diff mbox series

[5/9] soc: apple: Add RTKit IPC library

Message ID 20220321165049.35985-6-sven@svenpeter.dev (mailing list archive)
State New, archived
Headers show
Series Apple M1 (Pro/Max) NVMe driver | expand

Commit Message

Sven Peter March 21, 2022, 4:50 p.m. UTC
Apple SoCs such as the M1 come with multiple embedded co-processors
running proprietary firmware. Communication with those is established
over a simple mailbox using the RTKit IPC protocol.

Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
 drivers/soc/apple/Kconfig          |  13 +
 drivers/soc/apple/Makefile         |   3 +
 drivers/soc/apple/rtkit-crashlog.c | 147 +++++
 drivers/soc/apple/rtkit-internal.h |  76 +++
 drivers/soc/apple/rtkit.c          | 842 +++++++++++++++++++++++++++++
 include/linux/soc/apple/rtkit.h    | 203 +++++++
 6 files changed, 1284 insertions(+)
 create mode 100644 drivers/soc/apple/rtkit-crashlog.c
 create mode 100644 drivers/soc/apple/rtkit-internal.h
 create mode 100644 drivers/soc/apple/rtkit.c
 create mode 100644 include/linux/soc/apple/rtkit.h

Comments

Arnd Bergmann March 22, 2022, 1:13 p.m. UTC | #1
On Mon, Mar 21, 2022 at 5:50 PM Sven Peter <sven@svenpeter.dev> wrote:
>
> Apple SoCs such as the M1 come with multiple embedded co-processors
> running proprietary firmware. Communication with those is established
> over a simple mailbox using the RTKit IPC protocol.
>
> Signed-off-by: Sven Peter <sven@svenpeter.dev>

> +
> +#define rtk_err(format, arg...) dev_err(rtk->dev, "RTKit: " format, ##arg)
> +#define rtk_warn(format, arg...) dev_warn(rtk->dev, "RTKit: " format, ##arg)
> +#define rtk_info(format, arg...) dev_info(rtk->dev, "RTKit: " format, ##arg)
> +#define rtk_dbg(format, arg...) dev_dbg(rtk->dev, "RTKit: " format, ##arg)

I generally don't like the custom printing macros, please just open-code
the prints where they are used, that makes it easier for other kernel
developers to see exactly what is being printed.

> +enum { APPLE_RTKIT_WORK_MSG,
> +       APPLE_RTKIT_WORK_REINIT,
> +};
> +
> +enum { APPLE_RTKIT_PWR_STATE_OFF = 0x00,
> +       APPLE_RTKIT_PWR_STATE_SLEEP = 0x01,
> +       APPLE_RTKIT_PWR_STATE_GATED = 0x02,
> +       APPLE_RTKIT_PWR_STATE_QUIESCED = 0x10,
> +       APPLE_RTKIT_PWR_STATE_ON = 0x20,
> +};

This is an odd indentation style, I would insert a newline after the 'enum {'

> +static int apple_rtkit_worker(void *data)
> +{
> +       struct apple_rtkit *rtk = data;
> +       struct apple_rtkit_work work;
> +
> +       while (!kthread_should_stop()) {
> +               wait_event_interruptible(rtk->wq,
> +                                        kfifo_len(&rtk->work_fifo) > 0 ||
> +                                                kthread_should_stop());
> +
> +               if (kthread_should_stop())
> +                       break;
> +
> +               while (kfifo_out_spinlocked(&rtk->work_fifo, &work, 1,
> +                                           &rtk->work_lock) == 1) {
> +                       switch (work.type) {
> +                       case APPLE_RTKIT_WORK_MSG:
> +                               apple_rtkit_rx(rtk, &work.msg);
> +                               break;
> +                       case APPLE_RTKIT_WORK_REINIT:
> +                               apple_rtkit_do_reinit(rtk);
> +                               break;
> +                       }
> +               }

It looks like you add quite a bit of complexity by using a custom
worker thread implementation. Can you explain what this is
needed for? Isn't this roughly the same thing that one would
get more easily with create_singlethread_workqueue()?

> +#if IS_ENABLED(CONFIG_APPLE_RTKIT)

Instead of allowing the interface to be used without CONFIG_APPLE_RTKIT,
I think it is sufficient to allow the driver itself to be built with
CONFIG_COMPILE_TEST (as you already do), and then have
drivers using it marked as 'depends on APPLE_RTKIT'
unconditionally.

> +/*
> + * Initializes the internal state required to handle RTKit. This
> + * should usually be called within _probe.
> + *
> + * @dev: Pointer to the device node this coprocessor is assocated with
> + * @cookie: opaque cookie passed to all functions defined in rtkit_ops
> + * @mbox_name: mailbox name used to communicate with the co-processor
> + * @mbox_idx: mailbox index to be used if mbox_name is NULL
> + * @ops: pointer to rtkit_ops to be used for this co-processor
> + */
> +struct apple_rtkit *apple_rtkit_init(struct device *dev, void *cookie,
> +                                    const char *mbox_name, int mbox_idx,
> +                                    const struct apple_rtkit_ops *ops);
> +
> +/*
> + * Dev-res managed version of apple_rtkit_init.
> + */
> +struct apple_rtkit *devm_apple_rtkit_init(struct device *dev, void *cookie,
> +                                         const char *mbox_name, int mbox_idx,
> +                                         const struct apple_rtkit_ops *ops);

Do we need to export both of these?

         Arnd
Alyssa Rosenzweig March 22, 2022, 5:23 p.m. UTC | #2
> +enum { APPLE_RTKIT_PWR_STATE_OFF = 0x00,
> +	APPLE_RTKIT_PWR_STATE_SLEEP = 0x01,
> +	APPLE_RTKIT_PWR_STATE_GATED = 0x02,
> +	APPLE_RTKIT_PWR_STATE_QUIESCED = 0x10,
> +	APPLE_RTKIT_PWR_STATE_ON = 0x20,
> +};

It would be great to get comments added explaining what these states
are. It's not obvious how off/sleep/gated/quiesced differ, and it's not
obvious from the code (doesn't look like GATED is used here at all?).
Are these Apple names or r/e'd names or a mix?

> +	if (!rtk->syslog_buffer.size) {
> +		rtk_warn(
> +			"received syslog message but syslog_buffer.size is zero");
> +		goto done;
> +	}
> +	if (!rtk->syslog_buffer.buffer && !rtk->syslog_buffer.iomem) {
> +		rtk_warn("received syslog message but no syslog_buffer.buffer or syslog_buffer.iomem");
> +		goto done;
> +	}

Nit: Wrapping is inconsistent between these two warns.
Robin Murphy March 22, 2022, 5:41 p.m. UTC | #3
On 2022-03-22 13:13, Arnd Bergmann wrote:
>> +#define rtk_err(format, arg...) dev_err(rtk->dev, "RTKit: " format, ##arg)
>> +#define rtk_warn(format, arg...) dev_warn(rtk->dev, "RTKit: " format, ##arg)
>> +#define rtk_info(format, arg...) dev_info(rtk->dev, "RTKit: " format, ##arg)
>> +#define rtk_dbg(format, arg...) dev_dbg(rtk->dev, "RTKit: " format, ##arg)
> 
> I generally don't like the custom printing macros, please just open-code
> the prints where they are used, that makes it easier for other kernel
> developers to see exactly what is being printed

More to the point, implicitly depending on having something named "rtk" 
in scope is pretty much inexcusable, and the only thing left after 
fixing that is what we have pr_fmt for ;)

Robin.
Krzysztof Kozlowski March 23, 2022, 11:19 a.m. UTC | #4
On 21/03/2022 17:50, Sven Peter wrote:
> Apple SoCs such as the M1 come with multiple embedded co-processors
> running proprietary firmware. Communication with those is established
> over a simple mailbox using the RTKit IPC protocol.
> 
> Signed-off-by: Sven Peter <sven@svenpeter.dev>
> ---
>  drivers/soc/apple/Kconfig          |  13 +
>  drivers/soc/apple/Makefile         |   3 +
>  drivers/soc/apple/rtkit-crashlog.c | 147 +++++
>  drivers/soc/apple/rtkit-internal.h |  76 +++
>  drivers/soc/apple/rtkit.c          | 842 +++++++++++++++++++++++++++++
>  include/linux/soc/apple/rtkit.h    | 203 +++++++
>  6 files changed, 1284 insertions(+)

Isn't this some implementation of a mailbox? If so, it should be in
drivers/mailbox. Please don't put all stuff in soc/apple, that's not how
Linux is organized. To drivers/soc usually we put drivers which do not
fit regular subsystems.

Best regards,
Krzysztof
Sven Peter April 2, 2022, 12:50 p.m. UTC | #5
On Tue, Mar 22, 2022, at 18:23, Alyssa Rosenzweig wrote:
>> +enum { APPLE_RTKIT_PWR_STATE_OFF = 0x00,
>> +	APPLE_RTKIT_PWR_STATE_SLEEP = 0x01,
>> +	APPLE_RTKIT_PWR_STATE_GATED = 0x02,
>> +	APPLE_RTKIT_PWR_STATE_QUIESCED = 0x10,
>> +	APPLE_RTKIT_PWR_STATE_ON = 0x20,
>> +};
>
> It would be great to get comments added explaining what these states
> are. It's not obvious how off/sleep/gated/quiesced differ, and it's not
> obvious from the code (doesn't look like GATED is used here at all?).
> Are these Apple names or r/e'd names or a mix?

Good point. They come from XNU's serial output, I'll add comments
for those where I know exactly what they do. I'll also remove GATED
for now since that's not used yet.

>
>> +	if (!rtk->syslog_buffer.size) {
>> +		rtk_warn(
>> +			"received syslog message but syslog_buffer.size is zero");
>> +		goto done;
>> +	}
>> +	if (!rtk->syslog_buffer.buffer && !rtk->syslog_buffer.iomem) {
>> +		rtk_warn("received syslog message but no syslog_buffer.buffer or syslog_buffer.iomem");
>> +		goto done;
>> +	}
>
> Nit: Wrapping is inconsistent between these two warns.

Will fix it while getting rid of the rtk_ macros.

