->cyclic = false;
+	return vchan_tx_prep(&tdc->vc, &dma_desc->vd, flags);
+}
+
+static struct dma_async_tx_descriptor *
+tegra_dma_prep_slave_sg(struct dma_chan *dc, struct scatterlist *sgl,
+			unsigned int sg_len, enum dma_transfer_direction direction,
+			unsigned long flags, void *context)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	unsigned int max_dma_count = tdc->tdma->chip_data->max_dma_count;
+	unsigned long csr, mc_seq, apb_ptr = 0, mmio_seq = 0;
+	enum dma_slave_buswidth slave_bw;
+	struct tegra_dma_sg_req *sg_req;
+	struct tegra_dma_desc *dma_desc;
+	struct scatterlist *sg;
+	u32 burst_size;
+	unsigned int i;
+	int ret;
+
+	if (!tdc->config_init) {
+		dev_err(tdc2dev(tdc), "DMA channel is not configured\n");
+		return NULL;
+	}
+	if (sg_len < 1) {
+		dev_err(tdc2dev(tdc), "Invalid segment length %d\n", sg_len);
+		return NULL;
+	}
+
+	ret = tegra_dma_sid_reserve(tdc, direction);
+	if (ret)
+		return NULL;
+
+	ret = get_transfer_param(tdc, direction, &apb_ptr, &mmio_seq, &csr,
+				 &burst_size, &slave_bw);
+	if (ret < 0)
+		return NULL;
+
+	/* Enable once or continuous mode */
+	csr |= TEGRA_GPCDMA_CSR_ONCE;
+	/* Program the slave id in requestor select */
+	csr |= FIELD_PREP(TEGRA_GPCDMA_CSR_REQ_SEL_MASK, tdc->slave_id);
+	/* Enable IRQ mask */
+	csr |= TEGRA_GPCDMA_CSR_IRQ_MASK;
+	/* Configure default priority weight for the channel*/
+	csr |= FIELD_PREP(TEGRA_GPCDMA_CSR_WEIGHT, 1);
+
+	/* Enable the dma interrupt */
+	if (flags & DMA_PREP_INTERRUPT)
+		csr |= TEGRA_GPCDMA_CSR_IE_EOC;
+
+	mc_seq =  tdc_read(tdc, TEGRA_GPCDMA_CHAN_MCSEQ);
+	/* retain stream-id and clean rest */
+	mc_seq &= TEGRA_GPCDMA_MCSEQ_STREAM_ID0_MASK;
+
+	/* Set the address wrapping on both MC and MMIO side */
+
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_WRAP0,
+			     TEGRA_GPCDMA_MCSEQ_WRAP_NONE);
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_WRAP1,
+			     TEGRA_GPCDMA_MCSEQ_WRAP_NONE);
+	mmio_seq |= FIELD_PREP(TEGRA_GPCDMA_MMIOSEQ_WRAP_WORD, 1);
+
+	/* Program 2 MC outstanding requests by default. */
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_REQ_COUNT, 1);
+
+	/* Setting MC burst size depending on MMIO burst size */
+	if (burst_size == 64)
+		mc_seq |= TEGRA_GPCDMA_MCSEQ_BURST_16;
+	else
+		mc_seq |= TEGRA_GPCDMA_MCSEQ_BURST_2;
+
+	dma_desc = kzalloc(struct_size(dma_desc, sg_req, 1), GFP_NOWAIT);
+	if (!dma_desc)
+		return NULL;
+
+	dma_desc->sg_count = sg_len;
+	sg_req = dma_desc->sg_req;
+
+	/* Make transfer requests */
+	for_each_sg(sgl, sg, sg_len, i) {
+		u32 len;
+		dma_addr_t mem;
+
+		mem = sg_dma_address(sg);
+		len = sg_dma_len(sg);
+
+		if ((len & 3) || (mem & 3) || len > max_dma_count) {
+			dev_err(tdc2dev(tdc),
+				"DMA length/memory address is not supported\n");
+			kfree(dma_desc);
+			return NULL;
+		}
+
+		mmio_seq |= get_burst_size(tdc, burst_size, slave_bw, len);
+		dma_desc->bytes_req += len;
+
+		if (direction == DMA_MEM_TO_DEV) {
+			sg_req[i].ch_regs.src_ptr = mem;
+			sg_req[i].ch_regs.dst_ptr = apb_ptr;
+			sg_req[i].ch_regs.high_addr_ptr =
+				FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_SRC_PTR, (mem >> 32));
+		} else if (direction == DMA_DEV_TO_MEM) {
+			sg_req[i].ch_regs.src_ptr = apb_ptr;
+			sg_req[i].ch_regs.dst_ptr = mem;
+			sg_req[i].ch_regs.high_addr_ptr =
+				FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (mem >> 32));
+		}
+
+		/*
+		 * Word count register takes input in words. Writing a value
+		 * of N into word count register means a req of (N+1) words.
