linux-kernel - Re: [PATCH V2] firmware: arm_scmi: Make scmi core independent of transport type

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Message-ID: <20200114111110.jhkj2y47ncp5233r@vireshk-i7>
Date:   Tue, 14 Jan 2020 16:41:10 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Jassi Brar <jassisinghbrar@...il.com>,
        cristian.marussi@....com, peng.fan@....com,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V2] firmware: arm_scmi: Make scmi core independent of
 transport type

On 14-01-20, 10:56, Arnd Bergmann wrote:
> My point was that you cannot mix __iomem accesses with pointer
> accesses. As I understood it, the current version uses a pointer to a

The current version is stupid as I misunderstood the whole __iomem
thing and just dropped it :)

> hardware mailbox with structured data, so you have to use ioremap()
> to get a token you can pass into ioread(), but (some of) the new
> transport types would just be backed by regular RAM, on which this
> is not a well-defined operation and you have to use memremap()
> and memcpy() instead.

Okay, I think I understand that a bit now. So here are the things
which I may need to do now:

- Maybe move payload to struct scmi_mailbox structure, as that is the
  transport dependent structure..

- Do ioremap, etc in mailbox.c only instead of driver.c

- Provide more ops in struct scmi_transport_ops to provide read/write
  helpers to the payload and implement the ones based on
  ioread/iowrite in mailbox.c ..

Am I thinking in the right direction now ?

-- 
viresh