Sven
Sven Peter April 2, 2022, 12:56 p.m. UTC | #6
On Tue, Mar 22, 2022, at 14:13, Arnd Bergmann wrote:
> On Mon, Mar 21, 2022 at 5:50 PM Sven Peter <sven@svenpeter.dev> wrote:
>>
>> Apple SoCs such as the M1 come with multiple embedded co-processors
>> running proprietary firmware. Communication with those is established
>> over a simple mailbox using the RTKit IPC protocol.
>>
>> Signed-off-by: Sven Peter <sven@svenpeter.dev>
>
>> +
>> +#define rtk_err(format, arg...) dev_err(rtk->dev, "RTKit: " format, ##arg)
>> +#define rtk_warn(format, arg...) dev_warn(rtk->dev, "RTKit: " format, ##arg)
>> +#define rtk_info(format, arg...) dev_info(rtk->dev, "RTKit: " format, ##arg)
>> +#define rtk_dbg(format, arg...) dev_dbg(rtk->dev, "RTKit: " format, ##arg)
>
> I generally don't like the custom printing macros, please just open-code
> the prints where they are used, that makes it easier for other kernel
> developers to see exactly what is being printed.
>

Sure, I'll remove them.

>> +enum { APPLE_RTKIT_WORK_MSG,
>> +       APPLE_RTKIT_WORK_REINIT,
>> +};
>> +
>> +enum { APPLE_RTKIT_PWR_STATE_OFF = 0x00,
>> +       APPLE_RTKIT_PWR_STATE_SLEEP = 0x01,
>> +       APPLE_RTKIT_PWR_STATE_GATED = 0x02,
>> +       APPLE_RTKIT_PWR_STATE_QUIESCED = 0x10,
>> +       APPLE_RTKIT_PWR_STATE_ON = 0x20,
>> +};
>
> This is an odd indentation style, I would insert a newline after the 'enum {'

Yeah, I blame clang-format and me not double-checking the result for that one.
I'll add the newline.

>
>> +static int apple_rtkit_worker(void *data)
>> +{
>> +       struct apple_rtkit *rtk = data;
>> +       struct apple_rtkit_work work;
>> +
>> +       while (!kthread_should_stop()) {
>> +               wait_event_interruptible(rtk->wq,
>> +                                        kfifo_len(&rtk->work_fifo) > 0 ||
>> +                                                kthread_should_stop());
>> +
>> +               if (kthread_should_stop())
>> +                       break;
>> +
>> +               while (kfifo_out_spinlocked(&rtk->work_fifo, &work, 1,
>> +                                           &rtk->work_lock) == 1) {
>> +                       switch (work.type) {
>> +                       case APPLE_RTKIT_WORK_MSG:
>> +                               apple_rtkit_rx(rtk, &work.msg);
>> +                               break;
>> +                       case APPLE_RTKIT_WORK_REINIT:
>> +                               apple_rtkit_do_reinit(rtk);
>> +                               break;
>> +                       }
>> +               }
>
> It looks like you add quite a bit of complexity by using a custom
> worker thread implementation. Can you explain what this is
> needed for? Isn't this roughly the same thing that one would
> get more easily with create_singlethread_workqueue()?

I originally had just a workqueue here but I can only put
one instance of e.g. APPLE_RTKIT_WORK_MSG onto these.
There could however be a new incoming message while the previous
one is still being handled and I couldn't figure out a way
to handle that with workqueues without introducing a race.


>
>> +#if IS_ENABLED(CONFIG_APPLE_RTKIT)
>
> Instead of allowing the interface to be used without CONFIG_APPLE_RTKIT,
> I think it is sufficient to allow the driver itself to be built with
> CONFIG_COMPILE_TEST (as you already do), and then have
> drivers using it marked as 'depends on APPLE_RTKIT'
> unconditionally.

That's indeed much simpler and what I wanted to achieve. I just couldn't
figure out how to do it. I'll use your approach! 

>
>> +/*
>> + * Initializes the internal state required to handle RTKit. This
>> + * should usually be called within _probe.
>> + *
>> + * @dev: Pointer to the device node this coprocessor is assocated with
>> + * @cookie: opaque cookie passed to all functions defined in rtkit_ops
>> + * @mbox_name: mailbox name used to communicate with the co-processor
>> + * @mbox_idx: mailbox index to be used if mbox_name is NULL
>> + * @ops: pointer to rtkit_ops to be used for this co-processor
>> + */
>> +struct apple_rtkit *apple_rtkit_init(struct device *dev, void *cookie,
>> +                                    const char *mbox_name, int mbox_idx,
>> +                                    const struct apple_rtkit_ops *ops);
>> +
>> +/*
>> + * Dev-res managed version of apple_rtkit_init.
>> + */
>> +struct apple_rtkit *devm_apple_rtkit_init(struct device *dev, void *cookie,
>> +                                         const char *mbox_name, int mbox_idx,
>> +                                         const struct apple_rtkit_ops *ops);
>
> Do we need to export both of these?

No, only devm_apple_rtkit_init needs to be exported.


Thanks,


Sven
Sven Peter April 2, 2022, 1:51 p.m. UTC | #7
On Wed, Mar 23, 2022, at 12:19, Krzysztof Kozlowski wrote:
> On 21/03/2022 17:50, Sven Peter wrote:
>> Apple SoCs such as the M1 come with multiple embedded co-processors
>> running proprietary firmware. Communication with those is established
>> over a simple mailbox using the RTKit IPC protocol.
>> 
>> Signed-off-by: Sven Peter <sven@svenpeter.dev>
>> ---
>>  drivers/soc/apple/Kconfig          |  13 +
>>  drivers/soc/apple/Makefile         |   3 +
>>  drivers/soc/apple/rtkit-crashlog.c | 147 +++++
>>  drivers/soc/apple/rtkit-internal.h |  76 +++
>>  drivers/soc/apple/rtkit.c          | 842 +++++++++++++++++++++++++++++
>>  include/linux/soc/apple/rtkit.h    | 203 +++++++
>>  6 files changed, 1284 insertions(+)
>
> Isn't this some implementation of a mailbox? If so, it should be in
> drivers/mailbox. Please don't put all stuff in soc/apple, that's not how
> Linux is organized. To drivers/soc usually we put drivers which do not
> fit regular subsystems.
>

I put this into soc/apple because I don't think it fits within the mailbox
framework very well.
(It actually uses the mailbox framework for the actual communication
with the hardware with a driver that's already upstream.)

Essentially, the mailbox subsystem provides a common API to send and
receive messages over indepedent hardware channels and devicetree bindings
to describe the relationship between those channels and other drivers.

One of the features that doesn't really fit is that we need to be able
to start, shutdown and re-start these co-processors. The NVMe driver
actually doesn't need to send/receive any messages except those required
to setup the common syslog/crashlog/etc. interfaces.
The mailbox framework would have to be extended to support these specific
use cases.

Another thing that doesn't fit is the memory management: These co-processors
sometimes need shared memory buffers to e.g. send syslog messages.
They always request these buffers with an IPC message but then there are
different possibilities:

	- For some processor the DMA API can just be used and an IOVA must be
	  sent back. For NVMe these buffers must additionally be allowed in this
	  SART address filter.
	- At least one other processor (SMC) does not request such buffers but
	  instead just sends a pointer into MMIO space and the buffer must be
	  accessed using readl/writel. This MMIO memory region is used for
	  both the common buffers (syslog etc.) and for the actual shared buffers
	  used for communication, such that the resource would have to be shared
	  across drivers.
	- And yet another coprocessor (for the display controller) requests some
	  buffers with an already existing IOVA that than need to be mapped
	  specifically inside the IOMMU.

Each of these co-processors also provides a single function and most
of them don't even have different endpoints. And even those that do (DCP) will
just become a single driver since all those endpoints are very much related.

While it's not impossible to do all that by extending and forcing this into the
mailbox framework at lest I think that it doesn't fit very well and would just
create unneccesarry impedance.


Best,


Sven
Krzysztof Kozlowski April 2, 2022, 4:08 p.m. UTC | #8
On 02/04/2022 15:51, Sven Peter wrote:
> On Wed, Mar 23, 2022, at 12:19, Krzysztof Kozlowski wrote:
>> On 21/03/2022 17:50, Sven Peter wrote:
>>> Apple SoCs such as the M1 come with multiple embedded co-processors
>>> running proprietary firmware. Communication with those is established
>>> over a simple mailbox using the RTKit IPC protocol.
>>>
>>> Signed-off-by: Sven Peter <sven@svenpeter.dev>
>>> ---
>>>  drivers/soc/apple/Kconfig          |  13 +
>>>  drivers/soc/apple/Makefile         |   3 +
>>>  drivers/soc/apple/rtkit-crashlog.c | 147 +++++
>>>  drivers/soc/apple/rtkit-internal.h |  76 +++
>>>  drivers/soc/apple/rtkit.c          | 842 +++++++++++++++++++++++++++++
>>>  include/linux/soc/apple/rtkit.h    | 203 +++++++
>>>  6 files changed, 1284 insertions(+)
>>
>> Isn't this some implementation of a mailbox? If so, it should be in
>> drivers/mailbox. Please don't put all stuff in soc/apple, that's not how
>> Linux is organized. To drivers/soc usually we put drivers which do not
>> fit regular subsystems.
>>
> 
> I put this into soc/apple because I don't think it fits within the mailbox
> framework very well.
> (It actually uses the mailbox framework for the actual communication
> with the hardware with a driver that's already upstream.)
> 
> Essentially, the mailbox subsystem provides a common API to send and
> receive messages over indepedent hardware channels and devicetree bindings
> to describe the relationship between those channels and other drivers.
> 
> One of the features that doesn't really fit is that we need to be able
> to start, shutdown and re-start these co-processors. The NVMe driver
> actually doesn't need to send/receive any messages except those required
> to setup the common syslog/crashlog/etc. interfaces.
> The mailbox framework would have to be extended to support these specific
> use cases.
> 
> Another thing that doesn't fit is the memory management: These co-processors
> sometimes need shared memory buffers to e.g. send syslog messages.
> They always request these buffers with an IPC message but then there are
> different possibilities:
> 
> 	- For some processor the DMA API can just be used and an IOVA must be
> 	  sent back. For NVMe these buffers must additionally be allowed in this
> 	  SART address filter.
> 	- At least one other processor (SMC) does not request such buffers but
> 	  instead just sends a pointer into MMIO space and the buffer must be
> 	  accessed using readl/writel. This MMIO memory region is used for
> 	  both the common buffers (syslog etc.) and for the actual shared buffers
> 	  used for communication, such that the resource would have to be shared
> 	  across drivers.
> 	- And yet another coprocessor (for the display controller) requests some
> 	  buffers with an already existing IOVA that than need to be mapped
> 	  specifically inside the IOMMU.
> 
> Each of these co-processors also provides a single function and most
> of them don't even have different endpoints. And even those that do (DCP) will
> just become a single driver since all those endpoints are very much related.
> 
> While it's not impossible to do all that by extending and forcing this into the
> mailbox framework at lest I think that it doesn't fit very well and would just
> create unneccesarry impedance.

Thanks for explanation. I don't know the mailbox framework well enough
to advise you, so I don't mind keeping it in current location (drivers/soc).