+		 */
+		sg_req[i].ch_regs.wcount = ((len - 4) >> 2);
+		sg_req[i].ch_regs.csr = csr;
+		sg_req[i].ch_regs.mmio_seq = mmio_seq;
+		sg_req[i].ch_regs.mc_seq = mc_seq;
+		sg_req[i].len = len;
+	}
+
+	dma_desc->cyclic = false;
+	return vchan_tx_prep(&tdc->vc, &dma_desc->vd, flags);
+}
+
+static struct dma_async_tx_descriptor *
+tegra_dma_prep_dma_cyclic(struct dma_chan *dc, dma_addr_t buf_addr, size_t buf_len,
+			  size_t period_len, enum dma_transfer_direction direction,
+			  unsigned long flags)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	unsigned int max_dma_count = tdc->tdma->chip_data->max_dma_count;
+	struct tegra_dma_desc *dma_desc;
+	struct tegra_dma_sg_req *sg_req;
+	unsigned long csr, mc_seq, apb_ptr = 0, mmio_seq = 0;
+	unsigned int len, period_count, i;
+	dma_addr_t mem = buf_addr;
+	u32 burst_size;
+	enum dma_slave_buswidth slave_bw;
+	int ret;
+
+	if (!buf_len || !period_len) {
+		dev_err(tdc2dev(tdc), "Invalid buffer/period len\n");
+		return NULL;
+	}
+
+	if (!tdc->config_init) {
+		dev_err(tdc2dev(tdc), "DMA slave is not configured\n");
+		return NULL;
+	}
+
+	ret = tegra_dma_sid_reserve(tdc, direction);
+	if (ret)
+		return NULL;
+
+	/*
+	 * We only support cycle transfer when buf_len is multiple of
+	 * period_len.
+	 */
+	if (buf_len % period_len) {
+		dev_err(tdc2dev(tdc), "buf_len is not multiple of period_len\n");
+		return NULL;
+	}
+
+	len = period_len;
+	if ((len & 3) || (buf_addr & 3) || len > max_dma_count) {
+		dev_err(tdc2dev(tdc), "Req len/mem address is not correct\n");
+		return NULL;
+	}
+
+	ret = get_transfer_param(tdc, direction, &apb_ptr, &mmio_seq, &csr,
+				 &burst_size, &slave_bw);
+	if (ret < 0)
+		return NULL;
+
+	/* Enable once or continuous mode */
+	csr &= ~TEGRA_GPCDMA_CSR_ONCE;
+	/* Program the slave id in requestor select */
+	csr |= FIELD_PREP(TEGRA_GPCDMA_CSR_REQ_SEL_MASK, tdc->slave_id);
+	/* Enable IRQ mask */
+	csr |= TEGRA_GPCDMA_CSR_IRQ_MASK;
+	/* Configure default priority weight for the channel*/
+	csr |= FIELD_PREP(TEGRA_GPCDMA_CSR_WEIGHT, 1);
+
+	/* Enable the dma interrupt */
+	if (flags & DMA_PREP_INTERRUPT)
+		csr |= TEGRA_GPCDMA_CSR_IE_EOC;
+
+	mmio_seq |= FIELD_PREP(TEGRA_GPCDMA_MMIOSEQ_WRAP_WORD, 1);
+
+	mc_seq =  tdc_read(tdc, TEGRA_GPCDMA_CHAN_MCSEQ);
+	/* retain stream-id and clean rest */
+	mc_seq &= TEGRA_GPCDMA_MCSEQ_STREAM_ID0_MASK;
+
+	/* Set the address wrapping on both MC and MMIO side */
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_WRAP0,
+			     TEGRA_GPCDMA_MCSEQ_WRAP_NONE);
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_WRAP1,
+			     TEGRA_GPCDMA_MCSEQ_WRAP_NONE);
+
+	/* Program 2 MC outstanding requests by default. */
+	mc_seq |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_REQ_COUNT, 1);
+	/* Setting MC burst size depending on MMIO burst size */
+	if (burst_size == 64)
+		mc_seq |= TEGRA_GPCDMA_MCSEQ_BURST_16;
+	else
+		mc_seq |= TEGRA_GPCDMA_MCSEQ_BURST_2;
+
+	period_count = buf_len / period_len;
