linux-kernel - Re: [PATCH] tpm: move struct tpm_class

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Message-ID: <20160904201406.GA9854@obsidianresearch.com>
Date:   Sun, 4 Sep 2016 14:14:06 -0600
From:   Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        "moderated list:TPM DEVICE DRIVER" 
        <tpmdd-devel@...ts.sourceforge.net>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tpm: move struct tpm_class_ops to drivers/char/tpm/tpm.h

On Sat, Sep 03, 2016 at 09:26:05AM +0300, Jarkko Sakkinen wrote:
> > 
> > OK, how would one get the chip instance?

Most subsystems have a get function that returns a kref'd pointer. For
TPM all we really need today is a 'get_default_tpm_for_ns' kind of
function.

> This still doesn't explain why moving the structures inside the driver
> would be wrong. Even if outside callers would use a pointer the
> structure could be opaque.

For instance, if we did a get function then the 'put' function would
be an inline around dev_put and that needs to see inside the chip.

This is a well trodden pattern in the kernel, there is no reason to do
something different for tpm.

Jason