Best regards,
Krzysztof
Arnd Bergmann April 2, 2022, 6:30 p.m. UTC | #9
On Sat, Apr 2, 2022 at 2:56 PM Sven Peter <sven@svenpeter.dev> wrote:
> On Tue, Mar 22, 2022, at 14:13, Arnd Bergmann wrote:
> >> +static int apple_rtkit_worker(void *data)
> >> +{
> >> +       struct apple_rtkit *rtk = data;
> >> +       struct apple_rtkit_work work;
> >> +
> >> +       while (!kthread_should_stop()) {
> >> +               wait_event_interruptible(rtk->wq,
> >> +                                        kfifo_len(&rtk->work_fifo) > 0 ||
> >> +                                                kthread_should_stop());
> >> +
> >> +               if (kthread_should_stop())
> >> +                       break;
> >> +
> >> +               while (kfifo_out_spinlocked(&rtk->work_fifo, &work, 1,
> >> +                                           &rtk->work_lock) == 1) {
> >> +                       switch (work.type) {
> >> +                       case APPLE_RTKIT_WORK_MSG:
> >> +                               apple_rtkit_rx(rtk, &work.msg);
> >> +                               break;
> >> +                       case APPLE_RTKIT_WORK_REINIT:
> >> +                               apple_rtkit_do_reinit(rtk);
> >> +                               break;
> >> +                       }
> >> +               }
> >
> > It looks like you add quite a bit of complexity by using a custom
> > worker thread implementation. Can you explain what this is
> > needed for? Isn't this roughly the same thing that one would
> > get more easily with create_singlethread_workqueue()?
>
> I originally had just a workqueue here but I can only put
> one instance of e.g. APPLE_RTKIT_WORK_MSG onto these.
> There could however be a new incoming message while the previous
> one is still being handled and I couldn't figure out a way
> to handle that with workqueues without introducing a race.

Are you trying to avoid dynamic allocation of the messages then
and have no other place that you can embed it in?

If you kmalloc() a messages that embeds a work_struct, you can
enqueue as many of those as you want, but the allocation adds
complexity through the need for error handling etc.

I wonder if you can change the mailbox driver to use a threaded
irq handler, which I think should ensure that the callback here
is run in process context, avoiding the need to defer execution
within the rtkit driver.

         Arnd
Sven Peter April 3, 2022, 10:45 a.m. UTC | #10
On Sat, Apr 2, 2022, at 20:30, Arnd Bergmann wrote:
> On Sat, Apr 2, 2022 at 2:56 PM Sven Peter <sven@svenpeter.dev> wrote:
>> On Tue, Mar 22, 2022, at 14:13, Arnd Bergmann wrote:
>> >> +static int apple_rtkit_worker(void *data)
>> >> +{
>> >> +       struct apple_rtkit *rtk = data;
>> >> +       struct apple_rtkit_work work;
>> >> +
>> >> +       while (!kthread_should_stop()) {
>> >> +               wait_event_interruptible(rtk->wq,
>> >> +                                        kfifo_len(&rtk->work_fifo) > 0 ||
>> >> +                                                kthread_should_stop());
>> >> +
>> >> +               if (kthread_should_stop())
>> >> +                       break;
>> >> +
>> >> +               while (kfifo_out_spinlocked(&rtk->work_fifo, &work, 1,
>> >> +                                           &rtk->work_lock) == 1) {
>> >> +                       switch (work.type) {
>> >> +                       case APPLE_RTKIT_WORK_MSG:
>> >> +                               apple_rtkit_rx(rtk, &work.msg);
>> >> +                               break;
>> >> +                       case APPLE_RTKIT_WORK_REINIT:
>> >> +                               apple_rtkit_do_reinit(rtk);
>> >> +                               break;
>> >> +                       }
>> >> +               }
>> >
>> > It looks like you add quite a bit of complexity by using a custom
>> > worker thread implementation. Can you explain what this is
>> > needed for? Isn't this roughly the same thing that one would
>> > get more easily with create_singlethread_workqueue()?
>>
>> I originally had just a workqueue here but I can only put
>> one instance of e.g. APPLE_RTKIT_WORK_MSG onto these.
>> There could however be a new incoming message while the previous
>> one is still being handled and I couldn't figure out a way
>> to handle that with workqueues without introducing a race.
>
> Are you trying to avoid dynamic allocation of the messages then
> and have no other place that you can embed it in?

Yeah, I didn't want to allocate anything because of the added
complexity here like you mentioned.

>
> If you kmalloc() a messages that embeds a work_struct, you can
> enqueue as many of those as you want, but the allocation adds
> complexity through the need for error handling etc.
>
> I wonder if you can change the mailbox driver to use a threaded
> irq handler, which I think should ensure that the callback here
> is run in process context, avoiding the need to defer execution
> within the rtkit driver.

Hrm, I just realized that's already the case. mailbox_client.h documents
rx_callback as "Atomic callback to provide client the data received"
but since we know rtkit will only ever be combined with that specific
Apple mailbox we could get away with just ignoring that.
It's a small hack but it might be worth it since it would reduce
the complexity inside rtkit.

Sven
Rob Herring (Arm) April 4, 2022, 3:02 p.m. UTC | #11
On Sat, Apr 02, 2022 at 03:51:46PM +0200, Sven Peter wrote:
> On Wed, Mar 23, 2022, at 12:19, Krzysztof Kozlowski wrote:
> > On 21/03/2022 17:50, Sven Peter wrote:
> >> Apple SoCs such as the M1 come with multiple embedded co-processors
> >> running proprietary firmware. Communication with those is established
> >> over a simple mailbox using the RTKit IPC protocol.
> >> 
> >> Signed-off-by: Sven Peter <sven@svenpeter.dev>
> >> ---
> >>  drivers/soc/apple/Kconfig          |  13 +
> >>  drivers/soc/apple/Makefile         |   3 +
> >>  drivers/soc/apple/rtkit-crashlog.c | 147 +++++
> >>  drivers/soc/apple/rtkit-internal.h |  76 +++
> >>  drivers/soc/apple/rtkit.c          | 842 +++++++++++++++++++++++++++++
> >>  include/linux/soc/apple/rtkit.h    | 203 +++++++
> >>  6 files changed, 1284 insertions(+)
> >
> > Isn't this some implementation of a mailbox? If so, it should be in
> > drivers/mailbox. Please don't put all stuff in soc/apple, that's not how
> > Linux is organized. To drivers/soc usually we put drivers which do not
> > fit regular subsystems.
> >
> 
> I put this into soc/apple because I don't think it fits within the mailbox
> framework very well.
> (It actually uses the mailbox framework for the actual communication
> with the hardware with a driver that's already upstream.)
> 
> Essentially, the mailbox subsystem provides a common API to send and
> receive messages over indepedent hardware channels and devicetree bindings
> to describe the relationship between those channels and other drivers.
> 
> One of the features that doesn't really fit is that we need to be able
> to start, shutdown and re-start these co-processors. The NVMe driver

remoteproc does that. Did you look at it? Most remoteproc drivers use 
some combination of mailboxes and shared memory.

Rob
Hector Martin April 4, 2022, 3:47 p.m. UTC | #12
On 05/04/2022 00.02, Rob Herring wrote:
> On Sat, Apr 02, 2022 at 03:51:46PM +0200, Sven Peter wrote:
>> On Wed, Mar 23, 2022, at 12:19, Krzysztof Kozlowski wrote:
>>> On 21/03/2022 17:50, Sven Peter wrote:
>>>> Apple SoCs such as the M1 come with multiple embedded co-processors
>>>> running proprietary firmware. Communication with those is established
>>>> over a simple mailbox using the RTKit IPC protocol.
>>>>
>>>> Signed-off-by: Sven Peter <sven@svenpeter.dev>
>>>> ---
>>>>  drivers/soc/apple/Kconfig          |  13 +
>>>>  drivers/soc/apple/Makefile         |   3 +
>>>>  drivers/soc/apple/rtkit-crashlog.c | 147 +++++
>>>>  drivers/soc/apple/rtkit-internal.h |  76 +++
>>>>  drivers/soc/apple/rtkit.c          | 842 +++++++++++++++++++++++++++++
>>>>  include/linux/soc/apple/rtkit.h    | 203 +++++++
>>>>  6 files changed, 1284 insertions(+)
>>>
>>> Isn't this some implementation of a mailbox? If so, it should be in
>>> drivers/mailbox. Please don't put all stuff in soc/apple, that's not how
>>> Linux is organized. To drivers/soc usually we put drivers which do not
>>> fit regular subsystems.
>>>
>>
>> I put this into soc/apple because I don't think it fits within the mailbox
>> framework very well.
>> (It actually uses the mailbox framework for the actual communication
>> with the hardware with a driver that's already upstream.)
>>
>> Essentially, the mailbox subsystem provides a common API to send and
>> receive messages over indepedent hardware channels and devicetree bindings
>> to describe the relationship between those channels and other drivers.
>>
>> One of the features that doesn't really fit is that we need to be able
>> to start, shutdown and re-start these co-processors. The NVMe driver
> 
> remoteproc does that. Did you look at it? Most remoteproc drivers use 
> some combination of mailboxes and shared memory.

Remoteproc seems to be mostly about providing a standard interface for
loading firmware images and kickstarting somewhat generic remote
processors, as well as some high-level stuff for virtio. None of that is
useful to us as far as I can tell, because Linux doesn't load the
firmware for these things, it is pre-loaded by the bootloader and
therefore they might as well be fixed-function hardware as far as we're
concerned.

I can certainly see some similarities between the resourceproc API and
what we're doing, but I don't see what it would do for us other than
cause an impedance mismatch. Does it actually *do* something we can use?
Keep in mind these are Apple copros running Apple firmware that will
only ever talk to drivers we write for Apple machines, and we don't
control the firmware.

Impediance mismatches on first glance:

- The assumption that firmware is loaded by Linux seems to be hard-coded
into the subsystem
- Only one boot/shutdown path, while we need different power states and
boot modes depending on the specific instance
- The concept of the "resource table"; we have something similar for at
least one copro, but it's brokered via exchanged messages after it is
booted, and not something we can just look up in the firmware (our plan
was to just put the requested regions in the DT reg node and name them;
the firmware then *after boot* provides a list of mappings it wants from
that list and they can be mapped at that point). At least one other
copro does a subset of this an entirely different way altogether. Apple
aren't consistent and we can't do anything about that.
- Rproc trace buffers: Apple does syslogs but a different, incompatible way.
- ELF coredumps: even if this were useful for the blobs we get, the
blobs loaded by the bootloader themselves are Mach-O binaries, not ELF,
so that'd require some funny binary format conversion on one end or the
other to be able to line them up for postmortem debugging. And Apple's
crashdump format is a custom tag/value type thing.

