Re: [PATCH V2 05/10] firmware: tegra: add BPMP support

[Stephen Warren]

On 07/06/2016 05:39 AM, Alexandre Courbot wrote:
> Sorry, I will probably need to do several passes on this one to
> understand everything, but here is what I can say after a first look:
>
> On Tue, Jul 5, 2016 at 6:04 PM, Joseph Lo <josephl@xxxxxxxxxx> wrote:
> > The Tegra BPMP (Boot and Power Management Processor) is designed for the
> > booting process handling, offloading the power management tasks and
> > some system control services from the CPU. It can be clock, DVFS,
> > thermal/EDP, power gating operation and system suspend/resume handling.
> > So the CPU and the drivers of these modules can base on the service that
> > the BPMP firmware driver provided to signal the event for the specific PM
> > action to BPMP and receive the status update from BPMP.
> >
> > Comparing to the ARM SCPI, the service provided by BPMP is message-based
> > communication but not method-based. The BPMP firmware driver provides the
> > send/receive service for the users, when the user concerns the response
> > time. If the user needs to get the event or update from the firmware, it
> > can request the MRQ service as well. The user needs to take care of the
> > message format, which we call BPMP ABI.
> >
> > The BPMP ABI defines the message format for different modules or usages.
> > For example, the clock operation needs an MRQ service code called
> > MRQ_CLK with specific message format which includes different sub
> > commands for various clock operations. This is the message format that
> > BPMP can recognize.
> >
> > So the user needs two things to initiate IPC between BPMP. Get the
> > service from the bpmp_ops structure and maintain the message format as
> > the BPMP ABI defined.

> > diff --git a/include/soc/tegra/bpmp_abi.h b/include/soc/tegra/bpmp_abi.h

> > +#ifndef _ABI_BPMP_ABI_H_
> > +#define _ABI_BPMP_ABI_H_
> > +
> > +#ifdef LK
> > +#include <stdint.h>
> > +#endif
> > +
> > +#ifndef __ABI_PACKED
> > +#define __ABI_PACKED __attribute__((packed))
> > +#endif
> > +
> > +#ifdef NO_GCC_EXTENSIONS
> > +#define EMPTY char empty;
> > +#define EMPTY_ARRAY 1
> > +#else
> > +#define EMPTY
> > +#define EMPTY_ARRAY 0
> > +#endif
> > +
> > +#ifndef __UNION_ANON
> > +#define __UNION_ANON
> > +#endif
> > +/**
> > + * @file
> > + */
> > +
> > +
> > +/**
> > + * @defgroup MRQ MRQ Messages
> > + * @brief Messages sent to/from BPMP via IPC
> > + * @{
> > + *   @defgroup MRQ_Format Message Format
> > + *   @defgroup MRQ_Codes Message Request (MRQ) Codes
> > + *   @defgroup MRQ_Payloads Message Payloads
> > + *   @defgroup Error_Codes Error Codes
> > + * @}
> > + */
>
> ...
>
> There is a lot of stuff in this file, most of which we are not using
> now - this is ok, but unless this is a file synced from an outside
> resource maybe we should trim the structures we don't need and add
> them as we make use of them? It helps dividing the work in bite-size
> chunks.
>
> Regarding the documentation format of this file, is this valid kernel
> documentation since the adoption of Sphynx? Or is it whatever the
> origin is using?

This file is an ABI document published by the BPMP FW team. I believe it 
would be best to use it unmodified.