+	dma_desc = kzalloc(struct_size(dma_desc, sg_req, period_count),
+			   GFP_NOWAIT);
+	if (!dma_desc)
+		return NULL;
+
+	dma_desc->bytes_req = buf_len;
+	dma_desc->sg_count = period_count;
+
+	/* Split transfer equal to period size */
+	for (i = 0; i < period_count; i++) {
+		mmio_seq |= get_burst_size(tdc, burst_size, slave_bw, len);
+		if (direction == DMA_MEM_TO_DEV) {
+			sg_req[i].ch_regs.src_ptr = mem;
+			sg_req[i].ch_regs.dst_ptr = apb_ptr;
+			sg_req[i].ch_regs.high_addr_ptr =
+				FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_SRC_PTR, (mem >> 32));
+		} else if (direction == DMA_DEV_TO_MEM) {
+			sg_req[i].ch_regs.src_ptr = apb_ptr;
+			sg_req[i].ch_regs.dst_ptr = mem;
+			sg_req[i].ch_regs.high_addr_ptr =
+				FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (mem >> 32));
+		}
+		/*
+		 * Word count register takes input in words. Writing a value
+		 * of N into word count register means a req of (N+1) words.
+		 */
+		sg_req[i].ch_regs.wcount = ((len - 4) >> 2);
+		sg_req[i].ch_regs.csr = csr;
+		sg_req[i].ch_regs.mmio_seq = mmio_seq;
+		sg_req[i].ch_regs.mc_seq = mc_seq;
+		sg_req[i].len = len;
+
+		mem += len;
+	}
+
+	dma_desc->cyclic = true;
+
+	return vchan_tx_prep(&tdc->vc, &dma_desc->vd, flags);
+}
+
+static int tegra_dma_alloc_chan_resources(struct dma_chan *dc)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	int ret;
+
+	ret = request_irq(tdc->irq, tegra_dma_isr, 0, tdc->name, tdc);
+	if (ret) {
+		dev_err(tdc2dev(tdc), "request_irq failed for %s\n", tdc->name);
+		return ret;
+	}
+
+	dma_cookie_init(&tdc->vc.chan);
+	tdc->config_init = false;
+	return 0;
+}
+
+static void tegra_dma_chan_synchronize(struct dma_chan *dc)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+
+	vchan_synchronize(&tdc->vc);
+}
+
+static void tegra_dma_free_chan_resources(struct dma_chan *dc)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+
+	dev_dbg(tdc2dev(tdc), "Freeing channel %d\n", tdc->id);
+
+	tegra_dma_terminate_all(dc);
+
+	tasklet_kill(&tdc->vc.task);
+	tdc->config_init = false;
+	tdc->slave_id = -1;
+	tdc->sid_dir = DMA_TRANS_NONE;
+	free_irq(tdc->irq, tdc);
+	vchan_free_chan_resources(&tdc->vc);
+}
+
+static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
+					   struct of_dma *ofdma)
+{
+	struct tegra_dma *tdma = ofdma->of_dma_data;
+	struct tegra_dma_channel *tdc;
+	struct dma_chan *chan;
+
+	chan = dma_get_any_slave_channel(&tdma->dma_dev);
+	if (!chan)
+		return NULL;
+
+	tdc = to_tegra_dma_chan(chan);
+	tdc->slave_id = dma_spec->args[0];
+
+	return chan;
+}
+
+static const struct tegra_dma_chip_data tegra186_dma_chip_data = {
+	.nr_channels = 31,
+	.channel_reg_size = SZ_64K,
+	.max_dma_count = SZ_1G,
+	.hw_support_pause = false,
+};
+
+static const struct tegra_dma_chip_data tegra194_dma_chip_data = {
+	.nr_channels = 31,
+	.channel_reg_size = SZ_64K,
+	.max_dma_count = SZ_1G,
+	.hw_support_pause = true,
+};
+
+static const struct of_device_id tegra_dma_of_match[] = {
+	{