I'm certainly willing to be convinced to use a kernel subsystem if it
actually does something useful for us, but last time we did that when it
wasn't entirely clear we should (mailbox, for the hardware underlying
these coprocessors) it just resulted in a bunch of headaches because
that subsystem is poorly designed and doesn't seem to have bought us
anything other than limitations. e.g. it is using suboptimal queueing
right now, and we had to switch to the atomic API to make SMC work,
which ends up even lower level, and isn't even properly documented and
different drivers interpret differently, so now it's just pure added
complexity and confusion for ~no gain over just reading/writing the
mailbox registers, which would've been *much* simpler (and more
performant than introducing additional queuing, since the hardware
*does* queuing now which we can't use because mailbox doesn't support
it). Remoteproc kind of seems like an even worse fit here...

Oh, and these device producer/consumer relations cannot be computed
statically as far as I can tell, so each one we introduce is another
special case in distro initramfs image building, since they need to
encode magic additional device-specific module dependency information
somehow since it isn't available in depmod, but only encoded in DTs
which are not necessarily known at initramfs build time.
diff mbox series

Patch

diff --git a/drivers/soc/apple/Kconfig b/drivers/soc/apple/Kconfig
index 8c37ffd53fbd..feb56419ac3c 100644
--- a/drivers/soc/apple/Kconfig
+++ b/drivers/soc/apple/Kconfig
@@ -17,6 +17,19 @@  config APPLE_PMGR_PWRSTATE
 	  controls for SoC devices. This driver manages them through the
 	  generic power domain framework, and also provides reset support.
 
+config APPLE_RTKIT
+	tristate "Apple RTKit co-processor IPC protocol"
+	depends on MAILBOX
+	depends on ARCH_APPLE || (COMPILE_TEST && 64BIT)
+	default ARCH_APPLE
+	help
+	  Apple SoCs such as the M1 come with various co-processors running
+	  their proprietary RTKit operating system. This option enables support
+	  for the protocol library used to communicate with those. It is used
+	  by various client drivers.
+
+	  Say 'y' here if you have an Apple SoC.
+
 config APPLE_SART
 	tristate "Apple SART DMA address filter"
 	depends on ARCH_APPLE || COMPILE_TEST
diff --git a/drivers/soc/apple/Makefile b/drivers/soc/apple/Makefile
index c83c66317098..e293770cf66d 100644
--- a/drivers/soc/apple/Makefile
+++ b/drivers/soc/apple/Makefile
@@ -1,5 +1,8 @@ 
 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_APPLE_PMGR_PWRSTATE)	+= apple-pmgr-pwrstate.o
 
