Apparatus for managing power and running and booting an inter-processor communication link between independently operable processors

Patent metadata

Field	Value
Publication number	US-10372199-B2
Application number	US-201715721200-A
Country	US
Kind code	B2
Filing date	Sep 29, 2017
Priority date	Oct 8, 2014
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

Methods and apparatus for an inter-processor communication (IPC) link between two (or more) independently operable processors. In one aspect, the IPC protocol is based on a “shared” memory interface for run-time processing (i.e., the independently operable processors each share (either virtually or physically) a common memory interface). In another aspect, the IPC communication link is configured to support a host driven boot protocol used during a boot sequence to establish a basic communication path between the peripheral and the host processors. Various other embodiments described herein include sleep procedures (as defined separately for the host and peripheral processors), and error handling.

First claim

What is claimed is:

1. A non-transitory computer-readable storage apparatus comprising a storage medium, the storage medium comprising computer-readable instructions that are configured to, when executed by a first digital processor apparatus:
prior to transmission of a boot state image to a second digital processor apparatus, determine a current stage of execution for the second digital processor apparatus by a read operation of a shared memory interface by the first digital processor apparatus; and
cause the first digital processor apparatus to transmit the boot stage image to the second digital processor apparatus via a physical bus interface.

2. The non-transitory computer-readable storage apparatus of claim 1 , wherein the computer-readable instructions are further configured to, when executed by the first digital processor apparatus:
prior to transmission of the boot state image to the second digital processor apparatus, detect the physical bus interface and enumerate the second digital processor apparatus;
wherein the enumeration of the second digital processor apparatus comprises an initial query of one or more devices connected to the first digital processor apparatus and an assignment of an address for the second digital processor apparatus.

3. The non-transitory computer-readable storage apparatus of claim 1 , wherein the transmission of the boot stage image to the second digital processor apparatus further comprises a map of the boot state image to the shared memory interface; and
wherein the computer-readable instructions are further configured to, when executed by the first digital processor apparatus:
subsequent to the map of the boot state image to the shared memory interface, perform a write operation to a doorbell register of the shared memory interface, the write operation to the doorbell register comprising a notification of the map of the boot state image to the shared memory interface.

4. The non-transitory computer-readable storage apparatus of claim 1 , wherein the computer-readable instructions is further configured to, when executed by the first digital processor apparatus:
perform a read operation on an image response register; and
determine a completion status for a boot sequence for the second digital processor apparatus based on the performed read operation.

5. Integrated circuit apparatus comprising:
a host processor apparatus;
an auxiliary processor apparatus; and
a shared memory interface comprising at least one data storage device, the shared memory interface in data communication with each of the host processor apparatus and the auxiliary processor apparatus, the shared memory interface configured to provide a multi-channel inter-processor communication link configured to enable data transfers between the host processor apparatus and the auxiliary processor apparatus;
wherein the integrated circuit apparatus is further configured to:
prior to transmission of a boot stage image to the auxiliary processor apparatus, determine a current stage of execution for the auxiliary processor apparatus by a read operation of the shared memory interface by the host processor apparatus; and
cause the host processor apparatus to transmit the boot stage image to the auxiliary processor apparatus via a physical bus interface.

6. The integrated circuit apparatus of claim 5 , wherein the shared memory interface is configured to remain functional when one of the host processor apparatus or the auxiliary processor apparatus is asleep.

7. The integrated circuit apparatus of claim 5 , wherein the multi-channel inter-processor communication link supports a host-driven boot protocol that is utilized during a boot sequence for the integrated circuit apparatus.

8. The integrated circuit apparatus of claim 5 , wherein the transmission of the boot stage image to the auxiliary processor apparatus further comprises a map of the boot stage image to the shared memory interface by the host processor apparatus.

9. The integrated circuit apparatus of claim 8 , wherein subsequent to the map of the boot stage image to the shared memory interface, perform a write operation to a doorbell register of the shared memory interface by the host processor apparatus, the write operation to the doorbell register comprising a notification of the map of the boot image to the shared memory interface.

10. The integrated circuit apparatus of claim 9 , wherein subsequent to the write operation to the doorbell register, the host processor apparatus performs a read operation on an image response register, the read operation on the image response register comprising a determination of a completion status for a boot sequence for the auxiliary processor apparatus.

11. The integrated circuit apparatus of claim 5 , wherein the transmission of the boot stage image to the auxiliary processor apparatus comprises provision of a base address and image size for the boot stage image within a contiguous memory space by the host processor apparatus.

12. The integrated circuit apparatus of claim 11 , wherein the determination of the current stage of execution for the auxiliary processor apparatus comprises a read of a register within the shared memory interface by the host processor apparatus.

13. The integrated circuit apparatus of claim 12 , wherein the auxiliary processor apparatus is configured to report a success or failure status for execution of the boot stage image prior to the auxiliary processor apparatus switching to run time operation.

14. A peripheral processor apparatus, comprising:
an endpoint apparatus configured to be coupled to a physical bus interface;
a processing element in communication with the endpoint apparatus; and
a communication interface coupled to a shared memory space;
wherein the peripheral processor apparatus is configured to:
cause execution of an initial primary boot sequence;
update a current execution stage for the peripheral processor apparatus by writing to the shared memory space, the update of the current execution stage configured to notify a host processor apparatus of the current execution stage for the peripheral processor apparatus;
responsive to the update of the current execution stage in the shared memory space, receive a notification from the host processor apparatus; and
responsive to receipt of the notification, retrieve a secondary boot image.

15. The peripheral processor apparatus of claim 14 , wherein the receipt of the notification from the host processor apparatus comprises a read operation of a doorbell register associated with the shared memory space between the host processor apparatus and the peripheral processor apparatus.

16. The peripheral processor apparatus of claim 15 , wherein the read operation of the doorbell register comprises a read of an image address register and an image size register of the shared memory space.

17. The peripheral processor apparatus of claim 14 , wherein the peripheral processor apparatus is further configured to verify the secondary boot image using a validation procedure prior to the retrieval of the secondary boot image.

18. The peripheral processor apparatus of claim 17 , wherein subsequent to retrieval of the secondary boot image, the peripheral processor apparatus is configured to write to a notification register on the shared memory space between the host processor apparatus and the peripheral processor apparatus.

19. The peripheral processor apparatus of claim 18 , wherein subsequent to the write of the notification register, the peripheral processor ap

Assignees

• Apple Inc

Inventors

• Sanghi Karan
• Garg Saurabh
• Zhang Haining

Classifications

• G06F11/1474

  in transactions (updating of structured data in databases G06F16/23) · CPC title

• G06F9/4403

  Processor initialisation · CPC title

• G06F2201/805

  Real-time · CPC title

• G06F1/3228

  Monitoring task completion, e.g. by use of idle timers, stop commands or wait commands · CPC title

• G06F1/3293 Primary

  by switching to a less power-consuming processor, e.g. sub-CPU · CPC title