+		.compatible = "nvidia,tegra186-gpcdma",
+		.data = &tegra186_dma_chip_data,
+	}, {
+		.compatible = "nvidia,tegra194-gpcdma",
+		.data = &tegra194_dma_chip_data,
+	}, {
+	},
+};
+MODULE_DEVICE_TABLE(of, tegra_dma_of_match);
+
+static int tegra_dma_program_sid(struct tegra_dma_channel *tdc,
+				 int chan, int stream_id)
+{
+	unsigned int reg_val =  tdc_read(tdc, TEGRA_GPCDMA_CHAN_MCSEQ);
+
+	reg_val &= ~(TEGRA_GPCDMA_MCSEQ_STREAM_ID0_MASK);
+	reg_val &= ~(TEGRA_GPCDMA_MCSEQ_STREAM_ID1_MASK);
+
+	reg_val |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_STREAM_ID0_MASK, stream_id);
+	reg_val |= FIELD_PREP(TEGRA_GPCDMA_MCSEQ_STREAM_ID1_MASK, stream_id);
+
+	tdc_write(tdc, TEGRA_GPCDMA_CHAN_MCSEQ, reg_val);
+	return 0;
+}
+
+static int tegra_dma_probe(struct platform_device *pdev)
+{
+	const struct tegra_dma_chip_data *cdata = NULL;
+	struct iommu_fwspec *iommu_spec;
+	unsigned int stream_id, i;
+	struct tegra_dma *tdma;
+	struct resource	*res;
+	int ret;
+
+	cdata = of_device_get_match_data(&pdev->dev);
+
+	tdma = devm_kzalloc(&pdev->dev, sizeof(*tdma) + cdata->nr_channels *
+			sizeof(struct tegra_dma_channel), GFP_KERNEL);
+	if (!tdma)
+		return -ENOMEM;
+
+	tdma->dev = &pdev->dev;
+	tdma->chip_data = cdata;
+	platform_set_drvdata(pdev, tdma);
+
+	tdma->base_addr = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(tdma->base_addr))
+		return PTR_ERR(tdma->base_addr);
+
+	tdma->rst = devm_reset_control_get_exclusive(&pdev->dev, "gpcdma");
+	if (IS_ERR(tdma->rst)) {
+		return dev_err_probe(&pdev->dev, PTR_ERR(tdma->rst),
+			      "Missing controller reset\n");
+	}
+	reset_control_reset(tdma->rst);
+
+	tdma->dma_dev.dev = &pdev->dev;
+
+	iommu_spec = dev_iommu_fwspec_get(&pdev->dev);
+	if (!iommu_spec) {
+		dev_err(&pdev->dev, "Missing iommu stream-id\n");
+		return -EINVAL;
+	}
+	stream_id = iommu_spec->ids[0] & 0xffff;
+
+	INIT_LIST_HEAD(&tdma->dma_dev.channels);
+	for (i = 0; i < cdata->nr_channels; i++) {
+		struct tegra_dma_channel *tdc = &tdma->channels[i];
+
+		tdc->chan_base_offset = TEGRA_GPCDMA_CHANNEL_BASE_ADD_OFFSET +
+					i * cdata->channel_reg_size;
+		res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
+		if (!res) {
+			dev_err(&pdev->dev, "No irq resource for chan %d\n", i);
+			return -EINVAL;
+		}
+		tdc->irq = res->start;
+		snprintf(tdc->name, sizeof(tdc->name), "gpcdma.%d", i);
+
+		tdc->tdma = tdma;
+		tdc->id = i;
+		tdc->slave_id = -1;
+
+		vchan_init(&tdc->vc, &tdma->dma_dev);
+		tdc->vc.desc_free = tegra_dma_desc_free;
+
+		/* program stream-id for this channel */
+		tegra_dma_program_sid(tdc, i, stream_id);
+		tdc->stream_id = stream_id;
+	}
+
+	dma_cap_set(DMA_SLAVE, tdma->dma_dev.cap_mask);
+	dma_cap_set(DMA_PRIVATE, tdma->dma_dev.cap_mask);
+	dma_cap_set(DMA_MEMCPY, tdma->dma_dev.cap_mask);
+	dma_cap_set(DMA_MEMSET, tdma->dma_dev.cap_mask);
+	dma_cap_set(DMA_CYCLIC, tdma->dma_dev.cap_mask);
+
+	/*
+	 * Only word aligned transfers are supported. Set the copy
+	 * alignment shift.