+obj-$(CONFIG_APPLE_RTKIT) += apple-rtkit.o
+apple-rtkit-y = rtkit.o rtkit-crashlog.o
+
 obj-$(CONFIG_APPLE_SART) += apple-sart.o
 apple-sart-y = sart.o
diff --git a/drivers/soc/apple/rtkit-crashlog.c b/drivers/soc/apple/rtkit-crashlog.c
new file mode 100644
index 000000000000..4612c8997632
--- /dev/null
+++ b/drivers/soc/apple/rtkit-crashlog.c
@@ -0,0 +1,147 @@ 
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple RTKit IPC library
+ * Copyright (C) The Asahi Linux Contributors
+ */
+#include "rtkit-internal.h"
+
+#define FOURCC(a, b, c, d)                                                     \
+	(((u32)(a) << 24) | ((u32)(b) << 16) | ((u32)(c) << 8) | ((u32)(d)))
+
+#define APPLE_RTKIT_CRASHLOG_HEADER FOURCC('C', 'L', 'H', 'E')
+#define APPLE_RTKIT_CRASHLOG_STR FOURCC('C', 's', 't', 'r')
+#define APPLE_RTKIT_CRASHLOG_VERSION FOURCC('C', 'v', 'e', 'r')
+#define APPLE_RTKIT_CRASHLOG_MBOX FOURCC('C', 'm', 'b', 'x')
+#define APPLE_RTKIT_CRASHLOG_TIME FOURCC('C', 't', 'i', 'm')
+
+struct apple_rtkit_crashlog_header {
+	u32 fourcc;
+	u32 version;
+	u32 size;
+	u32 flags;
+	u8 _unk[16];
+};
+static_assert(sizeof(struct apple_rtkit_crashlog_header) == 0x20);
+
+struct apple_rtkit_crashlog_mbox_entry {
+	u64 msg0;
+	u64 msg1;
+	u32 timestamp;
+	u8 _unk[4];
+};
+static_assert(sizeof(struct apple_rtkit_crashlog_mbox_entry) == 0x18);
+
+static void apple_rtkit_crashlog_dump_str(struct apple_rtkit *rtk, u8 *bfr,
+					  size_t size)
+{
+	u32 idx;
+	u8 *ptr, *end;
+
+	memcpy(&idx, bfr, 4);
+
+	ptr = bfr + 4;
+	end = bfr + size;
+	while (ptr < end) {
+		u8 *newline = memchr(ptr, '\n', end - ptr);
+
+		if (newline) {
+			u8 tmp = *newline;
+			*newline = '\0';
+			rtk_warn("Message (id=%x): %s\n", idx, ptr);
+			*newline = tmp;
+			ptr = newline + 1;
+		} else {
+			rtk_warn("Message (id=%x): %s", idx, ptr);
+			break;
+		}
+	}
+}
+
+static void apple_rtkit_crashlog_dump_version(struct apple_rtkit *rtk, u8 *bfr,
+					      size_t size)
+{
+	rtk_warn("Version: %s", bfr + 16);
+}
+
+static void apple_rtkit_crashlog_dump_time(struct apple_rtkit *rtk, u8 *bfr,
+					   size_t size)
+{
+	u64 crash_time;
+
+	memcpy(&crash_time, bfr, 8);
+	rtk_warn("Crash time: %lld", crash_time);
+}
+
+static void apple_rtkit_crashlog_dump_mailbox(struct apple_rtkit *rtk, u8 *bfr,
+					      size_t size)
+{
+	u32 type, index, i;
+	size_t n_messages;
+	struct apple_rtkit_crashlog_mbox_entry entry;
+
+	memcpy(&type, bfr + 16, 4);
+	memcpy(&index, bfr + 24, 4);
+	n_messages = (size - 28) / sizeof(entry);
+
+	rtk_warn("Mailbox history (type = %d, index = %d)", type, index);
+	for (i = 0; i < n_messages; ++i) {
+		memcpy(&entry, bfr + 28 + i * sizeof(entry), sizeof(entry));
+		rtk_warn(" #%03d@%08x: %016llx %016llx", i, entry.timestamp,
+			 entry.msg0, entry.msg1);
+	}
+}
+
+void apple_rtkit_crashlog_dump(struct apple_rtkit *rtk, u8 *bfr, size_t size)
+{
+	size_t offset;
+	u32 section_fourcc, section_size;
+	struct apple_rtkit_crashlog_header header;
+
+	memcpy(&header, bfr, sizeof(header));
+	if (header.fourcc != APPLE_RTKIT_CRASHLOG_HEADER) {
+		rtk_warn("Expected crashlog header but got %x", header.fourcc);
+		return;
+	}
+
+	if (header.size > size) {
+		rtk_warn("Crashlog size (%x) is too large", header.size);
+		return;
+	}
+
+	size = header.size;
+	offset = sizeof(header);
+
+	while (offset < size) {
+		memcpy(&section_fourcc, bfr + offset, 4);
+		memcpy(&section_size, bfr + offset + 12, 4);
+
+		switch (section_fourcc) {
+		case APPLE_RTKIT_CRASHLOG_HEADER:
+			rtk_dbg("End of crashlog reached");
+			return;
+		case APPLE_RTKIT_CRASHLOG_STR:
+			apple_rtkit_crashlog_dump_str(rtk, bfr + offset + 16,
+						      section_size);
+			break;
+		case APPLE_RTKIT_CRASHLOG_VERSION:
+			apple_rtkit_crashlog_dump_version(
+				rtk, bfr + offset + 16, section_size);
+			break;
+		case APPLE_RTKIT_CRASHLOG_MBOX:
+			apple_rtkit_crashlog_dump_mailbox(
+				rtk, bfr + offset + 16, section_size);
+			break;
+		case APPLE_RTKIT_CRASHLOG_TIME:
+			apple_rtkit_crashlog_dump_time(rtk, bfr + offset + 16,
+						       section_size);
+			break;
+		default:
+			rtk_warn("Unknown crashlog section: %x",
+				 section_fourcc);
+		}
+
+		offset += section_size;
+	}
+
+	rtk_warn("End of crashlog reached but no footer present");
+}
diff --git a/drivers/soc/apple/rtkit-internal.h b/drivers/soc/apple/rtkit-internal.h
new file mode 100644
index 000000000000..6ff8b2cd2532
--- /dev/null
+++ b/drivers/soc/apple/rtkit-internal.h
@@ -0,0 +1,76 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+/*
+ * Apple RTKit IPC library
+ * Copyright (C) The Asahi Linux Contributors
+ */
+
+#ifndef _APPLE_RTKIT_INTERAL_H
+#define _APPLE_RTKIT_INTERAL_H
+
+#include <linux/apple-mailbox.h>
+#include <linux/bitfield.h>
+#include <linux/bitmap.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/io.h>
+#include <linux/kthread.h>
+#include <linux/kfifo.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/soc/apple/rtkit.h>
+#include <linux/wait.h>
+
+#define rtk_err(format, arg...) dev_err(rtk->dev, "RTKit: " format, ##arg)
+#define rtk_warn(format, arg...) dev_warn(rtk->dev, "RTKit: " format, ##arg)
+#define rtk_info(format, arg...) dev_info(rtk->dev, "RTKit: " format, ##arg)
+#define rtk_dbg(format, arg...) dev_dbg(rtk->dev, "RTKit: " format, ##arg)
+
+
+#define APPLE_RTKIT_APP_ENDPOINT_START 0x20
+#define APPLE_RTKIT_MAX_ENDPOINTS 0x100
+
+struct apple_rtkit_work {
+	unsigned int type;
+	struct apple_mbox_msg msg;
+};
+
+struct apple_rtkit {
+	void *cookie;
+	const struct apple_rtkit_ops *ops;
+	struct device *dev;
+	struct mbox_client mbox_cl;
+	struct mbox_chan *mbox_chan;
+
+	struct completion epmap_completion;
+	struct completion reinit_completion;
+	struct completion iop_pwr_ack_completion;
+	struct completion ap_pwr_ack_completion;
+
+	int boot_result;
+	int version;
+
+	unsigned int iop_power_state;
+	unsigned int ap_power_state;
+	bool crashed;
+
+	struct task_struct *task;
+
+	struct wait_queue_head wq;
+	DECLARE_KFIFO(work_fifo, struct apple_rtkit_work, 64);
+	spinlock_t work_lock;
+
+	DECLARE_BITMAP(endpoints, APPLE_RTKIT_MAX_ENDPOINTS);
+
+	struct apple_rtkit_shmem ioreport_buffer;
+	struct apple_rtkit_shmem crashlog_buffer;
+
+	struct apple_rtkit_shmem syslog_buffer;
+	char *syslog_msg_buffer;
+	size_t syslog_n_entries;
+	size_t syslog_msg_size;
+};
+
+void apple_rtkit_crashlog_dump(struct apple_rtkit *rtk, u8 *bfr, size_t size);
+
+#endif
diff --git a/drivers/soc/apple/rtkit.c b/drivers/soc/apple/rtkit.c
new file mode 100644
index 000000000000..7a93c6a99ae9
--- /dev/null
+++ b/drivers/soc/apple/rtkit.c
@@ -0,0 +1,842 @@ 
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple RTKit IPC library
+ * Copyright (C) The Asahi Linux Contributors
+ */
+
+//#define DEBUG
+
+#include "rtkit-internal.h"
+
+enum { APPLE_RTKIT_WORK_MSG,
+	APPLE_RTKIT_WORK_REINIT,
+};
+
+enum { APPLE_RTKIT_PWR_STATE_OFF = 0x00,
+	APPLE_RTKIT_PWR_STATE_SLEEP = 0x01,
+	APPLE_RTKIT_PWR_STATE_GATED = 0x02,
+	APPLE_RTKIT_PWR_STATE_QUIESCED = 0x10,
+	APPLE_RTKIT_PWR_STATE_ON = 0x20,
+};
+
+enum { APPLE_RTKIT_EP_MGMT = 0,
+	APPLE_RTKIT_EP_CRASHLOG = 1,
+	APPLE_RTKIT_EP_SYSLOG = 2,
+	APPLE_RTKIT_EP_DEBUG = 3,
+	APPLE_RTKIT_EP_IOREPORT = 4,
+	APPLE_RTKIT_EP_OSLOG = 8,
+};
+
+#define APPLE_RTKIT_MGMT_TYPE GENMASK(59, 52)
+
+enum { APPLE_RTKIT_MGMT_HELLO = 1,
+	APPLE_RTKIT_MGMT_HELLO_REPLY = 2,
+	APPLE_RTKIT_MGMT_STARTEP = 5,
+	APPLE_RTKIT_MGMT_SET_IOP_PWR_STATE = 6,
+	APPLE_RTKIT_MGMT_SET_IOP_PWR_STATE_ACK = 7,
+	APPLE_RTKIT_MGMT_EPMAP = 8,
+	APPLE_RTKIT_MGMT_EPMAP_REPLY = 8,
+	APPLE_RTKIT_MGMT_SET_AP_PWR_STATE = 0xb,
+	APPLE_RTKIT_MGMT_SET_AP_PWR_STATE_ACK = 0xb,
+};
+
+#define APPLE_RTKIT_MGMT_HELLO_MINVER GENMASK(15, 0)
+#define APPLE_RTKIT_MGMT_HELLO_MAXVER GENMASK(31, 16)
+
+#define APPLE_RTKIT_MGMT_EPMAP_LAST   BIT(51)
+#define APPLE_RTKIT_MGMT_EPMAP_BASE   GENMASK(34, 32)
+#define APPLE_RTKIT_MGMT_EPMAP_BITMAP GENMASK(31, 0)
+
+#define APPLE_RTKIT_MGMT_EPMAP_REPLY_MORE BIT(0)
+
+#define APPLE_RTKIT_MGMT_STARTEP_EP   GENMASK(39, 32)
+#define APPLE_RTKIT_MGMT_STARTEP_FLAG BIT(1)
+
+#define APPLE_RTKIT_MGMT_PWR_STATE GENMASK(15, 0)
+
+#define APPLE_RTKIT_CRASHLOG_CRASH 1
+
+#define APPLE_RTKIT_BUFFER_REQUEST	1
+#define APPLE_RTKIT_BUFFER_REQUEST_SIZE GENMASK(51, 44)
+#define APPLE_RTKIT_BUFFER_REQUEST_IOVA GENMASK(41, 0)
+
+#define APPLE_RTKIT_SYSLOG_TYPE GENMASK(59, 52)
+
+#define APPLE_RTKIT_SYSLOG_LOG 5
+
+#define APPLE_RTKIT_SYSLOG_INIT	     8
+#define APPLE_RTKIT_SYSLOG_N_ENTRIES GENMASK(7, 0)
+#define APPLE_RTKIT_SYSLOG_MSG_SIZE  GENMASK(31, 24)
+
+#define APPLE_RTKIT_OSLOG_TYPE GENMASK(63, 56)
+#define APPLE_RTKIT_OSLOG_INIT	1
+#define APPLE_RTKIT_OSLOG_ACK	3
+
+#define APPLE_RTKIT_MIN_SUPPORTED_VERSION 11
+#define APPLE_RTKIT_MAX_SUPPORTED_VERSION 12
+
+bool apple_rtkit_is_running(struct apple_rtkit *rtk)
+{
+	if (rtk->crashed)
+		return false;
+	if ((rtk->iop_power_state & 0xff) != APPLE_RTKIT_PWR_STATE_ON)
+		return false;
+	if ((rtk->ap_power_state & 0xff) != APPLE_RTKIT_PWR_STATE_ON)
+		return false;
+	return true;
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_is_running);
+
+bool apple_rtkit_is_crashed(struct apple_rtkit *rtk)
+{
+	return rtk->crashed;
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_is_crashed);
+
+static void apple_rtkit_management_send(struct apple_rtkit *rtk, u8 type,
+					u64 msg)
+{
+	msg &= ~APPLE_RTKIT_MGMT_TYPE;
+	msg |= FIELD_PREP(APPLE_RTKIT_MGMT_TYPE, type);
+	apple_rtkit_send_message(rtk, APPLE_RTKIT_EP_MGMT, msg);
+}
+
+static void apple_rtkit_management_rx_hello(struct apple_rtkit *rtk, u64 msg)
+{
+	u64 reply;
+
+	int min_ver = FIELD_GET(APPLE_RTKIT_MGMT_HELLO_MINVER, msg);
+	int max_ver = FIELD_GET(APPLE_RTKIT_MGMT_HELLO_MAXVER, msg);
+	int want_ver = min(APPLE_RTKIT_MAX_SUPPORTED_VERSION, max_ver);
+
+	rtk_dbg("Min ver %d, max ver %d\n", min_ver, max_ver);
+
+	if (min_ver > APPLE_RTKIT_MAX_SUPPORTED_VERSION) {
+		rtk_err("Firmware min version %d is too new\n", min_ver);
+		goto abort_boot;
+	}
+
+	if (max_ver < APPLE_RTKIT_MIN_SUPPORTED_VERSION) {
+		rtk_err("Firmware max version %d is too old\n", max_ver);
+		goto abort_boot;
+	}
+
+	rtk_info("Initializing (protocol version %d)\n", want_ver);
+	rtk->version = want_ver;
+
+	reply = FIELD_PREP(APPLE_RTKIT_MGMT_HELLO_MINVER, want_ver);
+	reply |= FIELD_PREP(APPLE_RTKIT_MGMT_HELLO_MAXVER, want_ver);
+	apple_rtkit_management_send(rtk, APPLE_RTKIT_MGMT_HELLO_REPLY, reply);
+
+	return;
+
+abort_boot:
+	rtk->boot_result = -EINVAL;
+	complete_all(&rtk->epmap_completion);
+}
+
+static void apple_rtkit_management_rx_epmap(struct apple_rtkit *rtk, u64 msg)
+{
+	int i, ep;
+	u64 reply;
+	unsigned long bitmap = FIELD_GET(APPLE_RTKIT_MGMT_EPMAP_BITMAP, msg);
+	u32 base = FIELD_GET(APPLE_RTKIT_MGMT_EPMAP_BASE, msg);
+
+	rtk_dbg("received endpoint bitmap 0x%lx with base 0x%x\n", bitmap,
+		base);
+
+	for_each_set_bit(i, &bitmap, 32) {
+		ep = 32 * base + i;
+		rtk_dbg("Discovered endpoint 0x%02x\n", ep);
+		set_bit(ep, rtk->endpoints);
+	}
+
+	reply = FIELD_PREP(APPLE_RTKIT_MGMT_EPMAP_BASE, base);
+	if (msg & APPLE_RTKIT_MGMT_EPMAP_LAST)
+		reply |= APPLE_RTKIT_MGMT_EPMAP_LAST;
+	else
+		reply |= APPLE_RTKIT_MGMT_EPMAP_REPLY_MORE;
+
+	apple_rtkit_management_send(rtk, APPLE_RTKIT_MGMT_EPMAP_REPLY, reply);
+
+	if (!(msg & APPLE_RTKIT_MGMT_EPMAP_LAST))
+		return;
+
+	for_each_set_bit(ep, rtk->endpoints, APPLE_RTKIT_APP_ENDPOINT_START) {
+		switch (ep) {
+		/* the management endpoint is started by default */
+		case APPLE_RTKIT_EP_MGMT:
+			break;
+
+		/* without starting these RTKit refuses to boot */
+		case APPLE_RTKIT_EP_SYSLOG:
+		case APPLE_RTKIT_EP_CRASHLOG:
+		case APPLE_RTKIT_EP_DEBUG:
+		case APPLE_RTKIT_EP_IOREPORT:
+		case APPLE_RTKIT_EP_OSLOG:
+			rtk_dbg("Starting system endpoint 0x%02x\n", ep);
+			apple_rtkit_start_ep(rtk, ep);
+			break;
+
+		default:
+			rtk_warn("Unknown system endpoint: 0x%02x\n", ep);
+		}
+	}
+
+	complete_all(&rtk->epmap_completion);
+}
+
+static void apple_rtkit_management_rx_iop_pwr_ack(struct apple_rtkit *rtk,
+						  u64 msg)
+{
+	unsigned int new_state = FIELD_GET(APPLE_RTKIT_MGMT_PWR_STATE, msg);
+
+	rtk_dbg("IOP power state transition: 0x%x -> 0x%x\n",
+		rtk->iop_power_state, new_state);
+	rtk->iop_power_state = new_state;
+
+	complete_all(&rtk->iop_pwr_ack_completion);
+}
+
+static void apple_rtkit_management_rx_ap_pwr_ack(struct apple_rtkit *rtk,
+						 u64 msg)
+{
+	unsigned int new_state = FIELD_GET(APPLE_RTKIT_MGMT_PWR_STATE, msg);
+
+	rtk_dbg("AP power state transition: 0x%x -> 0x%x\n",
+		rtk->ap_power_state, new_state);
+	rtk->ap_power_state = new_state;
+
+	complete_all(&rtk->ap_pwr_ack_completion);
+}
+
+static void apple_rtkit_management_rx(struct apple_rtkit *rtk, u64 msg)
+{
+	u8 type = FIELD_GET(APPLE_RTKIT_MGMT_TYPE, msg);
+
+	switch (type) {
+	case APPLE_RTKIT_MGMT_HELLO:
+		apple_rtkit_management_rx_hello(rtk, msg);
+		break;
+	case APPLE_RTKIT_MGMT_EPMAP:
+		apple_rtkit_management_rx_epmap(rtk, msg);
+		break;
+	case APPLE_RTKIT_MGMT_SET_IOP_PWR_STATE_ACK:
+		apple_rtkit_management_rx_iop_pwr_ack(rtk, msg);
+		break;
+	case APPLE_RTKIT_MGMT_SET_AP_PWR_STATE_ACK:
+		apple_rtkit_management_rx_ap_pwr_ack(rtk, msg);
+		break;
+	default:
+		rtk_warn("unknown management message: 0x%llx (type: 0x%02x)\n",
+			 msg, type);
+	}
+}
+
+static int apple_rtkit_common_rx_get_buffer(struct apple_rtkit *rtk,
+					    struct apple_rtkit_shmem *buffer,
+					    u8 ep, u64 msg)
+{
+	size_t n_4kpages = FIELD_GET(APPLE_RTKIT_BUFFER_REQUEST_SIZE, msg);
+	size_t size = n_4kpages << 12;
+	dma_addr_t iova = FIELD_GET(APPLE_RTKIT_BUFFER_REQUEST_IOVA, msg);
+	u64 reply;
+	int err;
+
+	rtk_dbg("buffer request for 0x%zx bytes at %pad\n", size, &iova);
+
+	if (iova && (!rtk->ops->shmem_setup || !rtk->ops->shmem_destroy))
+		return -EINVAL;
+
+	if (rtk->ops->shmem_setup) {
+		err = rtk->ops->shmem_setup(rtk->cookie, buffer, iova, size);
+		if (err < 0)
+			return err;
+	} else {
+		buffer->buffer =
+			dma_alloc_coherent(rtk->dev, size, &iova, GFP_KERNEL);
+		if (!buffer->buffer)
+			return -ENOMEM;
+
+		buffer->size = size;
+		buffer->iova = iova;
+	}
+
+	if (!buffer->is_mapped) {
+		reply = FIELD_PREP(APPLE_RTKIT_SYSLOG_TYPE,
+				   APPLE_RTKIT_BUFFER_REQUEST);
+		reply |= FIELD_PREP(APPLE_RTKIT_BUFFER_REQUEST_SIZE, n_4kpages);
+		reply |= FIELD_PREP(APPLE_RTKIT_BUFFER_REQUEST_IOVA,
+				    buffer->iova);
+		apple_rtkit_send_message(rtk, ep, reply);
+	}
+
+	return 0;
+}
+
+static void apple_rtkit_free_buffer(struct apple_rtkit *rtk,
+				    struct apple_rtkit_shmem *bfr)
+{
+	if (bfr->size == 0)
+		return;
+
+	if (rtk->ops->shmem_destroy)
+		rtk->ops->shmem_destroy(rtk->cookie, bfr);
+	else if (bfr->buffer)
+		dma_free_coherent(rtk->dev, bfr->size, bfr->buffer, bfr->iova);
+
+	bfr->buffer = NULL;
+	bfr->iomem = NULL;
+	bfr->iova = 0;
+	bfr->size = 0;
+	bfr->is_mapped = false;
+}
+
+static void apple_rtkit_memcpy(struct apple_rtkit *rtk, void *dst,
+			       struct apple_rtkit_shmem *bfr, size_t offset,
+			       size_t len)
+{
+	if (bfr->iomem)
+		memcpy_fromio(dst, bfr->iomem + offset, len);
+	else
+		memcpy(dst, bfr->buffer + offset, len);
+}
+
+static void apple_rtkit_crashlog_rx(struct apple_rtkit *rtk, u64 msg)
+{
+	u8 type = FIELD_GET(APPLE_RTKIT_SYSLOG_TYPE, msg);
+	u8 *bfr;
+
+	if (type != APPLE_RTKIT_CRASHLOG_CRASH) {
+		rtk_warn("Unknown crashlog message: %llx\n", msg);
+		return;
+	}
+
+	if (!rtk->crashlog_buffer.size) {
+		apple_rtkit_common_rx_get_buffer(rtk, &rtk->crashlog_buffer,
+						 APPLE_RTKIT_EP_CRASHLOG, msg);
+		return;
+	}
+
+	rtk_err("co-processor has crashed.\n");
+
+	/*
+	 * create a shadow copy here to make sure the co-processor isn't able
+	 * to change the log while we're dumping it. this also ensures
+	 * the buffer is in normal memory and not iomem for e.g. the SMC
+	 */
+	bfr = kzalloc(rtk->crashlog_buffer.size, GFP_KERNEL);
+	if (bfr) {
+		apple_rtkit_memcpy(rtk, bfr, &rtk->crashlog_buffer, 0,
+				   rtk->crashlog_buffer.size);
+		apple_rtkit_crashlog_dump(rtk, bfr, rtk->crashlog_buffer.size);
+		kfree(bfr);
+	} else {
+		rtk_err("Couldn't allocate crashlog shadow buffer.");
+	}
+
+	rtk->crashed = true;
+	if (rtk->ops->crashed)
+		rtk->ops->crashed(rtk->cookie);
+}
+
+static void apple_rtkit_ioreport_rx(struct apple_rtkit *rtk, u64 msg)
+{
+	u8 type = FIELD_GET(APPLE_RTKIT_SYSLOG_TYPE, msg);
+
+	switch (type) {
+	case APPLE_RTKIT_BUFFER_REQUEST:
+		apple_rtkit_common_rx_get_buffer(rtk, &rtk->ioreport_buffer,
+						 APPLE_RTKIT_EP_IOREPORT, msg);
+		break;
+	/* unknown, must be ACKed or the co-processor will hang */
+	case 0x8:
+	case 0xc:
+		apple_rtkit_send_message(rtk, APPLE_RTKIT_EP_IOREPORT, msg);
+		break;
+	default:
+		rtk_warn("Unknown ioreport message: %llx\n", msg);
+	}
+}
+
+static void apple_rtkit_syslog_rx_init(struct apple_rtkit *rtk, u64 msg)
+{
+	rtk->syslog_n_entries = FIELD_GET(APPLE_RTKIT_SYSLOG_N_ENTRIES, msg);
+	rtk->syslog_msg_size = FIELD_GET(APPLE_RTKIT_SYSLOG_MSG_SIZE, msg);
+
+	rtk->syslog_msg_buffer = kzalloc(rtk->syslog_msg_size, GFP_KERNEL);
+
+	rtk_dbg("syslog initialized: entries: %zd, msg_size: %zd\n",
+		rtk->syslog_n_entries, rtk->syslog_msg_size);
+}
+
+static void apple_rtkit_syslog_rx_log(struct apple_rtkit *rtk, u64 msg)
+{
+	u8 idx = msg & 0xff;
+	char log_context[24];
+	size_t entry_size = 0x20 + rtk->syslog_msg_size;
+
+	if (!rtk->syslog_buffer.size) {
+		rtk_warn(
+			"received syslog message but syslog_buffer.size is zero");
+		goto done;
+	}
+	if (!rtk->syslog_buffer.buffer && !rtk->syslog_buffer.iomem) {
+		rtk_warn("received syslog message but no syslog_buffer.buffer or syslog_buffer.iomem");
+		goto done;
+	}
+	if (idx > rtk->syslog_n_entries) {