+	 */
+	tdma->dma_dev.copy_align = 2;
+	tdma->dma_dev.fill_align = 2;
+	tdma->dma_dev.device_alloc_chan_resources =
+					tegra_dma_alloc_chan_resources;
+	tdma->dma_dev.device_free_chan_resources =
+					tegra_dma_free_chan_resources;
+	tdma->dma_dev.device_prep_slave_sg = tegra_dma_prep_slave_sg;
+	tdma->dma_dev.device_prep_dma_memcpy = tegra_dma_prep_dma_memcpy;
+	tdma->dma_dev.device_prep_dma_memset = tegra_dma_prep_dma_memset;
+	tdma->dma_dev.device_prep_dma_cyclic = tegra_dma_prep_dma_cyclic;
+	tdma->dma_dev.device_config = tegra_dma_slave_config;
+	tdma->dma_dev.device_terminate_all = tegra_dma_terminate_all;
+	tdma->dma_dev.device_tx_status = tegra_dma_tx_status;
+	tdma->dma_dev.device_issue_pending = tegra_dma_issue_pending;
+	tdma->dma_dev.device_pause = tegra_dma_device_pause;
+	tdma->dma_dev.device_resume = tegra_dma_device_resume;
+	tdma->dma_dev.device_synchronize = tegra_dma_chan_synchronize;
+	tdma->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+
+	ret = dma_async_device_register(&tdma->dma_dev);
+	if (ret < 0) {
+		dev_err_probe(&pdev->dev, ret,
+			      "GPC DMA driver registration failed\n");
+		return ret;
+	}
+
+	ret = of_dma_controller_register(pdev->dev.of_node,
+					 tegra_dma_of_xlate, tdma);
+	if (ret < 0) {
+		dev_err_probe(&pdev->dev, ret,
+			      "GPC DMA OF registration failed\n");
+
+		dma_async_device_unregister(&tdma->dma_dev);
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "GPC DMA driver register %d channels\n",
+		 cdata->nr_channels);
+
+	return 0;
+}
+
+static int tegra_dma_remove(struct platform_device *pdev)
+{
+	struct tegra_dma *tdma = platform_get_drvdata(pdev);
+
+	of_dma_controller_free(pdev->dev.of_node);
+	dma_async_device_unregister(&tdma->dma_dev);
+
+	return 0;
+}
+
+static int __maybe_unused tegra_dma_pm_suspend(struct device *dev)
+{
+	struct tegra_dma *tdma = dev_get_drvdata(dev);
+	unsigned int i;
+
+	for (i = 0; i < tdma->chip_data->nr_channels; i++) {
+		struct tegra_dma_channel *tdc = &tdma->channels[i];
+
+		if (tdc->dma_desc) {
+			dev_err(tdma->dev, "channel %u busy\n", i);
+			return -EBUSY;
+		}
+	}
+
+	return 0;
+}
+
+static int __maybe_unused tegra_dma_pm_resume(struct device *dev)
+{
+	struct tegra_dma *tdma = dev_get_drvdata(dev);
+	unsigned int i;
+
+	reset_control_reset(tdma->rst);
+
+	for (i = 0; i < tdma->chip_data->nr_channels; i++) {
+		struct tegra_dma_channel *tdc = &tdma->channels[i];
+
+		tegra_dma_program_sid(tdc, i, tdc->stream_id);
+	}
+
+	return 0;
+}
+
+static const struct __maybe_unused dev_pm_ops tegra_dma_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(tegra_dma_pm_suspend, tegra_dma_pm_resume)
+};
+
+static struct platform_driver tegra_dmac_driver = {
+	.driver = {
+		.name	= "tegra-gpcdma",
+		.pm	= &tegra_dma_dev_pm_ops,
+		.of_match_table = tegra_dma_of_match,
+	},
+	.probe		= tegra_dma_probe,
+	.remove		= tegra_dma_remove,
+};
+
+module_platform_driver(tegra_dmac_driver);
+
+MODULE_DESCRIPTION("NVIDIA Tegra GPC DMA Controller driver");
+MODULE_AUTHOR("Pavan Kunapuli <pkunapuli@nvidia.com>");
+MODULE_AUTHOR("Rajesh Gumasta <rgumasta@nvidia.com>");
+MODULE_LICENSE("GPL v2");