+		rtk_warn("syslog index %d out of range", idx);
+		goto done;
+	}
+
+	apple_rtkit_memcpy(rtk, log_context, &rtk->syslog_buffer,
+			   idx * entry_size + 8, sizeof(log_context));
+	apple_rtkit_memcpy(rtk, rtk->syslog_msg_buffer, &rtk->syslog_buffer,
+			   idx * entry_size + 8 + sizeof(log_context),
+			   rtk->syslog_msg_size);
+
+	log_context[sizeof(log_context) - 1] = 0;
+	rtk->syslog_msg_buffer[rtk->syslog_msg_size - 1] = 0;
+	rtk_info("syslog message: %s: %s", log_context, rtk->syslog_msg_buffer);
+
+done:
+	apple_rtkit_send_message(rtk, APPLE_RTKIT_EP_SYSLOG, msg);
+}
+
+static void apple_rtkit_syslog_rx(struct apple_rtkit *rtk, u64 msg)
+{
+	u8 type = FIELD_GET(APPLE_RTKIT_SYSLOG_TYPE, msg);
+
+	switch (type) {
+	case APPLE_RTKIT_BUFFER_REQUEST:
+		apple_rtkit_common_rx_get_buffer(rtk, &rtk->syslog_buffer,
+						 APPLE_RTKIT_EP_SYSLOG, msg);
+		break;
+	case APPLE_RTKIT_SYSLOG_INIT:
+		apple_rtkit_syslog_rx_init(rtk, msg);
+		break;
+	case APPLE_RTKIT_SYSLOG_LOG:
+		apple_rtkit_syslog_rx_log(rtk, msg);
+		break;
+	default:
+		rtk_warn("Unknown syslog message: %llx\n", msg);
+	}
+}
+
+static void apple_rtkit_oslog_rx_init(struct apple_rtkit *rtk, u64 msg)
+{
+	u64 ack;
+
+	rtk_dbg("oslog init: msg: 0x%llx\n", msg);
+	ack = FIELD_PREP(APPLE_RTKIT_OSLOG_TYPE, APPLE_RTKIT_OSLOG_ACK);
+	apple_rtkit_send_message(rtk, APPLE_RTKIT_EP_OSLOG, ack);
+}
+
+static void apple_rtkit_oslog_rx(struct apple_rtkit *rtk, u64 msg)
+{
+	u8 type = FIELD_GET(APPLE_RTKIT_OSLOG_TYPE, msg);
+
+	switch (type) {
+	case APPLE_RTKIT_OSLOG_INIT:
+		apple_rtkit_oslog_rx_init(rtk, msg);
+		break;
+	default:
+		rtk_warn("Unknown oslog message: %llx\n", msg);
+	}
+}
+
+static void apple_rtkit_rx(struct apple_rtkit *rtk, struct apple_mbox_msg *msg)
+{
+	u8 ep = msg->msg1;
+
+	if (!test_bit(ep, rtk->endpoints))
+		rtk_warn("Message to undiscovered endpoint 0x%02x", ep);
+
+	switch (ep) {
+	case APPLE_RTKIT_EP_MGMT:
+		apple_rtkit_management_rx(rtk, msg->msg0);
+		break;
+	case APPLE_RTKIT_EP_CRASHLOG:
+		apple_rtkit_crashlog_rx(rtk, msg->msg0);
+		break;
+	case APPLE_RTKIT_EP_SYSLOG:
+		apple_rtkit_syslog_rx(rtk, msg->msg0);
+		break;
+	case APPLE_RTKIT_EP_IOREPORT:
+		apple_rtkit_ioreport_rx(rtk, msg->msg0);
+		break;
+	case APPLE_RTKIT_EP_OSLOG:
+		apple_rtkit_oslog_rx(rtk, msg->msg0);
+		break;
+	case APPLE_RTKIT_APP_ENDPOINT_START ... 0xff:
+		rtk->ops->recv_message(rtk->cookie, ep, msg->msg0);
+		break;
+	default:
+		rtk_warn("message to unknown endpoint %02x: %llx\n", ep,
+			 msg->msg0);
+	}
+}
+
+static void apple_rtkit_do_reinit(struct apple_rtkit *rtk)
+{
+	apple_rtkit_free_buffer(rtk, &rtk->ioreport_buffer);
+	apple_rtkit_free_buffer(rtk, &rtk->crashlog_buffer);
+	apple_rtkit_free_buffer(rtk, &rtk->syslog_buffer);
+
+	kfree(rtk->syslog_msg_buffer);
+
+	rtk->syslog_msg_buffer = NULL;
+	rtk->syslog_n_entries = 0;
+	rtk->syslog_msg_size = 0;
+
+	bitmap_zero(rtk->endpoints, APPLE_RTKIT_MAX_ENDPOINTS);
+	set_bit(APPLE_RTKIT_EP_MGMT, rtk->endpoints);
+
+	reinit_completion(&rtk->epmap_completion);
+	reinit_completion(&rtk->iop_pwr_ack_completion);
+	reinit_completion(&rtk->ap_pwr_ack_completion);
+
+	rtk->crashed = false;
+	rtk->iop_power_state = APPLE_RTKIT_PWR_STATE_OFF;
+	rtk->ap_power_state = APPLE_RTKIT_PWR_STATE_OFF;
+
+	complete_all(&rtk->reinit_completion);
+}
+
+static int apple_rtkit_worker(void *data)
+{
+	struct apple_rtkit *rtk = data;
+	struct apple_rtkit_work work;
+
+	while (!kthread_should_stop()) {
+		wait_event_interruptible(rtk->wq,
+					 kfifo_len(&rtk->work_fifo) > 0 ||
+						 kthread_should_stop());
+
+		if (kthread_should_stop())
+			break;
+
+		while (kfifo_out_spinlocked(&rtk->work_fifo, &work, 1,
+					    &rtk->work_lock) == 1) {
+			switch (work.type) {
+			case APPLE_RTKIT_WORK_MSG:
+				apple_rtkit_rx(rtk, &work.msg);
+				break;
+			case APPLE_RTKIT_WORK_REINIT:
+				apple_rtkit_do_reinit(rtk);
+				break;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static void apple_rtkit_rx_callback(struct mbox_client *cl, void *mssg)
+{
+	struct apple_rtkit *rtk = container_of(cl, struct apple_rtkit, mbox_cl);
+	struct apple_mbox_msg *msg = mssg;
+	struct apple_rtkit_work work;
+
+	dma_rmb();
+
+	memcpy(&work.msg, msg, sizeof(*msg));
+	work.type = APPLE_RTKIT_WORK_MSG;
+
+	kfifo_in_spinlocked(&rtk->work_fifo, &work, 1, &rtk->work_lock);
+	wake_up(&rtk->wq);
+}
+
+int apple_rtkit_send_message(struct apple_rtkit *rtk, u8 ep, u64 message)
+{
+	struct apple_mbox_msg msg;
+
+	if (rtk->crashed)
+		return -EINVAL;
+	if (ep >= APPLE_RTKIT_APP_ENDPOINT_START &&
+	    !apple_rtkit_is_running(rtk))
+		return -EINVAL;
+
+	msg.msg0 = (u64)message;
+	msg.msg1 = ep;
+	dma_wmb();
+
+	return mbox_send_message(rtk->mbox_chan, &msg);
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_send_message);
+
+int apple_rtkit_start_ep(struct apple_rtkit *rtk, u8 endpoint)
+{
+	u64 msg;
+
+	if (!test_bit(endpoint, rtk->endpoints))
+		return -EINVAL;
+	if (endpoint >= APPLE_RTKIT_APP_ENDPOINT_START &&
+	    !apple_rtkit_is_running(rtk))
+		return -EINVAL;
+
+	msg = FIELD_PREP(APPLE_RTKIT_MGMT_STARTEP_EP, endpoint);
+	msg |= APPLE_RTKIT_MGMT_STARTEP_FLAG;
+	apple_rtkit_management_send(rtk, APPLE_RTKIT_MGMT_STARTEP, msg);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_start_ep);
+
+static int apple_rtkit_start_worker(struct apple_rtkit *rtk)
+{
+	rtk->task = kthread_run(apple_rtkit_worker, rtk, "%s-rtkit-worker",
+				dev_name(rtk->dev));
+	if (IS_ERR(rtk->task))
+		return PTR_ERR(rtk->task);
+	return 0;
+}
+
+struct apple_rtkit *apple_rtkit_init(struct device *dev, void *cookie,
+				     const char *mbox_name, int mbox_idx,
+				     const struct apple_rtkit_ops *ops)
+{
+	struct apple_rtkit *rtk;
+	int ret;
+
+	if (!ops)
+		return ERR_PTR(-EINVAL);
+
+	rtk = kzalloc(sizeof(*rtk), GFP_KERNEL);
+	if (!rtk)
+		return ERR_PTR(-ENOMEM);
+
+	rtk->dev = dev;
+	rtk->cookie = cookie;
+	rtk->ops = ops;
+
+	INIT_KFIFO(rtk->work_fifo);
+	spin_lock_init(&rtk->work_lock);
+	init_waitqueue_head(&rtk->wq);
+	init_completion(&rtk->epmap_completion);
+	init_completion(&rtk->reinit_completion);
+	init_completion(&rtk->iop_pwr_ack_completion);
+	init_completion(&rtk->ap_pwr_ack_completion);
+
+	bitmap_zero(rtk->endpoints, APPLE_RTKIT_MAX_ENDPOINTS);
+	set_bit(APPLE_RTKIT_EP_MGMT, rtk->endpoints);
+
+	ret = apple_rtkit_start_worker(rtk);
+	if (ret)
+		return ERR_PTR(ret);
+
+	rtk->mbox_cl.dev = dev;
+	rtk->mbox_cl.tx_block = true;
+	rtk->mbox_cl.knows_txdone = false;
+	rtk->mbox_cl.rx_callback = &apple_rtkit_rx_callback;
+
+	if (mbox_name)
+		rtk->mbox_chan =
+			mbox_request_channel_byname(&rtk->mbox_cl, mbox_name);
+	else
+		rtk->mbox_chan = mbox_request_channel(&rtk->mbox_cl, mbox_idx);
+
+	if (IS_ERR(rtk->mbox_chan))
+		return (struct apple_rtkit *)rtk->mbox_chan;
+
+	return rtk;
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_init);
+
+static int apple_rtkit_wait_for_completion(struct completion *c)
+{
+	long t;
+
+	t = wait_for_completion_interruptible_timeout(c,
+						      msecs_to_jiffies(1000));
+	if (t == -ERESTARTSYS)
+		return t;
+	else if (t == 0)
+		return -ETIME;
+	else
+		return 0;
+}
+
+int apple_rtkit_reinit(struct apple_rtkit *rtk)
+{
+	struct apple_rtkit_work work;
+
+	reinit_completion(&rtk->reinit_completion);
+
+	work.type = APPLE_RTKIT_WORK_REINIT;
+	kfifo_in_spinlocked(&rtk->work_fifo, &work, 1, &rtk->work_lock);
+	wake_up(&rtk->wq);
+
+	return apple_rtkit_wait_for_completion(&rtk->reinit_completion);
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_reinit);
+
+static int apple_rtkit_set_ap_power_state(struct apple_rtkit *rtk,
+					  unsigned int state)
+{
+	u64 msg;
+	int ret;
+
+	reinit_completion(&rtk->ap_pwr_ack_completion);
+
+	msg = FIELD_PREP(APPLE_RTKIT_MGMT_PWR_STATE, state);
+	apple_rtkit_management_send(rtk, APPLE_RTKIT_MGMT_SET_AP_PWR_STATE,
+				    msg);
+
+	ret = apple_rtkit_wait_for_completion(&rtk->ap_pwr_ack_completion);
+	if (ret)
+		return ret;
+
+	if (rtk->ap_power_state != state)
+		return -EINVAL;
+	return 0;
+}
+
+static int apple_rtkit_set_iop_power_state(struct apple_rtkit *rtk,
+					   unsigned int state)
+{
+	u64 msg;
+	int ret;
+
+	reinit_completion(&rtk->iop_pwr_ack_completion);
+
+	msg = FIELD_PREP(APPLE_RTKIT_MGMT_PWR_STATE, state);
+	apple_rtkit_management_send(rtk, APPLE_RTKIT_MGMT_SET_IOP_PWR_STATE,
+				    msg);
+
+	ret = apple_rtkit_wait_for_completion(&rtk->iop_pwr_ack_completion);
+	if (ret)
+		return ret;
+
+	if (rtk->iop_power_state != state)
+		return -EINVAL;
+	return 0;
+}
+
+int apple_rtkit_boot(struct apple_rtkit *rtk)
+{
+	int ret;
+
+	if (apple_rtkit_is_running(rtk))
+		return 0;
+	if (rtk->crashed)
+		return -EINVAL;
+
+	rtk_dbg("waiting for boot to finish\n");
+	ret = apple_rtkit_wait_for_completion(&rtk->epmap_completion);
+	if (ret)
+		return ret;
+	if (rtk->boot_result)
+		return rtk->boot_result;
+
+	rtk_dbg("waiting for IOP power state ACK\n");
+	ret = apple_rtkit_wait_for_completion(&rtk->iop_pwr_ack_completion);
+	if (ret)
+		return ret;
+
+	return apple_rtkit_set_ap_power_state(rtk, APPLE_RTKIT_PWR_STATE_ON);
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_boot);
+
+int apple_rtkit_shutdown(struct apple_rtkit *rtk)
+{
+	int ret;
+
+	/* if OFF is used here the co-processor will not wake up again */
+	ret = apple_rtkit_set_ap_power_state(rtk,
+					     APPLE_RTKIT_PWR_STATE_QUIESCED);
+	if (ret)
+		return ret;
+
+	ret = apple_rtkit_set_iop_power_state(rtk, APPLE_RTKIT_PWR_STATE_SLEEP);
+	if (ret)
+		return ret;
+
+	return apple_rtkit_reinit(rtk);
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_shutdown);
+
+int apple_rtkit_hibernate(struct apple_rtkit *rtk)
+{
+	int ret;
+
+	ret = apple_rtkit_set_ap_power_state(rtk,
+					     APPLE_RTKIT_PWR_STATE_QUIESCED);
+	if (ret)
+		return ret;
+
+	ret = apple_rtkit_set_iop_power_state(rtk,
+					      APPLE_RTKIT_PWR_STATE_QUIESCED);
+	if (ret)
+		return ret;
+
+	ret = apple_rtkit_reinit(rtk);
+	if (ret)
+		return ret;
+
+	// TODO: apple_rtkit_reinit resets these so we have to restore them here :/
+	rtk->iop_power_state = APPLE_RTKIT_PWR_STATE_QUIESCED;
+	rtk->ap_power_state = APPLE_RTKIT_PWR_STATE_QUIESCED;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_hibernate);
+
+int apple_rtkit_wake(struct apple_rtkit *rtk)
+{
+	u64 msg;
+
+	if (apple_rtkit_is_running(rtk))
+		return -EINVAL;
+
+	reinit_completion(&rtk->iop_pwr_ack_completion);
+
+	/*
+	 * Use open-coded apple_rtkit_set_iop_power_state since apple_rtkit_boot
+	 * will wait for the completion anyway.
+	 */
+	msg = FIELD_PREP(APPLE_RTKIT_MGMT_PWR_STATE, APPLE_RTKIT_PWR_STATE_ON);
+	apple_rtkit_management_send(rtk, APPLE_RTKIT_MGMT_SET_IOP_PWR_STATE,
+				    msg);
+
+	return apple_rtkit_boot(rtk);
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_wake);
+
+void apple_rtkit_free(struct apple_rtkit *rtk)
+{
+	kthread_stop(rtk->task);
+	mbox_free_channel(rtk->mbox_chan);
+
+	apple_rtkit_free_buffer(rtk, &rtk->ioreport_buffer);
+	apple_rtkit_free_buffer(rtk, &rtk->crashlog_buffer);
+	apple_rtkit_free_buffer(rtk, &rtk->syslog_buffer);
+
+	kfree(rtk->syslog_msg_buffer);
+	kfree(rtk);
+}
+EXPORT_SYMBOL_GPL(apple_rtkit_free);
+
+struct apple_rtkit *devm_apple_rtkit_init(struct device *dev, void *cookie,
+					  const char *mbox_name, int mbox_idx,
+					  const struct apple_rtkit_ops *ops)
+{
+	struct apple_rtkit *rtk;
+	int ret;
+
+	rtk = apple_rtkit_init(dev, cookie, mbox_name, mbox_idx, ops);
+	if (IS_ERR(rtk))
+		return rtk;
+
+	ret = devm_add_action_or_reset(dev, (void (*)(void *))apple_rtkit_free,
+				       rtk);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return rtk;
+}
+EXPORT_SYMBOL_GPL(devm_apple_rtkit_init);
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
+MODULE_DESCRIPTION("Apple RTKit driver");
diff --git a/include/linux/soc/apple/rtkit.h b/include/linux/soc/apple/rtkit.h
new file mode 100644
index 000000000000..a1beb514fff6
--- /dev/null
+++ b/include/linux/soc/apple/rtkit.h
@@ -0,0 +1,203 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+/*
+ * Apple RTKit IPC Library
+ * Copyright (C) The Asahi Linux Contributors
+ *
+ * Apple's SoCs come with various co-processors running their RTKit operating
+ * system. This protocol library is used by client drivers to use the
+ * features provided by them.
+ */
+#ifndef _LINUX_APPLE_RTKIT_H_
+#define _LINUX_APPLE_RTKIT_H_
+
+#include <linux/device.h>
+#include <linux/ioport.h>
+#include <linux/types.h>
+#include <linux/mailbox_client.h>
+
+/*
+ * Struct to represent implementation-specific RTKit operations.
+ *
+ * @buffer:    Shared memory buffer allocated inside normal RAM.
+ * @iomem:     Shared memory buffer controlled by the co-processors.
+ * @size:      Size of the shared memory buffer.
+ * @iova:      Device VA of shared memory buffer.
+ * @is_mapped: Shared memory buffer is managed by the co-processor.
+ */
+
+struct apple_rtkit_shmem {
+	void *buffer;
+	void __iomem *iomem;
+	size_t size;
+	dma_addr_t iova;
+	bool is_mapped;
+};
+
+/*
+ * Struct to represent implementation-specific RTKit operations.
+ *
+ * @crashed:       Called when the co-processor has crashed.
+ * @recv_message:  Function called when a message from RTKit is received
+ *                 on a non-system endpoint. Called from a worker thread.
+ * @shmem_setup:   Setup shared memory buffer. If bfr.is_iomem is true the
+ *                 buffer is managed by the co-processor and needs to be mapped.
+ *                 Otherwise the buffer is managed by Linux and needs to be
+ *                 allocated. If not specified dma_alloc_coherent is used.
+ * @shmem_destroy: Undo the shared memory buffer setup in shmem_setup. If not
+ *                 specified dma_free_coherent is used.
+ */
+struct apple_rtkit_ops {
+	void (*crashed)(void *cookie);
+	void (*recv_message)(void *cookie, u8 endpoint, u64 message);
+	int (*shmem_setup)(void *cookie, struct apple_rtkit_shmem *bfr,
+			   dma_addr_t addr, size_t len);
+	void (*shmem_destroy)(void *cookie, struct apple_rtkit_shmem *bfr);
+};
+
+struct apple_rtkit;
+
+#if IS_ENABLED(CONFIG_APPLE_RTKIT)
+
+/*
+ * Initializes the internal state required to handle RTKit. This
+ * should usually be called within _probe.
+ *
+ * @dev: Pointer to the device node this coprocessor is assocated with
+ * @cookie: opaque cookie passed to all functions defined in rtkit_ops
+ * @mbox_name: mailbox name used to communicate with the co-processor
+ * @mbox_idx: mailbox index to be used if mbox_name is NULL
+ * @ops: pointer to rtkit_ops to be used for this co-processor
+ */
+struct apple_rtkit *apple_rtkit_init(struct device *dev, void *cookie,
+				     const char *mbox_name, int mbox_idx,
+				     const struct apple_rtkit_ops *ops);
+
+/*
+ * Dev-res managed version of apple_rtkit_init.
+ */
+struct apple_rtkit *devm_apple_rtkit_init(struct device *dev, void *cookie,
+					  const char *mbox_name, int mbox_idx,
+					  const struct apple_rtkit_ops *ops);
+
+/*
+ * Free internal structures.
+ */
+void apple_rtkit_free(struct apple_rtkit *rtk);
+
+/*
+ * Reinitialize internal structures. Must only be called with the co-processor
+ * is held in reset.
+ */
+int apple_rtkit_reinit(struct apple_rtkit *rtk);
+
+/*
+ * Handle RTKit's boot process. Should be called after the CPU of the
+ * co-processor has been started.
+ */
+int apple_rtkit_boot(struct apple_rtkit *rtk);
+
+/*
+ * Hibernate the co-processor.
+ */
+int apple_rtkit_hibernate(struct apple_rtkit *rtk);
+
+/*
+ * Wake the co-processor up from hibernation mode.
+ */
+int apple_rtkit_wake(struct apple_rtkit *rtk);
+
+/*
+ * Shutdown the co-processor
+ */
+int apple_rtkit_shutdown(struct apple_rtkit *rtk);
+
+/*
+ * Checks if RTKit is running and ready to handle messages.
+ */
+bool apple_rtkit_is_running(struct apple_rtkit *rtk);
+
+/*
+ * Checks if RTKit has crashed.
+ */
+bool apple_rtkit_is_crashed(struct apple_rtkit *rtk);
+
+/*
+ * Starts an endpoint. Must be called after boot but before any messages can be
+ * sent or received from that endpoint.
+ */
+int apple_rtkit_start_ep(struct apple_rtkit *rtk, u8 endpoint);
+
+/*
+ * Send a message to the given endpoint.
+ */
+int apple_rtkit_send_message(struct apple_rtkit *rtk, u8 ep, u64 message);
+
+#else
+
+static inline struct apple_rtkit *
+apple_rtkit_init(struct device *dev, void *cookie, const char *mbox_name,
+		 int mbox_idx, const struct apple_rtkit_ops *ops)
+{
+	return ERR_PTR(-ENODEV);
+}
+
+static inline struct apple_rtkit *
+devm_apple_rtkit_init(struct device *dev, void *cookie, const char *mbox_name,
+		      int mbox_idx, const struct apple_rtkit_ops *ops)
+{
+	return ERR_PTR(-ENODEV);
+}
+
+static inline void apple_rtkit_free(struct apple_rtkit *rtk)
+{
+}
+
+static inline int apple_rtkit_reinit(struct apple_rtkit *rtk)
+{
+	return -ENODEV;
+}
+
+static inline int apple_rtkit_boot(struct apple_rtkit *rtk)
+{
+	return -ENODEV;
+}
+
+static inline int apple_rtkit_hibernate(struct apple_rtkit *rtk)
+{
+	return -ENODEV;
+}
+
+static inline int apple_rtkit_wake(struct apple_rtkit *rtk)
+{
+	return -ENODEV;
+}
+
+static inline int apple_rtkit_shutdown(struct apple_rtkit *rtk)
+{
+	return -ENODEV;
+}
+
+static inline bool apple_rtkit_is_running(struct apple_rtkit *rtk)
+{
+	return false;
+}
+
+static inline bool apple_rtkit_is_crashed(struct apple_rtkit *rtk)
+{
+	return false;
+}
+
+static inline int apple_rtkit_start_ep(struct apple_rtkit *rtk, u8 endpoint)
+{
+	return -ENODEV;
+}
+
+static inline int apple_rtkit_send_message(struct apple_rtkit *rtk, u8 ep,
+					   u64 message)
+{
+	return -ENODEV;
+}
+
+#endif /* IS_ENABLED(CONFIG_APPLE_RTKIT) */
+
+#endif /* _LINUX_APPLE_RTKIT_H_ */